Buy High-Quality Heavy Copper PCBs from China Factory: Ideal for Power Converters and Strong Current Applications – Top Suppliers Company, Factory
Product Description
What is Heavy Copper PCB?
Core Features and Application Scenarios
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.
The thick copper layer can quickly conduct heat, reducing the risk of overheating of the device.
Thick copper enhances the PCB's resistance to bending and impact, improving overall durability.
Power converters (AC-DC / DC-DC), BMS for new energy vehicles, industrial frequency converters, control boards for welding machines, etc.
Key Design Points
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.
Current-carrying capacity calculation:
The current-carrying capacity of thick copper trace needs to be combined with the 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:
• For high-current traces, keep them as short and wide as possible to avoid narrow necks (sudden changes in line width can easily lead to local overheating).
• The high-current circuit of multi-layer boards can adopt "parallel connection of multiple layers of copper foil" (e.g., 2 layers of 2 oz copper ≡ 4 oz) to enhance current-carrying capacity.
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.
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: The wire spacing for thick copper layers should be widened (for 70μm copper, the corresponding wire spacing should be ≥0.2mm) to prevent creepage breakdown under high voltage.
Manufacturing Process Difficulties and Control
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.
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%).
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.
