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Behind The Mystery of Electromagnetic Compatibility Design 18 Lifetime Consideration The lifetime of electrolytic capacitors is very important in industrial applications and other applications requiring a high lifetime. Here, the capacitor is not used as a kind of predetermined breaking point (also called planned obsolescence) in consumer electronics but is a durable and reliable component. The life of a capacitor depends on many factors of the application. An important factor is a temperature or thermal load, which is responsible for the fact that internal structures age over time and the electrical properties deteriorate. This results in increased leakage current, increasing the ESR, which leads to a further increase of the temperature. The reason for the temperature increase is the power loss generated by the ESR. If these limits are not exceeded, high lifetime expectancies are possible when the inner temperature load of the component is in a lower range. A comparison of the lifetime of aluminum electrolytic and aluminum polymer capacitors by temperature load is listed here. The basis of this consideration are two formulas. With liquid electrolytic capacitors, the expected lifetime doubles when the temperature at the component is reduced by 10°C (2). For polymer electrolytic capacitors, life increases tenfold when the temperature at the component is reduced by 20°C (1). The formula for aluminum polymer capacitors: The formula for aluminum electrolytic capacitors: To further illustrate, the calculated lifetime values are shown in Table 2 such as temperature values. Here, the maximum specified component temperature is used to compare aluminum electrolytic and aluminum polymer capacitors. Table 2 shows lifetimes for both types. The application temperature is defined in formulas (1) and (2) as the ambient temperature T a . The hour's definition at 105°C in the first row for the aluminum polymer and the aluminum electrolytic capacitor is the nominal lifetime of the component L NOM . This is linked to the maximum specified temperature at the component and is defined as T 0 . The other hours in the second row are the calculated lifetimes L X using formulas (1) and (2). In the aluminum polymer capacitor column, the calculated lifetime is 2.000.000h at 65°C ambient temperature. This means a theoretical lifetime of 228 years. To guarantee such a lifetime is not possible. The typical maximum expected lifetime varies for different vendors and is between 13 and 15 years. Table 2: Lifetime overview with different ambient temperatures (Source: Würth Elektronik Group) Temp. (°C) Aluminum-Polymer-Capacitor (h) Aluminum-Electrolytic-Capacitor (h) 125 2.000 2.000 105 20.000 2.000 8.000 2.000 1.000 85 200.000 20.000 32.000 8.000 4.000 65 2.000.000 200.000 128.000 32.000 16.000 The capacitor is not used as a kind of predetermined breaking point (also called planned obsolescence) in consumer electronics but is a durable and reliable component. "