Disclosed is a method of fabricating a multi-layered PCB, in which the
optical waveguide component is inserted into the PCB in such a way that a prepreg
adhesive does not block an optical signal entrance of the optical waveguide. The
method comprises pre-routing a portion of an adhesive meeting the optical waveguide
to remove said portion, processing an adhesive weeping prevention layer so as to
prevent the adhesive from blocking the optical signal entrance of the optical waveguide,
arranging the optical waveguide, the adhesive, and the adhesive weeping prevention
layer on a copper clad laminate, and combining the optical waveguide, a prepreg,
and the adhesive weeping prevention layer with each other into a single structure.
The adhesive weeping prevention layer is selected from the group consisting of
a prepreg, a single-sided copper clad laminate, a thermally curable resin, a heat
spreader, and an unclad.