Peter: You may want to check the TechNet archives there's a lot of
information on OSP coatings.

The coating itself is a reaction mechanism with the exposed surface copper
of the PCB. It forms be a uniform thickness on the holes and surfaces and is
pretty much self limiting. It is not like a paint or even a rosin type
coating that would have various types of build-up thickness at edges, lips,
large flat areas, etc. Where viscosity and topography can affect the deposit
thickness.

It is possible that extremely small vias may not have the same amount of
coating due to solution transfer and rinsing. However I've never found that
to be a problem.

What exactly is it that you are trying to determine?  Are you having process
problems? There are many things that can impact this and ways to measure,
test and overcome them depending on the situation.



Regards


Mike Barmuta

Staff Engineer

Fluke Corp.

Everett WA

425-446-6076

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Peter Verbiest
Sent: Thursday, March 25, 2004 1:18 PM
To: [log in to unmask]
Subject: [TN] Measuring OSP in PTH's


Hi All,
I have a need to better understand the distribution of OSP (i.e. Entek
Cu-106 A) along the wall surfaces of different size PTH's.
I would appreciate any literature, ideas, or recommendations on approaches
to collect such information.

Thank you,
Peter Verbiest

Jabil Circuit
San Jose, CA

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