Take the small bench and talk about the preparation and physical performance of KOVAR parts sealing

u200bKovar® is a vacuum-melted Fe-Ni-Co low-expansion alloy. The chemical composition content is controlled within a very narrow range to ensure accurate and balanced thermal expansion performance. At the same time, strict quality control during the manufacturing process of KOVAR parts also ensures Balanced physical and mechanical properties are more suitable for deep drawing, stamping and various cutting processes. u200bMaterial use Kovar® is used for vacuum sealing of hard glass and ceramics, and is widely used in electron tubes, microwave tubes, transistors and diodes. On integrated circuits, it is used for flat integrated circuits and dual in-line packages. All parts made by Kovar® should be degassed and annealed in a humid hydrogen atmosphere. Hydrogen is injected into water at room temperature and gets wet through blisters. Care must be taken to prevent surface carbonization. The heat treatment furnace must have a cooling chamber that provides the same atmosphere. The heat treatment is carried out in the temperature range of 1540/2010°F (838/1099°C). The heat treatment time starts from a low temperature and rises to a high temperature in 20 minutes. Then the parts are moved to the cooling zone and cooled to 570°F (299° C) Take it out afterwards. When the metal is sealed with hard glass, it is recommended that the metal has an oxide film. The preferred oxide film is thin and tightly adsorbed on the metal surface. Such an oxide film can be heated to 1200/1290°F (650/700°C) in the atmosphere, and continue for a period of time until the dark gray surface layer turns into a light brown oxide film. Physical properties: specific gravity 8.36; density 0.3020lb/in3; thermal conductivity 120.0 BTU-in/hr/ft²/°F; coefficient of elasticity (E) 20.0 x 103 ksi; electrical resistance (70.0°F) 294.0 ohm-cir-mil/ft; Curie temperature is 815°F; melting point is 2640°F. Magnetic Kovar® alloys are magnetic below the Curie temperature, and the magnetic properties depend on heat treatment. The smaller the hardness, the higher the permeability and the smaller the hysteresis loss.u200b