| Objectives | Background | Approach |
Microelectronics devices, especially hand-held portable devices, encounter an impact loading during handling and operation. Although the device may not fail immediately after one set of impact (e.g., drop on a floor), it causes permanent deformation and can weaken the strength of the device interconnects. The impact-induced permanent deformation, as a residual deformation, can cause a detrimental effect on the device reliability, and thus reduce the product life when the device is used in a normal operating condition. CALCE is currently developing a sophisticated reliability prediction model for CSP packages subjected to a mechanical shock (C00-06). The model is based on the nested finite element methodology (NFEM) and it will be used to assess life cycle reliability of the packages after being calibrated by using failure data obtained from accelerated three-point bend tests and mechanical shock/drop load tests. This two-year study proposes to generalize the model for other package architectures including flip-chip packages by documenting the impact damage quantitatively. An experimental investigation is required due to the complex nature of the loading. To achieve the goal, it is essential to develop a high sensitivity displacement measurement technique that can accommodate impact loadings; the technique should provide a submicron measurement sensitivity but it should be insensitive to environmental disturbances such as vibration, impact, etc. Moiré interferometry is an optical technique for whole-field in-plane displacement measurement with submicron sensitivity. The method has been employed effectively by the CALCE team for deformation measurements of microelectronics devices subjected to a static loading. The first year will be devoted to development of dynamic moiré capabilities by extending the current moiré capabilities into the domain of impact loading. An experimental apparatus to simulate impact loadings encountered in the actual operation will be also developed. Preliminary studies will be conducted for the first half of the second year and the results will be used to refine the experimental technique. The quantitative damage data induced by impact loading will be produced during the second half of the second year. The proposed study will calibrate the reliability prediction models quantitatively to extend its applicability, and thus to reduce calibration costs for new package architectures of future interest.