Development of ball grid array packages with improved thermal performance

To provide electronics packages with sufficient cooling during applications to secure improved reliability and performance of the packages has been one of the challenging tasks for their manufacturers and end users. Since the introduction of the standard Ball Grid Array (BGA) package, continued efforts by package developers have successively resulted in a family of thermally enhanced BGA packages. The eXtra Performance BGA (XP-BGA) package is one of its latest members developed as a cost competitive package for thermal margin. To demonstrate the effectiveness of the XP concept introduced by UTAC, this paper assessed the thermal performance for the two typical BGA families, i.e. FBGA 15x15mm and PBGA 35x35mm, by applying different thermal enhancement methods. Simulation shows that thermal resistance can be reduced by 17% and 25% for XP-FBGA 15x15mm and XP-PBGA 35x35mm respectively at still air comparing with their standard BGA versions. Package thermal performance was observed to improve even more at moving air. Three-dimensional finite volume simulations were further utilized to analyze the impact of several XP related variables on the package thermal performance. XP-FBGA 15x15mm and XP-PBGA 40x40mm Multi-Chip Package (MCP) were selected as test vehicles to study their thermal performance sensitivity to the change of design, materials, process and application environment. The development of XP-BGA achieving thermal performance comparable to that of an EBGA is realized with much lower cost and higher throughput. Package structures, CFD models, and simulation data are presented and discussed.