深紫外LED封装制造中化学键合理论与实验研究

It is necessary to choose 3D ceramic substrate, achieve low temperature bonding and hermetic packaging for deep-ultraviolet (DUV) LED packaging. In this proposal, sintering-free ceramic (also called chemically bonded ceramics, CBC) was suggested to prepare 3D ceramic substrate and bond glass and ceramic at low temperature based on chemical bonding for DUV LED packaging. The proposed works include: 1) Reveal the flow law and boundary interaction of CBC slurry in mold cavity, combining Herschel-Bulkley fluid model and slurry dynamic test of sintering-free ceramic; 2) Study the interfacial bonding mechanism between CBC and different substrate (such as sintered ceramic, glass and metal, et al.) using ultrasonic reflection method and realize low temperature and robust bonding between glass cover and the ceramic substrate; 3) Packaging experiments and process optimization of DUV LED devices using CBC, so as to verify the above theory and model. Nowadays, DUV LEDs start to be used in some fields such as sterilization, water and air purification, new requirements such as high reliability and low cost are putted forward, so it is urgent to develop novel packaging materials and process for DUV LEDs. This proposal covers a typical fundamental cross-disciplinary problem abstracted from the processes and applications. The research achievements are expected to solve the problems of UV/DUC LED packaging, and boost the development of hermetic packaging and heterogeneous integration technology.

深紫外LED封装必须选用三维陶瓷基板，并实现低温键合与气密封装。本项目提出将免烧陶瓷（化学键合陶瓷）应用于深紫外LED封装，基于化学键合制备三维陶瓷基板，同时实现玻璃与陶瓷间低温键合。主要研究内容包括：1）结合赫切尔-巴尔克莱（H-B）模型与免烧陶瓷浆料动态测试，揭示浆料在模具腔内的流动规律及其与边界的相互作用；2）通过超声反射法研究免烧陶瓷与不同基体材料（烧结陶瓷、玻璃、金属）间的界面键合机理，实现玻璃盖板与陶瓷基板间低温高强度键合；3）应用免烧陶瓷的深紫外LED封装实验与工艺优化，验证上述理论和模型。目前，深紫外LED开始应用于杀菌消毒、空气与水体净化领域，对其器件性能（如可靠性、成本等）提出了更高要求，迫切需要研发新型的封装材料与工艺。本项目是一个典型的从工艺和应用中提出的基础交叉问题，其实施将有助于解决紫外/深紫外LED封装难题，并促进电子器件气密封装与异质集成技术发展。

深紫外LED由于芯片光电转换效率低，对水蒸汽等敏感，其封装必须选用含围坝结构的三维陶瓷基板，通过低温焊接（键合）实现气密封装。本项目基于化学键合原理，提出制备含免烧陶瓷围坝的三维陶瓷基板，并将其应用于深紫外LED封装。主要研究内容包括：1）系统分析了化学键合制备免烧陶瓷的固化原理与材料体系，开发了磷酸镁（MPC）和铝硅酸盐免烧陶瓷（Aluminosilicate Unsintered Ceramic, ASUC）两种免烧陶瓷浆料。其中ASUC由富含铝和硅元素的铝硅酸盐矿物颗粒与强碱溶液在室温下发生反应，生成具有一定强度的胶凝材料，具有低温固化、结合强度高、耐热性和酸碱腐蚀性好，结构致密等优点，但耐水性较差，提出采用添加磷酸硅提高了ASUC固化体耐水性；2）分别采用注浆法、溶模法和3D打印技术，制备出含免烧陶瓷围坝的三维陶瓷基板。结合赫切尔-巴尔克莱（H-B）模型与免烧陶瓷浆料动态测试，揭示了浆料在模具腔内的流动规律及其与边界的相互作用；研究了免烧陶瓷与不同基体材料（陶瓷、玻璃、金属）间的界面键合机理，实现了玻璃盖板与陶瓷基板间低温高强度键合；采用激光共聚焦显微镜测试了围坝结构形貌与加工精度；3）应用含免烧陶瓷围坝的三维陶瓷基板，采用免烧陶瓷浆料低温键合石英盖板与陶瓷基板，实现了深紫外LED封装。结果表明，采用免烧陶瓷技术封装的深紫外LED模组气密性良好，结合强度较高，可有效避免环境因素对芯片的不利影响。目前，随着新冠疫情的发展，深紫外LED广泛应用于空气、水体与物体表面杀菌消毒，对其器件性能（如可靠性、成本等）提出了更高要求，迫切需要研发新型的封装材料与工艺。本项目从深紫外LED封装工艺和应用中提出基础问题开展研究，涉及材料、热学、流体力学、光学、微纳制造等领域，项目实施部分解决了深紫外LED封装技术难题，促进了电子器件气密封装与异质集成技术发展。