What Factors Should Be Considered When Soldering Paste In PCBA Processing？

Publish Time: January 05,2019

With the rapid development of component assembly, more and more PBGA, CBGA, CCGA, 0201, 01005 resistance and capacitance components have been widely used, and surface mount technology has also developed rapidly. In its production process, solder paste printing The influence and role of the entire production process of PCBA processing are increasingly valued by engineers. Therefore, pay attention to the following factors when choosing solder paste:

1. The viscosity of solder paste

The viscosity of the solder paste is an important factor that affects the printing performance. The viscosity is too large, the solder paste is not easy to pass through the opening of the template, the printed lines are incomplete, the viscosity is too low, it is easy to flow and collapse, affecting the resolution and lines of the printing Flatness.

To make the solder paste have good viscosity characteristics every time it is used, the following points need to be achieved:

(1) During the process of returning from 0 ℃ to room temperature, sealing and time must be guaranteed

(2) It is best to use a special stirrer for stirring

(3) The production volume is small, and the solder paste is used repeatedly, so it is necessary to formulate strict specifications

2. The viscosity of solder paste

The viscosity of the solder paste is not enough, and the solder paste will not roll on the template during printing. The direct consequence is that the solder paste cannot completely fill the openings of the template, resulting in insufficient deposition of solder paste. If the viscosity of the solder paste is too large, it will cause the solder paste to hang on the wall of the template hole and not be completely printed on the pad. The selection of the viscosity of solder paste generally requires that its self-adhesive ability is greater than its adhesion to the template, and its adhesion to the template hole wall is less than its adhesion to the pad.

3. Uniformity and size of solder paste particles

The particle shape, diameter and uniformity of solder paste solder also affect its printing performance. Generally, fine-grained solder paste will have better definition of solder paste prints, but it is prone to sags, and the degree of oxidation and the chance are also high. Generally, pin spacing is one of the important selection factors, while taking into account both performance and price.