Which solder paste to use for solder small stainless steel parts to pcb (SMT)

Equipment, Tools & Supplies Soldering, Desoldering, Rework Products
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Hi there,
Working at prototyping stage for a project, needed to solder a small stainless steel parts to PCB. I’ve tried use solder iron manually with silver solder which worked ok. However for SMT, wonder anyone know which type of solder paste should I use, will anyone with some silver work?

Thanks in advance.

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Welcome to the Digi-Key TechForum ryan2008.
I do not have any experience with soldering stainless steel. I found some listing on the internet that said the solder should contain at least 50% Tin for strength, and adding some Silver will make for a stronger bond. You can also try and contact some solder manufactures, like KESTER or MG CHEMICALS, for advise. Another option is to search on Google and Youtube to help with the decision.

Maybe someone else with some experience with this, may comment also.

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Hi @Ryan2008,

A good job requires good tools, and flux is a good tool for high surface-oxide solder joints.

Flux :

You will need a more powerful high activity acid flux designed for stainless steel because of the greater amount of oxides on the surface of stainless steel. These oxides are what prevents the solder from sticking to the surface.

Solder:

You will need silver bearing solder. Some silver-bearing solders contain an acid flux core but that is not always enough flux to get the job done. In these cases, you will need to add more (acid) flux to the joint to solder stainless steel, especially if using rosin cored solder.

Acid flux:
Click here for Acid flux CQ8LF-B-R | CQ8LF-1.0 | CQ8LF-0.5 | CQ8LF

Acid cored solder:
Click here for acid cored solder

Rosin cored solder:
Click here for 243-1360-ND | 243-1361-ND
Click here for all Rosin cored examples

-Please review datasheet information on products before ordering.

Reference:
https://blog.sra-solder.com/knowledge-base/can-you-solder-stainless-steel

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