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PCBA Tech

PCBA Tech

Commonly used flux coating methods for pcba production
2021-10-04
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Author:Frank

Commonly used flux coating methods for pcba production
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Commonly used flux coating methods are divided into foam wave coating method, spray coating method, brush coating method, dip coating method and jet coating method. In the smt patch processing plant, the foam coating method and spray coating method are mainly introduced.


①The foam coating device is generally composed of a flux tank, a nozzle, and a porous foam tube immersed in the flux.


The foam tube should be immersed in the flux, and the distance from the liquid level is about 50mm. After a certain pressure of pure air is fed into the porous tube, a stable flux foam flow will be formed above the nozzle.

pcb

The PCB passes through the peak of the foam wave, so that a layer of uniform and controllable flux layer is coated on the soldering surface of the PCB.


In this device, the density control of the flux is very important. The quality of the flux peak formation depends to a large extent on the density of the flux, the pressure of the gas and the level of the flux above the foam tube.


②The spray coating method is divided into direct spray method, rotary spray method and ultrasonic spray method.


Direct spray method is also called spray method, which is only suitable for coating liquid flux with low solid content. Direct spray coating system usually consists of flux storage tank, spray head, air flow regulator and so on.


The rotary spray method is also called the rotary screen spray method. It mainly uses a part of a rotary screen made of stainless steel or other flux-resistant materials to be immersed in a flux container, and the net limit of the immersed part is filled with flux. This method is most suitable when the PCB adopts the long insertion method. The height of the component lead out of the PCB board surface can reach 5cm, and the foam wave peak coating method, the height of the lead wire exposed on the PCB board surface is usually limited to 1.5cm or less.


Rotary spray system usually consists of flux, rotating screen, slotted stainless steel pipe, air flow regulator and so on. The flux stuck in the holes of the rotating screen meets the high-speed airflow sprayed from the slot on the top of the stainless steel cylinder to form a coating on the lower surface of the PCB and the component area.


The ultrasonic spray method uses the cavitation effect of ultrasonic energy to turn the liquid flux into an atomized state and apply it to the soldering surface of the PCB.
The above is about the flux methods commonly used by PCBA processing manufacturers. If you need more industry information, please pay attention.