Oxidized Silver on PCBs - How to Avoid it, and How to Fix it
Here at Bittele Electronics, we offer a range of different surface finishes including Gold Immersion (or ENIG), Lead-free HASL, OSP, ENEPIG, and Immersion Silver. Our default standard finish is Gold Immersion or ENIG, however, Immersion silver is a great alternative that can just as effective for no extra cost while giving your boards the look you want.
The main consideration when using immersion silver, although being a great alternative to gold immersion, silver immersion introduces the possibility of oxidation. We do take steps here at Bittele to avoid this. Bare hand contact with the boards is eliminated by the use of gloves as this finish is very sensitive to tarnishing. Special packaging must always be used. Boards with this surface finish are required to be packaged in vacuum-sealed, airtight plastic bags and they are packaged as soon as possible with minimal exposure to the air after the coating. This is to prohibit the boards from naturally tarnishing as they come to contact with open air, especially with chemicals that can be present in the production facility. We generally do not bake any boards with this finish, and we only keep boards stored for a maximum of 3 months to avoid oxidization.
If tarnishing or oxidization does occur, an effective method to remove the oxidation would be by using a low-pressure gas plasma treatment. Using Hydrogen (with less than 10% mixed with Nitrogen) and Argon, a precise mixture can be used to reduce the oxidized layer, depending on the composition and thickness of it. The gas plasma treatment will remove oxide and contamination regardless of what the main source is that caused it.
Silver immersion is just one of several surface finishes Bittele offers at our Standard Price.