Furukawa Electric Develops Oxygen-free Copper Strips with Superior Heat-resisting Properties
- World-leading heat-resisting properties realized through proprietary structure control -

April 3, 2017

Furukawa Electric Co., Ltd. has successfully developed "GOFC" oxygen-free copper strips. This material for use in power module substrates and surrounding components offers world-leading heat resistance performance. Furukawa Electric has already begun shipping samples, and plans to reach a production output of 50 tons/month in the 2020 FY.


Power modules provide a range of functions including automobile motor control and power conversion. Manufacturers continue to release power modules with higher output and performance as technological innovations are brought to next generation automobiles (such as hybrids and electric automobiles) and renewable energy (such as wind and solar power generation).
Power module substrates and surrounding components are subject to rapidly increasing thermal and electric loads. Oxygen-free copper strips (C1020R)(note 1) are therefore used as materials for these parts in order to provide high conductivity, thermal conductivity, and heat dissipation.
Feedback from customers has suggested that using standard oxygen-free copper strips (C1020R) can cause grain coarsening to occur during the heat-treating process when manufacturing power modules, resulting in a variety of difficulties when bonding during subsequent processes or when joining power modules with other parts. Customers have therefore called for the development of oxygen-free copper strips that do not cause grain coarsening.

(note 1)JIS H 3100:
Copper and copper alloy sheets and strips


Furukawa Electric has developed technology to mass produce "GOFC" (Grain Growth Control Oxygen-free Copper) oxygen-free copper strips. Based on standard oxygen-free copper strips (C1020R), Furukawa Electric applied proprietary structure control technology without altering compositional standards to make it more difficult for grain coarsening to occur.
While grain coarsening occurs suddenly in standard oxygen-free copper strips when heat-treated at a temperature of 500°C or higher, this new product is capable of keeping crystal grain small at temperatures up to 800°C (Fig. 1, Fig. 2). Furukawa Electric will continue to enhance its product lineup, in order to offer strip products with a thickness of 0.3 to 1.0 mm.

Furukawa Electric has already begun shipping samples for insulated substrate joint material applications, and will expand sales of "GOFC" to a wide range of users in order to help customers struggling with deformation and changes in appearance caused by high temperatures in power modules and other parts, and to contribute to increasing power module functionality.

Comparison of crystal grain growth in newly developed product and conventional material

Fig. 1 Microscopic photo of structure when kept at 800pr for one hour (in argon atmosphere)
(1/2H quality classification prior to heat treatment for both)

Fig. 2 Grain size when kept at each temperature for one hour

About Furukawa Electric Group

Furukawa Electric (TSE; 5801, ISIN; JP3827200001) Group started business in 1884, when its copper-smelting facility and wire manufacturing factory was established. Since then Furukawa Electric has become pioneers in the latest technologies by addressing diverse technological issues. Furukawa Electric has released products in a number of areas, including telecommunications, electronics, automobiles, and construction, with the three types of materials it works with at their core, namely, optics, plastics, and metals. Many of these products have attained the top global market share, and all of its products have contributed to society in numerous business areas. Furukawa Electric reported consolidated revenues of JPY 874.9 billion (approximately USD 8.0B) for the fiscal year ended March 31, 2016.