Micro Springs from 0.1 mm Wire: Design and Sourcing for Miniature Mechanisms

Springs wound from wire finer than about 0.2 mm play by different rules: material behaves differently at scale, handling causes more failures than manufacturing, and few factories can make them at all. Formosa Spring's network produces springs down to 0.1 mm wire diameter.

Where micro springs live

• Test probes (pogo pins) and semiconductor test sockets
• Board-to-board connectors and battery contacts
• Medical devices: catheters, injector pens, dental tools
• Watches, camera shutters, micro switches, relays

What changes at micro scale

• Tolerances don't shrink proportionally. A ±0.02 mm diameter tolerance is loose on a 5 mm spring, but on a 0.3 mm-OD spring it's 7% — specify tolerances by function.
• Grinding is out. Below ~0.5 mm wire, ends stay unground; design seats accordingly.
• Handling dominates yield. Tangling, electrostatic attraction, and cleaning debris matter more than coiling accuracy. Ask how springs are packaged: tubes, trays, or vibration-fed reels.
• Material certificates matter more. At 0.1 mm, one inclusion in the wire is a broken spring. Fine wire comes from a small set of qualified mills, mostly in Japan and Taiwan.

Design suggestions

Keep the spring index between 5 and 9 (harder than it sounds at this scale), avoid closed ends tighter than one dead coil, and specify force at working length with a realistic ±15% window near the 0.1 mm floor. For conductive applications, gold flash over nickel is standard.

Very few suppliers quote micro springs seriously. Send yours through our RFQ form — micro-coiling is one of the specialties of our Taiwanese factory network.