Ceramic PCBs typically consist of ceramic cores, with aluminum oxide and aluminum nitride (AIN) being the two main types. Both types of boards offer better thermal performance than metal-core PCBs because no electrical layer is required between the core and the circuit. Learn more about these two main types of ceramic PCBs below.

AIN: For high thermal conductivity, aluminum nitride sheets are ideal, offering greater than 150 w/mK. AIN is also preferred for many other reasons, such as its good dielectric properties, non-reactivity with various semiconductor process chemicals, and low CTE.
Aluminum Oxide: Due to the high price of aluminum nitride plates, those who choose the less expensive ceramic PCBs may find themselves using aluminum oxide plates. These PCBs are made of aluminum oxide and offer about 18-36 w/mK.

Materials - Aluminum Nitride and Aluminum Oxide
For high thermal conductivity, aluminum nitride boards are ideal, offering greater than 150 w/mK. However, because aluminum nitride boards are expensive, those who choose less expensive ceramic PCBs may find themselves using aluminum oxide boards, which offer about 18-36 w/mK. Both types will provide better thermal performance than metal-core PCBs because no electrical layer is required between the core and the circuit.

Using silver for the printed traces - protected with a glass overlay - will further increase the thermal conductivity (406 W/mK). Other ceramic material options include boron nitride, beryllium oxide, and silicon carbide. Due to the high operating temperatures, ceramic plates are not treated with OSP, HASL or other conventional surface treatments. However, if silver corrosion may be an issue, such as in high sulfur environments, you can use gold-plated ceramic printed circuit boards to protect the exposed pads.

Other Ceramic PCB Material Options
Using silver for the printed traces - protected with a glass overlay - will further increase the thermal conductivity (406 W/mK). Other ceramic material options include boron nitride, beryllium oxide, and silicon carbide.

OSP, HASL, and lead-free HASL finishes are not usually used for ceramic boards in pcba production due to the high operating temperatures. However, if silver corrosion may become a problem (e.g. in high sulfur environments), you can obtain ceramic PCBs with ENIG (Electroless Nickel Immersion Gold) or ENEPIG (Electroless Nickel Palladium Immersion Gold) finishes to protect the exposed pads.