At the end of the day, PCB etching is all about removing copper from a board in as controlled a fashion as possible. PCB etching methods generally fall into one of two broad categories ...

If you compare a modern PCB with a typical 1980s PCB, you might notice — like [lcamtuf] did — that newer boards tend to have large areas of copper known as pours instead of empty space ...

This particular innovation, where a PCB is packed with stepped circular or rectangular copper coins, is headed to markets where even the best air coolers are impractical – like miniature devices ...