【作者】 万正国；

【导师】 贾虎生；

【作者基本信息】 太原理工大学 ， 材料学， 2008， 硕士

【摘要】 环氧树脂是一种用途非常广泛的热固性树脂,在电子行业作为封装材料使用。环氧树脂吸湿性好、热膨胀系数小、耐化学腐蚀,但其导热性、光学性能、热稳定性尚有不足之处,因而作为封装村料受到了一定限制。本文采用二氧化硅、纳米氧化镁对环氧树脂进行改性,以期用于发光二极管（LED）封装材料。本文采用高分子保护沉淀法制备了纳米氧化镁。以氯化镁为原料,碳酸钠作沉淀剂,聚乙烯醇（PVA）为高分子保护剂,制备出氧化镁的前驱物,经离心、真空干燥,在973K下锻烧,制得了纳米氧化镁粉体,平均粒径为40～50nm,面心立方结构,基本呈球形,分散性较好。本文通过填充SiO₂提高了固化物的导热率和耐热性。采用导热仪和热分析仪研究对其导热性、耐热性能进行了表征。实验结果表明,SiO₂的体积分数的增加,固化物导热增加,当SiO₂的体积分数达到50%时,导热率达到0.677 W·m^-1·K^-1,约为未添加SiO₂的2.5倍。同时耐热性有所提高,其中初始分解温度提14K,终止分解温度提高了19K。研究了环氧树脂的组分、固化剂、稀释剂、热氧稳定剂及工艺温度对固化物透明性的影响,得到了光学性能很好的固化物。采用纳米氧化镁对环氧树脂AB胶进行填充改性,实验证实,固化反应后的产物,导热、耐热及光学透明性能均有所增加。随MgO的含量增加,固化物的热导率相应增加;透光性能随MgO含量的增加呈现极值变化,填充量为0.2%时,固化物的透光率最大,继续提高MgO的含量固化物的透光率下降;添加MgO填料同时改善了热稳定性,初始分解温度提高。更多还原

【Abstract】 Epoxide resin is one of the thermosetting resins that has been widely applied in various areas,especially in the electronic packaging materials.It has a low coefficient of thermal expansion,good moisture absorption,and strong resistance from chemical corrosion.However,some of disadvantages such as low thermal conductivity and instability as well as optical property have limited its applications in large power LED devices.To solve this problem,this work focused on developing a modification method to improve the performance of epoxide resin so as to use it as a packaging material for LED devices.In this work,nano-MgO was prepared by using a PVA protection precipitation method.At first,MgCl₂ was used as a raw material,Na₂CO₃ as a precipitating agent,water as a reaction media and the PVA as protection reagent to produce a precursor of magnesium carbonate.Then,magnesium oxide nanoparticles were prepared by calcinating the magnesium hydroxide at 973K after being dehydrated by means of multi-freeze centrifugal and vacuum drying at a given constant temperature.The as-prepared products were spherical particles with average crystalline size about 40-50nm and had a good crystallinity and high dispersibility.The solidified product after modification was characterized using a laser diffraction heat conductivity coefficient instrument and a TG analyzer.When the volume fraction of SiO₂ was 50%,the coefficient of heat conductivity was 0.677 W·m^-1·K^-1,about 2.5 times that without adding SiO₂.Meanwhile,its decomposition temperature increased by 14K at the initial point,and 19K at the end point.The thermal conductivity,heat resistance,and optical transparence of nano-MgO modify epoxide resin were measured.It was found that heat conductivity of AB glue increased with increasing MgO percentage.When the mass fraction of MgO was 0.2%,the luminousness of solidified products reached the maximum,and then the luminousness decreased with further increasing MgO content.Meanwhile,adding MgO also improved the heat stability and increased the decomposition temperature of epoxide resin.更多还原