/PCBA production commonly used flux coating methods
Commonly used flux coating methods are classified into foam wave coating method, spray coating method, brush coating method, dip coating method, and jet coating method. Here, the FASTPCBA SMT processing plant focuses on the introduction of foam coating and spray coating.
1.The foam coating device is generally composed of flux tank, nozzle, porous foam tube immersed in the flux. The foam tube should be immersed in the flux, about 50 mm from the liquid level. When a certain amount of pure air is fed into the perforated tube, a stable flux foam is formed above the nozzle. The PCB passes through the peak of the foam peak, thereby applying a uniform thickness and controllable flux layer on the PCB soldering surface. In such a device, the density control of the flux is very important, the quality of the flux foam peak formation depends to a large extent on the flux density, the gas pressure and the flux liquid level above the foam tube.
2.Spray coating methods are divided into direct spray method, rotary spray method and ultrasonic spray method. Direct spray method, also known as spray method, is only suitable for coating liquid flux with low solid content. Direct spray coating systems typically consist of flux storage tank,spray head,damper. The rotary spray method, also known as spray spinning method, mainly uses a part of a rotary screen made of stainless steel or other flux-resistant material to be immersed in a flux container, and the wire in the immersed portion is filled with flux. This method is most suitable when the PCB is inserted in a long insertion mode. The height of the component leads extending from the PCB surface can reach 5 cm, while the foam wave coating method, the height of the lead exposed PCB surface is usually limited to 1.5 cm or less. Rotary spray systems typically consist of flux, rotating screen, a slotted stainless steel tube, a damper etc. The flux adhered to the rotating screen mesh meets the high-speed airflow ejected from the slot of the stainless steel cylinder to form a coating on the lower surface of the PCB and the component area. Ultrasonic spray method utilizes the cavitation of ultrasonic energy to make the liquid flux atomized and applied to the soldering surface of the PCB.
The above is the common flux coating method for PCBA production provided by FASTPCBA. Hope it’s helpful to you!
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