As the amount of electronics applications, density, and I/Os continues to increase and the packaging area continues to decrease in automotive electronics, advanced packaging technologies suitable for high-volume, low-cost applications need to be considered. The development of automotive electronic packaging technology depends on several key factors, e.g., location environment package size and density, supplier technology, and reliability target. Some examples are shown in Table 1. In general, automotive electronic packages are subjected to various levels of environment induced loadings, depending on the location of installation. For example, the temperature can range from -40”C to 150”C and the vibration may reach as high as 30 G at 20-2000 Hz under the hood, while in the passenger compartment the temperature range may only be -40°C to 85”C, with vibration of 4-5 G. Direct applications of some advanced or emerging packaging technologies used in other industrial sectors, e.g., computer, consumer electronics, or telecommunication to automotive may result in severe reliability or environmental issues due to much stringent automotive requirements. Examples of these applications include fine-pitch surface mount technology for microprocessors and memory components located under the hood, lead-free solder alloys driven by government regulations and legislation applications in high power electronic systems, such as electric vehicle, alternator, active suspension, or electric power assist steering. Ball Grid Array (BGA) packages are being considered as a replacement for peripheral Plastic Quad Flat Packs (PQFP) for high I/O applications in future automotive electronics. Various types of BGA were developed to meet specific needs, e.g., plastic (FBGA), ceramic (CBGA), and TAB (TBGA), Their design manufacturing and reliability issues have been extensively studied and documented e.g., Lau (1995), Darveaux and Mawer (1995), Darveaux et al. (1995), Freyman and Petrucci (1995), Chen et al. (19%), Clech (1996), Economou (1996), Hong et al. (1996), Jung et al. (1996), McCluskey et al. (19%), Mescher (1996), Munamarty et al. (1996), Lee and hl (1997), and hl and Pao (1997). A comparison of conventional BGA packages and PQFP is summarized in Table 2. One major concern of the BGA package is its reliability when subjected to thermal fatigue loading. Several failure modes have been observed previously, such as printed wiring board (PWB) warpage, die cracking, “popcorning”, solder cracking, and delamination inside the package. Some of the failure modes are related to the manufacturing process as well (for example, reflow). Design parameters related to thermal fatigue reliability of BGA packages are identified based on data published in the literature and are listed in Table 3. The present paper f-s on the reliability analysis of a cavity down BGA package. The package was selected from commercial products and modeled with a full 3D, nonlinear and time dependent finite element analyses.