Date: Mon, 30 Sep 1996 09:05:49 -0500 From: Mark Stephens To: Multiple recipients of list Subject: Liquid N2 temps and 68HC11 Anybody have experience using the 68HC11 (or any micro) at liquid nitrogen temps? I don't know exactly how cold that is, but it's damn cold. The chips would be placed in close proximity to a dewar cooled by liquid N2 to handle temperature sensors. thanks, mark mark stephens "In constraint, Goddard Space Flight Center is freedom" Code 521, Bld 23, Rm E441 Greenbelt, MD 20771 Date: Mon, 30 Sep 1996 09:41:04 -0500 From: B.M. Cook To: Multiple recipients of list Subject: Re: Liquid N2 temps and 68HC11 > Anybody have experience using the 68HC11 (or any micro) at liquid nitrogen > temps? I don't know exactly how cold that is, but it's damn cold. The > chips would be placed in close proximity to a dewar cooled by liquid N2 to > handle temperature sensors. In the past, Denis Nicole of Southampton University (UK) has placed CMOS processors (Transputers) INTO liquid N2 - they went about twice as fast as at room temperature :-) Barry. Date: Tue, 1 Oct 1996 01:57:06 -0500 From: Jaakko Koivuniemi To: Multiple recipients of list Subject: Re: Liquid N2 temps and 68HC11 > > > Anybody have experience using the 68HC11 (or any micro) at liquid nitrogen > > temps? I don't know exactly how cold that is, but it's damn cold. The > > chips would be placed in close proximity to a dewar cooled by liquid N2 to > > handle temperature sensors. > > In the past, Denis Nicole of Southampton University (UK) has placed > CMOS processors (Transputers) INTO liquid N2 - they went about twice > as fast as at room temperature :-) I haven't really needed MCUs at LN2 temperatures (77 K), but silicon FETs seem to operate better than at room temperature. One of our optical research groups is using CCD camera at 50 K for interferometry. Oh, 273 K = 0 C or freezing whatever that is in Farenheits. Some of the GaAs MESFET transistors work even at 0.05 K, but that is a different story. With bipolar transistors you may have a problem. Don't break the hc11 package in shock cooling. Then there are several other components needed for the hc11 to operate (crystal, power supply, RESET circuit, tantalum capacitors), which I don't really know how they work at LN2 temperatures. Good luck! -- Jaakko Koivuniemi Low Temperature Laboratory, Helsinki University of Technology Lab and vortices: http://boojum.hut.fi/ Jaakko: http://boojum.hut.fi/%7Ejaakko/ Date: Tue, 1 Oct 1996 10:58:04 -0500 From: Intec Inoventures Inc. To: Multiple recipients of list Subject: Re: Liquid N2 temps and 68HC11 >Anybody have experience using the 68HC11 (or any micro) at liquid nitrogen >temps? I don't know exactly how cold that is, but it's damn cold. The >chips would be placed in close proximity to a dewar cooled by liquid N2 to >handle temperature sensors. You may want to keep the HC11 out of the dewar flask. On the other hand, it would be an interesting experiment... Keep us informed if you decide to dip it. The HC11 is only rated down to -40C and liquid nitrogen boils at about -160C. Also, the air (assuming some ventilation) around the dewar will be quite cold, resulting in condensation; something you do not want on your board. The white "smoke" that you see around dry ice, liquid N2, etc. is just a very fine mist resulting from the cooling of moist air with which it comes in contact. Bfn Bob Furber -------------------------------------------------------------------- MC68HC16 Embedded Controllers and Software Development Tools | WebPg http://www.islandnet.com/~iii | -------------------------------------------------------------------- Intec Inoventures Inc. Phone 604-721-5150 | 2751 Arbutus Road Fax 721-4191 | Victoria BC V8N 5X7 | Canada | -------------------------------------------------------------------- Date: Tue, 1 Oct 1996 16:04:35 -0500 From: Frank Henriquez To: Multiple recipients of list Subject: Re: Liquid N2 temps and 68HC11 I've had some experience with LN2 temperatures. Most small components like resistors and NON-ELECTROLYTIC capacitors and even wire-wrap wire do just fine in a vacuum at temperatures as low as 35 - 40K. I have a few boards with IR arrays on them that have been going from room temperature to 70K and back for about 5 years, and the components look brand new. I've seen FETs and even op-amps working at 70K, but i think you'd have to hand pick those components. Some FETs and op-amps have a freeze-out temperature where they'll either stop working or actually get *noisier*. Some ICs will work just fine at LN2 temps, but I think size is a critical value - a large IC like the HC11 might crack if cooled or warmed too quickly. EPROMS (with quartz windows) might present other problems, too...since there'll be a trapped volume of gas in a vacuum. If the HC11 is placed outside but near the dewar, you will want it protected against humidity. The white mist produced by LN2 is everything from very cold nitrogen gas to liquid oxygen to condensed water vapor. Just make sure that no water vapor or condensation (even inside the component box) can short out the board. Frank -- Frank Henriquez UCLA Astronomy Department Date: Tue, 1 Oct 1996 21:01:43 -0500 From: Mark Wistey To: Multiple recipients of list Subject: Re: Liquid N2 temps and 68HC11 Jaakko Koivuniemi wrote: > Then there are several other components needed for the >hc11 to operate (crystal, power supply, RESET circuit, tantalum capacitors), >which I don't really know how they work at LN2 temperatures. Good luck! Back in materials class at Montana State (back when the buffalo were still called mastadons...) we talked about electronics used in an alpine winter environment (-50C). Crystals would break if jarred--when elk rubbed against the container. The electrolyte in electrolytic capacitors would freeze; aluminum caps would be less than 1% of their stated value, tantalum caps would be somewhat better. Resistors would vary widely depending on their materials. Transistor amplifiers would lose much of their gain because fewer electrons (or holes, for that matter) would have the thermal energy to jump into a free energy band. Basically, if you have control over the design, design for the cold temperatures. If you don't, try the board at 55K, see if it still works, then use it at 77K. :-) Definitely keep the power supply warm--those big caps don't do much good below -50C. Wow, it's been a long time since I got to play with this stuff. Thanks for the trip down memory lane... - Mark - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Mark Wistey Date: Wed, 2 Oct 1996 00:10:31 -0500 From: Keith Daniel To: Multiple recipients of list Subject: Re: Liquid N2 temps and 68HC11 >Jaakko Koivuniemi wrote: >> Then there are several other components needed for the... >Back in materials class at Montana State (back when the buffalo were still... Thanks! I'm involuntarily looking forward to my 37th consecutive Montreal winter, and we're building things for outdoor amateur radio. Thanks for the ECW discussion. 73 de VE2KXD kwd... Date: Wed, 2 Oct 1996 19:36:44 -0500 From: Marek B. Kaminski To: Multiple recipients of list Subject: Vacuum electronics??? Discussion of liquid nitrogen temperature applications reminded me that I will need to put lot of stuff in vacuum sooner or later. The stuff is interface / control electronics plus motors, rotary encoders etc. The vacuum is NOT cold, but rather deep (heavy ion accelerator). Yes, there is some gamma rays as well. Handbook level knowledge suggests obvious problems: - leaking electrolytic caps (power supply manufacturers love them, and their volume / capacity ratio is hard to beat), - overheating chips and motors, - exploding parts which have air bubbles trapped within. Our application specific problem is outgassing (releasing of gases) by hardware; usual solution is to bake the thing to expedite the process - but I'm afraid electronic components might be less than happy. Any ideas, please? Marek Kaminski, Australian National University, Canberra Date: Thu, 3 Oct 1996 02:10:05 -0500 From: Jaakko Koivuniemi To: Multiple recipients of list Subject: Re: Vacuum electronics??? > Discussion of liquid nitrogen temperature applications reminded me that > I will need to put lot of stuff in vacuum sooner or later. The stuff is > interface / control electronics plus motors, rotary encoders etc. The > vacuum is NOT cold, but rather deep (heavy ion accelerator). Yes, there > is some gamma rays as well. Handbook level knowledge suggests obvious > problems: > > - leaking electrolytic caps (power supply manufacturers love them, > and their volume / capacity ratio is hard to beat), > - overheating chips and motors, > - exploding parts which have air bubbles trapped within. > > Our application specific problem is outgassing (releasing of gases) by > hardware; usual solution is to bake the thing to expedite the process - > but I'm afraid electronic components might be less than happy. > > Any ideas, please? For me the problem seems similar to design of electronics used in satellites or other scientific space craft. There thermal considerations are even more important. Some plastics may even evaporate in vacuum conditions. Your vacuum can't be really "Ultra-High-Vacuum", since all the electronic mess would contaminate it badly. Once you get zinc into UHV, you will never get it out by pumping. I wouldn't put the electronics into vacuum unless it is really necessary. It will be a lot of work to test it and find the right materials. For the gamma rays and all other radiations - better to ask the space people. Gamma rays will penetrate easily into most materials and you need heavy lead shields to stop them. -- Jaakko Koivuniemi Low Temperature Laboratory, Helsinki University of Technology Lab and vortices: http://boojum.hut.fi/ Jaakko: http://boojum.hut.fi/%7Ejaakko/