Don't run the acrylic through a water wash. High pressure jets typical in SMD cleaners can punch through the coating (similar to sandblasting) and delaminate it in flakes that clog filters and DI resin beds. Use a no clean paste or wire solder with no liquid flux to do the rework, then you don't need to clean. Rosin or synthetic resin may compromise application of the new coating, but that is specific to application method, coating and specific flux. At previous employers, we repaired through acrylic all the time with no problems using burning, local stripping, complete chemical stripping or mechanical abrasion to remove the coating. All worked for certain components and didn't work well on others. ARIC PARR Sr. Manufacturing Engineer Eaton Corp 1400 S. Livernois P. O. Box 5020 Rochester Hills, Mi 48308-5020 [log in to unmask] 248 608 7780 Fax: 248 656 2242 ------------- Original Text From: C=US/A=INTERNET/DDA=ID/TechNet(a)IPC.ORG, on 5/17/99 5:59 PM: To: Aric Parr@01635@Lectron_RH, EatonWHQ@CorpMail@WHQCleveOH[C=US/A=INTERNET/DDA=ID/TechNet(a)IPC.ORG], Dean Jones@01635@Lectron_RH, Luis Arevalo@Automotive Eng@AACOCarolStrmIL Hi ya'll! We just got a rework job in from a customer where we're gonna change a PLCC28 out for them, remove it and replace it with another. The board has been conformal coated with an Acrylic conformal coating (Humiseal type 1B73 I believe...). I know reworking can be done just by burning through the coating, and then cleaning up the pads real good before putting the new part back down. We're water soluble, so we're gonna have to run the boards through the cleaner to clean the flux residues...and I know that we'll damage the coating when putting it through the cleaner. On the boards that I've looked at, the coating has been compromised anyway on spots here and there just from the handling...acrylic is not too tough. I told our customer that the coating was gonna be pretty raggy looking when he got the boards back from us, and we're not in the conformal coating business. But what's bothering me, is that I think they've got some spray cans and they're gonna try and touch-up things themselves...against my strong recommendations. I think the boards should be stripped of the coating that's on there now, baked, and then re-coated. But like I said, we're not in the conformal coating business, and I've not worked much with the stuff anyway. I'm just thinking logically about it...am I sweating things too much? Thanks! -Steve Gregory- ################################################################ 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's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################ ################################################################ 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's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################