Re: Testing under vacuum
 

Ive had a thermocouple welder on my acquisition list for quite awhile, but they aren't all that cheap on ebay generally, and its not a very high priority, its factory automation and control engineering where they are doing hundreds per year Id imagine that it comes in handy, but then Ive also seen thermocouple "kits" with SS probes\wells, mineral insulation, and of course sensors.

The advantage there is you fabricate grounded, ungrounded ect packages yourself, but typically the sensor itself is factory made and you connect to it (which is where Id use a welder)

While I have no real idea of specifically what the difference would be between simply a wrapped vs welded vs factory fabricated sensor
I would assume its a closer repeatability with less error rate. and that a wrapped solution is a "close enough" general temperature type approach. Handmade welded sensors if they where subsequently calibrated and the error factor was coded into the aquistion system Id imagine would approach the same fidelity as a factory manufactured sensor that is consistently made from unit to unit in a more controlled manner. Simply with less error to plot those are "close enough" out of the box Id gues by at least a decimal place or two. (6.5 DMM)

Just a little dead reckoning ;)

Re: Testing under vacuum
 

Looks rather simple, check out this oldie:
http://www.overclockers.com/tips437/

I'll make my own for the air measurements, for now.

This welder's insanely expensive:
http://www.tiptemp.com/Product.aspx?ProductID=4002
(TIG welder)

Another one, slightly cheaper:
http://thomasregister.com/olc/smartc...xtcolor=000000
with details here:
http://thomasregister.com/olc/17183047/twospec.htm
A 35 Vdc to 75 Vdc source, 250 Joules (watts/sec) capacitive discharge.

Re: Testing under vacuum
 

since Bill is away I guess I'll need to play devil's advocate :p

as you are of course aware, we are now talking pretty small differences in one DUT vs another, and Id imagine that even though the primary path would be whichever two thermocouple metals are employed some of the path would be through the solder. Id also want an "ungrounded" sensor for directly embedding in a heatsink and or multiple surface mounts

used welders on ebay run $200>300
"as is" nasty ones occassionally much cheaper, that would still buy one hell of alot of bare sensors

I bought 40 epoxy coated and 40 glass rod thermistors the other day planning on building some "grids" with them that can be installed infront of, in back of and inside of cases \ fans. I'd be able to do 50 channels at a time with the 7701 (would need to build 2 cables)

close enough for rock and roll is really a function of what it is undertest, measuring airflow Im just trying to get a basic picture, but in WB tests there are alot of "photo finishes" which I think demands as high an accuracy as can be managed, there are alot of unaddressed variables still, and the "general picture" pretty well mapped already

Re: Testing under vacuum
 

I like the way you think ;)

If I went the way of the solder (which still looks dubious to me), I would expect the solder to impact the response time of the TC, but otherwise nothing else. A big assumption...

I much, much favor the welding method, just because it's a simpler no-nonsense worry-free approach.

I just have to figure out something, somehow. We've posted links before, to spot welders. There's got to be an easy way to weld thermocouples. Google, here I come.

Re: Testing under vacuum
 

if you want to know my real fear
its that the embedded chip cooling technology will change before we are really able to find an agreed on proceedure, IHS is just the first step, Im not even sure "waterblocks" as we know them are going to be that relevant for too much longer. There are so many developing technologies from Diamond Substrate Chemical Vapor Disposition to Carbon Nano advances in materials to nano heatpumps, dual phase microchannel and spray cooling that with the ever greater increases in power I think we are going to see integral thermal solutions sold with CPUs sooner rather than later. Intel's "waterblock" system was just the first. The IHS is basically a heatpipe base, its currentlty transferring to a seperate component but for how much longer? I think there will be a trend for the IHS to "grow" into a larger interface, that attaches to something else, possibly several options of something else.

remember alot of what drives thermal issues chip development comes from incresing densities in 1U and now blade servers
but once tooled into the fab gets transfered to the desktop

thats why Im really more interested in being able to determine the power consumption and develop a system that measures the total amount of heat whatever tech that is applied is moving to the case (or outside the case)
my "waterblock" test suite is really looking more to that direction. And I see vacumm insulation as an important part of quantifiying and isolating variables.

Re: Testing under vacuum
 

Got'em:

http://www.5bears.com/welder.htm
and
http://users.frii.com/katana/spotweld.html

Re: Testing under vacuum
 

:p

you cant link that here without also linking this
http://www.5bears.com/cnc.htm

everything duely bookmarked ;)