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| Date: | Mon, 24 Jan 2005 14:24:15 -0000 |
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Thank you Susan, yes I think that may well be what I am looking at.
I can see the shape of the layers of laminate through the holes, although I cannot see the actual laminate as it is covered it is very lumpy.
Big holes are obviously worse, yet small holes show it too.
I must admit to not actually looking down a hole for a loooong time or since we converted to MacDermid silver plating. Looking with the microscopythingymabob I can see that Gold plated holes are nearly like that too.
I guess that it's just because the are not levelled off with the tin.
I have however asked my manufacturer to look at it & they are going to micro section a board
and measure the copper (most likely just to shut me up).
Thankyou,
Matthew Lamkin.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Susan Mansilla
Sent: Monday, January 24, 2005 2:17 PM
To: [log in to unmask]
Subject: Re: [TN] Silver plated barrel? does it reduce current carrying
ability?
You are probably used to looking at Hot Air Solder Leveled boards that have
solder as the surface finish. Solder "levels" an uneven surface. The various
immersion coatings do not do this so the topography of the hole wall is very
evident. The glass bundles may very well be completely covered with one mil of
copper, but would leave a "lump" along the hole wall. If your boards have
etchback you could see a lump at the inner layers. Some copper plating baths
also level their deposits, but most will give you an uneven topography.
Susan Mansilla
Robisan Laboratory
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