Patent attributes
A production method capable of stably producing a prepreg and a copper foil with thin insulating layer using a thin backbone material capable of securing excellent laser hole-making property. A method for producing a prepreg for use in producing a printed wiring board having a backbone material impregnated with a thermosetting resin comprising the following steps is adopted:(1) a liquid resin coat forming step for forming a liquid resin layer on a flat work plane using a liquid thermosetting resin;(2) a pre-drying step for changing the liquid resin layer to a dry resin layer;(3) a backbone material pre-adhesion step for heating and pressure bonding the backbone material on the above described dry resin layer on the work plane to form a dry resin layer with backbone material;(4) a resin impregnation step for heating the dry resin layer with backbone material to a temperature where the resin is reflowable, and impregnating the backbone material with the resin component; and(5) a cooling step for carrying out a temperature decreasing operation immediately after finishing the resin impregnation, and maintaining a half-cured state of the thermosetting resin impregnated in the backbone material to form the prepreg. A method for producing a copper foil with insulating layer in the similar manner is further provided.
