Aluminum PCB vs FR4 PCB: Key Differences and How to Choose?

The right type of PCB material can make or break the performance of your electronics project. When engineers and designers plan their PCB projects, they often find themselves deciding between two popular options: Aluminum PCBs vs FR4 PCBs. If you compare aluminum PCB and FR4 PCB, you’ll see that each one is best in different situations. We have worked with both of the materials and will guide you on comparing the differences so you can choose the best one for your needs.

What Is an Aluminum PCB?

An aluminum PCB, a type of metal core PCBs(MCPCB), refers to a board that uses aluminum material as the substrate material, instead of using traditional fiberglass or plastic substrate. It consists of 3 layers: a thermally conductive aluminum base layer, an insulating dielectric layer, and a copper circuit layer. Generally, aluminum PCBs are single-sided, though double-sided versions can also be fabricated. Due to the unique properties of the material, manufacturing mulitlayer aluminum PCBs is difficult and challenging.

Pros and Cons of Aluminum Circuit Boards

Due to its high thermal conductivity, aluminum circuit board can efficiently transfer the heat in high power applications like LED lighting and power supplies. This prevents overheating and extends reliability as well as the lifespan of electronic components. In addition, aluminum PCBs are lightweight yet durable, strong on their mechanical aspect without adding much weight. At the same time, they are very resistant to corrosion and are suitable for harsh environments. However, aluminum circuit boards have their own disadvantages also. Setting up the special equipment to handle the metal base can be expensive. In fact, this can result in an increase in initial cost and lead time of the project. Moreover, the flexibility of aluminum circuit boards is not as good as some other materials, and thus are not suited for designs requiring flexible, or highly compact layout.

What Is an FR4 PCB?

FR4 PCB or Flame Retardant 4 Printed Circuit Board is made from FR4 material, a composite of woven fiberglass cloth impregnated with epoxy resin. This produces an excellent board, which is flame resistant and durable, yet has very good electrical insulation and high mechanical strength. The “4” in FR4 signifies the highest level of flame retardancy hence it is a safe choice for a broad range of electronic applications.

Pros and Cons of FR4 Circuit Boards

FR4 is so versatile that it is good for a multitude of applications from consumer electronics to automotive to telecommunications. Furthermore, it has a relatively low production cost which makes it a popular choice for mass production.

But, FR4 has its own limitations. In high power applications, it can overheat because it has a lower thermal conductivity than aluminum. Its rigidity also makes it inappropriate for the design of flexible circuits. Unlike aluminum, FR4 has good mechanical strength but is more prone to damage from physical stress or environmental factors.

6 Key Differences between Aluminum PCB and FR4 PCB

Let’s dive deep into the Aluminum PCB vs FR4 PCB comparison by examining their key differences:

1. Thermal Management

Aluminum PCBs boast an incredible ability to conduct heat, transferring heat about 600x better than FR4 boards. For heat intensive systems such as LED systems, drive controllers and power management units, aluminum based boards are the preferred choice that offer superior thermal management capability. In contrast, the low thermal conductivity of FR4 boards restricts their use in high -heat situations.

2. Coefficient of Thermal Expansion (CTE)

When PCBs heat up and cool down during use, their materials expand and shrink. FR4 boards have a thermal expansion rate of 12-24 ppm/°C, which is quite different from the copper traces (17 ppm/°C) used on them. This difference can cause the board to break, crack, or have damaged traces. Aluminum boards expand at about 24 ppm/°C, which is closer to copper’s rate, making them less likely to have these problems.

3. Layer Structure

The FR4 technology can accommodate the different layer configurations within a range of single layer to complex multilayer designs. Aluminum boards, however, utilize a specific three-layer structure, which constrains vertical integration options. However, the aluminum based structure is particularly effective at handling high temperatures.

4. Mechanical Strength

The metallic foundation of aluminum PCBs enhances the structural integrity compared with FR4. Enabling larger board sizes and higher component densities, these features make them well suited for applications requiring demanding performance in the telecommunications, industrial automation and vehicle electronics areas.

5. Board Thickness

FR4 boards have layering capabilities that can reasonably vary the board thickness. On the other hand, aluminum PCBs are limited by their three layer structure, usually being around 0.8mm to 4mm in thickness with the metal core being a significant portion of this measurement.

6. Dielectric Properties

With ceramic reinforced polymer, FR4 offers superior electrical isolation properties. FR4 PCBs are featured with low energy loss factor of approximately 0.02 at 1MHz. While for aluminum PCBs. the insulating material used are various, including polyimide or aluminum oxide and they are selected according to the operating frequency requirement.

Considerations When Choosing PCB Materials

When evaluating Aluminum PCB vs FR4 PCB options, consider these crucial factors:

• Power Dissipation: For designs with high power components that generate a lot of heat, aluminum PCBs are the first choices thanks to their excellent thermal conductivity.
• Space Constraints: Aluminium PCBs are used where there is a limitation of space as they are lighter and smaller than FR4 PCB boards.
• Flexibility Requirements: If your design needs flexibility or complex bending, traditional FR4 board may be better as it offers greater flexibility than rigid aluminium PCBs.
• Cost Considerations: Aluminum PCBs cost more than traditional FR4 PCBs; therefore, it is important to assess the cost before making a choice, ensuring it stays within the budget.
• Environmental Factors: FR4’s electrical properties may eventually degrade in high humidity or moisture environments. But Aluminum PCBs have higher resilience to harsh environmental conditions.

Common Applications of Aluminum PCB

• LED lighting systems
• Power supplies and converters
• Automotive electronics
• Industrial control systems
• High-temperature environments
• Applications requiring enhanced durability
• Systems with significant thermal loads

Common Applications of FR4 PCB

• Consumer electronics
• Telecommunications equipment
• Low-power electronics
• Standard multi-layer designs
• Projects requiring cost-effective solutions
• Flexible circuit designs

Final Thoughts

Both Aluminum and FR4 PCBs have their place in modern electronics. While FR4 is still the go-to standard for most applications, aluminum PCBs shine the most in thermal management and high power applications. To make the right choice, understanding the Aluminum PCB vs FR4 PCB comparison is crucial. Then, you need to determine what kind of requirements your application has.

For those seeking expert guidance in PCB selection and manufacturing, MOKO Technology stands out as a leading PCB manufacturer with extensive experience in both FR4 and aluminum PCB production. MOKO Technology has over 20 years of experience providing custom PCB solution and manufacturing services for a range of PCBs, ensuring your product has the best possible performance for your application.