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Ceramic PCBs - Thick/Thin/DCB Ceramics
Posted on 24/11/2017

If you are looking for small volume electronic products that must be highly reliable while operating at high frequencies and high insulation in environments with high pressure, high temperature, and high pressure, Metal Core PCBs (MCPCBs) may be a good choice. However, there is other alternative — a ceramic PCB.

Characteristics

A brief overview of the basic structure of ceramic PCBs offers an insight into why they offer such excellent performance. Usually, ceramic PCBs are made from 96-98% Alumina (Al2O3), Aluminum Nitride (AIN), or Beryllium Oxide (BeO). Although for thin or thick film technology, silver palladium (AgPd) is preferred as the conductor material. For the requirement of direct copper bonding, copper is used. Ceramic PCBs can operate in the temperature range of -55°C to +850°C, and they have excellent thermal conductivity ranging from 24-250 W/m-K, depending on whether the ceramic material is Alumina, Aluminum Nitride, or Beryllium Oxide. Ceramic materials exhibit great compression strengths of above 7000 N/cm2, with breakdown voltages of up to 28 KV/mm for 1.0mm thickness. The thermal expansion coefficient under operating temperatures of 50-200°C is about 7.4 ppm/K.

Types of Ceramic PCBs

Depending on the manufacturing method, three basic types of ceramic boards are available in the market:

  • Thick Film Ceramic Boards
  • Thin Film Ceramic Boards
  • DCB Ceramic Boards

Thick Film Ceramic Boards

These are so called because of the thickness of their conductor layer, which may exceed 10 microns, but not more than 13 microns. The conductor layer is usually silver or gold palladium, and printed on the ceramic substrate.

The advantage of thick films on ceramic boards is manufacturers can put interchangeable conductors, semi-conductors, conductors, electric capacitors, or resistors on the ceramic board. After completing the steps of printing and high-temperature sintering, all the components on the board can be laser-trimmed to their desired values.

Thin Film Ceramic Boards

The thickness of the conductor layer in thin film ceramic boards is less than 10 microns and deposited on the ceramic substrate using thin film manufacturing technologies such as electroplating, sputtering, or evaporation. The thin films are useful in producing on-board passive networks, assemblies for micro-components, and hybrid integration of circuits formed by packaging.

Depending on the concentration of component parameters and the distribution of the passive networks, thin film ceramic PCBs may be further categorized into lumped or distributed parameters. While lumped parameters cater to frequencies lower than that used for microwaves, the distributed parameters are meant for operating within the microwave band alone. Usually, the equipment used for manufacturing thin film ceramic boards is more expensive than those used for making thick film types. In addition, the cost of production is higher for thin film technology.

Thin film ceramic PCBs are very useful for analog circuits such as for microwave circuits, as they need to exhibit high accuracy, greater stability, and excellent performance.

DCB Ceramic Boards

Direct copper bonded (DCB) technology represents a special process where a copper foil is bonded on to the ceramic core (AIN or AL2O3) on one or both sides. The bonding takes place under high temperature and pressure.

This type of bonding not only gives the super-thin DCB substrate high bonding strength, but it also has excellent isolation, high thermal conductivity, and fine solderability. Showing high current loading capacity, the DCB ceramic board can be etched similar to normal FR4 PCBs are.

Conclusion

At PCB Global, we have the capability not to only provide ceramic PCB’s, but to also assist you with any design specifications or inquiries you may have regarding the general use and outcome of the purpose of your ceramic board and also determining if a ceramic PCB is the right choice for your requirements. For any questions or if you would like to arrange a quote for your ceramic PCB, please don’t hesitate to contact us as sales@pcbglobal.com