Hi,

We took an "A" coupon and covered 1 PTH using thermal resistant tape to prevent the solder
coming in contact with the hole and did a solder float on the remaining 2 holes. Although
this may not be exact verification of the thickness, the difference in plating thickness within
the 3 PTHs in an A coupons is <1microns.

Thanks!
U.Nagaraj
________________________________________
From: Louis Hart [[log in to unmask]]
Sent: Tuesday, August 19, 2014 7:57 PM
To: TechNet E-Mail Forum; Nagaraj U
Subject: RE: Query on Copper dissolution

My apologies for answering your question with a question, but how do you know the reduction is 20-25 microns?  I presume a measurement before the floats is not possible.  I'm interested to see what the experts have to say. Louis Hart

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Nagaraj U
Sent: Tuesday, August 19, 2014 1:59 AM
To: [log in to unmask]
Subject: [TN] Query on Copper dissolution

Hi All,

We have a few customers asking for 6x solder float at 288°C, 10 seconds (IPC-TM-650, 2.6.8, Condition A). After completion of 6x solder float (using SnPb 63/37 solder) we typically see reduction of Copper in PTH (due to copper dissolution) in the range of 20 to 25µm. The reduction in Cu thickness is maximum at the PTH knee area.

Can I have some inputs if this level of copper dissolution is normal?
If it is not normal, how do we reduce this?

Thanks in advance!

Best Regards,
U.Nagaraj
MICROPACK, India.
[Logo]<http://www.micro-pack.com>
[Logo]<http://www.micro-pack.com>

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