The invention provides a solder alloy of Sn, Sb, Ag and Cu, wherein the Sb is about 1.0-3.0 wt %; the Ag is about 1.0 wt % or more and about 2.0 wt % or less; the Cu is about 1.0 wt % or less; and the remainder is Sn. The solder alloy has a comparatively low Young's modulus and sufficient tensile characteristics. Therefore, it resists peeling from the bonded electrode, etc., even though a heat stress is added. Also, a solder which has an excellent solderbility to metal phases such as Cu and Ni can be provided. Therefore, a solder alloy excellent in thermal shock resistance can be provided. The solder alloy may be used for soldering the inside of an electronic component.
An electronic component having thermal shock resistance and high reliability includes an element having a functional part and a first frame-shaped electrode surrounding the functional part, a substrate including a second frame-shaped electrode, and a solder sealing frame provided on the surface of at least one of the first frame-shaped electrode and the second frame-shaped electrode. In the electronic component device, the element and the substrate are bonded with the solder sealing frame, and the functional part provided on the element is hermetically sealed in a space formed between the element and the substrate. When the difference in expansion in the x direction between the element and the substrate is represented by Q.sub.x and the difference in expansion in the y direction between the element and the substrate is represented by Q.sub.y, then in each of the first frame-shaped electrode, the second frame-shaped electrode, and the solder sealing frame, a width of a strip-shaped portion extending in the direction having the larger difference in expansion is smaller than a width of a strip-shaped portion extending in the direction having the smaller difference in expansion.
A solder composition and associated method of formation. The solder composition comprises a substantially lead-free alloy that includes tin (Sn), silver (Ag), and copper. The tin has a weight percent concentration in the alloy of at least about 90%. The silver has a weight percent concentration X in the alloy. X is sufficiently small that formation of Ag.sub.3 Sn plates is substantially suppressed when the alloy in a liquefied state is being solidified by being cooled to a lower temperature at which the solid Sn phase is nucleated. This lower temperature corresponds to an undercooling .delta.T relative to the eutectic melting temperature of the alloy. Alternatively, X may be about 4.0% or less, wherein the liquefied alloy is cooled at a cooling rate that is high enough to substantially suppress Ag.sub.3 Sn plate formation in the alloy. The copper has a weight percent concentration in the alloy not exceeding about 1.5%.
