Metal Core PCB vs FR4 + Dissipador: Guia para LEDs de Alta Potência

Introduction: The Thermal Challenge

LEDs generate significant heat at the junction—up to 70-80% of input power becomes heat rather than light. Managing this thermal load is critical for LED performance, efficiency, and lifespan.

The classic question: Should you use Metal Core PCB (MCPCB) or standard FR4 with an external heatsink?

The answer depends on power level, cost targets, and reliability requirements. This guide gives you a complete framework for making this decision.

**Hommer's Take**: For high-power LED applications, MCPCB isn't a luxury—it's a necessity. I've seen too many products fail in the field because designers tried to save $0.50 on the PCB and ended up with thermal problems that destroyed LEDs.

Understanding Thermal Conductivity

Material Comparison

What This Means in Practice

MCPCB transfers heat 8-9x faster than standard FR4:

MCPCB Structure Explained

Single-Layer Aluminum MCPCB (Most Common)

A typical LED MCPCB has three layers:

Dielectric Layer: The Critical Factor

The dielectric layer is the thermal bottleneck. Key specifications:

Thinner + higher conductivity = better thermal performance, but higher cost and lower voltage isolation

FR4 with Heatsink: The Alternative

Thermal Via Strategy

For FR4 boards, thermal vias are the primary heat path:

FR4 + Heatsink System Cost

Cost Comparison

PCB Cost Only

Total System Cost Comparison

Scenario: 10W LED module design

Key insight: MCPCB reduces or eliminates heatsink costs, often resulting in lower total system cost for medium-power applications.

Thermal Performance Analysis

Junction Temperature Comparison

For a 3W high-power LED on different substrates:

Impact on LED Life

A 20°C reduction typically doubles LED lifespan

When to Choose MCPCB

✅ Strong candidates for MCPCB:

High-Power Applications

• Individual LED power >1W
• LED module power >5W
• LED density requiring heat spreading
• Outdoor/high-ambient applications

Reliability-Critical

• Automotive lighting (IATF 16949 required)
• Industrial fixtures (10+ year life expectancy)
• Medical lighting equipment
• Aerospace/military applications

Space-Constrained

• Compact designs where heatsink size is limited
• Thin-profile LED panels
• Architectural lighting with minimal visible hardware

Design Advantages

When to Choose FR4 + Heatsink

✅ Better candidates for FR4 approach:

Low-Power Applications

• LED power <0.5W per LED
• Indicator LEDs, signage
• Indoor low-brightness applications
• Battery-powered devices

Cost-Sensitive Products

• Consumer goods with aggressive cost targets
• High-volume, low-margin products
• Disposable or short-lifespan applications

Complex Circuit Requirements

• Multi-layer designs (4+ layers)
• Mixed analog/digital circuits
• High-speed signals requiring impedance control
• Components with different thermal requirements

Prototype/Low Volume

• Early development with uncertain thermal needs
• Low-volume specialty applications
• Quick-turn prototypes using standard materials

Design Guidelines

MCPCB Design Best Practices

Thermal Via Design for FR4

Common Mistakes to Avoid

1. **Underestimating thermal vias needed** — More is better for FR4
2. **Using standard dielectric MCPCB for high-power** — Pay for enhanced dielectric
3. **Ignoring ambient temperature** — Design for worst-case conditions
4. **Poor thermal interface** — TIM selection matters
5. **Inadequate copper spreading** — Use copper pours for heat spreading

Application Selection Guide

LED Power Level Decision Matrix

Application-Specific Recommendations

Real-World Comparison

Case Study: 50W LED Flood Light

Design A: FR4 + External Heatsink

Results: Junction temp 85°C @ 25°C ambient, 4 components, complex assembly

Design B: Aluminum MCPCB

Results: Junction temp 75°C @ 25°C ambient, 2 components, simple assembly

MCPCB saves: $7.70/unit (42%) + better thermal performance

Getting Started

MCPCB Design Checklist

• [ ] Determine total power dissipation
• [ ] Calculate required thermal resistance
• [ ] Select appropriate dielectric (1.0, 1.5, 2.0, or 3.0 W/mK)
• [ ] Specify aluminum thickness (1.0, 1.5, or 2.0mm typical)
• [ ] Design copper layer for heat spreading
• [ ] Add mounting provisions for heatsink if needed
• [ ] Consider white solder mask for reflectivity

Our Aluminum PCB Services

At PCB Portugal, we manufacture:

• **Single-layer aluminum MCPCB** with 1.0-3.0 W/mK dielectric
• **Double-layer MCPCB** for complex LED driver circuits
• **Custom dielectric thickness** for specific thermal requirements
• **Quick-turn prototypes** in 24-48 hours

Explore our Aluminum PCB capabilities or get an instant quote.

Conclusion

The MCPCB vs FR4 + heatsink decision depends on your specific application:

Key takeaways:

1. MCPCB provides 8-9x better thermal transfer than FR4
2. For power levels >1W per LED, MCPCB is typically preferred
3. Total system cost often favors MCPCB despite higher PCB price
4. Every 10°C temperature reduction doubles LED lifespan
5. FR4 with thermal vias can work for low-medium power applications

**Hommer's Take**: The extra $1-2 per board for MCPCB is cheap insurance. I've seen companies spend 10x that amount dealing with field failures from thermal problems. Get the thermal design right the first time.

Need help with your LED thermal design? Contact our engineers for a design review, or calculate your MCPCB cost.

References

1. [FR-4 vs MCPCB for LED Thermal Management](https://www.saturnelectronics.com/press_room/fr-4_vs_mcpcb_for_leds.php) — Saturn Electronics
2. [The Advantages of Metal Core PCBs](https://www.protoexpress.com/blog/advantages-metal-core-printed-circuit-boards/) — Sierra Circuits
3. [Aluminum PCB Guide: MCPCB Thermal Design](https://www.fastturnpcbs.com/blog/aluminum-pcb-guide/) — Fast Turn PCBs