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China Heavy Copper PCB Suppliers in China - High Capacity Power Solutions from a Reliable Factory for Optimal Heat Dissipation Manufacturer, Factory
Product Description
What is Heavy Copper PCB?
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The core is used in high-current and high-power scenarios (such as power supplies, new energy, industrial control, etc.). The key points of its design, manufacturing and application are as follows:
Core Features and Application Scenarios
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Strong Current-Carrying Capacity
The current-carrying capacity of 70μm copper foil (2 oz) is approximately twice that of 35μm copper foil (1 oz) under the same line width.
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Good Heat Dissipation
The thick copper layer can quickly conduct heat, reducing the risk of overheating of the device.
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High Mechanical Strength
Thick copper enhances the PCB's resistance to bending and impact.
Typical Applications: Power converters (AC-DC / DC-DC), BMS for new energy vehicles, industrial frequency converters, control boards for welding machines, etc.
Key Design Points
1 Selection of Copper Foil Thickness
- Common specifications: 70μm (2 oz), 105μm (3 oz), 140μm (4 oz), and up to 420μm (12 oz) in extreme scenarios.
- Matching scenarios: For large current (≥5A) circuits, 2–4 oz copper is preferred. For ultra-power scenarios (≥20A), 6–12 oz copper should be selected.
2 Trace and Current-Carrying Capacity Design
- Current-carrying capacity calculation: Needs to be combined with copper thickness, line width, and temperature rise requirements (usually designed based on a temperature rise of 10℃).
- Formula reference: I = K × W × T0.83 (I = current, K = coefficient, W = line width, T = copper thickness). Example: 2 oz copper (70μm), wire width 5mm → current-carrying capacity ≈ 15A (temperature rise 10℃).
- Trace optimization: Keep high-current traces as short and wide as possible to avoid narrow necks. Multi-layer boards can adopt "parallel connection of multiple copper layers" (e.g., 2 layers of 2 oz = 4 oz equivalent) to enhance current-carrying capacity.
3 Via and Pad Design
- Vias: For high-current vias, the hole diameter should be increased (≥0.5mm), the number of vias should be increased (estimated at 1A per hole), and the copper plating thickness on the hole wall should be ≥20μm (vs. 8–12μm for ordinary PCBs).
- Pads: Thick copper pads need to be enlarged in size (0.2–0.5mm larger than ordinary pads) to prevent the copper layer from dissipating heat too quickly during welding, which may lead to false soldering.
4 Heat Dissipation and Insulation Design
- Heat dissipation: The thick copper area can be designed as a "copper sheet heat sink", or a metallized via array (via spacing ≤1mm) can be added to connect to the heat dissipation layer.
- Insulation: Wire spacing for thick copper layers should be widened (for 70μm copper, wire spacing should be ≥0.2mm) to prevent creepage breakdown under high voltage.
Manufacturing Process Difficulties and Control
🔧 1. Copper Foil Lamination and Etching
Thick copper lamination: High-temperature and high-pressure lamination (180℃ / 4MPa) is required to ensure the peel strength between the copper foil and the substrate (≥1.2N/mm).
Thick copper etching: The etching rate is slow (about 1μm/min), and the etching time needs to be controlled to avoid side etching (side etching amount ≤0.05mm). A stepwise etching process should be adopted to reduce line width deviation.
📐 2. Lamination and Warpage Control
The coefficient of thermal expansion (CTE) of thick copper layers differs significantly from that of the substrate. When laminating, a "symmetrical structure" (with consistent copper thickness between the upper and lower layers) should be adopted, and a rigid support layer should be added to prevent PCB warping (warping degree ≤0.5%).
✨ 3. Surface Treatment
The surface of thick copper is prone to oxidation. It is preferred to choose tin plating (high-temperature tin layer) or nickel-gold plating to avoid OSP (incomplete organic film coverage).
The pad area needs to be enlarged with a "solder mask opening window" to ensure the bonding force between the solder and thick copper.
Core Summary
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The core of heavy copper PCBs is "high current carrying capacity + heat dissipation". In terms of design, it is necessary to match the copper thickness and current carrying capacity requirements. In manufacturing, problems such as thick copper etching and lamination warping need to be solved. They are suitable for high-power and high-current industrial and energy scenarios.
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Frequently Asked Questions (FAQ)
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What is the minimum copper thickness considered "heavy copper" in PCB manufacturing?
Heavy copper PCBs are generally defined as boards with a copper thickness of 3 oz (105μm) or more. However, in many industry contexts, boards starting from 2 oz (70μm) are already classified as heavy copper, especially when compared to the standard 1 oz (35μm) used in conventional PCBs.
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How does copper thickness affect the current-carrying capacity of a PCB trace?
Copper thickness directly impacts current-carrying capacity. For example, a 2 oz (70μm) copper trace can carry approximately twice the current of a 1 oz (35μm) trace at the same line width. The relationship follows the formula I = K × W × T0.83, where I is current, K is a process coefficient, W is line width, and T is copper thickness. Thicker copper allows narrower traces to handle higher currents with lower temperature rise.
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What are the main challenges in manufacturing heavy copper PCBs?
The key manufacturing challenges include: (1) Etching control — thick copper etches more slowly and is prone to side etching, requiring precise process timing and stepwise etching techniques. (2) Lamination warpage — the mismatch in CTE between thick copper and the substrate can cause board warping, which is controlled through symmetrical layer structures and rigid support layers. (3) Surface treatment — thick copper surfaces oxidize easily, making tin plating or nickel-gold plating preferable over OSP.
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Which industries and applications most commonly use heavy copper PCBs?
Heavy copper PCBs are widely used in high-power and high-current applications, including: power converters (AC-DC and DC-DC), battery management systems (BMS) for electric vehicles, industrial frequency converters, welding machine control boards, solar energy inverters, and military or aerospace power systems. Any application requiring sustained high current (≥5A) or robust heat dissipation is a strong candidate for heavy copper PCB design.
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How should vias be designed on heavy copper PCBs to handle high current?
For high-current vias on heavy copper PCBs, the following design rules are recommended: increase the hole diameter to ≥0.5mm, add multiple vias in parallel (estimated at 1A per via as a general guideline), and ensure the copper plating thickness on the hole wall is ≥20μm — significantly thicker than the 8–12μm used in standard PCBs. This ensures reliable current conduction and prevents localized overheating at via points.
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Can heavy copper layers be used in multi-layer PCB designs to increase current capacity?
Yes. In multi-layer PCB designs, multiple copper layers can be connected in parallel to effectively increase the total current-carrying capacity. For example, connecting two layers of 2 oz copper in parallel is functionally equivalent to a single 4 oz copper layer. This approach also helps distribute heat more evenly across the board, improving overall thermal performance and reliability in demanding power applications.
