Method of producing circuit board by additive method, and circuit board and multilayer circuit board obtained by the method

Abstract

The present invention relates to a method of producing a circuit board, comprising: a film-forming step of forming a resin film on the surface of an insulative substrate; a circuit groove-forming step of forming circuit grooves having a depth equal to or greater than the thickness of the resin film on the external surface of the resin film; a catalyst-depositing step of depositing a plating catalyst or the precursor thereof on the surface of the circuit grooves on the insulative substrate and the surface of the resin film; a film-removing step of removing the resin film; and a plating processing step of electroless-plating the insulative substrate after removal of the resin film, wherein a partial reinforcing structure is formed in a region of the circuit groove in the circuit groove-forming step.

1 . A method of producing a circuit board, comprising:
 a film-forming step of forming a resin film on the surface of an insulative substrate;   a circuit groove-forming step of forming circuit grooves having a depth equal to or greater than the thickness of the resin film on the external surface of the resin film;   a catalyst-depositing step of depositing a plating catalyst or the precursor thereof on the surface of the circuit grooves on the insulative substrate and the surface of the resin film;   a film-removing step of removing the resin film; and   a plating processing step of electroless-plating the insulative substrate after removal of the resin film, wherein   a partial reinforcing structure is formed in a region of the circuit groove in the circuit groove-forming step.   
     
     
         2 . The method of producing a circuit board according to  claim 1 , wherein the partial reinforcing structure is an irregular shape formed on predetermined region of the surface of the circuit groove. 
     
     
         3 . The method of producing a circuit board according to  claim 2 , wherein the circuit groove has a circuit pattern consisting of land regions for surface mounting of electronic parts and circuit wiring regions formed integrally with the land regions, and the irregular shape is formed on the groove surface in the land regions. 
     
     
         4 . The method of producing a multilayer circuit board according to  claim 1 , wherein the circuit groove has a circuit pattern consisting of land regions for surface mounting of electronic parts and circuit wiring regions formed integrally with the land regions, and the partial reinforcing structure has a groove shape having the groove depth in the land region larger than that of the circuit wiring region and forming a plated film having thickness in the land region thicker than that of the circuit wiring region. 
     
     
         5 . The method of producing a circuit board according to  claim 1 , wherein the circuit groove has a circuit pattern consisting of land regions for surface mounting of electronic parts and circuit wiring regions formed integrally with the land regions, and the partial reinforcing structure is formed by forming at least one protrusion on the periphery of the groove in the land region. 
     
     
         6 . A method of producing a multilayer circuit board, comprising:
 a film-forming step of forming a resin film on the surface of an insulation layer formed on a circuit board that embeds a conductive rod protruding at predetermined positions of a first electrical circuit;   a circuit groove-forming step of forming circuit grooves having a depth equal to or greater than the thickness of the resin film by laser processing on the external surface of the resin film;   a conductive rod-exposing step of exposing the conductive rod by laser processing from the external surface of the resin film;   a catalyst-depositing step of depositing a plating catalyst or the precursor thereof on the surface of the exposed conductive rod, circuit grooves in the insulation layer, the internal wall of the pores formed in the insulation layer by exposure of the conductive rod, and the surface of the resin film;   a film-removing step of removing the resin film; and   a plating processing step of forming a second electrical circuit by forming an electrolessly plated film in the region where the plating catalyst remains unremoved after the film-removing step and connecting the first and the second electrical circuits to each other with the conductive rod by interlayer connection.   
     
     
         7 . The method of producing a multilayer circuit board according to  claim 6 , wherein the circuit board carrying the embedded conductive rod has a conductive film for heat radiation containing a conductive rod formed as electrically insulated from the first electrical circuit additionally on the surface having the first electrical circuit formed; and the conductive rod in the conductive film for heat radiation are embedded in the insulation layer together with the conductive rod protruding in the first electrical circuit; the conductive rod-exposing step has an additional step of exposing the conductive rod formed protruding in the conductive film for heat radiation by laser processing from the external surface of the resin film; wherein, in the catalyst-depositing step, a plating catalyst or the precursor thereof is deposited additionally on the surface of the conductive rod exposed in the conductive film for heat radiation and the internal wall of the hole formed in the insulative layer by exposure of the conductive rod; and the secondary radiator connected to the first radiator by interlayer connection is formed in the plating processing step. 
     
     
         8 . The method of producing a multilayer circuit board according to  claim 6 , wherein the laser processing for exposure of the conductive rod removes part of the top region of the conductive rod. 
     
     
         9 . The method of producing a multilayer circuit board according to  claim 6 , wherein the resin film is a swellable resin film separated from the insulation layer surface as it is swollen with a particular liquid. 
     
     
         10 . The method of producing a multilayer circuit board according to  claim 6 , wherein the conductive rod-containing circuit board is a substrate obtained by laminating an insulation layer integrally on the surface having a conductive rod previously formed as it protrudes at a predetermined position in the first electrical circuit. 
     
     
         11 . The method of producing a multilayer circuit board according to  claim 6 , wherein the conductive rod-containing circuit board is a substrate obtained by coating a resin solution on the surface having a conductive rod previously formed as it protrudes at a predetermined position in the first electrical circuit and hardening it into an insulation layer. 
     
     
         12 . The method of producing a multilayer circuit board according to  claim 6 , wherein the circuit board that embedded conductive rod is a substrate obtained by forming an insulation layer on the surface of the first electrical circuit, exposing the first electrical circuit by laser processing from the surface of the insulation layer, and forming a conductive rod on the surface of the first electrical circuit by growing a plated film from the exposed first electrical circuit. 
     
     
         13 . The method of producing a multilayer circuit board according to  claim 12 , wherein the step of growing a plated film is a step of growing a plated film by electrolytic plating by using the first electrical circuit exposed after desmear treatment of the laser-processed region as electrode. 
     
     
         14 . The method of producing a multilayer circuit board according to  claim 12 , wherein the step of growing a plated film is a step of growing a plated film by electroless plating by using the first electrical circuit exposed after desmear treatment of the laser-processed region as plating nucleus. 
     
     
         15 . A multilayer circuit board obtained by the production method according to  claim 7 , comprising heat radiation structures penetrating the internal layers. 
     
     
         16 . A method of producing a multilayer circuit board, comprising:
 an insulation layer-forming step of forming an insulation layer on the surface of a substrate carrying a first electrical circuit formed thereon;   a film-forming step of forming a resin film on the insulation layer surface;   a circuit groove-forming step of forming circuit grooves having a depth equal to or greater than the thickness of the resin film by laser processing on the external surface of the resin film;   a catalyst-depositing step of depositing a plating catalyst or the precursor thereof both on the surface of the circuit grooves formed on the insulation layer and the surface of the resin film;   a film-removing step of removing the resin film;   a plating processing step of forming a second electrical circuit by forming an electrolessly plated film in the region where the plating catalyst remains unremoved after the film-removing step;   a laser processing step of exposing the first electrical circuit by laser processing in a particular region of the second electrical circuit; and   an interlayer connection-forming step of connecting the first and second electrical circuits to each other by interlayer connection by growing a plated film on the surface of the exposed first electrical circuit.   
     
     
         17 . The method of producing a multilayer circuit board according to  claim 16 , wherein the interlayer connection-forming step is a step of growing the plated film by electrolytic plating by using the first electrical circuit exposed after desmear treatment of the laser-processed region, as electrode. 
     
     
         18 . The method of producing a multilayer circuit board according to  claim 16 , wherein the interlayer connection-forming step is a step of growing the plated film by electroless plating by using the surface of the first electrical circuit exposed after desmear treatment of the laser-processed region, as plating nucleus. 
     
     
         19 . The method of producing a multilayer circuit board according to  claim 16 ,
 wherein the substrate has a first conductive film for heat radiation formed as electrically insulated from the first electrical circuit additionally on the surface having the first electrical circuit formed;   and the circuit groove-forming step has an additional step of forming a second conductive film forming groove for heat radiation isolated from the circuit groove equal to or greater than the thickness of the resin film by laser processing from above the first conductive film;   and in the catalyst-depositing step, depositing a plating catalyst or the precursor thereof additionally on the surface of the second conductive film forming groove;   and in a plating processing step, forming a second conductive film for heat radiation by forming an electrolessly plated film on the surface of the second conductive film forming groove;   and the laser processing step exposing the first electrical circuit has an additional step of exposing the first conductive film for heat radiation by laser processing from above the first conductive film;   and in the interlayer connection-forming step, connecting the first and the second conductive films to each other by interlayer connection by growing a plated film on the surface of the exposed first conductive film, additionally.