The outside rim of this cymbal has not been cleaned, imagin leadframes in this condition - yuck!
Copper…
Lately I’ve been polishing the cymbals on my drum set, and it turns out to really be an art to clean them properly. Some of the cymbals shown here are around 10 years old and they have never been polished before. High quality cymbals are made out of 80-92%Cu and Sn. Just as we see with copper pads, Cu reacts with oxygen and other contaminants (like fingerprints). The cure for this phenomenon with cymbals is easy, it just requires a polishing solution to reduce the oxides and a lot of elbow grease. Copper traces, pads, and leadframes need to be protected so they don’t need to be “de-grunged”. Make sure you store these materials in a nitrogen dry-box when possible, and never touch them with your fingers.
Soldering processes have much less variability when copper surfaces are kept clean. Dirty surfaces can cause voiding, non-wets, and solder balling. Well, at least solder pads and leadframes aren’t hit repeatedly with a wooden stick!
Cymbals have a hard life, but your life can be a lot simpler if you handle copper and other soldering surfaces properly.