I like the idea of the small corner chamfer, I haven't heard about that.
What dimensions do you use?
Do you ever get charged more for extra routing complexity?
On Tue, Feb 26, 2013 at 11:11 AM, Brooks, William <
[log in to unmask]> wrote:
> Thanks, Dieter. :) Hope you are doing okay, long time since I have talked
> with you.
>
> I have been pretty busy and have not posted in some time... here are a
> couple of thoughts for the questioner...
> Usually I use 20 to 25 mils for copper to the board edge... this works for
> most standard board designs that I encounter.
> It allows the bare board fabricator to bond the edges of the laminate
> well, leaving some tolerance for trimming, and usually we chamfer the
> corners of the boards to avoid accidental injury by the folks that assemble
> and handle them... 90 degree board corners can be pretty sharp... Typically
> a non plated thru hole will be a tooling hole or mounting hole... though
> sometimes it is necessary to break out the hole into a slot on the edge of
> the board to get the screw into the mounting area... of course there is
> board edge castellation that leaves a half diameter plated thru hole
> scalloped along the edge of the board interconnecting the edge of the board
> from top to bottom... and mouse/rat bite holes that allow excising boards
> from assembly panels. The spec is very thorough but it should not tie the
> hands of the designer... it really is intended to help standardize and save
> money and effort for all parties involved... which it does admirably! :)
>
>
> Best regards,
>
>
> William Brooks, CID+
> Senior MTS (Contract)
> 2747 Loker Ave West
> Carlsbad, CA 92010-6603
> 760-930-7212
> Fax: 760.918.8332
> Mobile: 760.216.0170
> E-mail: [log in to unmask]
>
>
>
> -----Original Message-----
> From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of
> Dieter Bergman
> Sent: Tuesday, February 26, 2013 7:50 AM
> To: [log in to unmask]
> Subject: Re: [DC] Edge spacing
>
> Hi Gary,
>
> The present IPC-2222A states the following:
>
> 10.1.1 Edge Spacing Except for edge printed board contacts, the minimum
> distance between conductive surfaces and the edge of the finished printed
> board, or a NPTH, shall not be less than the minimum spacing specified in
> Table 6-1 of IPC-2221 plus
> 0.4 mm [0.0157]. Printed boards that slide into guides shall have a
> minimum external conductor to guide distance of 1.25 mm
> [0.0492 in] or minimum electrical clearance (see Table 6-1 of IPC-2221),
> whichever is greater. Special design applications in areas such as high
> voltage, surface mount, and radio frequency (RF) technology may require
> variances to these requirements.
> Ground and heat sink planes may extend to the edge when required by design.
> The design should provide sufficient edge spacing to avoid unnecessary
> haloing and crazing rejections. Rejections can occur when the edge defect
> is greater than 50% of the clearance to edge spacing. Brittle material or
> heavier glass weights increase this risk.
>
> The fabricator can do this, but from a design point of view we worry about
> edge defects the can impact the assembly performance.
>
> Dieter
>
> -----Original Message-----
> From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Gary
> Koven
> Sent: Tuesday, February 26, 2013 9:10 AM
> To: DesignerCouncil
> Subject: [DC] Edge spacing
>
> We design small form factor PCBs with board edge to copper spacing
> typically 0.25mm (0.010").
>
> Thus far, no fabricator, whether our American prototype or our Asia
> Pacific production, has indicated this distance is a problem. Online
> prototype shops such as Advanced Circuits specify this distance as their
> minimum.
>
>
> Which IPC document addresses minimum edge spacing? My copy of IPC-2222 is
> 15 years old,and I was not able to find this information in any other IPC
> specs on hand.
>
>
>
> TIA and Best Regards,
>
> Gary M. Koven, C.I.D.
> InVue Security Products
>
> Charlotte, NC, USA
> Board Of Directors, RTP Chapter
>
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