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I'm designing an enclosure for a device with a push button switch. The external button on the enclosure is physically large so I am concerned people will apply too much force and break the switch or break the switch off the board (if it's a right angle push button switch).

Most push button switches either have to be bottomed out or have a small widow where they are active so it doesn't seem like I can design the enclosure to ensure the user can always activate the switch but not allow the user to bottom out or over travel the switch.

I realize this is in someways a mechanical question but in other ways it's a question about the robustness of switches and I'm not finding much information on this.

How do I design for a push button momentary switch or what switch do I use to ensure that the user won't break it?

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  • \$\begingroup\$ You can use some military-grade buttons.. But these are expensive. \$\endgroup\$ – Eugene Sh. Jul 19 '19 at 19:43
  • \$\begingroup\$ put a spring between the button and the switch? \$\endgroup\$ – Hearth Jul 19 '19 at 19:51
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    \$\begingroup\$ Look for "vandal resistant switches" - these have definite stops that prevent overtravel - but most are panel mount to avoid the forces being transferred to the board. \$\endgroup\$ – Phil G Jul 19 '19 at 19:52
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    \$\begingroup\$ If the switch is right-angle to the board, and you are concerned about force, I would not mount it to the board at all. Panel mount a switch and use a connector to the board. This takes the stress relief off of the board and connectors itself. \$\endgroup\$ – Ron Beyer Jul 19 '19 at 20:38
  • \$\begingroup\$ You have a mechanical pushbutton, that bottoms out in its own housing, which activates a separate switch. \$\endgroup\$ – Neil_UK Jul 19 '19 at 20:59
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Arcade games have pretty robust switches, maybe start there. Crossing signal switches are another place to look.

A general approach would be to use a separate mechanical button with tough design that actuated the separate switch.

You could also use an optical proximity type behind gorilla glass if tactile feedback isn’t needed. Or use a light pipe behind a tough panel to do the same thing (I’ve seen crossing signals like this.)

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  • \$\begingroup\$ We used to purchase arcade buttons and switches for the Museum displays that we used to make. Check out "Happ Controls". I think they may have been purchased by another company but they still have all of the arcade stuff available. \$\endgroup\$ – Dwayne Reid Jul 19 '19 at 23:01
  • \$\begingroup\$ I have a design with the external button having a hard stop to prevent switch damage, but my problem is that many switches have little to no over travel. So far example it activates by 2mm minimum 3 mm maximum and no overtravel, so it's impossible to ensure you activate the switch and simultaneous ensure you don't apply excess force to the switch, so I'm wondering if I'm missing something. Maybe the just have enough flex and robustness to handle it if they have board alignment pins etc. capactive/prox is too power intensive for this application. \$\endgroup\$ – Josh Wales Jul 22 '19 at 16:08
  • \$\begingroup\$ hacktastical, could you clarify what a crossing signal switch is? I tried looking it up to no avail. \$\endgroup\$ – Josh Wales Jul 24 '19 at 13:01
  • \$\begingroup\$ A signal for a pedestrian crosswalk. \$\endgroup\$ – hacktastical Jul 24 '19 at 17:50
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Either mount the button to the chassis and use flexible wiring to the PCB, or mount the PCB so it is supported at one corner by the switch and can move sufficiently to absorb the maximum deformation that can be passed through the switch.

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