Hold on Joyce, you changed the subject. Larry was talking about the INTERNAL pads in his original posting.
Just to clarify, I see no reason why surface layer pads cannot remain, albeit electrically redundant, for the purpose of distribution of stresses and increased robustness.
They usually do not cause any issues.
Internal vias connected to unused pads do not crack if they are not there to begin with!
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Yuan-chia Joyce Koo
Sent: Tuesday, February 27, 2018 11:46 AM
To: [log in to unmask]
Subject: Re: [TN] Non Functioning pads
http://www.dfrsolutions.com/hubfs/DfR_Solutions_Website/Resources-
Archived/White-Papers/Reliability/Non-Functional-Pads-Should-they-
Stay-or-Should-they-Go.pdf
On Feb 27, 2018, at 12:36 PM, Decker, Scott UTAS wrote:
> I agree with Richard. I was a firm believer in keeping them to protect
> the via barrels from cracking, so no way was I going to do it. Then
> there was a study done many years ago, (I don't remember who did it)
> that showed that only for very thick boards, like .120"
> or more, was there any benefit to leaving them in. That benefit was
> very small and it was not as much as you get from the Fabricator and
> such, for the extra space you got... That said, we pull them on all of
> our boards and we do class 3's all the time. One additional thing I
> just thought of. In the past I used a lot, (ok almost exclusively
> polyimide boards) and I believe that was where the benefit was a good
> one, but I don't remember now for sure since we don't use Polyimide
> here. :-]
>
>
> Scott Decker - Staff Engineer, PCB Design Services CID+ - Electronic
> Systems Center UTC AEROSPACE SYSTEMS
> 3445 S. 5th Street, Suite 170, Phoenix, AZ 85040 U.S.A.
> Tel: 602 308 5957 FAX: 602 243 2347
> KE7MWT AKA:PadMasterson
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>
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> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D
> Sent: Tuesday, February 27, 2018 10:19 AM
> To: [log in to unmask]
> Subject: [External] Re: [TN] Non Functioning pads
>
> I don't see why not, unless they are used for capacitance or antennae.
> If they are NOT used for those purposes, then they should be removed
> for the same reason.
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Larry
> Sent: Tuesday, February 27, 2018 11:12 AM
> To: [log in to unmask]
> Subject: [TN] Non Functioning pads
>
> Is there any reason I cannot remove non functioning pads on the inner
> layers for an Class 3 PCB?
>
> Many thanks,
>
> Larry
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