Isc

ISC makes test sockets that connect packaged semiconductor chips to test equipment; the socket is a consumable part that wears out during testing.

Sockets are split by contact method into silicone rubber and pogo (spring pin) types, and the company was first in the world to commercialize silicone rubber test sockets in 2003 and holds more than half of that market.

According to a January 2026 Mirae Asset Securities note, the memory test socket market is effectively all rubber-type with ISC at roughly 80% share, while non-memory is a mix of pogo and rubber with a shift toward rubber underway.

Beyond rubber sockets, the line-up includes pogo sockets, burn-in sockets for high-temperature testing, and interface boards. The same note said production is about 90% in Vietnam and 10% in Korea.

Customers include Samsung Electronics, SK hynix and other domestic and overseas chipmakers, plus North American GPU and ASIC designers, with high-spec datacenter products now a larger share.

SKC acquired the company in October 2023, bringing it into the SK group, where it handles back-end and equipment/materials businesses with test sockets as the core product.

An equipment and materials business acquired in the first half of 2025 added high-speed burn-in testers, board-level testers and DRAM cleaning chemicals for HBM to the portfolio (the targets were iSemi, a back-end equipment firm from SK enpulse, and PCB supplier Techdream, for a reported KRW 41.3bn).

Competitively, ISC leans on its rubber socket edge, and Korea Investment & Securities described the SLT market as forming a two-player structure between ISC and Taiwan's Winway.

Earnings have swung sharply with the cycle.

From 2022 revenue of KRW 178.9bn and operating profit of KRW 55.9bn (31.2% margin), profit collapsed in 2023 to KRW 10.7bn on revenue of KRW 140.2bn (7.7%), then recovered to KRW 174.5bn revenue and KRW 44.8bn operating profit (25.7%) in 2024 and KRW 220.2bn and KRW 60.1bn (27.3%) in 2025.

Net profit attributable to owners was KRW 56.1bn in 2025 versus KRW 54.7bn in 2024; in 2024 total net profit of KRW 54.9bn exceeded operating profit, meaning non-operating items lifted the bottom line, whereas in 2025 net profit came in below operating profit.

FnGuide summarized the 2025 results as revenue up 26.2%, operating profit up 34.1% and net profit up 2.7%, driven by AI chip test socket demand and system-level test socket orders from AI accelerator and ASIC customers.

Quarterly, revenue and operating profit rose from KRW 51.7bn and KRW 13.7bn in Q2 2025 to KRW 64.5bn and KRW 17.4bn in Q3, and KRW 72.3bn and KRW 21.9bn in Q4.

Q1 2026 delivered KRW 68.3bn revenue and KRW 23.6bn operating profit for a 34.6% margin, and the company said it achieved a record quarterly operating profit despite Q1 being a seasonal low, helped by AI GPU, ASIC and high-end memory demand.

In Q2 2026 revenue set another high at KRW 72.9bn, but operating profit was KRW 21.3bn for a 29.2% margin, below the prior quarter, and net profit to owners eased from KRW 20.5bn to KRW 19.3bn.

Summed over the last four quarters (Q3 2025 to Q2 2026), revenue reached KRW 278.1bn and operating profit KRW 84.3bn, a roughly 30.3% margin, already above full-year 2025 revenue.

The balance sheet is light, with equity of KRW 537.3bn against liabilities of KRW 85.2bn and a 15.9% debt-to-equity ratio at end-2025, yet operating cash flow declined from KRW 50.7bn in 2024 to KRW 41.7bn in 2025, showing that profit growth did not fully convert into cash.

Test socket demand tracks both chip shipment volumes and the pace of new product development.

Mirae Asset Securities noted that sockets see high-priced R&D demand early in a chip's development and replacement demand as tool utilization rises after mass production begins, implying demand across the full HBM generation transition cycle. The current cycle is centered on AI datacenters.

Korea Investment & Securities forecast that as the dominant AI accelerator form factor expands from baseboard to rack and from rack to pod, adoption of system-level test, which checks combined performance across multiple chips rather than a single die, will widen substantially.

On the other side, consumer IT socket sales for smartphones, PCs and wearables were described as somewhat weak, offset by datacenter growth. With end demand concentrated in AI, a consumer IT recovery remains only a secondary earnings variable for now.

Competitively, the technical barrier in rubber sockets is the main defense, but the view that the early SLT socket market will be an oligopoly between ISC and Winway also means share competition among few players feeds directly into pricing and margins.

Mirae Asset Securities said the AI share of revenue expanded from 40% in 2024 to 67% in Q3 2025, improving the mix toward higher-value products. In cycle terms, the position looks closer to an expansion phase with high utilization across memory and non-memory, which also raises the exposure to any subsequent downturn.

The core of the company's disclosed plan is capacity expansion.

In its April 2026 Q1 release, ISC said it had pulled forward completion of the Vietnam Plant 1 expansion for full operation from October, aims to finish new Plant 2 within the year to maximize capacity, and will consolidate domestic production while applying manufacturing AI to lift productivity and operating efficiency.

According to May 2026 reporting, the company guided this year's capex to KRW 80-100bn, far above its five-year average of KRW 15bn, for the Plant 1 expansion and Plant 2 build, expanding total capacity from about KRW 290bn to KRW 400bn of output value.

Domestically, it decided to invest KRW 35bn to expand the Songdo site in Incheon and consolidate scattered plants and R&D functions there. On products, the company said Q1 2026 AI chip test socket sales for GPUs and ASICs grew 191% year on year and that system-level test accounted for more than 60% of the mix.

Application scope is also widening: in July 2026 the company said it had moved datacenter test sockets into full mass production and was running quality evaluations with customers on next-generation chip products, extending socket coverage to HBM, HBF, CPO and SOCAMM2.

Among brokerage estimates, iM Securities in a March 2026 note projected FY2026 revenue of KRW 329bn and operating profit of KRW 100.3bn. On target prices, Korea Investment & Securities said on April 28, 2026 that it was maintaining a buy rating and a target price of KRW 300,000.

These plans, however, rest on the expansion staying on schedule, yields stabilizing at new lines, and customer ramp timetables lining up.