0000720500 2026-06-01 2026-06-01 0000720500 1 2026-06-01 2026-06-01 0000720500 2 2026-06-01 2026-06-01 0000720500 3 2026-06-01 2026-06-01 0000720500 4 2026-06-01 2026-06-01 0000720500 5 2026-06-01 2026-06-01 0000720500 6 2026-06-01 2026-06-01 iso4217:USD pure S-3 S-3MEF EX-FILING FEES 333-294296 0000720500 AMTECH SYSTEMS INC N/A N/A 0.0001381 0.0001381 0.0001381 0.0001381 0.0001381 S-3 AMTECH SYSTEMS INC Equity Common Stock, par value $0.01 per share ("Common Stock") true Equity Preferred Stock, par value $0.01 per share ("Preferred Stock") true Debt Debt Securities true Other Warrants true Other Units true false Unallocated (Universal) Shelf true 10000000.00 0.0001381 1381.00 10000000.00 1381.00 0.00 0.00 1381.00 (1) Calculated pursuant to 457(o) under the Securities Act of 1933, as amended, based on the proposed maximum aggregate offering price. (2) The registrant previously registered securities at an aggregate offering price not to exceed $50,000,000 on a Registration Statement on Form S-3 (File No. 333-294296), which was filed by the registrant on March 13, 2026 and declared effective on March 23, 2026 (the "Prior Registration Statement"). In accordance with Rule 462(b) under the Securities Act of 1933, as amended, and General Instruction IV.A of Form S-3, an additional number of securities having a proposed maximum aggregate offering price of $10,000,000 is hereby registered on this Registration Statement on Form S-3 (the "Registration Statement"), representing no more than 20% of the maximum aggregate offering price of unsold securities under the Prior Registration Statement. In no event will the maximum aggregate offering price of all securities issued pursuant to this Registration Statement and the Prior Registration Statement exceed that registered under such registration statements.