Mica capacitors use thin sheets of mica as the dielectric material between conductive plates. They are known for their stable capacitance over time and temperature, high accuracy, low losses at high frequencies, and ability to withstand high voltages. Mica capacitors are constructed by layering thin silver films on mica sheets and enclosing the stacked assembly in epoxy resin. Their applications include use in radio transmitters, power supplies, and other devices requiring precise capacitance in changing conditions.
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Introduction:
Construction of Mica Capacitor And
its Application
A capacitor is called as a condenser and earlier to that named as a
Permittor. It is a two terminal passive electrical component, used
to store electrical energy in an electric field. There are different
kinds of capacitors are available in the market and such one is
Mica Capacitors.
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Construction of Mica Capacitor And
its Application
What is a Mica Capacitor?
The term “Mica” is a collection of natural minerals.
Silver mica capacitor is a capacitor that uses the name mica as the
dielectric.
These capacitors are classified into two types
Silver mica capacitor
Damped mica capacitor.
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Construction of Mica Capacitor And
its Application
Silver mica capacitors are used in its place of clamped mica due to their
lower characteristics.
Mica capacitors are low loss capacitors which are used where the high
frequency is required and their value doesn’t change much over time.
What is a Mica Capacitor?
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Construction of Mica Capacitor And
its Application
What is a Mica Capacitor?
These capacitors are constant chemically, mechanically and electrically
due to its particular crystalline structure (typical layered structure).
This creates it achievable to produce thin sheets in the order of 0.025-
0.125 mm.
The most frequently used micas are Phlogopite mica and Muscovite
mica.
The high difference in raw material work leads to high cost required for
check & sorting.
Mica doesn’t respond with most acids, oil, water and solvents.
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Construction of Mica Capacitor And
its Application
Construction of Mica Capacitor
Silver Mica Capacitors are made by covering the silver directly on the
outside of mica.
Covering this is to obtain the desired capacitance.
After the layers are collected, electrodes are added & the assembly is
encapsulated.
Silver mica capacitors have a comparatively tiny capacitance value
(between a few pF, upto a few nF).
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Construction of Mica Capacitor And
its Application
Construction of Mica Capacitor
The largest capacitance capacitors can attain values of 1µF.
Silver mica capacitors are typically rated for voltages between 100 &
1000 volts.
There are particular high-voltage mica capacitors designed for RF TX
employ which are rated at up to 10 kV.
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Construction of Mica Capacitor And
its Application
How to Choose the Right Mica Capacitor
When you are selecting the right mica capacitors you can filter the
various attribute results so that you will be able to find the right silver
mica capacitors.
The following factors should check before choosing this capacitor
Lead Spacing -3.6 mm, 5.9 mm, 8.7 mm, 11.1 mm
Capacitance -2 pF, 22 pF, 47 pF, 100 pF, 470 pF
Rated Voltage-from 50 V to 1 kV
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Construction of Mica Capacitor And
its Application
Characteristics of Mica Capacitor
The characteristics of the mica capacitor include the following
Accuracy and Tolerance
Stability
Low losses
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Construction of Mica Capacitor And
its Application
Characteristics of Mica Capacitor
Accuracy and Tolerance
The values of smallest tolerance of a silver mica capacitor can be
as low as ±1%.
This is much superior than almost all other kinds of capacitors.
In contrast, positive ceramic capacitors can include tolerances of
up to ±20%.
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Construction of Mica Capacitor And
its Application
Characteristics of Mica Capacitor
Stability
These capacitors are very constant and very precise.
Their capacitance changes small over time.
This is due to the truth that there are no air spaces in the design
which might change over time.
Also, the assembly is guarded from other results by an epoxy resin.
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Construction of Mica Capacitor And
its Application
Characteristics of Mica Capacitor
This means that external effects like air humidity do not involve
mica capacitors.
Not only is their capacitance constant over time.
It’s also steady over an ample temperature, voltage & frequency
range.
The standard temperature coefficient is around 50 ppm/°C.
Stability
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Construction of Mica Capacitor And
its Application
Characteristics of Mica Capacitor
Low losses
These have low inductive and resistive losses.
The characteristics of these capacitors are generally frequency
independent.
Which permits for their use of high frequency.
These better characteristics come at a price: silver mica capacitors
are large and costly.
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Construction of Mica Capacitor And
its Application
Silver Mica Capacitor Properties
Silver mica capacitors are used frequently due to its features like high
level performance, superior in numerous areas than any other kind of
capacitor.
The particular properties of the mica capacitor are summarized below.
High accuracy
Temperature co-efficient
Value range
Low capacitance variation with voltage
High Q
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Construction of Mica Capacitor And
its Application
Advantages and Disadvantages of Mica Capacitor
The advantages and disadvantages of mica capacitors mainly include
• Stable capacitance.
• Operates at high temperatures.
• Withstand at very high voltages.
• Low losses.
• Highly accurate and Dielectric provides good insulation.
• High cost and Proper sealing is required.
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Construction of Mica Capacitor And
its Application
Applications for Mica Capacitors
The applications of mica capacitors can be found in a large range of
applications including the following
• Ripple filter and Decoupling for general electronic devices
• Resonant circuits
• Coupling circuits
• Time constant circuits
• High-power RF broadcast transmitters
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Construction of Mica Capacitor And
its Application
Applications for Mica Capacitors
The applications of mica capacitors can be found in a large range of
applications including the following
• Defense Electronic Devices
• Power transfer circuits for low-capacitance snubber applications
• Radio or TV transmitters
• Cable TV amplifiers
• High voltage inverter circuits
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Construction of Mica Capacitor And
its Application
Conclusion
From the above information finally we can conclude that, these
capacitors employ mica as the dielectric. They have high frequency
properties due to very stable over time, inductive losses and low
resistance. Mica capacitors are classified based on the different
properties like working voltage, required capacitance and current
handling capacity.