---- Begin Forwarded Message via SMTP (940816.SGI.8.6.9/940406.SGI) id NAA16400; Wed, 4 Dec 1996 13:31:20 -0800 Resent-Date: Wed, 4 Dec 1996 13:31:20 -0800 Received: by ipc.org (Smail3.1.28.1 #2) id m0vVMjc-0000UsC; Wed, 4 Dec 96 13:11 CST Resent-Sender: [log in to unmask] Old-Return-Path: <[log in to unmask]> From: [log in to unmask] Date: Wed, 4 Dec 96 13:14:10 EST Message-Id: <[log in to unmask]> X-Priority: 3 (Normal) To: <[log in to unmask]> Subject: Tented vias??? Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Resent-Message-ID: <"OP7Wc3.0.BqC.rpSfo"@ipc> Resent-From: [log in to unmask] X-Mailing-List: <[log in to unmask]> archive/latest/8238 X-Loop: [log in to unmask] Precedence: list Resent-Sender: [log in to unmask] Status: RO Colleagues: Our in house SMT assembly facility has asked that we tent our vias on top and bottom sides to aid in solder bridge reduction. If bottom tenting is not possible becaues vias may double as test points, they ask that we still tent the top (component) side. They use a no clean process. I am concerned that contaminants will be trapped in vias tented only on one side and cause premature failure down the road. Normal via size is .012. What are your thoughts on tented vias??? One side? Both sides? Not tented ever? Why??? What other problems may we encounter? Thanks in advance for your opinions. gary ... Gary, I was involved in a research project involving the long term effects of no-clean fluxes with Dr. Carl Tautscher and we had discovered that there were measurable amounts of eliphatic acid (sp?) found in the remaining distillate of the autoclave used in the accelerated life test. Although the test specimines had not exhibited severe effects, the presence of the substance caused some concern, as the typical test methods used in such proceedures actually volitalize the acid and distribute it in the surrounding atmosphere. If these things are true, then entrapment within the spaces you describe could cause concern. Carl is by far more qualified than I to discuss this with you, and he is an Independent Engineering Consultant: Carl J. Tautscher P.O. Box 204 Lynnwood, Wa. 98012 Ph: (206) 776-5190 Fx: (206) 776-2274 Regards, Edward J. Popielarski QTA Machine (714) 364-6614 [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. * ************************************************************************ *** * 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] * ************************************************************************ *** *************************************************************************** * 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] * ***************************************************************************