Hi Milind,

I would look critically  at the drilling operation as in my experience this
is the main source of hole blockages. What entry and exit materials are you
using. Debris from these or just glass fibres from the wall of the hole can
be difficult to see until after plating. Close inspection and
micro-sectioning of blocked holes should reveal the source of the blockage.
ie if it is metallic copper or foreign matter. Check the drilled panels
carefully with dim backlighting to see any fibres in the hole.
Using high quality new or refurbished (not resharpened) drills and aluminium
entry material coupled with the correct feeds and speeds and good extraction
are all important.

Good Luck


-----Original Message-----
From: Milind Rao <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: 14 May 1998 14:45
Subject: [TN] Particles in holes


>Sorry for my earlier mail without subject
>------------
>Hi
>We are getting particles in both component holes / via holes on and off
>and in double sided / multilayer boards. This is observed after pattern
>plating
>We use High build copper and Pattern plating.
>In some holes the particles are severe and reduce the hole size
>considerably. The problem is occuring very randomly.
>Has anybody got remedy for this ?
>Thanks in advance for the help
>Milind
>
>

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