OCC stands for Ohno Continuous Casting. This technique was developed and patented by Dr. Atsumi Ohno in the 80s. The product of this process shares an unique property of single-crystal. As of today, these patents are expired. However, this doesn't mean that every wire manufacturer can make OCC wires. The OCC process requires professional equipment and accurate controls for pressures, temperature in various stages. Any process variation will spoil the desired single-crystal structure.

Left: OCC process, Right: traditional casting process

Dr. Atsumi traveled and stayed in Taiwan for a couple years in the 90s and he licensed his OCC technologies to ITRI (Industrial Technology Research Institute). ITRI developed prototypes for a complete OCC process successfully. This technology was then transferred to a couple Taiwanese companies where some of them remain manufacturing high quality OCC cables.

In the past years, OCC was covered by a mysterious veil. Some claim the OCC can increase the purity of silver from 5N (5 digits of 9, ie. 99.999%) to 7N. This is not true. As you can find in the references at the bottom of this article. The OCC process is a "casting" process, not a "refining process". Indeed, in the OCC process some impurity of the raw material will float at the surface of the melt metal and will result in a better purity than the raw materiel but it can not be an order of magnitude. In a nut-shell, the purity of the OCC product will not change much compared to the raw material. In the industry 4N silver is considered pure. It is rare to find a good 5N source let alone 6N or 7N. For copper the story is a little different. Due to a need in the semiconductor industry for bonding wires 6N copper is quite common in the market.

As audio DIY enthusiasts we understand the needs for quality OCC cables for the home-brewers. We understand the customers want to know everything about the wire they buy. Our technology is based on the same technology ITRI licensed from Dr. Atsumi. The process is refined over the past decade to reduce the production cost and enhance the quality. We provide proof of purity for the raw material. In each OCC batch we also provide microscopic photos of the crystal structure issued and validated by ITRI. Currently we offer bare solid core 5N silver wire from 10AWG to 34 AWG or 0.4mm to 2.6mm.

Please contact us for detail.

For readers that are interested in the OCC process, below are links to the patents Dr. Atsumi filed in US:

Continuous metal casting

Publication number US4515204 A
Application number US 06/449,650
Publication date May 7, 1985
Filing date Dec 14, 1982
Priority date Dec 15, 1982


Publication number US4605056 A
Application number US 06/620,019
Publication date Aug 12, 1986
Filing date Jun 13, 1984
Priority date Jun 13, 1983


Method of producing a metallic member having a unidirectionally solidified structure

Publication number US4665970 A
Application number US 06/800,040
Publication date May 19, 1987
Filing date Nov 20, 1985
Priority date Nov 20, 1985


Process for continuous casting of metal ribbon

Publication number US4789022 A
Application number US 07/171,189
Publication date Dec 6, 1988
Filing date Mar 18, 1988
Priority date Nov 15, 1985


Method for horizontal continuous casting of metal strip and apparatus

Publication number US5074353 A
Application number US 07/617,205
Publication date Dec 24, 1991
Filing date Nov 23, 1990
Priority date Feb 19, 1990