I am designing a flyback converter that needs to placed inside of an oil tank. My question is how would a opto-coupler survive in oil. I have seen that some fluxes can cause infintile failues.

Dan,

Your best bet is to contact the manufacturers and let them know what type of media the device will be immersed in, the operating conditions (time, temperature, ph, etc.), and let them offer the correct part number to you. They know their product better best, or they may have an alternative solution to your problem.

Alan

Alan,

I have contacted the manufacturer of the part and they said its not tested in that environment and cannot say how the part is affected. I have started testing a circuit in oil and have 12 hours of run time with good success, but I am concerned with the long term affects of the oil.

Depending on the type you use, oil has capacitance. You may want to model your circuits using the capacitance range with the tank grounded reference. The rest of your R&D will depend on analysis of the field effect produced by HV of fly-back converter circuit. Can you shed more light on the kind of failure you are referring to?

Adebuyi,

At my company we have found that opto couplers are not sealed devices and can be damaged by halide flux will cause infantile failures due the flux coating the internal optics. I am trying to understand if oil will have the same kind of affect on the device.

Thanks,
Dan

If there are inherent established doubts regarding safe use of inverters immersed in oil, why not try other cooling options.

The customer spec does not allow for air cooling and the COGs does not allow for use of SOT packages for switches for the system. Oil cooling provides a cheap alternative.

As professional engineers we should not encourage unsafe cheap options as it may turn out to be penny wise pounds fool. Under the given circumstances, you may share the details of insulation and other materials proposed to be used in your converter, and the environments of its placement with the oil manufacturer, who may be in a position to provide oil best suited for your converter.