Tokyo Ohka Kogyo Brand Guidelines: From a 1936 Alkali Lab to OFPR Photoresists

Purified potash for miners’ lamps.

Tokyo Ohka Kogyo, which shortens its name to TOK, began in April 1936 as the Tokyo Ohka Research Laboratory in Shinagawa, then part of Tokyo City. Its founder was Shigemasa Mukai. The company’s Japanese chronology says the laboratory started by making purified potassium hydroxide, and its English history says Mukai had spent years developing batteries for the lamps on coal miners’ caps; the potassium hydroxide, of higher purity than imported grades in the company’s telling, was the electrolyte for those alkaline batteries. Chlorinated naphthalene followed in 1937 and sodium hydroxide in 1938.

In October 1940 the laboratory was reorganised as a joint-stock company, Tokyo Ohka Kogyo Co., Ltd., and TOK counts that as its founding: it marked its eightieth anniversary in 2020.

The company was formed in wartime, and its chronology covers those years in a few entries. It lists the start of reagent-grade potassium and sodium hydroxide in September 1941, and its next entry is benzyl chloride in June 1948. A corporate-history summary on the Japanese site the-shashi.com, updated in October 2026 and citing a 1986 article in the Securities Analysts Journal, says that from 1940 to 1945, under the wartime planned economy, purified potassium and sodium hydroxide were treated as important electrolytes for the alkaline batteries in coal-mine lamps. The same summary says that after 1945 the mines pressed the company for supplies, and that chlorinated naphthalene was supplied as a filler for capacitors in telephones brought in by the American occupation forces.

Organic chemistry came next. The chronology lists benzyl alcohol and benzyl acetate in 1949, Ohka Seal, an adhesive for the phosphors in black-and-white television tubes, in 1955, and cinnamic acid in 1956. In October 1962 TOK began making TPR, a photoresist for printed circuit boards, and in January 1967 it opened the Sagami plant in Kanagawa, now its TOK Technology and Innovation Center.

Negative, then positive, resists for chips.

TOK moved from circuit boards to semiconductors in March 1968, when, its chronology says, it started producing OMR-81, a negative-tone photoresist for semiconductors. In December 1972 it developed OFPR-2, which the company describes as the first positive-tone photoresist for semiconductors made in Japan. It also built equipment: in 1977 it developed the OAPM, which it calls the world’s first fully automatic single-wafer plasma etching system, and its chronology also lists plasma ashers from 1971 and coaters from 1981; in March 2023 it transferred its equipment business to AIMECHATEC.

Printing was a parallel line. Under a development contract from a government agency, the company says, it produced the nylon-based photopolymer plate Topron in 1974, followed by Elaslon, a photosensitive rubber plate for flexographic printing, in 1975, and in 1984 it opened a plant in Yamanashi just for photopolymer printing plates.

Volume production of semiconductor resists began at Utsunomiya, which TOK opened in June 1981 as its first full-scale photoresist plant, followed by plants at Aso in 1984, Gotemba in 1987 and Koriyama in 1994. Its history lists photoresists for each new exposure wavelength: a deep-UV production line at Koriyama in 1997, for the KrF excimer-laser resist that the company says many chipmakers adopted as a standard, and the TARF-P series for ArF lasers in 2001.

Production abroad started in the United States. TOK set up Ohka America in California in 1987 and opened a plant in Oregon in 1993, its first overseas manufacturing site; it established TOK Taiwan in 1998, Chang Chun TOK in Changshu, China, in 2004, and TOK Advanced Materials in South Korea in 2012, a joint venture with Samsung C&T, according to Japanese Wikipedia. The company says the Tongluo plant in Taiwan opened in 2014 and a plant at Pyeongtaek in South Korea was completed in September 2026. Tom’s Hardware described TOK in May 2026 as the largest photoresist supplier, with a presence in Taiwan for more than a decade alongside its customer TSMC.

Design and documentation.

Silicon-wafer and chip-materials makers sell to a small number of very large customers, and their public image is built for engineers, investors and recruits rather than shoppers. Most of what they make never reaches a consumer’s hand: a polished wafer, a bottle of photoresist or a photomask is used up or hidden inside a chip long before anything is sold in a shop.

Their pictures tend to come from the factory floor. Corporate reports and websites in this field favour mirror-polished silicon wafers catching the light of a cleanroom, cylindrical crystal ingots drawn slowly out of a furnace, photolithography bays lit in amber to protect light-sensitive resists, and racks of high-purity chemical bottles. People appear mostly as technicians in full-body cleanroom suits, often called bunny suits, with only their eyes showing.

Names in this group often record a history. Shin-Etsu joins two old Japanese provinces, and SUMCO is an acronym of the company formed by a 1999 merger. The palettes in these guides are our own interpretations, not official colours.

The industry meets at its trade shows. SEMICON West in the United States, SEMICON Taiwan in Taipei and SEMICON Japan in Tokyo bring wafer, chemical and equipment suppliers onto the same floor as chipmakers, and booths there show the same vocabulary of wafers, ingots and cleanroom imagery. This guide sets out what can be checked about each company — who founded it, who owns it, where it makes its products — and marks clearly what rests only on the company’s own word.

A long name and a short one.

The company has kept its full Japanese name, Tokyo Ohka Kogyo, while trading under the initials TOK. Its shares were listed on the second section of the Tokyo Stock Exchange in July 1986 and moved to the first section in September 1990; Japanese Wikipedia lists it on the Prime market and in the JPX-Nikkei Index 400. In August 2000 it moved its head office to Kawasaki, onto the site where its Kawasaki plant had stood, and it remains there, in Nakahara ward.

Its business today, as the company lists it, covers materials for semiconductor manufacturing, semiconductor packaging, image sensors and MEMS, along with high-purity chemicals and new businesses. The company names two core technologies: microfabrication with photoresists and the high purification of chemicals. In February 2025 the company made micro resist technology GmbH of Germany a subsidiary, and in October 2026 it established a new company, Zero Newton Solutions.

TOK presents its long-term plan as “tok Vision 2030,” setting the short name in lower case, and says it is working towards becoming a hundred-year company in 2040. Its laboratories and research buildings are concentrated at the Sagami site in Samukawa, Kanagawa, renamed in April 2024 as the TOK Technology and Innovation Center.

The company’s English history tells its story largely through product names: OMR, OFPR, TARF-P and TMMR, a permanent photoresist for MEMS developed in 2003. Other entries record a dielectric sheet for plasma displays and a positive photoresist for organic EL displays, both in 2001, and wafer-handling systems for through-silicon vias in 2008. In 2011 it organised a marketing division and a new-business development division, and in 2018 an AI promotion division, the history adds.

For a design guide, Tokyo Ohka Kogyo shows how a company can trace a straight line from its first product to its present one, and say so in its own chronology. Compare JSR, another Japanese photoresist maker, and Shin-Etsu Chemical. For this guide we use a deep green and an amber with a sans, an unofficial interpretation; no product or logo is reproduced.

Keep Tokyo Ohka Kogyo’s identity on hand — save it to a board in the Made Good inspiration library.