- Email: [email protected]
Effect of adding 0.5 wt% ZnO nanoparticles, temperature and strain rate on tensile properties of Sn–5.0 wt% Sb–0.5 wt% Cu (SSC505) lead free solder alloy
Materials Science & Engineering A 657 (2016) 104–114
Contents lists available at ScienceDirect
Materials Science & Engineering A journal homepage: www.elsevier.com/locate/msea
Effect of adding 0.5 wt% ZnO nanoparticles, temperature and strain rate on tensile properties of Sn–5.0 wt% Sb–0.5 wt% Cu (SSC505) lead free solder alloy E.A. Eid a,n, A.N. Fouda b,c, El-Shazly M. Duraia b,d a
Basic Science Department, Higher Technological Institute, 44629 10th of Ramadan City, Egypt Physics Department, Faculty of Science, Suez-Canal University, 41522 Ismailia, Egypt c Recruitment Department, University of Hail, Hail 2440, Saudi Arabia d Texas State University-San Marcos, Department of Chemistry and Biochemistry, 601 University Dr., San Marcos, TX 78666, USA b
art ic l e i nf o
a b s t r a c t
Article history: Received 18 September 2015 Received in revised form 19 December 2015 Accepted 26 January 2016 Available online 27 January 2016
This study investigates the effect of adding 0.5 wt% ZnO nanoparticles into Sn–5 wt% Sb–0.5 wt% Cu (SSC505) solder alloy on the growth of intermetallic compounds (IMCs) as well as the associated changes of microstructure. It was found that, the morphologies of the IMCs transformed to refinement forms due to the adsorption effect of ZnO nanoparticles. Systematic study of tensile properties was performed for bulk solders over a wide range of strain rates at various temperatures to determine the plastic deformation mechanism. Obviously, the ultimate tensile strength (UTS) and the yield stress (sy) were improved. This can be attributed to reinforcement of ZnO nanoparticles, refined β-Sn grains and IMCs that could obstruct the dislocation slipping. The obtained results are consistent with the prediction of the classic theory of dispersion strengthening. Furthermore, the average activation energy (Q) for plain and composite solders were 57 and 59 kJ/mol, respectively, which close to that of pipe-diffusion mechanism in Sn based solder matrix. & 2016 Elsevier B.V. All rights reserved.
Keywords: Lead-free solder Sn–Sb–Cu alloy Microstructure Composite solder Mechanical properties
1. Introduction The requirements for high reliability and integrity are challenging the solder joints performance, especially under the complicated service environments of thermal and mechanical conditions [1]. Moreover, the miniaturization of solder joints requires the increase of high packaging density (I/O) of electronic components withal better performing. Based on these facts, intensive verves have been dedicated to improve the typical reliability affairs of solder joints [1–3]. However, Pb is toxic, and is banned in many industrial applications. Therefore, the Pb-containing solder alloys are exempted from the production lines of electronic packaging [1–4]. Recently, Sn-based alloys or Pb-free solder (LFS) materials are considered as a promising replacement of Pb-containing solder alloys [1]. Toward this approach, new LFS alloys is prepared to replace high Pb-containing solder alloys [Pb–(10– 5) wt% Sn] that are extensively used in electronic power semiconductor, and optical device packaging, flip-chip packaging, etc. n
Corresponding author. E-mail addresses: [email protected] (E.A. Eid), [email protected] (A.N. Fouda). http://dx.doi.org/10.1016/j.msea.2016.01.081 0921-5093/& 2016 Elsevier B.V. All rights reserved.
[5]. In last decade, Au–20 wt% Sn is considered as the best solder alloy for most applications in optoelectronic packaging, because of its high creep resistance, wettability and good reliability [6]. This solder alloy is expensive and has high melting temperature (280 °C) which could damage the properties of optical fibers and optoelectronics such as lasers, light emitting devices, photodetectors, or waveguide devices [7,8]. Recently, Sn–5Sb alloy is considered as attractive candidate of LFS alloys when compared to Au–20Sn solder alloy. Since, it has low cost and prime mechanical properties among LFS alloys. Additionally, its wettability and tensile properties have been improved by adding ternary or quaternary alloy additions [9–15]. El-Daly et al. reported that, the addition of small amount of Cu (0.7 wt%) to the matrix of Sn–5Sb can depress the melting temperature and enhances the refinement of the IMCs without reducing the ductility of alloys [16,17]. Moreover, high reliability of solder joints is geared by adding nano-size reinforcement particles in matrix solders. Lead free composite solder (LFCS) alloys have been identified as the effective materials to provide higher microstructure stability and better mechanical properties as compared to conventional solders [2–4]. As a result, a large number of studies on LFCS alloys were performed. Generally, LFCS are containing micro or nano sized
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
Table 1 Chemical composition of the solder alloys studied (wt%).
(b)
Solder alloy
ZnO
Sb
Cu
Fe
In
As
Sn
SSC505 SSCZnO
– 0.502
5.024 5.016
0.502 0.504
0.003 0.003
0.002 0.002
0.001 0.001
Bal. Bal.
105
Sn
(a)
Sn Table 2 Tensile testing condition.
Sb Sn
Solder alloy
Strain rate (s 1)
Temperature (°C)
SSC505
5.0 × 10 2 1.0 × 10 3 5.0 × 10 3 1.0 × 10 4
50 75 100 125
SSCZnO
0
Cu O
Zn
1
2
Sb
Sn
3
4
Sn
5
Cu Zn
6
7
8
Zn
9
10
Energy (keV)
(b ) SSC ZnO
•
♣
ZnO(101) ZnO(002)
INTENSITY (arb.units)
♦
Sn SbSn Cu 6 Sn 5 ZnO 2
(a )SSC505
• •
• •
•
♣
♦
30
♣♦
♣ ♦
♦
40
•
•
50
♦• • ♣
60
♦
• • ♣
♦ 70
♣
Fig. 2. (a) FE-SEM micrograph of the SSC-ZnO composite solder to shows the existence nano-sized ZnO particles in solder matrix. (b) EDS of eutectic region of composite solder.
liquidus temperature, yield strength and ultimate tensile strength of LFCS increase significantly with the addition of nano-sized particles. On the other hand, some investigator reported that TiO2, SnO2 and Al2O3 [26–30] nano-oxide particles decompose the microstructure of β-Sn matrix and cause solid-solution hardening. Withal, Shen et al. [30,31] indicated that the addition of ZrO2 nanoparticles to Sn–3.5Ag and Sn–3.5Ag 0.5Cu solder alloy tends to suppress the growth of IMCs and refines the rode-like Ag3Sn IMC in the solder matrix and improve the microhardness as well as mechanical properties. It is worthy mentioned that, the results of research survey display little studies have been reported so far on Sn–Sb–Cu that containing ZnO nano-sized particles [8]. The aim of the current study is characterizing the Sn–5wt% Sb–0.5 wt% Cu (SSC505) plain solder and Sn–5wt% Sb–0.5 wt% Cu–0.5 wt% ZnO (SSC-ZnO) composite solder alloys in terms of as-solidified microstructures with focusing on growth and morphology of IMCs. Since the solder alloys must preserve their mechanical reliability under a myriad of conditions. Therefore, this report investigates the influence of strain rate and temperature on the tensile properties of both solder alloys, to determine the plastic deformation mechanism.
80
2 θ (degree) Fig. 1. XRD profiles of (a) SSC505 solder and (b) SSC-ZnO composite solder alloys.
2. Experimental procedure 2.1. Preparation of samples
particles serve as obstacles for grain growth and retard motion of dislocations which cause strengthen of the solder joint. Guo et al. [3] classified the reinforcement particles into two categories. (i) First category involves adding intermetallic compounds (IMCs) (e.g. Cu6Sn5, Cu3Sn or Ni3Sn4) [18–21]. (ii) Second category includes ceramic or oxide nanoparticles which have low solubility and less diffusivity with solder matrix (e.g. TiB2 [22] SiC [23–25], Al2O3 [26], TiO2 [27–29], SnO2 [30] and ZrO2 [31,32]). El-Daly et al. [33] and Fawzy et al. [34,35] investigated the effect of minor addition of ZnO nanoparticles on the microstructure, thermal property and tensile properties of Sn–Ag–Cu. They reported that the
The Sn–5wt% Sb–0.5 wt% Cu plain solder alloy was prepared from bulk Sn, Sb and Cu rods with high purity. The process of melting was performed in a vacuum furnace at 650 °C for 2 h. Then, the alloy was remelted three times in order to get a homogeneous composition. The composite solder was prepared by mechanically dispersing 0.5 wt% of ZnO nanopowder into the molten SSC505 solder and remelting in vacuum furnace at 650 °C for 2 h, then casted in a steel mold. The chemical composition of the investigated solder alloys is tabulated in Table 1. More details of composite alloys preparation are described elsewhere [8,33–35].
106
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
Fig. 3. FE-SEM micrographs shows of IMC for SSC505 plain solder alloy; (a) low magnification and (b) high magnification.
Fig. 4. FE-SEM micrographs shows of IMC for SSC-ZnO composite solder alloy; (a) low magnification and (b) high magnification.
2.2. Metallographic observation
3. Results and discussion
Scanning electron microscope (SEM) was employed to examine the microstructure of the synthesized alloys. The SEM used in this study was JEOL model JSM-5410, Japan. An energy dispersive spectrometry (EDS) was used to determine the chemical composition of the IMC phases. In addition, phase identification was examined using X-ray diffractometer (XRD) at 40 kV and 20 mA using CuKα radiation (λ ¼0.15406 nm) with diffraction angle (2θ) from 20° to 90° and constant scanning speed of 1° min 1.
3.1. X-ray diffraction (XRD) of SSC505 and SSC-ZnO composite solders
2.3. Tensile testing Tensile tests were conducted using ASTM E8/E8M-13a standard test methods for tensile tension test of metallic materials. A systematic work on tensile test was performed for the two investigated solder alloys at four testing temperatures from 50 °C up to 125 °C under different strain rates (shown in Table 2). Each datum represents an average of four measurements. The sample temperature was monitored using a thermocouple contacting the sample surface.
Fig. 1a and b depicts the XRD profile of the plain and composite solders. The obtained phases are identified by comparing the Bragg peaks with the ASTM standards. Intense peaks of β-Sn rich phase besides small peaks of SbSn and Cu6Sn5 phases have been observed. It is well known that, the dissolved Sb and Cu are precipitated by forming SbSn and Cu6Sn5 IMCs in the Sn matrix during solidification [8,14,16]. Although, the concentration of ZnO nanoparticles is relatively small, the main peaks of ZnO were detected in Fig.1b. Furthermore, the existence of ZnO nanoparticles within solidified solder was confirmed using SEM and EDS analysis as exhibited in Fig. 2. 3.2. Microstructure characterization In order to study the influence of ZnO nanoparticles on the
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
of IMCs of composite solder. Therefore, the smaller β-Sn grains and finer IMCs can increase the massive defects at the grain boundary. Additionally, ZnO at the interface boundaries could be diffused due to the limited solid solubility of ZnO in solder matrix [33–35]. Therefore, it is predicted that adding ZnO is one of reasonable reasons for improvement the mechanical properties of the composite solder (Fig. 5).
(a)
SbSn
Sn
Sb Sn
107
+
3.3. Mechanical properties 3.3.1. Tensile stress–strain response Figs. 6(a–d) and 7(a–d) represent the typical uniaxial tensile curves for the SSC505 and SSCZnO composite solder at different temperatures and various strain rates. It was observed that, the stress levels shifted toward higher values with increasing the strain rate and/or decreasing the testing temperature. Worthy of notice is that, the flow stress continuously reduced with increasing elongation and plain solder alloy exhibited higher ductility than composite solder alloy. Generally, during plastic deformation solder alloys experience simultaneous work hardening and dynamic recovery which have opposite effects on the plastic deformation. Such behavior may be assigned to the rise of ε̇ that creates more dislocation forests through solder lattice space especially at lower deformation temperature [33–35]. On the other hand, with increasing the testing temperature the dislocation annihilation takes place more quickly than dislocation generation that is weakening the hardening. Meanwhile, increasing the strain rate shrunk the time of the dynamic recovery which increases the stress level [12,16,35]. Therefore, the combined effects of both factors reflect the behavior of stress–strain curves.
Sn Sn
0
1
2
Sb Sn Sn
3
4
5
6
7
8
9
10
Energy (keV)
(b) Sn
Cu 6Sn 5
+
Sn
Cu
Sn Sn Sn
0
1
2
3
4
5
Cu
6
7
8
Cu
9
10
Energy (kev) Fig. 5. High-magnification FE-SEM micrographs with corresponding EDS of IMC of (a) SbSn (b) Cu6Sn5.
growth of IMCs both molten alloys are solidified at the same cooling rate of 10 °C/s. in addition, twenty randomly positions selected to precisely determine the size and morphology of composed IMCs. Fig. 3a and b depicts the microstructure of the SSC505 solder that composed of three types of precipitates with different morphologies. The first phase is large β-Sn grains which peppered with isolated white round particles of SbSn IMC. The other phase is coarsening scallop shaped of Cu6Sn5 IMC that decorates the grey network-like eutectic region of Sn–Sb–Cu. From EDS analysis the bright nodules in Fig. 5 are identified as SbSn IMC with an average size of 2.8 70.5 μm and the large gray platelets forms are detected as Cu6Sn5 IMC with an average size of 14.2 7 0.6 μm. Worthy of notice is that, when ZnO nanoparticles incorporated into the plain solder alloy, a remarkable decrease was observed in the average size of IMCs (see Fig. 4a and b). These observations can be explained by the theory of heterogeneous nucleation and the theory of adsorption of the surface active material [30–35]. Hence, the increase of adsorption of elements or oxides (e.g. ZrO2, ZnO, SnO2 and TiO2) could decrease the surface energy and reduced the sizes
3.3.2. Effect of temperature and strain rate on tensile parameters. The effect of strain rate ε̇ at various testing temperature on the UTS and sy are plotted in Figs. 8a, b and 9a, b for plain and composite solder alloys, respectively. It was noted that the UTS and sy of both solders are strongly affected by the variation of ε̇, T and incorporation of ZnO nanoparticles. The values of UTS and sy decrease with raising the testing temperature and/or reducing the strain rate. These variations can be understood by considering the plastic deformation as thermally activated process and rate dependent of stress-assisted. Since, the dislocations have more mobility if thermal energy is increased and could overcome the obstacles through β-Sn matrix [36,37]. Hence, raising the temperature promotes the arrangement of complex dislocation network into simple one. Additionally, at high strain rate, the UTS and sy are increased due to limited time of the dislocation motion which makes dense pinning locations and more harden defects. The strengthening mechanism of the composite solder could be explained in terms of harden ZnO nanoparticles and finer IMCs which distributed within eutectic regions. They act as pinning centers which inhibited the mobility of dislocation that concentrated around grain boundaries [8,34,35]. Furthermore, more defects have been generated with different slipping planes and various orientations. Therefore, similar sign of successive dislocation would repel and accumulate in the domains of β-Sn grains. Additionally, the massive slipping dislocations act as hard blocked web which is consider as one of the reasons for the strengthen mechanism of composite solder. Based on image analysis program and quantitative calculation, the particle size of IMCs were estimated using several SEM images for both solder alloys that annealed 3 h at different temperatures (50, 75, 100 and 125 °C). Zener pinning equation [38,39] was applied to evaluate the pinning stress that inhibited the growth of β-Sn grains due to existence of finer IMCs and ZnO nanoparticles.
108
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
Fig. 6. Stress–strain curves plot the strain rate effect at different testing temperatures (a) 50 °C, (b)75 °C, (c) 100 °C and (d) 125 °C for SSC505 plain solder alloy.
σP =
3f γGB d
(1)
where f is the particle volume fraction, d is the particle radius and γGB is the grain boundary energy of Sn (γGB ¼0.425 J/m2) [1,26]. The pinning stress sp exerted at different annealing temperatures were calculated and recorded in Table 3. It is apparent that, the pinning stress values sp of composite solder alloy are greater than plain solder alloy due to the existence of finer IMCs. 3.3.3. Effect of temperature on stress exponent. Fig. 10a and b shows the double-logarithmic relation between UTS and ε̇ for both alloys at different temperatures. A clear linear relationship is observed; this means that the relationship obeys [34];
ε̇ = C σ
n
(2)
where s is UTS, n is the stress exponent, and C is a material constant. The n values calculated from slope of double-logarithmic relation. Fig. 10c summarized the obtained n values for plain and composite solders. These results illustrate that, the n values decrease with increasing temperature. Moreover, the values of n rapidly decreases for SSCZnO composite solder but remains relatively stable for SSC505 solder with raising the tested temperature.
In fact, the variation of n values with temperature is attributed to the instability of the microstructure of SSCZnO composite solder. It can be deduced that, the plain solder is higher resistance to necking and more thermal stable than composite solder. 3.3.4. Activation energy of plastic tensile deformation. According to the deformation of polycrystalline materials theory, at T /Tm ≥ 0.5, the plastic deformation is predominated by different mechanisms which are associated with different values of stress exponent n and activation energy Q [33,34]. The combined effects of strain rate ε̇, applied stress s and temperature T on the deformation process can be modeled by Norton–Dorn equation [33];
ε ̇ = = A σ n exp (−Q /RT )
(3)
where A is a constant, R is the universal gas constant and s is the ultimate tensile stress. The Q value was calculated by the following Eq. (4):
⎡ ∂(ln ε)̇ ⎤ ⎡ ∂ ln σ ⎤ Q=⎢ ⎥ R ⎥ ⎢ ⎣ ∂ ln σ ⎦T ⎣ ∂(1/T ) ⎦ε̇
(4)
The values of the first term of the right hand side of Eq. (4) evaluating the n values that determined from plotting relationship
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
109
Fig. 7. Stress–strain curves plot the strain rate effect at different testing temperatures (a) 50 °C, (b)75 °C, (c) 100 °C and 125 °C for SSC-ZnO composite solder alloy.
of log ε̇ log sUTS at constant temperature. In addition the Q was calculated from the ln sUTS 1000/T relation that plotted in Fig. 11a and b. The Q values for plain and composite solder exhibit strong dependence on addition of ZnO and variation of ε̇ (see Fig.11c). Additionally, the average activation energies of SSCZnO and SSC505 are 59 and 57 kJ/mol [ 0.6 of Qsn] respectively. The Q values of plain and composite solder are less than those of lattice self-diffusion of β-Sn [QLSD ¼102 kJ/mol]. According to the values of n and Q at high strain rate and/or low temperature, the dominant deformation mechanism is rate controlling mechanism especially dislocation climb which controlled by lattice self-diffusion. Meanwhile, at high tested temperature, the grain boundary diffusion accompanied with dislocation-pipe diffusion could be considered as deformation mechanisms for plain and composite solder alloys [Q of dislocation-pipe diffusion (QDPD) is about 0.6 QLSD] [26]. The obtained Q values are agreed with the activation energy of Sn–5Sb–0.7Cu and Sn–5Sb–1.5Cu (53.4 and 73 kJ/mol), respectively [16,26 ]. From Fig. 11c it is clear that, abrupt change in the Q value was observed for the SSCZnO composite solder with variation of strain rates. Additionally Q value of SSC505 plain solder is smaller than SSCZnO composite solder alloy at low strain rate which implying that the microstructure of the SSC505 solder alloy is highly
sensitive to imported thermal energy. As a result, the dynamic recrystallization is easier to be excited where the energy barrier is lowered. Therefore, the ability of atom to diffuse through the grain boundary is weaker. 3.3.5. Strengthening mechanisms in SSC-ZnO composite solder The increase in the tensile yield stress (sYS) and ultimate strength (UTS) of SSC-ZnO composite solder alloy can be attributed to different strengthen mechanisms of harden reinforcement ZnO nanoparticles as well as finer IMCs in β-Sn matrix. This strengthen behavior can be rendered to one or more of the following effects: (i) grain refinement; (ii) formation of internal thermal stress due to due to different CTE values between the Sn matrix and ZnO nanoparticles; (iii) Orowan strengthening mechanism; (iv) effective load transfer between the matrix and reinforcement nanoparticles; and (v) hardening due to the strain misfit between ingredients of composite solder [40–42]. The contributions to the increase in the yield strength of the composites by various strengthening mechanisms could be described theoretically by the following equation [42].
σCYS = σm + Δσ
(5a)
110
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
Fig. 8. Show the dependence of ultimate tensile strength (UTS) on strain rate at different testing temperatures for (a) SSC505 plain solder and (b) SSC-ZnO composite solder alloy.
σCYS = σm +
( Δσgs )2 + ( ΔσCTE )2 + ( ΔσOrowan )2
(5b)
where sCYS and sm are yield stress of (SSC-ZnO) composite solder and yield stress of matrix (SSC505), respectively. Δs is increase in yield stress in composite solder, Δsgs is grain size strengthening, Δ sCTE is dislocation strengthening and ΔsOrowan is dispersion strengthening, which can be written as [40,43]:
Δσgs = k D−1/2
(6)
ΔσCTE = α G m b ρ
(7)
where
ρ=
ρ is dislocation density [42] (8)
0.13 G m b d ln λ 2b
(9)
and
λ=d
(
λ is the interparticle spacing 3
1/2Vp − 1
)
Table 3 Average of particles size of IMC (d), particles volume fraction (f) and Zener pinning stress (spin) estimated at different annealing temperature. Annealing temperature (°C)
SSC505
SSCZnO
d (μm)
f
spin (kPa) d (μm)
f
50 75 100 125
15.54 7 0.03 16.747 0.04 17.95 7 0.03 19.23 7 0.03
0.42 0.53 0.67 0.89
41.84 41.12 39.78 37.79
0.67 102.31 0.68 83.01 0.64 65.07 0.68 61.71
8.357 0.02 10.46 7 0.04 12.54 7 0.03 14.05 7 0.04
spin (kPa)
valued in Table 4.
12 (αm − αp )(Tprocess − Ttest ) Vp bd (1 − Vp )
ΔσOrowan =
Fig. 9. Shows the dependence of yield stress on strain rate at different testing temperatures for (a) SSC505 plain solder and (b) SSC-ZnO composite solder alloy.
(10)
The mentioned parameters in these equations are defined and
3.3.5.1. Grain size refinement contribution on the yield strength of composite solder. The influence of grain size on the mechanical properties is complex since the grain boundaries may either act as obstacles to dislocation slip (strengthening effect) or provide a positive contribution to the deformation of the material (softening effect). However, the grain size refinement was reported in our previous study [40]. It was illustrated that, the refinement in grain size arises from the presence of reinforcing ZnO nanoparticles which act as pinners' to grain boundaries [8,33–35]. The increase in sYS due grain size strengthening
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
111
Fig. 10. (a–c) Show the double-logarithmic relation between ultimate tensile strength and ε̇ strain rate at different testing temperatures for (a) SSC505 plain solder and (b) SSCZnO composite solder. (c) The dependence of calculated stress exponent on the tested temperature.
can be evaluated by Hall–Petch Eq. (6) and the results at different testing temperatures are listed in Table 6. 3.3.5.2. Effect of thermal expansion mismatch on yield strength. The coefficient of thermal expansion (CTE) mismatch between the Sn matrix and ZnO nanoparticles lead to an increase in thermal dislocation density (ρth) around the reinforcement particles during cooling from elevated processing temperature. The thermal stresses around the nanoparticles would be large enough to induce plastic deformation in the matrix near the interface regions [26,44]. Increase in yield stress due thermal CTE mismatch (ΔsCTE) which are created from the relaxation of thermal expansion mismatch of Sn matrix and ZnO nanoparticles is calculated at different testing temperatures from Eqs. (7) and (8). These results are summarized in Tables 5 and 6. 3.3.5.3. Orowan strengthening. Owing to the presence of dispersed hard ZnO nanoparticles in metal matrix, dislocation loops form as dislocation lines bow and bypass the particles whilst the finer and softer precipitated particles could be sheared [40,41]. Furthermore, the interaction between these dislocations and harden nanoparticles resist the motion of the dislocations, leading to bending of the dislocations between the nano-sized particles. The accumulated dislocations generate a back stress, which could prevent
further dislocation migration [26,43–45]. The effect of this process on sCYS of the material is expressed by Orowan strengthening mechanism (sOrowan) that can be estimated at different temperatures from Eqs. (9) and (10) and results listed in Table 6. The contributions of different strengthening mechanisms to the yield strength of the composite solder were calculated based on the data given in Tables 4 and 5 and using Eqs. (5)–(10). The results are summarized in Table 6, it can be concluded that, at room temperature, the calculated value of sCYS is estimated to be 80.0 MPa. This is nearly close to the experimental value 73.1 MPa which determined from the tensile stress–strain curves data in the pervious report [8]. A complete comparison of the experimental and calculated results in sCYS achieved at all test temperatures is given in Fig. 12. It is evident that as the temperature increases, the achieved strengthening decreases within the testing temperature range. The observed decrement is mainly due to the weakening effect of mismatch strain. This is because the non-coarsening ZnO nanoparticles have a high degree of thermal stability, and thus, their Orowan strengthening is not affected by the test temperature. In general, there is an acceptable agreement between the experimental and calculated values for the achieved composite strengthening. This may reflect the capability of the employed model in the prediction of the increments in the yield stress and ultimate tensile strength.
112
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
Fig. 11. (a–c) Plot the linear relation between ln(sUTS) and 1000/T to calculate the activation energy (Q) for (a) SSC505 plain solder and (b) SSCZnO composite solder. (c) The dependence of calculated activation energy on the stress exponent.
Table 4 Definition and values of the parameters used in Eqs. (6)–(10). Parameters Definition k D α b d Vp αm αp
Value
Locking parameter Average grain size of composite solder (SSC-ZnO) Constant Burger vector Average diameter of ZnO nanoparticles Volume friction of ZnO nanoparticles CTE of Sn matrix CTE of ZnO nanoparticles
Ref. 1/2
0.04 MPa m 70 μm
[26], [8],
1.25 0.3 nm 66 nm 0.005 27.67 10 6 °C 1 3.41 10 6 °C 1
[26], [26], [8], [8], [26], [8],
Table 6 Calculated contributions of different strengthening mechanisms to the yield stress (ΔsYS) of SSC-ZnO composite solder alloy at different temperatures. Temperature (°C)
Δsgs (MPa)
ΔsCTE (MPa)
ΔsOrowan (MPa)
ΔsYS (MPa)
25 50 75 100 125
4.78 4.47 4.04 3.78 3.27
12.5 10.4 8.5 6.2 4.6
7.48 6.79 6.16 5.13 4.58
15.3 13.2 11.3 8.9 7.3
4. Conclusions
Table 5 Calculated values of dislocation density (ρth) at different temperatures by using the shear modulus of composite solder (Gm) and (ΔT) difference in temperature. Temperature (°C)
Gm (GPa)
ΔT ¼ [Tprocess–TTest] (°C)
ρth 1012 (m 2)
25 50 75 100 125
20.1 18.3 16.6 13.8 12.3
155 130 105 80 55
11.10 9.25 7.47 5.69 3.91
Effect of nano-sized ZnO particles on the microstructure and tensile properties of Sn–5 wt% Sb–0.5 wt% Cu (SSC505) solder alloy was studied. Some important conclusions are summarized in the following points. 1. Microstructure investigations revealed that addition of nanosized ZnO particles to SSC505 solder inhibited the growth of the grain size as well as the IMCs which reinforced the strength of the plain solder alloy. Moreover, the values of pinning stress of composite solder alloy is greater than plain solder alloy due to the existence of finer and higher volume fraction of IMCs.
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
Calculated Experimental
80 70
Yield Stress (MPa)
60 50 40 30 20 10 0 0
25
50
75
100
125
150
o
Temperature C Fig. 12. Exhibits the comparison of experimental and calculated values of yield stress of SSC-ZnO composite solder at different testing temperatures.
2. Tensile tests indicated that addition of nano-sized ZnO particles increases the UTS and sy of the SSC505 plain solder. In addition, the UTS and sy increase with increasing strain rate and/or decreasing temperature. These variations can be understood by considering the plastic deformation as thermally activated process and rate dependent of stress-assisted. 3. The strengthening mechanism of the composite solder could be explained in terms of harden ZnO nanoparticles and finer IMCs which distributed within eutectic regions because they act as pinning centers which inhibited the mobility of dislocation that concentrated around grain boundaries. 4. According to the obtained stress exponents and activation energies values, it is proposed that the dominant deformation mechanism in both solders is rate controlling mechanism especially dislocation climb which controlled by lattice selfdiffusion. Meanwhile, at high tested temperature, the grain boundary diffusion accompanied with dislocation-pipe diffusion could be considered as deformation mechanism.
Reference [1] M. Abtewa, G. Selvaduray, Lead-free Solders in Microelectronics, Mater. Sci. Eng. R 27 (2000) 95–141. [2] J. Shen, Y.C. Chan, Research advances in nano-composite solders, Microelectron. Reliab. 49 (2009) 223–234. [3] F. Guo, Composite lead-free electronic solders, J. Mater. Sci.: Mater. Electron. 18 (2007) 129–145. [4] H. Mavoori, S. Jin, New, creep-resistant, low melting point solders with ultrafine oxide dispersions, J. Electron. Mater. 27 (11) (1998) 1216–1222. [5] H. Mavoori, A.G. Ramirez, S. Jin, Lead-free universal solders for optical and electronic devices, J. Electron. Mater. 31 (11) (2002) 1160–1165. [6] G.S. Zhang, H.Y. Jing, L.Y. Xua, J. Wei, Y.D. Han, Creep behavior of eutectic 80Au/ 20Sn solder alloy, J. Alloy. Compd. 476 (2009) 138–141. [7] S. Kang, A. Sarkhel, Lead (Pb)-free solders for electronic packaging, J. Electron. Mater. 23 (8) (1994) 701–707. [8] A.N. Fouda, E.A. Eid, Influence of ZnO nano-particles addition on thermal analysis microstructure evolution and tensile behavior of Sn–5.0 wt% Sb– 0.5 wt% Cu lead-free solder alloy, Mater. Sci. Eng. A 632 (2015) 82–87. [9] A.R. Geranmayeh, G. Nayyeri, R. Mahmudi, Microstructure and impression creep behavior of lead-free Sn–5Sb solder alloy containing Bi and Ag, Mater. Sci. Eng. A 547 (2012) 110–119. [10] A.A. El-Daly, Y. Swilem, A.E. Hammad, Creep properties of Sn–Sb based leadfree solder alloys, J. Alloy. Compd. 471 (2009) 98–104. [11] A.R. Geranmayeh, R. Mahmudi, Power law indentation creep of Sn–5% Sb solder alloy, J. Mater. Sci. 40 (2005) 3361–3366. [12] M.M. EL-Bahay, M.E. EL Mossalamy, M. Mahdy, A.A. Bahgat, Study of the mechanical and thermal properties of Sn–5 wt% Sb solder alloy at two
113
annealing temperatures, Phys. Status Solidi A 198 (1) (2003) 76–90. [13] S.W. Chen, P.Y. Chen, C.H. Wang, Lowering of Sn–Sb alloy melting points caused by substrate dissolution, J. Electron. Mater. 35 (11) (2006) 1982–1985. [14] M.J. Esfandyarpour, R. Mahmudi, Microstructure and tensile behavior of Sn– 5Sb lead-free solder alloy containing Bi and Cu, Mater. Sci. Eng. A 530 (2011) 402–410. [15] E.P. Wood, K.L. Nimno, In search of new lead-free electronic solders, J. Electron. Mater. 23 (8) (1994) 709–713. [16] A.A. El-Daly, A. Fawzy, A.Z. Mohamad, A.M. El-Taher, Microstructural evolution and tensile properties of Sn–5Sb solder alloy containing small amount of Ag and Cu, J. Alloy. Compd. 509 (2011) 4574–4582. [17] A.A. El-Daly, A.Z. Mohamad, A. Fawzy, A.M. El-Taher, Creep behavior of nearperitectic Sn–5Sb solders containing small amount of Ag and Cu, Mater. Sci. Eng. A 528 (2011) 1055–1062. [18] F. Tai, F. Guo, M.T. Han, Z.D. Xia, Y.P. Lei, Y.W. Shi, Creep and thermo-mechanical fatigue properties of in-situ Cu6Sn5 reinforced lead-free composite solder, Mater. Sci. Eng. A 6 (2010) 3335–3342. [19] H.Y. Lee, J.G. Duh, Morphological transition of interfacial Ni3Sn4 grains at the Sn–3.5Ag/Ni joint, J. Electron. Mater. 35 (3) (2006) 494–503. [20] S. Choi, J.G. Lee, F. Guo, T.R. Bieler, K.N. Subraman, J.P. Lucas, Creep properties of Sn–Ag solder joints containing intermetallic particles, JOM 53 (6) (2001) 22–26. [21] F. Guo, J. Lee, J.P. Lucas, K.N. Subramanian, T.R. Bieler, Creep properties of eutectic Sn–3.5Ag solder joints reinforced with mechanically incorporated Ni particles, J. Electron. Mater. 30 (9) (2001) 1222–1227. [22] S.M.L. Nai, J. Wei, M. Gupta, Influence of ceramic reinforcements on the wettability and mechanical properties of novel lead-free solder composites, Thin Solid Films 504 (2006) 401–404. [23] P. Liu, P. Yao, J. Liu, Effect of SiC nanoparticle additions on microstructure and microhardness of Sn–Ag–Cu solder alloy, J. Electron. Mater. 37 (6) (2008) 874–879. [24] X. Wang, Y.C. Liu, C. Wei, H.X. Gao, P. Jiang, L.M. Yu, Strengthening mechanism of SiC-particulate reinforced Sn–3.7Ag–0.9Zn lead-free solder, J. Alloy. Compd. 480 (2009) 662–665. [25] A.A. El-Daly, G.S. Al-Ganainy, A. Fawzy, M.J. Younis, Structural characterization and creep resistance of nano-silicon carbide reinforced Sn–1.0Ag–0.5Cu leadfree solder alloy, Mater. Des. 55 (2014) 837–845. [26] A.R. Geranmayeha, R. Mahmudi, M. Kangooie, High-temperature shear strength of lead-free Sn–Sb–Ag/Al2O3 composite solder, Mater. Sci. Eng. A 528 (2011) 3967–3972. [27] L.C. Tsao, S.Y. Chang, Effects of nano-TiO2 additions on thermal analysis, microstructure and tensile properties of Sn–3.5Ag–0.25Cu solder, Mater. Des. 31 (2010) 990–993. [28] J.C. Leong, L.C. Tsao, C.J. Fang, C.P. Chu, Effect of nano-TiO2 addition on the microstructure and bonding strengths of Sn3.5Ag0.5Cu composite solder BGA packages with immersion Sn surface finish, J. Mater. Sci.: Mater. Electron. 22 (2011) 1443–1449. [29] S.Y. Chang, C.C. Jain, T.H. Chuang, L.P. Feng, L.C. Tsao, Effect of addition of TiO2 nanoparticles on the microstructure, microhardness and interfacial reactions of Sn3.5Ag–XCu solder, Mater. Des. 32 (2011) 4720–4727. [30] P. Babaghorbani, S.M.L. Nai, M. Gupta, Development of lead-free Sn–3.5Ag/SnO2 nanocomposite solders, J. Mater. Sci.: Mater. Electron. 20 (2009) 571–576. [31] J. Shen, Y.C. Chan, Effects of ZrO2 nanoparticles on the mechanical properties of Sn–Zn solder joints on Au/Ni/Cu pads, J. Alloy. Compd. 477 (2009) 552–559. [32] J. Shen, Y.C. Liu, Y.J. Han, Y.M. Tian, H.X. Gao, Strengthening effects of ZrO2 nanoparticles on the microstructure and microhardness of Sn–3.5Ag lead-free solder, J. Electron. Mater. 35 (8) (2006) 1672–1679. [33] A.A. El-Daly, T.A. Elmosalami, W.M. Desoky, M.G. El-Shaarawy, A.M. Abdraboh, Tensile deformation behavior and melting property of nano-sized ZnO particles reinforced Sn–3.0Ag–0.5Cu lead-free solder, Mater. Sci. Eng. A 618 (2014) 389–397. [34] A. Fawzy, S.A. Fayek, M. Sobhy, E. Nassr, M.M. Mousa, G. Saad, Effect of ZnO nanoparticles addition on thermal, microstructure and tensile properties of Sn–3.5 Ag–0.5 Cu (SAC355) solder alloy, J. Mater. Sci.: Mater. Electron. 24 (2013) 3210–3218. [35] A. Fawzy, S.A. Fayek, M. Sobhy, E. Nassr, M.M. Mousa, G. Saad, Tensile creep characteristics of Sn–3.5Ag–0.5Cu (SAC355) solder reinforced with nano-metric ZnO particles, Mater. Sci. Eng. A 603 (2014) 1–10. [36] Rodney J. McCabe, M.E. Fine, Creep of tin, Sb-solution-strengthened tin, and SbSn-precipitate-strengthened, Metall. Mater. Trans. A A33 (5) (2002) 1531–1539. [37] Rodney J. McCabe, M.E. Fine, High creep resistance tin-based alloys for soldering applications, J. Electron. Mater. 31 (11) (2002) 1276–1282. [38] M. Aghaie-Khafri, Formability of AA8011 aluminum alloy sheet in homogenized and unhomogenized conditions, J. Mater. Sci. 39 (2004) 6467–6472. [39] F.J. Humphreys, M. Hatherly, Recrystallization and Related Annealing Phenomena, 2nd Edition, Elsevier Ltd., Oxford, UK (2004), p. 114, ISBN: 0 08 044164 5. [40] F.A. Mirza, D.L. Chen, A unified model for the prediction of yield strength in particulate-reinforced metal matrix nanocomposites, Materials 8 (2015) 5138–5153. [41] Q.B. Nguyen, M. Gupta, Enhancing compressive response of AZ31B magnesium
114
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
alloy using alumina nano-particulates, Compos. Sci. Technol. 68 (2008) 2185–2192. [42] H. Asgharzadeh, A. Simchi, H.S. Kim, Hot deformation of ultrafine-grained Al6063/Al2O3 nanocomposites, J. Mater. Sci. 46 (2011) 4994–5001. [43] X.L. Zhong, W.L.E. Wong, M. Gupta, Enhancing strength and ductility of magnesium by integrating it with aluminum nanoparticles, Acta Mater. 55 (2007) 6338–6344.
[44] K. Mohan Kumar, V. Kripesh, Andrew A.O. Tay, Influence of single-wall carbon nano tube addition on the microstructural and tensile properties of Sn–Pb solder alloy, J. Alloy. Compd. 455 (2008) 148–158. [45] Khin Sandar Tun, M. Gupta, Improving mechanical properties of magnesium using nano-yttria reinforcement and microwave assisted powder metallurgy method, Compos. Sci. Technol. 67 (2007) 2657–2664.
Contents lists available at ScienceDirect
Materials Science & Engineering A journal homepage: www.elsevier.com/locate/msea
Effect of adding 0.5 wt% ZnO nanoparticles, temperature and strain rate on tensile properties of Sn–5.0 wt% Sb–0.5 wt% Cu (SSC505) lead free solder alloy E.A. Eid a,n, A.N. Fouda b,c, El-Shazly M. Duraia b,d a
Basic Science Department, Higher Technological Institute, 44629 10th of Ramadan City, Egypt Physics Department, Faculty of Science, Suez-Canal University, 41522 Ismailia, Egypt c Recruitment Department, University of Hail, Hail 2440, Saudi Arabia d Texas State University-San Marcos, Department of Chemistry and Biochemistry, 601 University Dr., San Marcos, TX 78666, USA b
art ic l e i nf o
a b s t r a c t
Article history: Received 18 September 2015 Received in revised form 19 December 2015 Accepted 26 January 2016 Available online 27 January 2016
This study investigates the effect of adding 0.5 wt% ZnO nanoparticles into Sn–5 wt% Sb–0.5 wt% Cu (SSC505) solder alloy on the growth of intermetallic compounds (IMCs) as well as the associated changes of microstructure. It was found that, the morphologies of the IMCs transformed to refinement forms due to the adsorption effect of ZnO nanoparticles. Systematic study of tensile properties was performed for bulk solders over a wide range of strain rates at various temperatures to determine the plastic deformation mechanism. Obviously, the ultimate tensile strength (UTS) and the yield stress (sy) were improved. This can be attributed to reinforcement of ZnO nanoparticles, refined β-Sn grains and IMCs that could obstruct the dislocation slipping. The obtained results are consistent with the prediction of the classic theory of dispersion strengthening. Furthermore, the average activation energy (Q) for plain and composite solders were 57 and 59 kJ/mol, respectively, which close to that of pipe-diffusion mechanism in Sn based solder matrix. & 2016 Elsevier B.V. All rights reserved.
Keywords: Lead-free solder Sn–Sb–Cu alloy Microstructure Composite solder Mechanical properties
1. Introduction The requirements for high reliability and integrity are challenging the solder joints performance, especially under the complicated service environments of thermal and mechanical conditions [1]. Moreover, the miniaturization of solder joints requires the increase of high packaging density (I/O) of electronic components withal better performing. Based on these facts, intensive verves have been dedicated to improve the typical reliability affairs of solder joints [1–3]. However, Pb is toxic, and is banned in many industrial applications. Therefore, the Pb-containing solder alloys are exempted from the production lines of electronic packaging [1–4]. Recently, Sn-based alloys or Pb-free solder (LFS) materials are considered as a promising replacement of Pb-containing solder alloys [1]. Toward this approach, new LFS alloys is prepared to replace high Pb-containing solder alloys [Pb–(10– 5) wt% Sn] that are extensively used in electronic power semiconductor, and optical device packaging, flip-chip packaging, etc. n
Corresponding author. E-mail addresses: [email protected] (E.A. Eid), [email protected] (A.N. Fouda). http://dx.doi.org/10.1016/j.msea.2016.01.081 0921-5093/& 2016 Elsevier B.V. All rights reserved.
[5]. In last decade, Au–20 wt% Sn is considered as the best solder alloy for most applications in optoelectronic packaging, because of its high creep resistance, wettability and good reliability [6]. This solder alloy is expensive and has high melting temperature (280 °C) which could damage the properties of optical fibers and optoelectronics such as lasers, light emitting devices, photodetectors, or waveguide devices [7,8]. Recently, Sn–5Sb alloy is considered as attractive candidate of LFS alloys when compared to Au–20Sn solder alloy. Since, it has low cost and prime mechanical properties among LFS alloys. Additionally, its wettability and tensile properties have been improved by adding ternary or quaternary alloy additions [9–15]. El-Daly et al. reported that, the addition of small amount of Cu (0.7 wt%) to the matrix of Sn–5Sb can depress the melting temperature and enhances the refinement of the IMCs without reducing the ductility of alloys [16,17]. Moreover, high reliability of solder joints is geared by adding nano-size reinforcement particles in matrix solders. Lead free composite solder (LFCS) alloys have been identified as the effective materials to provide higher microstructure stability and better mechanical properties as compared to conventional solders [2–4]. As a result, a large number of studies on LFCS alloys were performed. Generally, LFCS are containing micro or nano sized
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
Table 1 Chemical composition of the solder alloys studied (wt%).
(b)
Solder alloy
ZnO
Sb
Cu
Fe
In
As
Sn
SSC505 SSCZnO
– 0.502
5.024 5.016
0.502 0.504
0.003 0.003
0.002 0.002
0.001 0.001
Bal. Bal.
105
Sn
(a)
Sn Table 2 Tensile testing condition.
Sb Sn
Solder alloy
Strain rate (s 1)
Temperature (°C)
SSC505
5.0 × 10 2 1.0 × 10 3 5.0 × 10 3 1.0 × 10 4
50 75 100 125
SSCZnO
0
Cu O
Zn
1
2
Sb
Sn
3
4
Sn
5
Cu Zn
6
7
8
Zn
9
10
Energy (keV)
(b ) SSC ZnO
•
♣
ZnO(101) ZnO(002)
INTENSITY (arb.units)
♦
Sn SbSn Cu 6 Sn 5 ZnO 2
(a )SSC505
• •
• •
•
♣
♦
30
♣♦
♣ ♦
♦
40
•
•
50
♦• • ♣
60
♦
• • ♣
♦ 70
♣
Fig. 2. (a) FE-SEM micrograph of the SSC-ZnO composite solder to shows the existence nano-sized ZnO particles in solder matrix. (b) EDS of eutectic region of composite solder.
liquidus temperature, yield strength and ultimate tensile strength of LFCS increase significantly with the addition of nano-sized particles. On the other hand, some investigator reported that TiO2, SnO2 and Al2O3 [26–30] nano-oxide particles decompose the microstructure of β-Sn matrix and cause solid-solution hardening. Withal, Shen et al. [30,31] indicated that the addition of ZrO2 nanoparticles to Sn–3.5Ag and Sn–3.5Ag 0.5Cu solder alloy tends to suppress the growth of IMCs and refines the rode-like Ag3Sn IMC in the solder matrix and improve the microhardness as well as mechanical properties. It is worthy mentioned that, the results of research survey display little studies have been reported so far on Sn–Sb–Cu that containing ZnO nano-sized particles [8]. The aim of the current study is characterizing the Sn–5wt% Sb–0.5 wt% Cu (SSC505) plain solder and Sn–5wt% Sb–0.5 wt% Cu–0.5 wt% ZnO (SSC-ZnO) composite solder alloys in terms of as-solidified microstructures with focusing on growth and morphology of IMCs. Since the solder alloys must preserve their mechanical reliability under a myriad of conditions. Therefore, this report investigates the influence of strain rate and temperature on the tensile properties of both solder alloys, to determine the plastic deformation mechanism.
80
2 θ (degree) Fig. 1. XRD profiles of (a) SSC505 solder and (b) SSC-ZnO composite solder alloys.
2. Experimental procedure 2.1. Preparation of samples
particles serve as obstacles for grain growth and retard motion of dislocations which cause strengthen of the solder joint. Guo et al. [3] classified the reinforcement particles into two categories. (i) First category involves adding intermetallic compounds (IMCs) (e.g. Cu6Sn5, Cu3Sn or Ni3Sn4) [18–21]. (ii) Second category includes ceramic or oxide nanoparticles which have low solubility and less diffusivity with solder matrix (e.g. TiB2 [22] SiC [23–25], Al2O3 [26], TiO2 [27–29], SnO2 [30] and ZrO2 [31,32]). El-Daly et al. [33] and Fawzy et al. [34,35] investigated the effect of minor addition of ZnO nanoparticles on the microstructure, thermal property and tensile properties of Sn–Ag–Cu. They reported that the
The Sn–5wt% Sb–0.5 wt% Cu plain solder alloy was prepared from bulk Sn, Sb and Cu rods with high purity. The process of melting was performed in a vacuum furnace at 650 °C for 2 h. Then, the alloy was remelted three times in order to get a homogeneous composition. The composite solder was prepared by mechanically dispersing 0.5 wt% of ZnO nanopowder into the molten SSC505 solder and remelting in vacuum furnace at 650 °C for 2 h, then casted in a steel mold. The chemical composition of the investigated solder alloys is tabulated in Table 1. More details of composite alloys preparation are described elsewhere [8,33–35].
106
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
Fig. 3. FE-SEM micrographs shows of IMC for SSC505 plain solder alloy; (a) low magnification and (b) high magnification.
Fig. 4. FE-SEM micrographs shows of IMC for SSC-ZnO composite solder alloy; (a) low magnification and (b) high magnification.
2.2. Metallographic observation
3. Results and discussion
Scanning electron microscope (SEM) was employed to examine the microstructure of the synthesized alloys. The SEM used in this study was JEOL model JSM-5410, Japan. An energy dispersive spectrometry (EDS) was used to determine the chemical composition of the IMC phases. In addition, phase identification was examined using X-ray diffractometer (XRD) at 40 kV and 20 mA using CuKα radiation (λ ¼0.15406 nm) with diffraction angle (2θ) from 20° to 90° and constant scanning speed of 1° min 1.
3.1. X-ray diffraction (XRD) of SSC505 and SSC-ZnO composite solders
2.3. Tensile testing Tensile tests were conducted using ASTM E8/E8M-13a standard test methods for tensile tension test of metallic materials. A systematic work on tensile test was performed for the two investigated solder alloys at four testing temperatures from 50 °C up to 125 °C under different strain rates (shown in Table 2). Each datum represents an average of four measurements. The sample temperature was monitored using a thermocouple contacting the sample surface.
Fig. 1a and b depicts the XRD profile of the plain and composite solders. The obtained phases are identified by comparing the Bragg peaks with the ASTM standards. Intense peaks of β-Sn rich phase besides small peaks of SbSn and Cu6Sn5 phases have been observed. It is well known that, the dissolved Sb and Cu are precipitated by forming SbSn and Cu6Sn5 IMCs in the Sn matrix during solidification [8,14,16]. Although, the concentration of ZnO nanoparticles is relatively small, the main peaks of ZnO were detected in Fig.1b. Furthermore, the existence of ZnO nanoparticles within solidified solder was confirmed using SEM and EDS analysis as exhibited in Fig. 2. 3.2. Microstructure characterization In order to study the influence of ZnO nanoparticles on the
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
of IMCs of composite solder. Therefore, the smaller β-Sn grains and finer IMCs can increase the massive defects at the grain boundary. Additionally, ZnO at the interface boundaries could be diffused due to the limited solid solubility of ZnO in solder matrix [33–35]. Therefore, it is predicted that adding ZnO is one of reasonable reasons for improvement the mechanical properties of the composite solder (Fig. 5).
(a)
SbSn
Sn
Sb Sn
107
+
3.3. Mechanical properties 3.3.1. Tensile stress–strain response Figs. 6(a–d) and 7(a–d) represent the typical uniaxial tensile curves for the SSC505 and SSCZnO composite solder at different temperatures and various strain rates. It was observed that, the stress levels shifted toward higher values with increasing the strain rate and/or decreasing the testing temperature. Worthy of notice is that, the flow stress continuously reduced with increasing elongation and plain solder alloy exhibited higher ductility than composite solder alloy. Generally, during plastic deformation solder alloys experience simultaneous work hardening and dynamic recovery which have opposite effects on the plastic deformation. Such behavior may be assigned to the rise of ε̇ that creates more dislocation forests through solder lattice space especially at lower deformation temperature [33–35]. On the other hand, with increasing the testing temperature the dislocation annihilation takes place more quickly than dislocation generation that is weakening the hardening. Meanwhile, increasing the strain rate shrunk the time of the dynamic recovery which increases the stress level [12,16,35]. Therefore, the combined effects of both factors reflect the behavior of stress–strain curves.
Sn Sn
0
1
2
Sb Sn Sn
3
4
5
6
7
8
9
10
Energy (keV)
(b) Sn
Cu 6Sn 5
+
Sn
Cu
Sn Sn Sn
0
1
2
3
4
5
Cu
6
7
8
Cu
9
10
Energy (kev) Fig. 5. High-magnification FE-SEM micrographs with corresponding EDS of IMC of (a) SbSn (b) Cu6Sn5.
growth of IMCs both molten alloys are solidified at the same cooling rate of 10 °C/s. in addition, twenty randomly positions selected to precisely determine the size and morphology of composed IMCs. Fig. 3a and b depicts the microstructure of the SSC505 solder that composed of three types of precipitates with different morphologies. The first phase is large β-Sn grains which peppered with isolated white round particles of SbSn IMC. The other phase is coarsening scallop shaped of Cu6Sn5 IMC that decorates the grey network-like eutectic region of Sn–Sb–Cu. From EDS analysis the bright nodules in Fig. 5 are identified as SbSn IMC with an average size of 2.8 70.5 μm and the large gray platelets forms are detected as Cu6Sn5 IMC with an average size of 14.2 7 0.6 μm. Worthy of notice is that, when ZnO nanoparticles incorporated into the plain solder alloy, a remarkable decrease was observed in the average size of IMCs (see Fig. 4a and b). These observations can be explained by the theory of heterogeneous nucleation and the theory of adsorption of the surface active material [30–35]. Hence, the increase of adsorption of elements or oxides (e.g. ZrO2, ZnO, SnO2 and TiO2) could decrease the surface energy and reduced the sizes
3.3.2. Effect of temperature and strain rate on tensile parameters. The effect of strain rate ε̇ at various testing temperature on the UTS and sy are plotted in Figs. 8a, b and 9a, b for plain and composite solder alloys, respectively. It was noted that the UTS and sy of both solders are strongly affected by the variation of ε̇, T and incorporation of ZnO nanoparticles. The values of UTS and sy decrease with raising the testing temperature and/or reducing the strain rate. These variations can be understood by considering the plastic deformation as thermally activated process and rate dependent of stress-assisted. Since, the dislocations have more mobility if thermal energy is increased and could overcome the obstacles through β-Sn matrix [36,37]. Hence, raising the temperature promotes the arrangement of complex dislocation network into simple one. Additionally, at high strain rate, the UTS and sy are increased due to limited time of the dislocation motion which makes dense pinning locations and more harden defects. The strengthening mechanism of the composite solder could be explained in terms of harden ZnO nanoparticles and finer IMCs which distributed within eutectic regions. They act as pinning centers which inhibited the mobility of dislocation that concentrated around grain boundaries [8,34,35]. Furthermore, more defects have been generated with different slipping planes and various orientations. Therefore, similar sign of successive dislocation would repel and accumulate in the domains of β-Sn grains. Additionally, the massive slipping dislocations act as hard blocked web which is consider as one of the reasons for the strengthen mechanism of composite solder. Based on image analysis program and quantitative calculation, the particle size of IMCs were estimated using several SEM images for both solder alloys that annealed 3 h at different temperatures (50, 75, 100 and 125 °C). Zener pinning equation [38,39] was applied to evaluate the pinning stress that inhibited the growth of β-Sn grains due to existence of finer IMCs and ZnO nanoparticles.
108
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
Fig. 6. Stress–strain curves plot the strain rate effect at different testing temperatures (a) 50 °C, (b)75 °C, (c) 100 °C and (d) 125 °C for SSC505 plain solder alloy.
σP =
3f γGB d
(1)
where f is the particle volume fraction, d is the particle radius and γGB is the grain boundary energy of Sn (γGB ¼0.425 J/m2) [1,26]. The pinning stress sp exerted at different annealing temperatures were calculated and recorded in Table 3. It is apparent that, the pinning stress values sp of composite solder alloy are greater than plain solder alloy due to the existence of finer IMCs. 3.3.3. Effect of temperature on stress exponent. Fig. 10a and b shows the double-logarithmic relation between UTS and ε̇ for both alloys at different temperatures. A clear linear relationship is observed; this means that the relationship obeys [34];
ε̇ = C σ
n
(2)
where s is UTS, n is the stress exponent, and C is a material constant. The n values calculated from slope of double-logarithmic relation. Fig. 10c summarized the obtained n values for plain and composite solders. These results illustrate that, the n values decrease with increasing temperature. Moreover, the values of n rapidly decreases for SSCZnO composite solder but remains relatively stable for SSC505 solder with raising the tested temperature.
In fact, the variation of n values with temperature is attributed to the instability of the microstructure of SSCZnO composite solder. It can be deduced that, the plain solder is higher resistance to necking and more thermal stable than composite solder. 3.3.4. Activation energy of plastic tensile deformation. According to the deformation of polycrystalline materials theory, at T /Tm ≥ 0.5, the plastic deformation is predominated by different mechanisms which are associated with different values of stress exponent n and activation energy Q [33,34]. The combined effects of strain rate ε̇, applied stress s and temperature T on the deformation process can be modeled by Norton–Dorn equation [33];
ε ̇ = = A σ n exp (−Q /RT )
(3)
where A is a constant, R is the universal gas constant and s is the ultimate tensile stress. The Q value was calculated by the following Eq. (4):
⎡ ∂(ln ε)̇ ⎤ ⎡ ∂ ln σ ⎤ Q=⎢ ⎥ R ⎥ ⎢ ⎣ ∂ ln σ ⎦T ⎣ ∂(1/T ) ⎦ε̇
(4)
The values of the first term of the right hand side of Eq. (4) evaluating the n values that determined from plotting relationship
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
109
Fig. 7. Stress–strain curves plot the strain rate effect at different testing temperatures (a) 50 °C, (b)75 °C, (c) 100 °C and 125 °C for SSC-ZnO composite solder alloy.
of log ε̇ log sUTS at constant temperature. In addition the Q was calculated from the ln sUTS 1000/T relation that plotted in Fig. 11a and b. The Q values for plain and composite solder exhibit strong dependence on addition of ZnO and variation of ε̇ (see Fig.11c). Additionally, the average activation energies of SSCZnO and SSC505 are 59 and 57 kJ/mol [ 0.6 of Qsn] respectively. The Q values of plain and composite solder are less than those of lattice self-diffusion of β-Sn [QLSD ¼102 kJ/mol]. According to the values of n and Q at high strain rate and/or low temperature, the dominant deformation mechanism is rate controlling mechanism especially dislocation climb which controlled by lattice self-diffusion. Meanwhile, at high tested temperature, the grain boundary diffusion accompanied with dislocation-pipe diffusion could be considered as deformation mechanisms for plain and composite solder alloys [Q of dislocation-pipe diffusion (QDPD) is about 0.6 QLSD] [26]. The obtained Q values are agreed with the activation energy of Sn–5Sb–0.7Cu and Sn–5Sb–1.5Cu (53.4 and 73 kJ/mol), respectively [16,26 ]. From Fig. 11c it is clear that, abrupt change in the Q value was observed for the SSCZnO composite solder with variation of strain rates. Additionally Q value of SSC505 plain solder is smaller than SSCZnO composite solder alloy at low strain rate which implying that the microstructure of the SSC505 solder alloy is highly
sensitive to imported thermal energy. As a result, the dynamic recrystallization is easier to be excited where the energy barrier is lowered. Therefore, the ability of atom to diffuse through the grain boundary is weaker. 3.3.5. Strengthening mechanisms in SSC-ZnO composite solder The increase in the tensile yield stress (sYS) and ultimate strength (UTS) of SSC-ZnO composite solder alloy can be attributed to different strengthen mechanisms of harden reinforcement ZnO nanoparticles as well as finer IMCs in β-Sn matrix. This strengthen behavior can be rendered to one or more of the following effects: (i) grain refinement; (ii) formation of internal thermal stress due to due to different CTE values between the Sn matrix and ZnO nanoparticles; (iii) Orowan strengthening mechanism; (iv) effective load transfer between the matrix and reinforcement nanoparticles; and (v) hardening due to the strain misfit between ingredients of composite solder [40–42]. The contributions to the increase in the yield strength of the composites by various strengthening mechanisms could be described theoretically by the following equation [42].
σCYS = σm + Δσ
(5a)
110
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
Fig. 8. Show the dependence of ultimate tensile strength (UTS) on strain rate at different testing temperatures for (a) SSC505 plain solder and (b) SSC-ZnO composite solder alloy.
σCYS = σm +
( Δσgs )2 + ( ΔσCTE )2 + ( ΔσOrowan )2
(5b)
where sCYS and sm are yield stress of (SSC-ZnO) composite solder and yield stress of matrix (SSC505), respectively. Δs is increase in yield stress in composite solder, Δsgs is grain size strengthening, Δ sCTE is dislocation strengthening and ΔsOrowan is dispersion strengthening, which can be written as [40,43]:
Δσgs = k D−1/2
(6)
ΔσCTE = α G m b ρ
(7)
where
ρ=
ρ is dislocation density [42] (8)
0.13 G m b d ln λ 2b
(9)
and
λ=d
(
λ is the interparticle spacing 3
1/2Vp − 1
)
Table 3 Average of particles size of IMC (d), particles volume fraction (f) and Zener pinning stress (spin) estimated at different annealing temperature. Annealing temperature (°C)
SSC505
SSCZnO
d (μm)
f
spin (kPa) d (μm)
f
50 75 100 125
15.54 7 0.03 16.747 0.04 17.95 7 0.03 19.23 7 0.03
0.42 0.53 0.67 0.89
41.84 41.12 39.78 37.79
0.67 102.31 0.68 83.01 0.64 65.07 0.68 61.71
8.357 0.02 10.46 7 0.04 12.54 7 0.03 14.05 7 0.04
spin (kPa)
valued in Table 4.
12 (αm − αp )(Tprocess − Ttest ) Vp bd (1 − Vp )
ΔσOrowan =
Fig. 9. Shows the dependence of yield stress on strain rate at different testing temperatures for (a) SSC505 plain solder and (b) SSC-ZnO composite solder alloy.
(10)
The mentioned parameters in these equations are defined and
3.3.5.1. Grain size refinement contribution on the yield strength of composite solder. The influence of grain size on the mechanical properties is complex since the grain boundaries may either act as obstacles to dislocation slip (strengthening effect) or provide a positive contribution to the deformation of the material (softening effect). However, the grain size refinement was reported in our previous study [40]. It was illustrated that, the refinement in grain size arises from the presence of reinforcing ZnO nanoparticles which act as pinners' to grain boundaries [8,33–35]. The increase in sYS due grain size strengthening
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
111
Fig. 10. (a–c) Show the double-logarithmic relation between ultimate tensile strength and ε̇ strain rate at different testing temperatures for (a) SSC505 plain solder and (b) SSCZnO composite solder. (c) The dependence of calculated stress exponent on the tested temperature.
can be evaluated by Hall–Petch Eq. (6) and the results at different testing temperatures are listed in Table 6. 3.3.5.2. Effect of thermal expansion mismatch on yield strength. The coefficient of thermal expansion (CTE) mismatch between the Sn matrix and ZnO nanoparticles lead to an increase in thermal dislocation density (ρth) around the reinforcement particles during cooling from elevated processing temperature. The thermal stresses around the nanoparticles would be large enough to induce plastic deformation in the matrix near the interface regions [26,44]. Increase in yield stress due thermal CTE mismatch (ΔsCTE) which are created from the relaxation of thermal expansion mismatch of Sn matrix and ZnO nanoparticles is calculated at different testing temperatures from Eqs. (7) and (8). These results are summarized in Tables 5 and 6. 3.3.5.3. Orowan strengthening. Owing to the presence of dispersed hard ZnO nanoparticles in metal matrix, dislocation loops form as dislocation lines bow and bypass the particles whilst the finer and softer precipitated particles could be sheared [40,41]. Furthermore, the interaction between these dislocations and harden nanoparticles resist the motion of the dislocations, leading to bending of the dislocations between the nano-sized particles. The accumulated dislocations generate a back stress, which could prevent
further dislocation migration [26,43–45]. The effect of this process on sCYS of the material is expressed by Orowan strengthening mechanism (sOrowan) that can be estimated at different temperatures from Eqs. (9) and (10) and results listed in Table 6. The contributions of different strengthening mechanisms to the yield strength of the composite solder were calculated based on the data given in Tables 4 and 5 and using Eqs. (5)–(10). The results are summarized in Table 6, it can be concluded that, at room temperature, the calculated value of sCYS is estimated to be 80.0 MPa. This is nearly close to the experimental value 73.1 MPa which determined from the tensile stress–strain curves data in the pervious report [8]. A complete comparison of the experimental and calculated results in sCYS achieved at all test temperatures is given in Fig. 12. It is evident that as the temperature increases, the achieved strengthening decreases within the testing temperature range. The observed decrement is mainly due to the weakening effect of mismatch strain. This is because the non-coarsening ZnO nanoparticles have a high degree of thermal stability, and thus, their Orowan strengthening is not affected by the test temperature. In general, there is an acceptable agreement between the experimental and calculated values for the achieved composite strengthening. This may reflect the capability of the employed model in the prediction of the increments in the yield stress and ultimate tensile strength.
112
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
Fig. 11. (a–c) Plot the linear relation between ln(sUTS) and 1000/T to calculate the activation energy (Q) for (a) SSC505 plain solder and (b) SSCZnO composite solder. (c) The dependence of calculated activation energy on the stress exponent.
Table 4 Definition and values of the parameters used in Eqs. (6)–(10). Parameters Definition k D α b d Vp αm αp
Value
Locking parameter Average grain size of composite solder (SSC-ZnO) Constant Burger vector Average diameter of ZnO nanoparticles Volume friction of ZnO nanoparticles CTE of Sn matrix CTE of ZnO nanoparticles
Ref. 1/2
0.04 MPa m 70 μm
[26], [8],
1.25 0.3 nm 66 nm 0.005 27.67 10 6 °C 1 3.41 10 6 °C 1
[26], [26], [8], [8], [26], [8],
Table 6 Calculated contributions of different strengthening mechanisms to the yield stress (ΔsYS) of SSC-ZnO composite solder alloy at different temperatures. Temperature (°C)
Δsgs (MPa)
ΔsCTE (MPa)
ΔsOrowan (MPa)
ΔsYS (MPa)
25 50 75 100 125
4.78 4.47 4.04 3.78 3.27
12.5 10.4 8.5 6.2 4.6
7.48 6.79 6.16 5.13 4.58
15.3 13.2 11.3 8.9 7.3
4. Conclusions
Table 5 Calculated values of dislocation density (ρth) at different temperatures by using the shear modulus of composite solder (Gm) and (ΔT) difference in temperature. Temperature (°C)
Gm (GPa)
ΔT ¼ [Tprocess–TTest] (°C)
ρth 1012 (m 2)
25 50 75 100 125
20.1 18.3 16.6 13.8 12.3
155 130 105 80 55
11.10 9.25 7.47 5.69 3.91
Effect of nano-sized ZnO particles on the microstructure and tensile properties of Sn–5 wt% Sb–0.5 wt% Cu (SSC505) solder alloy was studied. Some important conclusions are summarized in the following points. 1. Microstructure investigations revealed that addition of nanosized ZnO particles to SSC505 solder inhibited the growth of the grain size as well as the IMCs which reinforced the strength of the plain solder alloy. Moreover, the values of pinning stress of composite solder alloy is greater than plain solder alloy due to the existence of finer and higher volume fraction of IMCs.
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
Calculated Experimental
80 70
Yield Stress (MPa)
60 50 40 30 20 10 0 0
25
50
75
100
125
150
o
Temperature C Fig. 12. Exhibits the comparison of experimental and calculated values of yield stress of SSC-ZnO composite solder at different testing temperatures.
2. Tensile tests indicated that addition of nano-sized ZnO particles increases the UTS and sy of the SSC505 plain solder. In addition, the UTS and sy increase with increasing strain rate and/or decreasing temperature. These variations can be understood by considering the plastic deformation as thermally activated process and rate dependent of stress-assisted. 3. The strengthening mechanism of the composite solder could be explained in terms of harden ZnO nanoparticles and finer IMCs which distributed within eutectic regions because they act as pinning centers which inhibited the mobility of dislocation that concentrated around grain boundaries. 4. According to the obtained stress exponents and activation energies values, it is proposed that the dominant deformation mechanism in both solders is rate controlling mechanism especially dislocation climb which controlled by lattice selfdiffusion. Meanwhile, at high tested temperature, the grain boundary diffusion accompanied with dislocation-pipe diffusion could be considered as deformation mechanism.
Reference [1] M. Abtewa, G. Selvaduray, Lead-free Solders in Microelectronics, Mater. Sci. Eng. R 27 (2000) 95–141. [2] J. Shen, Y.C. Chan, Research advances in nano-composite solders, Microelectron. Reliab. 49 (2009) 223–234. [3] F. Guo, Composite lead-free electronic solders, J. Mater. Sci.: Mater. Electron. 18 (2007) 129–145. [4] H. Mavoori, S. Jin, New, creep-resistant, low melting point solders with ultrafine oxide dispersions, J. Electron. Mater. 27 (11) (1998) 1216–1222. [5] H. Mavoori, A.G. Ramirez, S. Jin, Lead-free universal solders for optical and electronic devices, J. Electron. Mater. 31 (11) (2002) 1160–1165. [6] G.S. Zhang, H.Y. Jing, L.Y. Xua, J. Wei, Y.D. Han, Creep behavior of eutectic 80Au/ 20Sn solder alloy, J. Alloy. Compd. 476 (2009) 138–141. [7] S. Kang, A. Sarkhel, Lead (Pb)-free solders for electronic packaging, J. Electron. Mater. 23 (8) (1994) 701–707. [8] A.N. Fouda, E.A. Eid, Influence of ZnO nano-particles addition on thermal analysis microstructure evolution and tensile behavior of Sn–5.0 wt% Sb– 0.5 wt% Cu lead-free solder alloy, Mater. Sci. Eng. A 632 (2015) 82–87. [9] A.R. Geranmayeh, G. Nayyeri, R. Mahmudi, Microstructure and impression creep behavior of lead-free Sn–5Sb solder alloy containing Bi and Ag, Mater. Sci. Eng. A 547 (2012) 110–119. [10] A.A. El-Daly, Y. Swilem, A.E. Hammad, Creep properties of Sn–Sb based leadfree solder alloys, J. Alloy. Compd. 471 (2009) 98–104. [11] A.R. Geranmayeh, R. Mahmudi, Power law indentation creep of Sn–5% Sb solder alloy, J. Mater. Sci. 40 (2005) 3361–3366. [12] M.M. EL-Bahay, M.E. EL Mossalamy, M. Mahdy, A.A. Bahgat, Study of the mechanical and thermal properties of Sn–5 wt% Sb solder alloy at two
113
annealing temperatures, Phys. Status Solidi A 198 (1) (2003) 76–90. [13] S.W. Chen, P.Y. Chen, C.H. Wang, Lowering of Sn–Sb alloy melting points caused by substrate dissolution, J. Electron. Mater. 35 (11) (2006) 1982–1985. [14] M.J. Esfandyarpour, R. Mahmudi, Microstructure and tensile behavior of Sn– 5Sb lead-free solder alloy containing Bi and Cu, Mater. Sci. Eng. A 530 (2011) 402–410. [15] E.P. Wood, K.L. Nimno, In search of new lead-free electronic solders, J. Electron. Mater. 23 (8) (1994) 709–713. [16] A.A. El-Daly, A. Fawzy, A.Z. Mohamad, A.M. El-Taher, Microstructural evolution and tensile properties of Sn–5Sb solder alloy containing small amount of Ag and Cu, J. Alloy. Compd. 509 (2011) 4574–4582. [17] A.A. El-Daly, A.Z. Mohamad, A. Fawzy, A.M. El-Taher, Creep behavior of nearperitectic Sn–5Sb solders containing small amount of Ag and Cu, Mater. Sci. Eng. A 528 (2011) 1055–1062. [18] F. Tai, F. Guo, M.T. Han, Z.D. Xia, Y.P. Lei, Y.W. Shi, Creep and thermo-mechanical fatigue properties of in-situ Cu6Sn5 reinforced lead-free composite solder, Mater. Sci. Eng. A 6 (2010) 3335–3342. [19] H.Y. Lee, J.G. Duh, Morphological transition of interfacial Ni3Sn4 grains at the Sn–3.5Ag/Ni joint, J. Electron. Mater. 35 (3) (2006) 494–503. [20] S. Choi, J.G. Lee, F. Guo, T.R. Bieler, K.N. Subraman, J.P. Lucas, Creep properties of Sn–Ag solder joints containing intermetallic particles, JOM 53 (6) (2001) 22–26. [21] F. Guo, J. Lee, J.P. Lucas, K.N. Subramanian, T.R. Bieler, Creep properties of eutectic Sn–3.5Ag solder joints reinforced with mechanically incorporated Ni particles, J. Electron. Mater. 30 (9) (2001) 1222–1227. [22] S.M.L. Nai, J. Wei, M. Gupta, Influence of ceramic reinforcements on the wettability and mechanical properties of novel lead-free solder composites, Thin Solid Films 504 (2006) 401–404. [23] P. Liu, P. Yao, J. Liu, Effect of SiC nanoparticle additions on microstructure and microhardness of Sn–Ag–Cu solder alloy, J. Electron. Mater. 37 (6) (2008) 874–879. [24] X. Wang, Y.C. Liu, C. Wei, H.X. Gao, P. Jiang, L.M. Yu, Strengthening mechanism of SiC-particulate reinforced Sn–3.7Ag–0.9Zn lead-free solder, J. Alloy. Compd. 480 (2009) 662–665. [25] A.A. El-Daly, G.S. Al-Ganainy, A. Fawzy, M.J. Younis, Structural characterization and creep resistance of nano-silicon carbide reinforced Sn–1.0Ag–0.5Cu leadfree solder alloy, Mater. Des. 55 (2014) 837–845. [26] A.R. Geranmayeha, R. Mahmudi, M. Kangooie, High-temperature shear strength of lead-free Sn–Sb–Ag/Al2O3 composite solder, Mater. Sci. Eng. A 528 (2011) 3967–3972. [27] L.C. Tsao, S.Y. Chang, Effects of nano-TiO2 additions on thermal analysis, microstructure and tensile properties of Sn–3.5Ag–0.25Cu solder, Mater. Des. 31 (2010) 990–993. [28] J.C. Leong, L.C. Tsao, C.J. Fang, C.P. Chu, Effect of nano-TiO2 addition on the microstructure and bonding strengths of Sn3.5Ag0.5Cu composite solder BGA packages with immersion Sn surface finish, J. Mater. Sci.: Mater. Electron. 22 (2011) 1443–1449. [29] S.Y. Chang, C.C. Jain, T.H. Chuang, L.P. Feng, L.C. Tsao, Effect of addition of TiO2 nanoparticles on the microstructure, microhardness and interfacial reactions of Sn3.5Ag–XCu solder, Mater. Des. 32 (2011) 4720–4727. [30] P. Babaghorbani, S.M.L. Nai, M. Gupta, Development of lead-free Sn–3.5Ag/SnO2 nanocomposite solders, J. Mater. Sci.: Mater. Electron. 20 (2009) 571–576. [31] J. Shen, Y.C. Chan, Effects of ZrO2 nanoparticles on the mechanical properties of Sn–Zn solder joints on Au/Ni/Cu pads, J. Alloy. Compd. 477 (2009) 552–559. [32] J. Shen, Y.C. Liu, Y.J. Han, Y.M. Tian, H.X. Gao, Strengthening effects of ZrO2 nanoparticles on the microstructure and microhardness of Sn–3.5Ag lead-free solder, J. Electron. Mater. 35 (8) (2006) 1672–1679. [33] A.A. El-Daly, T.A. Elmosalami, W.M. Desoky, M.G. El-Shaarawy, A.M. Abdraboh, Tensile deformation behavior and melting property of nano-sized ZnO particles reinforced Sn–3.0Ag–0.5Cu lead-free solder, Mater. Sci. Eng. A 618 (2014) 389–397. [34] A. Fawzy, S.A. Fayek, M. Sobhy, E. Nassr, M.M. Mousa, G. Saad, Effect of ZnO nanoparticles addition on thermal, microstructure and tensile properties of Sn–3.5 Ag–0.5 Cu (SAC355) solder alloy, J. Mater. Sci.: Mater. Electron. 24 (2013) 3210–3218. [35] A. Fawzy, S.A. Fayek, M. Sobhy, E. Nassr, M.M. Mousa, G. Saad, Tensile creep characteristics of Sn–3.5Ag–0.5Cu (SAC355) solder reinforced with nano-metric ZnO particles, Mater. Sci. Eng. A 603 (2014) 1–10. [36] Rodney J. McCabe, M.E. Fine, Creep of tin, Sb-solution-strengthened tin, and SbSn-precipitate-strengthened, Metall. Mater. Trans. A A33 (5) (2002) 1531–1539. [37] Rodney J. McCabe, M.E. Fine, High creep resistance tin-based alloys for soldering applications, J. Electron. Mater. 31 (11) (2002) 1276–1282. [38] M. Aghaie-Khafri, Formability of AA8011 aluminum alloy sheet in homogenized and unhomogenized conditions, J. Mater. Sci. 39 (2004) 6467–6472. [39] F.J. Humphreys, M. Hatherly, Recrystallization and Related Annealing Phenomena, 2nd Edition, Elsevier Ltd., Oxford, UK (2004), p. 114, ISBN: 0 08 044164 5. [40] F.A. Mirza, D.L. Chen, A unified model for the prediction of yield strength in particulate-reinforced metal matrix nanocomposites, Materials 8 (2015) 5138–5153. [41] Q.B. Nguyen, M. Gupta, Enhancing compressive response of AZ31B magnesium
114
E.A. Eid et al. / Materials Science & Engineering A 657 (2016) 104–114
alloy using alumina nano-particulates, Compos. Sci. Technol. 68 (2008) 2185–2192. [42] H. Asgharzadeh, A. Simchi, H.S. Kim, Hot deformation of ultrafine-grained Al6063/Al2O3 nanocomposites, J. Mater. Sci. 46 (2011) 4994–5001. [43] X.L. Zhong, W.L.E. Wong, M. Gupta, Enhancing strength and ductility of magnesium by integrating it with aluminum nanoparticles, Acta Mater. 55 (2007) 6338–6344.
[44] K. Mohan Kumar, V. Kripesh, Andrew A.O. Tay, Influence of single-wall carbon nano tube addition on the microstructural and tensile properties of Sn–Pb solder alloy, J. Alloy. Compd. 455 (2008) 148–158. [45] Khin Sandar Tun, M. Gupta, Improving mechanical properties of magnesium using nano-yttria reinforcement and microwave assisted powder metallurgy method, Compos. Sci. Technol. 67 (2007) 2657–2664.