Solder paste printing is a key step in the SMT process. To improve the solder paste printing quality, we need to focus on the below factors:
The printing speed
The solder paste takes time to roll and flow into the stencil opening. If printing is too fast, the solder paste will be uneven on the pad.
The pressure of scraper
The pressure of scraper is vital of solder paste printing quality. With small pressure, solder paste couldn’t reach the bottom of the stencil opening and get stored well on the PCB pad. Whereas too big pressure results in a thin solder paste and even damage the stencil.
The angle of the scraper
The angle of scraper influences the vertical force of the solder paste. The smaller is the angle, the bigger the vertical force of the solder paste.
The printing process parameter
Different printing parameters can affect the volume of the solder paste. There is a certain required balance between the speed, pressure, and angle of the scraper with the stencil and viscosity of the solder paste. By proper control of these parameters, it ensures a reliable solder paste printing quality.