Process for improving hole plugging recess of back drilling hole of printed circuit board

The invention relates to a process for improving a hole plugging recess of a back drilling hole of a printed circuit board, which comprises the following steps of: after a semi-finished printed circuit board is drilled and punched, carrying out ultrasonic water washing on the semi-finished printed circuit board; performing hole plugging on the printed circuit board semi-finished product subjected to the solder mask pretreatment by adopting a 110-mesh screen printing plate; performing solder mask exposure on the semi-finished printed circuit board subjected to solder mask printing; and performing solder mask development on the semi-finished printed circuit board subjected to solder mask exposure, and obtaining a finished printed circuit board after the solder mask development is finished. The process is few in process steps and easy to operate, and after the process is implemented, the reject ratio caused by the sunken plug holes can be reduced to about 1.0% from 5%-6% in the prior art. 本发明涉及一种应用于改善印刷线路板背钻孔塞孔凹