InSealing are specialized in ceramic-to-metal sealing for years. As we all know, ceramic-to-metal sealing components are widely used in the fields of new energy vehicles, electronics, semiconductor packaging and IGBT modules. The main products are ceramic structure parts and ceramic substrates. With the increase in market demand and the continuous emergence of new materials, ceramic seal connectors, ceramic substrates and other series of products have achieved scale. Therefore, the sealing process of ceramics and metal with high strength, high air density, and high reliability is essential.
But do you know what is the difficulty of ceramic-to-metal seal?
First, the reliable connection between ceramic and metal is the key to advancing the application of ceramic materials. The biggest difficulty in the sealing process of ceramic and metal is that the value of thermal expansion coefficient of ceramic and metal is very different (the thermal expansion of metal is higher than ceramic). After the connection is completed, a large residual stress will be generated at the seal interface, which reduces the intensity of the joints.
So good ceramic and metal seal, the sealing should meet the following requirements:
1. It has a good vacuum air tight;
2. Have a certain mechanical strength;
3. Under the condition that the working temperature is long for a long time, its electrical performance and mechanical performance should remain unchanged;
4. Can withstand the sharp temperature changes;
5. The tolerance of the sealing size is precise.
At present, the more widely used methods of ceramic and metal connection are mainly welding connection technology. Its product performance is stable, the process reliability is high, and the production cost is reasonable. The following mainly introduces three types of ceramic sealing technology.
1. sintering metal powder method
The sintering metal powder method refers to the metallic treatment of the ceramic surface in a specific temperature and atmosphere, so that the ceramic parts have metallic properties. Then use the low melting point solder to connect the metallized ceramic with the metal.
(1) Metallized layer preparation
(2) Ni plating on the surface of the metallized layer
The commonly used Ni plating methods are electroplating and electroless plating.
(3) Sealing of metallized ceramics and metals
2. Active metal brazing
Active metal brazing (AMB) is an active element in the material to form a reaction layer on the ceramic surface through chemical reactions to improve the wetting of the ingredients on the ceramic surface, so as to perform chemicals between ceramics and metal Combine.
3. Direct Bonded Copper, DBC
This process is at high temperature and certain oxygen pressure conditions, which will oxidize the CU surface to form a common crystal fluid phase wet ceramic base and CU. At high temperature, a chemical reaction will form a very thin transition layer between copper and ceramics. That is to realize the connection between metal and ceramics.
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