Potting Compound

Can you provide more information please (such as the application, fluid temperature range and a physical description of the temperature sensor). Standard potting compounds and conformal coatings are not going to be suitable if you want rapid thermal response or if you are measuring hot engine oil!

As far as the application, I am measuring a fluid that is an oxidizer and is corrosive and is being stored outside. The measurement will be taken at the core of a 55 gallon drum of the fluid. Rapid thermal response time is not critical as the only factor that causes change in the temperature is the ambient outside temp (in the mid-west US), and that cannot change the temperature at the core very quickly. That should also answer your question about the temperature range. Physical description, the best I can do is tell you its a small 4 pin surface mount semiconductor chip(sorry, I do not have the specs), mounted to a pcb roughly .500 x .600, with 6 pins for what appears to be a "socket" installation. Hope this helps.

Thanks. Sounds like a job for some type of 2 part epoxy. Maybe filled with TiO₂.

I'd say J-B weld would work. (Not a product endorsement)

Without knowing what the fluid it and what the response he is looking and sensitivity to heat of the sensor hard to tell what will be good or bad.

In my world of electronic I always found single component potting compound is better than two components one and got so fascinated I started business of transforming the needs to one component glue to make electronic component and layed down foundation of company.

If you provide your needs I am sure will be able to recommend and provide you with sample free of charge

What is the fluid? Operating temperature? Exposure time? Any stress sensitive components (glass)

Emerson Cuming, Hysol, Loctite, National Starch, and many others can help, but they'll want to know all of the above and how many million gallons of it do you want?

Loctite says their single component potting works well. I'd use somebodys epoxy, myself.

Whatever you use, try to cure it at the operating temperature. Then, in service there won't be much stress on the part.

Good luck.

I would recommend checking out Master Bond. They tend to have great technical service and deal better with low volume requests in my opinion.

http://www.masterbond.com/produse/produse_tc.html

You also have options of using a thermally conductive filled plastic or even better copper/brass probe depending on design flexibility. Take a look at some water heater or oil/coolant temp sensors for some ideas.

Good Luck!

I have spoken with Master Bond and they are sending me samples of 2 different products. 1 is a 2 part mix and the other is a "dip". Thanks

Take my advise. I have potted more stuff then I would care to remember. Call these guys. Super nice guy and VERY knowledgeable!

Tom Daggy
United Resin Corp.
2622 N. Ogden
Suite 105
Mesa, AZ. 85215
Office: 480-830-3200
Fax: 480-830-9151
CA. Cell: 714-585-1037
AZ. Cell: 480-221-2945
www.unitedresincorp.com

Just my recomendation. I dont work for them or anything! hahaha! They guy has just saved my butt more than once!

Bill12780

"Conformal Coating" will do the trick for you.

I quote from http://en.wikipedia.org/wiki/Conformal_coating-" Conformal coating material is applied to electronic circuitry to act as protection against moisture, dust, chemicals, and temperature extremes that if uncoated (non-protected) could result in a complete failure of the electronic system."

RTV potting compounds are good, they cure at room temperature & are soft enough to be cut out if you ever need to repair the PCB. The one in the link is thermally conductive.

The ultimate coating is Parylene, this is deposited as a vapour so you would need to sub-contract the operation which may not suit you. Parylene gets into every gap, even underneath soldered components but is only microns thick.

I was working for a SPA controls manufacturer and we used 2:1 epoxy resin, the same grade of epoxy use for marine construction like fiberglass-epoxy hulls, fiberglass-epoxy canoes, etc ... We put the sensor in a stainless steel container, the container must be as small as possible to fit with the PCB size and fill it with 2:1 epoxy resin.

A lot depends on variables that you have not provided.What is the temperature range of the liquid?What is the liquid?How fast do you need to respond to temperature changes?

These will all affect the choice of sensor and the covering of it.If a very quick response is not neede, a thermowell will do.If very quick respo0nse is needed, a low-mass thermocouple will be required.

If the fluid is non-condcuctive, no insulation may be required, depending on the fluid characteristics.

Please provide more info.

Selection of potty compond depends on what fluid you have. If your fluid is not based on acetone I can provide you free sample of potty compound which is clear and will overcoat and will not stress the board or component on board

This potty compound is easy to remove if you need to rework and then you can always repply