We wonder if [Carl Bugeja] was looking at a 3D printer’s heated bed when he got the idea to create a PCB reflow heater using a PCB. He tried a quick test to heat up a standard PCB and made it self-reflow. That worked, though it obviously wouldn’t be practical for all boards. But it proved he could make it work.
To improve the heating performance, he laid out a metal core PCB, along with some custom control electronics. The board’s resistance didn’t quite perform to calculations, but luckily, it was too high so a shunt wire was able to reduce the overall resistance. One important thing to consider is that the heater board needs to use higher temperature solder so it doesn’t desolder its own components
We were glad to see [Carl] use a metal core board as standard PCB material can get cranky at high temperatures over 130C. Even so, it would be good to check the boards you plan to use this way to make sure they are rated for the kind of temperatures required.