[SpikedCola]

For disassembly practice, I used to collect broken electronics, and desolder various components for fun. You learn the different heat requirements of eg 2 layer boards vs motherboards with many layers.

For assembly practice, you can buy "SOIC breakout boards", the cheapest chips you can find, and go to town. Either with a solder stencil and some paste, or a syringe of paste and a blunt needle (this gets old fast!)

Coatings tend to make lots of nasty fumes when heated. Some can also prevent solder from wetting the pads or legs. Depending on the coating, overheating/burning may change its electrical properties.