Image Number 6 for United States Patent #8411455.
A mounting structure 1 in which an electronic component 5 is surface-mounted with solder 4 to a wiring substrate 2 is disclosed. The solder is Sn--Ag--Bi--In-based solder containing 0.1% by weight or more and 5% by weight or less of Bi, and more than 3% by weight and less than 9% by weight of In, with the balance being made up of Sn, Ag and unavoidable impurities. The wiring substrate has a coefficient of linear expansion of 13 ppm/K or less in all directions. Thus, it is possible to realize a mounting structure using lead-free solder and for which the occurrence of cracks in a solder joint portion due to a 1000-cycle thermal shock test from -40 to 150.degree. C. has been suppressed.