High Temperature Electronics -300C to 500C

'Entering' in to high temperature electronics could harm you

Pl. be specific.

Dear Shyam

You should offer an incentive to disclose ideas on how to make sensors work inside high temperature environments. May be that in India the intellectual property issues are not yet important, as it is the general case in Asia, where the lack of protection incentives conspires against the creativity of Asians themselves.

But here this issue is becoming increasingly important to stimulate creativity and entrepreneurship, especially when you have already invested a lost of money and long hours of desperation solving real world problems with the constant threat of losing your best client.

Jaime Soto Figueroa

http://www.matharts.cl/

Dear Jaime Soto Figueroa

I am here on earth for just another 20 years. I have enough to keep feeding me for that much time. I have no wish to carry anything with me after I leave my this body. Losing something does not worrry me. It is worth talking and let many more men on earth share the knowledge and let them help each other. That is where I will be happy. My doors are open for people 24-hours and many keep coming each day. God could have made me dumb but he decided me to be the way I am, so I am the way he wanted me to be. I am friend of the people of my world. Losing is much greater happiness than anything I ever get.

Thanks for nice words but then I am Shyam.

Keep all Electronics only below +50 degee C .

Sensors at hi temp- naturally.

UseThermocouples/RTD/Thermistor -- which are 100 years old .

Sir,

You need to investigate SiC (Silicon Carbide)

components for high temperatures. Google SiC.

I have already done many high temperature work and do have 900C working transistors made of diamond with 5eV band gap. I also use these in radiation detection as these are not sensitive to dust or light and need minimum 250nm UV to trigger them. Idea is to get the entire process working for 300C to 500C range, which means crystal oscillator, resistance, capacitors, uC, memories, amplifier, analog mux, FPGA, and also battery to survive at 300C to 500C range. I am already having all these parts for 300C now but going to 500C is getting into problem. Difficult areas are crystals and batteries. Making few things to work at 900C is very much possible. I am not sure the way I can supply power to the circuit at that temperature. Do you have any idea? Perhaps a radioactive beta source battery?

Quartz crystals will be a problem at temperatures so close to the Curie temperature - subject them to the slightest strain and they will twin. It's worth considering some Quartz homeotypes, however. The Russians and the French have been quite active here. You will find some references in the Frequency Control Symposia (available to members of the IEEE's UFFC society - which I'm not currently, so I can't be much more help here).

If you don't need this level of precision, you might consider vibrating silicon (~30-ppm/degC, I think).

Vibrating silicon is also good for pressure sensing, and coupling using electrical fields is temperature insensitive (the etch process is often defined using quite heavy doping, so you can treat the silicon as conductive over the full temperature range). This is another field where I am not currently active.

I have no ideas about batteries, but imagine they will be very difficult. Certainly, none of the usual chemistries will be suitable, as they are mainly water-based.

Inductive transfer of energy will still work at these temperatures, but again the usual ferromagnetic materials are useless. I've seen reports of 300-degree operation, and indications of potential capability to 400-degrees, but that is all.
However, you could use higher frequency resonant air-cored transfer if there are not too many other losses.

If there is any way that you can physically connect to the outside world (wires, fibre optics) and minimise the power you need at the sensor level, that would be least bad...

I'll be interested to watch how this develops.

Regards

Fyz

Shyam

Other people have used RF induction to deliver power to a high temperature sensor circuit

Regards

Mike Manning

Yes RF induction now can be easily used as we have most of the ICs designed to take large ESD shock. Generally input stage which works at pA current level gets damaged. Other damage can be inductive pick up in the chip bonding wires. These form inductive loops and can easily generate a lots of voltages inside the chip where it is likely to be fatal for the chip. I did some experiments on ESD testing and inductive damages in chips 30 years ago and results were shocking. Others who did not know were damaging their very expensive equipments. I could design very better instruments which could take to large ESD. Now lots of chips come with protection up to 15kV.

Valves are better in many sense as they take take temperature and are almost insensitive to ESD. Remember the story of Russian Fox bat fighter aircraft? This one was fully built on valves and Americans Intelligence who planned to smuggle and strip open it were shocked of foul play. American once again was shocked to understand many years later of why it was built that way.

Some one designed a valves in a chip and it was a wonderful idea. It is somewhat similar to quantum dot cavity that was used to have a property of valve volume or vacuum in a chip rather than semiconductor. It consumed more space, but worked much better. Cavity was that of SiO2.

Some years ago I was involved in two development projects involving vibration measurement. One required contiuous operation at 200C with transients to 300C using silicon on saphire. The second was a sensor for operation at 500C which used silicon carbide. The sensing element was a piezoelectic crystal. Both projects were completed successfully.

At that time it was, and I'm sure may still be, a difficult problem. It is very much dependent on what you are measuring, the sensing element and the rate of change etc. in the operating environment in which it is measured. We worked with Honeywell on the first project and they were quite helpful.

I would be interested in learning more about your project and what the end use is.

To the Guest,

With respect to your comment:

"We worked with Honeywell on the first project and they were quite helpful"

I am very interested in who you worked with at Honeywell. Can you

give me a name and phone? Thank you.

Ed Rossiter

edrossiter2@aol.com

500C ultrasonic transducer is a very good idea. How much was the life of this transducer under continuous operation? I may be interested in the technology. I am looking for some under molten Sodium metal ultrasonic scanner or pressurized water high temperature environment ultrasound scanner. These applications are close to what you have worked on.

It depends what you wish to measure. Fibre-optics sensors are good up to these temperatures if operated at a suitable wavelength, but have limited capability operating on their own. SiC operates fine at these temperatures, but you have to live with the lifetime of the contacting materials - even an hour at 500C may means you need to select the material.
You will also find additional corrosive substances in many such high-temperature environments.

I agree. I will prefer to have temperature, pressure sensors made out of quanrtz or fuzed silica which can take 900C easily. It also allows us to work with UV. This a very good point. There is a great future for this technology.

Can you think on high temperature power sources? Will inductive transfer of energy work at 500C? What we need is only few watts of energy in and out.