When designing printed circuit boards, copper thickness isn’t just a number – it’s the lifeblood of your board’s performance.
The Copper Thickness Spectrum: From Standard to Heavy
Standard Thicknesses (90% of boards use these):
- 1oz (35μm): The workhorse of the industry
- Used in 70% of consumer electronics
- Handles ~1A per 1mm trace width (outer layer)
- 2oz (70μm): The power player
- Common in automotive and industrial controls
- Carries 2-3x more current than 1oz
Heavy Copper Options (for demanding applications):
- 3oz (105μm): High-current specialists
- Power supplies, motor controllers
- Reduces thermal resistance by 30% vs 1oz
- 4-6oz (140-210μm): Extreme applications
- EV battery management systems
- Industrial power converters
Current carrying capacity calculation formula
Quick calculation method (per IPC-2152):
I = K × (ΔT)^0.44 × (A)^0.75
Hvor?
- I = Current (amps)
- K = 0.048 (outer) or 0.024 (inner)
- ΔT = Temperature rise (°C)
- A = Cross-section (square miles)
Real-world example:
A 2oz, 2mm wide outer trace at 20°C rise:
= 0.048 × (20)^0.44 × (59)^0.75 ≈ 4.5A
Choosing Your Copper Weight: A Decision Matrix
| Applikationsindkapslingsprocesser og møde | Recommended Thickness | Why? |
|---|
| Smartphone PCB | 1oz (35μm) | Cost-effective, space-constrained |
| LED Drivers | 2oz (70μm) | Better heat dissipation |
| ECU'er til biler | 2-3oz (70-105μm) | Vibration resistance |
| Server Power Supplies | 3-4oz (105-140μm) | High current handling |
Consult a professional engineer on how to select copper thickness
Manufacturing process limitations
- 4oz copper requires 50% wider traces than 1oz
- Minimum spacing increases from 0.1mm to 0.3mm
- Indvirkning på omkostninger
- 4oz boards cost 40-60% more than 1oz
- Lead times increase by 2-3 days
- Mixed-thickness designs need symmetrical stacking
- Example 6-layer sandwich:
[1oz – prepreg – 2oz core – prepreg – 1oz]
Pro Tips from Industry Veterans
- Hybrid Designs Save Money
Use thick copper only in power paths (e.g., 3oz) with 1oz for signals
- Impedans-kontrol
For 50Ω lines at 1oz:
- FR4: 1.6mm trace over 0.2mm dielectric
- Rogers 4350: 1.2mm trace over 0.15mm dielectric
- Termisk styring
A 2oz ground plane reduces hot spot temps by 15-20°C vs 1oz
The Future: Thinner and Thicker
Emerging trends show two divergent paths:
- Ultra-thin (12μm): For flexible electronics and 5G mmWave
- Ultra-thick (10oz+): For next-gen power modules in renewable energy systems