That's correct. We are gathering a lot of data to support the premise
that SAC soldering of Copper PTHs is a no-no.
Dewey

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dennis Fritz
Sent: Thursday, September 21, 2006 9:49 AM
To: [log in to unmask]
Subject: Re: [TN] Dissolving copper hole wall using lead free HASL?

Well, it stripped out the "cut and paste" from the pdf of Jasbir's slide
at
IPC.  Here is what he said on the slide:


During rework with SnAgCu alloy with copper from the PCB: copper
dissolves
with increasing contact time.

Experience: PTH barrel knee erosion after  20 seconds of solder pot
dwell time

Copper dissolution is a function of  original barrel/pad thickness,
solder
temperature and alloy (tin percentage),  dwell/contact time and solder
flow rate
and type of copper plating.

Studies are ongoing with dissolution rate comparison with various
lead-free
solder alloys and process optimization.


Denny Fritz

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