Wiring Board for Light-Emitting Element

Abstract

A wiring board for light-emitting element, comprising a ceramic insulating substrate, and a conductor layer formed on the surface or in the inside of the insulating substrate, and having a mounting region mounting a light-emitting element on one surface of the insulating substrate; wherein the insulating substrate is provided with a heat-conducting pole-like conductor having a thermal conductivity higher than that of said insulating substrate; and the heat-conducting pole-like conductor is extending through the insulating substrate in the direction of thickness thereof from the light-emitting element mounting region of the insulating substrate, and is formed by the co-firing with the insulating substrate. The wiring board is produced inexpensively by co-firing, features excellent heat-radiating performance, is capable of quickly radiating the heat from the light-emitting element when the light-emitting element is mounted, and effectively prevents a decrease in the brightness of the light-emitting element caused by the heat.

1 . A wiring board for light-emitting element, comprising a ceramic insulating substrate, and a conductor layer formed on the surface or in the inside of said insulating substrate, and having a mounting region mounting a light-emitting element on one surface of said insulating substrate; wherein 
 said insulating substrate is provided with a heat-conducting pole-like conductor having a thermal conductivity higher than that of said insulating substrate; and    said heat-conducting pole-like conductor is extending through said insulating substrate in the direction of thickness thereof from the light-emitting element mounting region of said insulating substrate, and is formed by co-firing with said insulating substrate.    
   
   
       2 . A wiring board for light-emitting element according to  claim 1 , wherein said insulating substrate is formed by firing at a temperature of higher than 1050° C.  
   
   
       3 . A wiring board for light-emitting element according to  claim 1 , wherein said insulating substrate is formed by firing at a temperature of not higher than 1050° C.  
   
   
       4 . A wiring board for light-emitting element according to  claim 1 , wherein the surface of said insulating substrate on the side of the light-emitting element mounting region has a total reflection factor of not lower than 70%.  
   
   
       5 . A wiring board for light-emitting element according to  claim 1 , wherein said heat-conducting pole-like conductor has a plane sectional area greater than that of the mounting area for mounting the light-emitting element.  
   
   
       6 . A wiring board for light-emitting element according to  claim 1 , wherein the boundary portion between the end surface of said heat-conducting pole-like conductor and the surface of said insulating substrate, and the vicinity thereof, are covered with a boundary protection layer formed by at least one of those selected from the group consisting of a metal, ceramics and a resin.  
   
   
       7 . A wiring board for light-emitting element according to  claim 1 , wherein the end surface of said heat-conducting pole-like conductor on the side of the mounting region and the peripheral edges thereof are covered with a covering layer containing a metal or a resin.  
   
   
       8 . A wiring board for light-emitting element according to  claim 1 , wherein the end surface of said heat-conducting pole-like conductor on the opposite side to the mounting region and the peripheral edges thereof are covered with a covering layer containing at least one of those selected from the group consisting of a metal, ceramics and a resin.  
   
   
       9 . A wiring board for light-emitting element according to  claim 1 , wherein said heat-conducting pole-like conductor has a thermal conductivity of not smaller than 80 W/m·K.  
   
   
       10 . A wiring board for light-emitting element according to  claim 1 , wherein said heat-conducting pole-like conductor is formed by using a metal material and a ceramic material.  
   
   
       11 . A wiring board for light-emitting element according to  claim 1 , wherein said heat-conducting pole-like conductor is incorporated in a portion of electric circuit.  
   
   
       12 . A wiring board for light-emitting element according to  claim 1 , wherein said heat-conducting pole-like conductor is formed by using a plurality of layers having different coefficients of thermal expansion or different thermal conductivities.  
   
   
       13 . A wiring board for light-emitting element according to  claim 1 , wherein the side surface of said heat-conducting pole-like conductor is forming a tilted surface.  
   
   
       14 . A wiring board for light-emitting element according to  claim 1 , wherein a step is formed on a side surface of said heat-conducting pole-like conductor.  
   
   
       15 . A wiring board for light-emitting element according to  claim 14 , wherein said insulating substrate has a laminated-layer structure of a plurality of insulating layers, said step formed on the side surface of said heat-conducting pole-like conductor is positioned on the interface between the neighboring insulating layers, and a conducting layer is extending from said step along the interface between said insulating layers.  
   
   
       16 . A wiring board for light-emitting element according to  claim 15 , wherein said conducting layer is extending from the edge of said step over a length of not smaller than 50 μm.  
   
   
       17 . A wiring board for light-emitting element according to  claim 1 , wherein a frame is formed on said insulating substrate surrounding said light-emitting element mounting region so as to protect the light-emitting element that is mounted.  
   
   
       18 . A wiring board for light-emitting element according to  claim 17 , wherein the inner wall surface of said frame has a total reflection factor of not smaller than 70%.  
   
   
       19 . A wiring board for light-emitting element according to  claim 17 , wherein the inner wall surface of said frame has such a shape that the inner diameter at the upper end is greater than the inner diameter at the lower end, and is forming a curved surface that is swelling toward the side of said mounting region.  
   
   
       20 . A wiring board for light-emitting element according to  claim 17 , wherein on the inner wall surface of said frame, there is provided a light-reflecting layer comprising a gold-plated layer and a silver-plated layer formed thereon.  
   
   
       21 . A light-emitting device mounting a light-emitting element on the mounting region of a wiring board for light-emitting element of  claim 1.