Grant; I found this happen when we changed from 4% solids to 2% solids, solder balls start appears at one specific area in the board, and we wouldn't be able to eliminate the problem, I only reduced it by increasing the pre heating temperature.The situation was exactily the same, I changed only the flux and the other parameters were held constant. Thanx Jorge Dourado de Santana Maintenance / Process Engr Microtec - Brazil > -----Original Message----- > From: Grant Emandien [SMTP:[log in to unmask]] > Sent: 20 de Agosto de 1999 08:51 > To: [log in to unmask] > Subject: [TN] Solder/Flux/ICT Issue > > Hi again, > Thanks for all the input as it has now directed me towards fluxes (and > control thereof) and ICT. > Leading from one of the members advice of low residue flux I stumbled > across > this Kester comment: > 'Flux selection does have some play as to the occurrence of solder balls. > A > rule of thumb is that the lower the solids content of the flux is the more > solder balls will be noted when all other parameters are held constant. > This > is sort of a dilemma for us as a flux manufacturer in that if we increase > the solids content, we will more than likely have an adverse impact on > probe > testing of final soldered assemblies. The aesthetics of the final soldered > assembly will also be affected as you can imagine.' This was posted in > 1993 > so any idea on what has since transpired and is this statement still valid > wrt the solids content? > Geez, my research thusfar has brought an array of variables to this party > such as test pin profiles and type, gold plating vs gold alloy, pin base > material hardness, spring force etc. on the ICT aside. Nevertheless it is > now beginning to get interesting. > As a comment, I hope my research drives me away from introducing another > process i.e. cleaning of assemblies hence and control of flux effluent (we > are coincidentally reviewing ISO14000) etc. and rather focus on improving > the existing process i.e. flux residue reduction (without cleaning) and > ICT > issues. > Thanks again to all, > Grant > > ############################################################## > TechNet Mail List 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 web site (http://www.ipc.org/html/forum.htm) for > additional > information. > If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or > 847-509-9700 ext.5365 > ############################################################## ############################################################## TechNet Mail List 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 web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################