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Look at the picture of my teardown of the SP10T I ordered quite a while ago from DigiKey, https://www.ckswitches.com/media/1349/arotary.pdf. Opening it, it's got grease on the contacts. Much more on the base side too, which is the second picture (a red circle points out one of the contacts that has a dab of the grease).

Of course, despite the clear color, it'd be crazy if the grease was a dielectric grease. That would hinder electrical conduction. It'd had to be conductive grease. But, scooping a bit of the grease & putting it on the tip of my multimeter's probes & only have the grease touch, I found out it is an insulator. It IS dielectric grease.

It's rated for 2.5A... Shouldn't the idea be maximizing contact to keep relatively high currents?

So what gives? Why would the manufacturer put insulating lubricant on the contacts?

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It's insulating, but enough of the large (for 2.5A) contact surfaces will make contact through the grease to conduct properly. The grease serves to keep debris off of the contact surfaces and prevent corrosion, which is in fact how dielectric grease is normally used.

Also, conductive grease could cause problems in an application that smears it between contacts, possibly making a bridge.

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  • \$\begingroup\$ Yeah, your second paragraph I already knew. \$\endgroup\$ Commented Mar 29 at 9:04
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It’s silicone grease. The reason they put it in the switch is for lubrication. Moving parts tend to need lubrication to reduce wear and make them easier to move.

That the grease is not conductive has little if any affect on the contact resistance, there is enough pressure to get a good metal to metal contact. In fact you don’t want it to be conductive as that would cause leakage currents between the contacts.

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