- Email: [email protected]
Stress screening can benefit a pipeline requirement
1028
World Abstracts on Mircoelectronics and Reliability
behavior. The effect of density of mounting on thermal resistance of the packages is measured by IR imaging experiments. Package pitch, relative orientation of neighboring packages, and one-sided versus double-sided mountings are parameters that were varied in these experiments.
Surge current failure in solid electrolyte tantalum capacitors. BORIS M. MOGILEVSKYand GEORGE A. SHIRN. IEEE Trans. Compon. Hybrids mf9 Technol. CHMT-9 (4), 475 (1986). Fast charging and discharging of solid tantalum capacitors causes breakdown by heating in the MnO2 cathode instead of dielectric breakdown. It appears that localized regions of lower resistance and poor thermal contact to a heat sink allow very high temperatures to occur. These "hot spots" can then cause breakdown of the adjacent dielectric film and, eventually, loss of the capacitor. Temperature increases are detected by measuring the change of resistance of the MnO z cathode and by their effect on temperature sensitive paint. The hot spots tend to concentrate near the surface of the anode at the upper and lower shoulders. The heating effect of leakage current is negligible for these tests. Fatigue of 60/40 solder. HARVEY D. SOLOMON. IEEE Trans. Compon. Hybrids mf,q Technol. CHMT-9 (4), 423 (1986). Plastic strain versus fatigue life data are presented for tests run at - 5 0 , 35, 125, and 150°C. It was found that these data could be correlated by the Coffin-Manson fatigue law, with an exponent of approximately 0.5 for the tests run at - 3 5 ° C to 125°C. At 150°C the exponent was reduced to 0.37. These results were obtained for plastic strain limited tests. Different results are obtained when total strain limits are employed. This difference is discussed. The influence of cycling frequency and temperature changes are also discussed. A model is presented which describes the influence of plastic strain and cycling frequency. Corrections to the model predicted fatigue life, which account for temperature changes, cycling waveshape, and joint geometries, are also discussed. Comparison of the stability of gold and palladium alloy connector contacts subjected to vibration. EDWARD S. SI'ROLES and MICHAEL H. DROZDOW1CZ, IEEE Trans. Compon. Hybrids mfg Technol. CHMT-9 (4), 480 (1986). Printed wiring board connector contacts utilizing gold and various palladium based alloys have been subjected to vibration testing to accelerate degradation caused by fretting or
3. C I R C U I T
AND
SYSTEMS
RELIABILITY,
Bounds on reliability of a coherent system with positively correlated components. C. D. LAI. IEEE Trans. Reliab. R-35 (5), 508 (1986). An upper bound on the reliability of a coherent system of positively correlated components is obtained via an improved Bonferroni inequality. An example is given. The bound is sharper if the joint survival probability is known for each pair of components. Stress screening can benefit a pipeline requirement. CmrNG L. WONG and ROBERT L. ZIMMERMAN. Proc. a. Reliab. Maintainab. Syrup., 125 (1987). As environmental stress screening becomes more elaborate for military equipment, the traditional factory benefits from stress screening are no longer enough to convince the customer to reach into his somewhat less than deep pocket to pay for it. An often overlooked and underemphasized benefit from stress screening is that of reduced field problems. If the stress screening can be shown to be effective, then the pipeline benefits resulting from fewer field problems can be huge and the corresponding dollars savings will be significant. The magnitude of these savings, if convincingly derived and presented, can be a tremendous help in deciding whether an extensive stress screen program is a go or not. An example of this
frictional polymer formation. The resistance of each contact was measured before the test and at various intervals throughout the test. The results show that the contacts with the maximum gold content are the most stable in this test. Pure palladium contacts mated with pure palladium contacts are the least stable. Further tests have shown thal palladium-based materials covered with thin gold or goldrich layers perform satisfactorily.
Reliability of metallized ceramic/polyimide substrates. THOMAS R. HOMA and ANTHONY J. POSOCCO. IEEE Trans. Compon. Hybrids mJ~l TechnoL CHMT-9 (4), 396 (1986). A new packaging technology has been developed to allow increased switching speeds, lower noise levels, and increased circuit density. The package consists of a ceramic substrate with two layers of copper circuitry separated by a polyimide layer. Extensive accelerated stress testing was performed on the chip carrier to determine the reliability exposures. We found no dielectric or interlayer failures after 2000h at 85°C/80 percent relative humidity (RH). Almost no detectable resistance drift was observed in the interlayer connections. It was concluded that the polyimide chip carrier is very stable and will meet or exceed all design objectives. The preparation and properties of 4.7 ttF 2220 size 50 V Z5U relaxor multilayer ceramic capacitors. JOHN H. ALEXANDER, DAWN A, JACKSONand ERIC L. BUSH. IEEE Trans. Compon. ftybrids mfq Technol. CHMT-9 (4), 464 (1986). A new dielectric for multilayer ceramic capacitors is currently undergoing factory qualification. This dielectric is based on a nonstoichiometric lead magnesium niobate relaxor material. Dielectric constants in excess of 15,000 have been achieved for bodies which sinter close to 900°C with 100 percent Ag internal electrodes. The use of very high Ag content electrode systems means that there is a considerable cost reduction so that multilayer ceramic chip capacitors become cost competitive with solid tantalum chip capacitors. The preparation and properties of the dielectric material are described and life test data are presented showing that capacitors of the new dielectric are extremely stable for periods up to two years at ambient and upper rated temperature. A direct comparison is made between the electrical properties of 4.7 ~tF 50 V 2220 size Z5U multilayer chip capacitors manufactured from the new relaxor dielectric and the equivalent value tantalum chip capacitors.
MAINTENANCE
AND
REDUNDANCY
winning process on a tactical missile is presented here as a case study.
A datebase design for automated RAM analysis. BOB WALSH. Proc. a. Reliab. Maintainab. Syrup., 104 (1987). The widespread acceptance of computational methods fur design evaluation has helped bring product assurance into the design process. This progress is threatened by CAD/CAE tools that accelerate the design phase but do not interact with RAM software. We have designed a relational data structure that stores output from most schematic capture and CAE programs. Input for most RAM software and management information systems can be extracted directly from this structure. The complete design contains over 50 tables. Subsets of the full design have been used for three different prototypes that are already finding practical application. Quality and reliability data collection and analysis system in integrated manufacturing of computer hard-ware. H. NAKAMURA, T. HAKUCHOH and T. KAWAKAMI. Proc. 16th Syrup. Reliab. Maintainab. Japan, 42 (1986). The quality and reliability data in vertically integrated manufacturing
World Abstracts on Mircoelectronics and Reliability
behavior. The effect of density of mounting on thermal resistance of the packages is measured by IR imaging experiments. Package pitch, relative orientation of neighboring packages, and one-sided versus double-sided mountings are parameters that were varied in these experiments.
Surge current failure in solid electrolyte tantalum capacitors. BORIS M. MOGILEVSKYand GEORGE A. SHIRN. IEEE Trans. Compon. Hybrids mf9 Technol. CHMT-9 (4), 475 (1986). Fast charging and discharging of solid tantalum capacitors causes breakdown by heating in the MnO2 cathode instead of dielectric breakdown. It appears that localized regions of lower resistance and poor thermal contact to a heat sink allow very high temperatures to occur. These "hot spots" can then cause breakdown of the adjacent dielectric film and, eventually, loss of the capacitor. Temperature increases are detected by measuring the change of resistance of the MnO z cathode and by their effect on temperature sensitive paint. The hot spots tend to concentrate near the surface of the anode at the upper and lower shoulders. The heating effect of leakage current is negligible for these tests. Fatigue of 60/40 solder. HARVEY D. SOLOMON. IEEE Trans. Compon. Hybrids mf,q Technol. CHMT-9 (4), 423 (1986). Plastic strain versus fatigue life data are presented for tests run at - 5 0 , 35, 125, and 150°C. It was found that these data could be correlated by the Coffin-Manson fatigue law, with an exponent of approximately 0.5 for the tests run at - 3 5 ° C to 125°C. At 150°C the exponent was reduced to 0.37. These results were obtained for plastic strain limited tests. Different results are obtained when total strain limits are employed. This difference is discussed. The influence of cycling frequency and temperature changes are also discussed. A model is presented which describes the influence of plastic strain and cycling frequency. Corrections to the model predicted fatigue life, which account for temperature changes, cycling waveshape, and joint geometries, are also discussed. Comparison of the stability of gold and palladium alloy connector contacts subjected to vibration. EDWARD S. SI'ROLES and MICHAEL H. DROZDOW1CZ, IEEE Trans. Compon. Hybrids mfg Technol. CHMT-9 (4), 480 (1986). Printed wiring board connector contacts utilizing gold and various palladium based alloys have been subjected to vibration testing to accelerate degradation caused by fretting or
3. C I R C U I T
AND
SYSTEMS
RELIABILITY,
Bounds on reliability of a coherent system with positively correlated components. C. D. LAI. IEEE Trans. Reliab. R-35 (5), 508 (1986). An upper bound on the reliability of a coherent system of positively correlated components is obtained via an improved Bonferroni inequality. An example is given. The bound is sharper if the joint survival probability is known for each pair of components. Stress screening can benefit a pipeline requirement. CmrNG L. WONG and ROBERT L. ZIMMERMAN. Proc. a. Reliab. Maintainab. Syrup., 125 (1987). As environmental stress screening becomes more elaborate for military equipment, the traditional factory benefits from stress screening are no longer enough to convince the customer to reach into his somewhat less than deep pocket to pay for it. An often overlooked and underemphasized benefit from stress screening is that of reduced field problems. If the stress screening can be shown to be effective, then the pipeline benefits resulting from fewer field problems can be huge and the corresponding dollars savings will be significant. The magnitude of these savings, if convincingly derived and presented, can be a tremendous help in deciding whether an extensive stress screen program is a go or not. An example of this
frictional polymer formation. The resistance of each contact was measured before the test and at various intervals throughout the test. The results show that the contacts with the maximum gold content are the most stable in this test. Pure palladium contacts mated with pure palladium contacts are the least stable. Further tests have shown thal palladium-based materials covered with thin gold or goldrich layers perform satisfactorily.
Reliability of metallized ceramic/polyimide substrates. THOMAS R. HOMA and ANTHONY J. POSOCCO. IEEE Trans. Compon. Hybrids mJ~l TechnoL CHMT-9 (4), 396 (1986). A new packaging technology has been developed to allow increased switching speeds, lower noise levels, and increased circuit density. The package consists of a ceramic substrate with two layers of copper circuitry separated by a polyimide layer. Extensive accelerated stress testing was performed on the chip carrier to determine the reliability exposures. We found no dielectric or interlayer failures after 2000h at 85°C/80 percent relative humidity (RH). Almost no detectable resistance drift was observed in the interlayer connections. It was concluded that the polyimide chip carrier is very stable and will meet or exceed all design objectives. The preparation and properties of 4.7 ttF 2220 size 50 V Z5U relaxor multilayer ceramic capacitors. JOHN H. ALEXANDER, DAWN A, JACKSONand ERIC L. BUSH. IEEE Trans. Compon. ftybrids mfq Technol. CHMT-9 (4), 464 (1986). A new dielectric for multilayer ceramic capacitors is currently undergoing factory qualification. This dielectric is based on a nonstoichiometric lead magnesium niobate relaxor material. Dielectric constants in excess of 15,000 have been achieved for bodies which sinter close to 900°C with 100 percent Ag internal electrodes. The use of very high Ag content electrode systems means that there is a considerable cost reduction so that multilayer ceramic chip capacitors become cost competitive with solid tantalum chip capacitors. The preparation and properties of the dielectric material are described and life test data are presented showing that capacitors of the new dielectric are extremely stable for periods up to two years at ambient and upper rated temperature. A direct comparison is made between the electrical properties of 4.7 ~tF 50 V 2220 size Z5U multilayer chip capacitors manufactured from the new relaxor dielectric and the equivalent value tantalum chip capacitors.
MAINTENANCE
AND
REDUNDANCY
winning process on a tactical missile is presented here as a case study.
A datebase design for automated RAM analysis. BOB WALSH. Proc. a. Reliab. Maintainab. Syrup., 104 (1987). The widespread acceptance of computational methods fur design evaluation has helped bring product assurance into the design process. This progress is threatened by CAD/CAE tools that accelerate the design phase but do not interact with RAM software. We have designed a relational data structure that stores output from most schematic capture and CAE programs. Input for most RAM software and management information systems can be extracted directly from this structure. The complete design contains over 50 tables. Subsets of the full design have been used for three different prototypes that are already finding practical application. Quality and reliability data collection and analysis system in integrated manufacturing of computer hard-ware. H. NAKAMURA, T. HAKUCHOH and T. KAWAKAMI. Proc. 16th Syrup. Reliab. Maintainab. Japan, 42 (1986). The quality and reliability data in vertically integrated manufacturing