Youtuber develops self-soldering printed circuit boards
A youtuber has made his project to make self-soldering circuit boards open source. He uses one of the copper layers in a PCB as a heating element, allowing the PCB to heat up from the inside.
Carl Bugeja’s project can be found at his GitHub page, but you can also watch the accompanying YouTube video. The idea, like many good ideas, is simple: put power on a large resistor and you have a heater. In this case, the resistor forms a heating element that is hidden in the PCB like a spiral. To this end, Bugaja sacrifices one of the ‘ground planes’ in the pcb. Normally they are used to connect the components together. Bugeja uses printed circuit boards with four copper layers, so that another regular layer can serve as ground.
The first pcb that Bugeja developed is a controller for heating other printed circuit boards. The circuit uses a temperature sensor and pid controller to precisely control the temperature of the target pcb. The melting temperature of the solder paste he uses and the maximum temperature of the PCB material are quite close to each other. Simply driving high voltage and current through the circuit board can cause the layers to delaminate and even catch fire.
Incorporating the heat coil into a printed circuit board and letting it heat itself automates the soldering process. Soldering with a bolt yourself is not necessary and a hotplate or reflow oven for semi-professional soldering is also not necessary. However, all components must be pressed into place in the solder paste by hand, although a pick-and-place machine could also do that for you. These are also made by enterprising tinkerers themselves, for example with a 3d printer as a mechanism.
Bugeja warns that placing the spirals in the earth layer of the PCB can cause undesirable effects: the structure can serve as an antenna for radio frequency signals, which means that the technique is not suitable for every type of circuit. On the other hand, it is an almost free method for semi-automated production of printed circuit boards. The extra layer with spiral does not cost anything extra with most PCB manufacturers.