Dielectric Materials and Components PDF

Dielectric Materials and Components Basic Principles of a Capacitor Charge Storage: Capacitors store energy as The dielectric behavior of a material is its ability to separated positive and negative charges on tw...

Dielectric Materials and Components Basic Principles of a Capacitor Charge Storage: Capacitors store energy as The dielectric behavior of a material is its ability to separated positive and negative charges on two plates. store energy and be polarized by an electric field. The Dielectric Material: An insulating layer enhances most important property of a dielectric is its electrical charge storage and prevents leakage. polarization, which occurs when a dielectric Capacitance: Measures the capacity to store charge, is placed in an electric field. When a dielectric is placed depending on plate size, spacing, and dielectric. Unit in in an electric field, its charges shift slightly, causing Farad (F) polarization. Positive charges move with the field, and Voltage-Charge Relationship: Stored charge is negative charges move opposite, creating an internal proportional to applied voltage (Q=CV). field that reduces the overall field in the material. Energy Storage: Energy is stored in the electric field Electric susceptibility measures how easily a dielectric as E =1/2(CV*2) can be polarized. Charging/Discharging: Capacitors charge with a voltage source and discharge to release energy. Classification of Dielectric Materials Physical State Classification of Capacitor Solid: Examples include ceramics, plastics, mica, and A. BASED ON STRUCTURE glass. Solid dielectrics are often used in capacitors, Fixed Capacitor transformers, and switches. Fixed capacitors have a set capacitance value that Liquid: Examples include transformer oil and silicone cannot be adjusted, maintaining constant charge and oil. Liquid dielectrics are used in high-voltage energy output. transformers. Variable Capacitor Gas: Examples include SF6, nitrogen, and dry air. Gas Variable capacitors allow capacitance adjustment to dielectrics are used for insulation in high-voltage provide varying power levels as needed in circuits. systems. Trimmer Capacitor Trimmer capacitors are used to calibrate or adjust the Polarity capacitance of circuits, Polar: These materials have a permanent dipole typically mounted on PCBs and not for general use. moment, meaning the positive and negative charges are separated. This creates an internal electric field that B. BASED ON POLARIZATION reduces the material's capacitance. Polarized Capacitor Non-polar: These materials have an even distribution Polarized capacitors have distinct positive and negative of positive and negative charges. This allows them to terminals and must be installed correctly in a circuit, store more electrical energy and have a higher typically used for higher capacitance but with potential capacitance. issues like leakage currents and short lifespan. Non-Polarized Capacitor Parameters of Dielectric Materials Non-polarized capacitors have no designated terminals, Conductivity offering versatility in AC circuits and high-frequency Measures a dielectric material's ability to allow a small applications without the limitations of polarized leakage current under an electric field. capacitors. Loss angle The angle between the voltage and current in a SELECTION CONSIDERATION OF CAPACITORS dielectric, representing the phase difference due to A. Capacitance energy dissipation. Ensure the value matches the circuit's requirements Power Factor for energy storage. The ratio of the real power (energy dissipated) to the B. Voltage Rating apparent power in a dielectric, indicating energy Choose a capacitor with a voltage rating higher than efficiency. the circuit's maximum operating voltage. Permittivity C. Dielectric Type Describes a material's ability to polarize in response to Select based on the application, e.g., ceramic for an electric field, affecting its energy storage capability. high-frequency, electrolytic for high capacitance. D. Temperature Range CAPACITORS Ensure the capacitor can operate within the a capacitor is a device that stores electrical energy by expected temperature range. accumulating electric charges on two closely spaced E. Size and Form Factor surfaces that are insulated from each other. Consider the physical space available in the circuit. F. Lifetime and Reliability  Consider the expected lifespan, especially for critical Repeated charging and discharging can reduce or long-term applications. capacitance over time, especially in electrolytic capacitors CAPACITOR PARAMETERS Capacitance DIELECTRIC MATERIAL PRODUCTS The amount of charge a capacitor can store, crucial MANUFACTURING for determining its energy storage capacity Voltage Rating MICA CAPACITORS The maximum voltage the capacitor can handle Dielectric Material Used: Mica before breakdown occurs Offers high stability ESR (Equivalent Series Resistance) low-loss A measure of the interna resistance that affects excellent reliability particularly in high-frequency and efficiency, particularly at high frequencies precision applications Tolerance commonly used in RF circuits and oscillators The acceptable variation from the specified wide performance range capacitance value, important for precision more expensive than ceramic capacitors applications Leakage Current BATTERIES A small current that flows through the capacitor even Dielectric Material Used: when it is not in operation, affecting its reliability Fiberglass Mica CAPACITOR CODES Polytetrafluoroethylene (PTFE) You can read the value from most capacitors. The only Polyethylene (PE) and more difficult to read capacitors are the very small ones Stores electrical energy chemically and releases it because there is not much space on them to put a value. through electrochemical reactions. These small capacitors have 3 numbers on them and has two electrodes and an electrolyte sometimes only two. Types: If there are only two numbers you will have to read the Lithium-Ion value as pf. For instance the number 33 printed on a Lead-Acid capacitor means its 33 pf. With 3 numbers this works Nickel Cadmium different. The first number represents the tens, the second number the ones and the third number is the MOSFETS multiply factor. Dielectric Material Used: Silicon Dioxide (SiO2) TOLERANCE Aluminum Oxide (A|203) Sometimes there is also a fourth indicator at the end of metal-oxide-semiconductor field-effect transistors the 3 number code. For instance 102K means a 1.000 a type of field-effect transistor (FET) that use an pf capacitor with a +/- 10 % tolerance. electric field to control current flow. four terminal contacts: gate (G), source Troubles of Capacitor (S), drain (D), and substrate body (B). Overvoltage/Overcurrent used to switch or amplify voltages in circuits Exceeding the rated limits can cause dielectric breakdown and internal arcing TRANSFORMERS Ripple Current Dielectric Material Used: High ripple currents generate excessive heat, Fiberglass leading to short-circuiting or insulation failure Mica Moisture Ingress Aramid Fiber Paper Moisture exposure can lead to leakage, corrosion, NOMEX and short circuits Mylar and More Temperature Extremes a device that steps up or steps down voltage. High temperatures can cause material degradation, a voltage control device that is used widely in the while low temperatures can reduce performance distribution and transmission of alternating current Mechanical Stress power Physical damage from shocks or vibrations can commonly used to increase or decrease the supply cause short circuits or open circuits voltage without a change in the frequency of AC Frequent Cycling between circuits SOLAR PANELS Dielectric Material Used: Silicon dioxide (Sio2) Silicon nitride (SINx) Aluminium oxide SIN:H are made of photovoltaic (PV) cells that release electrons when exposed to sunlight. transforms light made up of photon energy units into electricity for various applications. environmentally friendly used for residential, commercial, and industrial purposes, as well as in space. They can be mounted on rooftops or on solar farms.