In ferroelectric Class 2 ceramic capacitors, capacitance decreases over time. This behavior is called "aging". This aging occurs in ferroelectric dielectrics, where domains of polarization in the dielectric contribute to the total polarization. Degradation of polarized domains in the dielectric decreases permittivity and therefore capacitance over time. The aging follows a logarithmic law. This defines the decrease of capacitance as constant percentage for a time decade after the soldering recovery time at a defined temperature, for example, in the period from 1 to 10 hours at 20 °C. As the law is logarithmic, the percentage loss of capacitance will twice between 1 h and 100 h and 3 times between 1 h and 1,000 h and so on. Aging is fastest near the beginning, and the absolute capacitance value stabilizes over time.
The rate of aging of Class 2 ceramic capacitors depends mainly on its materials. Generally, the higher the temperature dependence of the ceramic, the higher the aging percentage. The typical aging of X7R ceramic capacitors is about 2.5&nbs;% per decade. The aging rate of Z5U ceramic capacitors is significantly higher and can be up to 7% per decade.
The aging process of Class 2 ceramic capacitors may be reversed by heating the component above the Curie point.
Class 1 ceramic capacitors and film capacitors do not have ferroelectric-related aging. Environmental influences such as higher temperature, high humidity and mechanical stress can, over a longer period, lead to a small irreversible change in the capacitance value sometimes called aging, too.
The change of capacitance for P 100 and N 470 Class 1 ceramic capacitors is lower than 1%, for capacitors with N 750 to N 1500 ceramics it is ≤ 2%. Film capacitors may lose capacitance due to self-healing processes or gain it due to humidity influences. Typical changes over 2 years at 40 °C are, for example, ±3 % for PE film capacitors and ±1 % PP film capacitors.
Other articles related to "aging":
... He was supposed to be aging much slower than other humans due to an aging-suppression factor given to him at Weapon X ... As the aging-suppression had somehow failed, he ultimately died of old age in Jubilee's arms ...
... of virtual gerontogenes regarding the nature of genes involved in aging that real gerontogenes do not exist ... Additionally, in the area of aging modulation, Suresh Rattan is credited with the sole inventorship for discovering the anti-aging effects of kinetin and zeatin in human skin cells and these compounds are ... His areas of expertise include aging, anti-aging and healthy aging of human cells, specially fibroblasts, keratinocytes, osteoblasts, and bone marrow stem cells ...
... The continuity theory of normal aging states that older adults will usually maintain the same activities, behaviors, personalities, and relationships as they did in their earlier years ... theory uses a life course perspective to define normal aging ...
... involved may diminish a wine's aroma, flavor, texture, color or aging potential ... deliberately leave more tartrates and phenolics in wines designed for long aging in bottle so that they are able to develop the aromatic compounds that constitute bouquet ... and Port, may expect to see tartrates and sediment after aging in bottle ...
... Aging or ageing may also refer to Aging (task scheduling), an operating system process Ostwald ripening, precipitate or deposit aging in chemistry Polymer ...
Famous quotes containing the word aging:
“You are truly the generation in the middle! You have at once aging parents as well as maturing children to cope with, and you are not granted the deference accorded age, or the indulgence given the young.”
—Helene S. Arnstein (20th century)
“The politics of the exile are fever,
theater of the aging convalescent.
You wait in the wings and rehearse.
You wait and wait.”
—Marge Piercy (b. 1936)
“Bourbons the only drink. You can take all that champagne stuff and pour it down the English Channel. Well, why wait 80 years before you can drink the stuff? Great vineyards, huge barrels aging forever, poor little old monks running around testing it, just so some woman in Tulsa, Oklahoma can say it tickles her nose.”
—John Michael Hayes (b.1919)