Solder joint structure and method for soldering electronic components

Abstract

A method for soldering an electronic component is provided. A first solder land containing copper and a second solder land are formed on a surface of a circuit board. A first solder section composed of a Sn—Ag—Cu solder material is formed on each of the first and the second solder lands, and a terminal of an electronic component chip is mounted on the first solder land. The first solder land and the terminal are fusion-bonded. A second solder section composed of a Sn—Zn solder material is formed on the first solder section disposed on the second solder land. A lead terminal of another electronic component is inserted into a terminal hole formed near the second solder land; and the second solder section and the lead terminal are heated at a temperature lower than the temperature in step (d) to connect the lead terminal to the second solder section by fusion bonding.

1 . A solder joint structure comprising: 
 a patterned conductor containing copper;    a solder base section comprising a Sn—Ag—Cu solder material; and    a solder joint section comprising a Sn—Zn solder material, the wherein the solder joint section connects with a terminal of an electronic component by fusion bonding.    
   
   
       2 . The solder joint structure according to  claim 1 , wherein the Sn—Ag—Cu solder material contains at least one additive selected from the group consisting of antimony, nickel, phosphorus, germanium, and gallium.  
   
   
       3 . A solder joint structure comprising: 
 a patterned conductor containing copper;    a solder base section comprising a Sn—Ag solder material containing at least one additive selected from the group consisting of antimony, nickel, phosphorus, germanium, gallium, aluminum, cobalt, chromium, iron, manganese, palladium, and titanium; and    a solder joint section comprising a Sn—Zn solder material, the solder joint section being disposed on the solder base section,    wherein the solder joint section connects with a terminal of an electronic component by fusion bonding.    
   
   
       4 - 6 . (canceled)