>
> Greetings fellow designers...
>
> A question has come up concerning the need for pads on both sides of the
> board for a plated via.  We have slipped and let a via get placed under
> a metalized part (big OOPS).  Now we are in the fix it phase and would
> rather not take the time or money to scrap and re-layout the board.
> What we would rather do is remove the pad on the top side of the board.
>
> I have always believed the need for pads on both sides of the board is
> mostly a fabrication issue to insure good/complete plating on the hole
> wall (at least on vias).
>
> My questions are:
>
> 1) What problems arise if the top pad is removed from the artwork?
>
> 2) What problems would there be if the pad was removed after
> fabrication?
>
> 3) Any other suggestions.
>
>
> Thanks in advance for your help and responses.
>
> Ben Davis
> [log in to unmask]

Greetings!

What you will risk by removing the pad from one side of the board is a breakdown
in the integrity of the PTH itself. The jagged edge introduced will be an open
invitation to oxidation and dendritic growth. Ultimately, the hole will fail.

Instead of removing the pad, perhaps it would be possible to tent over the hole
with solder mask, or introduce some type of insulator into the assembly
operation to mask the hole.


                                                        Regards,

                                                        Steve Horvath
                                                        Staff Engineer-PCB
                                                        Motorola, Inc.


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