Aluminum PCB vs FR4: When to Use Metal Core

Published June 2026 · 7 min read · By Mayio PCB Engineering

If you're designing power electronics, LED lighting, or anything that generates serious heat, you've probably wondered: should I use an aluminum PCB or stick with FR4? The answer isn't always obvious — and the wrong choice can mean thermal failure or unnecessary cost.

What Is an Aluminum PCB?

An aluminum PCB (also called metal core PCB or MCPCB) replaces the standard FR4 dielectric core with a thin thermally conductive dielectric layer bonded to an aluminum base plate. The aluminum acts as a heat spreader, pulling thermal energy away from components and dissipating it across the board's surface.

The structure looks like this: copper traces on top, a thin dielectric layer (typically 75-150μm), and then the aluminum base (0.5-3mm). Some designs use copper cores instead of aluminum for even higher thermal performance, but aluminum is the standard for cost-sensitive applications.

Thermal Performance: The Numbers

Property	FR4	Aluminum PCB
Thermal conductivity	0.3-0.5 W/mK	1.0-3.0 W/mK (dielectric)
Aluminum base conductivity	N/A	~200 W/mK
Max operating temp	130-140°C	150°C+ (depends on dielectric)
Thermal resistance (typical)	20-40 °C/W	0.5-3 °C/W

The difference is dramatic. A 1W LED running on FR4 might hit 85°C junction temperature. The same LED on aluminum drops to 45°C. That's the difference between a 50,000-hour lifespan and early failure.

When Aluminum PCBs Make Sense

Cost Comparison

Spec (100×100mm, 1.6mm)	FR4	Aluminum PCB
5 pcs prototype	$2	$8-12
50 pcs	$12	$30-45
500 pcs	$80	$150-220
1000 pcs	$140	$250-380

The gap narrows at volume. At 1000+ units, aluminum is often only 2x the cost of FR4 — and the thermal benefit can eliminate the need for heatsinks, fans, or thermal pads, which often costs more than the board itself.

Manufacturing Considerations

Design Rules

• Minimum trace width: 0.15mm (same as FR4)
• Minimum drill: 0.3mm (slightly larger than FR4 due to aluminum base)
• Vias: Standard through-hole vias work, but note the aluminum base must be isolated
• Copper weight: Typically 1oz (35μm), can go up to 3oz for high-current

What You Can't Do

• No buried/blind vias — Aluminum base makes sequential lamination impractical
• Limited to 1-2 copper layers — More than 2 layers is rare and expensive
• No plated through-hole on aluminum side — Requires special isolation processing
• Impedance control is tricky — The thin dielectric changes characteristic impedance calculations

Real-World Example: LED Panel Driver

We recently helped a customer redesign their LED panel driver from FR4 to aluminum. The board had 24 high-power LEDs (0.5W each) plus a constant-current driver IC.

On FR4: LEDs ran at 85°C junction temperature, driver IC hit 95°C. Board needed a separate aluminum heatsink plate + thermal pads. Total assembly cost: $4.20/unit.

On aluminum PCB: LEDs ran at 42°C, driver IC at 55°C. No heatsink needed. Total assembly cost: $3.10/unit.

The aluminum board cost $2 more per unit. The eliminated heatsink saved $3.30. Net savings: $1.30/unit — and a simpler, more reliable product.

Common Mistakes

• Using aluminum for everything — If your board doesn't have a thermal problem, aluminum adds cost with no benefit.
• Ignoring the dielectric layer thickness — Thinner dielectric = better thermal transfer, but lower breakdown voltage. 75μm is typical for low-voltage; 150μm for mains-connected designs.
• Forgetting about weight — Aluminum boards are significantly heavier. Matters in aerospace and wearable applications.
• Designing like it's FR4 — You need to think about thermal paths the way you'd think about signal integrity on FR4. Route heat-generating components over the aluminum base, not over cutouts.