The introduction of KOVAR parts, don't come over and take a look.

u200bKOVAR parts, as a commonly used metal housing material in the electronic packaging industry, have a linear expansion coefficient close to that of the molybdenum group glass, and can produce less sealing stress during the sealing (melting) process with the molybdenum group glass. So as to obtain good airtightness, in order to make the metal tube and shell to achieve airtight sealing, in the entire sealing process, the annealing process undoubtedly plays an important role in connecting the previous and the next, it not only eliminates the metal parts in the predecessor—— The internal stress generated in the manufacturing process also prepares the material structure for the implementation of the metal parts in the subsequent process-the sealing process. u200bu200bThe main purpose of the annealing of the Kovar shell before sealing is to: (1) Eliminate mechanical processing stress. When Kovar undergoes plastic deformation during cold working, about 10% to 15% of the applied energy is converted into internal energy, which is commonly referred to as internal stress, so that the Kovar material structure is in an unstable state. Under this condition, it can be maintained for a long time without significant changes. Once it is heated, a series of changes in structure and properties will occur, and the material structure tends to a stable state. This change in structure and properties, especially changes in the structure of the structure, is reflected on the sealing surface. The tensile stress on the molybdenum group glass during high temperature sealing may cause the glass to produce small cracks and leak; (2) Eliminate work hardening. In the process of cold working, manufacturing and forming of Kovar parts, the internal material structure has defects such as grain elongation and grain breakage, which greatly increases crystal defects and increases the dislocation density. The smaller the distance between the dislocation and the dislocation, the greater the interference between each other, and the greater the distortion of the surrounding lattice. Each dislocation line has a stress field, and the dislocation and the dislocation pass through each The interaction of the stress field causes the hardness and elasticity of Kovar to increase, while the plasticity decreases, that is, work hardening. If the work hardening is not eliminated, the stress field of the interaction between dislocations and dislocations will be broken due to crystal recovery or recrystallization during high-temperature sealing, and the balance will be lost. This also affects the sealing of metal and glass. Certain stress effects;