Technetters': Thanks go out to all who have responded so far.I will add a caveat and state that LPISM is not an issue because the circuit boards do not have any solder mask on them. The boards are constructed in a way that all the traces are on the internal layers and only the pads are on the external surfaces. I am re-running the post with the hopes of soliciting more responses, however I will be out of the office next week (8/6-8/11) so I will not be able to report on any findings until 8/13 or shortly thereafter. Thanks go out to all for their two-cents worth. Bill Kasprzak Moog Inc., Electronic Assembly Engineering RE-RUN ...... > Technetters' > > I've recently run into a problem with Wavesoldering some circuit boards > where I am having problems getting topside solder joints. The process that > I'm running has the topside of the board at 195-200 F just prior to the > solder wave. My conveyor speed is 4.0 fpm. My fluxer is a spray fluxer. > The > board is a .062 - 6 layer board that has an aluminum heat sink on it. I > feel > that my process is set correctly. > > The original process that previously used on these boards was very > successful when we used an OA water soluble flux. This process was on that > I > qualified many years ago to J-Std-001A for Class 3 assemblies. > > On these circuit boards, I'm trying to use a No Clean Lo Activity level > flux > that is water washable. Because I have new equipment for wavesoldering, I > was hoping to not have to do a re-qualification process for our level 3 > assemblies. Because our new equipment has much better controls than our > old > equipment I thought that it would be easy to solder these boards with an > LO > active flux. Well, my initial pass has been a disaster so far. There are > three pictures that I'm looking for comments on. They are located on > Steve's > Webpage at http://stevezeva.homestead.com. (A thousand thanks go out to > Steve Gregory for providing a site for posting the pictures.) Two of the > pictures, called Bare Pad and Bare Pad2 show a condition that I can > describe > but I don't know if this condition has a name. In those pictures, there is > a > heavier coat of solder on the pad, but it seems to form a concentric ring > on > the pad.The extremities of the pads, both toward the outside and the > inside, > show a tinned surface but it appears to be much thinner. To me, it seems > like these thin areas do not readily solder. It seems like this thin area > is > barrier that can only be overcome with a very strong OA flux. This may > explain why I did not have a problem before. The other picture shows > another > condition that I see in various places on the bare board where there are > protrusions on the inside of the PTH's. This appears to be trapped > volitiles > that were being expulsed during the HASL process. > > I'm trying to determine if I have a board problem or a process problem. > > Is it unreasonable for me to think that this board can be soldered with a > no-clean (but water washable) LO activity level flux? > > Any help or comments would be greatly appreciated. > > Bill Kasprzak > Moog Inc., Electronic Assembly Engineering > --------------------------------------------------------------------------------- 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 the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ---------------------------------------------------------------------------------