Electrolytic capacitor: an electrolytic material in which a charge is stored inside, divided into positive and negative polarities, similar to batteries, Metal substrate (aluminum or tantalum) that is strongly adhered to the oxide film and the negative electrode is connected to the electrolyte (solid and non-solid) through the metal electrode.
The non-polar (bipolar) electrolytic capacitor is constructed with a double oxide film structure, which is similar to two polar electrolytic capacitors which are connected by two negative electrodes. The two electrodes are connected by two metal electrode plates (both coated with oxide film). Electrolytes are in the middle of two groups of oxide films. Electrolytic capacitors with polarity are usually filtered, decoupled, signal coupled and time constant set in power supply circuit or intermediate frequency and low frequency circuit. Nonpolar electrolytic capacitors are usually used in audio frequency divider circuit, TV S correction circuit and starting circuit of single phase motor.
As the main board, power supply and other products basically use electrolytic capacitors, so this is the focus of our talk. We are familiar with aluminum capacitors, Tantalum capacitors are actually electrolytic capacitors. If capacitors are the most important and irreplaceable components in electronic components, then electrolytic capacitors occupy half of the capacitor industry. The annual output of electrolytic capacitors in China is 30 billion. The annual average growth rate is as high as 30%, accounting for more than 1/3 of the global electrolytic capacitance output.
Electrolytic capacitors feature one: the unit volume of capacitance is very large, than other types of capacitors tens to hundreds of times larger.
Electrolytic capacitor features two: the rated capacity can be very large, can be easily achieved tens of thousands of f or even a few f (but can not be compared with the double layer capacitance).
Electrolytic capacitors feature # 3: price has an overwhelming advantage over other types of capacitors, because the components of electrolytic capacitors are common industrial materials, such as aluminum, etc. The equipment used to manufacture electrolytic capacitors is also common industrial equipment. Can be mass production, relatively low cost.
The capacitance itself is upright to the PCB in either the plug-in or the mounting process. The fundamental difference is the capacitance installed in the SMT patch process. The advantages of having a black rubber base are mainly in production, and the degree of automation is high. The accuracy is also high and it is not as easily damaged in transit as the plug-in type. However, the installation of the SMT patch process requires wave soldering, and the capacitance may affect its performance after high temperature, especially when the cathode is made of electrolytes. After high temperature, the electrolyte may dry up. The installation cost of the plug-in process is low, so at the same cost, the performance of the capacitor itself can be Better. Because European and American factories have lower cost of machinery and more expensive labor, most of them tend to manufacture SMT patches. Domestic factories are cheaper, so manufacturers prefer plug-in installation.
In terms of performance, plug-in capacitance is less adaptable to frequency, but it is difficult to show the difference when frequency is less than 500MHz.