MITIGATION STRATEGIES TO ENHANCE PRODUCT-LEVEL BGA SHOCK PERFORMANCE FOR VARIOUS HEAT SINK ATTACHMENT METHODOLOGIES

摘要

The confluence of explosive demands for faster data rates and more functionality because of the advances of silicon fabrication technologies has resulted in larger and higher density ASIC chips, hence making thermal management at the product level more challenging than ever. To be more effective in controlling the operating temperature of critical components, larger and/or heavier heat sinks (HS) are more commonly seen today in high-end network products. One of the major concerns with regards to HS on larger Ball Grid Array (BGA) components is mechanical shock reliability performance during manufacturing, assembling, product shipping, and installation. This study investigates the maximum PCB strains near large BGA assemblies under different HS attachment and at various weights. A BGA assembly has been excised from a product to create a test vehicle (TV) that is similar to JEDEC standard component-level qualification shock TV. The TV is tested with different weight metal blocks that were mounted on the BGA component to simulate different HS: 157g for Aluminum HS and 744g for large Copper HS. A design of experiment (DOE) is executed to capture key interactions between the HS weight and attachment method. The shock testing results have been applied to guide the development and enhancement of product-level shock performance. Subsequent product-level packaging drop tests proved the effectiveness of the enhancement strategies. The findings of this study are helpful in developing guidelines for designing HS attachments to enhance product-level shock performance and providing empirical insights for numerical modeling benchmarking.