- Email: [email protected]
Temperature distributions in hybrid circuit substrates
WORLD
ABSTRACTS ON MICROELECTRONICS AND RELIABILITY
was chosen for the resistor element, and evaluation into the maximum rating of film area was undertaken in terms of both load stability and overload--the latter being considered in parallel with substrate thickness. Utilizing a substrate of 0.6 x 0"5 x 0.1 in., it was found that all the laid down parameters could be met when the resistor film was rated at 45 W per square inch of area.
Temperature distributions in hybrid circuit substrates. R. E. JAMISON and G. H. RE~. Proceedings ISHAI Microelectronics Symposium, October-November (1972), p. 5-A-3-1. Alumina and beryUia hybrid circuit substrates have been studied analytically to predict transient and steady-state temperature distributions in the vicinity of power dissipating components. An adaptable model divided the substrate into 200 nodes. Two dissipators are on adjacent comers of the top surface, and the bottom surface is in contact with a constant temperature heat sink. Heat flow equations are solved for each of five combinations of material, power inputs, power input areas, and the heat transfer coefficient at the heat sink. Temperature maps of the top surface are presented along with temperature vs. time plots for heat sources and selected top surface nodes. Also, maximum top-surface temperature differences (differences between the heat source temperatures and the lowest top surface temperature) are plotted vs. time, and selected steady state temperatures are listed. The results can be used to predict, in a variety of circuits, the effects of a power dissipating device on nearby temperature sensitive devices. In contrast to the comparison of actual heat source temperatures, the maximum top surface temperature differences and the differences in the heat source temperatures for different material conductivities show an improvement by a factor nearly equal to the ratio of conductivities (,~6 : 1).
Thermal expansion compatibility of c e r a m i c chip capacitors m o u n t e d on a l u m i n a substrates. R. V.
213
ture and moisture on the bulk resistivity of the oxides in powder, sintered and crystalline form were determined and static and dynamic volt-ampere characteristics were obtained. Sintered samples tested showed better electrical stability than the compressed powder samples. Two types of commercially available vandium pentoxide were heat treated to obtain various crystalline oxide forms which were mounted on alumina substrates and terminated by thick-film conductors for making electrical connections. Indications are that these materials could have applications as sensors, critical temperature resistors, high-speed switches and temperature compensation elements in hybrid microelectronic circuits.
Hybrid tantalum chip capacitors. A n e w encapsulated tantalum chip capacitor designed especially for direct microcircuit substrate mounting. S. A. BELL and W. J. HYLAND. Proceedings I S H M Microelectronics Symposium, October-November (1972), p. 4A-l-1. This paper presents an insight into chip tantalum capacitor development with design considerations used in producing an advanced hybrid tantalum chip capacitor. Construction details utilizing unique solid tantalum capacitor processing techniques in concert with hybrid design requirements, are explored. Mounting, bonding and handling methods are discussed. Data are presented comparing the hybrid tantalum with currently available products with their relative advantages and disadvantages. Included are volumetric and surface area efficiencies, life test, and mounting time temperature results. Eight case sizes are available with ratings from 0.1 to 100 vtf, with the smallest size 0-050 x 0-050 x 0.100 in. with a maximum capacity of 2.2 ttf.
Investigation of mounting discrete chip components for hybrid microelectronic applications. S. V. CARUSO, R. V. ALLEN and R. T. HOWARD. Proceedings I S H M Microelectronics Symposium, October-
Experimental studies and applications of v a n a d i u m oxides. L. WILLIAMS,Jr. Proceedings I S H M Microelectronics Symposium, October-November (1972), p. 4-
November (1972), p. 3-A-l-1. In the assembly of hybrid microcircuits, passive and active discrete chip components are attached by epoxy cements and by solders. This study was initiated to determine the integrity of such attachments. Alumina substrates were subjected to a group of thermal and mechanical test environments defined by test methods in M I L - S T D 883. Lot samples of substrates with assembly variations were subjected to separately applied testing and to serial testing. These test methods were applied sequentially to the same lot of substrates. Epoxy cements were generally satisfactory with respect to separate tests, although sequential tests severely degraded epoxy bond strengths of all types. Bond strengths to unglazed substrates were slightly superior to those of the same components on glazed types. Solder joints were vulnerable to catastrophic failure in several environments, especially temperture cycling and thermal shock. Vibration and impact shock also produced solder joint failures.
A-5-I. Electrical and electro-chemical properties of commercial grades of CuO, Cu20, and VtO 6 were investigated. However, in this paper only oxides of vanadium are considered. Effects of pressure, tempera-
Computer controlled test s y s t e m s - - c a n hybrid circuit manufacturers e m p l o y t h e m successfully? B. A. SHAH. Proceedings I S H M Microelectronics Sympo-
ALLEN, S. V. CARUSO,L. K. WILSON and D. L. KINSER. Proceedings I S H M Microelectronics Symposium, OctoberNovember (1972), p. 5-A-5-1. The thermal expansion coefficients of a representative sample of BaTiOa and TiO2 ceramic chip capacitors and alumina substrates have been examined. These data have revealed large potential mechanical stresses under thermal cycling. A mathematical analysis of a composite model of the capacitor to predict the thermal expansion and modulus of elasticity and an analysis of the capacitor-substrate system to predict the magnitude of thermally induced stresses have been conducted. In all cases studied, thermally induced stresses great enough to cause capacitor body rupture or termination failure was predicted.
ABSTRACTS ON MICROELECTRONICS AND RELIABILITY
was chosen for the resistor element, and evaluation into the maximum rating of film area was undertaken in terms of both load stability and overload--the latter being considered in parallel with substrate thickness. Utilizing a substrate of 0.6 x 0"5 x 0.1 in., it was found that all the laid down parameters could be met when the resistor film was rated at 45 W per square inch of area.
Temperature distributions in hybrid circuit substrates. R. E. JAMISON and G. H. RE~. Proceedings ISHAI Microelectronics Symposium, October-November (1972), p. 5-A-3-1. Alumina and beryUia hybrid circuit substrates have been studied analytically to predict transient and steady-state temperature distributions in the vicinity of power dissipating components. An adaptable model divided the substrate into 200 nodes. Two dissipators are on adjacent comers of the top surface, and the bottom surface is in contact with a constant temperature heat sink. Heat flow equations are solved for each of five combinations of material, power inputs, power input areas, and the heat transfer coefficient at the heat sink. Temperature maps of the top surface are presented along with temperature vs. time plots for heat sources and selected top surface nodes. Also, maximum top-surface temperature differences (differences between the heat source temperatures and the lowest top surface temperature) are plotted vs. time, and selected steady state temperatures are listed. The results can be used to predict, in a variety of circuits, the effects of a power dissipating device on nearby temperature sensitive devices. In contrast to the comparison of actual heat source temperatures, the maximum top surface temperature differences and the differences in the heat source temperatures for different material conductivities show an improvement by a factor nearly equal to the ratio of conductivities (,~6 : 1).
Thermal expansion compatibility of c e r a m i c chip capacitors m o u n t e d on a l u m i n a substrates. R. V.
213
ture and moisture on the bulk resistivity of the oxides in powder, sintered and crystalline form were determined and static and dynamic volt-ampere characteristics were obtained. Sintered samples tested showed better electrical stability than the compressed powder samples. Two types of commercially available vandium pentoxide were heat treated to obtain various crystalline oxide forms which were mounted on alumina substrates and terminated by thick-film conductors for making electrical connections. Indications are that these materials could have applications as sensors, critical temperature resistors, high-speed switches and temperature compensation elements in hybrid microelectronic circuits.
Hybrid tantalum chip capacitors. A n e w encapsulated tantalum chip capacitor designed especially for direct microcircuit substrate mounting. S. A. BELL and W. J. HYLAND. Proceedings I S H M Microelectronics Symposium, October-November (1972), p. 4A-l-1. This paper presents an insight into chip tantalum capacitor development with design considerations used in producing an advanced hybrid tantalum chip capacitor. Construction details utilizing unique solid tantalum capacitor processing techniques in concert with hybrid design requirements, are explored. Mounting, bonding and handling methods are discussed. Data are presented comparing the hybrid tantalum with currently available products with their relative advantages and disadvantages. Included are volumetric and surface area efficiencies, life test, and mounting time temperature results. Eight case sizes are available with ratings from 0.1 to 100 vtf, with the smallest size 0-050 x 0-050 x 0.100 in. with a maximum capacity of 2.2 ttf.
Investigation of mounting discrete chip components for hybrid microelectronic applications. S. V. CARUSO, R. V. ALLEN and R. T. HOWARD. Proceedings I S H M Microelectronics Symposium, October-
Experimental studies and applications of v a n a d i u m oxides. L. WILLIAMS,Jr. Proceedings I S H M Microelectronics Symposium, October-November (1972), p. 4-
November (1972), p. 3-A-l-1. In the assembly of hybrid microcircuits, passive and active discrete chip components are attached by epoxy cements and by solders. This study was initiated to determine the integrity of such attachments. Alumina substrates were subjected to a group of thermal and mechanical test environments defined by test methods in M I L - S T D 883. Lot samples of substrates with assembly variations were subjected to separately applied testing and to serial testing. These test methods were applied sequentially to the same lot of substrates. Epoxy cements were generally satisfactory with respect to separate tests, although sequential tests severely degraded epoxy bond strengths of all types. Bond strengths to unglazed substrates were slightly superior to those of the same components on glazed types. Solder joints were vulnerable to catastrophic failure in several environments, especially temperture cycling and thermal shock. Vibration and impact shock also produced solder joint failures.
A-5-I. Electrical and electro-chemical properties of commercial grades of CuO, Cu20, and VtO 6 were investigated. However, in this paper only oxides of vanadium are considered. Effects of pressure, tempera-
Computer controlled test s y s t e m s - - c a n hybrid circuit manufacturers e m p l o y t h e m successfully? B. A. SHAH. Proceedings I S H M Microelectronics Sympo-
ALLEN, S. V. CARUSO,L. K. WILSON and D. L. KINSER. Proceedings I S H M Microelectronics Symposium, OctoberNovember (1972), p. 5-A-5-1. The thermal expansion coefficients of a representative sample of BaTiOa and TiO2 ceramic chip capacitors and alumina substrates have been examined. These data have revealed large potential mechanical stresses under thermal cycling. A mathematical analysis of a composite model of the capacitor to predict the thermal expansion and modulus of elasticity and an analysis of the capacitor-substrate system to predict the magnitude of thermally induced stresses have been conducted. In all cases studied, thermally induced stresses great enough to cause capacitor body rupture or termination failure was predicted.