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What's the best off-the-shelf solution for a vacuum encapsulation chamber?

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LAN_403

Scott Fusare

Wed Nov 04 2009, 11:48PM

Registered Member #531 Joined: Sat Feb 17 2007, 10:51AM
Location: Burlington, Vermont
Posts: 125

It's polycarbonate as I recall.

Don't think I ever got beyond replacing those two toothed timing belts on the harmonic drives. Always avoided the complete rebuild. I do have terrible memories of trying to remove one of them, I think it was the exit load lock, that was blocked by the "PLL" pump line on the 4600. What a mess, 10 lbs. of s**t in a 5 lbs. box, all caked in aluminum chloride and coiled in heating tape. Copper has obsoleted most of this I would assume...

What system are you working with? Each had it's own set of idiosyncrasies. Is Lam even supporting these things anymore?

What is the process you are trying to develop? I would think these etcher a bit "long in the tooth" for modern process'.

MinorityCarrier

Thu Nov 05 2009, 12:28AM

Registered Member #2123 Joined: Sat May 16 2009, 03:10AM
Location: Bend, Oregon
Posts: 312

Lexan is polycarbonate, so I was right.

It's a 4500, note the 100mm handler, so you know where we are technologically. LAM still supports them, but we had to buy a site license for the Envision O.S. or they wouldn't talk to us.

Copper Damascene/CMP is used for the small stuff, companies like Microchip and Linear Technology still use Aluminum.

I was responsible for a TCP9600 at a previous company. That was a good etch tool as long as the VAT pendulum valve didn't get fouled with AlCl3 and we changed out the quartz DSQ chamber every 6 months. The water vapor DSQ passivation process was a pile of poo, I went back to CF4/O2 plasma passivation which is kinda harsh on quartz.

Anyway, jpsmith, here's some real-world examples of thick transparent plastic vacuum chamber covers. They really do work well.

klugesmith

Thu Nov 05 2009, 02:50AM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1714

MinorityCarrier wrote ...
Here's a photo of the plastic loadlock cover for a LAM Rainbow etcher. The plastic cover is 32mm or 7/8" thick.

Sorry, I'm trying to butt out. But jpsmith asked about the actual thickness -- is it 32mm or 7/8" (22mm)?
Deflection goes as the inverse cube of thickness, so it matters.
Respectfully,
Rich F.

MinorityCarrier

Thu Nov 05 2009, 04:18AM

Registered Member #2123 Joined: Sat May 16 2009, 03:10AM
Location: Bend, Oregon
Posts: 312

22mm. Typing too fast and sloppy again.

Voltwad

Thu Nov 05 2009, 05:24AM

Registered Member #1829 Joined: Sun Nov 30 2008, 01:06AM
Location: Raleigh N.C.
Posts: 74

This seems an appropriate thread for my vac setup. It's a ~1/2 gallon glass cookie jar from target. Over that is a larger, clear polycarb jar just in case. They both sit upside down on a base. The base is a 1/2 inch thick polyethylene cutting board from target with holes drilled and tapped for some fittings. The gasket is some foamy sort of shelf lining, also from target. The whole setup, including a $15 water aspirator from cole parmer was less than $40. Using an overturned vessel on a base, as opposed to a pot with a lid may not scale up beyond a gallon or so, (not with glass anyway) but my aspirator goes to ~28 in. Hg with no problem so far and a clear vessel all round gives a better perspective than just a window or a clear lid I think. Just be careful when using glass you know. I wonder if there'd be a significant difference in stress between the pressures created by a water aspirator vs. a vane pump.

jpsmith123

Fri Nov 06 2009, 04:51PM

Registered Member #1321 Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843

The Vollrath stock pot came today, and with the exception of one small rough spot on the rim, I have to say it's a nice looking vessel. It's 10" ID and about 10.3" OD.

As far as the plastic cover goes, although calculations show that 0.5" thick acrylic or polycarbonate would work (i.e., the stress would be below the flexural strength limit by about a factor of 10 or so), the unknown factor is the loss of strength that will result from the hole I will have to drill in the cover to connect the vacuum system; thus I've decided to go with the 0.75" acrylic, which, if undrilled would present a safety factor of over 20.

IntraWinding

Sat Nov 07 2009, 02:30AM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

Could you drill the stock pot instead of the plastic?

Voltwad

Sat Nov 07 2009, 02:41PM

Registered Member #1829 Joined: Sun Nov 30 2008, 01:06AM
Location: Raleigh N.C.
Posts: 74

I actually built a similar device to use my aspirator to draw hot wort into a boiling pot from a mash tank. It was a 30 qt. pot and a 16" x 16" x 1/4" piece of polycarb. I couldn't get the holes drilled and tapped without crazing. Then I got a large polyethylene cutting board. That's much easier to tap, and stronger and more flexible. I then cut a large hole in the board and glued a piece of lexan over it for a window.

ConKbot of Doom

Tue Nov 17 2009, 02:23PM

Registered Member #509 Joined: Sat Feb 10 2007, 07:02AM
Location:
Posts: 329

We splurged and got a 12"x18" tall pyrex bell jar here at work for vacuum potting. It works well, with the pump we have it goes down to around 2 torr. Our potting specified to be degassed at 1-5 torr, which I found suprisingly low for how thin (non viscous) it is.
We had one of those lexan bell jars... its now my trash can, the flat of the top would suck down 3-4" and would be generally unnerving to use, even with the small dainty pumps we used to have. Definitely not on the cheap, but nice and effective.

The 3/4" acrylic/poly sounds like it should work better though, the edges of my trashcan/poly bell jar is only 1/8" and my calibrated finger calipers say the top is about the same too

Bored Chemist

Tue Nov 17 2009, 06:18PM

Registered Member #193 Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022

If it's big enough you might want to get thepolycarb jar out of the trashcan and use it as an implosion shield.
If the glass belljar breaks it won't be pretty.

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