Aluminum nitride PCB is a type of ceramic PCB that uses AlN as its substrate. Compared with alumina PCBs, AlN PCBs have higher thermal conductivity and better properties. Aluminum nitride PCBs have these characteristics:
- 1. High thermal conductivity (170-320W/mK), which is close to that of BeO PCB and SiC PCB, and 7-10 times of alumina PCB.
- 2. Its thermal expansion coefficient (4.6×10ˆ-6°C) is close to that of Si (3.5~4×10ˆ-6°C) and GaAs (6×10ˆ-6°C)
- 3. Good electrical properties (dielectric constant, Dielectric loss, volume resistance, and dielectric strength)
- 4. Good mechanical properties. It has fracture toughness higher than Al₂O₃ and BeO and can be sintered in a normal atmosphere.
- 5. It has good light transfer properties.
- 6. AlN substrate is non-toxic and environmentally friendly.
Due to the above properties, aluminum nitride PCBs have more and more applications. Below are some applications of AlN PCBs.
# 1: IGBT module
In high-power semiconductors, VCSEL chips and IGBT modules have extremely high requirements for thermal dissipation. The IGBT usually has the trench gate structure, whose process precision is 1μm. Compared with the plane grid structure, it has a larger surface and can accommodate more precision components. However, the higher component density leads to greater thermal when the IGBT module works.
Due to this, the aluminum nitride PCB is a good circuit board option for the IGBT module. An AlN PCB has thermal conductivity from 170W/mK to 320W/mK, and its thermal expansion coefficient is close to semiconductors (Si). Besides satisfying the thermal dissipation requirements, the AlN PCB reduces the risk of desoldering for IGBT modules.
# 2: VCSEL module
A VCSEL chip has an extremely high power density, and the power density of every square centimeter reaches several hundred or even more than a thousand Watts. For such a high power density causes, thermal dissipation is a huge problem, and the VCSEL chip and the substrate may have stress issues due to thermal expansion. In such a case, the AlN PCB is used for the VCSEL module.
Aluminum nitride PCB's excellent thermal conductivity and similar thermal coefficient with semiconductors solve the thermal problems perfectly. Besides, AlN PCBs also protect the VCSEL chip from corrosion and maintain its precision.
In some automotive applications, VCSEL modules work in aggressive environments such as strong acids and alkalis. And the VCSEL chips used for smart automotive applications have extreme precision. So the chips have to adopt the vacuum package to keep it from the external environment. To solve the vacuum package needs, three-dimensional aluminum nitride substrate printed circuit boards are used. PCBONLINE adopts the DPC technology to make the substrate board a three-dimensional chamber shape and place the lens above the chip. In this way, the VCSEL chip is protected securely.
# 3: CPV (focused photovoltaic) solar power supply module
CPV is a new solar power supply, and its energy transfer rate reaches 44.5%, about two times higher than that of the Si solar power supply. It uses the condenser to focus the solar light on a chip in the size of about one square centimeter, and the chip transfers the solar energy to electrical energy. But this generates a lot of heat. Its great demand for thermal dissipation leads to the use of aluminum nitride PCBs.
An AlN PCB not only solves the thermal dissipation problem for the CPV solar power supply module. It also prevents its circuit from desoldering due to the close thermal expansion coefficients of AlN and semiconductors.
# 4: High-power LED lighting
Aluminum nitride PCBs are ideal circuit boards for high-power LED lighting products, such as photography light, ship lighting, and so on.
LEDs have inconspicuous temperature rise when the electrical current is small. But when the current is large, there is a drastic temperature increase. The elevating temperatures for long hours can drop the LED composite efficiency and reduce the lighting strength.
So high-power LEDs have to dissipate the thermal as quickly as possible to resist the temperature elevation. AlN PCBs are used for this purpose for ALN is one of the few materials having both good thermal conductivity and electrical insulation.
Besides, the bandgap width of the aluminum ceramic substrate is 6.2eV, and its good insulation makes no need for insulation treatment of high-power packages.
Competitiveness of PCBONLINE in Aluminum Nitride PCB Manufacturing
PCBONLINE adopts DPC technology to manufacture aluminum nitride PCBs. Copper and aluminum nitride substrates are bonded by magnetron sputtering, and the ceramic circuit board has good metal crystallization properties and flatness. The circuit board has stable and reliable properties and improves the bonding strength of the chip and the substrate effectively.
Besides the high quality and three-dimensional circuit capability, PCBONLINE also has these technical strengths in aluminum PCB manufacturing:
- PCBONLINE has a high-density process capability - the minimum line/spacing (L/S) reaches 20μm to realize the small volume, light, and thinness of the products.
- PCBONLINE's AlN PCBs have better welding performance and more high-temperature resistance. The thickness of the conductive layer is arbitrarily customized between 1μm-1mm.
- The AlN PCB's copper layer does not contain an oxide layer and has a long shelf time in aggressive environments.
- The AlN PCBs have a metal layer with lower resistance and stronger adhesion.
PCBONLINE provides free one-on-one engineering support (DFX) to ceramic PCB projects. All levels of production are accepted and manufactured to the same high quality. Besides, PCBONLINE assembles PCBs to IPC-A-610 Class 3 standards.
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Conclusion
This article introduces the characteristics of aluminum PCBs and some of their applications. AlN PCBs are an appropriate circuit board option for semiconductor modules (such as IGBT and VCSEL), solar power supply modules (such as CPV), high-power LED lighting products (such as photography lights and ship lights), etc. This article also introduces a leading aluminum nitride PCB manufacturer, PCBONLINE, for engineers/companies/institutes who are looking for high-quality AlN PCBs.
