Keywords: Ceramic Substrate,  Ceramic PCB

Several professionals believe Ceramic Substrate, Ceramic PCB to be superior to conventional FR4 PCBs. Although being relatively new on the list of PCB substrates, ceramic PCBs are becoming more and more popular for usage in high-density electronic circuits. Why? Ceramic PCBs are superior to conventional PCBs because of their adaptability, toughness, stability, and insulating qualities. Moreover, ceramic PCBs enable circuit downsizing without sacrificing accuracy and dependability. We'll talk about the many kinds of ceramic PCBs in this post and discover why they're so useful.

Ceramic PCBs

Traditional PCB substrate materials may show defects for Boards put in high pressure or high temperature situations. Nevertheless, high temperature, pressure, corrosive, or vibratory circuit conditions may all be handled by ceramic PCB substrate materials. Both the thermal conductivity and coefficient of thermal expansion of ceramic Boards are high. High power density circuit designs that are employed in harsh environments, particularly in the aerospace and automotive sectors, are best suited for these Boards.

Ceramic PCBs are made from a variety of ceramic materials.When choosing ceramic materials, the two major characteristics to pay attention to are thermal conductivity and coefficient of thermal expansion (CTE). Aluminum nitride (AlN), alumina (Al2O3), beryllium oxide (BeO), silicon carbide (SiC), and boron nitride are examples of the substrate materials that fall within the category of ceramic materials utilized in PCBs (BN). Similar chemical and physical characteristics are present in these ceramic materials. We shall examine the characteristics of three popular ceramic materials below.

Common Ceramic Substrate Materials' Characteristics

The following are the top three ceramic materials utilized in the production of PCBs:

Al2O3 alumina - Al2O3 is superior than other oxide ceramics in terms of mechanical strength, chemical stability, thermal conductivity, and electrical characteristics. Alumina is the most widely utilized ceramic substrate material due to the quantity of raw materials. Automotive sensor circuits, shock absorbers, and engines all employ Al2O3 ceramic Boards. The performance and thermal efficiency of the circuits used in vehicles are enhanced by the great thermal stability of Al2O3 ceramic Boards.

Aluminum Nitride (AlN) – AlN is notable as a substrate material in the PCB sector due to its high thermal conductivity and coefficient of expansion. AlN has a thermal conductivity that ranges from 170 W/mK to 220 W/mK. Because silicon semiconductor chips and AlN ceramic have compatible CTEs, the two may be reliably bonded during assembly. Since AIN can survive severe vibration , corrosion, and temperatures while still producing effective, precise, and sensitive sensor signals, it is employed in sensor circuits in vehicles.

Beryllium Oxide (BeO) is a ceramic PCB substrate material with a thermal conductivity that is better than metal aluminum and approximately nine times that of Al2O3. BeO exhibits higher electrical isolation equal to Al2O3e and greater chemical stability than AlN.BeO is utilized to provide air or liquid cooling in situations where the PCB is exposed to high temperatures or in high-density Boards with space constraints.

Ceramic PCB Types Depending on Manufacturing Processes

Ceramic Substrate, Ceramic PCB are easier to manufacture than conventional PCBs. In order to create ceramic PCBs, a thermally conductive ceramic powder and an organic glue are combined. For the production of ceramic PCBs, laser rapid activation metallization (LAM) technology is typically used. There is another categorization for ceramic PCBs depending on the manufacturing technique in addition to the type of ceramic material used:

A powerful laser is utilized in the LAM (Laser Activation Metallization) PCB process to ionize both metal and ceramic materials. Together, they grow, which forges a close tie between them.

Low-Temperature Co-Fired Ceramic (LTCC) PCB - To make LTCC PCBs, alumina, a kind of ceramic material, is combined with glass in amounts ranging from 30% to 50%. Organic binders are included in the mixture to properly bond the materials. When the mixture has been spread out on sheets to dry, through-holes are drilled in the mixture in accordance with the layout of each layer. LTCC PCBs often employ screen printing to print the circuit and fill the holes. Finishing the LTCC PCB manufacture involves heating it in a gaseous oven between 850 and 900 °C.

HTCC PCBs are designed to function at high temperatures without suffering any harm. They are built of high-temperature co-fired ceramic. The creation of HTCC PCBs begins with the use of a raw ceramic substrate; glass is not added at any point throughout the manufacturing process. The sole distinction between the HTCC and LTCC production processes is that HTCC PCBs are baked at a temperature of around 1600–1700 °C in a gaseous atmosphere. Circuit traces consisting of metals with high melting points, such as tungsten, molybdenum, or manganese, are used because HTCC PCBs have such high co-firing temperatures.

Direct Bonded Copper (DBC) PCB - Before or during the deposition process, a suitable quantity of oxygen is introduced between copper and ceramic in the DBC method. At a temperature of around 1065 °C to 1083 °C, the deposition produces Cu-O eutectic liquid, which is then made to chemically react with the ceramic substrate to produce CuAlO2 or CuAl2O4. Moreover, the liquid permeates the copper foil, creating a substrate that combines copper plate and ceramics.

Direct Plate Copper (DPC) PCB - The PVD technique and sputtering are used throughout the production process of DPC to attach copper to substrates at high temperatures and pressures.

High-temperature, high-pressure, high-frequency, and excellent insulation performance are all well-suited to ceramic PCBs. A PCB Manufacturer offers a wide range of design, simulation, and analysis technologies that may help designers create PCBs out of any material, including ceramic.

Metal cores are typically used in ceramic PCB construction. Aluminum nitride boards are the best choice for high thermal conductivity since they offer more than 150 w/mK. Due to the high cost of aluminum nitride boards, those choosing less costly Ceramic Substrate, Ceramic PCB may end up with aluminum oxide boards, which provide between 18 and 36 w/mK. As there is no need for an electric layer to separate the core from the circuits, both kinds will perform better thermally than printed circuit boards with metal cores.

The printing traces made of silver and protected with glass will have even higher heat conductivity. Beryllium oxide, silicon carbide, and boron nitride are further ceramic material choices. Due to the high operating temperatures, ceramic boards are not coated with OSP, HASL, or other conventional surface treatments. To safeguard the exposed pads, you might acquire your ceramic printed circuit boards with gold plating if silver corrosion might be an issue, as might be the case in situations with high sulfur levels.