Furukawa Electric to Increase Production of “GOFC” Oxygen-free Copper Strips with Excellent Thermal Resistance
- Providing customers with value through excellent conductivity and thermal resistance -

September 20, 2018

Furukawa Electric Co., Ltd. has established a system to increase production of “GOFC,” an oxygen-free copper strip (C1020) with improved thermal resistance.
The product was successfully developed as a material for power module substrates and surrounding parts in automobiles, and subsequently released to market in April of last year (2017). Furukawa Electric will continue to meet the demand for increased production while satisfying customers’ strict long-term reliability testing standards and having the product certified for use as a material.


As more plug-in hybrid vehicles and electric vehicles are released, the use of drive motors continues to spread and the demand for power modules continues to rise. The number of power semi-conductor devices installed in such vehicles to convert and control power is expected to increase dramatically. Aluminum nitride (AlN substrates) and silicon nitride (Si3N4 substrates) are used for most of the insulated substrates carrying these semiconductor chips. Oxygen-free copper strips are bonded to these in order to form circuits and dissipate heat. Oxygen-free copper strips are heat treated at a relatively high temperature (roughly 750 to 800°C) during this process. This causes coarsening of the grain size of the crystals on oxygen-free copper strips, which can reduce inspection accuracy in subsequent processes and worsen the appearance after plating. In addition to demand from customers for oxygen-free copper strips with high thermal resistance for this particular application, there is also demand for increased production of oxygen-free copper strips (GOFC) for a wide range of different applications.


“GOFC” is a heat-resistant oxygen-free copper strip that curbs coarsening of crystal grain size when molding insulated substrates. This makes the inspection process following semiconductor chip bonding and the SAT (scanning acoustic microscope) inspection process for sections soldered to the chip easier during subsequent processes. In addition to providing improved inspection accuracy over standard oxygen-free copper, this helps to improve power module reliability and ensure stable quality.
“GOFC” does not use added elements to maintain thermal resistance, so it complies with C1020 (JIS H 3100) used for many power semi-conductors. This makes the switchover and approval procedures easier for customers.
Crystal grain coarsening is an issue even for applications other than insulated substrates. For items that are diffusion bonded at high temperature or silver brazed, crystal grain coarsening inside copper material when bending during subsequent processes can result in a rough surface (sometimes referred to as “orange peeling”), worsening the appearance after plating. “GOFC” curbs grain coarsening, maintaining the state of the surface.

Oxygen-free copper with high thermal conductivity will play an increasingly important role as operating temperatures continue to rise in response to demands for increased power semi-conductor efficiency. Customers require contradictory characteristics (“high purity” and “thermal resistance”) from oxygen-free copper to maintain high thermal conductivity and connection reliability. “GOFC” heat-resistant oxygen-free copper strips meet both of these requirements, helping to resolve customers’ issues and increasing the value of products.

Support for the environment

This product (oxygen-free copper) includes functionality to contribute toward “preventing global warming” and is certified by Furukawa Electric as an environmentally-friendly product (e-friendly).

e-Friendly mark

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 967.3 billion (approximately USD 8.7B) for the fiscal year ended March 31, 2018.