在全球大规模推广使用LED照明的今天,使用寿命是制约LED发展的瓶颈,其中,封装材料的线膨胀系数对大功率LED的使用寿命具有重要的影响.由于大功率LED粘接层材料比其相邻材料的线膨胀系数大,在循环工作时各层之间的膨胀收缩不一致,导致层与层之间产生翘曲裂纹现象,从而影响LED的使用寿命.文中采用向环氧树脂(EP)中分别加入氮化硼(BN)、氮化铝(AlN)、碳化硅(SiC)微粉颗粒制备出3种——BN/EP、AlN/EP、SiC/EP复合材料,并对其进行对比分析.研究结果表明,BN/EP复合材料性能最佳,线膨胀系数可降至3.86×10-5 K-1.且当BN质量分数为55％时,导热系数达到1.598 W/(m· K),粘接强度为53.83 MPa.与纯环氧树脂相比,可使1 W LED芯片结温降低约29.6℃,寿命提高约2.2×104 h.
LED was widely applied around the world,but the development of LED was limited by its operational life.The linear expansion coefficient of the packaging materials had an important influence on the operational life of the high power LED.The expansion and shrinkage of the adhesive layer were inconsistent with the adjacent material because the linear expansion coefficient of the adhesive layer was larger than that of the adjacent material.This could caused the warping and cracking between layers and resulted to the serious reduction of the operational life of LED.In this study,powders of BN,AlN and SiC were added respectively into epoxy to prepare three epoxy composites (BN/EP,AlN/EP and SiC/EP composites).Comparative analysis shows that BN/EP composites are the optimalizing option,of which the linear expansion coefficient is 3.98 × 10-5 K-1.When the mass fraction of BN is 55％,the thermal conductivity is 1.598 W/(m· K) and the bonding strength is 53.83 MPa.Compared with the pure epoxy,the junction temperature reduces about 29.6 ℃ and the operation life improves about 22000 h.
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