PCB Thermal Conductivity Performance: Ceramic PCB Vs Metal Core PCB
When you are looking for substrates for electronic circuits with a high thermal conductivity and a low expansion coefficient (CTE), ceramic PCB will be your preferred choice of material. Today ceramics are already widely used as substrates in many microelectronic components and power LED packages and more and more they are replacing entire printed circuit boards reducing complexity in design and manufacturing while increasing performance. Examples are Chip-on-board (COB) modules, High power circuits, proximity sensors, battery drivers for EVs, … .
Ceramics advantages over other printed circuit boards:
Higher operating temperature up to 350ºC
Lower expansion coefficient
Good thermal properties
Superior high frequency performance
Lower system cost: reduces test, insertion, assembly
Smaller package size due to integration
Cost effective for dense package due to parallel processing of layers
Hermetic packages possible, 0% water absorption
RayMing specializes in Alumina Oxide (Al2O3) and Aluminium Nitride boards (AlN) using thick film as well as direct bonded copper (DBC) and direct plated copper Technologies (DPC) to print the circuits.
Alumina (Al2O3) is widely used because of its low cost. It is, however, a less good thermal conductor (24-28 W/mK) but still outperforms most IMS (metal core) PCB since it does not require a dielectric layer between circuits and core. If needed, thermal performance can be still enhanced using silver (Ag) filled vias. Boards are usually thicker (0.5mm-1.5mm). AluminumOxide can also be made transparent, click here for more info on transparent PCB.
Aluminum Nitride (AlN) has far better thermal performance (>170 W/mK) but is also more expensive. Also here thermal performance can be further improved by Ag or Au traces and vias.
Circuits can either be printed using Copper (Cu) or Silver (Ag) depending on the application and the request. Copper is offered both in DBC/DPC as well as Thick film screen print processes while silver can only be done in using the second manufacturing option. We advise copper in 1-2 layer applications from low to high volume applications. Silver is advised when going to multi-layer and only in medium to high volume due to the higher tooling costs. In case you are unsure what material to specify, please to not hesitate to contact us.
Solder resist and surface finishes can be applied similarly to regular PCB when copper metallization is used. However, for silver thick film designs, we offer only a glass solder mask which is recommended for high-temperature designs. For high sulfur environments where silver corrosion can be an issue, we offer Gold plating as a solution to protect the exposed pads.
Thanks to its dielectric and thermal conductive characteristics, components can be placed directly on ceramic boards allowing heat to flow through easier compared to FR4 and metal core boards. Furthermore, since (buried) vias are possible, multilayer boards can also be made making ceramic PCBs a true alternative for FR4/CEM3 and metal core PCBs.
For a full comparison with FR4/CEM3 and metal core boards, we refer to the table below.