For example, let’s say you ran two orders of the same product on the same PCB assembly line and, while looking at your historical data analytics
, you realize that you had a decrease in first pass yield (FPY) of 1.9% from one week to another.
It may not seem a lot but if you look at the First Pass Defective Unit Count, you realize an increase of 42.9%!
Red flag – why did this happen? Since it could be a myriad of variables, a great way to narrow it down quickly is to analyze your Top 10 Defects. In this specific case, your AOI had an increase of 52.2% in bridging defects
and is your biggest defect.
While this does not tell you exactly what your problem is, it is still a very helpful starting point to guide your investigation. In this case, the PCB assembly factory had recently changed its solder paste – causing more bridging defects caught at AOI.
Naturally, to avoid heavy rework costs, this manufacturing company chose to return to their previous solder paste supplier. Time and materials are valuable, especially lately…Other potential problems:
Stencil condition, machine alignment, etc.