Thermally and Electrically Enhanced Wirebond BGA

Abstract

Next-generation processors continue to demand more thermal and electrical performance from the package. Frequently, devices are designed into Flip Chip (FC) packages where the previous generations were in Wire Bond (WB) because FC typically provides superior thermal dissipation and lower package electrical parasitics than WB packages. However, FC packages usually have higher costs for mid-range IO (500–800). An Enhanced WB BGA package has been designed with improved thermal and electrical performance compared to the industry standard TEPBGA-2 (Thermally Enhanced PBGA type 2). The 500μm barrier of mold compound between the die and heatspreader in the TEPBGA-2 is a major impediment to heat flow out of the package. By contrast, the Enhanced WB package uses post-mold attachment of a heat spreader that is adhesively bonded to the mold cap and thermally coupled to the die using a 40μm TIM (thermal interface material). Improvements to substrate design rules and the die attach process that enabled the Enhanced WB design to shorten bond wires by 40% and improved electrical performance. Package thermal resistance, Theta-Ja, was verified by simulation and measurement to be 3C°/W lower than TEPBGA-2, that dissipates up to 15W in some end-use applications, approximately 2× the performance of TEPBGA-2. DDR set-up and hold time showed 30ps improvement by both simulation and measurement. This paper will present the package design, thermal and electrical simulation and measurement results.