A comparison of a single tier and double tier enhanced PBGA package design

This paper compares the advantages of two alternate enhanced Plastic Ball Grid Array (PBGA) designs. The paper concentrates on two 479 I/O count BGA packages that can be used for high frequency, high performance applications. The first design is a cavitated, multi-layer package with multiple power and ground planes, two wire-bonding tiers, and a copper slug. The second is an enhanced version of the single core PBGA with one power and one ground plane, one wire-bonding tier, and a copper slug. The two packages were designed to be interchangeable (i.e. carry the same silicon device). The comparison includes electrical properties, mechanical stress levels, substrate manufacturing processes, and assembly processes. The conclusion is that the main advantage of the one tier design is better substrate manufacturability and the advantage of the two tier design is easier final assembly. The designers should select the design that fits into the strength of their organization- either package manufacturing or assembly.