Ceramic Chip Capacitor
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Our Ceramic Chip Capacitor Products
0.068uF 50V X7R Cap Ceramic Capacitor SMD 0603
Integrated Circuits MLCC Multilayer Ceramic Capacitor
What are ceramic capacitors?
A ceramic capacitor uses a ceramic material as the dielectric. Ceramics were one of the first materials to be used in the producion of capacitors, as it was a known insulator. Many geometries were used in ceramic capacitors, of which some, like ceramic tubular capacitors and barrier layer capacitors are obsolete today due to their size, parasitic effects or electrical characteristics. The types of ceramic capacitors most often used in modern electronics are the multi-layer ceramic capacitor, otherwise named ceramic multi-layer chip capacitor (MLCC) and the ceramic disc capacitor. MLCCs are the most produced capacitors with a quantity of approximately 1000 billion devices per year. They are made in SMD (surface-mounted) technology and are widely used due to their small size. Ceramic capacitors are usually made with very small capacitance values, typically between 1nF and 1µF, although values up to 100µF are possible. Ceramic capacitors are also very small in size and have a low maximum rated voltage. They are not polarized, which means that they may be safely connected to an AC source. Ceramic capacitors have a great frequency response due to low parasitic effects such as resistance or inductance.
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.
- At this point the capacitor manufacturing is complete. The parts could be packaged on tape and reel after this process or shipped as bulk.
Applications for ceramic capacitors
Having in mind that MLCCs are the most widely produced capacitor in the electronics industry, it goes without saying that there are countless applications for these capacitors. An interesting high-precision, high-power application is a resonant circuit in transmitter stations. Class 2 high-power capacitors are used in high voltage laser power supplies, power circuit breakers, induction furnaces etc. Small-form SMD (surface mount) capacitors are often used in printed circuit boards and high density applications use capacitors which are comparable to the size of a grain of sand. They are also used in DC-DC converters which put a lot of stress on the components in the form of high frequencies and high levels of electrical noise. Ceramic capacitors can also be used as a general purpose capacitor, since they are not polarized and are available in a large variety of capacitances, voltage ratings and sizes. Many hobbyists, especially in the field of robotics, are familiar with ceramic disc capacitors used across brush DC motors to minimize RF noise.