Dry film and multilayer printed wiring board

Abstract

A dry film includes a supporting base film and a thin membrane of a thermosetting resin composition. The thin membrane of the thermosetting resin composition is formed on the supporting base film. The thermosetting resin composition includes a liquid epoxy resin, a solid epoxy resin, a semisolid epoxy resin, an epoxy curing agent and a filler. The liquid epoxy resin is liquid at 20° C. and has at least two epoxy groups in a molecule. The solid epoxy resin is solid at 40° C. and has at least three epoxy groups in a molecule. The semisolid epoxy resin is solid at 20° C. and liquid at 40° C. and has at least two epoxy groups in a molecule. A ratio of mass of the liquid epoxy resin to a sum of mass of the solid epoxy resin and mass of the semisolid epoxy resin is about 1:1 to about 1:10 A ratio of the mass of the solid epoxy resin to the mass of the semisolid epoxy resin is about 1:0.5 to about 1:2.

1 . A dry film comprising:
 a supporting base film; and   a thin membrane of a thermosetting resin composition formed on the supporting base film, the thermosetting resin composition comprising:
 a liquid epoxy resin being liquid at 20° C. and having at least two epoxy groups in a molecule; 
 a solid epoxy resin being solid at 40° C. and having at least three epoxy groups in a molecule; 
 a semisolid epoxy resin being solid at 20° C. and liquid at 40° C. and having at least two epoxy groups in a molecule; 
 an epoxy curing agent; and 
 a filler, 
   wherein a ratio of mass of the liquid epoxy resin to a sum of mass of the solid epoxy resin and mass of the semisolid epoxy resin is about 1:1 to about 1:10, and   wherein a ratio of the mass of the solid epoxy resin to the mass of the semisolid epoxy resin is about 1:0.5 to about 1:2.   
     
     
         2 . A multilayer printed wiring board comprising:
 an inner layer circuit substrate;   a conductor layer having a predetermined circuit pattern; and   a resin insulation layer comprising a cured coating of a thermosetting resin composition, the conductor layer and the resin insulation layer being alternately provided on the inner layer circuit substrate, the resin insulation layer having a boundary face which has a microscopic concave-convex roughened surface and to which the conductor layer is bonded, and the thermosetting resin composition comprising:
 a liquid epoxy resin being liquid at 20° C. and having at least two epoxy groups in a molecule; 
   a solid epoxy resin being solid at 40° C. and having at least three epoxy groups in a molecule;
 a semisolid epoxy resin being solid at 20° C. and liquid at 40° C. and having at least two epoxy groups in a molecule; 
 an epoxy curing agent; and 
 a filler, 
   wherein a ratio of mass of the liquid epoxy resin to a sum of mass of the solid epoxy resin and mass of the semisolid epoxy resin is about 1:1 to about 1:10, and   wherein a ratio of the mass of the solid epoxy resin to the mass of the semisolid epoxy resin is about 1:0.5 to about 1:2.   
     
     
         3 . A multilayer printed wiring board comprising:
 an inner layer circuit substrate;   a conductor layer having a predetermined circuit pattern; and   a resin insulation layer comprising a dry film according to  claim 1 , the conductor layer and the resin insulation layer being alternately provided on the inner layer circuit substrate, the resin insulation layer having a boundary face which has a microscopic concave-convex roughened surface and to which the conductor layer is bonded.