If your custom silicone keypad needs a tactile response, then metal domes are typically the best choice. Metal domes are made from stainless steel, and have various different coating options that affect the resistance. These domes, once used with a flex circuit, PCB (printed circuit board), or membrane switch become open tactile switches. Here at SiTech, we offer the installation of these domes using a metal dome array, which is a double-sided adhesive that holds the metal domes. These adhesive sheets can peel away from a liner and be used to precisely attach all of the domes to the circuit. There are four main types of metal domes, they include: Circuit, Four-Leg,Four leg metal dome with center hole, Triangle and Oblong.
Circle metal domes look exactly like they sound, these are sometimes called round metal domes or circle tactile domes. Circle domes work great in applications that require a low profile switch under a membrane overlay. Circle domes can have longer life cycles than triangle domes, but relatively the same cost. The typical size of a circle dome is from 3mm to 20mm in diameter and the range of force is usually 100-60 gf.
The next type of dome is the four-leg metal dome, sometimes called cross metal dome. These domes were designed specifically for use where traces of positive and negatives can be designed under the dome on the same side of the circuit. Four-leg domes have a better clicking feel than circle and oblong domes. Circle domes typically have longer life cycles than triangle domes averaging approximately >= 1 million actuations. Four-leg domes are the tallest of the domes and are not to be used in low-profile applications. Generally Four-leg domes come in a 5mm-20mm range of size, and a 125-500 gf range of force