Paul Just a couple of remarks: 1. if the die bond is failing, then this is a component manufacturing issue. This should not happen, even if the component is letting water in. 2. if you are using 63/37, 260°C seems to me excessive. I would up the preheat to, say, 110°C topside to make sure all the water in the flux solvent has evaporated, including what has gone through to the topside and reduce the wave temp to, say, 240 - 245°C (less thermal shock). You may need to adjust the conveyor speed slightly, as well. Brian Paul Truit wrote: > > We are experiencing a problem related to an Optocoupler. I wanted to > see if anyone had any ideas as to the whys. The IC's have failed > intermittently in the field. > > Specifics: > Mixed technology board. The Opto in question is Through Hole. It is > Hand inserted. The board is processed using a VOC free OA flux that is > sprayed on with a spray fluxer. 2 bottom side convection pre-heaters > bring the board up to a 96°C (204°F) top side board temperature on a > conveyor that is set for 4'/min in a wave solder machine. Wave solder > pot is at 260°C (500°F). The maximum part lead temperature is > 164°C(327°F) for 6 seconds. The board transitions into an aqueous > cleaner. The board has 6 feet to cool off before hitting the water. > This is 1.43 minutes. The water temp is set for 63°C(145°F). and the > belt speed is set for 4'/ min. 2 dryer sections dry the boards off. > Cooling of the part is a slope of -1.63°C/sec(-35°F/sec). > > The optocoupler's pass a functional test. They then fail intermittently > in the field. Failure analysis of the IC has shown an inadequate die > bond between the Lead frame and the silicon die. 2 different date codes > have been found to have failed. > > There has been a different EMS making a similar board using identical > part numbers that these boards have not failed. What appears to be > different is we clean, they don't. Any issues with aqueous cleaning and > Opto's? And this process causing the lead frame and die separation > issue? > > -- > Paul Truit, Mfg. Eng. > RBB Systems, Inc. > 4265C E. Lincolnway > Wooster, OH 44691 > Ph. (330) 567-2906 ext 514 > Fax (330) 263-5324 > Email: [log in to unmask] > > --------------------------------------------------------------------------------- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL > To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest > Search the archives of previous posts at: http://listserv.ipc.org/archives > Please visit IPC web site http://www.ipc.org/html/forum.htm for additional > information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 > --------------------------------------------------------------------------------- --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------