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April 1997

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From:
"James Patterson"<[log in to unmask]>
Date:
Fri, 11 Apr 97 13:32:59 -0500
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Received: from simon.ipc.org by mail.foster-miller.com (ccMail Link to SMTP R6.00.01) ; Fri, 11 Apr 97 10:12:40 -0500 Return-Path: <[log in to unmask]> Received: from ipc.org by simon.ipc.org via SMTP (940816.SGI.8.6.9/940406.SGI) id IAA00999; Fri, 11 Apr 1997 08:57:57 -0700 Resent-Date: Fri, 11 Apr 1997 08:57:57 -0700 Received: by ipc.org (Smail3.1.28.1 #2) id m0wFgQR-000Bj9C; Fri, 11 Apr 97 08:31 CDT Resent-Sender: [log in to unmask] Old-Return-Path: <[log in to unmask]> From: [log in to unmask] Date: Fri, 11 Apr 1997 09:41:12 -0400 (EDT) Message-ID: <[log in to unmask]> To: [log in to unmask] Subject: Re: DES: HTE Copper Resent-Message-ID: <"eA4mo.0.vHV.fqZJp"@ipc> Resent-From: [log in to unmask] X-Mailing-List: <[log in to unmask]> archive/latest/11893 X-Loop: [log in to unmask] Precedence: list Resent-Sender: [log in to unmask] Hi Randy, On the HTE (E3) vs. the Standard (E1) copper foil, the issues are not as clean-cut as one would like. FIRST, because the minimum property values in IPC-MF-150 are so low, there is from a spec point little difference with the exception of elevated temperature behavior. SECOND, because the copper foil vendors stonewalled the users' efforts, the ED foils do not have a ductility requirement, only a minimum elongation which for foils is a lousy ductility indicator (spec minimums of 2 and 3%). As a consequence the foils from the different vendors differ significantly (see IPC-TR-484, Results of IPC Copper Foil Ductility Round Robin Study), where in some cases the E1 foil from one vendor was better than the E3 foil from another. THIRD, these commercial foils are plated at very high plating current densities requiring lots of exotic additives; these plating solutions are rather precariously balanced. These solutions do however occasionally go off-balance, resulting in large distributions of properties such as strength, ductility, electrical resistivity, etchability, density, etc., all however within MF-150, because these same vendors kept the spec numbers down. The means of these distributions are significantly above the minimum spec values, however. Thus, the only foils that will hurt a customer are the tail ends of the distributions coming close to the minimum spec values. When these plating solutions go off-balance, apparently more of the additives (mostly organics) are co-deposited at the copper grain boundaries. The result is reduced strength and ductility and increased electrical resistivity and etch rates. The difference between E1 and E3 is that the distribution apparently is moved to a higher level. I say 'apparently', because no hard data exist except at the foil manufacturers. Further, no hard data exist as to the improvements obtained with a switch from E1 to E3 (there are strength, ductility and fatigue data in IPC-TR-484); the available information is all anecdotal, but positive except perhaps for drilling. I would also suspect, that there are large differences between copper foils from different vendors. Werner Engelmaier Engelmaier Associates, Inc. Electronic Packaging, Interconnection and Reliability Consulting 23 Gunther Street Mendham, NJ 07945 USA Phone & Fax: 201-543-2747 E-mail: [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] * ***************************************************************************

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