A YouTuber has made his project of making self-soldering circuit boards open source. It uses one of the copper layers in the PCB as a heating element, allowing the PCB to heat up from the inside.
Carl Bugeja’s project can be found at his site 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 hidden in the PCB like a coil. To this end, Bugaja sacrifices one of the PCB’s “Earth Planes”. They are usually used to connect components together. Bugeja uses four-layer copper printed circuit boards, so that another ordinary layer can be used as the ground.
The first PCB developed by Bugeja is a heating controller for other printed circuit boards. The circuit uses a temperature sensor and a pid controller to precisely control the target pcb temperature. The melting temperature of the solder paste he’s using and the max temperature of his PCB are very close to each other. Simply driving high voltage and current through a circuit board can cause the layers to loosen and even catch fire.
Incorporating the heat coil into the printed circuit board and allowing it to heat itself automates the soldering process. It is not necessary to weld the studs yourself, nor is a preheat or reflow oven necessary for semi-professional soldering. However, all components must be pressed into place into solder paste by hand, although a pick and place machine can also do this for you. They are also made by adventurous tinkerers themselves, for example with a file 3D printer as a mechanism.
Bugeja warns that placing spirals in a PCB’s ground layer can cause undesirable effects: The structure can act as an antenna for RF signals, which means the technology isn’t suitable for every type of circuit. On the one hand, it is an almost free method of semi-automated production of printed circuit boards. The additional screw-on layer costs nothing extra with most PCB manufacturers.
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