Kuniteru Mihara, Tatsuhiko Eguchi, Takashi Yamamoto and Akihiro Kanamori
Abstract
As electronic equipment such as mobile phones become more compact, higher in mounting density and lower in profile in recent years, connector materials for these equipment are required to be higher in strength and better in bending workability. In response to such requirements, Furukawa Electric has developed F5218 and F5248 alloys, new versions of phosphor bronze for springs with smaller grain size, achieving improved strength and bending workability 1). In this work, the following conclusions were reached: the grain size and strength in recrystallized structures can be described by the Hall-Petch relationship; the strength and bending workability improve as grain size is reduced; irrespective of their small grain size, degradation in the stress relaxation is suppressed due to Fe-(Ni)-P precipitates; and their grain growth rates are lower than those of C5210 and C5240 due to the contribution of P precipitates that suppress the growth.
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