Hi Bill, Several years ago we stopped using 1812's on the wave solder side for all our new designs, based on recommendations of componentvendors and fellow Technetters. For older designs and for some our subcontracting customers we still have to wave solder 1812 caps, and fortunately without any reported problems. We've had our share of cracked capacitors, but that was always with smaller parts. Daan Terstegge Thales Communications Unclassified mail Personal Website: http://www.smtinfo.net >>> [log in to unmask] 01/15/04 08:26pm >>> Hello folks, I've posted this question (similar) to this forum a couple of time only to get a few responses. So, here goes...... Most data sheets for Ceramic Capacitors advise against wave soldering any surface mount ceramic caps whose size is larger than 1812. I have board designs that have ceramic 1825's on the backside. We used to wave solder them with great solder results. About a year or so ago, we received notice that we should not be wave soldering larger ceramic caps due to their susceptibility to cracking from thermal shock. I've always blamed failed caps due to handling problems. As a result, I've had to convert the second side soldering from wave soldering to reflow soldering. I've always been nervous about second side reflow "re-melting" the solder joints already on the topside so, I've always used fixtures to protect that side from "re-melting". The process works but the drawback is that any leaded parts that remain must be hand soldered. (Or re-design the board to allow intrusive soldering. I have no experience with this.) We've also improved our handling practices as well and we haven't seen any failed caps. (I still say it was the handling.) So, are most folks wave soldering any sized ceramic caps or does everyone follow the 1812 limit? I've even thought about pre-heating the board prior to wave soldering in an oven in addition to the regular pre-heat of soldering. This would help solve the problem of the steep temperature gradient. But the drawback is that the flux would be dried out before the wave. So the work around for this is to use water based organic flux that would remain active as the board passes over the wave. This remains an option but requires a lot of convincing to get approval. Thanks. Bill Kasprzak Moog Inc., Systems Group, Process Engineer --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------