从事电子元器件行业的人员经常会听到电解电容失效的问题，那么如何避免电解电容失效的问题呢？这就需要我们清楚的知道电解电容失效的原因以及在电路设计过程中注意的问题。
People engaged in electronic components industry often hear the problem of electrolytic capacitor failure, so how to avoid the problem of electrolytic capacitor failure? This requires us to know clearly the cause of electrolytic capacitor failure and the problems in the circuit design process.
1.铝电解电容为什么会失效呢?
Why does aluminum electrolytic capacitor fail?
2.铝电解电容失效与哪些因素有关?
What factors are related to the failure of aluminum electrolytic capacitor?
3.电解电容寿命如何计算?
How to calculate the life of electrolytic capacitor?
让我们依次来解答以上的问题。
Let's answer the above questions in turn.
1.铝电解电容为何失效?
Why aluminum electrolytic capacitors fail?
这个问题还得提下铝电解电容的构造。
The construction of aluminum electrolytic capacitors should also be mentioned.
通用型铝电解电容器的基本结构是箔式卷绕型的结构，阳极为铝金属箔，介质是用电化学方法在阳极金属箔表面上形成的阀金属氧化膜Al2O3，阴极则为多孔性电解纸所吸附的工作电解质。
The basic structure of general aluminum electrolytic capacitor is foil winding structure. The anode is aluminum foil, the medium is valve metal oxide film formed on the surface of anode metal foil by electrochemical method, and the cathode is working electrolyte adsorbed by porous electrolytic paper.
通俗理解，电容都是由两个导电板并排放到一起就构成了。正极是铝(阳极箔)，中间介质是不导电的氧化铝(阳极氧化膜)，负极就是电解液了。
Generally understood, the capacitor is composed of two conductive plates and discharged together. The positive electrode is aluminum (anode foil), the intermediate medium is non-conductive alumina (anodic oxide film), and the negative electrode is the electrolyte.
电解电容失效，主要原因就出在了这个电解液上了。这个电解液自己会分解产生气体，也会与氧化膜发生化学反应产生气体。当然，正常使用情况下，这个速率是非常慢的，不然岂不是没法用了。
Electrolytic capacitor failure, the main reason for this electrolyte. The electrolyte itself will decompose to produce gas, and will react with the oxide film to produce gas. Of course, under normal use, this speed is very slow, otherwise it can't be used.
所以，电解寿命的长短，主要决定于这个电解液，啥时候电解液没了，电容也就失效了。
Therefore, the life of electrolysis is mainly determined by the electrolyte. When the electrolyte is gone, the capacitor will fail.
2.铝电解电容失效影响因素
Influencing factors of aluminum electrolytic capacitor failure
铝电解电容失效速度与电解液的挥发速度有关，而挥发的速度主要取决于温度。电解电容内部的温度，取决与环境温度和纹波电流。
The failure rate of aluminum electrolytic capacitor is related to the evaporation rate of electrolyte, which mainly depends on the temperature. The internal temperature of electrolytic capacitor depends on the ambient temperature and ripple current.
如果是用在电源纹波比较小的场合，那么电解电容的温度就主要由环境温度决定了。
If it is used in the case of small ripple of power supply, then the temperature of electrolytic capacitor is mainly determined by the ambient temperature.
如果是用在在纹波电流比较大场合，电解电容的ESR是不能忽略的，比如用在开关电源里面，因为ESR的存在，电解电容会主动发热。
If it is used in the field with large ripple current, the ESR of electrolytic capacitor can not be ignored, such as in switching power supply, because of the existence of ESR, the electrolytic capacitor will actively heat up.
其实如果翻开电容规格书，我们也可以看到电解电容有个参数叫做最大纹波电流。
In fact, if we open the capacitance specification, we can see that electrolytic capacitor has a parameter called maximum ripple current.
以某厂的电解电容为例
Taking the electrolytic capacitor of a factory as an example
主要注意的是，这个纹波电流为有效值Irms。
It is important to note that the ripple current is RMS.
3.铝电解电容寿命计算
Life calculation of aluminum electrolytic capacitor
温度升高， 化学反应速率( 寿命消耗) 增大， 一般来说， 当所处环境温度每上升10℃ ，化学反应速率(K 值) 将增大 2-10 倍，即电容工作温度每升高 10℃ ，电容寿命减小一倍，电容工作温度每下降 10℃ ，其寿命增加一倍。
Generally speaking, when the ambient temperature increases by 10 ℃, the chemical reaction rate (k value) will increase by 2-10 times, that is, every 10 ℃ increase in the working temperature of the capacitor, the life of the capacitor will be doubled, and the life of the capacitor will be doubled when the working temperature of the capacitor decreases by 10 ℃.
Lo为电解电容工作最高温度对应的寿命，一般来说电解电容规格书都会有相应的参数。
Lo is the service life corresponding to the highest working temperature of electrolytic capacitor. Generally speaking, the specifications of electrolytic capacitor will have corresponding parameters.
需要注意的是，各个厂家的寿命计算公式不尽相同，不过也都是相近的。在设计电路时，通过公式计算出的寿命可以做一个大致的参考。
It should be noted that the life calculation formulas of different manufacturers are not the same, but they are all similar. In the design of the circuit, the life calculated by the formula can be used as a general reference.
由此我们可以得出以下结论：很多电解电容在最高温度工作时，寿命只有2000小时(0.2年)，所以必须考虑寿命问题。温度每升高10摄氏度，电解电容寿命下降一半。温度，纹波电流都是影响电解电容的重要因素。
Therefore, we can draw the following conclusion: when many electrolytic capacitors work at the highest temperature, the service life is only 2000 hours (0.2 years), so we must consider the life problem. When the temperature increases by 10 ℃, the life of electrolytic capacitor decreases by half. Temperature and ripple current are important factors affecting electrolytic capacitor.