Recycled and flexible boron nitride heat spread film with high thermal conductivity

In the rapidly advancing information age, the demand for highly thermally conductive and insulating materials is increasing due to the miniaturization and high-power density of electronic devices. Therefore, large-scale production of highly thermally conductive and insulating materials plays an important role in alleviating the pressure of industrial production. Herein, highly thermally conductive and insulating heat spread films combining polyvinyl butyral (PVB) and hexagonal boron nitride (h-BN) are prepared via tape-casting and vacuum hot-pressing technology. The vacuum hot-pressing technology is superior to produce densely packed and uniformly oriented h-BN fillers. Accordingly, the in-plane thermal conductivity of the vacuum hot-pressed boron nitride heat spreader (BNHS-VHP) is as high as 73.38 W m-1 K-1, which represents a nearly 400% increase over the boron nitride heat spreader (BNHS) (similar to 18.46 W m-1 K-1). The BNHS-VHP as a heat spreading film between the system on chip (SoC) and the heat sink can effectively reduce the temperature of a phone's motherboard. Furthermore, h-BN is easily recyclable due to the solubility of the PVB matrix in ethanol. The thermal transportation and mechanical properties of the heat spreader with recycled h-BN filler are similar to those of the heat spreader with the original h-BN filler. This approach provides valuable experience for practical production and reduces the cost of raw materials for industrial manufacturing. The large-scale production of boron nitride (BN)/polyvinyl butyral (PVB) composite films with excellent thermal conductivity and recyclable properties was achieved through tape-casting and vacuum hot-pressing techniques.