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They look like covers at first glance but they aren't stickered on. I've never seen pads like this and searching doesn't bring up any results. Any information on these?

enter image description here

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up vote 16 down vote accepted

It's a PCB finish, called Immersion Silver, or IS for short.

Some other common types of finishes:

  • Hot air-levelled solder (HASL) - Just your normal solder, levelled with hot air knives.
  • Electroless Nickel Immersion Gold (ENIG) - Your typical matte gold.
  • Galvanic Gold - Different type of gold finish, looks shiny and polished.
  • Organic Solderability Preservative (OSP) - Looks like bare copper.
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AFAIK galvanic gold is actually galvanic nickel-gold, you still need a diffusion barrier just as with ENIG. – Dmitry Grigoryev Feb 19 at 8:30

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