OEM Heavy Copper PCB Company, Quotes
Product Description
What is Heavy Copper PCB?
Core Features and Application Scenarios
Core Advantages
- Strong current-carrying capacity: The current-carrying capacity of 70μm copper foil (2 ounces) is approximately twice that of 35μm copper foil (1 ounce) (under the same line width).
- Good heat dissipation: The thick copper layer can quickly conduct heat, reducing the risk of overheating of the device.
- 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
Selection of Copper Foil Thickness
- Common specifications: 70μm (2 ounces), 105μm (3 ounces), 140μm (4 ounces), and up to 420μm (12 ounces) in extreme scenarios.
- Matching scenarios: For large current (≥5A) circuits, 2 to 4 ounces of copper should be preferred. For ultra-power scenarios (≥20A), 6 to 12 ounces of copper should be selected.
Trace and Current-Carrying Capacity Design
- 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℃). The formula reference is: I = K × W × T0.83 (I is the current, K is the coefficient, W is the line width, and T is the copper thickness). Example: 2 ounces of copper (70μm), wire width 5mm, current carrying capacity approximately 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" (for example, 2 layers of 2 ounces of copper are equivalent to 4 ounces) to enhance the current-carrying capacity.
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 (8 to 12μm for ordinary PCBs).
- Pads: Thick copper pads need to be enlarged in size (0.2 to 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 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: 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
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
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
What copper thickness is considered "Heavy Copper"?
Typically, PCBs with copper weights of 2 oz/ft² (70μm) to 4 oz/ft² (140μm) are classified as heavy copper. Severe high-power boards can utilize extreme copper weights up to 12 oz (420μm).
Why do heavy copper PCBs dissipate heat better than standard PCBs?
The thick copper layers feature a significantly higher thermal conductivity, effectively acting as integrated heat sinks that transfer heat away from power-sensitive components.
What are the primary applications of heavy copper boards?
They are predominantly utilized in high-power conversion modules (AC-DC/DC-DC), EV battery management systems (BMS), solar power converters, and industrial welding control equipment.
What surface finish is best suited for heavy copper PCBs?
High-temperature tin plating or Electroless Nickel Immersion Gold (ENIG) is strongly recommended over OSP to protect the thick traces from oxidation and provide strong solder joint integrity.
How does manufacturing heavy copper boards prevent warpage?
Fabricators employ symmetrical lamination stack-ups with consistent copper weights between layers along with rigid structural supports to counterbalance CTE mismatches.
