======== Original Message ======== Sender: [log in to unmask] Received: from simon.ipc.org (IPC.ORG [168.113.24.64]) by dub-img-6.compuserve.com (8.6.10/5.950515) id VAA08080; Thu, 1 Aug 1996 21:01:58 -0400 Received: from ipc.org by simon.ipc.org via SMTP (940816.SGI.8.6.9/940406.SGI) id TAA18156; Thu, 1 Aug 1996 19:58:33 -0700 Resent-Date: Thu, 1 Aug 1996 19:58:33 -0700 Received: by ipc.org (Smail3.1.28.1 #2) id m0um8U0-0000KoC; Thu, 1 Aug 96 19:52 CDT Resent-Sender: [log in to unmask] Old-Return-Path: <[log in to unmask]> Date: Fri, 02 Aug 1996 09:01:45 +0900 Message-ID: <[log in to unmask]> X-Sender: [log in to unmask] (Unverified) X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: [log in to unmask] From: chen xiao bo <[log in to unmask]> Subject: PCMCIA Dimensional Stabilty Resent-Message-ID: <"qVTpF3.0.wfL.Y5L0o"@ipc> Resent-From: [log in to unmask] X-Mailing-List: <[log in to unmask]> archive/latest/5519 X-Loop: [log in to unmask] Precedence: list Resent-Sender: [log in to unmask] Has anyone had any experience in controlling ultrathins (0.004 in 0.5/0.5) dimensional stabibity? What are the factors that effect the ultrathins misregistration and how to reduce the misregistration to the minmum. Appreciate if anyone can provide an answer. Thanks in advance Chen Xiao bo *************************************************************************** * 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. * *************************************************************************** ======== Fwd by: Tony King / N ======== Chen, Thin core can be difficult to control, but there are several things that will improve registration: 1. Be sure that copper is solid around the tooling holes. This is important for all core thicknesses, but critical for thin core. 2. Thin core material does not always lay flat at post etch punch (I assume your process includes this operation) Signal over signal thin core is especially sensitive to this, it tends to sag if not supported completely. 3. Proper venting is important, leave as much copper on the inner layer borders as possible yet providing good venting. 4. Be very careful at layup of the cores, do not damage the tooling holes when placing cores over the pins. Cross section the outer layer tooling holes if misregistration is noticed at drill. To build good boards you must first build good tooling holes. 5. It goes without saying that scale factors at CAM must be optimized for thin core movement. NOTE: Some people will say that scrub prior to image of cores is critical and will cause distortion. If this is true, I have not found it significant. I think the above 5 issues represent at least 90% of the causes for misregistration, scrub may be a small portion of the last 10% but should be the last place to look... Tony King Elexsys International Inc. Nashua N.H. Phone: 603-886-0066 [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. * ***************************************************************************