METHOD OF PRODUCING PRINT BOARD

A sealing film (12) that is to be attached to a print board (10) when supplying filling material (16) into through holes (11) of the print board (10) with a printing method under a vacuum atmosphere, the sealing film (12) being to be attached to the print board (10) from an opposite side from a filling material supplying side and separated from the print board (10) before starting a curing of the filling material (16), the sealing film (12) being made of synthetic resin and having a thickness being from 35 µm to 100 µm , the sealing film (12) comprising: a base film (12A) that has a smooth surface, the base film (12A) including micro holes (12C) having a diameter being from 10 µm to 100 µm and arranged at intervals of 2 mm to 4 mm; and an adhesive layer (12B) divided into adhesive layer (12B) portions that have a diameter being from 100 µm to 500 µm and are disposed on the base film at intervals of 10 µm to 400 µm.