[Explanation of the Causes of Capacitor Failure] A case where characteristics deteriorated after long-term storage.
A Must-Read Guide for Circuit Designers: 15 Cases of Causes and Countermeasures for Capacitor Failures
Please store the capacitors at a temperature between +5°C and +35°C, with a relative humidity of 75% or lower!
We would like to introduce a case where an aluminum electrolytic capacitor, which had been stored for a long time as a spare part, exhibited increased leakage current. Aluminum electrolytic capacitors have the property that their leakage current increases when stored for a long time without a DC bias and under no load, and this property becomes more pronounced at higher storage temperatures. This is believed to be due to the degradation of the dielectric oxide film at high temperatures, which reduces its insulation properties. When voltage is applied in this state, the leakage current increases. 【Countermeasures】 ■ Store capacitors at temperatures between +5°C and +35°C, with relative humidity below 75%. ■ Unless otherwise specified, our aluminum electrolytic capacitors can be stored without voltage under the above conditions for up to 3 years. ■ If within the storage period, capacitors can be used at rated voltage immediately after being taken out from storage. ■ For capacitors that will be mounted on a circuit board by soldering, to prevent issues during soldering, they should be mounted within 2 years. *For more details, please refer to the PDF document or feel free to contact us.
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Please take note of the following: ■ If the capacitor has been stored at temperatures above 35°C or beyond the specified period, the leakage current may increase during the first charging after long-term storage or during short charging at high temperatures. ■ By properly applying voltage before use, it is possible to repair the deteriorated oxide film of the electrolyte and reduce the leakage current. *For more details, please refer to the PDF document or feel free to contact us.*
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If you see the following symptoms in a capacitor, it is faulty: ■ The case is swollen (bulging) ■ There are cracks in the case ■ There is a gap between the case and the sealing part ■ The pressure valve has activated (the pressure valve has opened) ■ The case has burst ■ It is hot or generating heat ■ Smoke is coming out ■ There is liquid leakage ■ There are unusual sounds ■ There is an unusual smell *For more details, please refer to the PDF document or feel free to contact us.
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AIC tech handles Aluminum electrolytic capacitors and Film capacitors for industrial market. Our capacitors have a history of more than 70 years and have their origins in technological development in Japan. AIC tech delivers high-value, precision capacitors tailored for power electronics—from renewable energy and industrial systems to transportation, ICT/IoT, healthcare, and infrastructure. Please feel free to contact us if you have any requests.