HI Jason! You can relax a little - your situation isn't as bad as it could be! There have been some very complete discussions on gold embrittlement on Technet so I would recommend you look at those past discussions. Here is a Reader's Digest version. There are two rules of thumb you need to be concern with: a) is there enough solder volume present in the solder joint configuration to avoid having the gold content be in excess of 3-4 %?; b) is the soldering process used to create the solder joints hot enough/long enough to allow for the gold to diffuse equally throughout the solder joint (e.g. you don't want any segregation zones). The details you provided show that you are right on the edge of having too much gold content in the solder joint which will create the AuSn4 gold/tin intermetallic which is the source of the solder joint embrittlement even if you have the soldering process tuned perfectly. You have a couple of options - either increase the solder joint volume or have the components pretinned. Gold diffuses into solder at an amazing rate (roughly 40 microinches per second depending on who's diffusion data you choose) so using a specific geometry form (a flatter joint versus a bulbous joint) is not a value added exercise. Most folks use the pretinning option to avoid having problems. Good Luck. Dave Hillman Rockwell Collins [log in to unmask] JASON CROSS <[log in to unmask]>@ipc.org> on 11/07/2001 04:27:54 PM Please respond to "TechNet E-Mail Forum." <[log in to unmask]> Sent by: TechNet <[log in to unmask]> To: [log in to unmask] cc: Subject: [TN] Gold Embrittlement Hello all, I have a case that recently came up questioning possible gold embrittlement in solder joints. I was wondering if I could bounce a few numbers off this forum and see what all of you think. Any help or reference material would be great. Ceramic 4 lead oscillator. CuNiAu lead finish. Component gold plating thickness specs are 12 to 40 microINCHES of gold. (I realize that this is quite high) Calculations indicate varying % gold by volume of solder to be between 1.36% and 2.28%, all the way up to possibly as high as 3.13% Do you know what the acceptable gold volumes are and the impact to long term reliability? Increasing the volume deposited might only make the solder wick up further along the lead, pulling more gold into the joint. This probably wouldn't really help in this particular case. Would increasing the pad size AND solder volume (hence trying to minimize forcing solder up the lead but rather keeping it flat on a larger surface) help? Would the gold spread evenly to the entire solder volume or still concentrate near the lead? Any help or reference material would be great! Regards, -- Jason Cross Physical Technology Engineer Alcatel Canada, Inc. (613) 784-4793 (888) 662-3425 x 4793 --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------