From time to time the question comes across my desk about soldering stainless steel wire, contacts, or other surface with the solder we carry here at Digi-Key.
The issue with this question is not the fact that it can not be done, but that you need an acidic flux to solder stainless steel and for what should be obvious reason acid flux is not recommended in electronic applications.
Kester even comes right out on their site and says they do not recommend soldering to stainless steel in this document. (Soldering_to_Stainless_Steel.pdf (17.4 KB) ). David Scheiner goes on to talk about what your options are if you NEED to solder solder stainless steel you will have a couple options.
- Use a mechanical connection
- Use a plated stainless Steel
- In a non-electrical/electronic situation (Mechanical) you couple look at an acid Flux such as Kester 817.
So what is the secret to soldering stainless in electronics then? David also covers this and its simple there is no secret. If you have seen it you have likely either seen a nickel plated stainless which can be soldered with electronics solder or you have seen a joint that was soldered with an acidic flux. The problem with this joint is that the corrosion that allowed the solder to adhere to the stainless steel is slowing continuing to corrode the joint and will slowly dissolve the connection.
There are a few places out there that will say it can be done and will not mention that this is a short term solution. It this case the mechanical solution will likely be the best bet for a reliable connection.