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| Reply To: | (Leadfree Electronics Assembly Forum) |
| Date: | Fri, 8 Dec 2006 11:27:01 -0600 |
| Content-Type: | multipart/mixed |
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Ioan,
"What was really under the lead will remain unknown."
This can be rectified if you x-section the joint and measure for lead. A
small experiment with several components can provide average and variance
for the Pb %. Many years back, this process provided an excellent estimate
of Cu dissolution during rework.
pratap singh
____________________________________
Tel/Fax: 512-255-6820; Cell: 512-663-8903
www.rampinc.com ; EMail: [log in to unmask]
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Pearl,
I was in this situation and it is OK. Just make sure the wicking is thorough
and leaves really flat pads. We measured 4 to 10 % Pb on cleaned pads,
depending on the quality of wicking. But this is only a thin layer on top of
which you put a fair amount of new solder, which will dilute the Pb content.
The more solder you put, the better it is from this point of view.
After soldering the new components we measured Pb below 0.1%. The
measurements were in the bulk of solder present at the toe. What was really
under the lead will remain unknown.
Good luck,
Ioan
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]]On Behalf Of pearl petras
Sent: Friday, December 08, 2006 11:41 AM
To: [log in to unmask]
Subject: [LF] Contamination
So...
An assembly house installs one SnPb component on a leadfree assembly.
This has never happened to anyone else has it???
Two different assembly contractors in less than two months have done the
same thing. The first case, the customer was willing to accept RoHS 5
boards, so we never tested to determine whether there was unacceptable
levels of contamination.
Has anyone ever had testing done to see if Pb can be acceptably removed by
the following process:
Remove component with rework machine
Wick off all remaining solder from pads with soldering iron
Replace tip on iron
Hand solder new leadfree component with leadfree solder onto the board.
0.1%...I keep having 0.1% running thru my head...
---------------------------------
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