Q1 2026 Quarterly Report — PCB Maker Absorbs Subsidiary Teranix, Credit Rating Upgraded to BBB-

Quarterly Report 6.5 Korea Circuit Co., Ltd. 1 Y 130111-0026749 QUARTERLY REPORT (55th Term) Fiscal Year: January 1, 2026 – March 31, 2026 To: Financial Services Commission, Korea Exchange Date: May 15, 2026 Filing Entity Type: Listed Company Exemption Reason: None Company Name: Korea Circuit Co., Ltd. CEO: Jang Se-jun Headquarters: 9, Gangchon-ro 139beon-gil, Danwon-gu, Ansan-si, Gyeonggi-do Tel: 031-491-3061 Website: https://www.kcg.co.kr Preparer: Lee Han-gyun, Head of Management Division TABLE OF CONTENTS 【CEO Certification】 — p.1 I. Company Overview — p.3 1. Company Overview — p.3 2. Corporate History — p.6 3. Changes in Capital Stock — p.8 4. Total Shares — p.8 5. Articles of Incorporation — p.13 II. Business Operations — p.19 1. Business Overview — p.19 2. Key Products and Services — p.20 3. Raw Materials and Production Facilities — p.21 4. Sales and Orders — p.25 5. Risk Management and Derivatives — p.28 6. Major Contracts and R&D — p.34 7. Other Reference Matters — p.37 III. Financial Matters — p.46 1. Summary Financial Information — p.46 2. Consolidated Financial Statements — p.48 3. Notes to Consolidated FS — p.55 4. Separate Financial Statements — p.114 5. Notes to Separate FS — p.119 6. Dividends — p.183 7. Securities Issuance Financing — p.187 8. Other Financial Matters — p.188 IV. Management Discussion and Analysis — p.195 V. External Auditor's Opinion — p.196 VI. Board and Corporate Governance — p.200 VII. Shareholders — p.211 VIII. Officers and Employees — p.216 IX. Affiliated Companies — p.222 X. Transactions with Major Shareholders — p.223 XI. Other Matters for Investor Protection — p.224 XII. Detailed Tables — p.235 【Expert Confirmation】 — p.240 I. COMPANY OVERVIEW 1. Company Overview A. Consolidated Subsidiaries Summary (in companies): Listed: 2 (start) → 2 (end), no changes Unlisted: 4 (start) → 4 (end), no changes Total: 6 consolidated subsidiaries, 4 major subsidiaries See 'Detailed Table 1 — Consolidated Subsidiaries' for details B. Changes in Consolidation Scope: None (no new consolidations, no removals) C. Legal and Commercial Name: Korean: 주식회사 코리아써키트 English: KOREA CIRCUIT CO., LTD. D. Founding Date and Duration: Founded April 11, 1972, with PCB (Printed Circuit Board) manufacturing and sales as primary business. E. Headquarters Address, Phone, Website: Address: 9, Gangchon-ro 139beon-gil, Danwon-gu, Ansan-si, Gyeonggi-do (Seonggok-dong) Tel: 031-491-3061 Website: https://www.kcg.co.kr F. SME / Venture / Mid-sized Enterprise Classification: None of the above. G. Main Business and Future Plans: The parent company is a specialized PCB manufacturer producing PCBs for mobile communication devices, memory modules, LCDs, and semiconductor packaging substrates, sold to domestic and overseas electronics manufacturers. Subsidiary Teranix Co., Ltd., a specialty PCB (LED PCB, etc.) manufacturer, was merged into Korea Circuit effective February 25, 2026, with its PCB manufacturing operations absorbed by the parent. Going forward, the surviving Teranix entity will use its retained resources to pursue businesses related to the Young Poong Group's electronics affiliates, including real estate management, factory design and renovation, new factory acquisition and disposal, and overseas factory construction. Subsidiary Interflex Co., Ltd. specializes in flexible printed circuit boards (FPCBs). Subsidiary Signetics Co., Ltd. operates in semiconductor packaging manufacturing. Overseas, KOREA CIRCUIT VINA COMPANY LIMITED and INTERFLEX VINA CO., LTD. operate PCB manufacturing in Vietnam, and SIGNETICS HIGH TECHNOLOGY USA INC handles overseas semiconductor packaging sales. See Section II for details. H. Credit Rating Information: 2026-04-16: DNA PLUS Report, BBB-, E-Credible 2025-04-21: DNA PLUS Report, BB+, E-Credible 2024-05-09: DNA PLUS Report, BBB+, E-Credible Note: The company has not issued corporate bonds during the disclosure period... [Translation truncated]