Aluminum Thick Copper PCB for Power Supply

Turn your high-power design into reality with San Francisco Circuits - the powerhouse manufacturing/assembly partner behind your heavy copper PCB designs and high-power applications.

We specialize in delivering robust, high-performance heavy copper PCBs fast. Whether your design requires 4 oz or 10 oz copper builds, our network of advanced fabrication partners can meet your toughest electrical and thermal demands.

Engineers choose San Francisco Circuits for our deep technical expertise, fast turnaround times, and proven ability to deliver complex, high-current boards with unmatched reliability. Our heavy copper solutions are ideal for demanding environments, including mission-critical applications in defense, aerospace, and industrial power systems.

From quick-turn prototypes to full-scale production runs, our team ensures your heavy copper boards are built to perform.

Heavy Copper PCB Lead Times

We can turn your heavy copper PCB manufacturing order in as little as 72 hours.

• 72 hours

Bareboard Heavy Copper Fabrication

• 1 - 5 days

Fab + Assembly (full + partial turnkey)

Our Capabilities

Call us at 800.SFC.5143 or get an instant PCB quote.

Heavy Copper PCBs

What are Heavy Copper PCBs?

Heavy copper PCBs are generally defined as printed circuit boards that utilize copper weights of at least 3 oz/ft² per layer, significantly more than standard PCB copper thicknesses that are from 0.5 to 3 oz/ft².

Heavy copper PCBs are primarily used to increase current-carrying capacity and enhance thermal management, which is essential for power electronics and other high-demand applications. By increasing copper mass, the board is able to carry high currents with only minimal increases in trace width compared to using lower copper weights.

These boards, also referred to as thick copper PCBs, can be fabricated with copper weights up to 10 oz/ft².

A four-layer PCB with three layers of one-ounce copper with GETEK dielectrics and one of solid 45-oz Cu base.

Heavy Copper PCB Construction

Heavy copper PCBs are manufactured using four primary methods, each balancing cost, accuracy, and performance.

1. Thin Base, Full Plating

This high-precision but costly method starts with a very thin copper layer. Heavy copper is built up entirely through plating, then the base layer is etched away. Because this approach often requires 20+ hours of plating, it's reserved for high-performance applications where thicker copper in holes improves current capacity and thermal management. Best for fine-line, high-current designs.

2. Mid-Weight Base, Partial Plating

This common method uses a copper layer about half the final desired thickness. Additional copper is plated, then the full thickness is etched. It offers good cost-efficiency, though resolution is lower than the thin-base method. Plated features are more precise than etched ones, and designers must carefully calculate copper buildup in holes.

3. Thick Base, Minimal Plating

In this budget-friendly option, a thick copper base is lightly plated and etched. It’s the least expensive but offers limited trace resolution and poor current handling in holes. Typically used in low-tech applications where performance demands are minimal.

4. Ultra-Thick Copper

Copper thicknesses from 0.020" to 0.040" can be achieved for high-power applications, like Buss Bar replacements. However, extended plating times lead to surface bumps, and imaging through thick photoresist reduces resolution and edge quality. Despite this, the method allows for very robust conductors and high-current paths.

Manufacturing Techniques & Notes

Fabrication of heavy copper boards parallels standard board processes but relies on specialized plating and etching techniques.

Substrate Lamination: Inner layers begin with standard copper foil (0.5 - 2 oz/ft²) laminated onto an FR-4 or alternative substrate. For thick copper, initial copper thickness is often higher to reduce plating time.

The dielectric material may be conventional FR-4 (Tg ~130 °C) or higher-temperature laminates (polyimide, cyanate ester) to tolerate elevated thermal stress.

Copper Plating: Heavy copper features use plating to build up copper thickness on traces, planes, and plated-through holes (PTHs).

Differential etching combines minimal etch back with plating, producing vertical sidewalls and negligible undercut compared to older thick-clad etching methods.

Pattern Etching: After plating, unwanted copper is removed by etching. For thick copper, etch chemistries and tooling are optimized to maintain feature fidelity and to avoid uneven sidewalls.

Heatsink and Thermal Vias: Built-in heatsinks can be electroplated directly onto the board surface, connected via heavy copper thermal vias to internal heat sources. This eliminates the need for post-assembly heatsink attachment and improves overall thermal conductivity.

Heavy Copper PCB

Photo Credit: Robert Tarzwell

Advantages of Copper Core PCBs

Enhanced Current Carrying Capacity

Heavy copper traces allow higher currents through the same footprint compared to standard copper. Inner-layer traces, traditionally de-rated to 50% of outer-layer current capacity, can handle greater loads with heavier copper plating, reducing the risk of thermal failures.

Improved Thermal Management

Thicker copper reduces I²R losses, lowering temperature rise under high current. Integrated heatsinks and copper core layers conduct heat to external dissipation points more efficiently, maintaining stable operating temperatures even in high-power density designs.

Increased Mechanical Strength

Larger copper cross-sections at connector sites and PTHs resist mechanical stresses from vibration and thermal cycling. Heavy copper PTHs provide robustness against cracking under extreme temperature swings (e.g., 25 °C to 260 °C), drastically reducing failure rates during thermal cycle testing.

Space and Cost Optimization

Mixing multiple copper weights on a single layer allows designers to allocate heavy copper only where needed, shrinking board size and reducing layer count. This consolidation can lower material and assembly costs versus stacking parallel 3 oz copper layers to achieve desired current ratings.

Support for Exotic Materials

Heavy copper core PCBs enable designers to exploit high-temperature substrates (e.g., polyimide with Tg ~250 °C) without risking copper crack-outs. Thicker copper in vias and traces mitigates coefficient of thermal expansion mismatches between copper and laminate, extending product life in harsh environments.

How to Choose the Right Copper Thickness

By choosing heavy copper PCB materials and construction, engineers mitigate excessive trace widths, minimize voltage drop, and improve heat conduction - capabilities beyond those of standard copper PCBs.

1. Current Requirements
   • Calculate the maximum continuous current per trace. Use IPC-2221A or equivalent calculators to relate trace width, copper thickness, and allowable temperature rise (typically <30 °C above ambient).
   • For internal layers, assume ∼50 % current capacity compared to external layers.
2. Trace Geometry and Layout
   • Determine minimum trace width and spacing given heavier copper’s plating tolerances. Thick copper requires larger clearances to compensate for increased etch compensation.
   • Employ trace width calculators that iteratively solve for trace width (W), current capacity (I), and ΔT. If two variables are known, the third is derived.
3. Temperature Rise Tolerance
   • Establish maximum permissible temperature rise based on component reliability and substrate Tg. Dielectric materials generally tolerate up to +100 °C above ambient, though most designs target <30 °C rise for reliability.
   • High-temperature substrates allow for higher ΔT but add cost and process complexity.
4. Substrate Material
   • Evaluate dielectric options (FR-4, polyimide) by their Tg, CTE, and cost. A mismatch between copper and laminate CTE can lead to delamination during thermal cycling.
5. Via and Hole Plating
   • Heavy copper PTHs require extended plating times to achieve uniform barrel thickness. Specify via annular ring tolerances accordingly.
   • Thermal vias (heat vias) should be placed strategically under high-power devices to connect to on-board heatsink planes.
6. Mechanical and Environmental Considerations
   • If boards operate under vibration or shock, heavier copper at connectors and PTHs increases mechanical robustness.
   • For extreme environments (military, aerospace), perform thermal cycle testing to verify heavy copper reliability.
7. Cost vs. Performance Trade-offs
   • Heavier copper increases material and plating process costs. Determine if a mixed-weight design (heavy copper only on power layers) can meet performance goals while limiting expense.
   • Consider whether parallel standard copper layers might suffice for moderate current, rather than full heavy copper.

Applications of Heavy Copper PCBs

Heavy copper PCB applications span industries where high current, efficient thermal management, and mechanical durability are paramount:

Military and Defense

• Weapons control systems, power distribution panels, and radar power supplies demand heavy copper for accurate current sharing and reduced thermal stress.
• High-power planar transformers (primary/secondary windings) are implemented directly on the PCB, enabling compact, reliable power modules.

Aerospace and Avionics

• Avionics power supplies, battery management systems, and actuation controls benefit from thick copper’s resilience to extreme temperature cycling and vibration.
• Lightweight heavy copper-based planar transformers improve power density in space- or weight-sensitive platforms.

Industrial Power Electronics

• Variable frequency drives, motor controllers, battery chargers, and power inverters leverage thick copper PCB layers to handle high currents and improve thermal dissipation.
• On-board heatsinks and thermal vias allow dense placement of power semiconductors without external cooling structures.

Automotive and Transportation

• Electric vehicle charging stations, onboard battery management systems, and DC/DC converters require PCBs that manage hundreds of amperes with minimal voltage drop and heat buildup.
• Heavy copper flex PCBs enable reliable power interconnects in constrained engine bay environments.

Read more about PCBs for the Automotive Industry.

Telecommunications and Data Centers

• High-current power distribution, point-of-load converters, and bus bar replacements use heavy copper planes to minimize resistance and thermal hotspots.
• Rack-level power modules integrate heavy copper circuits for efficient power delivery.

Renewable Energy

• Solar inverters, wind turbine controls, and energy storage system power electronics rely on robust heavy copper designs to manage variable loads and harsh outdoor conditions.
• Planar magnetics and embedded heatsinks improve conversion efficiency and system lifespan.

One-Stop Heavy Copper Fab & Assembly

San Francisco Circuits is a single-source provider for heavy copper PCB fabrication and assembly, offering engineers a streamlined path from prototype to production:

Our engineers have deep experience in heavy copper layouts, including copper core PCBs, copper PCB flex constructions, and assemblies. We can guide customers through selecting the optimal copper weight based on load requirements, thermal margins, and mechanical constraints.

Our speciality lies in quick-turn prototypes ideal for validating heavy copper PCB designs and performing thermal cycle testing, while scaling to production quantities without sacrificing quality.

Beyond bareboard fabrication, SFC offers turnkey PCB assembly, including soldering of power semiconductors and attachment of on-board heatsinks.

Leveraging advanced equipment capabilities and streamlined workflows, we offer aggressive lead times on heavy copper PCB fabrication.