Hi TechNet! Shaun - there are people in the electronics industry that do use Sn/Pb plated parts in gold sockets so don't think that it is never done. But those folks have taken into consideration the issues that Dr. Lei brought up - e.g. they seal the PWA so that water can't get to the connection or they use very high insertion forces plus make design considerations such that the micro-motions that occur don't impact the electrical functionality. Most people follow Dr. Lei's suggestion and avoid the gold-Sn/Pb issue altogether. IPC-GH-850 "Handbook of Interconnect Contact Finishes" has some good general info on gold-Sn/Pb that may be helpful. Hey IPC - What happened to IPC-GH-850? I do not see it listed in the IPC catalog! Is it still procurable? Dave Hillman Rockwell Collins [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: Re: Gold Migration into Tin/Lead Author: [log in to unmask] at ccmgw1 Date: 12/2/96 4:26 PM Shaun I suggest that you do not use tin/lead plated part with gold socket. The contact interface will become unstable and contact integrity will be compromised. The circuit will experience intermittent and/or open after a while, depending on the operating condition. Tin/lead WILL form oxide and cause contact resistance to increase to the undesirable level. This effect will be greatly accelerated by contacting gold due to the galvanic effect. In fact, any dissimilar metal contact is not recommended. Furthermore, micro-motions between the contact interface will probably move (smear) gold and tin/lead around, which does not help in this situation. Kuan-Shaur Lei, Ph.D. Senior Member of Technical Staff Advanced Technology Department Compaq Computer Corporation (281) 518-8099 (phone) e-mail: [log in to unmask] Date: Mon, 2 Dec 1996 08:29:54 -0600 From: [log in to unmask] (SDalton) To: [log in to unmask] Subject: Gold migration into tin/lead Message-ID: <[log in to unmask]> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Content-Description: cc:Mail note part Has anyone heard of problems with seating a tin/lead leaded part into a gold socket? I have heard concerns that the gold will migrate into the tin/lead even though it is only a mechanical connection. I would appreciate any input you can give me on this issue. Thanks, Shaun Dalton [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. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************