Metal dome is a kind of small button made of metal material. It's conductive, and it's convex in shape. Metal dome can't be fixed on something by itself. It's slow to install a single one on printed circuit board, and it is not stable. A fixed medium is required at this time.

There are some ways to install metal dome, such as gluing, tying with iron wire, directly making a clip on the board to stick it in. You can also weld it, or use a special sticker. These can all get the job done, but which one is available for PCB? Let's talk about it.

Glue

We all know that glue can fix things, especially strong glue, which can firmly fix many things together. But can it fix metal dome to the PCB?

Metal dome takes advantage of the conductivity of metal materials. It undergoes some industrial production processes, such as stamping, to make it have stable rebound strength. When you need to press it to conduct electricity, it's conductive.

When the strong glue is pasted on metal dome, it forms a layer of colloid. It plays an insulating effect, especially when the voltage is very small. And the conductivity will be lost. Glue is out.

Iron wire

What about iron wire? Metal dome needs current, we press it down to let current pass. When we don't need it, we release it so that there's no current. However, if we tie the metal dome with iron wire, it will become difficult to press under the force of the wire. In other words, metal dome will always be conductive even if it is not pressed. That's the point. The constant conductive state ruins everything.

Clip

The clips are designed on the PCB board to fix metal domes. They basically are not harmful. But there is one thing, this design will increase the thickness, which may be difficult to apply on products. It will also increase the cost.

Welding

What about welding? Triangular metal dome with legs only needs two leg holes on the board. The welding will be good. Cross-shaped metal dome has four legs. You can just weld the legs. Metal domes generally will not move. You can get what you want.

On the other hand, welding is hard. You can't weld too much on the four legs. If there are only two or three metal domes on the PCB, it'll work. If there are more than a dozen, it must be very labor-intensive. The cost is not worth it.

Special sticker

Let's talk about special sticker. Use stickers to design the slots one by one and then insert the metal domes into them. This solves the fixing problem, and also perfectly improves the assembly. There are many kinds of stickers today, single-layer, double-layer, silver-plated paste, white stickers, etc. The size of each sticker, and the number and position of fixed metal domes are not the same. People make molds of printed circuit boards.

Metal domes and dust

Will dust go into metal dome? It's up to the assembly. For example, triangular metal dome with feet is usually fixed with two slots on the printed circuit board. When being pressed, dust can easily enter the concave surface through the two slots, causing poor conduction.

Improper design of metal dome may also cause dust to enter. For example, if it is too close to the edge, it easily pushes up the PET. During the pressing, dust will also easily enter the concave surface, causing poor conduction.