Hitachi Cable, Ltd. will step up backing plate manufacturing capacity at its Tsuchiura Works in a bid to address growing demand for the backing plates used in sputtering systems, manufacturing systems for LCD panels, semiconductor devices, and recording media such as DVDs. The expanded capacity is slated to go online in February 2007.

Backing plates serve as target material cooling plates and as sputtering electrodes in sputtering systems used to manufacture LCD panels, semiconductor devices, and recordable media such as DVDs. Backing plate materials must offer not just high electrical and thermal conductivity, but low gas release. With excellent performance in these various aspects, copper is a popular material.

Making a water-cooled backing plate with high cooling capability involves cutting grooves on the plate body, joining the cover to the body, and machining the surface to form cooling water channels inside the plate. Electronic beam welding has conventionally been used to weld the plate body and the cover. But this technique entails various problems, including warping due to thermal impact and vulnerability of the area surrounding the weld to softening.

For this reason, Hitachi Cable, Ltd. has used "friction stir welding"- a welding method that ensures minimal warping due to heat thanks to its low temperature rise during welding. This gives high welding strength for the welding of the backing plate body and the cover to enable large, high-quality backing plates. Hitachi Cable has used this process since 2001, when it introduced the world's first friction application of stir welding for volume production of copper backing plates.

Recent years have seen a growing market for slim TVs incorporating LCD panels, widespread popularity of DVD media and the emergence of new DVD standards, and increasing demand for systems to manufacture these products - all trends that have generated growing demand for backing plates. To meet this demand, we plan to invest a total of 500 million yen in backing plate manufacturing facilities at our Tsuchiura Works. Primarily targeting expanded manufacturing capacity, this investment will involve the addition of machining and friction stir welding equipment. We project backing plate sales to expand from approximately 2 billion yen in fiscal 2006 to approximately 3 billion yen in fiscal 2007.

Hitachi Cable plans to improve its supply capacity to address growing demand for backing plates, taking advantage of its position as a total manufacturer of copper to push ahead with backing plates that offer better heat radiating capabilities and materials with excellent heat resistance and strength. The overall goal is to enhance our services.

Appearance of Backing Plate

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  Left:Square backing plate / Right:Round backing plate

How to use a backing plate

Discovered by TWI (The Welding Institute, a British public welding institute, current TWI Ltd.) in 1991, the basic principle underlying friction stir welding involves inserting a rotating tool into the area to be welded and moving the tool along the area to form the weld. The welding method harnesses the frictional heat generated between the material to be welded and the rotating tool, enabling the rotating tool to mix the material softened by frictional heat for welding. As described above, the process of friction stir welding differs dramatically from electronic beam welding and other conventional welding methods in that the material is not melted. Friction stir welding offers revolutionary capacity to minimize post-welding deformation and warping.

Commercial applications of friction stir welding have been limited to aluminum alloys used in body structures of rolling stock and ships; application to copper alloys have remained at the research stage. But in 2001, following joint study of various tools and welding conditions with Hitachi, Ltd , we successfully commercialized copper friction stir welding and initiated volume production of copper backing plate by this method for the first time anywhere in the world.

Outline of the Tsuchiura Works