Button springs (also commonly known as “pot springs,” “metal domes,” or “snap domes”) are made from ultra-thin (0.05 mm–0.1 mm thick) or ultra-thick (typically with higher hardness) 301 or 304 stainless steel. Button springs are a critical component of switches.
They are primarily used in membrane switches, dome-contact switches, PCBs, FPCs, medical devices, and other products. How button springs work: The button spring on a membrane switch is positioned over a conductive area on the PCB (mostly above the gold fingers on the circuit board). When pressed, the center of the spring depresses and makes contact with the circuit on the PCB, thereby forming a circuit. Current flows, allowing the entire product to function normally.
Hongmao’s metal springs are classified by shape into: round metal springs, cross-shaped metal springs, triangular metal springs, and oval metal springs. Diameters range from 3 mm to 20 mm, and actuation forces range from 100 g to 600 gf. Based on surface plating treatments, they can also be categorized as: gold-plated, nickel-plated, silver-plated, and mirror-finished. Both single-sided and double-sided plating options are available.
Coconut-style round metal bumps (oval metal bumps, rectangular metal bumps) are oval-shaped switch contacts specifically designed for installation on double-sided printed circuit boards, flexible circuits, and thin films.
The actuation force of round metal bumpers typically ranges from 100 to 500 gf, and parameters such as rebound force, click sound, travel, and height can be adjusted according to customer requirements. Regardless of the size or actuation force you need, we will do our utmost to manufacture them for you.
Dimensions and Specifications
Common Sizes: Common length-by-width combinations range from 3.0 mm to 5.0 mm, with typical sizes including 4 × 2.8 mm, 4 × 3.05 mm, 4.5 × 3.3 mm, and 5 × 3.7 mm.
Size Range: Smaller models can be as small as the 2mm range (e.g., Φ2 half-round), while larger models can reach 17.78×8.89mm, 25.4×12.7mm, or even larger, with a maximum diameter of up to 37mm.
Operating Force
Typical Forces: 130gf, 160gf, and 180gf are the most common and widely used force options on the market.
Force Range: The common range of options is approximately 100 gf to 180 gf. A broader custom range is available, starting at 90 gf and extending up to 400 gf or higher.
Stroke (Pressure Depth)
Typical Travel: Typically between 0.14 mm and 0.25 mm, depending on the size and actuation force design. The overall travel is “short,” providing a balanced feel. For example, the travel for a 3×2.5 mm size is approximately 0.14–0.16 mm, while that for a 4×3.05 mm size is around 0.18–0.22 mm.
Contact Configuration
Similar to round pot-type switches, oval-shaped switches also offer various contact configurations, including no contacts, single contact (1 contact), 4 contacts, and 5 contacts. Models with 5 contacts are relatively common and enhance switching reliability in complex environments.
