Reliability of CGA/LGA/HDI Package Board/Assembly (Final Report)

Package manufacturers are now offering commercial-off-the-shelf column grid array (COTS CGA) packaging technologies in high-reliability versions. Understanding the process and quality assurance (QA) indicators for reliability are important for low-risk insertion of these advanced electronics packages. The previous reports, released in January of 2012 and January of 2013, presented package test data, assembly information, and reliability evaluation by thermal cycling for CGA packages with 1752, 1517, 1509, and 1272 inputs/outputs (I/Os) and 1-mm pitch. It presented the thermal cycling (-55C either 100C or 125C) test results for up to 200 cycles. This report presents up to 500 thermal cycles with quality assurance and failure analysis evaluation represented by optical photomicrographs, 2D real time X-ray images, dye-and-pry photomicrographs, and optical/scanning electron Microscopy (SEM) cross-sectional images. The report also presents assembly challenge using reflowing by either vapor phase or rework station of CGA and land grid array (LGA) versions of three high I/O packages both ceramic and plastic configuration. A new test vehicle was designed having high density interconnect (HDI) printed circuit board (PCB) with microvia-in-pad to accommodate both LGA packages as well as a large number of fine pitch ball grid arrays (BGAs). The LGAs either were assembled onto HDI PCB as an LGA or were solder paste print and reflow first to form solder dome on pads before assembly. Both plastic BGAs with 1156 I/O and ceramic LGAs were assembled. It also presented the X-ray inspection results as well as failures due to 200 thermal cycles. Lessons learned on assembly of ceramic LGAs are also presented.