I had seen this before, probably at Hackster when they reported on it a few years ago:
"... This project is a PCB that reflow solders itself and THEN can self-propagate RepRap style. The self-soldering PCB is a multi-layer design. One of the layers is a serpentine trace that acts as a resistor/heating element. Applying power to this trace and monitoring the PCB's self-rise temperature can generate enough heat to cause the solder paste to reflow. ...
The results are awe-inspiring. But what does THIS circuit do? When would a self-soldering board be practical? Turns out, the first board Bugeja reflowed was a heating controller! Like the RepRap 3d printer that can print itself, this self-soldering board can solder other boards! The idea is that you manually control the heat for the first one, and then it can create a proper reflow profile for future boards..."
You can read all about it at:
www.hackster.io/news/a-pcb-that-reflow-solders-itself-and-then-self-propagates-66b1edffc10d.amp
But the following article snippets are from Campus Component, which is an India electronics component store selling wholesale and bulk, and I think where the technology originated. It also provides link for the parts you need ...
Self-soldering PCBs - The Future of the Electronics Industry
20.03.23 By AKB
".... The real problem arises when suddenly your electronic device stops working, and no service centers are nearby. For these reasons, now we have self-soldering, where the soldering process is automated whenever there is a fault in your electronic device. ...
There are various benefits of self-soldering PCBS.
Higher quality soldering
... with the help of self-soldering, you can produce a high-quality output. ... Moreover, it reduces repetitive work that can gradually cause the device to malfunction. Therefore, if you are using an automated soldering system, it can eliminate errors, thus reducing wastage. ...
One of the most incredible benefits of using automated soldering is that you will know precisely the cost and output of a particular product. ... and, at the same time, increase the product's shelf-life. ...
Steps involved in self-soldering PCB board
It is advisable to start the initial soldering process with smaller components to get confidence in putting your hand in the bigger ones. Therefore, you must divide the soldering process into several sessions to make the end product accurate. .... also ensure that the components on the board are in the right place and not falling off. Keep your soldering gun, cutter, tweezer, and similar tools ready and near your hand. .... ..
Conclusion
Therefore, if you want to cut the extra expenses and simultaneously want a perfect electronic project, you must wash your hands from traditional soldering and imbibe self-soldering. The process is faster and, at the same time, makes the electronic device durable. .....
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Here's a YouTube video about it
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