In a message dated 7/26/00 2:39:33 PM EST, [log in to unmask] writes: << We are experiencing problems with soldering of PLCC's. We find that a significant number of these devices are received from the vendor with non-coplanar leads. The lack of co-planarity causes open solder joints. Investigation has resulted in the knowledge that approximately 5% of the PLCC device we receive are not within the 0.004" co-planarity requirement. We find some to be out as far as 0.012". I cannot currently define the point at which the lack of co-planarity becomes an issue. The supplier is a major manufacturer of these devices. The parts are on tape and reel. We have inspected them prior to any processing at our facility, so we know that it is not a question of in-house handling, placement, etc. 1) Does anyone else see co-planarity problems with PLCC's? 2) What steps have you successfully taken to correct this problem, and what was the result? 3) Are there pieces of equipment I can put inline to screen <*gasp*> out these devices? 4) Any assembly or processing tricks you have used successfully to compensate? Thanks, Lang x5046 >> Hi Lang! I would agree that there is something in either the testing or programming process of the devices that is causing coplanarity problems...that's been my experience anyway... Tape and reeling can also introduce problems if the tape and reel machine isn't set up properly...there are guides for the tape after the part is sealed into the carrier tape, that guide the tape up on to the reel. If that isn't set up correctly, it will bend the leads...you can see if that's the problem by looking at the pocket for each part to see if it's been deformed or not. Usually the same leads on every part will be bent. As far as being able to compensate for the coplanarity of the leads in the assembly process, as a general rule, your solder paste print will provide a fillet of 50% the printed height. So if you're seeing a coplanarity of 12-mils, that means you have to print 24-mils of paste to compensate for that....not likely. There are options on pick and place machines that will check for coplanarity, but add 5 or so seconds to each placement that does a coplanarity check (laser based usually). Thing to do in my opinion is to square your supplier up...PLCC's are normally pretty robust. To get things out that far they've been mis-handled somewhere along the line, or a machine set-up wasn't done correctly... -Steve Gregory- ############################################################## TechNet Mail List 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://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################