Kathy, How far off from 183 degrees C were the other solder pastes? When I look at the tin lead phase diagrams in my text books, it looks like the true eutectic point is at 61.9 wt% tin and 38.1% lead. If a vendor supplied solder that was actually Sn63Pb37, the melt point should be slightly higher than 183 degrees C. Maybe someone out there knows how much the melt temperature would be affected - It's been a while since I used the lever rule on a phase diagram. Would this small variation in composition be enough to explain your test results? Just curious. Dave Anderson Medtronic, Inc. >>> Kathy Palumbo <[log in to unmask]> 03/24/98 07:17pm >>> Ed, We recently did some Solder Paste qualification testing. Part of the test was to check the eutectic point of the solder. Out of the ten solder pastes we evaluated, there was only three that melted at the right eutectic point (183 degrees C). They were OMG (formally known as SCM), Qualtek, and Alpha Metals. I am not sure what the metal content was of the other 7 brands, but it was not Sn63Pb37. I wonder if this would be a sign of using recycled solder? We did recently change our solder paste supplier, and as a result we are seeing an improvement in our first pass yields. They have shot up a full 1 to 1.5%. Our over all yield is now hovering around 98.8% to 99.1%. Kathy Palumbo > ---------- > From: Ed Cosper[SMTP:[log in to unmask]] > Sent: Tuesday, March 24, 1998 11:43 AM > To: [log in to unmask] > Subject: [TN] FAb: Solderlevel > > I have been reading some articles lately on effects different solder > has on uniformity ( flatness ). I have also read where some solder may > be being sold as "pure" solder but in actuality the solder was blended > with recycled solder resulting in organic contaminates. Based on this > information I have 2 questions. > > 1. Has anyone found improved results by changing the solder supplier? > 2. If positive results where found, what solder did you change to? ( > Please respond to this question off forum so as not to > invoke inappropriate advertisement) > > All helps is appreciated. > > > Ed Cosper > Director Quality Assurance and Engineering > Graphic Electronics Inc. > > ################################################################ > TechNet E-Mail Forum 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://jefry.ipc.org/forum.htm) for > additional information. > For the technical support contact Dmitriy Sklyar at [log in to unmask] or > 847-509-9700 ext.311 > ################################################################ > ################################################################ TechNet E-Mail Forum 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://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################ ################################################################ TechNet E-Mail Forum 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://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################