LED由于具有使用时间长、节约能源、绿色环保等优点,广泛应用于显示和照明领域,例如大规模显示屏和白光照明等。目前LED器件广泛使用环氧树脂作为封装材料,但由于其较大的热膨胀系数,在LED使用中容易因芯片发热与LED内部的芯片及金属部件热膨胀行为不一致,从而可能损坏LED芯片,导致器件失效等问题。为降低LED封装材料的热膨胀系数,以微波水热法制备的负热膨胀材料磷酸钨锆(ZWP)粉末为填料,填充到双酚A环氧树脂中制备ZWP/环氧复合材料,同时探究微波水热反应条件对ZWP粉末的形态和结构的影响,并测试了不同填料含量时封装材料的热膨胀效应和光学、热机械性能等。研究结果表明,与普通水热法相比,微波水热法制备的ZWP粉末的尺寸小,粒径分布均匀,具有更优良的负热膨胀性能;ZWP粉末对环氧树脂复合材料的热膨胀性能有显著的改善,且随ZWP粉末含量的增加,改善效果逐渐增强,其中40% ZWP含量的复合材料在玻璃态(30～90℃)时热膨胀系数下降约42.7%(约30.5×10-6/℃),10% ZWP含量的环氧复合材料的综合性能较优。
Due to the advantages of long use time,energy saving and environmental protection,LED develops rapidly and is widely applied in display and lighting fields such as large scale display and white light illumination.Nowadays,epoxy resin is one of the most common used packaging materials for LED devices because of its low cost and excellent properties.However,it's characteristic of large thermal expansion coefficient (CTE) usually causes inconsistency of thermal expansion behaviors between the chip or other metal parts inside the LED and packaging materials during using,which may cause damage to the LED chip and finally resulting in the failure of devices or other reliability issues.In order to reduce the thermal expansion coefficient of LED packaging materials,negative thermal expansion powder of tungsten zirconium phosphate (ZWP) was synthesized by microwave hydrothermal method,which was filled into bisphenol A epoxy resin to prepare ZWP/E-51 epoxy composites with different filling content.The effect of microwave hydrothermal process on the morphology,structure and property of ZWP powder was studied.And the thermal expansion properties,optical and thermodynamic properties of epoxy composites under different filling contents were also studied.The main results showed that:(1)compared with hydrothermal method,the ZWP powder prepared by microwave hydrothermal method was smaller and more uniform in size,giving better property of negative thermal expansion;(2)With the increment of ZWP powder,the thermal expansion property of ZWP/E-51 was improved significantly,and a 40wt% ZWP loading gave a 42.7% (about 30.5×10-6/℃) reduction of CTE at a temperature range of 30～90℃.And in addition,ZWP/epoxy composite with 10wt% loading showed better comprehensive properties.
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