======== Original Message ======== Sender: [log in to unmask] Received: from simon.ipc.org (IPC.ORG [168.113.24.64]) by hil-img-4.compuserve.com (8.6.10/5.950515) id IAA21524; Thu, 12 Sep 1996 08:39:46 -0400 Received: from ipc.org by simon.ipc.org via SMTP (940816.SGI.8.6.9/940406.SGI) id HAA25462; Thu, 12 Sep 1996 07:35:11 -0700 Resent-Date: Thu, 12 Sep 1996 07:35:11 -0700 Received: by ipc.org (Smail3.1.28.1 #2) id m0v1AuW-0000PoC; Thu, 12 Sep 96 07:30 CDT Resent-Sender: [log in to unmask] Old-Return-Path: <[log in to unmask]> Message-ID: <[log in to unmask]> Date: Thu, 12 Sep 1996 22:37:47 +1100 From: Andy Kowalewski <[log in to unmask]> Organization: PC-CAD Pty Ltd X-Mailer: Mozilla 2.02Gold (Win95; I) MIME-Version: 1.0 To: [log in to unmask] Subject: Controlled depth drilling Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Resent-Message-ID: <"xKVNI2.0.j6I.U90Eo"@ipc> Resent-From: [log in to unmask] X-Mailing-List: <[log in to unmask]> archive/latest/6176 X-Loop: [log in to unmask] Precedence: list Resent-Sender: [log in to unmask] Hi, I'n in the end run of a revision to a board design which is double sided eight layers with blind vias on layers 1/2, 1/4, 5/8 and 7/8, as well as the normal through-hole 1/8 vias. Sizes are 0.3mm (12mil) for in-pad blind vias and 0.6mm (24mil) wherever I can get away with it. We've already had batches of Rev A boards made up with sequential lamination and with controlled depth drilling and we're in the process of evaluating suppliers and their boards. My problem is that we are having trouble nailing down any sort of specification for our next run. These will also be prototypes but we're getting close to volume production and need something for QA to hang its hat on for incoming inspection. Factors we are considering are: a) Boards manufactured with controlled depth drilling promise to be considerably less expensive (30% on one estimate) b) The repeatability of the depth of drilling is an unknown, from stack to stack and from batch to batch. c) The long term reliability of a blind via defined this way is unknown to us d) The aspect ratio of a blind hole appears to be critical, but what is optimum and what is acceptable? and so on and on. Can anyone help? Thanks in advance *************************************************************************** * 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 ======== I am also very interested in knowing what manufacturers are supplying blind vias using a controlled depth drilling process. What volumes are being produced and what type of process is used for the hole metalization. What do the cross sections of the blind via holes look like ? Are the drill tools standard ? Aspect ratios ? I would appreciate talking with any suppliers of printed circuit boards who might have this information first-hand. Tony King Elexsys International Inc. Nashua N.H. 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. * ***************************************************************************