FR-4 VS aluminum plate, Printed circuit boards (PCBs) play a crucial role in modern electronics, serving as the foundation for electronic components. Among the most commonly used PCB materials, FR-4 and aluminum plates stand out due to their unique properties and applications. While FR-4 is widely used for general-purpose electronics due to its excellent insulation and mechanical strength, aluminum plates offer superior thermal conductivity, making them ideal for high-power and heat-sensitive applications.

Understanding the key differences between FR-4 and aluminum PCBs helps engineers and manufacturers choose the right material for their designs, optimizing performance, reliability, and cost.

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1. What is FR-4?

FR-4 is a fiberglass-reinforced epoxy resin material that provides excellent mechanical strength, electrical insulation, and heat resistance. It is one of the most commonly used PCB substrates due to its stability, affordability, and reliability.

Key Characteristics of FR-4:

• Thermal Expansion Coefficient (CTE): FR-4 has a CTE of 50-70 x 10⁻⁶/°C, making it dimensionally stable under temperature fluctuations.
• Electrical Insulation: The material prevents electrical leakage and ensures circuit reliability.
• Mechanical Strength: Its high durability makes it suitable for various applications, from consumer electronics to industrial devices.
• Cost-Effectiveness: Compared to metal-based PCBs, FR-4 is more affordable for standard applications.

However, FR-4 has moderate thermal conductivity, meaning it may not be suitable for applications requiring efficient heat dissipation.

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2. What is an Aluminum Plate PCB?

An aluminum plate PCB, also known as a metal-core PCB (MCPCB), consists of a copper circuit layer, an insulating layer, and an aluminum substrate. This type of PCB is designed for applications that require high thermal performance and excellent heat dissipation.

Key Characteristics of Aluminum Plate PCBs:

• Superior Heat Dissipation: Aluminum conducts heat efficiently, preventing overheating in high-power electronics.
• Electromagnetic Shielding: The metal substrate helps reduce electromagnetic interference (EMI).
• High Mechanical Strength: Aluminum PCBs are tougher and more durable than standard FR-4 boards.
• Lower Thermal Expansion: With a thermal expansion coefficient of 50 x 10⁻⁶/°C, aluminum is more stable under thermal stress than FR-4.

These features make aluminum PCBs ideal for power electronics, LED lighting, and automotive applications, where heat dissipation is critical.

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3. Performance Comparison: FR-4 VS aluminum plate

1. Thermal Management

One of the most significant differences between FR-4 and aluminum PCBs is their thermal conductivity:

• Aluminum’s Thermal Conductivity: Aluminum has a thermal conductivity of 260 W/m·K, which makes it highly efficient at dissipating heat. However, the thermal bottleneck in aluminum PCBs lies in the insulating layer, which has a thermal conductivity of 1-3 W/m·K.

• FR-4 Thermal Conductivity: FR-4 has a much lower thermal conductivity, typically ranging from 0.1-0.3 W/m·K.

Besides thermal conductivity, thickness is also an important factor:

• FR-4 Insulating Thickness: For a 1.0mm board, the insulating thickness is approximately 1.0mm.

• Aluminum Insulating Thickness: For a 1.0mm aluminum PCB, the insulating thickness is only about 0.1mm.

Conclusion: Aluminum PCBs excel in heat dissipation compared to FR-4, especially in high-power applications, offering much better thermal performance.

2. Mechanical Strength and Durability

• Aluminum plates are more rigid and impact-resistant than FR-4, making them ideal for high-stress applications.
• FR-4 PCBs are strong but more prone to warping under extreme conditions.

3. Electrical Performance and Insulation

• FR-4: Provides better electrical insulation, making it suitable for sensitive electronic circuits.

  • For example, for a 1.0mm board thickness, the dielectric breakdown voltage of FR-4 is approximately 12,000V.

• Aluminum PCBs: Require a dielectric layer for electrical isolation, which can impact signal integrity in certain applications. The dielectric breakdown voltage for a 1.0mm aluminum PCB is approximately 4,000V.

4. Thermal Expansion Coefficient (CTE) and Reliability

CTE is a critical factor in PCB performance, as mismatches in expansion rates between materials can cause mechanical failures.

• FR-4 has a CTE of 50-70 x 10⁻⁶/°C, which can cause expansion issues when exposed to high temperatures.
• Aluminum PCBs have a CTE of 50 x 10⁻⁶/°C, which is closer to that of copper (17 x 10⁻⁶/°C), reducing stress on solder joints and vias.

Aluminum PCBs are generally more resistant to thermal expansion issues than FR-4, making them preferable in high-temperature environments.

5. Cost Considerations

• FR-4 PCBs: Are generally cheaper to manufacture and are widely available.

• Aluminum PCBs: Are more expensive due to the additional metal substrate but offer better longevity and performance in high-power applications.

      Cost Comparison:

• Single-Sided 1.6mm PCB: The cost ratio of FR-4 : Aluminum = 1 : 1.

• Double-Sided 1.6mm PCB: The cost ratio of FR-4 : Aluminum = 1 : 4.

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4. Applications of FR-4 and Aluminum Plate PCBs

FR-4 PCBs are commonly used in:

• Consumer electronics (smartphones, computers, gaming consoles)
• Industrial control systems
• Telecommunications and networking devices
• Low-power LED drivers
• Standard automotive circuits

Aluminum Plate PCBs are ideal for:

• High-power LED lighting (streetlights, automotive LED headlights) ESP lots of easy PCB
• Power supplies and converters
• Automotive power modules
• High-frequency and RF applications
• Heat-sensitive industrial electronics

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5. Choosing Between FR-4 and Aluminum Plate PCBs

The choice between FR-4 and aluminum PCBs depends on several factors:

• For standard electronic circuits and cost-sensitive applications, FR-4 is the best option due to its affordability and good electrical insulation.
• For high-power applications that generate a lot of heat, aluminum PCBs provide superior thermal management and mechanical stability.
• For miniaturized, high-frequency circuits, FR-4 offers better signal integrity and easier processing.
• For LED applications and power electronics, aluminum PCBs help prevent heat buildup and extend product lifespan.

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6. Conclusion

Both FR-4 and aluminum plate PCBs serve critical roles in electronics manufacturing, but they cater to different needs. FR-4 is an excellent general-purpose PCB material, offering good electrical insulation, affordability, and stability. Meanwhile, aluminum PCBs excel in heat dissipation, durability, and reliability in high-power applications.

Understanding these differences ensures that manufacturers select the right material for their specific circuit design requirements. Whether prioritizing cost-effectiveness, heat management, or mechanical strength, choosing the correct PCB material is essential for ensuring optimal performance and longevity in electronic devices.

For custom PCB solutions, Shuoqiang Electronics provides high-quality FR-4 and aluminum PCBs tailored to your application needs. Contact us today to discuss your PCB requirements!

Q1: Does the breakdown voltage of FR-4 decrease over time due to aging?
A: Yes, over time, the breakdown voltage of FR-4 can gradually decrease due to prolonged exposure to electrical stress and environmental conditions. Typical aging rates are:

• High-temperature environments (>85°C): Decreases by about 2-3% per year.

• Normal environments: Less than 5% decrease over 10 years.
  Recommendation: For high-voltage designs, reserve at least 20% safety margin for breakdown voltage.

Q2: How can the breakdown voltage of an assembled PCB be tested?
A: Non-destructive testing methods include:

• Step-Voltage Method: Gradually increase the voltage by 500V steps, holding each step for 60 seconds.

• Infrared Thermography: Monitor localized hotspots (early signs of breakdown).

• Partial Discharge (PD) Testing: Identifies potential insulation defects.

Q3: How does the breakdown voltage of FR-4 compare to ceramic substrates (e.g., Al₂O₃)?
A:

Q4: How much does a conformal coating improve breakdown voltage?
A: The breakdown voltage can be improved by applying coatings, depending on the type:

Q5: How do you calculate the breakdown voltage between layers of a multilayer PCB?
A: The breakdown voltage for multilayer PCBs can be calculated using the layered addition formula:

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