| |
Letter 38033
Matte Sn discolouration
+++++
Hi ,
we are using matte Sn over nickel underplate.
For the solderability application, the product sees a temperature in
excess of 232C (Sn melting pt).
For cycles greater than 232C, I see the matte Sn discolour is shades
of yellow to brown.
Could someone shed light as to the cause of the discolouration.
Ali
Sharaf Ali
electronics assembly - San Diego, CA, USA
+++++
Mr Sharaf Ali.
It is likely the plated Matte Tin solution is organically overloaded
with either bult up impurities or excess brightener, both of which
tend to co deposit and then oxidise to the brown you see,when exposed
to high temperatures.
Warm the solution to 35 or 40 centigrade , Run 3 to 4 grams per liter
carbon for 4 Hours and filter our by decantation or filtration. This
removes excess brightener and most of the organic impurities.
It should help.
Regards
Dear Reader, please --
- Answer or follow-up on this subject (in non-commercial
fashion).
-
- My company is a supporting advertiser at
finishing.com and we want the contact information to reach
the inquirer privately.
-
- Post a new
question or inquiry on a different subject.
-
 |