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From:
Dwight Mattix <[log in to unmask]>
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TechNet E-Mail Forum <[log in to unmask]>, Dwight Mattix <[log in to unmask]>
Date:
Mon, 5 Mar 2018 16:58:10 +0000
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Or stated in the vernacular "drilling a lot of layers with non-func pads present makes a real mess of the hole" 



:)



-----Original Message-----

From: TechNet [mailto:[log in to unmask]] On Behalf Of Jose A Rios

Sent: Monday, March 5, 2018 8:51 AM

To: [log in to unmask]

Subject: Re: [TN] Non Functioning pads



I refer to you all again to the guidance requirements in the design specs, IPC 2222A, section 9.1.4 and Table 9.2 where theres an allowance to remove under certain conditions (the dinosaur set was part of formulating those).

On drilling thru a lot of copper, you’re reconciling the presence of non functional lands against possible laminate fracturing, gauges and lateral plating that results (wicking, etc); more so if etchback is required…. regardless of drill life.





José (Joey) Ríos, Sr QA Engineer

Mission Assurance Manager

Kavli Institute for Astrophysics & Space Research Massachusetts Institute of Technology [log in to unmask]<mailto:[log in to unmask]>

(617)324-6272











On Mar 5, 2018, at 11:11 AM, [log in to unmask]<mailto:[log in to unmask]> wrote:



Dell - Internal Use - Confidential





 That was my basic training guide.   Back in the early 80s



Victor,



-----Original Message-----

From: TechNet [mailto:[log in to unmask]] On Behalf Of Yuan-chia Joyce Koo

Sent: Monday, March 5, 2018 10:01 AM

To: [log in to unmask]<mailto:[log in to unmask]>

Subject: Re: [TN] Non Functioning pads



well said dinosaur... look like we are similar vintage...

On Mar 5, 2018, at 10:48 AM, Jack Olson wrote:



I must be behind-the-times on this one.

Werner Englemaier used to talk about this all the time, and from my memory an analogy might be similar to comparing a simple rivet to a "rivet with ribs". If your goal is a robust product (which a lot of Class 3's are) then it seems like you would want the extra support.

(I'm not making a statement, I'm repeating what I was taught). I'm pretty sure I've heard Gary Ferrari recommend keeping them in at least a half a dozen times in his seminars. Aren't the most common failures in boards related to vias?



Maybe I have more learnin' to do on this one, but I'm surprised that NO ONE responded in favor of keeping the unconnected internal pads



Well, since we are talking about vias, I was also advised to require 1mil hole wall plating, even though the standard is 0.8 (I think). But for the same reason, the stronger we can make our vias, the less "most common" failures we will have, right? (At Caterpillar, we want the most robust product we can get for the

money) Am I sounding like an old dinosaur now?



but really, is EVERYONE removing unconnected inner layer pads?

Is "increasing the longevity of drill bits" the dominant theme now?



onward thru the fog,

Jack





.

On Tue, 27 Feb 2018 11:12:22 -0600, Larry <[log in to unmask]<mailto:[log in to unmask]>>

wrote:



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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