James/Tom,

I'll probably leave it for now but as designs get more dense we are always looking for ways to increase the routeability  (not sure if that is a word) of a design.

Thanks,

Larry

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Tom Brendlinger
Sent: Wednesday, February 28, 2018 12:41 PM
To: [log in to unmask]
Subject: Re: [TN] -|EXT|- Re: [TN] Non Functioning pads

I have a point of clarification on what James just said.

I fully agree that if your design spacing is driven by drill accuracy or the IPC design standards, then you should not remove NFP.

However, if your design spacing is based on conductive anodic filament formation, then removing NFP does get you somewhere, as CAF is a substantially larger problem in the same layer as it forms along the weave of the reinforcement.

T

On Wed, Feb 28, 2018 at 3:32 AM, HEAD James <[log in to unmask]> wrote:

> I just re-read my e-mail and realised it could be miss-interpreted. 
> What I meant to say is PCB Fabricators can remove non-functional pads 
> to improve the PCB Fabrication process. PCB Designers should not 
> remove non-functional pads just to be able to route tracks tighter to holes.
>
> The PCB CAD package I use, Pulsonix, can automatically remove 
> non-functional pads if the user selects this option but it has a 
> additional DRC check option that can be turned on or off, that keeps 
> the DRC pad to track spacing as though the non-functional pad were still present.
>
> This is based upon feedback I received from several PCB Fabricators 
> that I have used.
>
> Regards,
>
> James
>
> James Head
> Oxford Instruments
> Magnetic Resonance
> www.oxford-instruments.com
> www.twitter.com/oxinst : @oxinst
> www.facebook.com/oxinst
> www.linkedin.com/company/oxford-instruments
>
> Tubney Woods, Abingdon, Oxon OX13 5QX, UK
> Tel: +44 (0) 1865 393200
> Email: [log in to unmask]
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of HEAD James
> Sent: 28 February 2018 08:19
> To: [log in to unmask]
> Subject: Re: [TN] -|EXT|- Re: [TN] Non Functioning pads
>
> I would say no, don't remove them in this case. PCB Fabricators remove 
> non-functional pads to reduce drill wear and tear and improve the side 
> profile of the drill. They still need you to maintain the same 
> clearance between hole wall and track as though the non-functional pad 
> was still there. Non-functional pads should only be removed to improve 
> PCB fabrication and never to be able to route tracks closer to a hole.
>
> Regards,
> James
>
> James Head
> Oxford Instruments
> Magnetic Resonance
> www.oxford-instruments.com
> www.twitter.com/oxinst : @oxinst
> www.facebook.com/oxinst
> www.linkedin.com/company/oxford-instruments
>
> Tubney Woods, Abingdon, Oxon OX13 5QX, UK
> Tel: +44 (0) 1865 393200
> Email: [log in to unmask]
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Larry
> Sent: 27 February 2018 17:28
> To: [log in to unmask]
> Subject: -|EXT|- Re: [TN] Non Functioning pads
>
> Ok the customer's main concern is that the board is still Class 3 if 
> the non functioning pads are removed, I can't find anything in the IPC 
> specs that says I can't remove them.  The main reason is to free up 
> space for routing on the inner layers.
>
> Thanks all,
>
> Larry
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