焊料接合层具有第一晶体部分（21）分散在基体（22）中沉淀结构之间的多个细粒状的第二晶体部分晶界。 第一晶体部分（21）是由多个含有锡和锑中的预定比率的Sn晶粒。 第二晶体部分（22）具有含有以预定比例的Ag原子相对于Sn原子或以规定的比例含有铜原子的第二部分相对于Sn原子的第一部分或由两者的， 是的。 此外，焊料结合层，所述第三可具有结晶部（23）是含有Sb的原子在相对于Sn原子的预定比率的晶粒。 因此，允许在低的熔点的焊料接头，它具有基本上均匀的金属结构，它能够形成可靠的钎焊接合部的层。

The solder bonding layer has a first crystal part (21) a second crystal portion grain boundaries of a plurality of fine granular between (22) was precipitated structure dispersed in a matrix. The first crystal part (21) is a plurality of Sn crystal grains containing tin and antimony in a predetermined ratio. The second crystal part (22) has a first portion containing Ag atoms at a predetermined ratio relative to Sn atom, or a second part including Cu atoms at a predetermined ratio relative to Sn atom, or composed of both, It is. Further, the solder bonding layer, the third may have a crystal part (23) is a crystal grain containing Sb atoms at a predetermined ratio relative to Sn atom. Thereby, it possible to solder bonding at a low melting point, have a substantially uniform metal structure, it is possible to form a highly reliable solder joint layer.