What I have failed to mention is the process must be UL recognized. That means not only the raw material, in this case soldermask, but the process used to apply must be UL recognized. In addition UL must also recognize the use of soldermask as a dielectric insulating material. If anyone knows of conformance of soldermask to those requirements, let me know. ______________________________ Reply Separator _________________________________ Subject: INSULATING LAYER Author: [log in to unmask] at Internet Date: 11/1/96 2:53 PM We have an application on a 2 layer board with through hole technology which requires an insulating material laminated/applied to one surface/side. Initially we thought of having a prepreg material laminated to one surface but are unsure if this is the most cost effective method. Anyone out there who knows of a method or material which would support this requirement please respond. Some of our requirements are; >>>>>>Have you considered solder mask!!!! 1. Must be a UL recognized material >>>>>>>>yes 2. Must provide at least 500V of dielectric insulation >>>>>>>>>solder mask is typically 40V per micron, so to provide 500V requires a minimum of 12.5um of resist, easily achievable by double coating wet on dry. 3. Would preferably be thin, .001-.003 thick. >>>>>>>>>see above Some questions we have are; 1. What type of relief would be needed around PTH? >>>>>>>>photoimageable = print tolerance 2. How thick would the material nee d to be? >>>>>>>>see above 3. Who is doing this type of fabrication today? >>>>>>>>everyone 4. Can it be applied selectively? >>>>>>>>photoimage 5. What is the typical cost impact to a double sided boar d? >>>>>>>>do you want % or in cents - or do you already have the the answer and its on your board already? Dougal Stewart Exacta Circuits Scotland ************************************************************************ *** * 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. * *************************************************************************** ---- End of mail text Additional SMTP headers from original mail item follow: Received: from simon.ipc.org by ibmmail.COM (IBM VM SMTP V2R3) with TCP; Fri, 01 Nov 96 08:55:07 EST Received: from ipc.org by simon.ipc.org via SMTP (940816.SGI.8.6.9/940406.SGI) id HAA20522; Fri, 1 Nov 1996 07:42:54 -0800 Resent-Date: Fri, 1 Nov 1996 07:42:54 -0800 Received: by ipc.org (Smail3.1.28.1 #2) id m0vJJ5U-0000UlC; Fri, 1 Nov 96 06:52 CST Resent-Sender: [log in to unmask] Old-Return-Path: <[log in to unmask]> Mime-Version: 1.0 Message-Id: <[log in to unmask]> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Content-Description: cc:Mail note part Resent-Message-ID: <"5IM_7.0.lrE.DAVUo"@ipc> Resent-From: [log in to unmask] X-Mailing-List: <[log in to unmask]> archive/latest/7307 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 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. * ***************************************************************************