Developing a methodology to link printed circuit board assembly yield targets to commodity group quality goals

Abstract

The increasing complexity of high-end routing products, a highly diverse product mix, and continually demanding quality requirements have intensified the challenges faced by Cisco. Primary among these is managing the broad array of suppliers to ensure that the parts they are delivering meet the quality needs of the end product while balancing this with the need to remain cost competitive. Because components are often used across many product lines, it is can be difficult to determine exactly how an improvement to the quality of an individual component will impact Cisco's overall yield metrics. This thesis establishes a methodology for linking component quality to assembly-level yields. The component level quality is measured in Defective Parts Per Million (DPPM) at the Commodity Group level, and PCBA Yield is measured as the percentage of boards which meet Cisco's Six Sigma yield targets. The proof of concept for such an analytical link shows that these two metrics can be analytically related, and furthermore can be used to ensure that the effort expended to improve DPPM is optimally targeted to have an impact on assembly-level yields.