Application of Polymer-Based Composites

9 Application of Polymer-Based Composites: Conductive Pastes Based on Polymeric Composite/ Nanocomposite Ayesha Kausar School of Natural Sciences, National University of Sciences and Technology (NUST), Islamabad, Pakistan

9.1 Introduction Paste or adhesive is a substance applied on surface or in materials to binds them together. Polymer-based conductive pastes have gained recent research interest owing to broad range of technical applications [1]. Properties of conductive adhesives, nature, and material opted for adhesion affect the final material performance [2]. Electrically conductive paste or adhesives may withstand high thermal and physical properties. Various thermosets as well as thermoplastic polymers as well as range of conducting and nonconducting additives have been employed to develop high-tech paste materials. The conductive particle may form strong interlock within the substrate material [3]. Furthermore, polymer wetting, calescence behavior of filler, development of conduction path, and joint microstructure affect the conductive paste properties. The limitations may include low conductivity, joint strength, contact resistance, particle migration, etc. due to meager dispersion of nanoparticle in polymer matrix [4,5]. Electrically conductive adhesives present an alternative to toxic materials used in packaging, microelectronic, and myriad of electronic equipments such as camcorders, hard-drive suspensions, computers, watch electronics, etc. [6]. Electrical conductive adhesive based on nanocomposite of polymers and nanofillers such as metal nanoparticle and nanocarbon owns range of existing properties for high performance applications. The characteristic features of electrical conductive nanocomposite adhesive have been found superior relative to electrical conductive composite adhesives [7]. Main advantages of these conductive adhesives include low-temperature processing conditions, Electrical Conductivity in Polymer-Based Composites: Experiments, Modelling, and Applications. DOI: https://doi.org/10.1016/B978-0-12-812541-0.00009-4 © 2019 Elsevier Inc. All rights reserved.

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fine thermal stability, and high mechanical strength. This chapter basically focuses conducting polymer composite and nanocomposite for conductive paste applications specifically focusing their essential features, types, and significance.

9.2 Conductive Paste The electrically conducting adhesive or paste materials are generally made up of conducting filler powder coated with thermoplastic or thermoset polymer resin. In conductive pastes, filler particles fused with polymer form interaction among filler and contact surface and particles. The surfaces, thus, can be connected through the adhesive material [8,9]. The conducting filler powder consist of Cu, Ag, Au, Pt, Pd, etc. A range of polymeric material used in conductive pastes are epoxy, polyimide, polyester, phenoxy, siloxane, conducting polymers, etc. Uniform dispersion of nanoparticle in resin is essential to form high performance conductive adhesives. Electrically conducting adhesive materials may be some times categorized based on the way of mobility. Isotropic materials are conductive in all directions such as silverparticle filled epoxy. Such materials have found wide applications in the electronics. However, these materials have certain drawbacks including high contact resistance, low electrical conductivity, low joint strength, corrosion issue, etc. Anisotropic materials, on the other hand, have high conductivity and fine interconnections. These materials have relevance in liquid crystal display panels, mounted chips, etc. Viscosity of paste is also an important factor depending on the volume fraction of filler. High conductivity level of paste can be achieved at critical volume fraction of filler material at certain percolation threshold. The electrical conductivity of adhesive materials also depends on temperature conditions [10]. The surfaces can be electrically joined using conducting adhesive (Fig. 9.1). Joining filler particles may develop bonding, during joining process. The conducting particles offer high electrical conductivity and mechanical strength of adhesive surfaces.

9.3 Conducting Polymeric Material Conducting polymer composite and nanocomposite offer unique category of materials with conducting polymer and filler particle or nonconducting polymer with conducting inorganic particles [11]. These materials combine the prevailing properties of parent constituents to

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Figure 9.1 Conducting adhesive material with electrical connection between two surfaces.

Figure 9.2 Processing techniques.

form final composite. However, there are several inherent processing problems of conducting polymers and nanoparticle in matrix. Filler nanoparticles having different size, dimensionality, and properties have been amalgamated with polymers or conducting polymers to form nanocomposite with interesting physical properties and significant potential applications [12]. A large variety of nanoparticles have been reinforced in polymer matrices using various inclusion techniques [13]. Several synthetic strategies such as solution casting, melt processing, in situ techniques, electrospinning techniques, etc. have been used to fabricate various nanostructured materials (Fig. 9.2) [14]. Recently, polymeric nanocomposites have gained interest due to fine physical properties, excellent flexibility, and good processibility compared with the conventional materials [15]. Conducting polymers such as polythiophene (PTh), polyaniline (PANI), polypyrrole (PPy), polyacetylene (PA), poly(para-phenylene) (PPP), polyfuran (PF), etc. have been used [16]. The chemical structures of these polymers are illustrated in Fig. 9.3. Such multifunctional nanocomposites have found application in the fields of energy, sensors, electronics, catalysis, electromagnetic interference shielding, and biomedicine. However, the main challenge for conducting polymers is to increase the electrical

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conductivity. Depending upon the shape, geometries, and dispersion of fillers, nanocomposite may produce low or high percolation thresholds. When the conductive fillers in matrix are far apart, they cannot conduct electricity. The homogeneously dispersed nanoparticle touching each other may tunnel the electrons through the polymer insulator (Fig. 9.4). This tunneling effect is exponential with decreasing distance between the nanofiller [17,18]. The percolation behavior of nonconducting or partially conducting filler depends on the conducting and binding behavior of conducting polymer matrix in nanocomposite (Fig. 9.5). The effect of filler particle or nanoparticle and tunneling distance on the percolation threshold have also been investigated employing various models [19,20]. The morphology of as-synthesized conducting polymer nanocomposites

C H

n Polyphenylene

S

Polythiophene

n

n Poly(p-phenylene vinylene)

N H

NH

C H

O

n

Polypyrrole

n

Polyaniline

n

Polyfuran

Figure 9.3 The chemical structure of conducting polymers.

Figure 9.4 Tunneling effect in conductive polymer nanocomposite with insulating matrix and conducting filler.

Figure 9.5 Conductive nanocomposite with conducting polymer and nonconducting filler.

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also indicate the resulting conductivity properties. Uniform network morphology may enhance interaction between polymer and conducting filler such as carbon nanotube (CNT). Introduction of covalent bonding between polymer and CNT also affect the composite morphology and electrical conductivity. For example, functionalization of multiwalled carbon nanotube (MWCNT) using p-phenylenediamine may result in phenylamine functional groups on nanotube surface. Such nanocomposites may have uniform core sheath structure in which polymer-coated nanotubes form homogeneous network in matrix. Recently, nanostructured conducting polymer composite and nanocomposite have been intensely investigated owing to unique combination of electronic properties of conducting polymers or filler/nanofiller, interfacial interaction, and conducting network of nanomaterials. In particular, such nanomaterials have been exploited in electronic device. Conductivity of electrically conducting polymer and nanocomposite has been enhanced by doping to attain high performance materials. The added high conductivity renders these nanocomposite promising materials for molecular/nanoelectronic devices, electrooptic appliance, microwave absorption, corrosion protection coatings, sensors, actuators, separation membranes, etc.

9.4 Polymeric Materials As Conductive Paste 9.4.1 Polymer/Carbon Composite and Nanocomposite Paste Conductive carbon pastes (CPs) have gained considerable research interest in technological devices and materials [21,22]. The most important application of these pastes has been identified in sensors, biosensors, and related electrodes. The selectivity and the sensitivity of CP electrodes have been enhanced using various chemical modification techniques. In this regard, CP electrode modifications have been found to enhance the electrochemical performance. The polymer/carbon composite pastes resulted in increased selectivity and sensitivity of the determination. Biryol et al. [23] reported CP electrode modified using poly(N-vinylimidazole). The voltammetric behavior of imipramine, HCl and amitriptyline, HCl has been tested with polymer/CP electrode in solutions of different pH. The current density for imipramine was significantly enhance using polymer-modified CP electrode. Ikeda et al. [24] fabricated conductive paste of PANI/carbon black composite. The PANI/carbon black paste was sandwiched between dye-coated TiO2 and

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counter-electrode to construct solid state dye sensitized solar cell. The conversion efficiency up to 4.07% at 100 mW cm2 has been achieved. Dominguez et al. [25] prepared polymer/CP using graphite powder and polyethylenimine. The paste was used to form amperometric biosensor. The biosensor was capable of operating at 1100 mV vs Ag/AgCl and responded linearly to ethanol between 2 μM and 3 mM. Alizadeh et al. [26] introduced molecularly imprinted polymer (MIP) and carbon-based paste to design and construct selective voltammetric sensor for paranitrophenol. The polymer-modified CP-based electrode own high sensitivity compared with neat electrode. The sensor revealed detection limit of 3 3 1029 mol L21. The MIP and CP (MIP-CP) electrode have been employed for para-nitrophenol extraction and determination. Fig. 9.6(I) shows maximum response for the sensor with 0.01 g paste. Higher content of MIP in MIP-CP paste electrode has increased the sensor response owing to greater recognition sites on electrode surface. Though, increasing MIP content more than threshold level has led to a decrease in sensor response. On the other hand, the electrode response with increasing carbon content is given in Fig. 9.6(II). The optimum amount of carbon was 0.05 g to get fine sensor response. Electron transferring capability of electrode was also found to upsurge with increasing carbon content in paste. After a threshold level, the electrode response was decreased via increasing CNT amount. Thus, higher amount of binder in MIP-CP led to low response. This was probably owing to insulating adhesive resulting in low electrode surface conductivity. Gholivand and Torkashvand [27] also reported selective voltammetric sensor for metronidazole via MIP. The metronidazole selective MIP and nonimprinted polymer (NIP) have been prepared and fused with CP electrode. Using various metronidazole concentrations, cathodic stripping voltammetric (CSV) response of MIP-CP and NIP-

Figure 9.6 Optimization of carbon paste electrode compositions; variation of electrode response for para-nitrophenol with changing of (I) MIP and (II) carbon amounts of MIP-CP electrode [26].

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Figure 9.7 The response of sensors based on MIP (black) and NIP (gray) for different metronidazole concentrations. Measurement conditions: 0.1 M BR buffer; pH 5 7.0; tac 5 40s; Eac 5 0.0; stirring rate 5 400 rpm; pulse amplitude 5 50 mV; pulse width 5 40 Ms; and scan rate 60 mV s21 [27].

CP electrodes were tested. Fig. 9.7 shows increase in sensor response of MIP-CP electrode having high metronidazole content. NIP-CP response was found lower compared with the polymer/carbon paste electrode. Thus, MIP-CP electrode revealed high recognition ability relative to NIP-CP electrode due to the incorporation of modified polymer in the system. The detection limit of sensor was obtained as 3.59 3 1025 mg L21. Research have, thus, revealed the success of polymer-modified carbon adhesives in sensor technology. However, further research and studies may lead to interesting results and several other technical applications of polymer/carbon pastes. CNTs have been used as an important polymer/ carbon paste material [28]. CNTs possess high surface area, electrical conductivity, mechanical strength, and chemical stability [29]. The paste electrode of single-wall CNT with mineral oil (without polymer) has also been prepared. The electrochemical behavior and selectivity of CNT adhesives have been found better compared with the carbon, carbon black, or graphite paste electrode. One of the most promising ways to enhance the performance of CNT paste electrode is modification using polymer [30]. The polymer modification may cause facile fabrication and prospect of surface regeneration in materials. Antiochia and Gorton [31] prepared CNT paste electrode modified with an osmium functionalized polymer. The paste was used to develop an amperometric biosensor for

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glucose monitoring. The paste was considered as an arbitrator towards electron mobility among the CNT paste electrode and immobilized diaphorase. The biosensor revealed detection limit of 10 μmol L21, sensitivity of 13.4 A cm22 mmol21 L21, and good reproducibility of 2.1%. Raoof et al. [32] electropolymerized o-toluidine (OT) monomer in the presence of aqueous acidic solution containing nonionic surfactant Triton X-100 (TX-100) on multiwalled CNT paste electrode (CNTPE). The substrate was employed as porous matrix for Ni(II) dispersion. The nickel/poly (o-toluidine)/Triton X-100 film-modified CNT paste electrode (Ni/POT (TX-100)/MCNTPE) showed redox behavior of Ni(III)/Ni(II) couple in alkaline medium. Moreover, POT/TX-100 film at CNTPE surface enhanced catalyst performance for formaldehyde electrooxidation. Field emission scanning electron microscopic (FESEM) image of the POT/ MCNTPE revealed scaly granular structure (Fig. 9.8A). TX-100 improved the uniformity of POT (TX-100)/MCNTPE surface (Fig. 9.8B). Large spherical scaly aggregates can be seen for Ni/POT/ MCNTPE due to settlement of deposits (Fig. 9.8C). Nickel ion dispersed in POT (TX-100)/MCNTPE showed decreased aggregation of nickel (Fig. 9.8D). Polarization behavior was inspected using cyclic voltammetry (CV) technique in 0.1 M NaOH after incorporation of Ni ions in polymer. There was noteworthy difference observed between CV of immobilized Ni

Figure 9.8 Typical FE-SEM images of different modified electrodes: (A) POT/ MCNTPE, (B) POT (TX-100)/MCNTPE, (C) Ni/POT/MCNTPE, and (D) Ni/POT (TX-100)/MCNTPE. [32].

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Figure 9.9 CVs of Ni(OH)2/POT/MCNTPE (A) and Ni(OH)2/POT (TX-100)/ MCNTPE (B) in 0.1 M NaOH solution at y 5 50 mV s21 [32].

(OH)2 on POT/MCNTPE (Fig. 9.9A) and POT (TX-100)/MCNTPE (Fig. 9.9B). There was increase in the area under the curve for Ni/POT (TX100)/MCNTPE showing the effect of ion immobilization. Various type of CNT can be used for electroanalytical applications. Among these, paste are the most popular carbon electrode materials [33,34]. Thus, polymer/CNTpaste electrodes have been efficiently used in electroanalysis owing to low cost, chemical inertness, wide potential window, and high sensing and detection [35,36].

9.5 Polymer/Metal Nanoparticle Nanocomposite Paste 9.5.1

Polymer/Copper Nanocomposite Paste

Among noble metal nanoparticles (gold, silver, copper, etc.), copper nanoparticles have been more attractive due to high conductivity and low cost [37]. However, one of the drawbacks to use copper nanoparticle in conductive pastes is rapid oxidation in ambient air. Capping agents have been used in this regard to shield Cu nanoparticle. Cationic, anionic, or nonionic surfactants and polymers have been

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employed to save copper nanoparticle [38,39]. A conductive paste based on copper powder and epoxy resin has been developed using resol type phenol curing agent [40]. The paste showed fine moisture resistance, adhesion, and high conductivity level [41]. Zhao et al. [42] prepared copper conductive adhesive based on epoxy resin, hardener (m-phenylenediamine and diaminodiphenylm ethane), and copper particles. Fig. 9.10 shows scanning electron microscopy (SEM) micrograph of copper powder before and after modified by silane coupling agents (SCA). In the conductive paste, mass ratio of copper powder to SCA was 100:3 and ratio of epoxy resin to hardener was 100:20. The specimens were heated at different temperature. The copper powder modified by SCA revealed fine dispersion. Fig. 9.11 shows the adhesion strength of samples cured at different temperature. The adhesion strength enhanced on heating and attained value 20.05 MPa at 145 C. Fig. 9.12 shows decrease in bulk resistivity of conductive adhesive with the increase in

Adhesive strength (MPa)

Figure 9.10 SEM micrograph of copper powder (A) raw copper powder and (B) modified copper powder [42].

20 16 12 8 4 0 80

100

120

140

160

180

Curing temperature (°C) Figure 9.11 Influence of curing temperature on adhesive strength [42].

Bulk resistivity (10–3Ω cm)

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6 5 4 3 2 1 0 40

50 60 70 Copper powder content (%)

80

Figure 9.12 Influence of copper powder on bulk resistivity (mass ratio of epoxy resin to hardener is 100:20) [42].

copper powder content. The bulk resistivity of conductive adhesive was 1.52 3 1023 Ω cm with 65 wt.% copper powder content. The percolation threshold in nanocomposite paste was explained on the basis of three phases of bulk resistivity change with increase in copper content. Initially, copper powder in conductive adhesive formed interconnected conductive channels at high bulk resistivity. High Cu content connected the conducting framework. At certain critical content of copper powder, adhesive conductive channels formed 3D channels conductive loop. At this point, the bulk resistivity was decreased sharply. Pham et al. [43] prepared conductive paste of copper nanoparticle mixed with poly(3,4ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS). Cetyl trimethylammonium bromide (CTAB) and polyvinylpyrrolydone (PVP) were used as stabilizers. Influence of copper content on the electrical conductivity and stability of nanocomposite was investigated. The conductive paste with varying content is given in Table 9.1. Fig. 9.13 shows specific conductivity of pastes versus dodecylbenzenesulfonate (SDBS) content. When the surfactant concentration was varied from 1 to 5 wt.%, the conductivity of copper paste was decreased. Surfactant was found to behave as a barrier of charge transport. The conductivity of paste was decreased due to increased interdistance and decreased contact area among nanoparticles in conducting network [44,45]. Thus, decrease in surfactant content revealed high conductivity [46].

9.5.2

Polymer/Silver Nanocomposite Paste

High performance conductive adhesives have been designed using thermosetting resin and electrically conductive filler. Silver has been

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Table 9.1 Conductivity of Pastes With Different Compositions [43] PEDOT/PSS (wt.%) Cu (wt.%) SDBS (wt.%) Conductivity (S cm21) 0 0.5 0.5 0.5 1 1 1 1.5 1.5 1.5

Conductivity (S cm–2)

0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5

9.64 3 1024 2.74 3 1023 4.63 3 1024 3.41 3 1025 7.23 3 1023 8.27 3 1024 5.93 3 1025 2.94 3 1024 1.38 3 1025 4.36 3 1027

0 1 2 5 1 2 3 1 2 5

0.0085 0.0080 0.0075 0.0070 0.0065 0.0060 0.0055 0.0050 0.0045 0.0040 0.0035 0.0030 0.0025 0.0020 0.0015 0.0010 0.0005 0.0000

Cu:PEDOT/PSS 1:1 wt.% Cu:PEDOT/PSS 2:1 wt.% Cu:PEDOT/PSS 3:1 wt.%

0

1

2

3

4

5

SDBS wt.%

Figure 9.13 Relationship between specific conductivity of paste and SDBS weight percent with different weight ratio Cu powder/polymer. [43].

employed as prevalent electrically conductive filler owing to high conductivity. Electrically conductive adhesives of epoxy/silver have been successfully employed in electronic devices due to various excellent properties such as high flexibility, low curing temperature, thin-lead solders, etc. [47]. Lu et al. [48] fabricated conductive adhesives of polymer/silver flake composite. Thermal stability of conductive adhesives was studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Interaction between polymer and silver

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Resistivity (Ω cm)

0.01

1E–3

1E–4

1E–5 100

120

140 160 Temperature (°C)

180

200

Figure 9.14 Effect of treatment temperature (for 30 min) on film resistivity film made of pure nano-sized colloids silver content 5 84.8 vol.%) [51].

flake was studied by diffuse reflectance infrared spectroscopy (DRIR). Jiang et al. [49] investigated electrical properties of nanosilver filled conductive adhesives. Low resistivity of silver nanoparticle-based adhesive was found as 2 3 1024 Ω cm. Jiang et al. [50] incorporated diacid functionalized silver nanoparticle in polymer matrix to form conductive adhesive. The resistivity of functional silver nanoparticle incorporated polymer nanocomposite paste was affectedly reduced to 5 3 1026 Ω cm. Lee et al. [51] developed nano-sized silver colloids and poly(vinyl acetate) (PVAc) paste. Inclusion of Ag nanoparticle up to percolation threshold level decreased the resistivity due to formation of conductive paths in the materials. Nano-sized silver colloids with volume fraction of 0.848 had low resistivity of 1.93 3 1024 Ω cm. Here, the addition of high micro-sized silver flake content increased the resistivity due to increased contact resistance. Upsurge temperature assisted to fabricate contacts between the silver colloids and increased the conductivity (Fig. 9.14). Resistivity can be significantly reduced through heating. Tongxiang et al. [52] developed epoxy and silver powder-based paste with 25 wt.% Ag. The epoxy resin/Ag conductive adhesive has shown percolation concentration of 28 vol.%. The conductive adhesives based on epoxy and Ag powder revealed low cost, high tensile strength, and failure elongation compared with pure silver conductive adhesive. The resistivity of conductive adhesives filled with silver content is given in Table 9.2. The conductive adhesive revealed electrical conductivity up to 1.2 3 1023 Ω cm. The dependence of electrical resistivity of conductive adhesives is shown in Fig. 9.15. Neat silver filler revealed percolation concentration of 13 vol.% (40 wt.%) and the resistivity was 20 vol.

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Table 9.2 Characters of Conductive Adhesives [52]

Filler Graphite powder 30 vol.% Ag plating graphite powder 30 vol.% Ag powder 25 vol.%

Specific Surface (m2/g)

Electrical Adhesion Resistivity Strength (MPa) 1023 Ω cm

4.0

7.3

62

3.8

7.6

1.2

1.2

7.5

0.9

4 3 Ag Graphite Ag plating graphite

2

log (p)

1 0 –1 –2 –3 –4 0

10

20 30 40 Filler content (vol%)

50

60

Figure 9.15 Log resistivity of conductive adhesives as a function of filler content [52].

% (55 wt.%). For Ag filled adhesive, percolation concentration was 28 vol.% (about 20 wt.%). In Ag plating, the percolation concentration of conductive adhesive is high, i.e., .20 wt.%. Polymer and silver particle-based conductive adhesive possess benefit of cost-effectiveness. Moreover, these adhesives exhibit high tensile strength and failure elongation compared with the pure Ag conductive adhesive.

9.5.3 Polymer/Zinc Nanocomposite Paste In batteries and fuel cells, porous electrodes have gained interest owing to efficient and high surface area. Zinc powder and polymers

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have been used to form conductive paste for porous electrodes [53]. Several methods have been used prepare porous zinc materials [54]. These electrodes can be electrodeposited from an aqueous electrolytic bath [55]. Roll-bonded process has also been used with a mixture of zinc and polymer [56]. Solvent extrusion method to form thin sheet is also successful. Another method is compressed dry powder process, in which powder mixture of zinc and binder is placed in a mold and compressed. Another way is to prepare paste or slurry of powdered zinc oxide in solution to form a paste. The paste or slurry then can be applied on metal grid and dried to form an electrode [57]. Porous zinc electrode was prepared using zinc powder mixture and thick gelatinous biodegradable polysaccharide solution as binder. The zinc air cell was prepared having specific energy density of 1470 mAh [58]. Othman et al. [59] also prepared porous zinc anode using mixture of zinc and biodegradable polysaccharide solution as binding agent. The polymer solution concentration was speckled to find best electrode composition. The polymer layer was familiarized between electrode-gelled electrolyte interface ensuing improved cell discharge performances. Zinc air cell galvanostatic discharge capability was used to study the electrode performance. The zinc electrode validated the capacity of 2066 mAh and specific energy density of 443 Wh kg21. The use of conductive polymer/zinc paste in electrodes has been used to considerably enhance the cell discharge capabilities.

9.6 Significance and Summary Several conducting composite and nanocomposite formulations have been developed to overcome the limitations of conventional paste materials. Thermoplastic as well as thermoset resins have been incorporated with metal nanoparticle and nanocarbon and carbon fillers to meet the requirements of high performance applications [60]. The polymeric composite and nanocomposite paste materials have been successfully developed by melt mixing the powder particles, solution casting the thermoplastic polymer resin and filler particles, and using other techniques. Polymers are low cost coating materials in these formulations. The polymeric materials provide bonding among filler and substrate, so increasing the electrical and mechanical properties of the materials. Loading metal nanoparticle in epoxy or thermoplastics has render high electrical conductivity of conducting pastes [10,61]. On the other hand, conducting polymers and carbon particles have also been used as matrix

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for conductive paste materials. Both types of conductive paste (insulating polymer 1 conducting particle or conducting polymer 1 filler) have shown promising results of electrical conductivity, impact strength, and reliability compared with the conventional conductive adhesives. The electrical characteristics of CNT, graphene, modified graphene, and other carbon nanofiller suggest their electron passing capability in nanocomposite systems. The use of nanomaterial-based pastes possesses inherent physical and chemical properties to for hightech uses. The conductive pastes with silver, copper, zinc, and other metal particles may form partially coalesced connection strengthened by polymer. Consequently, the highly conductive composite adhesive has constructed to see the benefits of the polymer and the nanofiller [62]. To improve the paste performance, modified particles have also been prepared. The modified conducting fillers, thus, may provide interfacial interaction among filler and the polymer, and adhesive bonding between the conductive paste and the surface [63]. Addition of poly(N-vinylimidazole) or other conducting additive may enhance the conductivity of the polymer-based electrode. Additive has been found to enhance the current densities and electrical conductivity with the increasing content. At significantly high additive content, no significant electroactivity was observed. Another important aspect of these conductive composite or nanocomposite paste is the filler dispersion in polymer. Homogeneous and uniform dispersion of nanofiller or filler particles may develop fine intersects between them, thus increasing the overall conductivity of the adhesive material. The dispersion properties depend upon the processing technique used, filler type, modification, as well as interfacial interaction between matrix and filler. The conducting polymer and carbon composite paste electrodes have been recognized for superior electrode performance and steadiness. The paste materials further modified using suitable materials may facilitate the selectivity and the sensitivity of determinations. Advance conducting polymer/CNT, polymer/graphene, polymer/carbon black, etc. have been used to develop fascinating paste systems for technological applications. Conclusively, this chapter is intended to present brief appraisal of the paste techniques. Hence, fundamentals, features, and various types of conductive composite and nanocomposite paste have been deliberated. The developments in polymeric composite and nanocomposite pastes point to future applications in high-tech microelectronic industry.

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