Hermetic connectors

I've seen that done--quite a few semiconductor tools do it. You use an O-ring Dutchman flange, just like putting in a window. The board will need some stiffening, e.g. make it 3-5 mm thick depending on the flange diameter. A bit of Dow grease on the O-ring will fix the surface roughness problem.

Cheers

Phil Hobbs

Nice idea. You could epoxy the PCB to a metal flange, too, something with a standard bolt pattern.

FR4 is strong. They make Corvettes and speedboats out of fiberglas.

Okay, I'll bite. What's a "Dutchman flange" in this context? Doesn't seem to be any in my Lesker catalog. ;-)

I forget the proper name for them. They bolt together like a Conflat, but use O-rings instead of knife-edge seals and about half as many screws.

Cheers

Phil Hobbs

I was thinking of just having an O-ring groove in the mounting piece of metal and then screw holes in the pcb. (one less piece of metal.)

George H.

I figured he meant something like is done with optical windows. O-ring grrove, window, and metal ring that bolts over the window and presses it into the O-ring.

As I said to JL I was just picturing bolt holes right in the pcb, maybe with some washers to spread the force some more.

George H.

Hey Spehro, as long as I have your attention. I tried soldering the connector body to the pcb.

There's ~ 40 mil gap between the body and the pcb because of the plastic support.

I was wondering if just the 8 pins on the connector would be enough to stop it rotating. (OK I'm picturing some burly student turning it the wrong way. so maybe not.)

George h.

I've seen this done across a 7PSI barrier (ambient on one side, nitrogen- purged and pressure relieved to 7PSI on the other). It works pretty well.

It'll probably work better if you don't put solder mask on the vacuum side, and leave it mostly bare copper. A bit of metal retards gas diffusion amazingly.

Cheers

Phil Hobbs

We use T&E for custom glass sealed feedthru's. But for a quick sealed connector you can solder single lead terminals into a copper plate

Cheers

No I need a connector... that students will use. Sometimes they don't know which way is on or off, and they just keep turning till it breaks.. We then have to repair it... I think we're lucky if we break even on repairs. It's much better if it never breaks...

"Yeah good luck with that George."

George H.

Thanks, Re: T&E can you say how much you pay.. is it less than $100

"Ohhh Nooo Mr. Phil!!!" I'm going to have to find the vapor pressure of solder mask. (excuse the Mr. channeling SNL :)

I was thinking lots of copper and a solder mask with the two part solution (connector in atm. traces next to O-ring) Filling in the valleys.

The single hole is cleaner. Maybe the best thing would be a connector into a surface mount terminal block. (on the vacuum side.) That way the down hole wire can be changed. And the whole wire harness would go away.

Anyone use a good surface mount terminal block? I like the machined contacts from Phoenix contacts in through hole.

George H.

You should consider using mini-DIN connectors with extra sealant. They'll work perfectly.

On Tue, 16 Jun 2015 03:15:01 +0000 (UTC), Cydrome Leader Gave us:

snip

Excellent suggestion. Micro D is a good choice too.

I've seen D connectors with glass/metal feedthroughs, with solderable tinned shells. Also BNC connectors with O-rings and glass/metal seals.

"glass metal seal D connector" pulls up lots of hits.

People who should know say that the ceramic seals are even better...

I have used Delphi Weatherpack wire-mount connectors before, but they are "sealed" in automotive terms - against water, coolant, oil, etc. Dunno how well they do in vacuum, or how well the pricing meets your needs. The nameplate rating is 16 V, 20 A per circuit. IME they are pretty serious about the current rating, but you can go a little over the voltage rating (at least in air) without undue mayhem.

The ones I used were 1 to 6 pin housings that went on wires; kits of everything you need for these are easy to find. You can also get bulkhead versions, such as

They are definitely labor-intensive. For each wire, you get to install the seal, strip the wire, crimp the terminal, and then poke the terminal into the right cavity in the housing. There is also usually a retainer that clips on the housing after all the wires are in.

The rubber seals that go on each wire seem to come with a little bit of mold release or oil or something on them. You may need to check that this is compatible with your vacuum.

If you're doing one or two wires, total, you can get there with whatever crimp tool / needle-nose pliers you already have lying around, but if you're doing more than that, it's worth it to get the "official" manual crimp tool, or maybe the "official" ratchet crimp tool.

The keying seems to be pretty robust, and if you manage to screw up one pin, you can replace just that one, instead of the whole connector.

Matt Roberds

I've got some vertical DE9 sockets that would suit that application well. 2 sided pcb wth through-hole plating to mount the connector and solder to seal. another DE9 connector on the inside either soldered to the tips of the pins or mounted through-hole offset to allow soldering.

that stuff is pretty tough. if the area is 4 square inches it only needs to withstand 56 pounds, which is about as hard as I can comfortably press with my thumb, I can't see my thumb going through a

On Tue, 16 Jun 2015 07:59:56 +0000 (UTC), snipped-for-privacy@att.net Gave us:

You could use single hermetic conductor pass thrus for each wire, then put a connector *inside* the chamber for ease of attachment. (and outside too). That way, you are SURE it is sealed. They even come threaded and you can seal the threads with a suitable 'hard' epoxy.

Then the connectorization 'system' itself can be as cheap as you like.

On 16 Jun 2015 08:06:36 GMT, Jasen Betts Gave us:

You can buy a BLOCK of "G10". Then drill it, run wires, seal them. Why cut up the chamber wall though. Use single hermetic pass thus and put a cheap connector system INSIDE the chamber. Then you only need to drill some holes for each wire, thread the holes and place the pass thrus.