Mail*Link(r) SMTP FWD>FAB: Edge Plating Ted -- You're right, I don't know of any and we couldn't find any requirements for "edge plating" of the periphery of printed boards or cut-outs in printed boards out there either. >Date: 5/16/96 10:50 AM >From: Edwards, Ted A (AZ75) >[log in to unmask] >We procure microwave boards that to IPC-HF-318 would be Class 3 Type 3. >Recently we see some suppliers having problems which result in plating >voids. The criteria for voids in a plated through hole are defined but >voids in the plated edges of the board do not seem to be defined anywhere. So what we did was to include the requirements in notes on the product definiton (master) drawing. We specify the plating thickness shall meet the plated-through hole thickness requirements. Depending on the design requirements, we allow edge-plated voids to be a percentage of printed board thickness, or more generally, one board thickness in size (length and width). At first we specified an adhesion requirement using the ol' tape peel test, it worked for epoxy and polyimide base materials, but not for thicker PTFE base materials. Blisters / unbonded areas are not allowed for Class 3 because it is unknown if the separated area will propagate due to volatile materials in the base material or separation. For Class 2, the edge blister / separation can be up to two base material thicknesses long for most operating environments. Most of the requirements are based on the responsible design engineer's (not the printed board designer or manufacturing) assessment (based on testing / knowledge / experience) for that particular (or similar) design. > Question 1. A void across an interconnect in a normal multilayer is > real bad but what about a void across the same interconnect > when it is a ground that goes all the way around the periphery > of the finished board? A "peripheral void", or even a small percentage of the periphery of the perimeter of the printed board or a cutout is a no-no. Care must be exercised to ensure the "peripheral-like" voids are a small percentage of the wavelength of the highest frequency of concern (that's why we decided to limit voids to generally one board thickness). Voids should not be allowed to occur in a linear pattern of approximately uniform pitch. The concern is the 0.5 wavelength effects of the spaces (voids) between ground connections at the highest operating frequency. > Question 2. Does anybody know where plated edge requirements are > listed? Nope, we adapted tradition plated-through hole requirements as mentioned above. > Question 3. Since I can not find what I am looking for in a > specification, if no specification exists, does anybody have > > criteria? Included above. Hope this helps, Ralph Hersey e-mail: [log in to unmask] ------------------ RFC822 Header Follows ------------------ Received: by quickmail.llnl.gov with SMTP;16 May 1996 10:49:53 -0700 Received: from ipc.org by simon.ipc.org via SMTP (940816.SGI.8.6.9/940406.SGI) id MAA13315; Thu, 16 May 1996 12:41:01 -0700 Resent-Date: Thu, 16 May 1996 12:41:01 -0700 Received: by ipc.org (Smail3.1.28.1 #2) id m0uK6PI-0000CjC; Thu, 16 May 96 12:00 CDT Resent-Sender: [log in to unmask] Old-Return-Path: <[log in to unmask]> X400-Received: by /c=US/admd=MCI/prmd=Honeywell/; converted ( IA5-Text); Relayed; 16 May 1996 12:05:11 -0500 X400-Received: by mta HW-MTA-AZ in /c=US/admd=MCI/prmd=Honeywell/; converted ( IA5-Text); Relayed; 16 May 1996 12:05:11 -0500 X400-MTS-Identifier: [/c=US/admd=MCI/prmd=Honeywell/; 00ED1319B6047F5A-HW-MTA-AZ] Content-Identifier: 00ED1319B6047F5A Content-Return: Allowed X400-Content-Type: P2-1988 ( 22 ) Conversion: Allowed Original-Encoded-Information-Types: IA5-Text Priority: normal Disclose-Recipients: Prohibited Alternate-Recipient: Allowed X400-Originator: [log in to unmask] X400-Recipients: non-disclosure; Message-Id: <00ED1319B6047F5A*/c=US/admd=MCI/prmd=Honeywell/o=AZ-MTA/ou=MSMail/ou=CAS/s=Edwards/g=Ted/i=A/@MHS> Date: 16 May 1996 12:05:11 -0500 From: "Edwards, Ted A (AZ75)" <[log in to unmask]> To: "[log in to unmask]" <[log in to unmask]> (Return requested) Subject: FAB: Edge Plating MIME-Version: 1.0 Resent-Message-ID: <"O5Ope2.0.OjD.Eyrcn"@ipc> Resent-From: [log in to unmask] X-Mailing-List: <[log in to unmask]> archive/latest/4179 X-Loop: [log in to unmask] Precedence: list Resent-Sender: [log in to unmask]