Cable to switch covering - use RTV or something else?

I have a project that part of it is a double pole double throw switch. The connections go into a covered cable (CAT5) and then to a molded on connector. Wires are soldered onto the switch. Once assembled there is no need to get to the connections again.

I’m looking for ideas on how to close up the back of the switch and protect the pins. In the prototypes I used Silicon RTV to cover the 1/4" high pins. I bend the cable down so it comes out the end of the switch. RTV between the switch and cable to hold it down, and then more RTV to cover the pins. Due to my amazing lack of eye / hand coordination the RTV has bumps and swirls in it.

I need to create ~50 of these switch / cable combinations. I’m looking for something easy and simple to do that looks reasonably nice.

Switches are 1 1/4" by 1/2" and are slide switches. They do not have mounting holes on them so a case or a box adds a new layer of problems.

I thought of trying to use small icecube trays as a form, but I’m not sure that the RTV will pop out of them.

Thanks for your ideas!

Would heat shrink tubing work?

Normally I’d say hot-melt glue, but 50 of them?

If an ice-cube tray size is not too large, then you can use any of several substances, first choice in my mind would be liquid epoxy potting compound, just pour and wait. The downside is that it’s difficult to remove if repairs are ever needed.

To have any substance release easily from an ice-cube mold, use silicone spray liberally. This is how it is done in industry. An alternative would be to get a flexible silicone ice-cube tray so it can be peeled off instead (but still use the release spray!)

Silicone “caulk” is not an ideal substance. As part of the curing process it releases acetic acid (vinegar), which attacks electrical connections. In electronics, it is used only as a mechanical connector to hold heavy components in place on a PC Board, and should never come in contact with metal connections. You CAN buy silicone potting compound which uses a different chemistry and is safe for electronics, but it isn’t cheap.

If you do use epoxy, consider a custom mold that creates mounting ears for your switch, or some other mechanical features that will improve the device. Molds can be made from hard plastic (polyethelyene), metal, or even machinable wax (Google it, I use Freeman Supply for mine).

Good luck!

RTV is not a good idea to insulate electrical components, most formulations are corrosive to copper. If you do want to try an RTV make sure you find something that won’t cause corrosion and if you do I think the ice cube tray would be perfect. All the automotive formulations pop right out of the supplied extension tube when allowed to properly cure.

Another option to look into is the silicone used to make castings, don’t know if it will cause issues with corrosion or not. But it is designed to work with a release agent coating the part being replicated. I don’t see a reason the release agent couldn’t be applied to the ice cube tray.

The last option I can think of is to use a rubber based potting compound designed for circuit boards that will be located in high moisture environments.

How about epoxy putty?