I've just read Vickie Chapman's comment to Mark's reply regarding the variation in ppm between products. It reminded of some of the other errors I've seen in thinking in the past. I work in a low volume, hi-rel shop where each product is unique, unless you build several versions of the same product with different firmware in the proms. Each product should have its own set-up sheet and unique profile parameters. This enables you to make adjustments for problem components or design features. Each CCA will thus have its own unique defect rate for the equipment, flux, state of profile development,etc... We monitor the defect rate by individual CCA, stopping when it falls outside of the expected ppm. My problem comes when management looks at the collective data for a week or month and demands to know why we had an increase. I've also been congratulated by the same management for bringing down those darn ppm's. Only, they don't mean anything unless you are building the same quantities and mix of CCAs from period to period. The biggest swings come from starting and stopping programs with the older Hi-Rel soldering specifications, or in mix of older low volume cards with newer cards. Switching from digital to power supply cards is anothr guarentee of flakey data. None of this has anything to do with the quality of the shipping product or necessarily the profitability of the process. Steve Mikell [log in to unmask] *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************