You're going to need to spec a nickel underlayer (barrier and soldered to) and a max gold thickness to prevent voiding and gold embrittlement of solder joints. We spec that the nickel be an electroless nickel/immersion gold process be used and that the nickel thickness is a minimum of 100 microinches followed by 3 - 8 microinches of 99.9% gold. The gold is also soft, <90 Knoop, and can be wire bonded to. This gold finish is a Type III Hardness Grade A strike according to MIL-G-45204. The immersion gold process is electroless but self limiting, nickel is displaced and replaced by gold. As soon as the surface layer of nickel is no longer exposed, the plating process comes to a halt. Depending on who/what PCB shop or chemical supplier you talk to, the resultant gold thickness is in the 2 - 12 microinch range. Tracy Tennant [log in to unmask] ---------- Start of forwarded message ---------- Message# 802373 24-APR-1996 06:42:42.00 From: [log in to unmask] To: STHUMMEL,TTENNANT,[log in to unmask] Subj: Re: Gold Flash on PWB's Received: from micron.co by BOGEN4 Wed, 24 APR 96 06:42:13 MDT Received: from is04.micron.com by micron.com (SMI-8.6/SMI-SVR4) id GAA01635; Wed, 24 Apr 1996 06:41:51 -0600 Received: from simon.ipc.org ([168.113.24.64]) by relay.micron.com with SMTP id <185386>; Wed, 24 Apr 1996 06:42:11 -0600 Received: from ipc.org by simon.ipc.org via SMTP (940816.SGI.8.6.9/940406.SGI) id HAA28011; Wed, 24 Apr 1996 07:40:35 -0700 Resent-Date: Wed, 24 Apr 1996 08:40:35 -0600 Received: by ipc.org (Smail3.1.28.1 #2) id m0uC3AT-00007KC; Wed, 24 Apr 96 06:55 CDT Resent-Sender: [log in to unmask] Old-Return-Path: <[log in to unmask]> From: [log in to unmask] Date: Wed, 24 Apr 1996 08:01:25 -0600 Encoding: 38 Text Message-Id: <[log in to unmask]> To: [log in to unmask] Resent-To: <[log in to unmask]> Resent-To: <[log in to unmask]> Resent-To: <[log in to unmask]> Subject: Re: Gold Flash on PWB's Resent-Message-ID: <"LqCG41.0.HA9.mQXVn"@ipc> Resent-From: [log in to unmask] X-Mailing-List: <[log in to unmask]> archive/latest/3607 X-Loop: [log in to unmask] Precedence: list Resent-Sender: [log in to unmask] STEPHEN, IPC-D-275 SECT 3.8.4.3 (SOUNDS LIKE A STAR DATE DOESN'T?), CONTAINS INFORMATION ON GOLD PLATING. ALSO REFERENCE SECTION 3.8.4.4 ON NICKEL UNDERPLATING. TABLES 3-8 AND 3-9 WILL GIVE YOU AN IDEA OF WHAT YOU NEED FOR YOU'RE END PRODUCT. AS TO WETHER IT'S WORTH IT, YOU MUST CONSIDER YOUR END USAGE AND THEN TALK WITH YOU'RE FAB HOUSE. REGARDS, ROB BUTTERWORTH SR PWB DESIGNER ADC VIDEO SYSTEMS 999 RESEARCH PARKWAY MERIDEN, CT 06450 [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: Gold Flash on PWB's Author: [log in to unmask] at internet-mail Date: 4/24/96 2:52 AM Can anyone supply a specification to call up when requesting a Gold Flash finish on a PWB and is it worth it today, with the advances with the HASL finishes. Regards Stephen Cooper Manufacturing Projects Manager SCITEC LIMITED Apollo Place Lane Cove NSW 2066 Australia PH : +612 428 9500 Fax : +612 428 9589 Email : [log in to unmask]