Heavy Copper PCB

Beyond Standard Traces: The Heavy Copper Advantage

Heavy Copper PCBs utilize copper weights from 3 oz(105µm)to 20 oz(700µm)or more, significantly exceeding the 1-2 oz standard.The technology's advantages stem from three core principles:

● High Current Capacity: Increased cross-sectional area reduces resistive heating(I²R), enabling sustained high-current operation.

● Integrated Thermal Management: The thick copper layer acts as an embedded heat spreader, efficiently dissipating heat from power components.

● Structural Robustness: Provides mechanical support for heavy components and connectors, enhancing board durability.

This makes Heavy Copper PCBs critical for high-reliability applications where performance and longevity are paramount, such as power converters, motor drives, and automotive control systems.

Manufacturing Process&Material Considerations

Fabricating Heavy Copper PCBs requires specialized processes to manage the extreme copper thickness.

Core Manufacturing Techniques:

● Step Plating: Copper is selectively plated to specific areas in multiple stages, allowing for different copper weights on the same layer(e.g., 4oz in power sections, 2oz in signal sections).

● Differential Etching: A combination of thick photoresist and specialized etch chemistry is used to achieve well-defined sidewalls without over-etching the fine-feature traces.

● Controlled Lamination: Managing the increased copper volume requires careful preparation of prepregs and press parameters to prevent resin starvation and ensure proper fill, especially when combining heavy copper with standard layers.

Material Selection for Reliability:

● Substrates: Standard FR-4 is often used, but for the highest thermal stress applications, High-Tg FR-4, Epoxy-Based Laminates, or Ceramic-Filled Thermally Conductive Materials are recommended.

● Surface Finishes: ENIG provides a flat, reliable surface.HASL(Lead-Free)is a robust, cost-effective option.For the highest power connections, Selective Electrolytic Thick Gold is often specified.

Primary Applications&Industries

This technology is essential where high power and reliability intersect.

Power Conversion&Distribution:

Power Supplies: AC/DC, DC/DC converters, UPS systems.

Renewable Energy: Solar inverter busbars, wind turbine controls.

Industrial Controls: Motor drives, welding equipment, PLC power stages.

Automotive&Transportation:

EV/HEV Systems: Battery Management Systems(BMS), onboard chargers, traction control.

Power Distribution Units(PDUs): 12V/48V distribution in modern vehicles.

Aerospace, Defense&Industrial:

Power Controllers: Actuator controls, radar power systems.

High-Reliability Infrastructure: Telecom rectifiers, railway signaling power.

"Design for Power" Guide: Critical Rules for Success

Designing with Heavy Copper requires attention to thermal and mechanical stresses.

Our Recommended Heavy Copper Design Practices:

Design Parameter	Recommended Practice(For High Reliability)	Common Pitfall to Avoid
Trace Width for Current	Use IPC-2152(modified)charts.For 100A in 10oz copper, a 15mm+trace width may be required.	Under-sizing traces based on obsolete IPC-2221 standards, leading to overheating.
Copper Transitions	Use gradual tapers or stepped increases in trace width when connecting different copper weights.	Abrupt changes in copper cross-section, creating stress concentration points.
Thermal Relief	Essential for soldering to heavy copper planes.Use wide spokes to ensure mechanical strength while managing heat during soldering.	Poor thermal relief, causing cold solder joints or excessive heating time.
Plated Through-Holes(PTHs)	Specify a minimum 1.5 mils(0.038mm)of plating per oz of copper to ensure a robust barrel.	Inadequate PTH plating thickness, leading to barrel cracking during thermal cycling.
Solder Mask	Specify Solder Mask Over Defined Traces(SMD)to prevent solder wicking onto thick traces.	Solder mask webbing between close, thick traces can be challenging;consult us for minimum spacing.
DFM Collaboration	Engage us early for stack-up review and manufacturability analysis of your power-to-signal layer transitions.	Assuming all fabricators can process extreme copper weights without a dedicated DFM review.

Pro Tip: Utilize our Free Heavy Copper DFM Service!Our power electronics specialists will analyze your current requirements, thermal loads, and mechanical design to recommend the optimal copper weight, trace geometry, and stack-up.

Our Heavy Copper PCB Manufacturing Capabilities

We are equipped with the advanced plating lines and lamination presses required for high-yield Heavy Copper production.

Technical Specifications:

Finished Copper Weight Range: 3 oz to 20 oz(105µm to 700µm).

Maximum Layer Count: 12 layers with heavy copper construction.

Minimum Trace/Space(for 3 oz Cu): 8/8 mil(0. 20mm/0. 20mm). Note: Increases with copper weight.

Aspect Ratio for PTH: Up to 12: 1 for high-thickness boards.

Mixed Copper Weights: Supported via step-plating technology.

Surface Finishes: ENIG,HASL,Immersion Tin,Selective Hard Gold.

Quality&Assurance:

Standards: Fabricated and inspected to IPC-6012 Class 2/3 with specific criteria for plated-hole integrity.

Testing: 100%Electrical Testing. Cross-sectioning to verify PTH copper thickness.

Current Testing: Custom current-load testing available upon request.