A new trend in the printed circuit board business, Heavy Copper, and Extreme Copper Printed Circuit Boards, is being tapped into by an increasing variety of power electronics products. The majority of PCBs that are sold commercially are made for low-voltage/low-power applications, and their copper traces and planes are composed of copper weights that range from 1/2 to 3 ounces per square foot. Copper weights for a hefty copper circuit can range from 4 to 20 ounces per square foot. Extreme Copper refers to copper weights that are above 20 oz/ft2 and can reach up to 200 oz/ft2. We’ll be talking mostly about heavy copper thickness.

Heavy copper thickness in PCB manufacturing process 

Standard printed circuit boards are created by combining copper etching and plating techniques, regardless of whether they are double-sided or multilayered. Initially, circuit layers are made of thin copper foil sheets (usually 0.5 to 2 oz/ft2) that are etched to remove excess copper and then plated to give planes, traces, pads, and plated-through holes more copper thickness. The circuit layers are assembled into a comprehensive package by laminating them onto an epoxy-based substrate, like polyimide or FR4.

The production process for boards with heavy copper circuitry is the same, but specific etching and plating methods, like differential etching and high-speed/step plating, are used. In the past, thick copper-clad laminated board material was totally etched to create heavy copper features. This resulted in uneven trace sidewalls and unacceptably high undercutting. The combination of plating and etching has made it possible to manufacture hefty copper features with straight sidewalls and minimal undercut because to advancements in plating technology.

The Advantages of Heavy Copper PCB

  • Better thermal performance: During the manufacturing and assembly procedures, heavy copper printed circuit boards (PCBs) can tolerate numerous temperature cycles.
  • Greater current carrying capacity: PCBs made of heavier copper have larger current capacities and better electrical conductivity. The current carrying capability can be increased by widening the copper trace, and even higher current loads can be supported by thicker copper traces.
  • Enhanced mechanical strength: PCBs made of heavy copper have stronger connections and plated-through holes, which guarantees the board’s structural integrity and increases the electrical system’s resilience to voltage.
  • Outstanding dissipation factor: PCBs made of heavy copper work well with big power-loss components. These PCBs have the ability to efficiently disperse heat and stop electrical systems from overheating.
  • Good conductor: Heavy copper PCBs are useful in the manufacture of electrical items because they are good conductors. They assist in joining different boards so that currents can be transmitted.

Applications for PCBs Made of Heavy Copper

Because heavy copper PCBs are widely used in the following industries, their popularity is growing:

  • Military: Radar, weapon control, and surveillance systems.
  • Rails Tracking: Rail track system and signal transmission system for the automotive sectors.
  • Power distribution: High power rectifiers, power grid switching systems, overload relays, and excitation systems for power regulators.
  • Transportation: Traction converters, power line monitors, and power converters for railroad systems.
  • Industrial controls: Surge protectors, protection relays, welding equipment, safety, and signal systems. 
  • Renewable Systems: Control panels for hydroelectric power facilities, energy storage, power grid backup, and power converters.

 Services offered by PCB Runner include PCB Assembly (SMT), Electronics Module Sales, CNC Machining, PCB Prototype & Batch Production, and more. We are dedicated to satisfying the demanding demands of international manufacturers across many industries with regard to electronics quality, delivery, affordability, and other matters.

Heavy Copper Thickness PCB Design Guidelines

The following are some important design factors for PCBs made of heavy copper:

Layer Assembling

  • To reduce warpage, place thick copper layers close to the board’s core.
  • Avoid positioning outer layers adjacent to one another as this can worsen registration problems.
  • For stability, rotate the direction of the fiber weave by ninety degrees between neighboring dielectric layers.

Part Location

  • To ensure solder mask coverage, make sure there is enough space between plane layers.
  • Take into consideration component shadows that fall on inner copper layers.
  • Inspect drilled holes for exposed copper.

Temperature Control

  • To serve as heat spreaders, place heat-generating components on top of thick copper layers.
  • Provide many vias to distribute heat to the interior planes underneath heated components.
  • Elevated Current Pathways
  • For high-current lines, use copper pouring or polygons rather than routing several parallel traces.
  • For heat dissipation, place next to plated thru-hole vias.
  • The use of filled vias should be restricted since, in comparison to hollow vias, they hinder heat transfer.
  • Solder masks should be kept free of holes and countersink-filled vias.

Panel and Tooling

Give ample room for manufacturing and assembly tolerances. Consider warpage, stretching, and shrinkage of the cloth. For simple tooling, use fiducials and test coupons on the panel.

DFM Evaluation

During the design phase, ask the fabricator for DFM feedback.

In particular, look into manufacturability with regard to heavy copper tolerance concerns.

Getting in touch with the PCB maker early on streamlines the design process and helps to prevent problems during the prototype.

Finding the Right Heavy Copper Partner

Make sure the PCB manufacturer you choose for your heavy copper boards satisfies the following requirements.

Checklist of Capabilities

  • Lamination thicknesses of 2 oz, 3 oz, 4 oz, and so on are available.
  • PTH filling: epoxy plugs, conductive ink, and copper
  • Preferred registration accuracy is ≤ 0.003″.
  • Etching with fine lines: < 4 mil line/space
  • The thickness of plating: ≥ 2.5 mils copper in holes
  • Gaps to be filled by sectional plating after etch AOI examination – 5+ high-resolution cameras.

Standards and Licensure

  • Shop floor processes in accordance with IPC 6012 Class 3
  • ISO 9001 certified
  • UL or TUV-approved facilities
  • Qualification testing- vibration, shock, and thermal stress

Technical Proficiency

  • Familiarity with intricate copper designs
  • Support for Design for Manufacturing (DFM)
  • Simulated plane currents and thermal analysis
  • Comments on dependability, stacking, and layout

Active Prototyping

  • Minimal NRE expenses
  • There are no minimum order requirements.
  • Compact panel or array sizes
  • Simple 2-4 layer constructions can be completed in 24 hours.

Examine manufacturers carefully based on these factors prior to selecting your heavy copper PCB supplier.

Read More: PCB Component Placement Guide – Everything You Should Know For Effective PCB Assembly! 


Applications with large current loads, demands for thermal performance, and requirements for power integrity are made possible by heavy copper PCB technology. Although the thick copper layers increase reliability, strict process controls are required during fabrication. The benefits of heavy copper PCBs in your product can be realized by closely collaborating with the PCB manufacturer throughout the design phase and adhering to layout specifications. Heavy copper fabrication calls for specific accuracy and knowledge, thus working with a reputable manufacturer that offers design reviews and qualification testing yields the best results.


When is the high copper thickness required?

Applications that need power conversions, thermal dissipation, high power distribution, and planar transformers require PCBs with high copper thickness.

Are there any trace width & and spacing restrictions while using high coppers?

High signal count parallel buses or very fine pitch BGAs are examples of PCB footprints used in high-density designs that may call for trace widths as thin as 2.5 mils and unique via types such as laser-drilled micro-vias with diameters of no more than 6 mils. On the other hand, some high-power designs may call for thicker ounce pours than usual and very big traces or planes that consume a complete layer. Applications with limited space may call for extremely thin boards with multiple layers and a half-ounce (0.7 mil) maximum copper pour thickness.

Can high copper traces impact power noise?

Copper traces on PCBs are crucial. Heavy copper can be used to narrow the track width in high-power printed circuit board production while maintaining the same current capacity. The circuit board’s area of occupancy decreases with decreasing PCB track width. In addition, copper busbars for high power and high current can be welded to PCB pads. 

Why Us?

PCB Runner offers Heavy copper clads manufacturing based on high current design requirements, we provide reliable & good quality circuit boards and maintain the required high voltage calculations. Submit your Gerber files at https://www.pcbrunner.com/free-pcb-quote/ or do reach out to our team offline at engineering@pcbrunner.com or sales@pcbrunner.com for your current or upcoming project’s needs.