In a message dated 06/27/2000 1:32:57 PM US Eastern Standard Time, CSLPAT writes: > > Hi Technet, I have a question for those that are involved with component > manufacturing. Well, we don't manufacture components, but we analyze a bunch. > > What type of flux is used for preparing leads for tinning? You would get as many answers to this one as you have component manufacturers. Most use a fairly active flux, say a type M or type H flux. Several use sulfuric acid or methane sulfonic acid a oxide strippers. The more aggressive material allows them to process at a faster speed. > Also is there anywhere that chlorine is used in this process? Where would chlorine come > from if not from the manufacture? It depends on the materials chosen. Some component manufacturers use hydrochloric acid as the etchant. I think that you will find chlorine on components about as common as nitrogen in air. The stuff is everywhere. > > We analyzed some of our raw goods with a SEM and noticed that there was > chlorine present in the junction of diodes and also on the leads by the > glass / slug interface A SEM tends to be more qualitative than quantitative. It is not surprising that a SEM shot picks up chlorine. How strong a peak was it in relation to the other peaks? We have seen a few cases where the seal material is not glass, but an epoxy material. Depending on the construction techniques, you may have the aggressive material absorbed or trapped in the interface material, which then causes lots of corrosion problems when mixed with moisture. Doug Pauls CSL ############################################################## 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 Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################