Aluminum Printed Circuit Board (PCB)

What is Aluminum PCB?

Aluminum PCB is a type of circuit board made with an aluminum alloy as the substrate, widely used in electronic devices that require efficient heat dissipation, especially in high-power applications like LED lighting. Compared to traditional FR-4 (fiberglass-reinforced epoxy resin) substrates, aluminum PCBs have significant advantages, particularly in heat management and mechanical performance.

Structural Features of Aluminum PCB

The structure of an aluminum PCB typically consists of three layers: the circuit layer (usually made of copper), the thermal insulation layer, and the metal base layer (primarily aluminum). This structure enables the PCB to effectively transfer heat, preventing sensitive electronic components from overheating, and improving the overall performance and lifespan of the device.

• Circuit layer: This is the copper layer, usually copper foil, where electronic components are installed and connected to form the circuit.
• Thermal insulation layer: An insulating layer that separates the circuit layer from the aluminum base. It is designed to have low thermal resistance to facilitate effective heat transfer while preventing electrical conductivity between layers.
• Aluminum base layer: The base layer made of aluminum has excellent thermal conductivity, which is crucial for heat dissipation. The low thermal resistance of aluminum ensures that the heat generated by the electronic components dissipates quickly, preventing component damage and improving reliability.

Circuit Layer

Material: The circuit layer is usually made of copper foil, which is used to create the electrical circuits that connect the components.

Function: This layer acts as the conductor for the electrical signals and provides a pathway for the various components mounted on the PCB, such as resistors, capacitors, diodes, and ICs. The copper is etched to form the required circuit patterns, enabling the proper functioning of the electronic device.

Thermal Insulation Layer

Material: This layer is typically made from an insulating material like epoxy resin, polyimide, or ceramic.

Function: The thermal insulation layer serves as a thermal barrier between the circuit layer and the metal base layer (aluminum). Its primary role is to prevent electrical conductivity between the circuit layer and the aluminum base while allowing efficient heat transfer. It is designed to have low thermal resistance to facilitate heat dissipation from the electronic components.

Key Features: The layer also plays a role in ensuring that heat from the circuit layer can be efficiently transferred to the aluminum base without affecting the electrical integrity of the PCB.

Metal Base Layer (Aluminum)

Material: The metal base layer is typically made from aluminum or sometimes copper or other metals (depending on the specific application and requirements).

Function: The aluminum base layer provides excellent thermal conductivity, allowing the heat generated by the electronic components to be rapidly transferred away from the circuit layer. Aluminum’s low thermal resistance ensures that the heat dissipates quickly, which helps to maintain the temperature of the PCB at safe levels and prevent overheating.

Advantages:

Aluminum is lightweight yet durable, providing both mechanical strength and thermal management.

It helps to increase the reliability and lifespan of the PCB by ensuring that the temperature-sensitive components are kept cool.

In general, considering both cost and technical performance, aluminum PCBs are the preferred choice. Available aluminum materials include 6061, 2052, 1060, etc. If higher requirements are placed on thermal conductivity, mechanical performance, electrical performance, or other specific performance standards, copper, stainless steel, iron, or silicon steel plates can also be used.

Structure Type of Aluminum PCB

• Single-sided Aluminum PCB: In this type, the circuit layer is applied to one side of the aluminum substrate, and the other side is exposed as a heat-dissipating metal base.
• Double-sided Aluminum PCB: In this type, there are circuit layers on both sides of the aluminum substrate, with an insulating layer between the aluminum base and the copper circuits. This design is suitable for more complex circuits and higher-density applications.
• Multi-layer Aluminum PCB: Although less common, this type can be found in some high-end applications. It consists of multiple layers of circuit boards and insulating layers, with the aluminum base providing thermal management for all layers.

Single-Sided Aluminum PCB

Structure: In this configuration, the circuit layer is applied to one side of the aluminum substrate. The other side is exposed as a heat-dissipating metal base, which efficiently channels heat away from the components.

Key Features:

One-sided circuit layout with the aluminum base on the reverse side.

A dielectric layer is placed between the circuit and the aluminum to ensure electrical insulation.

Commonly used in applications with moderate heat generation, like LED lighting, power supplies, and automotive electronics.

Advantages:

Simple and cost-effective for less complex circuit designs.

Effective heat dissipation with the exposed aluminum base.

Used where high thermal conductivity and efficient cooling are needed.

Double-Sided Aluminum PCB

Structure: This type features circuit layers on both sides of the aluminum base. Between the two layers of copper circuitry, there is an insulating dielectric layer, which provides electrical isolation and ensures stability.

Key Features:

The aluminum base serves as the heat sink, while the two copper layers can be used to accommodate more complex or high-density circuits.

A thicker insulating layer separates the two copper circuit layers from the aluminum base.

This structure is suitable for more complicated applications that require more components or circuit complexity, such as power amplifiers, automotive systems, or advanced LED applications.

Advantages:

Allows for higher circuit density.

Improves heat dissipation by utilizing both sides of the aluminum base.

Enhanced thermal performance, ideal for high-power applications where heat management is critical.

Multilayer Aluminum PCB

Structure: A more advanced type of PCB, the multilayer aluminum PCB comprises multiple circuit layers (more than two), sandwiched between insulating dielectric layers. The aluminum base provides thermal management across all layers.

Key Features:

Multiple layers of copper circuitry stacked and separated by insulation, allowing for the creation of highly complex and high-density circuits.

The aluminum base serves as a thermal management system, maintaining efficient heat dissipation across all layers.

Used in high-end applications such as military electronics, aerospace, and advanced industrial equipment.

Advantages:

Can support extremely complex circuits with multiple layers for high-density components.

Enhanced thermal performance by utilizing aluminum as a heat sink for the entire board.

Perfect for applications that require multi-layer circuits with both electrical and thermal management, such as RF amplifiers, high-power LEDs, and high-frequency communication equipment.

In high-end applications, double-sided aluminum PCBs may be used, which have a structure consisting of an upper circuit layer, an insulating layer, an aluminum base, another insulating layer, and a lower circuit layer. Additionally, in rare cases, multilayer aluminum PCBs may be used, which may include standard multilayer boards, insulating layers, and an aluminum base.

Aluminum PCB Advantages

Aluminum PCBs not only have excellent thermal conductivity, durability, and lightweight characteristics, but also offer multiple advantages such as being environmentally friendly, reducing costs, and improving reliability. Their efficient heat dissipation, environmentally friendly properties, and good mechanical durability make them indispensable materials in high-power, high-performance electronic devices. They are widely used in LED lighting, automotive electronics, power modules, communication equipment, and many other fields.

• ROHS Compliant: Aluminum PCBs meet ROHS standards, making them an ideal choice for green and eco-friendly products. This feature ensures compliance with the increasingly strict environmental regulations worldwide.
• Suitable for Surface Mount Technology (SMT): Aluminum PCBs support Surface Mount Technology (SMT), allowing components to be mounted on the circuit board more efficiently and accurately. This technology not only improves production efficiency but also reduces the need for manual soldering, lowering the possibility of human errors.
• Effective Thermal Management: Aluminum PCBs effectively address the heat dissipation problem in circuit design. Due to aluminum's excellent thermal conductivity, it can rapidly transfer the heat generated by the circuit to the external environment, thus effectively reducing the temperature. This minimizes the negative impact of high temperatures on electronic components, preventing overheating that could cause circuit board failure or damage.
• Improved Product Reliability and Service Life: By lowering the operating temperature, aluminum PCBs can improve the power density and overall reliability of electronic devices. As the temperature decreases, the performance of electronic components becomes more stable, reducing losses and failure rates, thus extending the service life of the device.
• Reduced Product Size and Cost: Aluminum PCBs help reduce the overall size of products while ensuring good heat dissipation performance. This not only optimizes product design but also effectively lowers hardware and assembly costs. For products with the same power and functionality, aluminum PCBs are often more compact and cost-effective than PCBs made of other materials.
• Replacing Ceramic PCBs, Enhanced Mechanical Durability: Aluminum PCBs can replace traditional ceramic PCBs, providing better mechanical strength and durability. While ceramic PCBs have good thermal stability, they are relatively brittle and prone to cracking, whereas aluminum PCBs are sturdier, capable of withstanding greater impacts and pressure, reducing the risk of damage during production, transportation, and use.
• Environmental Benefits: Aluminum is a non-toxic, recyclable material that meets environmental requirements. Using aluminum to manufacture PCBs helps save energy since aluminum is easy to process and assemble. Moreover, aluminum's high recyclability reduces production waste, minimizes environmental pollution, and has a smaller ecological footprint.
• Excellent Heat Dissipation Performance: High temperatures are one of the biggest threats to electronic devices, and the thermal conductivity of aluminum PCBs can rapidly transfer heat away from the heat source, protecting key components from overheating. The heat diffusion capability of aluminum ensures that electronic devices will not fail or experience performance degradation due to heat buildup during prolonged operation.
• Higher Durability: Compared to traditional ceramic or fiberglass substrates, aluminum PCBs offer greater strength and durability. Aluminum materials are tough and resilient, effectively preventing damage from collisions or pressure during transport, installation, or use. Aluminum PCBs can also withstand higher operating temperatures, adapting to the needs of harsh environments.
• Lightweight Characteristics: Aluminum PCBs offer significant weight reduction advantages. Compared to traditional materials such as ceramics or steel, aluminum is lighter. Despite its excellent strength and durability, aluminum PCBs are much lighter than other metals, making them suitable for weight-sensitive applications such as portable devices, automotive electronics, and aerospace fields.

Aluminum Printed Circuit Board (PCB) Applications

Audio Equipment

Input and Output Amplifiers: Aluminum PCBs are widely used in audio equipment's input and output amplifiers, primarily because they require efficient heat dissipation to ensure stable operation. The excellent thermal conductivity of aluminum quickly dissipates the heat in the circuit board, preventing overheating and enhancing amplifier performance and lifespan.

Balanced Amplifiers: Balanced amplifiers are used for audio signal processing. Aluminum PCBs help maintain temperature stability, reducing distortion and noise caused by heat accumulation.

Audio Amplifiers, Preamplifiers, Power Amplifiers: These amplifiers generate a significant amount of heat during high-power operation. The excellent heat dissipation properties of aluminum PCBs help high-power audio amplifiers improve efficiency and reduce damage caused by overheating.

Power Equipment

Switch Regulators, DC/AC Converters, SW Regulators: These devices require frequent switching of currents, generating considerable heat during operation. Aluminum PCBs effectively dissipate heat, maintaining device operating temperature and preventing component overheating that would affect power efficiency and stability.

Communication Electronic Devices

High-Frequency Amplifiers: In wireless communications, high-frequency amplifiers are used to enhance signal strength. Since high-frequency signals generate substantial current, aluminum PCBs help these components effectively dissipate heat, ensuring stable operation of high-frequency amplifiers over long periods.

Filter Circuits, Transmitters: These circuits also generate heat during operation. Aluminum PCBs, with their excellent thermal conductivity, rapidly transfer the heat away, preventing the circuits from overheating and ensuring the proper functioning of communication devices.

Office Automation Equipment

Motor Drivers: Motor drivers typically handle high currents and generate significant heat during operation. Aluminum PCBs help dissipate heat from the power section of the motor driver, improving efficiency and lifespan, particularly during prolonged operation.

Automobiles

Electronic Regulators: In cars, electronic regulators (such as electronic control units, ECUs) control engines, gearboxes, and other essential systems. Due to the high working temperatures of these electronic components, aluminum PCBs effectively dissipate heat, ensuring the stability and reliability of automotive electronics.

Igniters: Aluminum PCBs are used in the circuit boards of igniters to help dissipate heat and prevent overheating from affecting the performance of the igniter, ensuring smooth engine ignition.

Power Controllers: Power controllers regulate the power distribution to various electronic devices in a car. Aluminum PCBs, through their thermal conductivity, ensure these controllers operate efficiently and have a long service life.

Computers

CPU Boards: Aluminum PCBs are used as heat sinks in computer CPU boards, helping to efficiently dissipate heat and prevent excessive temperatures from destabilizing or damaging the computer.

Floppy Disk Drives: While floppy disk drives are becoming obsolete, they used aluminum PCBs as thermal management solutions to enhance the stability of hard drives or drives.

Power Units: Computer power units handle high voltage and current, and aluminum PCBs provide effective heat dissipation to ensure the stability and reliability of the power components.

Power

Module Converters: Aluminum PCBs are used in power module converters, helping these converters dissipate heat effectively during voltage conversion, preventing overheating that could cause damage and improving conversion efficiency.

Solid-State Relays: Solid-state relays control the switching of circuits, and aluminum PCBs help dissipate heat, maintaining the device's operation at a stable temperature.

Rectifier Bridges: Rectifier bridges convert AC to DC. They generate significant heat during operation, and aluminum PCBs provide excellent thermal management, preventing components from overheating and improving the rectifier's performance.

Lighting Fixtures

LED Fixtures: With the widespread use of energy-efficient and LED lighting, aluminum PCBs have become a core component of these fixtures. LED fixtures have high brightness and long service life but generate considerable heat. Aluminum PCBs, with their excellent thermal conductivity, effectively transfer the heat from the LED components to the external environment, ensuring that LED fixtures work efficiently and stably, preventing high temperatures from causing reduced light efficiency or failure.

Aluminum PCB material

Aluminum-based PCB (aluminum printed circuit board) materials are mainly divided into 1000 series, 5000 series, and 6000 series, each of which has its unique characteristics and applications.

1000 Series Aluminum: This series includes models such as 1050, 1060, and 1070, commonly known as pure aluminum plates. The 1000 series aluminum has the highest aluminum content, with purity reaching over 99.00%. Since it does not contain other alloying elements, its production process is relatively simple, and therefore, it is more economical, widely used in conventional industries. The majority of aluminum-based PCB materials circulating in the market are from the 1050 and 1060 series.

5000 Series Aluminum: Representative models include 5052, 5005, 5083, and 5A05. The 5000 series aluminum is a common alloy aluminum plate, with the main alloying element being magnesium, typically ranging from 3% to 5%. Therefore, it is also known as aluminum-magnesium alloy. The main advantages of this series include low density, high tensile strength, and good ductility. Compared to other series, aluminum-magnesium alloys are lighter for the same area, which is why they are widely used in aerospace applications (such as aircraft fuel tanks). In addition, the 5000 series aluminum plate has many applications in conventional industries due to its hot-rolled process, which is suitable for anodizing, and it is well established in the domestic market.

6000 Series Aluminum: Represented by the 6061 model, the main alloying elements are magnesium and silicon, combining the advantages of the 4000 and 5000 series. 6061 aluminum is a cold-treated aluminum forging, suitable for applications requiring high corrosion resistance and oxidation resistance. Its excellent interface properties make it easy to coat and process, with very good machinability. Typical applications of 6061 aluminum plate include aircraft components, camera parts, couplers, ship fittings, electronic components, and connectors.

Among the 1000 series, the 1060 aluminum plate is the most commonly used choice for PCB materials due to its superior performance in texture, hardness, ductility, chemical properties, and price.

Aluminum PCB Insulating Layer

The insulating layer of an aluminum-based PCB is one of its core technologies, responsible for bonding, insulation, and heat conduction. As an important thermal barrier in power module structures, the performance of the insulating layer directly impacts the overall thermal management of the system.

The stronger the thermal conductivity of the insulating layer, the more effectively it can dissipate the heat generated during operation, thereby reducing the operating temperature. This not only helps improve the module's power load capacity, reduces the size of the device, but also extends its service life and enhances power output efficiency. Therefore, optimizing the thermal conductivity of the insulating layer is key to ensuring the efficient operation of the aluminum-based PCB.

The withstand voltage of Aluminum PCB

The voltage withstand capability of an aluminum-based board is closely related to the quality of its insulating layer, typically with a withstand voltage of about 500V. However, different application scenarios have different voltage requirements for the aluminum-based board. Some clients may require a withstand voltage of 3500V to 4000V, which is typically achieved by increasing the thickness of the insulating layer.

Steps for aluminum board voltage withstand testing:

• Preparation: Clean the workbench and wear anti-static gloves to ensure a safe and clean testing environment.
• Device Setup: Turn on the voltage tester and set the required test voltage and circuit.
• Connect the Wiring: Before connecting the aluminum-based board to be tested, ensure the voltage meter reads "0" and that the test indicator light is off. Then, connect the ground wire.
• Start the Test: When starting the test, make sure the red probe is facing away from personnel, and press the test button to begin the test.
• Observe the Results: During the test, if the voltage withstand tester does not trigger an alarm and there are no signs of perforation, burning, or discoloration on the aluminum board, the test result is considered qualified; if any of the above issues occur, the test fails.
• End Steps: After the test is completed, be sure to reset the test button and ensure the high voltage input reads "0" before removing the product to ensure safe operation.

Classification of aluminum substrates

• General-purpose aluminum-clad copper boards: This type of aluminum-clad copper board typically has an insulating layer made from epoxy glass fabric, suitable for general electronic component applications.
• High heat dissipation aluminum-clad copper boards: This type of aluminum-clad copper board uses epoxy resin or other resins with a higher thermal conductivity as the insulating layer, specifically designed for applications that require efficient heat dissipation.
• High-frequency circuit aluminum-clad copper boards: Their insulating layer is made from polyolefin resin or polyimide resin bonded with glass fabric, suitable for circuits that transmit high-frequency signals, effectively reducing signal loss.

Compared to traditional FR-4 copper-clad boards, aluminum-clad copper boards have significant advantages in heat dissipation. For example, the thermal resistance of a 1.5mm thick FR-4 copper-clad board is typically between 20 and 22°C, while the thermal resistance of an aluminum-clad copper board is only between 1.0 and 2.0°C, significantly reducing thermal resistance and demonstrating superior heat dissipation capabilities. This makes aluminum-clad copper boards more reliable and efficient in high-power and high-heat applications.

Aluminum core PCB manufacturing capabilities

Technical requirements of aluminum substrate

Dimension Requirements

This includes the overall dimensions of the board and its deviations, thickness requirements and deviations, verticality and warpage requirements, etc.

Board Dimensions and Deviations: The length, width, and thickness of the aluminum baseboard should meet the customer's custom requirements, and the deviations should be within the specified range.

Thickness and Deviations: The thickness of the aluminum baseboard must be precise, with strict tolerance ranges, and the deviation value should not exceed the set limits.

Verticality and Warpage: The surface of the aluminum baseboard should maintain good verticality and minimal warpage to ensure that no deformation occurs during subsequent processing or installation.

Appearance Requirements

The appearance of the aluminum baseboard should be free of obvious defects, common defect types include cracks, scratches, burrs, delamination, and the integrity of the aluminum oxide film.

Cracks: There should be no visible cracks on the surface of the aluminum baseboard, as these cracks may reduce the strength of the board.

Scratches: The aluminum baseboard surface should not have deep scratches, and shallow scratches should be within an acceptable range to avoid affecting electrical performance and appearance.

Burrs and Delamination: The edges of the aluminum baseboard should not have burrs, and the interlayer bonding of the aluminum baseboard should be firm, with no delamination occurring.

Aluminum Oxide Film: The oxide film on the aluminum baseboard should be uniform, of appropriate thickness, and free from peeling or damage, ensuring good corrosion resistance and insulation performance.

Performance Requirements

The performance indicators of the aluminum baseboard include peel strength, surface resistivity, minimum breakdown voltage, dielectric constant, flammability, and thermal resistance, among others.

Peel Strength: The insulating layer of the aluminum baseboard should be firmly bonded to the aluminum base material, and the peel strength should meet the standard requirements, typically tested in N/cm.

Surface Resistivity: The surface resistivity should meet the electrical performance requirements to ensure that the aluminum baseboard will not cause short circuits or other electrical faults during use.

Minimum Breakdown Voltage: The insulating layer of the aluminum baseboard needs to withstand a certain voltage without breaking down, and the minimum breakdown voltage should meet the corresponding standards to ensure the electrical safety of the board.

Dielectric Constant: The dielectric constant is an important indicator affecting signal transmission speed. The dielectric constant of the aluminum baseboard should be within the specified range to ensure circuit stability.

Flammability: The flammability of the aluminum baseboard should meet industry regulations to ensure that it will not catch fire due to overheating in high-temperature environments.

Thermal Resistance: Thermal resistance is an important indicator for evaluating the heat dissipation performance of the aluminum baseboard. The thermal resistance value should be as low as possible to ensure effective heat dissipation during operation, preventing overheating.