The simple version of a formula is this: [(number of defects) / (number of opportunities for a defect)] X 1000000 If you count a defect for each lead that is off of the pad, then count an opportunity for each lead. If you have a QFP that is off of the pads and you count that as one defect for a misaligned component, then only count the component as one opportunity. Don't cheat yourself in either direction. If you count every pad in your opportunity number then count every lead overhang in your defect number. Jon Moore TRW >>> <[log in to unmask]> 04/28/98 04:41am >>> Dear colleagues We have some argues regarding PPM calculations, For an example: for placement station of automatic SMT components, do we have to count the soldering pads or only the components. If only the components its not the same level of difficult for capacitor and fine pitch. The same question is for dispensing machine of SMT glue. Please E Mail me the general formula for PPM calculation. Thanks and Best Regards Rokah Reuven IPC Member ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################ ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################