Issue link: https://iconnect007.uberflip.com/i/1512467
DECEMBER 2023 I SMT007 MAGAZINE 63 Parts reel change validation: Humans make mistakes. We have installed pre-flow AOI to check rotations and 100% compliant place- ments. is was a simple ROI measure of your rework on double-sided high, populated small- size parts when you apply an iron to fix some- thing. I can wipe a board, reclaim the expensive parts, and re-run it cheaper than the rework adventure. Human interventions: e new package sizes leave little room for errors, and the oper- ators/process technicians always modify pro- grams with good intentions, but the programs have very open-ended subjective inspection parameters. Here's a good example: A 1% con- trast adjustment on a standard X-ray camera can swing the voiding scale more than 10%. Sleep well, quality engineers, now that you know. Exception calls: ese are the calls that the AOI has been programmed to ignore or bypass because the AOI and 3D camera remodeling can't produce a predictabl y cor- rect result. In these situations, the industry does one of two things: Whistle through the graveyard and give it a false call pass or flag the PCB as a failure to have a manual visual conducted offline; when that's done, you need to run it through a final go validation. standards which said that for parts placed per hour in a contract manufacturer with a high mix, low volume, 19–21% overall line up-time is excellent. Do you realize that's like the Men- doza Line in baseball where you get sent back to the minors? We identified vital waste problems that needed a fix: line change-over time, line stall time, parts reel change validation, human intervention, exception calls requiring valida- tion aer the final AOI, and standardizing all go/no-go calls the same across all AOIs. Let me describe these in more detail. Line change-over time: Do you have the correct pit crew to win the race? e indus- try is first coming to grips that high mix can be overcome with family set-ups to maximize feeder positions, a screen print that could host several screens that will conduct an auto change-over to the new screen with the new job, so now we have a 4.0 standard started to make line changes automatically up and down the line. Line stall time: Someone needs to coin a catchphrase for this one. You can't achieve a placement time percentage if every occasional fault stops the line. Aer each optical inspec- tion, we installed inline stackers to push the fault to the side and keep the line moving.