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In this document, we explain the basic knowledge of capacitor characteristics, incorporating examples and data. In "Capacitance (Main Text)," we discuss dielectrics, the rules for units and symbols of capacitance, and the range of capacitance covered by capacitors. In "About the Capacitance of Aluminum Electrolytic Capacitors," we introduce the structure of the elements and the changes in capacitance due to temperature, using diagrams and graphs. Please feel free to download and take a look. [Contents (Partial)] ■ Capacitance (Main Text) - What is capacitor capacitance? - About dielectrics - Rules for units and symbols of capacitance - Range of capacitance covered by capacitors - Characteristics and properties of capacitance (things to be careful about) *For more details, please refer to the PDF document or feel free to contact us.

In this document, we explain the concept of impedance as part of the fundamental knowledge of capacitor characteristics. We cover topics such as "What is impedance?", "The impedance of actual capacitors," and "Important elements that constitute impedance (ESR, ESL)." We also explain the characteristics of the ESR of aluminum electrolytic capacitors that use an electrolyte. Please feel free to download and take a look. 【Contents】 ■ What is impedance? ■ The impedance of actual capacitors ■ Important elements that constitute impedance (ESR, ESL) ■ ESR and ESL of aluminum electrolytic capacitors ■ Summary *For more details, please refer to the PDF document or feel free to contact us.

Here is a case where a sound like "zi" or "pi" was heard from a film capacitor when the power was turned on. Film capacitors have a structure that consists of extremely thin plastic film rolled up. While the electrodes at both ends of the element are fixed, the body part is not fixed, making it prone to vibration. When voltage is applied to the capacitor, the Coulomb force acting between the electrodes can cause the dielectric plastic film to vibrate mechanically, resulting in a humming sound. In particular, if there is distortion in the power supply voltage or if the waveform contains harmonic components, the sound level can be high. [Countermeasures] ■ Continuous vibration sound - It is not a malfunction; it does not affect electrical characteristics or reliability. - Capacitors with long cylindrical or flat-shaped elements tend to produce louder sounds. ■ If the sound level exceeds the acceptable range or if there are sporadic popping sounds - Please use a "sound-dampening product" with a short cylindrical shape. *For more details, please refer to the PDF document or feel free to contact us.

The lead wire film capacitor mounted on the substrate was coated with resin. The connection between the capacitor element and the lead wire sparked, causing the capacitor to ignite. The cause was that the coated resin repeatedly expanded and contracted, applying stress to the capacitor. As a result, the connection between the capacitor element and the lead wire experienced stress and delaminated, leading to a spark when voltage was applied, which caused the capacitor to ignite. [Countermeasures] ■ When applying an overcoat, select resin considering the thermal expansion coefficient of the substrate. * For more details, please refer to the PDF document or feel free to contact us.

When the foil electrode type film capacitor was changed to a vapor-deposited electrode type film capacitor with the same rating, the capacitor failed open. Even with the same rating, the vapor-deposited electrode type is set to have a lower pulse current tolerance than the foil electrode type. This is because the vapor-deposited electrode has a higher resistance and generates more heat than the foil electrode. When a steep pulse current or high-frequency current is applied to the vapor-deposited electrode type, the capacitor heats up, causing the dielectric film to thermally shrink, which damages the junction between the vapor-deposited electrode and the collector electrode (metal spraying), leading to an unstable connection. Ultimately, the connection between the two becomes disconnected and fails open, but when high voltage is applied, sparks may occur, potentially causing a fire. [Countermeasures] ■ Ensure that the actual applied current remains below the allowable value. *For more details, please refer to the PDF document or feel free to contact us.

The film capacitor in the power circuit shorted and caught fire. In this case, a film capacitor with a vapor-deposited electrode designed for DC was used in an AC circuit. The effective value of the AC voltage and the DC rated voltage of the capacitor were almost the same. As a result, a voltage exceeding the rated voltage continued to be applied to the capacitor, leading to a short circuit and fire. [Countermeasures] - Change to a film capacitor suitable for AC - Set the rated voltage of the capacitor with an adequate margin, considering AC frequency, voltage waveform, voltage fluctuations, and operating temperature - If the DC voltage contains an AC component, it is necessary to choose a capacitor with a DC rated voltage higher than the peak voltage *For more details, please refer to the PDF document or feel free to contact us.

We would like to introduce a case where a series-connected aluminum electrolytic capacitor short-circuited. When a capacitor with a high leakage current is included in a capacitor series, the voltage balance can be disrupted, causing the voltage to drift above the rated voltage, which may lead to the capacitor short-circuiting. For this reason, it is recommended to connect resistors (voltage divider resistors) in parallel with each individual capacitor when connecting capacitors in series. However, in this case, the leakage resistances of the individual capacitors varied significantly, causing the voltage divider resistors to not function properly. 【Countermeasures】 - To achieve a uniform voltage distribution across the series-connected individual capacitors, increase the rated voltage of the capacitors to reduce the disparity in leakage currents, and review the values of the voltage divider resistors. - Use capacitors from the same manufacturing lot to align the behavior of leakage currents against temperature changes and voltage fluctuations. - This can help stabilize the voltage division. *For more details, please refer to the PDF document or feel free to contact us.

We would like to introduce a case where a horizontally mounted screw terminal aluminum electrolytic capacitor failed and the sealing part burst. The failed screw terminal aluminum electrolytic capacitor was mounted horizontally with the pressure relief valve positioned at the "6 o'clock" direction. When a capacitor deteriorates or fails, the temperature of the capacitor element rises rapidly, causing gas to be generated inside. This capacitor uses a filler material to secure the element, and as the element temperature increases, this filler material softens and flows, blocking the pressure relief valve. As a result, the smooth operation of the pressure relief valve was hindered, leading to a crack in the sealing part. [Countermeasures] - Change the mounting method so that the pressure relief valve of the aluminum electrolytic capacitor is positioned at the "12 o'clock" direction. - Adopt a structure that secures the element with ribs instead of using filler material. *For more details, please refer to the PDF document or feel free to contact us.

During the replacement work of an aluminum electrolytic capacitor, when the terminals of the capacitor were connected with metal, a spark occurred, surprising the operator. When the capacitor is discharged, the charge stored in the electrodes disappears instantly, and the voltage between the terminals appears to be zero, but the dipole polarization of the dielectric is maintained. If the capacitor is opened with a short discharge time, the voltage is induced again at the electrodes due to the dipole polarization remaining in the dielectric. In other words, the charge stored in the dielectric seeps out and generates a re-induced voltage at the terminals. A spark occurred because the terminals were short-circuited with a conductor in this state. [Countermeasures] ■ Before handling the capacitor, connect a resistor of about 100Ω to 1kΩ between the terminals of the capacitor to discharge the accumulated charge. *For more details, please refer to the PDF document or feel free to contact us.

We would like to introduce a case where an aluminum electrolytic capacitor, which had been stored for a long time as a spare part, exhibited increased leakage current. Aluminum electrolytic capacitors have the property that their leakage current increases when stored for a long time without a DC bias and under no load, and this property becomes more pronounced at higher storage temperatures. This is believed to be due to the degradation of the dielectric oxide film at high temperatures, which reduces its insulation properties. When voltage is applied in this state, the leakage current increases. 【Countermeasures】 ■ Store capacitors at temperatures between +5°C and +35°C, with relative humidity below 75%. ■ Unless otherwise specified, our aluminum electrolytic capacitors can be stored without voltage under the above conditions for up to 3 years. ■ If within the storage period, capacitors can be used at rated voltage immediately after being taken out from storage. ■ For capacitors that will be mounted on a circuit board by soldering, to prevent issues during soldering, they should be mounted within 2 years. *For more details, please refer to the PDF document or feel free to contact us.

We will introduce a case where a malfunction occurred during a low-temperature operation test of a DCDC converter, resulting in a decrease in output voltage. An aluminum electrolytic capacitor using electrolyte was used in the output section of the DCDC converter. Generally, at low temperatures below -20°C, the electrical conductivity of the electrolyte decreases and its viscosity increases, leading to a reduction in capacitance by several tens of percent, worsening frequency response, and increasing equivalent series resistance. As a result, it was determined that the transient response performance of the output voltage deteriorated, preventing the specified voltage from being achieved. [Countermeasures] - Confirm the capacitance, ESR, impedance, and frequency characteristics of the capacitor at low temperatures, and select an appropriate capacitor. *For more details, please refer to the PDF document or feel free to contact us.

We would like to introduce a case where electrolyte leaked during use, causing a short circuit in the circuit board and resulting in capacitor failure. The electrolyte in aluminum electrolytic capacitors evaporates during operation, releasing gas into the atmosphere through the sealing rubber gasket. Additionally, aluminum electrolytic capacitors are equipped with pressure relief valves. Therefore, if the capacitor is covered with resin or similar materials, it can hinder the release of gas and the operation of the pressure relief valve. In this case, the coating material blocked the pressure relief valve, impairing its function and causing the sealing part of the capacitor to break, leading to electrolyte leakage. As a result, the circuit board wiring short-circuited, and the capacitor failed. **Countermeasures** - Do not cover the entire circumference of the capacitor with coating agents or resin. - Most of our aluminum electrolytic capacitors can withstand vibration tests with acceleration of up to 10G. *For more details, please refer to the PDF document or feel free to contact us.*

We were using five aluminum electrolytic capacitors of the same rating and lot in parallel to eliminate ripple current, but I would like to introduce a case where one of these capacitors failed and the pressure relief valve was activated. Due to the constraints of the component layout on the circuit board, the failed capacitor was installed at a position away from the other capacitors. In that position, there were heat-generating components adjacent to it, and due to the radiant heat from these components, this capacitor was exposed to higher temperatures than the others. As a result, it experienced wear failure in a relatively short period, which caused the pressure relief valve to activate. [Countermeasures] - Review the mounting arrangement of the capacitors - Change the cooling method to mitigate the effects of radiant heat - It is recommended to use long-life capacitors that can handle high ripple currents *For more details, please refer to the PDF document or feel free to contact us.

In this case, snap-in aluminum electrolytic capacitors were used in the power supply equipment, and to make the equipment thinner, the heat sink was closely positioned against the top of the capacitor. During a test for abnormal conditions in the equipment, an intentional overvoltage was applied to the capacitor, which caused the pressure valve located on the top of the capacitor to fail to operate and resulted in overheating. Subsequently, vapor from the electrolyte burst out from the grounding surface of the capacitor. The cause was that the capacitor shorted due to the overvoltage, leading to current flow and overheating. The heat vaporized the electrolyte, causing pressure inside the capacitor to rise, and since the pressure valve did not operate, gas from the electrolyte burst out from the sealing part of the capacitor on the grounding surface, shorting the wiring pattern on the substrate and causing a spark that resulted in smoke. [Countermeasures] - Review the requirements for the pressure valve to operate and the regulations for ensuring safety, and secure the necessary space. - If sufficient space cannot be secured, a type with a pressure valve on the side of the capacitor is recommended. *For more details, please refer to the PDF document or feel free to contact us.

We will introduce a case where the capacity of aluminum electrolytic capacitors decreased in a circuit where the charging and discharging of capacitors, such as welding machines and strobe flashes, is frequently repeated. When charging and discharging aluminum electrolytic capacitors repeatedly, the following reactions continuously occur on the surface of the cathode foil. [During Charging] Gas generation due to the electrolysis of the electrolyte [During Discharging] The charge on the anode foil moves to the cathode foil, oxidizing the cathode surface As a result, internal pressure rises, leading to open failures when the pressure relief valve operates, or failures due to the decrease in capacity of the cathode foil, which reduces the capacitance of the capacitor. This phenomenon can occur not only during charging and discharging but also when a large voltage fluctuation is applied to the capacitor. [Countermeasures] ■ Use capacitors with specifications suitable for the charging and discharging circuit in circuits where frequent charging and discharging occurs. *For more details, please refer to the PDF document or feel free to contact us.

We would like to introduce a case where an aluminum electrolytic capacitor used in the DC link of an inverter circuit overheated, causing the pressure relief valve to activate and the electrolyte to spray out from the capacitor. The cause was that a ripple current exceeding the allowable value flowed into the capacitor, causing it to overheat beyond its design specifications. Due to the overheating, the insulation deteriorated, leading to a short circuit, and the gas generated from the electrolyte increased the pressure inside the capacitor. The pressure relief valve activated, resulting in the electrolyte spraying out in aerosol form. **Countermeasures** - Confirm that the magnitude and waveform of the expected ripple current during the design phase match the specifications. - Select capacitors considering the allowable ripple current, temperature, and frequency corrections. *For more details, please refer to the PDF document or feel free to contact us.*

This catalog is a comprehensive catalog featuring capacitors handled by AIC Tech Co., Ltd. We offer lead-free products that do not contain lead in the product terminals, as well as products that do not include polyvinyl chloride in the exterior materials, all of which comply with the European RoHS Directive (2011/65/EU and 2015/863/EU, etc.) as standard products in our lineup. [Contents] ■ Aluminum Electrolytic Capacitors - Screw terminal aluminum electrolytic capacitors - PCB mount aluminum electrolytic capacitors - Lead terminal aluminum electrolytic capacitors ■ Plastic Film Capacitors - Plastic film capacitors for power electronics, etc. *For more details, please download the PDF or feel free to contact us.

We would like to introduce a case where the pressure relief valve of an aluminum electrolytic capacitor used in the power supply section operated and emitted smoke. The cause was that an overvoltage was applied to the aluminum electrolytic capacitor due to fluctuations in the input voltage, resulting in a short circuit of the capacitor. Current flowed through the capacitor, causing it to heat up and generate gas from the electrolyte. The pressure inside the capacitor increased due to the generated gas, causing the pressure relief valve to operate, and the electrolyte was ejected in aerosol form. 【Countermeasures】 <Check the voltage applied to the capacitor> ■ Is there any voltage fluctuation? ■ Does the peak value (V top) of the fluctuating voltage exceed the rated voltage? ■ Does the negative peak value (V bottom) of the fluctuating voltage exceed zero and become reverse voltage? ■ Is the range of fluctuation of the peak value excessively large? *For more details, please refer to the PDF document or feel free to contact us.

This document introduces the basic knowledge of electric double-layer capacitors, which have a simple structure and energy storage principle, and are safer and cleaner compared to other devices that utilize chemical reactions. It explains the principles and features, and discusses sustainable applications and future potential. The overview of electric double-layer capacitors (EDLC) and the principles of their structure and energy storage are detailed with diagrams and images. [Content Overview (Partial)] ■ Overview of Electric Double-Layer Capacitors (EDLC) - EDLC is an old yet new energy device. - EDLC is a device that bridges the gap between capacitors and batteries. ■ Why EDLC Stores Electricity (Structure and Energy Storage Principle) - Basic structure of EDLC and electric double layer. - Principle of energy storage (why EDLC can store a large amount of electrical energy). - EDLC is a physical battery. *For more details, please refer to the PDF document or feel free to contact us.

AICTech's capacitors apply strict quality control and safety standards in product design and manufacturing. However, it is difficult to achieve zero failures in capacitors with current technology standards. The handbook explains the failure modes, phenomena, causes, and countermeasures of capacitors, illustrated with case studies. [Contents (partial)] ■ How capacitors fail - Explanation of failure modes: open failure, short failure, etc. ■ Phenomena and case studies of failures, factors, and countermeasures (15 selected case studies included!) - Smoke coming from the capacitor - Loss of capacitance - Short-circuiting, etc. For confirmation points regarding countermeasures for these failures, detailed information is provided in the materials. *If you would like a copy of the handbook, please request the materials or view the PDF data available for download.

AICTech's capacitors apply strict quality control and safety standards in product design and manufacturing. However, it is difficult to achieve zero failures in capacitors with current technological standards. The handbook explains the phenomena and causes of capacitor failures, along with examples of countermeasures, illustrated with diagrams. [Contents (partial)] ■ Symptoms to look for in capacitors ■ How capacitors fail (failure modes and factors) ■ Phenomena and examples of failures, factors and countermeasures (15 selected examples included!) ■ Appendix: Basic knowledge of capacitors *If you would like a copy of the handbook, please request the materials or view the PDF data from the download.

AICTech's capacitors apply strict quality control and safety standards in the design and manufacturing of their products. However, with current technology levels, it is difficult to achieve zero failures in capacitors. When a failure occurs, the capacitor loses its basic functions of storing charge in direct current and eliminating noise and ripple current. In the worst case, there is a risk of ignition leading to a fire. If you notice conditions such as "cracks in the case" or "smoke coming out," it indicates a failure, and you must immediately disconnect the power and take appropriate action. The related catalog explains the phenomena and causes of failures, as well as examples of countermeasures, to help you use capacitors properly. Please take a moment to read it. *For more details, please refer to the PDF document or feel free to contact us.*

When a capacitor fails open, the circuit becomes completely disconnected. For example, using a large-capacity capacitor in the power supply smoothing circuit can flatten a voltage waveform that resembles a large wave into a stable DC voltage. However, if the capacitor opens, high voltage may be applied to the circuit, potentially causing semiconductor failure. The main causes of open failure are disconnection or a significant increase in resistance. These often occur at the connection points between the capacitor's external terminals and the wiring. Since the external terminals, internal wiring, and structure vary depending on the type of capacitor, there are various types of open failures. In addition to usage of the capacitor, factors such as vibrations or shocks during transport, and the arrangement of equipment on the circuit board can also contribute to open failures. Our related catalog provides a wealth of information on various failure phenomena and cases, as well as causes and countermeasures. Please feel free to download and take a look. *For more details, please refer to the PDF materials or feel free to contact us.*

When a capacitor experiences a short circuit failure, it can no longer easily accumulate charge as current flows through it. For example, if a capacitor connected between the input side and ground to eliminate ripple current or noise shorts, a large current will flow from the input to ground. Causes of short circuit failures include applying voltage beyond the rated value, conducting ripple current, and usage under high temperature or high humidity. Additionally, for polarized capacitors, applying pure AC voltage or reverse voltage can also lead to shorts. Furthermore, because the dielectric of a capacitor is very thin, excessive mechanical stress can damage the dielectric and cause a short. It is important not only to consider electrical factors but also to ensure that the capacitor is not subjected to shocks or vibrations. Our related catalog provides a wealth of information on various failure phenomena and case studies, as well as factors and countermeasures. Please feel free to download and take a look. *For more details, please refer to the PDF materials or feel free to contact us.*

Aluminum electrolytic capacitors are essential electronic components for power circuits and electronic circuits due to their small size and large capacity. Most aluminum electrolytic capacitors are polarized, so they are typically used in DC circuits. Their operating principle utilizes chemical reactions, and they are also known as chemical capacitors. As a result, the performance of aluminum electrolytic capacitors is greatly affected by environmental factors such as temperature and atmosphere, and failures can occur due to rapid chemical reactions. In the related catalog, we provide detailed explanations of failure cases of aluminum electrolytic capacitors and film capacitors, along with their causes, root causes, and countermeasures. Please take a look. *For more details, please refer to the PDF materials or feel free to contact us.*

Aluminum electrolytic capacitors are polarized capacitors with a limited lifespan that apply electrochemical operating principles, and they are also known as chemical capacitors. These capacitors have high volumetric efficiency (capacitance per unit volume), can achieve large capacitance values in the thousands of microfarads, can withstand large ripple currents, and have high reliability, making them suitable for a wide range of applications in DC circuits. On the other hand, it is necessary to consider their relatively high leakage current compared to other capacitors, a wide capacitance tolerance range of ±20%, high equivalent series resistance, and their finite lifespan when using them. Related catalogs provide detailed information on the features and structure of aluminum electrolytic capacitors and film capacitors. Please feel free to download and take a look. *For more details, please refer to the PDF materials or feel free to contact us.*

A capacitor is one of the fundamental and important components in electronic circuits. There is no clear distinction between a capacitor and a condenser; both can physically store electric charge. In English-speaking countries, it is called a capacitor (from "electric capacity = capacity"), but in Japan, it is said to have been referred to as "condenser" (＝condenser) due to its function of compressing (＝condense) electricity. For more details, please refer to the PDF download below. *For more information, please refer to the PDF document or feel free to contact us.

I will introduce the mechanism and function of a capacitor. The circuit symbol representing a capacitor consists of two parallel lines. This indicates that the capacitor is made up of two parallel conductive plates. The larger the surface area of the capacitor's electrode plates and the closer the distance between the two plates, the greater the capacity to store electricity. Additionally, the electrode plates are electrically separated by an insulating material, which gives the capacitor the ability to block direct current while storing electricity (capacitance). These materials are generally referred to as dielectrics. 【Functions of a Capacitor】 ■ Stores charge (electricity) ■ Does not allow direct current to pass, but allows alternating current to pass *For more details, please refer to the PDF document or feel free to contact us.