ASSEMBLY PROCESS DEVELOPMENT FOR A 14MMX14MM BOND VIA ARRAY (BVA) PACKAGE-ON-PACKAGE (POP)

摘要

Package on Package (PoP) components offer a low cost, high performance solution for stacking of a logic device with memory. There are a number of challenges in the final assembly at the Electronic Manufacturing Services (EMS) facility. An assembly process has been developed for a Bond Via Array (BVA) PoP package having 14mm x 14mm body size with a topside memory module and a bottom logic module. In this PoP design, the solder ball interconnects between the top memory module and bottom logic module has 5 outer rows having 1020 I/O with a 0.24 mm pitch. The solder ball interconnects between the bottom logic module and the PCB is a patterned array having 916 I/O with a 0.4mm pitch. A special focus on this work was the optimization of the stacking process of the memory solder balls to make good interconnections to the BVA wires protruding from the bottom logic package. Topics covered for process evaluation will be vision systems, yield, package alignment and placement, voiding and major-defect identification such as bridging, opens-insufficient solder. Process issues related to solder volume, substrate coplanarity and x-ray inspection techniques will be presented. Finally design recommendations, reliability data and rework techniques will be reviewed.