Benefits of IP 67 Approved Electronic Switches
A nice switch feel won’t matter much if the switch doesn’t work reliably for the life of the device.
The best tactile switches will typically offer a life expectancy measured from 100,000 to more than a million press-and-release cycles. Like force and travel specifications, the predicted lifecycle for every electronic switch is readily available on its datasheet.
Whether that switch reaches that lifecycle is another question. Tactile switches vary widely in their manufacturing quality and in their protection against liquids and other contaminants.
No Contaminants, No Problem. Understanding IP 67.
Since ingress of contaminants represents a key failure mode for switches, tactile switches for consumer and automotive applications increasingly need to meet IP 67 standards for protection against dust and liquid infiltration. Today’s wearable devices, for instance, nearly always require IP 67 tactile switches that withstand some exposure to sun screen, lotion and water.
Protecting tactile switches to IP 67 levels goes a long way to improving their lifespan, but there are typically trade-offs. Most suppliers implement IP 67 by adhesively bonding a silicone elastomeric membrane to the switch—between its interior metal dome and the exterior actuator button.
This arrangement effectively seals the switch, but the silicone makes the switch feel less crisp. If you compare two tactile switches with identical push forces, one with and one without the IP 67 membrane, the switch with the membrane will usually feel a bit spongy. The membrane approach to sealing switches also leaves the actuator at the top of the switch, exposing it to side loads, which can be another point of failure for tactile switches.
Maximize the Lifecycle of Your Electronic Switches.
The longevity provided by IP 67 typically outweighs the tradeoffs in switch feel, even with increased exposure to side loads. Yet it’s important to be aware of these tradeoffs when selecting tactile switches with a silicone membrane, especially if you’re trying to optimize for switch feel.
Another approach to sealing switches to IP 67 levels has emerged over the last year. Rather than bond a silicone membrane under the actuator, this new patented method laser welds a nylon-based thin film over the actuator. The new method has a clear edge over the traditional membrane construction when it comes to switch feel and protection from loads.
Whatever type of sealed switch you select, it’s important to realize that IP 67 rating does not mean that the switch is hermetically sealed all the way to the board. Nor does it mean the switch can go through a board washing process.
With those caveats in mind, though, IP 67 switches will typically last longer in the field. And if you pick them carefully, these switches can protect without sacrificing switch feel.
To learn more about tactile switches, download a FREE copy of "Improving Tactile Switch Actuation and Lifecycle" today. Click here.