2024-10-31
Unlike ordinary PCBs that use adhesives to bond copper foil and substrate together, ceramic PCBs are assembled by bonding copper foil and ceramic substrate together in a high-temperature environment.
The main materials of ceramic substrates
Aluminum oxide (Al2O3) is the most commonly used substrate material in ceramic substrates because it has high strength and chemical stability compared to most other oxide ceramics in terms of mechanical, thermal, and electrical properties. It also has abundant raw material sources and is suitable for various technological manufacturing and different shapes. According to the different percentages of aluminum oxide (Al2O3), it can be divided into 75 ceramics, 96 ceramics, and 99.5 ceramics. The content of alumina varies, and its electrical properties are almost unaffected, but its mechanical properties and thermal conductivity vary greatly. Low purity substrates have more glass and higher surface roughness. The higher the purity of the substrate, the smoother, denser, and lower the dielectric loss, but the higher the price.
Beryllium oxide (BeO) has a higher thermal conductivity than aluminum metal and is used in applications that require high thermal conductivity. When the temperature exceeds 300 ℃, it rapidly decreases, but its toxicity limits its own development.
Aluminum nitride (AlN) is ceramics with aluminum nitride powder as the main crystalline phase. Compared to alumina ceramic substrates, the insulation resistance and insulation withstand voltage are higher, and the dielectric constant is lower. Its thermal conductivity is 7-10 times that of Al2O3, and its coefficient of thermal expansion (CTE) is approximately matched with that of silicon wafers, which is crucial for high-power semiconductor chips. In the production process, the thermal conductivity of AlN is greatly affected by the residual oxygen impurity content. Reducing the oxygen content can significantly improve the thermal conductivity. At present, it is not a problem for the thermal conductivity of the production level to reach 170W/(m · K) or above.
Advantage
Has excellent thermal conductivity and insulation properties
The dielectric constant is very low, the dielectric loss is small, and it has excellent high-frequency performance, which is widely used in the field of high-frequency communication.
Ceramic PCB boards are resistant to high temperatures, corrosion, environmental protection, and can work at high frequencies for a long time in very complex environments, with a long service life
Shortcoming
Fragile is the main drawback, which means that only small area circuit boards can be made;
Expensive price, currently mainly used for high-end products
CONTACT US AT ANY TIME
