Showa Denko K.K. (SDK) has started full-scale marketing of its ST60-HSM aluminum alloy board, which has high heat conductivity and high strength, for use as on-board bus bar.

Bus bars are used to conduct electricity, and many bus bars are made of copper. A bus bar can conduct more electric current than wire; thus, a bus bar is used to conduct large current.

ST60 is an aluminum alloy board developed by SDK in 2001, and has as much heat conductivity as pure aluminum and as much strength as 5052 aluminum alloy—a typical structural material. ST60-HSM has relatively high strength and plasticity among ST60 series aluminum alloys, has as much tensile strength as 6061 aluminum alloy, and is used for internal chassis of smartphones and tablets and the metal base of their cases. HSM is an abbreviation of High Strength Metal.

In 2021, SDK started to provide several automotive parts manufacturers with samples of ST60-HSM aluminum-alloy boards to be used as on-board bus bars.

The car industry has been accelerating its shift to electric cars including hybrid cars, plug-in hybrid cars and EVs. In addition, the car industry is now required to reduce vehicle weight where it can in order to improve fuel efficiency and increase range.

Therefore, the industry is aggressively promoting shift from copper-based equipment to lighter-weight aluminum-alloy-based equipment in various components including wiring harnesses and bus bars to connect on-board motors with converters and inverters with generators.

SDK’s ST60-HSM is an aluminum alloy board that has high heat conductivity, high strength and high electric conductivity, and also has high fatigue strength and high heat-resisting property required for on-board bus bars. An aluminum bus bar made of ST60-HSM is 43% lighter than a comparable conventional copper bus bar and also contributes to cost reduction because the new aluminum bus bar is priced lower than a conventional copper bus bar.