Soldering alloy, soldering paste, preform solder, soldering ball, wire solder, resin flux cored solder, solder joint, electronic circuit board, and multi-layer electronic circuit board

Abstract

A soldering alloy includes an alloy composition consisting of 13-22 mass % of In, 0.5-2.8 mass % of Ag, 0.5-5.0 mass % of Bi, 0.002-0.05 mass % of Ni, and a balance Sn. A soldering alloy, a soldering paste, a preform solder, a soldering ball, a wire solder, a resin flux cored solder and a solder joint, each of which is composed of the soldering alloy. An electronic circuit board and a multi-layer electronic circuit board joined by using the solder joint.

1 . A soldering alloy comprising an alloy composition consisting of 13-22 mass % of In, 0.5-2.8 mass % of Ag, 0.5-5.0 mass % of Bi, 0.002-0.05 mass % of Ni, and a balance Sn. 
     
     
         2 . The soldering alloy according to  claim 1 , wherein the alloy composition further contains at least one selected from P, Ge and Ga in total of 0.09 mass % or less. 
     
     
         3 . The soldering alloy according to  claim 1 , wherein the alloy composition further contains 0.005-0.1 mass % of Sb. 
     
     
         4 . The soldering alloy according to  claim 1 , wherein the content of In is 15-20%. 
     
     
         5 . The soldering alloy according to  claim 4 , wherein an upper limit of the content of In is 17%. 
     
     
         6 . The soldering alloy according to  claim 1 , wherein the content of Ag is 1.0-2.5%. 
     
     
         7 . The soldering alloy according to  claim 1 , wherein the content of Bi is 1.0-2.5%. 
     
     
         8 . The soldering alloy according to  claim 1 , wherein the content of Ni is 0.003-0.04%. 
     
     
         9 . The soldering alloy according too  claim 1 , wherein the content of In, Ag, Bi, and Ni satisfies the following equation (1),
   0.9≤(In×Ni)×(Ag+Bi)≤3.4  (1)
   wherein, in the relationship (1), In, Ni, Ag, and Bi represent each content of the respective elements.   
     
     
         10 . The soldering alloy according to  claim 1 , wherein a solidus temperature is 160° C. or more and a liquidus temperature is 210° C. or less. 
     
     
         11 . The soldering alloy according to  claim 10 , wherein the solidus temperature is 165° C. or higher and the liquidus temperature is 200° C. or lower. 
     
     
         12 . A soldering paste consisting of the soldering alloy according to  claim 1 . 
     
     
         13 . A preform solder consisting of the soldering alloy according to  claim 1 . 
     
     
         14 . A soldering ball consisting of the soldering alloy according to  claim 1 . 
     
     
         15 . A wire solder consisting of the soldering alloy according to  claim 1 . 
     
     
         16 . A resin flux cored solder consisting of the soldering alloy according to  claim 1 . 
     
     
         17 . A solder joint consisting of a soldering alloy comprising an alloy composition consisting of 13-22 mass % of In, 0.5-2.8 mass % of Ag, 0.5-5.0 mass % of Bi, 0.002-0.05 mass % of Ni, and a balance Sn, wherein the solder joint does not include another soldering alloy other than the soldering alloy comprising the alloy composition. 
     
     
         18 . An electronic circuit board comprising an electronic part joined by using the solder joint according to  claim 17 . 
     
     
         19 . The electronic circuit board according to  claim 18 , further comprising a high thermal resistance electronic part which has a higher thermal resistance temperature than the electronic part,
 wherein the high thermal resistance electronic part is joined by using another alloy having a melting point higher than the liquidus temperature of the soldering alloy included in the solder joint.   
     
     
         20 . The electronic circuit board according to  claim 18 , further comprising a low thermal resistance electronic part which has a lower heat resistance temperature than the electronic part,
 wherein the low thermal resistance electronic part is joined by using another solder joint including another soldering alloy having a melting point lower than the solidus temperature of the soldering alloy.   
     
     
         21 . A multi-layer electronic circuit board, comprising:
 a first board including an electronic part joined by using a solder joint consisting of a soldering alloy comprising an alloy composition consisting of 13-22 mass % of In, 0.5-2.8 mass % of Ag, 0.5-5.0 mass % of Bi, 0.002-0.05 mass % of Ni, and a balance Sn, wherein the solder joint does not include another soldering alloy other than the soldering alloy; and   a second board including a high thermal resistance electronic part which is laminated on the first board and has a higher thermal resistance temperature than the electronic part,   wherein the high thermal resistance electronic part and the second board are joined by using another solder joint including another soldering alloy having a melting point higher than the liquidus temperature of the soldering alloy included in the solder joint.   
     
     
         22 . A multi-layer electronic circuit board, comprising:
 a first board including an electronic part joined by using the solder joint according to  claim 17 ; and   a second board including a low thermal resistance electronic part which is laminated on the first board and has a lower thermal resistance temperature than the electronic part,   wherein the low thermal resistance electronic part and the second board are joined by using another solder joint including another soldering alloy having a melting point lower than the solidus temperature of the soldering alloy included in the solder joint.