Oops! I was chemically obtuse.
Ethylenediamine tetraacetic acid, disodium salt.
It is a common coordination compound for metals. A cousin, NTA, was
used a lot in the 70's for detergents.
Bev
-----Original Message-----
From: Bev Christian
Sent: Tuesday, July 24, 2007 1:33 PM
To: 'TechNet E-Mail Forum'; 'Macko, Joe @ IEC'
Subject: RE: [TN] Question - solderability issues with Sn90Pb10 plated
0402 caps
Joe,
You do not say if the failure rate is 100% or 10 DPMO. Even if were
1000 it could very well be that one test would show it passing and other
failing. Statistics are alive and well.
If you had some EDTA you could wash a considerable number of the parts
and then run them through the line with and without the EDTA treatment.
If the washed ones work and the others don't you know it is the parts
and not the process.
Bev
RIM
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Macko, Joe @ IEC
Sent: Tuesday, July 24, 2007 1:13 PM
To: [log in to unmask]
Subject: [TN] Question - solderability issues with Sn90Pb10 plated 0402
caps
Good morning All.
One of our CMs is experiencing either non-wetting and/or dewetting on
the end cap(s) of some 0402 capacitors provided by 2 different
manufacturers. One Cap manufacturer plates using Sn90Pb10 and the other
plates using SN95Pb5. The smt CM is using Kester Hydromark 531 WS,
Sn63Pb37 paste. The profile is obviously a SnPb type profile.
Samples of each caps were sent to an outside lab for a solderability
test and both failed a Dip and Look Solderability test per J-STD-002B -
see attachments. However, both Cap providers informed us that their
samples passed their Dip and Look solderability test.
Question -- Subsequent smt runs using the same paste type and profile
but with "pure tin" plated capacitors showed no evidence of either
wetting or de-wetting, which begs the question, what is different about
these Caps that cause the wetting/dewetting issues. Plating?????
Look forward to anyone's comments, experience, etc... People either
think it is capacitor issue or a smt process issue. thanks
-Joe
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