Solder paste printer printing as the first process of SMT process, the quality of printing will have a very important impact on the subsequent processes. In the actual solder paste printing process, there is often a problem that the solder paste is not scraped clean, and the problem that the solder paste is not scraped clean is mainly due to the following reasons.
1. The temperature of printing
In cold weather, the viscosity of the solder paste will become larger, so the temperature of printing will have a great impact on the printing effect. When the solder paste can not be scraped clean, check whether the temperature of the workshop is within a reasonable range.
2. The quality of the squeegee
In the printing, the quality of the squeegee is very important. Some manufacturers in order to reduce costs, choose some poor scraper, the material of this scraper is generally not regular good, it will be easy to deformation, resulting in insufficient pressure, scraping is not clean.
3. Solder paste viscosity
In the solder paste stirring, solder paste is not stirred properly, the viscosity is too large will not scrape clean. There is also the solder paste placed in the air for too long, the solder paste becomes dry, will also cause the problem of scraping clean.
4. the parameters set
Solder paste is not scraped clean with the parameters set by the equipment will also have a great relationship, the speed of the scraper is too fast, the height of the scraper is too high, resulting in small pressure, there is a PCB and stencil spacing is too far away, are prone to scraping the problem.
5. the number of times the stencil is used
Solder paste scraping clean with the tension of the stencil also has a relationship, in general, the number of times the stencil scraped over 100k 150k, this time the printing is prone to problems.
Solder paste scraping this problem, is caused by many reasons, too much solder paste will also cause the problem of scraping clean, but these problems are mainly due to the four aspects of the solder paste, scraper, stencil, the parameters of the printing machine, when scraping clean, from these four aspects of analysis, generally solve the problem.
