Switch lifetime
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Keyboard switches do not last forever.
Contact resistance[edit | edit source]
An ideal switch has infinite resistance when open, and no resistance when closed. In reality, the switch will always offer a certain amount of resistance even when new. Some manufacturers cite the contact resistance when new, and at the end of the switch's rated lifetime.
| Switch/series | Type | Resistance (new) | Resistance (end of life) | Rated life at rated load |
|---|---|---|---|---|
| RAFI RS 76 M | Crosspoint | ≤ 100 mΩ | ≤ 3 Ω | ≥ 10 million |
| RAFI RS 76 M (illuminated) | Bridge contact | ≤ 200 mΩ | ≤ 3 Ω | ≥ 100 thousand |
| Clare-Pendar Series S820 | Reed | ≤ 200 mΩ | ≤ 1 Ω | 5 million |
| Clare-Pendar Series S880 | Reed | ≤ 300 mΩ | ≤ 1 Ω | 100 million |
| Futaba MD-4P | Metal leaf | ≤ 100 mΩ | ≤ 5 Ω | 10 million |
Contact bounce[edit | edit source]
The contact bounce time for a switch increases with use.
| Switch/series | Type | Bounce time (new) | Bounce time (end of life) | Rated life at rated load |
|---|---|---|---|---|
| Futaba MD-4P | Metal leaf | ≤ 2 ms | ≤ 5 ms | 10 million |
