What is dielectric constant?
Does larger dielectric constant mean better insulation?

When hearing “dielectric constant”, many friends may think of “insulation”, and subconsciously think that the larger the dielectric constant, the better the insulation. But is this really the case? Let’s talk about this today.

To understand what the dielectric constant is?
In simple terms, the dielectric constant is an indicator of a material’s ability to store electrical energy. It reflects the material’s ability to weaken the electric field under the action of an external electric field. To put it in a figurative way, it’s like a sponge. The larger the dielectric constant, the stronger the sponge’s ability to absorb water. The external electric field is like water. The more it is adsorbed by the material, the weaker the electric field strength will naturally be.

So what is the relationship between the dielectric constant and insulation?
There is indeed a relationship between the two, but it is not a simple proportional relationship.
Specifically: The dielectric constant is an indicator of the material’s polarization ability. The stronger the polarization ability, the larger the dielectric constant. The polarization ability mainly depends on the distribution of charges inside the material and the response ability of these charges under the action of the electric field. Insulation refers to the ability of a material to resist the passage of current, which mainly depends on the resistivity inside the material. The greater the resistivity, the less likely the material is to conduct electricity, and the better the insulation performance.

The question is, how are the large dielectric constant and good insulation related?

1. Materials with large dielectric constants are more likely to polarize internal charges, which means that it is easier to store electrical energy, which is indeed a manifestation of good insulation performance. For example, materials such as ceramics and glass have relatively large dielectric constants and also show good insulation performance.

2. However, a large dielectric constant does not necessarily mean good insulation. Because some materials, although the dielectric constant is very high, may have some defects inside, such as impurities, voids, etc., which will reduce the resistivity of the material and thus reduce its insulation performance. Therefore, there is some “ambiguous” relationship between a large dielectric constant and good insulation, and it is not simply proportional.

For example:

To summarize: The dielectric constant and insulation are not absolutely proportional. The insulation performance of the material is affected by many factors, including dielectric constant, resistivity, defects, etc. Therefore, when selecting materials, various factors should be considered comprehensively, and the insulation performance of the material cannot be judged solely by the dielectric constant.