While it's possible to buy ready to use tinning formulas, making your own is much less expensive. Various recipes exist for tinning copper, today I will present a simple one that uses ingredients available at online chemical stores. Ingredients:
Citric acid can be substituted for tartaric acid. An alternative recipe, which is used commercially also (sold as dry product), is to use sulfamic acid, if you can get it. Its commonly sold as descaler for steaming irons and kettles. 4g Thiourea 1g Stannous chloride 6g Sulfamic acid 200 ml distilled water Water can be heated to 50 C to aid solubility, but must be cooled to room temp before use. I'm investigating adding a brightener such as glutaraldehyde in very small quantity, to the above, but its not required really. Simply put PCB into the solution and wait a couple of seconds, the more time the PCB is in the solution, the thicker a tin layer is. It's not needed to heat up the solution - room temperature is sufficient. The first PCB that I tinned this way is presented below. Solder wets the surface easily.  |
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