James,

If you look in IPC-2221, 1.4 - you get a definition of 'shall' and 'should'.

Basically, shall is mandatory, and should is non-mandatory.

If it were me, I would add a note to my Fabrication saying something like...

"non-functional pads on inner layers shall not be removed during fabrication."

...or something like that. It then is a specification that YOU are invoking.

Regards,

James Jackson



Quoting "James, Ron CAR" <[log in to unmask]>:

> Senile designer needs help.  ;-) 
> 
> It has been a while since I have dealt with the question of removing or
> not removing non-functional pads from inner layers.  I can't seem to
> find any record of what I told our board fabricators in the past.  So I
> tried looking it up in the IPC specs. 
> 
> IPC-2222, 9.1.4 says that non-functional lands "should" be included on
> internal layers for all plated-through holes.  It says "should" where
> many other paragraphs say "shall" in bold type; I assume that was done
> deliberately?  Is this just a recommendation, and not a requirement? 
> 
> IPC-2221 only seems to mention non-functional lands in paragraph 12.4.1
> describing test coupons, where it says that the coupon shall represent
> the design except that non-functional lands shall be included on all
> layers.  The wording of this section suggests that non-functional lands
> would normally be missing, but they want them present on the test
> coupons. 
> 
> I can't find anything else, but I don't have a searchable PDF copy of
> the IPC specs, so there may be information that I am missing while
> flipping through my paper copy. 
> 
> A web search using the mighty Google shows multiple board suppliers who
> list removal of non-functional inner layer pads as a standard step in
> their CAM processing of customer Gerber files. 
> 
> I guess my question is:  what IPC spec can I refer to to tell the fab
> house that they shall not remove unused inner layer pads?  Or is it
> really OK? 
> 
> Ron 
> 
> 
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