During SMT assembly process two common techniques for applying flux

Two common techniques for applying flux during SMT assembly include:

Dispensing

Impregnation

There are reasons and objections to using these two technologies. The main argument against the distribution of flux to the PCB is simple - it takes more time. Unlike impregnation, the components are directly immersed in a predetermined flux height in the transfer plate, and a certain amount of flux is dispensed directly onto the PCB during the stencil printing stage prior to placement of the components.

Although the time required to prepare each plate is increased, when impregnation is not possible - that is, when there is a limitation of SMT production equipment, dispensing may be a suitable alternative scheme . The flux distribution unit is also much less expensive than the flux transfer plate.

The impregnation technique consists of a squeegee and a flux transfer plate having a plurality of cavities that are etched to different depths. A scraper sweeps the flux across the cavity, filling it with flux. The device is then ready for the SMT device to pick up the components, immerse them in the designated solder cavity, and place them on the circuit board. This process is faster than dispensing alternatives, thus reducing overall manufacturing time and having the ability to improve accuracy and consistency.

Test result

As the saying goes, "The evidence is in the pudding," so once you've built the first board using any technology, it's best to check and test the output. The X-ray image of the board can highlight any shorts or solder bridges - however, for best assurance, we also recommend using horizontal and vertical slices. This inspection method highlights the connection between the pads, solder and components, allowing you to see the smallest defects.

FASTPCBA SMT Processing: As we explored in this article, competition for making smaller, faster, and more powerful products in the consumer world continues to affect industrial electronic products. Fortunately, many of the challenges associated with soldering SMT components that differ in solder height can be overcome through time, experience, and powerful build, test, and inspection processes.