I just run into this myself, however I am using Alpha 857 water soluble in a spray application. Could this be the same issue. Barry Gallegos, PE Western Electronics, LLC 110 E. 43rd st. Boise, ID. 83714 P-208-377-1557 F-208-377-9836 -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Franklin D Asbell Sent: Wednesday, September 06, 2000 6:21 AM To: [log in to unmask] Subject: Re: [TN] Solder Dross on PCB Assembly after wave solder A question...you said "...solder mask may be unsuitable...this is quite a common problem..." I've not heard of this before, of course I'm a fabricator, not an assembler, but I'm confident if our customer's were having this problem (i.e. "...this is quite a common problem") I'm sure they'd be screaming... Would you please expand on those comments, thanks. Franklin D Asbell Brian Ellis wrote: > OK, Darren. It is not easy to be categorical but I suggest you are > losing in at least one of two directions, maybe both. > > 1) So-called "no-clean" fluxes usually have relatively small amounts of > activators which tend to sublime/evaporate at temperatures exceeding ca. > 50°C. It sounds like you may simply not have enough left on the board > when it hits the wave. Try wicking down the preheat a little at a time > until the results improve, if this is the case. Perhaps a little more > flux sprayed on would help, as well. > > 2) It may also be that your solder mask is unsuitable or incompatible > with the flux or has been insufficiently cured. This is quite a common > problem, especially with some of the glossy masks and dry-film types. > > This list is not exhaustive, but you have a 95+++% chance that the > answer lies above. > > Brian > > Darren Goh wrote: > > > > > > > Hi, > > I would really appreciate some help here.. > > I am running some mixed board (thru holes with SMD) over wave.. after > > the wave, I discovered almost 80% of the boards are spatter with small > > lumps of solder dross on the under side... (between three to five > > counts of them) > > > > I am using Tamura no-clean flux and on board preheat temp is peak at > > 100degree for 10 sec. the whole preheat zone runs at 80 sec.. > > > > am using Alpha Metal solder bar ..and adopting spray fluxer > > technology, no clean process.. > > > > I hope that someone could highlight and share with me the reason (if > > possible solution) for the formulation of solder dross on the under > > side of mixed technology boards after wave. > > > > thank you very much > > Darren > > > > DID:- (65) 2493448 > > ############################################################## > TechNet Mail List provided as a free service by IPC using LISTSERV 1.8d > ############################################################## > 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 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 1.8d ############################################################## 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 Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################