How does multi-layer ceramic capacitor (MLCC) achieve a volume as small as a grain of sand?

2024-03-24

The reason why multi-layer ceramic capacitors (MLCCs) can achieve a volume as small as a grain of sand lies primarily in their special structure and manufacturing processes. Here are some key factors:

Multi-layer structure: MLCCs are made by stacking multiple thin ceramic layers. This multi-layer structure allows them to accommodate more capacitors in the same volume, thereby increasing the capacitance. Additionally, the multi-layer structure helps to reduce the size of individual capacitors.

High-density manufacturing processes: The manufacturing process of MLCCs employs highly precise techniques to stack as many capacitor layers as possible in tiny spaces. This includes precise preparation of ceramic materials, thin-film deposition, pressing, sintering, and other process steps.

These capacitors use a ceramic material as the insulating dielectric between the anode and cathode plates. Ceramic powder, such as barium titanate, is mixed with a binding material to form a slurry. This slurry is then thinly applied to a thin metal sheet. Alternatively, metallic paste can be applied to the ceramic slurry.

The ceramic and metal layers are then stacked together, mechanically pressed at high temperatures, and cut into small discs or rectangles to form capacitor ‘chips.’ The external dimensions of the chips, as well as the layer distances, drive the capacitance values of the capacitor.

These chips are fired in a kiln at high temperatures to remove the binder, leaving only the ceramic and metal materials in the chips. The firing process can reduce the size of the unfired chips by 30% or more, depending on the materials used in the manufacturing process.

Once fired, the chips are sintered with termination ends that connect alternating layers of the electrodes to each terminal. These terminals are electroplated to provide a suitable surface for end-use soldering and placement on a PCB. After electroplating, the capacitors are ready for testing a capacitance verification. The diagram shows below:

Micro-sized electrode design: MLCCs use micro-sized electrodes to connect the various ceramic layers. These micro-sized electrodes are typically manufactured using highly precise thin-film metal techniques, enabling electrode connections in tiny spaces and reducing overall size.

Material optimization: The ceramic materials and electrode materials used in MLCCs are carefully optimized to ensure good electrical performance even in small sizes.

Considering these factors, multi-layer ceramic capacitors can provide significant capacitance in a volume as small as a grain of sand, making them an essential component widely used in modern electronic devices.

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