Wave soldering machine is a commonly used equipment in the electronics industry. It has an indispensable role in PCB processing like reflow soldering. So what is the working principle of wave soldering? What is the difference between it and reflow soldering?
What is wave soldering?
Wave soldering is to contact the molten high-temperature liquid tin with the soldering surface of the PCB board pin components to achieve the purpose of soldering. Let the liquid tin form a slope, and a special device makes the liquid tin form a wave-like phenomenon, so it is called “wave soldering”.
The working principle of wave soldering:
Use a pump to spray the molten solder into a solder wave, and then pass the pins of the electronic components that need to be soldered through the solder wave to realize the soldering of the electronic components and the pcb board. The wave soldering machine is mainly composed of conveyor belt, flux adding zone, preheating zone, tin furnace and cooling. The conveyor belt is a device that transports the PCB board to the wave soldering machine, and the circuit bottom board passes through the flux adding area, preheating area, tin furnace, etc. all the way. The flux adding area is composed of two parts: infrared sensor and nozzle. When the circuit board enters, the infrared sensor will sense it and measure the width of the circuit board. Then the flux is formed on the soldering surface of the circuit board to protect the film.
The preheating zone provides enough temperature for the solder to form a good solder joint on the solder surface. Infrared heating can make the circuit board heat evenly. First, the solder penetrates through the slits of the pins at a high speed, and the spraying direction of the solder is the same as that of the circuit board. The first wave crest cannot completely solder the component. It will leave an uneven solder surface and excess solder to the solder joint. Therefore, a second wave is required. The second wave crest eliminates the burrs and burrs generated by the first turbulent wave. Welding bridge, therefore, when the traditional components are welded on a machine, the turbulent wave can be turned off and the traditional components can be welded with laminar waves. After the soldering is completed, due to the influence of thermal energy, the residual heat on the PCB will continue to increase its temperature, which will affect the performance of the components and reduce the bonding strength of the copper foil on the PCB. Therefore, the cooling system must be used to accelerate the cooling , Otherwise it will cause various bad solder joints to the wave solder joints.
The difference between wave soldering and reflow soldering:
- Reflow soldering is suitable for SMD electronic components, and wave soldering is suitable for pin electronic components.
- Wave soldering uses molten liquid solder to form a wave crest to solder the components; reflow soldering uses high-temperature hot air to form reflow and melt the solder to solder the components.
- Reflow soldering has been applied with solder through the tin printing machine before the pcb furnace, but the pre-coated tin green is melted and soldered by high temperature; the wave soldering is not coated with solder before the pcb furnace, but through The solder wave generated by the soldering machine is applied to the soldering pad to complete the soldering.
In the production of SMT, the wave soldering machine and the reflow oven each have different functions. Usually, many boards are used for both. Generally, they are first mounted (no feet, surface mount), then reflow soldering, and finally After the plug-in (with feet), pass the wave soldering machine.
