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Increased use of sensors and controls in automotive applications has resulted in significant emphasis on the deployment of electronics directly mounted on the engine and transmission. Increased shock, vibration, and higher temperatures necessitate the fundamental understanding of damage mechanisms, which will be active in these environments. Electronics typical of office benign environments uses FR-4 printed circuit boards (PCBs). Automotive applications typically use high glass-transition temperature laminates such as FR4-06 glass/epoxy laminate material ([T.sub.g] = 164.9[degrees]C). In application environments, metal backing of printed circuit boards is being targeted for thermal dissipation, mechanical stability, and interconnections reliability. In this study, the effect of metal-backed boards on the interconnect reliability has been evaluated. Previous studies on electronic reliability for automotive environments have addressed the damage mechanics of solder joints in plastic ball-grid arrays on non-metal-backed substrates (Lall et al., 2003, 'Model for BGA and CSP in Automotive Underhood Environments,' Electronic Components and Technology Conference, New Orleans, LA, May 27-30, pp. 189196; Syed, A. R., 1996, 'Thermal Fatigue Reliability Enhancement of Plastic Ball Grid Array (PBGA) Packages,' Proceedings of the 1996 Electronic Components and Technology Conference, Orlando, FL, May 28-31, pp. 1211-1216; Evans et al., 1997, 'PBGA Reliability for Under-the-Hood Automotive Applications,' Proceedings of InterPACK '97, Kohala, HI, Jun. 15-19, pp. 215-219; Mawer et al., 1999, 'Board-Level Characterization of 1.0 and 1.27 mm Pitch PBGA for Automotive Under-Hood Applications,' Proceedings of the 1999 Electronic Components and Technology Conference, San Diego, CA, Jun. 1-4, pp. 118-124) and ceramic ball-grid arrays (BGAs) on non-metal-backed substrates (Darveaux, R., and Banerji, K., 1992, 'Constitutive Relations for Tin-Based Solder Joints,' IEEE Trans-CPMT-A, Vol. 15, No. 6, pp. 1013-1024; Darveaux et al., 1995, 'Reliability of Plastic Ball Grid Array Assembly,' Ball Grid Array Technology, Lau, J., ed., McGraw-Hill, New York, pp. 379-442; Darveaux, R., 2000, 'Effect of Simulation Methodology on Solder Joint Crack Growth Correlation,' Proceedings of 50th ECTC, May, pp. 1048-1058). Delamination of PCBs from metal backing has also been investigated. The test vehicle is a metal-backed FR4-06 laminate. The printed circuit board has an aluminum metal backing, attached with pressure sensitive adhesive (PSA). Component architectures tested include plastic ball-grid array devices, C2BGA devices, QFN, and discrete resistors. Reliability of the component architectures has been evaluated for HASL. Crack propagation and intermetallic thickness data have been acquired as a function of cycle count. Reliability data have been acquired on all these architectures. Material constitutive behavior of PSA has been measured using uniaxial test samples. The measured constitutive behavior has been incorporated into nonlinear finite element simulations. Predictive models have been developed for the dominant failure mechanisms for all the component architectures tested. [DOI: 10.1115/1.2804086]

Portable electronics is subjected to extreme accelerations in shock and drop impact. Product development cycle times and the cost constraints often restrict the number of design variations tested for drop robustness prior to identification of the final configuration. Simulation models capable of predicting transient dynamics can provide valuable insight into the design reliability under shock environments. In this study, explicit finite-element models have been used to study the transient dynamics of printed circuit boards during drop from 6 ft. Methodologies for modeling components using smeared-property formulations have been investigated. Reduced integration element formulations examined include shell and solid elements. Model predictions have been validated with experimental data. Results show that models with smeared properties can predict transient-dynamic response of board assemblies in drop impact fairly accurately. High-speed data acquisition system has been used to capture in situ strain, continuity, and acceleration data in excess of 1 x [10.sup.6] samples/s. Ultra-high-speed video at 40,000 fps has been used to capture the deformation kinematics. Component types examined include plastic ball-grid arrays, tape-array ball-grid array, quad-flat-no-lead package, and conduction-cooled ball-grid array. Model predictions have been correlated with experimental data. Impact of experimental error sources on model correlation with experiments has been also investigated [DOI: 10.1115/1.2804085]

Reliability models for physics-based temperature modeling should take into account the impact of temperature acceleration on microelectronic-device failures. Designers must not lower the temperature in an attempt to improve reliability. A physics-of-failure approach is a good alternative to both the Arrhenius relation and the Mil-Hdbk-217 approach to reliability. The activation-energy based models produce misleading results, since the weighted activation energy is highly sensitive to the relative dominance of the failure mechanism.

A novel electromagnetic resonance-based methodology for wire bond interconnects is efficient and quick in defect detection than the existing method of wire bond pull test. This technique, which simulates operational stress more accurately, helps assess the bonding parameters and functions as on-line process controls. Test coupon and circuity, which pass alternating current through the wire bonds, are not necessary for this test technique.

Derating involves the use of an electronic device in a narrower environmental and operating scenario than manufacturer designated limits. It is a two-step process wherein a rated stress value is first determined from a device manufacturer's databook, after which some reduced value is assigned. A new methodology is needed to ensure both safe and reliable product development amidst derating. Two key elements of such a method are to follow manufacturer derating guidelines whenever the electronic part us used within manufacturer-specified limits and to follow stress management techniques when the device is used beyond manufacturer specifications.