A multilayer printed circuit board having resinous insulating layers and
conductor layers alternately superposed on a circuit board with ample
adhesive strength, a method for the production thereof, and a curable
resin composition useful for the formation of resinous insulating layers
are disclosed. The manufacture of the multilayer printed circuit board is
accomplished by applying the curable resin composition to the surface of
conductor layer of the circuit board, thermally curing the applied layer
thereby forming resinous insulating layer, then boring a through-hole in
the circuit board, treating the resinous insulating layer with a
coarsening agent thereby imparting undulating coarsened surface thereto,
subsequently coating the surface of resinous insulating layer and the
inner surface of the through-hole with a conductor layer as by electroless
plating, and thereafter forming a prescribed circuit pattern in the
conductor layer. The curable resin composition comprises (A) epoxy resins
and (B) an epoxy resin curing agent as essential components thereof and
optionally contains a rubber component and a filler capable of being
decomposed or dissolved by a coarsening agent. This composition contains
in combination a bisphenol A epoxy resin having an epoxy equivalent of not
less than 400 and an epoxy resin having an epoxy equivalent of less then
400.