Who Fositek is
Fositek (6805.TW), traded as 富世達, makes precision mechanical parts: foldable-phone hinges, notebook hinges, and — the line that changed the mix — server slides and liquid-cooling quick disconnects. It works with a chassis-maker parent on slide design, which management cites as the reason it can join new rack programmes early and stay off competitors' patents.
It is not on NVIDIA's published 800 VDC list. The cooling slot is the QD: the dripless fitting that lets a serviceable AI tray come apart. Management claims a main-supplier seat on NVIDIA GB200 / GB300 Switch QDs. Blackwell / Rubin cold-plate QDs are NVIDIA-decided.
Business mix
By full-year 2025 the mix had flipped hard toward servers:
- Foldable-phone hinges — 56.4% of sales, down from 82.6% in 2024, even though the absolute dollar still grew. Huawei is the named account; Fositek says its share there has stayed fixed.
- Server products (slides + QDs) — 36.3%, from 5.3%. Revenue NT$4.505bn, +936%.
- Notebook hinges — 6.4%, from 10.9%.
FY2025 revenue NT$12.414bn, gross margin 26.34%, net income NT$2.125bn, EPS NT$31. Q4 gross margin 29.05%, EPS NT$10.96. Stated product-margin order: server > phone hinge > PC hinge.
Where it sits in the NVIDIA 800 VDC stack
The liquid-cooling block on NVIDIA's diagram: cold plate, manifold, QD, CDU, 45°C loop.
Fositek does not sell the plate or the CDU. It sells the fitting:
- UQD — chassis-to-rack, including floating joints.
- MQD — smaller, inside a tight chassis.
- Micro QD — sampling with customers; patents filed.
- Two-phase QD — higher internal pressure when the fluid boils; harder to mate and unmate; being designed with the group.
2026 capacity targets: slides 350,000 sets a month, QDs 3 million pcs a month. Vietnam is getting automated lines. AWS and Google TPU QDs were still in qualification on the March 2026 call. ASIC QDs are a second-tier part: price and allocation are set by the end customer, not only by the chassis parent.
The March 2026 call never said 800 V. The 800V read is the same as Auras and AVC: GB300, Blackwell, Rubin and CSP ASIC cabinets go liquid, so QD count per tray rises. Welding the loop shut is, on this call, "not practical" in a heavy AI chassis.
Coverage note
One note, from 5 March 2026, covering Q4 and full-year 2025. The May and August 2026 calls in this archive failed transcription, so this is the latest usable file.