What Dielectrics Are & Why You Might Need Them
Written by Marketing Manager Emily Waterhouse
What they are
Dielectrics are insulators, which would be materials like glass and plastic. Insulators are poor conductors of electricity, heat, and sound. Insulators are used to stop the flow of electricity where it isn’t needed or where it could potentially be very dangerous, such as when its through our bodies.
Do you know people that live and breathe electrical tape? My boyfriend uses it for everything, even as a bandaid!
Important properties of a dielectric is its ability to support an electric charge, or electrostatic field, while dissolving minimal energy in the form of heat. The less energy lost in a heat form the more effective a dielectric material becomes. This is known as dielectric loss.
Another property to be aware of is the dielectric constant, which is the extent to which a substance concentrates the electrostatic lines of flux. Which is a way to scientific way of saying the measure of a material’s ability to insulate charges from each other.
Materials with low dielectric constants include perfect vacuum, dry air, and most pure, dry gases such as helium and nitrogen. Materials with a moderate dielectric constant include ceramic, distilled water, paper, plastic, and glass. High dielectric constants are usually metal oxides. This might be why we are told not to hold metal when it’s thunder-storming – it’s a great conductor and will definitely shock ya!
To be clear, low dielectric constant (or high dielectric strength) means it’s a good insulator and is a poor conductor of electricity, heat, or sound. High dielectric constants (or low dielectric strength) are poor insulators and great electricity conductors.
If the voltage of a dielectric material becomes too intense the material will start to conduct currents. This is known as a dielectric breakdown. In components that use gases or liquids as the dielectric, this condition reverses itself if the voltage decreases below its critical point. But in components containing solid dielectrics, dielectric breakdowns will end in permanent damage.
Why You Might Want a Dielectric Coating
For example, the plastic coating you find on an electrical cord is an insulator. Or the glass / ceramic plates used to support power lines to keep them from shorting out are also insulators. Basically anytime a nonmetallic solid is used in an electrical device it’s an insulator. Actually, the only time the word “dielectric” is used is in reference to the nonconducting layer of a capacitor. It stops electrical currents, really. It can also stop 2 currents from colliding. Say for example, you have 50 pins all next to each other. 25 give off current A, and 25 give off current B. A dielectric coating can stop currents A & B from colliding and shorting out the entire board.
Our Parlyene Conformal Coating has extremely high dielectric strength. While also having exceptional electrical insulation properties that is applied in a thin, pin-free film. This unique combo allows Parylene to be used as a precise dielectric layer in a variety of applications. Such as coating catheters, or pins on PCB’s.
Parylene’s breakdown voltage is determined by the coating’s thickness. Which you can read how we change thickness, here. Another reason Parylene is a unique dielectric material is it has a low dissipation factor, and high surface and volume resistivity that remains constant with any temperature changes.
Parylene is considered an insulator with high dielectric strength that is used to protect highly conductive components that should not collide with other components. It’s also one of the best options available to add to a wide variety of substances.