Lou, I also agree with Roger and Lisa. Ink should not be allowed on surface mount pads. For thru-hole pads, however, it depends on the classification of your design. For CLASS 1 and 2 designs it is acceptable as long as the ink does not get into the hole. For CLASS 3 designs it is not allowed. Reference IPC-A-600D section 12.2 and 12.3 Lou Takach Union Switch & Signal Inc. 412.688.2574 [log in to unmask] ------------- Original Text From: Lisa Williams <[log in to unmask]>, on 5/28/96 2:52 PM: Received: by RnD.SWITCH.COM; Tue, 28 May 96 14:52:42 EDT Received: from simon.ipc.org (IPC.ORG [168.113.24.64]) by proxy2.switch.com (8.6.12/8.6.9) with ESMTP id OAA28404; Tue, 28 May 1996 14:48:10 -0400 Received: from ipc.org by simon.ipc.org via SMTP (940816.SGI.8.6.9/940406.SGI) id NAA17261; Tue, 28 May 1996 13:43:22 -0700 Resent-Date: Tue, 28 May 1996 13:43:22 -0700 Received: by ipc.org (Smail3.1.28.1 #2) id m0uORJo-0000FtC; Tue, 28 May 96 11:08 CDT Resent-Sender: [log in to unmask] Old-Return-Path: <willli> Date: Tue, 28 May 1996 11:08:18 -0500 (CDT) From: Lisa Williams <[log in to unmask]> Subject: Re: FAB: Silk-screen ink on surface mount pads (fwd) To: [log in to unmask] Message-ID: <Pine.3.89.9605281151.B37745-0100000@ipc> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Resent-Message-ID: <"awTeD2.0.PAC.sJogn"@ipc> Resent-From: [log in to unmask] X-Mailing-List: <[log in to unmask]> archive/latest/1744 X-Loop: [log in to unmask] Precedence: list Resent-Sender: [log in to unmask] ---------- Forwarded message ---------- Date: Tue, 28 May 1996 08:43:24 -0700 From: Bilal Khalaf -Applications <[log in to unmask]> To: [log in to unmask] Subject: Re: FAB: Silk-screen ink on surface mount pads Lou, I agree with Roger. Silkscreen on pads should be addressed at design stages and should not be allowed on pads. Most of the Gerber editors have the capability to clear the silkscreen from any pads and hopefully, your designers/contractors are aware of that capability and know they should not have silkscreens on pads: SM or thruhole. bilal > Lou, > > We have never allowed silkscreen ink on the pads. We have had our > vendors put the silkscreen on the pads before due to misregistration > or errors in their fab artwork. We have seen solderability problems > due to this kind of defect. If it's not in an industry spec., then it > would have to be a requirement in your company's specs. or your > individual specs. PC boards should be DESIGNED such that there is no > silkscreen on the pads. > > Regards, > > Roger Held > Hitachi Computer Products (America), Inc. > > >______________________________ Reply Separator >_________________________________ >Subject: FAB: Silk-screen ink on surface mount pads >Author: [log in to unmask] at Internet-HICAM-OK >Date: 5/28/96 8:42 AM > > >Recently I have seen PC boards with silk screen ink on surface mount >pads. Is any of this allowed? Looking at the PC board IPC standards, I >don't see this subject addressed. May I have some guidance? >Lou Hart 412-858-6117 > > >. >