subject: Graphene-Based One-Component Low-Temperature Thermosetting Thermal Conductive Epoxy Encapsulant
Author: Yao-Wei, Shih
Graphene is a two-dimensional planar structure composed of a single layer of carbon atoms, with a thermal conductivity of up to 3000 W/mK at room temperature. Due to its excellent thermal conductivity, it is a highly promising heat dissipation material. However, the π–π electronic interactions between the planar structures lead to aggregation, making graphene dispersion a major challenge.
In contrast, common fillers such as spherical aluminum oxide (Al₂O₃) and zinc oxide (ZnO) typically have a thermal conductivity of 30–40 W/mK, along with advantages such as narrow particle size distribution, good size stability, and the ability to enhance packing density. This product combines these benefits by utilizing coating technology to encapsulate aluminum oxide with a layer of graphene, effectively improving the dispersion of graphene and ensuring the fluidity of the adhesive (Figure 1).
Additionally, graphene is an excellent conductive material with a resistivity of approximately 10⁻⁶ Ω·cm. The addition of a certain proportion of graphene to the adhesive may form a conductive pathway, imparting electrical conductivity. Therefore, determining the critical concentration requires measuring volume resistivity.
A thermally conductive encapsulant containing 3 wt% Al₂O₃@graphene, after curing at 100°C for 50 minutes, was tested according to ASTM D5470 standards, yielding a thermal conductivity exceeding 5 W/mK. Its viscosity at 25°C is approximately 150,000–200,000 cps, making it easy to handle and apply.
As shown in the TGA spectrum (Figure 2), the product’s filler loading reaches 89%, and its thermal decomposition temperature is as high as 398°C, indicating excellent thermal stability. According to ASTM D257 "Standard Test Methods for DC Resistance or Conductance of Insulating Materials," the measured volume resistivity is 2–6 × 10¹⁵ Ω·cm, ensuring high thermal conductivity and insulation performance (Figure 3). This product can be used as a heat transfer medium in electronic components, enhancing the advantages of epoxy encapsulants.
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Figure 1: Al₂O₃@Graphene Significantly Reduces Viscosity
| Figure 2: TGA Analysis – Filler Loading Reaches 89% |
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Figure 3: Thermal Conductive Encapsulant with 3 wt% Al₂O₃@Graphene Achieves Thermal Conductivity Greater Than 5 W/mK |
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