Alumina is a ceramic material renowned for its thermal conductivity, electrical insulation, and high strength. Of all the types of PCBs available, Alumina PCBs are rather special due to their characteristics and uses. In this blog, Fulltronics will cover Alumina PCBs’ definition, types, applications, advantages, and disadvantages.
What is Alumina PCB?
Alumina PCB (Alumina printed circuit board), or Aluminum Oxide Substrate, is a type of ceramic PCB made from Aluminum Oxide (Al2O3) ceramic material. Unlike traditional FR-4 laminates, alumina PCB leverages the unique properties of aluminum oxide, which include:
High Thermal Conductivity
Electrical Insulation
Mechanical Strength
Types of Alumina PCB Substrate
The types of Alumina PCB are categorized by the purity of Alumina in the substrate. There are three types of Alumina PCB substrate:
96% Alumina PCB Substrate
96% alumina printed circuit board substrates are highly regarded in the PCB industry for their excellent balance of cost, availability, and quality standards. These substrates are commonly used in microelectronics, particularly in hybrid microelectronic circuit manufacturing.
The thick film substrate format, often required for these applications, benefits significantly from 96% alumina. Its cost-effectiveness and efficiency make it an ideal choice as a foundational material for hybrid devices.
99.5% Alumina PCB Substrate
The 99.5% Alumina PCB substrate is ideal for applications where grain size is not critical and high-performance specifications are less demanding. It excels in achieving a smooth surface finish of up to 2 micro inches, making it advantageous for certain uses. Although it offers lower flexural strength, thermal conductivity, and dielectric stability compared to higher purity options, it remains a viable choice for many applications.
One of its key benefits is the availability of larger sizes and greater thicknesses, providing versatility for various uses. This substrate is particularly valuable in electronic applications that do not require extremely high purity but still demand consistent performance.
99.6% Alumina PCB Substrate
The 99.6% alumina PCB is a high-purity, fine-grain substrate ideal for high-end applications. It excels in uniform thin film processes such as sputtering, evaporation, and chemical vapor deposition. With a surface roughness below 1 microinch, it significantly reduces defects and enhances smoothness.
This substrate's glass surface is exceptionally defect-free, offering superior mechanical strength, electrical resistivity, and dielectric constant. Additionally, it boasts excellent corrosion resistance and is highly wear-resistant. These properties make the 99.6% alumina substrate the optimal choice for high-reliability and high-accuracy electronic applications.
|
Characteristics |
96% Alumina |
99% Alumina |
|---|---|---|
|
Color |
White |
Beige |
|
Hardness |
1500HV |
1700HV |
|
Density |
3.6g/cm³ |
3.9g/cm³ |
|
Warpage |
≤0.3mm |
≤0.2mm |
|
Parallelism |
±0.4% |
±0.3% |
|
Water Absorption |
0% |
0% |
|
Thermal Conductivity |
25W/(m·K) |
31.4W/(m·K) |
|
Dielectric Constant [1MHz, 25°C] |
9.4 |
10 |
|
Bending Resistance |
3000Kgf/cm² |
3500Kgf/cm² |
|
Surface Roughness Ra |
0.6-0.8μm |
0.6-0.8μm |
|
Voltage Resistance |
18KV |
18KV |
|
Fracture Toughness |
3-4Mpa m1/2 |
4Mpa m1/2 |
|
Sintering Temperature |
1689°C |
1700°C |
|
Thermal Shock Resistance |
200T°C |
220T°C |
|
Maximum Temperature |
1400°C |
1600°C |
|
Thermal Expansion Coefficient [20°C to 300°C] |
6-7.5×10ˆ(-6)°C |
8-10×10ˆ(-6)°C |
What are the Advantages of Alumina PCB?
Alumina is incorporated into PCBs since it possesses good thermal conductivity, hence it serves well in power PCBs and high-temperature PCBs.
Dimensional Stability
Chemical Stability
High Thermal Conductivity
Good Electrical Insulation
High Mechanical Strength
- Thermal conductivity
One of the most remarkable features of Alumina PCBs is their high thermal conductivity. This property allows heat to escape and is very important in high-power electronic circuits. Good thermal management avoids high temperatures and reduces the impact on electronic components, thus increasing their reliability.
- Electrical Insulation
Alumina is also characterized by the fact that it is an electrical insulator. It makes the printed circuit board capable of restraining electric current that is undesirable in the functioning of the PCB. This characteristic is critical when used to ensure the maintenance of circuits in electronic equipment, especially those using high-frequency signals.
- Mechanical Strength
Alumina PCBs are strong and long-lasting. The ceramic material used in these PCBs offers high mechanical strength, and thus these PCBs would not easily bend or vibrate. This makes them appropriate for use in areas of high mechanical stress.
- Chemical Stability
Alumina also offers chemical corrosion resistance, which means that the PCB will be functional in chemically corrosive environments. This is especially the case in industries and automobiles, where workers are susceptible to contact with several chemicals.
- Dimensional Stability
Products with Alumina PCBs have better shape and dimensional stability over a wide temperature range, which is important for product performance under varying thermal conditions. This stability also aids in the precise positioning of electronic components in the working assembly.
What are the Disadvantages of Alumina PCB?
Although aluminum oxide PCB has many advantages, it also performs poorly in some aspects.
Higher Expense
Lower Availability
Manufacturing Complexity
Limited Design Flexibility
Susceptibility to Cracking
-
Higher Cost
Alumina PCBs are generally more expensive to produce than traditional FR-4 PCBs. The increased material and processing costs can significantly impact project budgets, especially for high-volume PCB assembly.
- Manufacturing Complexity
The manufacturing of alumina PCBs involves specialized techniques that can be more complex than those used for standard PCBs. This complexity can lead to longer production times and the need for more specialized equipment.
- Design Flexibility
Once an alumina PCB design is established, making changes can be difficult and costly. This lack of flexibility can hinder rapid prototyping and adaptation to new design requirements.
- Brittleness
While alumina offers strong mechanical properties, it is also brittle. This brittleness makes alumina PCBs prone to cracking or breaking under mechanical stress or impact, which can lead to reliability issues.
- Lower Availability
Alumina PCBs may not be as readily available as traditional PCB materials. Limited suppliers and longer lead times can complicate sourcing, especially in urgent situations.
Applications of Alumina PCBs
Alumina PCBs that are made from Alumina Oxide are central in many vigorous sectors given their superior characteristics. These circuit boards are built to be thermal resistant and have enhanced thermal capacities, thus they can be used in many specific segments.
- High-Power Electronic Semiconductor Modules
Alumina PCBs are important in high-power applications in the semiconductor module because heat dissipation is a major factor and reliability at high temperatures is important. Due to their properties, they ensure that the stability and utilization of these, highly-powered machines, are not affected in any way.
- Anti-Lock Braking Systems (ABS)
This type of PCB used in the car industry functioning as anti-lock brakes requires alumina. These PCBs afford the requisite dependable and thermal properties imperative for system efficiency and security.
- High-Power LED Chips
High power LED applications, Alumina PCB is the most popular one. Their superb heat dissipation design can avoid the issue of chips being burned, thereby improving the life span and efficiency of LED chips.
- Solar Cells
In the case of solar cells, Alumina PCBs are used mainly due to their suitable thermal conductivity and resistance to heat. They assist in controlling heat created on the solar cells to increase efficiency and durability.
- Telecom Devices
In telecommunication, the Alumina PCBs are used in applications that necessitate high reliability and reduce thermal management. This means their applicability for this demanding industry, as they can work at high frequencies and last longer than others.
- Lightweight Industries
Nonetheless, aluminum oxide printed circuit boards are suitable for the production of miniature circuits, such as those used in lighting equipment and sensors, because of their characteristics. They meet the technical needs of small-scale industries and improve production with low-cost solutions.
Many components of an aerospace device work at higher temperatures, and thus, Alumina PCBs for these units are suitable. Owing to such characteristics as high heat dissipation and effective shield, they are used in engines, modules of LEDs, and other aerospace products.
-
Automobile Industries
In the automotive industry, especially in the manufacture of cars, sensors, and other automobiles, important components must be able to perform optimally, and even more must be shielded. This is achieved by the Alumina PCBs, which therefore makes them a steady and dependable material for automotive use. It is quite characteristic of them to be reliable and stable; this makes them vital for the industry.
Across aerospace, telecommunication, automobile, consumer display, and many other applications, Alumina PCB increases performance as well as stability. Thus, Alumina PCBs will continue to play an important role in benefiting from advancements in technology and demand for supporting multiple high-performance applications.
Conclusions
Alumina PCBs are indispensable to different industries because of their super-thermal conductivity, high mechanical stability, and great reliability. Because of their capacity to work under high conditions, they are the most demanded product in high-tech and high-pressed applications.
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