Hi Bill, It looks bad.The solder on those pads is heavy contaminated prior to wave soldering. You should examine unprocessed boards.This kind of appereance might be results of lot of things: - incident splash of chemicals corrosive to tin/lead ( for example those based on sulfuric acid) somewhere between HASL and your assembly line. - unwashed chemicals from HASL precleaning line - poor etch resist removal ( tin or tin/lead from pattern plating) -dross in HASL pot - rework ? ( results of unwashed aggresive flux used for rework) I do not think,that this is results of LPI residues - if those are present on the pads,the result is lack of coverage Edward Edward Szpruch Eltek , Manager of Process Engineering P.O.Box 159 ; 49101 Petah Tikva Israel Tel ++972 3 9395050 , Fax ++972 3 9309581 e-mail [log in to unmask] > -----Original Message----- > From: Stephen R. Gregory [SMTP:[log in to unmask]] > Sent: д аевеси 02 2001 17:45 > To: [log in to unmask] > Subject: Re: [TN] Process Problem vs Board Problem > > Hi Bill! > > In looking at the pictures, I must say that the HASL does look kind of > strange. It almost looks like the HASL is just adhered in that ring around > > the pad, and the rest of the pad and barrel almost looks like tin with no > HASL covering?!? > > Do you remember if the boards looked the same back when you had no > problems > as they do now? > > Maybe somebody else has a clue... > > -Steve Gregory- > > > > > 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 ---------------------------------------------------------------------------------