Company history

Mitsui Takaaki did not want the job that made him. Assigned to the die-making section after joining Yaskawa Electric, he found the work punishing and fanatically exact, and disliked it. What changed his mind was the war. Called up and sent to the front, he looked closely at captured enemy weapons and realised they had all been press-formed from dies: where Japanese arms were machined one at a time, minutes to an hour apiece, a press could turn out sixty identical pieces a minute. The gap was the whole argument for dies, and he came home convinced.

In January 1949 he left Yaskawa — the pay was poor — and set up on his own in Yahata, Fukuoka, in the shadow of the Yahata steelworks where the steel was. The proposition was narrower than it looked. A die itself is cheap; what it is worth depends entirely on the accuracy and the endurance of the parts it punches. Motor cores for air conditioners and refrigerators had to be blanked from silicon steel sheet, identically, in enormous numbers, and the slightest wear in the die pushed the defect rate up. That was the crack in the market where precision could be sold, and Mitsui aimed at nothing else.

The proof came in stages: a fully ground, post-heat-treatment die delivered in 1954; incorporation as Mitsui Seisakusho in April 1957 on capital of $4,167 (¥2m); and in December 1958 a tungsten carbide die good for a hundred million strokes, which put the company into cemented-carbide tooling. From May 1959 it sold carbide progressive dies for motor cores — the ancestor of everything the company sells today. Sales of ¥500,000 in the founding year compounded at 40–50% a year to ¥50m by 1958 and ¥100m at the tenth anniversary in 1959; a new plant at Komine, still the head office today, opened in 1960.

In May 1966 Mitsui fixed on the IC lead frame. Integrated circuits had only just been commercialised, and the industry made lead frames by etching them chemically — a process expensive enough at volume to be a bottleneck for the chipmakers themselves. Mitsui bet that they could be stamped instead, and development eventually cut the cost of volume production to a tenth. Manufacture and sale began in June 1969, giving the company a third pillar alongside dies and motor cores.

What it did not have was a customer. Mitsui High-tec was then a small firm with under ¥2bn of annual sales, Japan’s semiconductor makers had not yet moved to volume IC production, and none of them wanted the risk of designing in a component from a company that size. So Mitsui went where the volume already was: a subsidiary in Illinois in April 1972, and from it a bulk order worth about $3.2M (¥1bn) from Texas Instruments. That order was the reference the domestic industry needed, and Mitsubishi Electric, Toshiba and others followed. Singapore came in December 1972 — a response to the yen’s revaluation after the previous year’s Nixon shock, and a cheaper base for supplying North America. In 1974 the company automated the weighing, twisting, stacking and clinching of motor cores in a system it patented worldwide and licensed for around ¥100m a year.

Concentration cuts both ways. When the 1973 oil shock froze customers’ capital spending, demand for lead frames and motor cores contracted at the same time, and in 1975 the company posted the first loss in its history. Recovery through the early 1980s was emphatic: renamed Mitsui High-tec in May 1984, it listed in Fukuoka that September on sales of ¥29bn, up 70.8%, with a 16.8% operating margin, the leading share in lead frames, and Mitsubishi Electric, Toshiba, Hitachi, TI, Motorola and Fairchild on its customer list. A quarter of sales went to Kyushu, then filling up with fabs as Japan’s “Silicon Island.” The Tokyo Stock Exchange second section followed in September 1985, and the first section in July 1991 — forty-two years from sole proprietorship.

Semiconductor packaging moved to Asia through the 1990s, and Mitsui High-tec followed it site by site: Malaysia in 1987, Tianjin in 1994, Shanghai in 1996, Taiwan in 1998, Thailand in 1999, Guangdong in 2002. By the early 2000s the company had production close to demand in all three poles — the United States, Southeast Asia and China — and the die, motor-core and lead-frame businesses built in Kitakyushu were no longer dependent on a single country.

The reach did not protect it. The autumn 2008 crisis hit collapsing chip demand, excess capacity across China and Southeast Asia, and a rising yen on the same books at once: from ¥62.9bn of sales and ¥1.7bn of net profit in FY2007, the company fell to net losses of ¥4.2bn, ¥5.0bn, ¥2.8bn and ¥1.6bn in the four years that followed. In April 2009, in the middle of it, Mitsui Yasunari — third generation of the founding family, career employee — succeeded Sakaue Takanori as president. Profitability returned in FY2012, but sales then stalled at ¥60–65bn for years: Chinese competition was pressing lead-frame prices down, and motor cores for household and industrial machines were a mature market with little growth left in them.

The way out was not a new technology but a new destination for the old one. Canada in January 2015 and Poland in September 2018 put the company near North American and European EV demand; in November 2018 it opened a plant at Kani, Gifu, dedicated to volume production of automotive motor cores. The commitment was deliberately out of proportion: $93.3M (¥10bn) of capital expenditure in FY2017 against electrical-component sales of ¥7.9bn — more than the business it was investing in earned in a year. Lead frames were under price pressure from Chinese entrants and consumer motors had stopped growing, and management chose to put the money where the demand curve was.

Drive-motor cores are the laminated steel hearts of the motors in hybrids and EVs, bought in volume by Toyota, Tesla, Honda, Nissan, Hyundai and Volkswagen. By 2022 Mitsui High-tec held 60–70% of the world market, defended by an ability to stamp ever thinner laminations that has kept both rivals and customers’ in-house programmes at bay. Sixty-five years of accumulated die accuracy, pointed at a new outlet, turned out to be a barrier to entry.

The result was a boom, then a jolt. Sales grew from ¥97.4bn in FY2020 to ¥214.9bn in FY2024 while operating profit went from ¥3.8bn to a peak of ¥22.6bn — roughly 2.2 times the revenue in four years — with the move to the TSE Prime market in April 2022, a US subsidiary in 2023 and a German one in 2024 added along the way. In FY2025 growth stopped: sales of ¥218.3bn were up only about 1.6%, operating profit fell some 21% to ¥12.7bn, and net profit dropped about 74% to ¥3.1bn as slowing EV demand, a ¥7.4bn impairment of surplus production equipment and the fading tailwind of the weak yen landed together. Under Mitsui Yasunari’s long tenure the company is expanding again — Ozu in Kumamoto, Kama in Fukuoka, the Americas and China under a plan called Vision 2030 — while strengthening a board it has been opening to outsiders since the 1990s. Whether a business built on one technique can hold its footing through the EV demand cycle is the question of its next decade.