High Thermal Conductivity Insulators Is Essential For Accurate Measurement

The ability of a material to transfer thermal energy is measured as its thermal conductivity (K, l or k-value). Materials with high thermal conductivity transmit heat easily and are used in applications where rapid heat transfer is required. Low thermal conductivity materials act as effective insulators, keeping thermal energy trapped inside the material.

Efficient Thermal Management in Electronics varies with temperature and changes when the material is exposed to varying temperatures. This makes it difficult to predict the performance of a material in different environments.

To solve this challenge, researchers at MIT have developed a thermal valve that can vary the material's thermal conductivity on demand. The valve is based on a simple device that can alter the material's microstructure by changing its density, making it possible to "tune" its conductivity. The results have the potential to open up new opportunities for controllable insulation, harvesting waste heat and other applications that require varying thermal conductivity.

The thermal performance of a material can be influenced by its composition, density, chemistry and structure. This is especially true for electrically conductive materials, which must meet a variety of requirements in order to function correctly. Currently, insulating thermally conductive materials are primarily composites filled with ceramic particles, but these materials struggle to meet the requirements of power electronic devices due to their insufficient conductive properties and high density.

This problem can be overcome by using a material with lower filler density, lowering the binder content or changing the resin. In addition, using a material with higher thermal conductivity, like copper or aluminum, can also be beneficial. However, these approaches come with the drawback that they have a negative impact on the material's strength and corrosion resistance.

Fortunately, researchers have recently developed a material that is both thermally conductive and electrically insulated. The material is a polymer elastomer reinforced with glass fiber, which not only improves the thermal conductivity of the material, but it also has excellent tear resistance and high breakdown voltage. The resulting product is an ideal solution for power electronics and other high-temperature applications that need to avoid breakage or leakage of internal components.

The key to the success of this new material lies in the fact that it is able to reduce both the thermal and electrical resistance of the insulating layer by a factor of 10. It achieves this by reducing the number of air pockets within the insulator, which decreases its bulk density. This is achieved by introducing boron nitride nanosheets into the polymer matrix. The boron nitride nanosheets enhance the material's thermal conductivity while simultaneously improving its flexibility, strength and electrical insulation. C-Therm's advanced MTPS sensor is capable of measuring thermal conductivity in these highly insulating materials at elevated temperatures without affecting the integrity of the sensor. This is possible because the sensor uses an alumina dielectric and ceramic sealant to provide protection against softening or delamination in standard handling conditions. The alumina sensor chip ensures that the sensors remain rigid and in contact with the surface of the insulation at all times, which is essential for accurate measurement.