Pb-free solder-connected structure

摘要

Provided are a bonded structure by a lead-free solder and an electronic article comprising the bonded structure. The bonded structure has a stable bonding interface with respect to a change in process of time, an enough strength and resistance to occurrence of whiskers while keeping good wettability of the solder. In the bonded structure, a lead-free Sn—Ag—Bi alloy solder is applied to an electrode through an Sn—Bi alloy layer. The Sn—Bi alloy, preferably, comprises 1 to 20 wt % Bi in order to obtain good wettability of the solder. In order to obtain desirable bonding characteristics having higher reliability in the invention, a copper layer is provided under the Sn—Bi alloy layer thereby obtaining an enough bonding strength.

主权项

1. A structure to be mounted on a substrate via a Pb-free solder, comprising:
an LSI; a lead; and a Bi-containing layer formed on the lead and constituted by an alloy consisting essentially of Sn and Bi, wherein a contained amount of Bi in the alloy is greater than or equal to 1 wt %, and less than or equal to 5 wt %; and wherein the Bi-containing layer is a layer separate from the Pb-free solder.