UM16 is the first automotive product for smart driving manufactured in ST Philippines, and a key product to support the latest features in the parking assist system of all modern cars. Failure to achieve stringent quality requirements will result in car accidents and would mean a pull-out of the automotive business in ST Philippines.
UM16 Assembly yield is the lowest at 98.04% among other packages and is not meeting the customer yield target of 99.5%. The top defect contributor for die attach is insufficient epoxy at 1360 PPM during product release in April 2018. To improve the overall UM16 assembly yield, we need to bring down insufficient epoxy at the die attach process from 1360 to 300 PPM by the end of Q4 2018.
Applying Six Sigma DMAIC methodology and its applicable statistical tools, we trimmed down the 14 key process input variables or potential causes into four major causes as statistically significant true causes of insufficient epoxy, which are: clogging of dispensing nozzle; prolonged epoxy staging time; unoptimized break tail parameter; and, ineffective detection at pre-bond inspection.
The team came up with error-proofing solutions to resolve and reduce the insufficient epoxy issue. The four innovative and breakthrough solutions we implemented are: auto nozzle cleaning every 10min; 60min allowable epoxy staging time; optimized break tail parameter; and installation of ultra-bright light with double sidelights at pre-bond inspection. These were key in reducing insufficient epoxy to an average 2 PPM. This gained the company an annualized cost savings of $16.86k and cost avoidance of $205k, instead of buying a new machine model.