Company history

Taiyo began in September 1953 as Taiyo Ink Mfg. Co., Ltd., a mid-size maker of printing inks — silk-screen and oil-based inks — set up in Minato, Tokyo, by the founding Kawahara family and riding the postwar expansion of Japan’s print market. Its craft, though, was chemistry: the resin, pigment and dispersion know-how it built for ink was general-purpose, not bound to printing, and that latent versatility is what would let a printer change trades.

The turn came in 1970, when Taiyo began selling materials for printed wiring boards and pointed its ink chemistry at electronics. In 1973 it developed an epoxy, heat-curing solder-resist ink — the protective film that covers the parts of a board that must take no solder — the first core of its transformation from printer into an electronic-materials maker. In 1984 came a photo-developable solder resist that formed fine patterns by ultraviolet exposure, the material that would carry the high-density chip packaging of the 1990s.

In November 1993 the basic patent for that developable solder resist was granted in Japan, fixing the technical basis for a world-leading share. Following its customers’ shift of production into Asia, Taiyo built plants abroad — Korea in 1988 (its first), the United States in 1990, Taiwan in 1996, Singapore and Hong Kong in 1999 — and in 1990 it went public through over-the-counter registration.

On 18 January 2001 Taiyo listed on the First Section of the Tokyo Stock Exchange — the first new listing of the year, and, as it liked to note, the 21st century’s first First-Section debut. That December it set up a production subsidiary in Suzhou, China, and as printed-circuit-board output moved wholesale onto the mainland through the 2000s, the Suzhou plant became the hinge of a global supply network.

Spanning Japan, Korea, Taiwan, China and Southeast Asia, Taiyo built and held the top share of the world market for printed-circuit-board solder resist. Through these years the company was led by Yuichi Kamayachi, president from 2004 and later group chief executive — an engineer who had risen through development and steered the overseas build-out, the last of the technically trained chiefs before the top of the house changed character.

In October 2010 Taiyo reorganized into a holding company, changing its name from Taiyo Ink Mfg. Co., Ltd. to Taiyo Holdings Co., Ltd. and pushing the domestic solder-resist business down into an operating subsidiary that took over the old Taiyo Ink name. The listed parent would run strategy, finance and M&A; the operating company would run the ink. In 2011 the presidency passed to Eiji Sato — a certified public accountant, neither an engineer nor a Kawahara — who left the technical floor to the research executives and kept finance discipline, acquisitions, capital returns and group governance in his own hands.

What followed was diversification by acquisition. Taiyo brought in a Taiwanese maker in 2013 (later the world leader in solder resist for flexible boards), founded Taiyo Green Energy in 2014 to enter renewable power, and in 2015 acquired the dye-and-chemical maker Chugai Kasei (now Taiyo Fine Chemical). In 2017 it struck a capital and business alliance with the printing-ink giant DIC.

The decisive step outward came the same year: in 2017 Taiyo founded Taiyo Pharma and entered prescription pharmaceuticals, its first real break from an electronics-only portfolio, adding contract-manufacturing capacity through Taiyo Pharma Tech in 2019. The logic was to steady a business held hostage to the electronics cycle with one that ran on a different clock; revenue climbed as the new pillars took hold.

Pandemic-era demand for electronics carried Taiyo to record profits and its highest revenue yet. The group kept widening — a Vietnam plant in 2020, and altogether new fields in systems development and dental products by 2024 — moved to the Tokyo exchange’s Prime Market in 2022, and adopted an audit-committee board in 2024. On the surface, the accountant’s diversification looked vindicated.

Beneath it, discontent had gathered. The very diversification Sato had led — the pharmaceutical bet above all — drew fire on capital efficiency: goodwill had piled up faster than the earnings to justify it. In 2025 the Hong Kong activist Oasis Management, the top shareholder DIC and the founding Kawahara family converged, and at the June annual meeting Eiji Sato’s reappointment as a director was voted down — a listed company’s chief unseated by his own shareholders, a rare thing in Japan.

From there the question turned to who would own the company at all. Several funds, among them NSSK and KKR, offered to take Taiyo private; in 2026 the board accepted a take-private led by KKR. The world’s leading solder-resist maker had entered the largest structural change of its seventy-odd years — and under whose discipline its dominant niche will next be run is, for now, unsettled.