Hi Greg - Oh boy, did you ask a question that will have the TechNet hopping for awhile!!! When you have gold finished components & gold plated PCBs and solder them using 63/37 you run the risk of having gold embrittlement. Gold embrittlement is one of those topics that metallurgists and material engineers love to discuss because: (a) it is a very well documented phenomena, (b) gold-tin intermetallics are interesting to look at. A couple general rules of thumb to use: a) Is there enough solder volume for the gold to diffusive into? The answer to this question is almost always yes. The published literature consensus is that gold embrittlement occurs at/around 4 wt.%. b) Is the soldering operation long enough and hot enough to allow #1 to occur? This is the question that is the problem. Many times the soldering process is too short to allow the gold to totally diffuse into the solder thus leaving a thin, heavy concentration of gold-tin intermetallic where cracks will originate. I don't have any experience with using a different alloy selection to avoid the problems but hopefully some of the other TechNetters will have some good suggestions. The grainy appearance of your solder joints may be the gold-tin intermetallic particles. A good paper to read on the subject is: "The Effect of Gold on the Reliability of Solder Joints", Dr. Judy Glazer, 1991 Surface Mount International Conference proceedings. Good Luck. Dave Hillman Rockwell Collins [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: ASSY: Gold-to-Gold Soldering Author: [log in to unmask] at ccmgw1 Date: 9/30/96 9:12 PM Does anyone have experience soldering gold-plated SMT components to gold-plated PCB's using a eutectic (Sn63/Pb37) solder? The solder joints exhibit a dull, grainy appearance. Although I know that longer liquidus dwell times and a maximum reflow temperature of 220 C are typically recommended when soldering to gold, will other solder alloys perform better (i.e,, Indium alloys)? Thanks in advance, Greg Kilinski Acuson Corp. [log in to unmask] *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * *************************************************************************** *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ***************************************************************************