Heavy Copper PCB
Heavy Copper PCBs Built for Power
2oz to 10oz copper weight for high-current and thermal management applications. Power supplies, inverters, EV battery management, and industrial motor drives.
Key Advantages
Why Choose Heavy Copper PCBs
High Current Capacity
2oz copper at 20mil width carries 3.2A. 4oz at 20mil carries 5.5A. 6oz at 20mil carries 7.8A. Eliminate busbars and reduce connector count by routing power directly through the PCB.
Built-In Thermal Management
Heavy copper acts as a heat spreader, conducting heat away from power components. 4oz copper provides 2x the thermal conductivity path of 1oz copper. Reduce or eliminate external heatsinks.
Extreme Reliability
Thicker copper withstands higher thermal cycling stress and provides better mechanical strength at plated through-holes. Rated for -40°C to +150°C continuous operation in power electronics.
Mixed Signal/Power Layers
Combine heavy copper power layers (4-6oz) with standard signal layers (1oz) in one board. Route power and control on the same PCB, eliminating separate power distribution boards.
Technical Specifications
Heavy Copper PCB Manufacturing Capabilities
Core Parameters
Heavy copper PCBs carry significantly more current than standard 1oz boards while providing built-in thermal management. We support mixed copper weights to combine power distribution and signal routing on a single board.Copper Weight Options
2oz (70μm), 3oz (105μm), 4oz (140μm), 6oz (210μm), 10oz (350μm) custom. Inner and outer layers independently specified. Standard production up to 6oz; 10oz+ requires custom tooling.
Current Capacity (IPC-2221)
2oz external: 10mil=1.8A, 20mil=3.2A, 50mil=7.0A. 4oz external: 10mil=3.1A, 20mil=5.5A, 50mil=12.0A. Internal traces carry approximately 50% less due to reduced convection.
Min Trace/Space per Copper Weight
2oz: 8/8mil. 3oz: 10/10mil. 4oz: 12/12mil. 6oz: 15/15mil. Thicker copper requires wider etching tolerances due to lateral etch undercutting.
Board Thickness Impact
Each ounce of copper adds approximately 35μm per layer. A 4-layer board with 4oz on all layers adds 0.56mm to total thickness. Standard 1.6mm board may need to increase to 2.0mm or 2.4mm.
Mixed Copper Stackups
Different copper weights on different layers: 4oz power planes + 1oz signal layers is a common configuration. Requires careful stackup balancing to prevent warpage during lamination.
Thermal and Power Features
Beyond thick copper traces, heavy copper boards benefit from thermal vias, copper coins, and edge plating to handle extreme power dissipation and high-current interconnects.Thermal Via Arrays
Dense via arrays under power components conduct heat to inner copper planes and the opposite board side. 0.3mm vias on 1.0mm grid provide approximately 4 W/cm² thermal transfer.
Coin/Slug Insertion
Press-fit copper coins (slugs) embedded in the board provide a direct thermal path from component to heatsink. Thermal resistance below 0.5°C/W for high-power IGBTs and MOSFETs.
Power/Signal Layer Isolation
Maintain minimum 15mil clearance between power traces and signal traces. Use dedicated ground planes between power and signal layers. Creepage and clearance per IPC-2221 for working voltages.
Edge Plating for Busbars
Plated board edges act as high-current busbars, connecting top and bottom copper planes. Edge plating carries 2-3x more current than equivalent-width surface traces.
Surface Finishes
HASL, OSP, and ENIG all supported for heavy copper. HASL preferred for power connections (best solderability on large pads). ENIG for mixed signal/power boards with fine-pitch components.
Applications
Where Heavy Copper PCBs Excel
AC/DC converters, DC/DC converters, and switch-mode power supplies where 10-50A currents flow through board-level traces.
Battery management systems (BMS), cell balancing circuits, and battery pack interconnect boards for electric vehicles and energy storage systems.
Variable frequency drives (VFDs), servo motor controllers, and BLDC motor driver boards carrying high-current PWM signals to power stages.
String inverters, micro-inverters, and power optimizer boards handling continuous high-current DC-to-AC conversion in outdoor environments.
On-board chargers (OBC), DC fast charger power modules, and charging pile control boards rated for 50-350A charging currents.
Planar transformer windings, power distribution boards, and busbar replacement PCBs for industrial switchgear and UPS systems.
Design Guidelines
DFM Best Practices for Heavy Copper PCBs
Current Calculation
Follow IPC-2221 standards for trace width sizing. Calculate trace width for your target current with at minimum a 20% safety margin. Always account for ambient temperature — a trace rated for 5A at 25°C may only carry 3.5A at 85°C.
Thermal Relief Design
Use thermal relief pads on power planes to balance thermal dissipation with solderability. Without thermal relief, large copper planes act as heat sinks that make hand soldering impossible and wave soldering unreliable.
Copper Balancing
Maintain equal copper distribution on top and bottom layers to prevent warpage during lamination and reflow. Add copper fills to low-copper layers. For mixed-weight stackups, balance total copper mass symmetrically about the board center.
Trace Width vs Current Tables
Reference IPC-2152 for external and internal layer calculations. Always account for temperature rise — 10°C rise is standard, 20°C for industrial, 30°C maximum. Internal traces carry approximately 50% of external trace current.
FAQ
Common Questions About Heavy Copper PCBs
What is the maximum copper thickness you can manufacture?
Standard production supports up to 6oz (210μm) copper. 10oz (350μm) and above is available as custom production with extended lead times. For extreme current requirements above 10oz, consider copper coin insertion as an alternative to full heavy copper layers.
How much does heavy copper add to board cost?
2oz copper adds approximately 20-30% over standard 1oz boards. 4oz adds 60-80%. 6oz can double the cost or more. The primary cost drivers are extra copper material, longer etching cycles, and tighter process control. Mixed copper stackups (heavy power + standard signal) optimize cost.
Can I mix 1oz signal layers with 4oz power layers?
Yes. Mixed copper weight stackups are common for power electronics. A typical configuration uses 4oz on outer power layers and 1oz on inner signal layers, or vice versa. We verify stackup symmetry to prevent warpage and confirm trace/space minimums for each copper weight.
How do you handle etching on thick copper?
Thick copper requires controlled etching to manage lateral undercutting. At 4oz, expect 12mil minimum trace/space. At 6oz, expect 15mil minimum. We use specialized etch chemistry and extended process times. Trace width compensation is applied to your artwork to account for undercut and deliver finished dimensions on target.
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