Loan, Are you sure this is really a cold solder joint or is it just a dull looking solder joint? It also sounds like you are having some problems with getting good topside fillets. This all sounds like it could be a solderability problem with the components in question or a fluxing problem. I don't understand the 2 passes though. Why wouldn't you flux, preheat and solder in 1 pass? Ken Kirby Speedline Technologies (Embedded image moved "Tempea Ioan" <[log in to unmask]> to file: 10/04/99 03:45 PM pic30847.pcx) To: [log in to unmask] cc: (bcc: Kenneth Kirby/ElectrovertUS/Cookson) Subject: [TN] Cold solder Hi Technos, I'm in big trouble with a backplane. It's a 13.5"x19.5", 3.7mm thick. The connectors are disposed in parallel lines, forming two columns a the two extremities. In the middle we have no components. In between the connectors there are some TH caps and resistors. ______________________________ ______ ______ I ______ ______ I ______ ______ I ______ ______ I .. .. .. ______ ______ I _______________________________ I For a long time the soldering was OK, with small problems in the four corners ( a couple of holes not 100% full). For about a week or so, the solder joints of many caps or resistors present cold solder. There are no significant cold solder problems with the connectors, which present though a little less wetting (some of the fillets are not what they used to be). The question is: why do I get the cold solder and how can I get read of it? We use : - no-clean technology - Multicore Sn63 solder - Multicore X33 flux - strong radiation preheating ( two top preheaters at 700F and two bottom at 750F); we spent a lot of time tweaking to avoid damaging the board - two passes, one for fluxing only, no wave, the second one right after with no fluxing, but with wave - no chip wave (that's what I have, hehehe), just omega on our Electrovert Econopak II Any help would be greatly appreciated. Thanks, Ioan ############################################################## 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 Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################