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Figure 1. Relative Failure Rates for
Capacitors3
Capacitor failure rates vary considerably with style
and value. Variations are shown in Figure 1
for each capacitor style addressed in this section. Even within the same style,
capacitors have a wide variation in failure rate. Large value capacitors will
often be less reliable due to the increased physical size, larger anode/cathode
surface area, and the increased amount of dielectric material. Glass-style capacitors are considered the
most reliable, followed closely by ceramic. Variable capacitors are considerably
less reliable and should not be used in high reliability applications. If it is
necessary to compensate for temperature-capacitance effects, the preferred
method is to use capacitors of more than one style and take advantage of
property differences rather than using a variable capacitor.