I would like help in establishing what is a feasible PPM reject rate from a typical SMD line.
As a reference an SMD line consists of, solder paste printer, chip component placement, pick and place IC components and reflow.
What is a benchmark standard, 100ppm, 50 or 20ppm ? typical rejects are; missing components, trayed components, tombstoning, non wetting, bridging, etc.
second part to the question is where is this PPM detected, is it at AOI or at visual inspection by operator.
Reason being, I am concerned to base all my PPM data from an AOI machine where it can give a false sense of security. A poorly programmed AOI can give high rejects, but this does not neccessarily mean that the placement and reflow is poor, mearly the AOI is rejecting good parts. And visa-verse
Hello , In our case we take the results from the repair station. Each test station has its own repair station so from there we count the process defects : placement and printing. The formula used to calculate PPM = DEFECTS / (PARTS PER BOARD x UNITS TESTED) x 1000000 . Now our PPM level is 7 for placement and 10 for printing , the goal is 9 PPM from both processes. The configuration recomended is to have an AOI after solder paste printer and other AOI before oven and TPM strong program.