one of my post got rejected.  i would be careful to remove the non- 
functional pads for two reasons: (1) modification of PWB is consider  
as major change based on my book (old), required for requal (It  
should).  (2) non-functional pads removal may impact thermal and/or  
balance of board, for class 3, I would be careful.  assume it is  
mission critical or not easy to re-pair and overhaul (can't hot swap  
it easily).
my 1.5 cents.
jk
On Feb 27, 2018, at 1:04 PM, Decker, Scott UTAS wrote:

> Joyce,
>   Thanks for the link, that was great! It answered many questions  
> and made more too... :-) (Side note, I couldn't get that link to  
> work, but I just put in the document name in Google and it came  
> right up.) Enjoy!
> Later...
>
> 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
> [log in to unmask]   www.utcaerospacesystems.com
>
> CONFIDENTIALITY WARNING: This message may contain proprietary and/ 
> or privileged information of
> UTC Aerospace Systems and its affiliated companies. If you are not  
> the intended recipient please 1) do not disclose, copy,
> distribute or use this message or its contents, 2) advise the  
> sender by return e-mail, and 3) delete all copies (including all
> attachments) from your computer. Your cooperation is greatly  
> appreciated.
> This Document Does Not Contain Export Controlled Technology Or  
> Technical Data.
>
>
> -----Original Message-----
> From: Yuan-chia Joyce Koo [mailto:[log in to unmask]]
> Sent: Tuesday, February 27, 2018 10:46 AM
> To: TechNet E-Mail Forum <[log in to unmask]>; Decker, Scott UTAS  
> <[log in to unmask]>
> Subject: [External] Re: [TN] Non Functioning pads
>
> https://urldefense.proofpoint.com/v2/url? 
> u=http-3A__www.dfrsolutions.com_hubfs_DfR-5FSolutions-5FWebsite_Resour 
> ces-2D&d=DwIF- 
> g&c=ilBQI1lupc9Y65XwNblLtw&r=Z5GKU9L_wgbp5uvPzUdN9HWtU4lRZiIaLoTaEwcy4 
> 0w&m=CL4to_9kQ9VA- 
> IpwSjgQlMsVVG1zhifwy71WAcrv1VU&s=Rsk0T9R4cNnpsMNYtaOMrBxIrY- 
> aid3yP9z1j_q6Wbk&e=
> 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
>> [log in to unmask]   www.utcaerospacesystems.com
>>
>> CONFIDENTIALITY WARNING: This message may contain proprietary and/ or
>> privileged information of UTC Aerospace Systems and its affiliated
>> companies. If you are not the intended recipient please 1) do not
>> disclose, copy, distribute or use this message or its contents, 2)
>> advise the sender by return e-mail, and 3) delete all copies
>> (including all
>> attachments) from your computer. Your cooperation is greatly
>> appreciated.
>> This Document Does Not Contain Export Controlled Technology Or
>> Technical Data.
>>
>> -----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