Printed wiring board and method for manufacturing printed wiring board

Abstract

A printed wiring board includes a core substrate having a penetrating hole penetrating through the core substrate and having a first insulation layer, a second insulation layer and an insulative substrate interposed between the first and second layers, a first circuit formed on a surface of the core, a second circuit formed on opposite surface of the core, and a through-hole conductor formed in the penetrating hole of the core and connecting the first and second circuits. The penetrating hole has first and second opening portions, the first opening portion becomes thinner from the first surface toward the second surface, the second opening portion becomes thinner from the second surface toward the first surface, and the first and second insulation layers are comprised of resin materials easier to be processed by laser than resin material of the insulative substrate under same conditions of the laser.

1 - 14 . (canceled) 
     
     
         15 . A method for manufacturing a printed wiring board, comprising:
 preparing a core substrate having a first surface and a second surface on an opposite side of the first surface and comprising a first insulation layer, a second insulation layer and an insulative substrate interposed between the first insulation layer and the second insulation layer;   forming a penetrating hole having a first opening portion and a second opening portion in the core substrate such that the first opening portion becomes thinner from the first surface of the core substrate toward the second surface and that the second opening portion becomes thinner from the second surface of the core substrate toward the first surface;   forming a first circuit on the first surface of the core substrate;   forming a second circuit on the second surface of the core substrate; and   forming a plated film in the penetrating hole such that a through-hole conductor connecting the first circuit and the second circuit is formed,   wherein the first insulation layer comprises a resin material which is easier to be processed by a laser than a resin material of the insulative substrate when the first opening portion is formed under same conditions of the laser for the first insulation layer and the insulative substrate, and the second insulation layer comprises a resin material which is easier to be processed by a laser than the material of the insulative substrate when the second opening portion is formed under same conditions of the laser for the second insulation layer and the insulative substrate.   
     
     
         16 . The method for manufacturing a printed wiring board according to  claim 15 , wherein the preparing of the core substrate comprises providing the insulative substrate having a main surface and a secondary surface on an opposite side of the main surface, laminating the first insulation layer such that the first insulation layer faces the main surface of the insulative substrate, and laminating the second insulation layer such that the second insulation layer faces the secondary surface of the insulative substrate. 
     
     
         17 . The method for manufacturing a printed wiring board according to  claim 15 , wherein the forming of the penetrating hole comprises forming the first opening portion by irradiating a laser on the first surface of the core substrate and forming the second opening portion by irradiating a laser on the second surface of the core substrate. 
     
     
         18 . The method for manufacturing a printed wiring board according to  claim 15 , wherein the insulative substrate includes a reinforcing material. 
     
     
         19 . The method for manufacturing a printed wiring board according to  claim 15 , wherein the first insulation layer includes an inorganic filler, and the second insulation layer includes an inorganic filler. 
     
     
         20 . The method for manufacturing a printed wiring board according to  claim 15 , wherein the insulative substrate includes a reinforcing material, the first insulation layer includes an inorganic filler, the second insulation layer includes an inorganic filler, and the first insulation layer and the second insulation layer do not include a reinforcing material. 
     
     
         21 . The method for manufacturing a printed wiring board according to  claim 15 , wherein the first opening portion is formed by irradiating a CO 2  gas laser on the first surface of the core substrate, and the second opening portion is formed by irradiating a CO 2  gas laser on the second surface of the core substrate. 
     
     
         22 . The method for manufacturing a printed wiring board according to  claim 16 , wherein the insulative substrate includes a reinforcing material. 
     
     
         23 . The method for manufacturing a printed wiring board according to  claim 22 , wherein the first insulation layer includes an inorganic filler, and the second insulation layer includes an inorganic filler. 
     
     
         24 . The method for manufacturing a printed wiring board according to  claim 23 , wherein the first insulation layer and the second insulation layer do not include a reinforcing material. 
     
     
         25 . The method for manufacturing a printed wiring board according to  claim 22 , wherein the reinforcing material is a glass cloth. 
     
     
         26 . The method for manufacturing a printed wiring board according to  claim 15 , wherein a straight line passing through the gravity center of the first opening and perpendicular to the first surface of the core substrate is not aligned with a straight line passing through the gravity center of the second opening and perpendicular to the first surface of the core substrate. 
     
     
         27 . The method for manufacturing a printed wiring board according to  claim 15 , wherein the forming of the plated film in the penetrating hole comprises filling the penetrating hole with a plating material such that the through-hole conductor made of the plated film filling the penetrating hole is formed. 
     
     
         28 . The method for manufacturing a printed wiring board according to  claim 22 , wherein the reinforcing material is an aramid fiber material. 
     
     
         29 . The method for manufacturing a printed wiring board according to  claim 15 , wherein the first insulation layer and the second insulation layer do not include a reinforcing material. 
     
     
         30 . The method for manufacturing a printed wiring board according to  claim 15 , wherein the first insulation layer includes an inorganic filler comprising at least one of silica and alumina, and the second insulation layer includes an inorganic filler comprising at least one of silica and alumina. 
     
     
         31 . The method for manufacturing a printed wiring board according to  claim 15 , wherein the first opening portion is formed by irradiating a CO 2  gas laser on the first surface of the core substrate, and the second opening portion is formed by irradiating a CO 2  gas laser on the second surface of the core substrate, and a straight line passing through the gravity center of the first opening and perpendicular to the first surface of the core substrate is not aligned with a straight line passing through the gravity center of the second opening and perpendicular to the first surface of the core substrate. 
     
     
         32 . The method for manufacturing a printed wiring board according to  claim 15 , wherein the forming of the penetrating hole comprises forming the first opening portion by irradiating a laser on the first surface of the core substrate and forming the second opening portion by irradiating a laser on the second surface of the core substrate, and a straight line passing through the gravity center of the first opening and perpendicular to the first surface of the core substrate is not aligned with a straight line passing through the gravity center of the second opening and perpendicular to the first surface of the core substrate.