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How to improve the solderability of tin electroplating?
(to provide context, hopefully helping readers more quickly understand the Q&A's)
A pervasive general problem is that customers will demand bright tin plating, but the organic brighteners which bright tin requires interfere with solderability. So don't use bright tin plating unless you have to; and if you must, then use the absolute minimum :-)
Current question:January 3, 2022
Recently I began to have problems with pieces coated with bright tin -- the main problem is that when doing the solderability test, it did not adhere properly.
We have tried to attack the problem by changing chemical solutions such as degreasers, activated (HCl), and we have even changed the tin solution to rule out contamination.
We have even changed the flux and the solder of the pot where we do the test.
Any recommendation or observation that you can give me? The same thing happens with the client when they perform the test.
I really appreciate you advice.
- Matamoros Tamaulipas, Mexico
Closely related Q&A's, oldest first:2002
Q. We have problem about pure bright tin plated on brass, we found soldering failure (condition used 60/40 Pb/Sn flux, 400-420 °C, 3 sec.) when plated sample have insert in polypropylene after have soldering this layer was peel off. How I can solve this problem, Sorry about my English.
Matsushita Electric Works, Ayuthaya - Thailand
A. I suggest you should give a under coat of Nickel (3-5 microns) before plating bright Tin. Further, 60-40 can perform well at 230 °C, you need not have such a high temperature for your operation. Hope this should help solve your problem.
Good luck,Karthik [last name deleted for privacy by Editor]
A. As suggested by Karthik, use a Nickel undercoat and reduce the soldering temp. The liquidus temp for a pure tin alloy is 232 °C and the liquidus temp of 60/40 is 188 °C. Soldering at the temperatures you have stated will almost certainly be damaging to your tin plate. A nickel undercoat and a soldering temp of 230 should be sufficient.Rich Mosley
Q. I am a post-education in Beijing. My project is acidic Tin electroplating, The tin plating is bright, and passed the salt spray test. But the solderability is bad, I need some advise to deal with this problem.MENG HUI
student - Beijing, China
A. Sounds like you have an organic brightener film left on the tin surface. Try an alkaline cleaner after tin plating, and try to reduce the brightener concentration in your tin bath.
Jeffrey Holmes, CEF
Spartanburg, South Carolina
A. The two major killers of soldering tin are too much brightener in the plate- use matte tin if you want better solderability and two: tin oxidizes over time and it takes an aggressive flux to break thru the oxide enough to let the joint "wet".James Watts
- Navarre, Florida
Thanks! The solderability was improved by alkaline cleaner. I have found the tin plating was loose by SEM! My project is to obtain tin bright plating -- matte tin is not allowed.
Q. How to avoid the tin oxidizing?MENG HUI
- Beijin, China
A. Yes, I have dealt with customers who demand bright tin plating and then complain that all the 10 platers that they have used have a bad product because it will not solder after a month on the shelf. Plate with the absolute minimum amount of brightener that will work. You will also probably have to dump the bath more often than you would like. Anti oxidize-- The only one that I have heard of is a dilute solution of stearic acid in xylene. Sorry, I do not remember the ratio. I originally got it from an old mil or ams specification.James Watts
- Navarre, Florida
Thanks, Mr.Watts! I will do it by your advice, and tell you the result!Meng Hui
- Beijing, China
I'm Malina Jaafar from Malaysia.I'm working at plating company in Research and Testing Department. We are currently having problem with tin copper (SnCu) plating over Ni-Ag part when it failed the solderability test done. We have tried different Sn bath and even changed the activation and neutralization throughout the plating process without success. Does anyone have any ideas as to the root cause of these problem?
plating company employee - Shah Alam, Selangor Darul Ehsan, MALAYSIA
Or see these related threads:
• Topic 0958 "Soldering problems with bright Tin Plate"
• Topic 48893 "Required Bright Tin Plating Thickness for Soldered Parts"