Why doesn’t the metal dome pop up when pressed？

Why doesn’t the metal dome pop up when pressed?

The metal dome cannot bounce back when pressed, which is also called the metal dome dead key phenomenon. This is fatal to the metal dome and directly causes the entire product not to work properly. So why does the metal dome have a dead key phenomenon? Let’s simplify it below. Analyze it.

The reasons why the metal dome does not rebound may be as follows:

The metal dome reaches or exceeds the design life: the thickness of a conventional dome is 0.06mm, and its life is 500,000-1.5 million times (according to load requirements). When the life reaches or exceeds 2 times the design life, it is easy to cause the KEY to not rebound and die.

The design rebound value of the metal dome is lower than the special design value: the conventional design rebound value of the metal dome is ≧40gf. When it is lower than the special design value of 40gf, as the service life is extended and reaches the life limit, non-rebound death will occur. KEY phenomenon.

The metal dome bears more than 2 times the design load: the dome is made of rust steel, and its design thickness is generally in the [0.06-0.1mm] range. The conventional design load value is 100-300gf. When the dome bears more than the design load for a long time When it is 2 times, it is easy to cause no rebound.

The metal dome bends due to external force: When the release film of the dome patch is torn off before attaching to the PCB board, or when the dome patch is produced, the metal dome is bent during the operation, causing damage or creases to the metal dome, or due to External force changes the concave structure of the metal dome itself, which can easily cause the KEY to die without rebounding.

The metal dome is not designed with ventilation slots: the air cannot be discharged during the stroke of the metal dome, causing the load to be unable to press and form a dead key phenomenon.

When the design does not reserve a pre-pressure stroke, the silicone or plastic guide posts will act on the dome for a long time, causing the metal dome to become heavy, and reducing the service life of the metal dome, causing a dead key or non-pressing function.