①Insufficient solder paste (partial lack or even overall lack) will lead to insufficient solder joints of components after soldering, component open circuit, component offset, and component erection。

②Solder paste adhesion will lead to short circuit and component deviation after soldering。

③The overall offset of solder paste printing will lead to poor welding of components on the entire board, such as less tin, open circuit, offset, vertical parts, etc.。

④ The tip of the solder paste is easy to cause short circuit after soldering。

1.2 The quality of the solder paste is abnormal, and foreign matter such as hard lumps is mixed with it.

1.3Solder paste that was not used up before has expired and was used a second time.

1.4 Board quality issues with inconspicuous overlays on the pads such as solder resist (green oil) printed on the pads.

1.5 The circuit board's holding grip in the printer is loose.

1.6 The thickness of the solder paste stencil is uneven.

1.7 Solder paste is missing from the stencil or there are contaminants on the circuit board (such as PCB packaging, stencil wipes, foreign objects floating in the ambient air, etc.).

1.8 The solder paste scraper is damaged and the stencil is damaged.

1.9 The equipment parameters such as the pressure, angle, speed and demolding speed of the solder paste scraper are not properly set.

1.10 After the solder paste is printed, it is accidentally knocked off due to human factors。