High Thermal Conductivity Insulators Suitable Purpose For Heat Transfer
Due to the continuous evolution toward miniaturization, higher integration and increasing power density in modern electric equipment and electronic devices, heat dissipation becomes a challenging issue for them. If the accumulated heat is not effectively dissipated, it will cause overheating which not only reduces the efficiency and reliability of the device but also poses fire risks. Therefore, Efficient Thermal Management in Electronics materials with good mechanical, electrical insulation and low breakdown voltage are highly sought after.
Conventional thermal pads and thermally conductive tapes are not suitable for the purpose because they cannot meet the demands of high-power applications in terms of both temperature resistance and electrical conductivity. As a result, they are easily brittle and can fail to perform as intended when exposed to extreme high temperatures and pressures.
For this reason, a new thermally conductive material with controlled thermal conductivity is required to address these issues. The team of MIT researchers led by Bilge Yildiz PhD ’18 and Gang Chen along with recent graduates Qiyang Lu PhD ’18 and Samuel Huberman PhD ’18, have successfully developed a material that can alter its thermal conductivity on demand. This advance could open the door for controllable insulation in smart windows, walls and even clothing to harvest energy from waste heat.
The key to the high-performance material is the hybrid of SUPE and boron nitride (BN), which is capable of boosting the electrical conductivity of the SUPE by reducing its dielectric loss factor. In addition, BN enhances the mechanical performance of the SUPE by suppressing its fracture and bending.
In this approach, the BN is deposited onto a thin layer of SUPE by spin coating. Afterwards, the layer is thermally bonded to the underlying surface of the insulation using plasma-enhanced chemical vapor deposition (PECVD). The result is a robust composite with superior conductivity and mechanical properties.
The boron nitride is also capable of raising the break down voltage of the SUPE by reducing its dielectric constant k, which is a function of temperature. As a result, the composite has an improved electrical resistance at high temperatures.
Moreover, the insulator can be tuned in its thermal conductivity by controlling the boron nitride content. For example, by varying the BN concentration, the thermal conductivity of the composite can be varied between 0.17 W m-1 K-1 and 4 W m-1 K-1.
In addition, the insulator can be protected from moisture by limiting the ingress of water. By using proper detailing and installation methods, the insulation can ensure that moisture levels remain below 95% RH, which will prevent damage to the material. This will increase its lifespan and performance.