To: Edward Szpruch,

What's more likely is that the topic you asked about is a sensitive one.
Plating high aspect ratio blind vias is very much state of the art right now
and to stay
competitive, companies are struggling to develop processes to do just that.
They ae not
likely to divulge in an open forum exactly how to do it.

I suspect you'll find that to plate small holes at or beyond a 1:1 aspect
ratio you will have
to use a more exotic plating system with special agitation, special
high-throw brighteners,
low current density, and maybe even periodic reverse, pulse plating.

> -----Original Message-----
> From: Eltek Ltd. - Process Engineering
> [SMTP:[log in to unmask]]
> Sent: Wednesday, January 06, 1999 12:47 AM
> To:   [log in to unmask]
> Subject:      [TN] Plating of laser drilled vias
>
> Hi technetters ,
> I sent this meesage on 31 of December . Probably most of you were out of
> e-mail due to new year . This is the second trial .
> What are the  existing and working technologies for electrolytic copper
> and
> tin lead plating of blind vias , laser drilled ?
> We are testing now making tests with   0.2 mm diameter , 0.3 mm deep laser
> drilled vias . The stage of permanganate desmear and electroless copper
> plating was performed in vertical line without special efforts . We tried
> different current densities in vertical electrolylic stage , but we got
> very
> poor copper distribution along the wall : 20 microns in the upper part , 5
> microns on the bottom and on the lower part of the wall . We just presume
> ,
> tha the same problem will be for tin-lead stage of pattern plating .
> Best regards and Happy New Year 1999 !
> Edward Szpruch     Eltek Ltd - Israel e-mail :  [log in to unmask]
>

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