Thermal and electrical performance and reliability results for cavity-up enhanced BGAs

A new cavity-up enhanced flex-based BGA package, which adds an integral copper interposer between the die and the flex, expands the options available to the electronic industry for increasing reliability, thermal and electronic package performance, offering improvements compared with many prominent flex-based CSP and BGAs. For board-level reliability, CTE measurements of this enhanced BGA using a moire fringe technique predicted thermal cycling performance similar to μBGA and superior to rigid organic laminates, ceramic CSPs and flex-only packages. Package-level reliability testing of the enhanced BGA has identified some common assembly die attach and overmold materials combinations that have performed to JEDEC Level 1 in moisture resistance tests. Thermal computational fluid dynamics (CFD) modeling of the enhanced BGA package with the interposer showed substantially lower junction temperatures in two application environments, as compared to the analogous flex-based package construction without the interposer. Electrical analysis using a boundary element electromagnetic field solver to extract fundamental electrical circuit parameters over a broad range of operating frequencies also predicted electrical performance benefits for the enhanced BGA with interposer versus the same construction without the interposer