Method of producing base plate for circuit board, base plate for circuit board, and circuit board using the base plate

Abstract

First, a melt of Al or a melt of an Al alloy containing Si is injected in a die filled with SiC powder and cast to form a plate member made of an Al/SiC composite. Next, an Al foil member made of an Al—Mg-based alloy is joined with the surface of the plate member through hot pressing. As a result, part of the Al foil member enters casting blowholes on the surface of the plate member to fill the casting blowholes. In addition, an Al—Mg-based alloy layer is formed on the surface of the plate member. Thus, a base plate having a nearly flat surface is produced.

1 . A method of producing a base plate for a circuit board, comprising the steps of: 
 casting a plate member made of an Al/SiC composite; and    joining through heating an Al foil member with a front surface of the cast plate member.    
   
   
       2 . A method of producing a base plate for a circuit board according to  claim 1 , wherein the Al foil member is joined with the front surface of the plate member through hot pressing.  
   
   
       3 . A method of producing a base plate for a circuit board according to  claim 1 , wherein the Al foil member is joined with the front surface of the plate member through rolling.  
   
   
       4 . A method of producing a base plate for a circuit board according to  claim 1 , wherein the Al foil member is formed of one of an Al—Mg-based alloy, an Al—Li-based alloy, and an Al—Ti-based alloy.  
   
   
       5 . A method of producing a base plate for a circuit board according to  claim 1 , wherein: 
 the Al foil member has a higher melting point than a melting point of the Al/SiC composite forming the plate member; and    the Al foil member is heated to a temperature near the melting point of the Al/SiC composite forming the plate member to be joined with the front surface of the plate member.    
   
   
       6 . A method of producing a base plate for a circuit board according to  claim 1 , wherein: 
 the Al foil member has a lower melting point than a melting point of the Al/SiC composite forming the plate member; and    the Al foil member is heated to a temperature near its melting point to be joined with the front surface of the plate member.    
   
   
       7 . A method of producing a base plate for a circuit board according to  claim 1 , wherein the surface of the Al foil member is subjected to a surface-roughening treatment after the Al foil member is joined with the front surface of the plate member.  
   
   
       8 . A method of producing a base plate for a circuit board according to  claim 1 , wherein the plate member is made of an Al/SiC composite that is cast by injecting a melt of Al or a melt of an Al alloy containing Si in a die filled with SiC powder.  
   
   
       9 . A method of producing a base plate for a circuit board according to  claim 1 , wherein an Al heat sink member is joined through heating with a rear surface of the plate member simultaneously with the joining through heating of the Al foil member with the front surface of the plate member.  
   
   
       10 . A method of producing a base plate for a circuit board according to  claim 9 , wherein the Al heat sink member is formed of one of an Al—Mg-based alloy, an Al—Li-based alloy, and an Al—Ti-based alloy.  
   
   
       11 . A method of producing a base plate for a circuit board according to  claim 9 , wherein: 
 the Al heat sink member is formed of pure Al; and    the Al heat sink member is joined with the rear surface of the plate member via an insert member formed of one of an Al—Mg-based alloy, an Al—Li-based alloy, and an Al—Ti-based alloy.    
   
   
       12 . A method of producing a base plate for a circuit board according to  claim 9 , wherein the Al heat sink member is formed in advance into a shape of a heat sink.  
   
   
       13 . A method of producing a base plate for a circuit board according to  claim 9 , wherein the Al heat sink member is formed into a shape of a heat sink after the Al heat sink member is joined with the rear surface of the plate member.