It is understood that PCB ceramic substrates have advantages over traditional FR4 PCBs, although ceramic PCBs are relatively new in the list of PCB substrates.But their use in high-density electronic circuits will become more and more popular. Why?In fact, PCB ceramic substrates provide versatility, durability, stability and insulation properties that make them more advantageous than traditional PCBs.Moreover, the PCB ceramic substrate supports circuit miniaturization without compromising accuracy and reliability.The editor will take you to understand the advantages and characteristics of the types of PCB ceramic substrates.For PCBs placed in high pressure or high temperature environments, traditional PCB substrate materials may exhibit defects under extreme conditions.However, PCB ceramic substrate materials are suitable for high temperature and high pressure and corrosive or vibrating circuit conditions, and PCB ceramic substrates have high thermal conductivity and thermal expansion coefficient.These PCBs are best suited for high power density circuit designs used in extreme conditions, especially in the aerospace and automotive industries.PCB ceramic substrates are made from a variety of ceramic materials, and thermal conductivity and coefficient of thermal expansion (CTE) are the two main properties to focus on when selecting ceramic materials.Ceramic materials used in PCBs refer to a class of substrate materials such as aluminum nitride (AIN), aluminum oxide (AI2O3), beryllium oxide (BeO), silicon carbide (SiC), etc. These ceramic materials have similar chemical and physical properties.These we are about to discuss the properties of three common ceramic materials.Alumina ceramics, compared with other alumina ceramic substrates, AI2O3 has advantages in mechanical strength, chemical stability, thermal conductivity and electrical properties.The abundance of raw materials makes alumina the most common ceramic substrate material, AI2O3 ceramic substrate PCBs are used in automotive sensor circuits, shock absorbers and engines.The high thermal stability of AI2O3 ceramic PCBs improves the performance and thermal efficiency of automotive circuits.Aluminum nitride ceramics, its high thermal conductivity and thermal expansion coefficient are two characteristics that make AIN attractive as a substrate material in the PCB industry. The thermal conductivity of AIN varies in the range of 170W/mk to 200W/mk.The CTE of the aluminum nitride ceramic substrate matches that of the silicon semiconductor chip, establishing a good bond between the two, resulting in its assembly reliability.AIN is used in automotive sensor circuits as it can withstand extreme temperatures, corrosion and vibrations while providing an efficient, accurate and sensitive sensor signal.Beryllium oxide ceramic is a kind of PCB ceramic substrate material, its thermal conductivity is about 9 times that of AI2O3, and it is greater than that of metal aluminum.BeO exhibits better chemical stability than AIN and comparable high electrical insulation to AI2O3, BeO is used in applications where PCBs are subjected to high temperatures or high-density PCBs facing space constraints to provide air or liquid cooling.The manufacturing process of the PCB ceramic substrate is simpler than that of the traditional PCB. The thermally conductive ceramic powder and the organic binder are mixed together and heat treated to manufacture the PCB ceramic substrate.Typically, Laser Rapid Activation Metallization (LAM) technology is used for ceramic substrate PCB fabrication.In addition to the ceramic materials used, there is another classification of PCB ceramics according to the manufacturing process:1. High Temperature Co-fired Ceramic (HTCC) - can operate at high temperature without any damage, the construction of HTCC PCB begins with the use of virgin ceramic substrate material, no glass material is added at any stage of manufacture.The manufacturing process of htcc is similar to that of ltcc PCB, the only difference is that the baking temperature of HTCC pcb is about 1600 ~ 1700 ℃ in a gas environment.The high co-firing temperature of HTCC PCBs is so high that the high melting points of metal conductors such as tungsten, molybdenum or manganese are used for circuit traces.3. Direct Bonded Copper (DBC) - The DBC process introduces an appropriate amount of oxygen between the copper and the ceramic before or during the deposition process.The Cu-O eutectic liquid is formed by depositing at about 1065 ℃ ~ 1083 ℃, and the eutectic liquid is chemically reacted with the ceramic matrix to form CuAlO2 or CuAl2O4.The liquid also penetrates the copper foil, forming a combination of copper plate and ceramic substrate.4. Low Temperature Cofired Ceramics (LTCC) - To construct LTCC PCBs, a ceramic material such as alumina is mixed with a glass material in an amount of approximately 30%-50%.For proper bonding, an organic binder is added to the mixture.Spread the mixture on sheets to dry, then drill through holes according to the design of each layer.Typically, screen printing is used to print circuits and fill holes in LTCC PCBs.LTCC PCB fabrication is done by heating in a gaseous oven at 850 ~ 900 °C.