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What are the materials of ceramic circuit boards?
From the substrate level, ceramic PCBs include aluminum substrates, AlN substrates, BeO substrates, Si₃N₄ substrates, hybrid substrates, etc. From the number of layers of the circuit board, there are single-layer, double-layer, multi-layer, etc. Here we only list the types of ceramic PCBs according to the different ceramic substrates.
Alumina substrate
Advantages: cheap price, good thermal conductivity, high resistance, high hardness, high electrical insulation, strong corrosion resistance, high biocompatibility
Application: white light, infrared, VCSEL LED lights
Alumina (Al2O₃) PCB, or alumina PCB, is the most commonly used ceramic PCB on the market today because of its cheap price and excellent performance. Alumina has good thermal conductivity and resistance. Therefore, when using alumina PCB, there is no need to add an insulating layer.
Alumina PCBs are mainly used for LEDs with a power of 3W to 5W. Why? Because the thermal conductivity is not very good and cannot meet the requirements of high-power devices.
Alumina has a higher thermal expansion coefficient than semiconductors. Therefore, you cannot expect to use alumina PCBs for large-scale integrated circuits.
But generally speaking, if your device does not have very high power requirements, then alumina PCB is sufficient.
In the alumina PCB market, there are 75%, 96% and 99% alumina PCBs - the higher the purity, the better the performance, but the higher the cost. PCBONLINE uses 96% alumina to make alumina PCBs. Why? Because it is for the balance between quality and manufacturing cost. From the table below, you will find that there is not much difference in performance between 96% and 99% alumina.
Aluminum Nitride PCB
Advantages: higher thermal conductivity and resistance, high hardness, high mechanical strength, higher electrical insulation, strong corrosion resistance, high biocompatibility, thermal expansion coefficient close to Si
Applications: high-power LED, power module, laser field
The thermal conductivity of aluminum nitride PCB or AlN PCB is 7 to 10 times higher than that of alumina PCB. Why is thermal conductivity mentioned first and mentioned many times? Because it is the most important performance for evaluating ceramic PCBs.
Aluminum nitride PCB is considered to be the most promising ceramic PCB in the future. With them, heat can be dissipated immediately from ICs and other expensive components. Therefore, high-power devices such as LED boat lights, truck lights, solar cell modules, large-scale integrated circuits, etc. use AlN PCB as a substrate. Heat does not accumulate in the chip, so the device can work normally for a long time at high current.
Another reason why AlN PCB is popular with high-power LEDs and power modules is its thermal expansion coefficient (4.6×10ˆ-6°C) similar to that of semiconductor Si (3.5~4×10ˆ-6°C). The chips of these high-power devices are made of silicon. Due to the similar thermal expansion coefficient, the chip will not fall off the AlN PCB substrate during thermal deformation.
Silicon Nitride PCB
Advantages: high thermal conductivity, high strength, high fracture toughness
Applications: IGBT modules, vehicle modules, military, aerospace, aviation modules
Unlike brittle traditional ceramic materials, silicon nitride PCB or Si₃N₄PCB has good mechanical strength and fracture toughness at high temperatures. In addition, Si₃N₄ PCBs have high thermal conductivity (80+W/mK). In addition, the thermal expansion coefficient of silicon nitride PCBs matches that of Si.
As you know, IGBT modules for vehicles require higher thermal conductivity than industrial-grade IGBTs. Vehicle modules work in a vibration environment. For safety, automotive materials should also have good impact resistance.
Therefore, vehicle-grade modules all use silicon nitride PCBs. For the same reason, military, aerospace, and aviation modules also use Si₃N₄ PCBs.
However, the manufacturing of silicon nitride PCBs is not so easy. When the circuit layer is sputtered onto the silicon nitride substrate, the bond is not stable. In other words, the circuit layer may fall off the ceramic substrate. Fortunately, PCBONLINE has successful manufacturing experience of silicon nitride PCBs for vehicle-grade IGBT modules.
The last disadvantage of silicon nitride PCBs is that they have lower resistance and insulation than other ceramic PCBs. So keep this in mind when you design your Si₃N₄ PCB project.
Silicon Carbide PCB
Advantages: Good strength even at 1400°C, extremely high thermal conductivity and resistance, good semiconductor conductivity, high hardness
Application: Laser field
Silicon Carbide (SiC) is like diamond, just with a different proportion of carbon. So Silicon Carbide PCB has extremely high thermal resistance. It is easy for SiC PCB to work at 1000°C. That is why they can be used in the laser field.
SiC has the properties of Si, so it has properties close to semiconductors. In other words, unlike other ceramic PCBs, SiC PCBs do not have high insulation.
Currently, the manufacturing cost of SiC PCB is extremely expensive. But in the future, as the manufacturing technology advances, we can expect more applications for Silicon Carbide PCB.
Here is a table of thermal conductivity of different ceramic PCB substrates.
Ceramic circuit board materials face the following challenges in the future:
Technical level
Higher performance requirements: As electronic devices develop towards miniaturization and high performance, ceramic circuit boards need to have higher thermal conductivity, more matching thermal expansion coefficient, better high-frequency performance, etc. For example, 5G communications, automotive electronics, aerospace and other fields have extremely stringent requirements on the stability and reliability of ceramic circuit boards under high frequency, high temperature and high power conditions1.
Difficulties in fine processing: To achieve higher integration and smaller device size, ceramic circuit boards need to be processed more finely. However, ceramic materials have high hardness and brittleness, and are difficult to process. There are technical challenges in achieving high-precision graphics, micro-hole processing, and high aspect ratio structure manufacturing. For example, when preparing thin-film ceramic circuit boards, there are high precision and consistency requirements for circuit design, substrate and film graphics.
Complex process optimization: The preparation process of ceramic circuit boards is complex, such as high-temperature co-firing, direct copper bonding, direct copper electroplating, etc., which require precise control of multiple process parameters, and the connection between different process links is also very demanding. Deviations in any link may affect product quality, so it is necessary to continuously optimize the process to improve the stability and repeatability of the process.
• Cost level
High material cost: High-performance ceramic materials, such as aluminum nitride and silicon nitride, have high preparation costs. At the same time, some metal materials and target materials used in the production process of ceramic circuit boards may also be expensive due to high purity requirements or limited supply, increasing the overall material cost6.
Huge equipment investment: The production of ceramic circuit boards requires advanced equipment, such as high-precision printers, sintering furnaces, sputtering coating equipment, photolithography equipment, etc. These equipment are not only expensive to purchase, but also have considerable maintenance and update costs, which is a large economic burden for enterprises6.
Production efficiency limitations: Complex processes and strict quality control requirements lead to a long production cycle and relatively low production efficiency for ceramic circuit boards. This makes it difficult to reduce the production cost per unit product, and it is difficult to compete with low-cost traditional circuit board materials in market competition.
At a time when the electronics industry is booming, ceramic circuit board materials have become a key support in many fields with their unique advantages. If you have any needs for ceramic circuit board materials, whether it is project development, product upgrades, or simply want to understand the market, you can contact us at any time. We will provide you with accurate quotations and escort your needs with professionalism and enthusiasm.