Hi Hugh,

        First I'd like to say that the request is ludicrous. In my
understanding of a finished hole size, this includes the plating, not just the
drilled hole. I would like to visit the PWB shop that has this kind of plating
control. The closest that one can come to this kind of uniformity would be
additive plating, and I doubt that this could be done across the entire panel.
        The drilling is another matter. I believe that you might approach this
at the drill level with mechanical drills, but no guarantee there either.
        Laser drilling, has a great place in today's technology, but my
experience indicates that this type of tolerance will not be met in drilling
through copper and polymer together.
        I do not know of device manufacturers that hold this type of
tolerances. I suppose that wire leaded discretes, might be close, but how many
boards in today's technology are being built with all discretes.
        Maybe you could invite this project engineer to spend some real time in
the board shop to understand the real world situations of board manufacture.

That's my two cents!

Regards,
Les
>  From: Hugh Scott Miller <[log in to unmask]>, on 12/3/98 12:10 PM:
>  Happy Holidays Technetters,
>
>  A recent project has entered our shop from a customer that is demanding
>  that all finished hole tolerances be held to +/- .001".  I pose the
>  following questions to the esteemed Technet panel:
>
>  a.  Are hole tolerances of +/- .001" realistic?
>  b.  How could a board shop with conventional drilling technology
>  in-house adjust its process to accommodate this request?
>  c.  What type of advanced hole formation  technology (laser, plasma
>  etching, etc.) could be applied to meet this requirement?
>  d.  Can a component manufacturer produce components with leads that are
>  within this tolerance?
>
>  Any and all suggestions would be greatly appreciated.
>
>  Regards
>
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