高性能LED显示器件封装材料的关键科学问题研究

High reliability and stability are the prerequisite for Light emitting diode (LED) packaging materials. Except high temperature resistance, high light transmittance, high light index of refraction and excellent interfacial bonding, epoxy encapsulation materials also have to fulfill the requirement of low internal stress, high hygrothemal stability and weatherability..In our previous works, the structure-property relationship and hygrothermal degradation mechanism of microelectronic packaging materials have been well studied. It has been found recently in our research that a combination of micro-sized flaky fillers and nanoparticles would dramatically enhance the moisture barring and ultraviolet shielding ability of the epoxy materials, furthermore, the properties of the LED packaging materials can be optimized by modulate the composition and structure of epoxy and modifiers, such as rigidity of main chain structure, polarity and crosslink density..The object of this project is to find the relationship of the thermal mechanical properties and anti-aging properties of epoxy encapsulation materials with their structure and composition by studying the interfacial bonding strength, internal stress, hygrothermal and UV aging of materials with different structure, curing stages, modifiers, and catalysts. The research works will focus on the preparation of high transparent material filled with micro- and nano-scaled particles, and investigate the synergistic effect of combined micro and nano-particles on the aging properties of filled materials through modulate the species, size and volume fraction of the two kinds of particles.

发光二极管(LED)显示器件的封装材料需要高度的可靠性和稳定性，不但要具备耐高温、高透光、高折光率以及良好的界面粘接等基本性能，而且要满足低应力、耐湿热老化以及高耐候等性能要求。.申请人前期系统地进行了电子封装材料的湿热老化机理以及结构与性能的关系研究。最近研究发现：在调控环氧及改性剂刚柔组成、极性和交联密度的基础上，通过微纳米复合填充料改性环氧基体，基于片状微米粒子的湿气阻隔和纳米粒子的紫外屏蔽效应，极大地提高了高透光LED封装材料的耐老化性能。.本项目拟建立环氧封装材料的组成和结构与内应力及耐老化性能的联系，重点研究微纳米复合填充料对材料老化性能的影响。通过调整环氧、改性剂及催化剂的组成和材料固化转化率，明晰材料结构与光电及耐老化性能的关联性；调控纳米粒子与基体树脂组成，确定高透光微纳米复合填充体系的制备方法；通过研究不同的微纳米复合填充料体系，建立微纳米复合填充与耐老化性能间的联系。

发光二极管(LED)显示器件的可靠性和稳定性与封装材料紧密相关，开发耐高温、高透光、高折光率、高耐候，并兼具低应力、耐湿热以及良好界面粘接的环氧树脂封装材料具有重要的意义。. 本项目分别对比了不同极性和柔顺性的环氧树脂及其混合物对热物理性能、界面粘接和吸湿溶胀等的影响；研究了环氧树脂、改性剂和填料的结构组成对封装材料内应力及耐光、湿、热老化性能的影响；研究了催化剂、固化工艺及转化率对材料基本性能及老化特性的影响。. 通过该项目研究确定了填料可以有效改善LED器件的性能及可靠性, 建立了LED器件的测试标准，该成果已在LED显示界获得广泛使用。明确了环氧树脂合适的刚柔比是实现LED高可靠性的基础,发现低极性柔性链的引入有效的降低了吸湿率及内应力。确定了环氧树脂固化机理及转化率对LED器件性能的显著影响,发现环氧树脂在90%左右的转化率对应于最优化性能。明确超支化高分子改性环氧树脂在提高韧性及加工性能的同时，降低了固化收缩率，因此有效的降低了封装料内应力。发现纳米填料与增韧剂改性树脂体系的协同作用，有效的提升了材料综合性能。