Well...I have seen post separation on boards with 0.0003" etchback, so I think your PWB supplier is off base. Post separation has many causes that cannot be solved with providing a three sided lock (which is my guess as to why they recommended etchback). Your supplier has a post separation problem and will not acknowledge it. They are being unresponsive. I know what I do with suppliers like this. If you want to call out etchback, remember it is more expensive. There are plenty of suppliers out there who desmear and have NO post separation. Regards, Dave Sullivan Rockwell Collins, Inc. [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: Etchback Author: [log in to unmask] at ccmgw1 Date: 4/8/97 7:44 PM The purpose of this request is to solicited some opinions as to the merits of etchback. My company has recently had some field returns which analysis has disclosed that the failures are a result of post separation. The PWB supplier ,when contacted, suggested that if our drawing had required etchback there would have been a less of a chance for a failure of this nature to occur. My company uses both IPC-RB-276 (IPC-6011&IPC-6012) and MIL-STD-55110E as procurement specifications and it so happens we have experienced failures in PWB's procured using both specifications. The guidance furnished by either is not definitive just if the Master Drawing say do it the etchback has to fall within certain limits. We have always gone with only a chemical desmear (permanganate) with no apparent epoxy removal. We have never specified a chemical etchback for fear of latent defects from residual chemicals. Our PWB supplier tells us there is now available plasma etchback/chemical desmear (permanganate) which we are told eliminates the potential for the latent defect problem. Does anyone have data which would provide information as to which process would make the more reliable product. Any and all replies and opinions welcome. *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * 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] * *************************************************************************** Received: from by ccmgw1.cacd.rockwell.com (SMTPLINK V2.11) ; Tue, 08 Apr 97 19:44:39 cst Return-Path: <[log in to unmask]> Received: from stealth.cacd.rockwell.com (stealth) by mailserv with ESMTP (1.40.112.8/16.2) id AA054136184; Tue, 8 Apr 1997 19:36:24 -0500 Received: by stealth.cacd.rockwell.com; id TAA20555; Tue, 8 Apr 1997 19:34:09 -0500 Received: from unknown(168.113.24.64) by stealth.cacd.rockwell.com via smap (3.2) id xma020551; Tue, 8 Apr 97 19:34:07 -0500 Received: from ipc.org by simon.ipc.org via SMTP (940816.SGI.8.6.9/940406.SGI) id TAA16647; Tue, 8 Apr 1997 19:23:10 -0700 Resent-Date: Tue, 8 Apr 1997 19:23:10 -0700 Received: by ipc.org (Smail3.1.28.1 #2) id m0wEjaQ-000BjkC; Tue, 8 Apr 97 17:41 CDT Resent-Sender: [log in to unmask] Old-Return-Path: <[log in to unmask]> From: [log in to unmask] (BOB HAYNES) To: [log in to unmask] Subject: Etchback Date: Tue, 08 Apr 97 17:15:20 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii Content-Description: Message Body Content-Transfer-Encoding: 7BIT Message-Id: <[log in to unmask]> Resent-Message-Id: <"JXOoc.0.99C.mciIp"@ipc> Resent-From: [log in to unmask] X-Mailing-List: <[log in to unmask]> archive/latest/11789 X-Loop: [log in to unmask] Precedence: list Resent-Sender: [log in to unmask] *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * 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] * ***************************************************************************