植入式医疗器械已经成为临床治疗某些疾病的重要手段，而密封性是其最重要的特性之一。作为密封的关键部件，馈通性能的好坏直接决定了植入医疗器械的使用寿命。为了获得性能可靠的馈通，满足脑深部刺激器等设备的植入需要，本文研究了现有玻璃馈通成形过程中存在的缺陷并提出一系列的优化措施，分析了玻璃馈通的界面连接过程和应力分布，并对玻璃馈通的整体力学性能和密封可靠性进行测定和验证。同时，为适应植入医疗器械寿命延长的趋势，本文完成了陶瓷馈通的初步设计和实现。现有玻璃馈通的成形缺陷包括玻璃填充不充分、金属表面氧化污染和探针硬化等，主要是由工艺过程的热输入不足、污染性气氛含量过高和卡具结构不合理所致。玻璃对法兰和探针的润湿性是实现连接的前提，通过实验测定玻璃与Ti和Nb的润湿角分别为79°和57°，接头成形过程包括中间层形成、润湿和互相溶解。热膨胀系数会引起玻璃/金属封接界面的内应力，经计算和分析，玻璃/金属界面的径向的应力值较小，对密封的影响不大。所设计的陶瓷馈通采用Al2O3陶瓷和Au钎料，活性元素Ti在焊缝成形过程中起关键作用，焊缝内生成TiAux和Ti-O等。Au与Al2O3不润湿，但与表面金属化的Al2O3的润湿角为22°，金属化是实现陶瓷馈通成形的关键步骤。研究工作表明，通过优化后的设备和工艺，玻璃馈通的质量与合格率有明显提升；在中间层的作用下，玻璃馈通界面润湿性能良好；因热膨胀系数差异引起的玻璃馈通接头内应力较小，且玻璃/探针界面的拉应力可被探针的弹性变形抵消，玻璃/法兰界面的压应力有利于保持界面的紧密连接；探针与玻璃封接面的抗拉性能和小角度抗疲劳性能较好，玻璃馈通在特殊环境下的密封可靠性高，可满足长期植入的要求；陶瓷馈通的成形难点在于Au对Al2O3的润湿性，而陶瓷表面溅射Ti可解决这一问题，实现钎焊连接；根据设计的结构和材料，初步制成的陶瓷馈通满足密封性要求。
Implantable electrical stimulation device has become an important tool for the clinical treatment of certain diseases, and tightness is one of the most important characteristics. As a key component of sealed structure, feedthrough’s performance determines the life of implantable devices directly. To obtain reliable feedthrough, relying on the domestic neuro-stimulator implantation, defects during the forming process of glass feedthrough are studied and a series of optimization measures are put forward in this paper. This paper also analyzes the interface connection and internal stress distribution of glass feedthrough, then its mechanical properties are measured and sealing reliability is verified. Meanwhile, in order to meet the demand for prolonging the life of implantable devices, a ceramic insulator feedthrough is designed.Defects of glass feedthrough include insufficient glass-filled situation, oxidation pollution on metal surface and hardening of the pins, which are mainly due to the insufficient heat input, high content of contaminated atmosphere and unsuitable fixture structure during the forming process. Wettability of glass/flange and glass/pin interface is the premise to achieve the connection, and by experimental determination the wetting angles of glass/Ti and glass/Nb are 79° and 57° respectively. The joining process includes forming an intermediate layer, wetting and mutual dissolving of the base materials. The coefficient of thermal expansion may cause internal stress at the interface of glass feedthrough, but the radial stress value is not enough to damage the sealing through calculation and analysis. The designed ceramic feedthrough adopts Al2O3 and Au solder, where Ti plays a key role in the weld formation process. Au can’t wet Al2O3, but with surface-metallized Al2O3 a wetting angle of 22° can be obtained, which shows that metallization is the key step during the ceramic feedthrough assembly forming.Research work of this paper shows that with optimization of equipment and process, the quality and finished proportion rate of glass feedthrough are improved significantly. Under the action of intermediate layer, glass feedthrough gets well-wetting interfaces. Small joint stress is caused by the differences of thermal expansion coefficient. Tensile stress of the glass/pins interface can be offset by the elastic deformation of pins and compressive stress of the glass/flange interface is conductive to the sealing. Tensile properties and fatigue resistance in small angular range in the interface of glass/pins are strong. Glass feedthrough can hold a high reliability sealed joint in special circumstances, which meets the need of long-term implantation. The difficulty of ceramic feedthrough forming lies in the wettability of Au and Al2O3, but the Ti coating metallization on the surface of ceramic can resolve the problem to achieve a good bonding connection. With the design of structure and materials of ceramic feedthrouhg, it can reach a satisfied leakage rate, which meets the sealing requirements and means a wide application prospect in the implantable medical device field.
