The invention relates to a PI protective film uncovering method of a rigid-flex
printed circuit board, which is suitable for uncovering more than 6
layers of rigid-flex printed circuit boards, and comprises the following steps of manufacturing PP by using a high-
gummosis prepreg,
burning out a slot with a certain slot width by using a
UV laser machine to perform PP windowing, enabling the PP windowing to be located at two sides of the rigid-flex boundary and dividing the rigid-flex boundary into two parts, when the
copper layer corresponding to the PP is used for manufacturing a circuit, completely
etching off the
copper sheet corresponding to the area 0.4 mm away from the inner edge of the PP, attaching a PI protective film to the bottom of the PP on the bottommost layer, enabling the PIprotective film to be located in the flexible board area and be 0.25 mm away from the rigid-flex boundary, sequentially stacking and pressing the PI protective film, at least one layer of PP and a layer of
copper foil on the flexible board to which a covering film is attached, conducting outer layer manufacturing, and in the outer layer manufacturing process, conducting depth-controlled uncoveringthrough a CO2
laser procedure after character printing. The PI protective film uncovering method of the rigid-flex
printed circuit board has the advantages of being high in efficiency, good in quality and the like.