Brief introduction of hotbar process principle

Hot bar soldering is also known as pulse hot pressing welding, which is also known as hotbar welding in the industry, but most people in the industry call it directly: hotbar. The principle of hotbar is to first print solder paste on the pad of a circuit board (PCB), melt the solder paste and solder it on the circuit board in advance after reflow welding, and then place the object to be welded (generally FPC) on the circuit board already printed with solder paste, Then use the heat of the thermal indenter to melt the solder and connect the two electronic components that need to be connected. It is called hotbar because the flat object to be soldered (generally FPC) is soldered on the circuit board using a long hot indenter.

Hotbar usually solders flexible board (FPC) to PCB, so it can be light, thin, short and small. In addition, the cost can be effectively reduced, because 1 ~ 2 flexible board connectors can be used less. The principle of general hotbar hot press and Haba machine is to use the huge Joule heat generated when a pulse current flows through molybdenum, titanium and other materials with high resistance characteristics to heat the thermodes / heater tips, and then heat and melt the solder paste already on the PCB through the thermodes to achieve the purpose of mutual welding. Since the pulse is used for heating, the energy and time control of the pulse is very important. The control method is to use the thermocouple circuit at the front end of the thermal head to feedback the temperature of the thermal head back to the power control center in real time, so as to control the pulse signal to ensure the correctness of the temperature on the thermal head.