Kemet recently came out with a new paper on Ceramic Capacitor Aging and I wanted to share some information on the key topics of Aging, Aging Rate and Deaging.
Capacitor aging is a change in capacitance at a constant rate over time. Aging is generally expressed as a percentage per decade hour. Matt R has a great post that explains the decade hour.
To help with aging calculations, Kemet has created a Ceramic Aging Calculator r1.xls (185 KB)
Capacitance testing and aging is a topic that causes many people to think that there is an issue with new unused capacitors. We also have a post on testing high capacitance MLCC’s. Many times we find that due to aging, the values people see in their test measurements is slightly off from the data sheet values.
The great news is that in most instances this can be reversed through Deaging. Most commonly, this is done through the manufacturing process. By going through the reflow solder process the capacitor’s temperature is brought above the curie point and thus is naturally reset back to the original value and the age date/time is reset to 0.
For those users who need this reset before starting the manufacturing process, Kemet also recommends a baking process.
“to place the capacitors in a 150ºC oven for a minimum
of 30 minutes. The time above the curie point is not critical and
once the capacitor reaches above the curie point, deaging occurs.
However, KEMET specifies 30 minutes at 150ºC to allow enough time
to exceed the curie point.”
For more information, see Kemet’s “Ceramic Capacitor Aging: What to Expect” paper below
TechTopic Ceramic Aging PDF.pdf (372.9 KB)