Development of BGA solution for the IBM PowerPC 970 module in Apple's Power Mac G5

Apple's Power Mac G5 systems use either one or two IBM PowerPC 970 chips. Initial systems built with the PowerPC 970 64-bit processor run at speeds up to 2.0 GHz. These chips are packaged on IBM ceramic BGA (ball grid array) modules. The high performance modules dissipate high power, which presents new packaging challenges. One of these challenges has been addressed successfully by improving the thermo-mechanical integrity of the solder interconnections between the chip carrier module and the organic processor board. The PowerPC 970 chip dissipates high power in a small area and is aggressively cooled using a state-of-the art heatsink design. This paper describes how through a cooperative effort between Apple and IBM, a BGA reliability enhancement was evaluated and successfully implemented. Use of BGA underfill strengthens the BGA connections between the processor module and the processor card and increases long term reliability performance affected by creep and cyclic fatigue.