The aluminum PCB used in led flat panel light is coated

The aluminum PCB used in led flat panel light is coated with a non-conducting material and conductive copper trace lines to form the circuit board. Solder paste is then applied in the right places and then Surface Mount Technology (SMT) machines place the tiny LED elements, driver ICs, and other components onto the board at ultra high speeds.

The round shape of a traditional light bulb means that most led panel light Manufacturer printed circuit boards are circular, so for ease of handling several of the smaller circular PCBs are combined into one larger rectangular PCB that automated SMT machinery can handle. Think of it like a cupcake tray moving from one machine to the next along a conveyor belt, then at the end the individual cupcakes are snapped free from the tray.