Comparison of Ultra-Small Electrolytic Capacitors and Tantalum Electrolytic Capacitors
Release time:
2022-06-15
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Ultra-small electrolytic capacitors have large volumes, high series resistance, high inductive reactance, and are highly sensitive to temperature. They are suitable for applications with relatively stable temperatures and low operating frequencies (not exceeding 25 kHz). They can be used for low-frequency filtering—when the frequency is high, parallel connection of electrolytic capacitors becomes less effective for filtering. Ultra-small electrolytic capacitors are polarized; during installation, it is essential to ensure that the polarity is correct, otherwise there is a risk of explosion.
Ultra-small electrolytic capacitor Comparison with tantalum electrolytic capacitors:
1. Ultra-small electrolytic capacitors have large volumes, high series resistance, high inductive reactance, and are highly sensitive to temperature. They are suitable for applications with relatively stable temperatures and low operating frequencies (not exceeding 25 kHz). They can be used for low-frequency filtering; however, when the frequency is high, parallel connection of electrolytic capacitors becomes less effective for filtering. Ultra-small electrolytic capacitors are polarized, so it’s crucial to ensure proper polarity during installation—otherwise, there is a risk of explosion.
2. Compared to ultra-small electrolytic capacitors, tantalum electrolytic capacitors have distinct advantages in terms of series resistance, inductance, and temperature stability. However, their operating voltage is relatively low.
Generally, the surge voltage for ultra-small electrolytic capacitors is taken as 1.3 times their rated voltage. This is the voltage guaranteed by the manufacturer to be tolerable for short periods. When a capacitor is subjected to surge voltage, the current can become very high—typically 10 to 15 times the normal operating current. If the duration of this surge is too long, the capacitor may rupture due to overheating. Therefore, when selecting aluminum capacitors, it’s advisable to choose a slightly higher rated voltage; the actual operating voltage should be between 70% and 80% of the nominal rated voltage.
Ultra-small electrolytic capacitor The distinction between tantalum electrolytic capacitors and other types is not determined by the appearance of the package. For instance, when we see small yellow or black rectangular components, we often assume they’re tantalum electrolytic capacitors—but in reality, their anodes could also be made of aluminum. Traditionally, it’s been believed that tantalum capacitors outperform aluminum capacitors because the dielectric material in tantalum capacitors is tantalum pentoxide, which is formed through anodic oxidation; this material has a higher dielectric constant ε than the aluminum oxide dielectric used in aluminum capacitors. Consequently, for the same capacitance, tantalum capacitors can be manufactured in smaller volumes compared to aluminum capacitors. (The capacitance of an electrolytic capacitor depends on both the dielectric constant of the medium and the volume of the capacitor. At a given capacitance, the higher the dielectric constant, the smaller the volume that can be achieved; conversely, the lower the dielectric constant, the larger the volume required.)
Due to their small size and relatively stable performance, tantalum capacitors are generally considered superior to aluminum capacitors. However, this method of judging capacitor performance based solely on the anode has become outdated. Today, it is widely recognized that the key factor determining the performance of electrolytic capacitors is not the anode, but rather the electrolyte—the cathode. Since different cathodes can be paired with different anodes to form various types of electrolytic capacitors, their performances can differ significantly. Moreover, even when using the same anode, capacitors made with different electrolytes may exhibit vastly different performance characteristics. In short, the influence of the anode on capacitor performance is far less significant than that of the cathode.
Experience using electrolytic capacitors:
1. In a filtering circuit, the voltage rating of an electrolytic capacitor should be 1.2 to 1.5 times the peak value of the noise, rather than the rated value specified for the filtering circuit itself.
2. There shall be no solder pads or vias directly beneath electrolytic capacitors.
3. Electrolytic capacitors must not come into direct contact with surrounding heat-generating components.
4. Ultra-small electrolytic capacitor Components have positive and negative terminals and must not be subjected to reverse voltage or AC voltage. Where reverse voltage may occur, non-polarized capacitors should be used.
5. Ultra-small electrolytic capacitors are not suitable for ground wires that require rapid charging and discharging; instead, capacitors with longer lifespans and specifically designed for such applications should be selected.
6. Overvoltage should not be used.
One: The sewing voltage, after the DC voltage is superimposed with the ripple voltage, is lower than the rated value.
When two or more electrolytic capacitors are connected in series, a balancing resistor should be considered to ensure that the voltage across each capacitor remains within its rated range.
7. When designing circuit boards, ensure that there are no wires above the capacitor’s explosion-proof valve, and maintain a clearance of at least 2 mm.
8. The electrolyte is primarily a chemical solvent, and the electrolytic paper is highly flammable. The electrolyte itself is conductive. When the electrolyte comes into contact with a PC board, it may corrode the circuit traces on the board, leading to smoking or even fire. Therefore, no circuit traces should be located beneath electrolytic capacitors.
9. When designing printed circuit boards, ensure that发热 components are not placed near ultra-small electrolytic capacitors or at the bottom of electrolytic capacitors.
Keywords:
Ultra-small electrolytic capacitor
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