If you’ve ever wondered about how ceramic chip capacitors (MLCCs) are made, check out this page from Johnson Dielectrics:
The process of making ceramic capacitors involves many steps.
- Mixing: Ceramic powder is mixed with binder and solvents to create the slurry, this makes it easy to process the material.
- Tape Casting: The slurry is poured onto conveyor belt inside a drying oven, resulting in the dry ceramic tape. This is then cut into square pieces called sheets. The thickness of the sheet determines the voltage rating of the capacitor.
- Screen Printing and Stacking: The electrode ink is made from a metal powder that is mixed with solvents and ceramic material to make the electrode ink. The electrodes are now printed onto the ceramic sheets using a screen printing process. This is similar to a tshirt printing process. After that the sheets are stacked to create a multilayer structure.
- Lamination: Pressure is applied to the stack to fuse all the separate layers, this created a monolithic structure. This is called a bar.
- Cutting: The bar is cut into all the separate capacitors. The parts are now in what is called a ‘green’ state. The smaller the size, the more parts there are in a bar.
- Firing: The parts are fired in kilns with slow moving conveyor belts. The temperature profile is very important to the characteristics of the capacitors.
- Termination: The termination provides the first layer of electrical and mechanical connection to the capacitor. Metal powder is mixed with solvents and glass frit to create the termination ink. Each terminal of the capacitor is then dipped in the ink and the parts are fired in kilns.
- Plating: Using an electroplating process, the termination is plated with a layer of nickel and then a layer of tin. The nickel is a barrier layer between the termination and the tin plating. The tin is used to prevent the nickel from oxidizing.
- Testing: The parts are tested and sorted to their correct capacitance tolerances.
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