Thanks Steve,

Would 0.010" over the finished hole size be good pad size to be used on internal
layers?

Thanks,
Pat




Stephen Gregory <[log in to unmask]> on 01/11/2002 02:33:46 PM

Please respond to "TechNet E-Mail Forum." <[log in to unmask]>

To:   [log in to unmask]
cc:    (bcc: Patrick Lam/SEL)
Subject:  Re: [TN] Remove unused "dead" pads on internal layers



Hi Pat!

I don't think it's a good idea, we got burned by it once. The internal pads
will provide support during drilling, and will help prevent rough walls
during drilling.

In our case, the unused pads were removed (this was a fairly thick ~.093" or
so polyimide PCB) and plating chemicals were absorbed into the fibers from
the rough drilling. We built the boards, did ICT and a low power functional
test, everything was fine. The boards were shipped to our customer and they
plugged it into their system, powered it up, and then the board died after
about 20-minutes, internal short in the fab. They RMA'd the board back to us,
we sent it out for cross sectioning and found the problem.

Had the used pads put back in and haven't had a problem since.

-Steve Gregory-


> Hi TechNetters,
>
> For class 3 boards, is it acceptable to have unused pads removed on
> interanal
> layers.
>
> Thanks,
> Pat
>













This e-mail may contain SEL confidential information.  The opinions expressed
are not necessarily those of SEL.  Any unauthorized disclosure, distribution or
other use is prohibited.  If you received this e-mail in error, please notify
the sender, permanently delete it, and destroy any printout.  Thank you.