What Is Heavy Copper PCB?
In PCB (Printed Circuit Board) manufacturing, copper thickness refers to the thickness of the copper layer, typically measured in ounces (oz). 1 oz means that the weight of 1 oz of copper is evenly spread over an area of 1 square foot (ft²), resulting in a specific thickness. The thickness of 1 oz copper is approximately 35 micrometers (um) or 1.4 mils. Heavy copper PCBs, as the name suggests, involve the use of relatively thicker copper layers in the conductive layers of the PCB. Typically, standard PCBs have copper layer thicknesses ranging from 1oz (ounce) to 3 oz, while thick copper PCBs may exceed this range, even reaching 15 oz or higher. This design can effectively enhance the PCB’s conductivity and its ability to carry high currents, ensuring stability in high-current, high-power operating environments. Using Heavy copper PCBs can effectively meet the current-carrying requirements of the circuits while also improving the PCB’s thermal performance.
Research on Heavy Copper PCB Production Technology
1.Technical Difficulties of Heavy Copper PCB
Heavy copper PCBs (with copper thickness ≥ 3oz) are widely used in power modules, automotive electronics, and industrial control due to their high current-carrying capacity and excellent thermal performance. However, their manufacturing process is complex and requires overcoming technical challenges in etching, plating, and lamination.
2. Characteristics of Heavy Copper PCBs
Heavy copper PCBs feature high current-carrying capacity, excellent thermal performance, and high mechanical strength, making them suitable for applications requiring high current, high power, and high reliability, such as power modules, automotive electronics, and industrial control equipment.
3. Challenges in Manufacturing Process
The main challenges in manufacturing heavy copper PCBs include side etching and uneven etching during the etching process, difficulty in achieving uniform copper thickness during plating, and the risk of bubbles or delamination during lamination, all of which directly affect the performance and reliability of the PCB.
4. Optimization of Etching Process
In the etching process of thick copper PCB, the difficulty of changing the solution increases, and the amount of side etching will also increase. It is necessary to solve the problem of increasing side etching by multiple rapid etchings and increasing the etching compensation coefficient.
QFPCB has customized a special DES etching line for thick copper, which can achieve one-time etching of 6oz Heavy copper PCB.high-precision etching equipment can be used to ensure uniformity, and the etching solution formula can be optimized to improve etching rate and accuracy, ensuring fine and consistent circuit patterns.
5. Improvement of Plating Process
In the plating process, pulse plating technology can be employed to enhance the uniformity and density of the copper layer. Additionally, optimizing the plating solution composition and parameters, along with introducing auxiliary anodes to improve current distribution, ensures consistent thickness and conductivity of the heavy copper layer.
6. Control of Lamination Process
In the lamination process, vacuum lamination technology can effectively reduce bubbles and delamination issues. By optimizing temperature and pressure parameters, the bonding strength between the heavy copper layer and the substrate is ensured, and high-adhesion materials are used to further enhance interlayer bonding.
In the lamination process, due to the deep line gap, under the same residual copper rate, it is necessary to select multiple prepregs with good fluidity to meet the resin filling requirements. At the same time, rivets need to be added to strengthen the fixation between core boards and reduce the risk of sliding. The increase in copper thickness of PCB leads to a slower actual heating rate of the board during lamination. It is necessary to increase the duration of the high temperature section and increase the curing effect of the prepreg.
QFPCB uses Burkle multi-layer lamination fully automatic production line and special browning solution for thick copper to ensure the lamination quality of Heavy copper PCB. At present, through the combination of Mass LAM and Pin LAM, up to 30 layers of thick copper PCB can be produced.
7. Drilling of Heavy copper PCB
During the drilling process, when the thickness of the Heavy copper plate is above 2.0mm, segmented drilling can be used to solve the problem of drilling difficulty. At the same time, the relevant parameters of the feed speed and the retract speed can be adjusted to optimize the drilling quality, reduce the cutting speed, and avoid the problem of thick copper pad cracking.
8.Solder mask for Heavy copper PCB
During the solder mask printing process, due to the deep line gap, the height difference between copper and PCB substrate will cause oil flow, insufficient oil thickness, red lines, pinhole bubbles and other problems. It is necessary to dilute the ink viscosity and use multiple printing methods to solve a series of problems in solder mask printing.
QFPCB adopts a fully automatic solder mask spraying line, using pretreatment + double-sided spraying + pre-baking + fully automatic connection technology. By using a special high-pressure nozzle + high-viscosity brand ink, 4OZ thick copper can be sprayed in one time. The solder mask thickness is uniform and weldability is friendly.
9. Material Selection
Material selection is critical for heavy copper PCBs. High-Tg, low-CTE substrates (such as FR-4, CEM-3), high-purity, low-roughness copper foil to ensure conductivity and bonding strength, and high-adhesion prepregs are essential to guarantee lamination quality.
10. Inspection and Quality Control
Quality control for heavy copper PCBs includes using X-ray or ultrasonic equipment to detect copper thickness uniformity, evaluating conductivity through four-probe or micro-resistance testing, assessing thermal performance using thermal imaging or thermal resistance testers, and testing mechanical performance through peel strength and bending tests.
Relationship between PCB copper thickness, line width, temperature and current
Below is a table showing the relationship between PCB copper thickness, trace width, temperature, and current, based on the IPC-2221 standard and other relevant design guidelines. These values are theoretical references and should be adjusted according to specific design conditions and environments in practical applications.
4 oz (140 µm)0.2104.8Suitable for designs with ultra-high current density
| Copper Thickness (oz) | Trace Width (mm) | Temperature Rise (°C) | Maximum Current Capacity (A) | Notes |
|---|---|---|---|---|
| 1 oz (35 µm) | 0.2 | 10 | 1.2 | Low-current applications, suitable for general signal traces |
| 1 oz (35 µm) | 0.5 | 10 | 3.0 | Suitable for medium-current scenarios |
| 1 oz (35 µm) | 1.0 | 10 | 6.0 | Suitable for higher-current scenarios |
| 2 oz (70 µm) | 0.2 | 10 | 2.4 | Suitable for designs with higher current density |
| 2 oz (70 µm) | 0.5 | 10 | 6.0 | Suitable for power line designs |
| 2 oz (70 µm) | 1.0 | 10 | 12.0 | Suitable for high-current scenarios |
| 3 oz (105 µm) | 0.2 | 10 | 3.6 | Suitable for designs with high current density |
| 3 oz (105 µm) | 0.5 | 10 | 9.0 | Suitable for high-current power lines |
| 3 oz (105 µm) | 1.0 | 10 | 18.0 | Suitable for ultra-high-current scenarios |
| 4 oz (140 µm) | 0.5 | 10 | 12.0 | Suitable for high-power power designs |
| 4 oz (140 µm) | 1.0 | 10 | 24.0 | Suitable for ultra-high-power scenarios |
Table Notes:
- Copper Thickness: Measured in ounces (oz), where 1 oz ≈ 35 µm.
- Trace Width: Refers to the width of the PCB trace, measured in millimeters (mm).
- Temperature Rise: Refers to the increase in temperature of the PCB relative to the ambient temperature, measured in degrees Celsius (°C).
- Maximum Current Capacity: Refers to the maximum current that the trace can safely carry under specific temperature rise conditions, measured in amperes (A).
- Notes: Describes applicable scenarios or design recommendations.
Key Points:
- Copper Thickness and Current: As copper thickness increases, the cross-sectional area of the trace increases, significantly enhancing current-carrying capacity.
- Trace Width and Current: As trace width increases, the cross-sectional area of the trace increases, improving current-carrying capacity.
- Temperature Rise and Current: Higher temperature rise reduces the current-carrying capacity of the trace, so temperature rise must be controlled during design to ensure reliability.
- Design Recommendations: For high-current scenarios, it is recommended to use thick copper (≥2 oz) and wider traces, along with optimized thermal management to control temperature rise.
For more precise calculations, the formulas in the IPC-2152 standard or online PCB current-carrying capacity calculators can be used for detailed analysis.
Heavy Copper PCBs: A Key Technology from High-Power Supplies to Medical Devices
Heavy copper PCBs (Printed Circuit Boards) are gaining significant attention due to their exceptional current-carrying capacity and heat dissipation performance. These attributes make them essential components in a wide range of applications, from high-power power supplies to industrial motors, electric vehicles, charging stations, inverters, industrial energy storage, aerospace, medical devices, and even consumer electronics. This article explores the diverse applications of Heavy copper PCBs across different industries, emphasizing their crucial role in ensuring reliability, efficiency, and high performance in demanding environments.
1. High-Power Power Supplies
High-power power supply modules are one of the primary application areas for thick copper circuit boards. In data centers, communication base stations, industrial equipment, and renewable energy systems, these power modules need to carry extremely high currents while ensuring efficient energy conversion and heat dissipation. Heavy copper PCBs’ high conductivity and excellent thermal management effectively address these challenges.
- Data Centers: In server power supplies and UPS (uninterruptible power supply) systems, thick copper PCBs can carry large currents and quickly dissipate heat, ensuring stable operation under heavy load.
- Communication Base Stations: 5G base stations and communication devices require efficient and reliable power support, and thick copper PCBs meet the high-power demands while minimizing heat loss.
- Industrial Equipment: Thick copper PCBs are used in high-power supply modules for industrial automation systems, ensuring long-term stable operation in harsh environments.
2. Industrial Motors
Industrial motors operate in high-current and high-temperature environments, placing high demands on PCB current-carrying capacity and heat dissipation performance. Thick copper PCBs are critical for maintaining the efficiency and reliability of these systems.
- Motor Control Systems: Thick copper PCBs are used in motor drivers and controllers to handle large currents and ensure efficient operation.
- Variable Frequency Drives (VFDs): In industrial VFDs, thick copper PCBs can withstand high current and temperature conditions, increasing reliability and extending service life.
- Heavy Machinery: In heavy equipment such as mining machinery and cranes, thick copper PCBs are used in high-power motor control systems to ensure stable operation under extreme conditions.
3. Electric Vehicles
The rapid development of electric vehicles (EVs) has led to a significant demand for thick copper PCBs. EVs require PCBs that can handle high currents and offer excellent heat dissipation, particularly for the battery management system (BMS), motor control system, and charging system.
- Battery Management Systems (BMS): Heavy copper PCBs are used in current sensing and balancing modules within BMS to carry large currents and improve battery safety and lifespan.
- Motor Control Systems: In EV motor controllers, Heavy copper PCBs support high currents and provide rapid heat dissipation, ensuring efficient motor operation.
- Charging Systems: Thick copper PCBs are used in onboard chargers and charging stations to carry large currents and reduce heat loss, enhancing charging efficiency.
4. Charging Stations
As electric vehicle adoption grows, the demand for charging stations has surged. Charging stations generate significant heat during operation, demanding superior thermal management from PCBs.
- DC Fast Charging Stations: Thick copper PCBs are used in power modules for DC fast chargers, capable of handling high currents and dissipating heat efficiently to boost charging efficiency.
- AC Charging Stations: In AC charging stations, thick copper PCBs are employed in power management and control systems, ensuring stable operation under heavy loads.
- Thermal Management: The high thermal conductivity of thick copper PCBs effectively reduces the operating temperature of charging stations, extending the equipment’s service life.
5. Inverters
Inverters are key components in solar and wind energy systems, operating in high-current and high-temperature environments. The high current-carrying capacity and temperature resistance of thick copper PCBs make them ideal for inverter applications.
- Solar Inverters: Thick copper PCBs are used in power modules for solar inverters, carrying large currents and effectively dissipating heat to enhance energy conversion efficiency.
- Wind Energy Inverters: In wind power systems, thick copper PCBs are used in inverter control systems, ensuring reliable operation under extreme environmental conditions.
- Home Inverters: For home solar inverters, thick copper PCBs provide high current support, reducing heat loss and increasing system reliability.
6. Industrial Energy Storage
Industrial energy storage systems require thick copper PCBs to carry large currents while ensuring efficient energy conversion and heat dissipation.
- Battery Energy Storage Systems (BESS): Thick copper PCBs are used in power management and control systems, ensuring efficient heat dissipation and system reliability.
- Grid Storage Systems: In grid storage, thick copper PCBs are used in high-power modules to ensure stable operation under high loads.
- Distributed Energy Storage Systems: Thick copper PCBs are utilized in distributed storage systems to carry large currents and minimize heat loss, improving energy conversion efficiency.
7. Aerospace
The aerospace industry demands extremely high reliability and performance for its electronic systems. Thick copper PCBs, with their high current-carrying capacity, heat resistance, and thermal management, are well-suited for aerospace applications.
- Aviation Power Systems: Thick copper PCBs are used in aviation power modules, capable of carrying high currents and providing efficient heat dissipation to ensure stable operation at high altitudes.
- Spacecraft Control Systems: In spacecraft, thick copper PCBs are used in high-power modules, ensuring reliable operation in extreme conditions.
- Satellite Power Systems: Thick copper PCBs are used in satellite power management systems to handle large currents and reduce heat loss, improving system longevity.
8. Medical Devices
The medical device industry requires high reliability and performance for its electronic components. Thick copper PCBs are ideal for use in medical equipment, where reliability is critical.
- Medical Imaging Equipment: Thick copper PCBs are used in power modules for CT scanners, MRI machines, and other medical imaging devices, ensuring efficient operation and heat dissipation.
- Surgical Equipment: In surgical equipment, thick copper PCBs are used in high-power modules, ensuring stability during prolonged operation.
- Medical Monitoring Equipment: Heavy copper PCBs are used in ECG monitors, blood pressure monitors, and other medical devices to provide reliable power while minimizing heat loss.
9. Consumer Electronics
Although Heavy copper PCBs are primarily used in high-power and high-reliability fields, they also find applications in certain high-end consumer electronics.
- High-Performance Computers: Heavy copper PCBs are used in power modules for high-performance computers, handling large currents and ensuring efficient cooling.
- Game Consoles: In gaming consoles, Heavy copper PCBs are used in power modules to maintain stability under heavy loads.
- Smart Home Devices: Thick copper PCBs are used in power modules for smart home devices, ensuring reliability while minimizing heat loss.
Heavy copper PCBs have a wide range of applications, including high-power power supplies, industrial motors, electric vehicles, charging stations, inverters, industrial energy storage, aerospace, medical devices, and consumer electronics. With continuous technological advancements and increasing market demand, Heavy copper PCBs will continue to play an important role in driving the power electronics industry toward higher performance and reliability. Designers and manufacturers who fully understand the characteristics and advantages of Heavy copper PCBs will be better equipped to meet the demands of future markets.