We trace our start to the Tokyo Ohka Kenkyujo (Applied Chemistry Laboratory), which was founded in 1936. The joint-stock company TOKYO OHKA KOGYO CO., LTD. (TOK) was established in 1940, and celebrated its 75th anniversary in 2015.

Our stock was listed on the Second Section of the Tokyo Stock Exchange in July 1986, and was transferred to First Section in September 1990.
In addition, in April 2022, the market was transferred from the First Section to the Prime Market due to a reorganization of the Tokyo Stock Exchange's market segmentation.

TOK's local code is 4186.

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It is 100.

Each year, we announce the first quarter business results at the beginning of August, the interim business results at the beginning of November, the third quarter business results at the beginning of February, and the term-end business results at the beginning of May. For more information, click here.
Financial statement data and other such information are posted on this website.

Click here for highlights, trends, and Tanshin, and click here for the webcast of presentations.

We supply an assortment of manufacturing materials centered around photoresist used in fabricating semiconductors, flat panel displays, and printed wiring boards, as well as the photoresist-related chemicals. In addition, we offer high-purity chemicals for use by industries in the fields of chemistry, electronics, pharmaceuticals, food products, and textiles. Click here for information on our business and products.

Photoresist is a kind of resin with a chemical action and change in response to light, and is also known as photosensitive resin. It is in extensive use as a material essential for microprocessing in fields such as semiconductors, flat panel displays, and printed circuit boards.

Undergoing the process of development after exposure, the exposed portion of negative tone photoresist is retained as an image, and the unexposed portion of positive tone photoresist is retained as an image.
Photo.1 was taken after exposure and development, and shows photoresist retaining an image of the portion shown by the red arrow.

The main types are a liquid type and a dry type. The dry type takes the form of a thin film and is called "dry film resist".
Mainly the liquid type is used in the field of semiconductors and liquid crystal displays (LCDs), and mainly the dry type, in that of plasma displays (PDPs) and printed circuit boards.

Photoresist is used for processing with chemicals, for example. In this processing, the image portion remains unaffected by the chemicals, such that only the other portions are etched or otherwise processed.
In Photo.2, the red portion will be processed while the blue portion will be protected by the photoresist and left unprocessed. Application of photoresist therefore enables selective processing.