Analysis of the causes of printing defects in SMT patch assembly
1. Solder paste collapse and blur in SMT chip processing
1. The hardness of the scraper is too small, and the backside support is insufficient. The low hardness of the squeegee will cause the solder paste to be difficult to form, and the printed shape of the solder paste cannot be maintained during demolding, and the appearance is blurred
2. The solder paste viscosity is too low
3. The thickness of PCB assembly printing solder paste is too high
4. The printing template is not cleaned
SMT chip processing
2. SMT processing missed printing, incomplete solder paste printing
1. The template leaks are blocked
2. The separation speed is too slow. Solder paste has a certain viscosity at room temperature. If the separation speed is too slow, the solder paste will not be able to get off the screen well, which will not only make the pad not get enough solder paste, the printing is not complete, but it will also stain the screen.
3. The template opening is too small or the position is wrong
4. Poor rollability of solder paste
SMT chip processing
Three, solder paste graphics adhesion
1. SMT patch printing pressure is too large
2. The bottom of the template is not clean
3. The solder paste viscosity is low
4. The solder paste printing is too thick
5. Too many printing passes
6. The ambient temperature and humidity are too high
SMT chip processing
Fourth, the thickness of the solder paste printing is too thin
1. Too few printing passes
2. The template is too thin
3. The solder paste has poor fluidity and is not easy to roll on the template, resulting in too thin solder paste printing
4. The printing gap is too small
5. If the brushing speed is too fast, it is easy to cause difficulty in injecting the solder paste into the window, so that the thickness of the solder paste does not meet the specified requirements
6. Too much printing pressure