In these notes I wanted to share something that often goes unnoticed when restoring or examining older electronic devices: the presence of hazardous substances on circuit boards produced before RoHS existed. I recently opened a small FM receiver module from the early 1990s. At first glance, it looked perfectly normal — resin-coated PCB, tin-lead solder joints, and a simple RF front-end. But as I worked on it, I was reminded how different today's electronics are, especially because of RoHS rules.

RoHS (Restriction of Hazardous Substances) has become one of the most influential regulations in the electronics world, and restoring older equipment is a good way to appreciate its importance. Before the mid-2000s, it was normal to find lead-based solders, chromium-treated metal casings, and plastic components containing brominated flame retardants. All of this made manufacturing easy, but it also meant that disposing of these devices could release chemicals that linger in the environment for decades.