Effect of composite surface treatment on heat dissipation of LEDs

A three-layered structure comprising two layers of substrates with an adhesive layer at the center is introduced to improve heat dissipation of light-emitting diodes (LEDs). The adhesive layer is a type of treated composite composed of three components: hexagonal boron nitride (H-BN), epoxy resin (EP), and silane coupling agent. EP can be better positioned as a filler agent by using H-BN, thereby increasing adhesion. Introducing the silane coupling agent builds a heat conducting path from H-BN to EP, which effectively increases the thermal conductivity of the adhesive layer. In addition, the substrate surface treatment acts as an attraction agent and a catalyst that increases the interstitial between the composite and treated substrate surface. When the weight fraction of H-BN is 75%, the thermal conductivity of the treated composites at the center reaches 11.536 W.m(-1) K-1, which is 38.57% higher than that of untreated H-BN/EP composites and 49 times that of EP. The thermal conductivity and adhesion strength of surface-treated three-layered structure are 9.571 W.m(-1) K-1 and 56.60 MPa, respectively. Analysis of the thermal stability of the three-layered structure shows that surface-treated structures are more durable than surface-untreated structures. (C) 2015 Elsevier Ltd. All rights reserved.