Home > Blog > Industry News > Why high temperature & humidity are not friendly for capacitors? Capacitors, especially common electrolytic capacitors, are highly sensitive for high temperatures and humidity due to their inherent physical and chemical structures.
High temperature is considered as the most fatal factor for capacitors, it raise the risks in several ways:
Mechanism: The electrolyte or electrolyte fluid which stored in the capacitor, they could evaporate slowly or chemically decomposes with high temperatures. Over time, the electrolyte decreases, leading to a reduction in the capacitor's effective capacitance and increase the equivalent series resistance (ESR).
Consequences: Deteriorate the filtering function, increase power supply ripple, and in some severe cases, circuit malfunction. Increased ESR leads to increased capacitor heating, creating a vicious cycle that ultimately causes complete failure.
Mechanism: The lifespan of capacitor is exponentially related to temperature. A regulation is, everytime the temperature increase 10°C in working temperature, the capacitor's lifespan lost for almost half.
For example: A capacitor with a nominal lifespan as 2000 hours (@105℃) may only have an expected lifespan of about 1000 hours if working at 115℃.
Mechanism: The endurance capability of voltage for the insulating dielectric (oxide layer) between the capacitor plates would decrease significantly when increasing temperature.
Consequence: Under high voltage or voltage fluctuations, dielectric breakdown is more likely to occur, causing the capacitor to short-circuit or even explode.
Mechanism: High temperatures reduce the elasticity of the capacitor seal (rubber or rubber-like) and accelerate aging.
Consequence: Decrease the sealing performance, accelerate electrolyte evaporation and external moisture intrusion.
The threats from humid (high humidity) environments to capacitors are: electrochemical corrosion and degradation of insulation performance.
Mechanism: In humid environments, the metal leads of capacitors (usually copper or tin-plated iron) react with humidity and airborne contaminants (such as carbon dioxide and sulfides) to form an electrolyte, resulting in electrochemical corrosion.
Consequences: Lead corrosion will lead to poor soldering, open circuits, furthermore to failure.
Mechanism: humidity and contaminants would form tiny conductive paths on the capacitor's surface, significantly reducing surface insulation resistance. For multilayer ceramic capacitors (MLCCs), humidity may even penetrate into the ceramic dielectric.
Consequences: A sharp increase in current leakage not only increases power consumption but may also cause the capacitor to overheat and malfunction.
Mechanism: This is the most dangerous humidity failure. After absorbing humidity, during soldering (mostly, reflow soldering), the internal humidity in MLCC capacitor will be heated rapidly and vaporize, generating an enormous pressure from inside and causes cracks of the ceramics or at the solder joints.
Consequences: Cracks may cause a short circuit in the capacitor immediately, or they may become a potential defect, leading to complete failure, such as from vibration or thermal stress after a period.
1. High temperatures shorten the lifespan of capacitor, by accelerating internal chemical reactions (electrolyte drying) and material aging.
2. Humidity hurts capacitors directly by increase electrochemical corrosion and reducing insulation performance.
In some certain environments, high temperature and high humidity are often coexist at same time, and their combined effect can accelerate capacitor failure.
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If you need PCB and PCBA manufacturing services, please contact Benlida for consultation, Benlida is dedicated to provide excellent service!
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