Solder alloy, electronic board using the solder alloy, and method of manufacturing the electronic board

Abstract

A solder alloy for flow soldering is disclosed that includes 3.0 wt % to 14.0 wt % Zn, 0.003 wt % to 0.05 wt % Al, and the balance of Sn.

1 . A solder alloy for flow soldering, comprising:
 3.0 wt % to 14.0 wt % Zn;   0.003 wt % to 0.05 wt % Al; and   the balance of Sn.   
     
     
         2 . The solder alloy for flow soldering as claimed in  claim 1 , wherein Al is more than 0.008 wt %. 
     
     
         3 . The solder alloy for flow soldering as claimed in  claim 1 , wherein Zn is 7.0 wt % to 11.0 wt %. 
     
     
         4 . The solder alloy for flow soldering as claimed in  claim 3 , wherein:
 Zn is less than or equal to 9.0 wt %; and   Al is more than 0.003 wt %.   
     
     
         5 . An electronic board, comprising:
 an electronic component; and   a circuit board,   wherein the electronic component and the circuit board have a soldered joint formed of the solder alloy as set forth in  claim 1 .   
     
     
         6 . A method of manufacturing an electronic board, comprising:
 a step of attaching an electronic component to a circuit board; and   a joining step of melting a solder alloy formed of a Sn—Zn—Al alloy and soldering the electronic component to the circuit board by brining the molten solder alloy into contact with the circuit board.   
     
     
         7 . The method as claimed in  claim 6 , wherein the joining step supplies the molten solder alloy with a material containing Al in accordance with an amount of oxidized Al in the molten solder alloy. 
     
     
         8 . The method as claimed in  claim 7 , wherein the material containing Al is a solid Al material. 
     
     
         9 . The method as claimed in  claim 7 , wherein the material containing Al is one of a solid Zn—Al alloy and a molten Zn—Al alloy. 
     
     
         10 . The method as claimed in  claim 6 , wherein the solder alloy comprises:
 3.0 wt % to 14.0 wt % Zn;   0.003 wt % to 0.05 wt % Al; and   the balance of Sn.