Pb-free solder-connected structure and electronic device

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...

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Bibliographic Details
Main Authors Shimokawa, Hanae, Soga, Tasao, Okudaira, Hiroaki, Ishida, Toshiharu, Nakatsuka, Tetsuya, Inaba, Yoshiharu, Nishimura, Asao
Format Patent
LanguageEnglish
Published 01.11.2005
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Summary: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.