Frank: One possibility is that the soldermask was not fully removed from the bottom side of the hole when processed thru the developer at the bare board fabricator. The holes hold more mask and are harder to "clean out" than the surface of the board when going thru the developer. In the developer the nozzles spray both sides of the board. If the ones that were spaying on the wavesolder or bottom side of the board were not functioning properly(low pressure, plugged, etc)they may not of completely stripped the soldermask from the hole on the bottom side. The rest of the board would be properly developed. This residual mask could result in poor or insufficient plating in the bottom side of the holes. However you would still have good plating on both top and bottom side surface pads and in the top side of the holes, as they would be clean of any soldermask residues. The result would be poor solderability on the bottom side of the hole due to poor plating and/or interference from trace amounts of residual mask and the rest of the board soldering fine. Regards Michael Barmuta Staff Engineer Fluke Corp. Everett WA 425-446-6076 -----Original Message----- From: Frank L Norman [mailto:[log in to unmask]] Sent: Monday, July 28, 2003 11:14 AM To: [log in to unmask] Subject: Re: [TN] Wave solder process issue on ENIG pwa Carrie, Yes, the bottom side SMT components were put down with chip bonder and then wave soldered. That's my question also, why did the SMT joint work out and the through hole fail so miserably, they both were subjected to the same assemble processes and then when solder joints were attempted they did not exhibit the same wetting issues. The only thing I know is that the fabrication of these PWB's were a challenge for the vendor, because of the book binding not fitting into standard tooling/processes. Regards, Frank Norman Manufacturing Support Engineer Raytheon, Space and Airborne Systems (SAS) (805)879-2745 [log in to unmask] "Morse, Carrie" <[log in to unmask]> 07/28/03 10:52 AM To: "TechNet E-Mail Forum." <[log in to unmask]>, "Frank L Norman" <[log in to unmask]> cc: Subject: RE: [TN] Wave solder process issue on ENIG pwa Frank, Did you use a "Glue/Paste" process on the SMT that is on the Wave side, or, did you get those nice fillets from the wave? IF you got them from the wave, the questions become: 1. Why nice wetting on the SMT and not on the TH pads? 2. How was the bare board processed at the Fab level? Before looking at the photos I thought the leads of the comps were contaminated, or, the profile was insufficient, or, your contact angle and dwell times were not quite sufficient. But, after looking at the photos and seeing the nice topside fillet on the TH and nice SMT fillets, I get the feeling that the plating on the bottomside of the board at the TH comps was compromised at the fab level. Maybe the resist was not sufficiently removed prior to plating. It's hard to tell from the photo, but, where there is insufficient wetting on the wave side pad, what does that section look like? What color is it? -Carrie -----Original Message----- From: Frank L Norman [mailto:[log in to unmask]] Sent: Monday, July 28, 2003 1:26 PM To: [log in to unmask] Subject: [TN] Wave solder process issue on ENIG pwa Technet, Looking for comments for the following... PWA's experienced solder wetting difficulties to plated through holes including via's during the wave solder process and are unable to be touched-up by hand. PWA's are two sided multilayer with combination of rigid board and flex circuits finished with Electroless Nickel Immersion Gold (ENIG) for a thickness of 100 microinches of Nickel and 5 microinches of Gold. Top side SMT components were reflowed and bottom side SMT were wave soldered with excellent results, but as you can see in the pictures the plated through holes on the wave soldered side had wetting issues. Interesting thing is the non wave solder side through holes have good wetting. SEE PICTURES of pwa's in question at this website. http://www.ripus.com/images/pwa/index.htm Regards, Frank Norman Manufacturing Support Engineer Raytheon, Space and Airborne Systems (SAS) (805)879-2745 [log in to unmask] --------------------------------------------------- Technet Mail List provided as a free 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/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 1.8e 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/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 1.8e 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------