The scraping pit is in the process of solder paste printing, the scraper moves back and forth continuously, the scraper scrapes the lead-free solder paste at the opening of the stencil to form poor scraping, and the solder paste at the opening of the stencil is scraped away. This will lead to less tin on the circuit board. After reflow soldering, the solder joints with less tin have insufficient welding strength and lack the proper support for electronic components, resulting in welding defects. The occurrence of scraped pits and less tin can first rule out the reasons for the product quality of lead-free solder paste manufacturers. Usually, poor scraping pits are closely related to the processing process of SMT manufacturers. This defect is found in the actual process of bad production lines. It has a greater relationship with the solder paste printing stencil and the squeegee.

1. SMT lead-free solder paste factory printing squeegee is too soft

       Actually, the blade of the solder paste scraper used by SMT manufacturers is made of polyurethane material. If the hardness of the solder paste scraper is not enough, the soft polyurethane blade will deform during the lead-free solder paste printing process and insert into the opening of the steel mesh, causing the formed solder paste to be taken out. , resulting in the phenomenon of poor scratching.

2. Excessive pressure on the scraper causes deformation

       The blade used in the solder paste printing process is soft. If the printing pressure is too large, it will cause deformation, and the blade will appear uneven. The force is different to cause the phenomenon of scratching. If this kind of bad lead-free solder paste occurs, the manufacturer suggests that the production parameters of the production line can be adjusted, and the blade pressure parameters can be appropriately lowered.

3. The lead-free solder paste stencil is damaged

       The solder paste is evenly coated on the stencil. If the opening of the stencil is damaged during the actual printing process, it will cause the scraper to act on the stencil. , the solder paste in the stencil opening at the damaged position will be hung out, resulting in poor scratching.

4. The scraper blade is damaged

       The lead-free solder paste scraper is made of soft polyurethane. If it is damaged, the broken pipe will also cut into the opening of the stencil to scrape out excess solder paste, thereby reducing the amount of solder paste at the opening of the stencil.