Hello Victor,
In a publication by Alpha Metals ("Failure Analysis of Solder Joints",
Ronald A. Bulwith), a good eutectic Sn-Pb etchant was described as 3 parts
acetic acid, 4 parts nitric acid, and 16 parts water. The etching time was
recommended to be a quick 1 - 2 seconds. This could be preceded by an etch
to remove mechanically disturbed material, define the Cu (PCB / leadframe)
microstructure a bit, and help define the Cu-Sn IMC layer. This was
specified as 6 parts NH4OH, 6 parts water, 1 part H2O2 solution (3%).
Best regards,
Leo
------------------------------------
Leo M. Higgins III, Ph.D.
Director of Applications Engineering
[log in to unmask]
3755 Capital of Texas Hwy-So
Suite 100
Austin, TX USA 78726
tel: 512-383-4593
fax: 512-383-1590
mobile: 512-423-2002
------------------------------------
-----Original Message-----
From: Victor G. Hernandez [mailto:[log in to unmask]]
Sent: Tuesday, June 01, 2004 9:43 AM
To: [log in to unmask]
Subject: [TN] SnPb Etchant and LF enchants
Fellow TechNetters:
Can anyone shares their experience with SnPb solder etchant, I want
to decorate the solder fillet to search for
potentials fractures after a Post reliability environment. SnPb is soft
and I don't want to overlook artifacts due to
smearing during the final polishing process. Once upon a time in a
previous life a co-peer instructed me to used a
Buehler Final Masterpolish with a pH of 9.
Victor,
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