What is the main role of the chip capacitor electrolyte

SMT capacitor positive aluminum foil, the medium is close to the positive plate of alumina, negative plate does not have to be a metal, as long as it is a conductor, so the aluminum electrolytic capacitor negative electrolyte.

Theoretically, or non-commercial aluminum electrolytic capacitors do not require an additional negative plate, just insert the negative lead into the electrolyte. But as the actual product, add a layer of aluminum foil as the electrolyte guide, aspect link, because it is also similar to the positive plate aluminum foil, so it is often misunderstood as a negative plate.

So the actual gap between the false negative plate and the positive plate, the capacity of the electrolytic capacitor may be smaller than the mica capacitor of the same volume, because the gap with the positive plate is too large. Open an electrolytic capacitor over the master will know that in fact electrolytic capacitor it is not a few layers that a lot of people will question, so where is the large capacity? In fact, the aluminum electrolytic capacitor is the layer of alumina, very thin, and the positive plate aluminum foil surface shape rough, bumpy, increased the effective area. The cathode is through the electrolyte impregnated paper and alumina medium close contact. Although alumina is thin and resistant to high voltage, it is directional and can only be insulated when connected in a positive or negative way, which is why electrolytic capacitors have polarity.

The electrolyte is the most traditional electrolyte, which is obtained by heating the organic solvent GAMMAD butyllactone with weak acid capacitor. In the common sense, the cathode of aluminum electrolytic capacitor is this electrolyte.

When the chip capacitor using electrolyte cathode has many advantages: the first is that the liquid and the medium of the contact area is larger, which is helpful to improve the capacitance; The second is the use of electrolyte high temperature resistance ability is good, can use SMT process, and pressure resistance is also relatively strong; In addition, the electrolytic capacitor using electrolyte as the cathode can heal itself when the dielectric is broken down, as long as the breakdown current is not sustained (metal oxides can be generated automatically).

The electrolyte capacitor also has its shortcomings: firstly, it is easy to volatilize and leak in the high temperature environment, which has a great impact on the life and stability. Under high temperature and high pressure, the electrolyte may vaporize instantaneously, and the increase of the volume may cause the explosion. Secondly, the ionic conductivity method adopted by the electrolyte has a very low conductivity, only 0.01S/CM (conductivity, the inverse of ohm), which results in the ESR value of the capacitor (equivalent series resistance). Impedance is extremely high.

A capacitor with aluminum at the anode and electrolyte at the cathode, formally known as an aluminum electrolytic capacitor, is called a "liquid" capacitor because of the presence of a liquid.