Hi Fran
The amount of mask intruding into the hole will depend on the
application method. Our curtain coat operation can cause the mask (circa
1-2 microns) to penetrate about 1/3rd into the hole from both sides but
it has not affected the silver taking on the remaining surface. Is the
mask too thick at the hole entrance to prevent the plating solution
getting good access?
You may also need to confirm by micro section what your customer thinks
he is seeing. Is the mask covering all the hole surface? Hope this
helps.
Regards
Alistair
Alistair F Murray MICT
Technical Manager
Artetch Circuits Limited
England UK
Direct Dial: 01903-712931
www.artetch.co.uk
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Fran Juliot
Sent: 06 March 2007 15:58
To: [log in to unmask]
Subject: [TN] immersion silver and exposed copper in small vias
Our customer is questioning what they feel is exposed copper in 8 mil
vias holes on silver boards. We feel there is mask residue in the holes
which does not allow silver to take. These are holes that are allowed
to be plugged. Has anyone else ran into this issue with thier customers
and do you have the same look or are your small vias covered with silver
all the way through the via?
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