REFLOW SOLDERING METHOD EMPLOYING Pb-FREE SOLDER ALLOY, REFLOW SOLDERING METHOD, MIXED MOUNTING METHOD AND MIXED MOUNTED STRUCTURE

PROBLEM TO BE SOLVED: To provide a mixed mounting method employing a Pb-free solder alloy in which reflow soldering of a low heat resistant electronic component, e.g. an FPGA, is realized while sustaining the reliability of solder joint strength at the time of reflow soldering. SOLUTION: The mixed mounting method employing a Pb-free solder alloy comprises a step for reflow soldering a surface mounting component 2 at least onto the upper surface of a circuit board 1 using Pb-free reflow solder paste composed of an Sn-(1-4)Ag-(0-1)Cu-(7-10)In (unit: mass%) based alloy, a step for inserting the lead or terminal of an inserted mounting component 5 into a through hole made through the circuit board 1 from the upper surface side, a flux coating step, a preheating step, and a step for reflow soldering the lead or terminal of the inserted mounting component to the circuit board 1 by applying a jet stream 3 of Pb-free solder to the lower surface of the circuit board 1 preheated in the preheating process. COPYRIGHT: (C)2005,JPO&NCIPI