Electrolytic capacitor remains popular in power supply owing toto its lower cost. At extreme low temperature (105 degrees Celsius) electrolytic capacitors lost its capacitance by decrease and increase of leakage currents.
Hi Bashir
first of all, consider the specific application: for example,if you converter is a PFC stage in 230V mains and the capacitor is the input filter, you dont have to worry about leakege current; electrolytic capacitor is the first choice as it has high CV ratio, but if you have to manage less than -20C, you should consider foil capacitors (polypropilene or similar) or AEC-Q2000 components (may go down to -55C or up to +150). Nichicon products, as Ivan pointed out ,are good; consider also Epcos. On the contrary foils capacitors have a limit in high temperature +70Deg ambient, +85 Hot spot.
Ceramics based components con reach +200C but not for power applications.
So, if your design has to comply with such a wide temperature range, maybe you dont have a tight money budget and you can contact a capacitor supplier (Epcos, Murata, Icar) to develop the right capacitor for your application.
Hi, I would suggest a ceramic capacitor, even knowning that the capacitance of those is a function of temperature. The other choice would be a foil, polypropylene capacitor, but I do not know the temperature behaviour of those. I would definetely skim electrolytes as they are sensitive to elevated temperatures and dry out.
You should state operating voltage an temperature range. There is electrolytics going down to -55C however you must derate ripple current due to increased ESR. There are also automotive versions going up to +150C. Polypropylene (PP) film are specified to +105C hotspot with a derating in voltage.
polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyphenylene sulphide (PPS) typically goes to 125C.
Outside this range there is ceramics, however as they are quite brittle there may be problem with differing thermal expansion.
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If you are designing a product, you need to weight many parameters: performance, cost, size. Without knowing the exact specification, it is difficult to know how to weigh all of those parameters. The lifetime of an E-cap typically decreases a factor of 2 for each 10degC increase. that temperature applies to the hot-spot of the capacitor which will be often be in the center of the capacitor. Ripple current can significantly raise that temperature. So you need to know the ripple current and ESR to calculate the losses in the capacitor. Keeping the ripple current losses low will increase the lifetime. Using 125C caps will also increase the lifetime (as well as cost and space). There is no free lunch regarding increasing the lifetime -- it will increase the price and space required.
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