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.
Square-shaped metal dome with a dot is also known as a cross-shaped metal dome or a four-corner metal dome. It gets its name from its quadrilateral body and four support legs, while “with a center dot” refers to the tiny raised dot at its center.
The Key Difference Between “With a Center Dot” and “Without a Center Dot”
The “with a center dot” design is an important variant of this type of spring clip, offering several practical advantages:
Enhanced dust resistance: This is the most significant advantage. A dot-type spring contact makes contact with the circuit board via a raised dot rather than its entire flat surface. If dust enters the environment, it is likely to settle around the dot, causing minimal interference with the central contact point. Even if a small amount of dust accumulates on the dot, pressing the switch a few times is usually enough to dislodge it and restore conductivity. In contrast, a flat-contact spring contact relies on a flat surface for contact; once dust covers the contact surface, it may lead to poor contact.
More Stable Contact: The raised-dot structure applies pressure to the circuit board contact point in a more concentrated and reliable manner, ensuring stable contact.
Clearer Tactile Feedback: Compared to flat contact, dot contact provides a more focused and distinct tactile sensation when pressed.
Suitable for More Demanding Applications: The total height of dot-style leaf springs is typically slightly greater than that of their flat counterparts, making them suitable for designs with specific requirements regarding key travel or internal clearance.
Hongmao's metal springs are categorized by shape into: circular 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 classified as: gold-plated, nickel-plated, silver-plated, and mirror-finished. Both single-sided and double-sided plating options are available.
Product Applications: Widely used in mobile phones, cameras, computers, remote controls, printers, gaming devices, smart wearable devices, financial terminals, medical equipment, machinery, sports equipment, home appliances, automotive electronics, and other product sectors.
In addition to our extensive standard metal spring sheet product line, we also offer custom metal spring sheet design services to meet your specific application needs.
Whether you require custom dimensions, shapes, actuation force, return force, or travel; with tabs or holes—we will provide precision metal springs tailored to your application needs based on your design, drawings, or samples.
