From the power system of new energy vehicles, to the high-power drive devices in industrial automation, to the high-efficiency power modules in data centers, high-current PCB boards play a key supporting role in the stable operation of these devices. The following will deeply analyze the relevant content of high-current PCB boards.
Characteristics of high current PCB boards
The most significant difference between high-current PCB boards and ordinary PCB boards is their strong current carrying capacity. The copper foil thickness of general PCB boards is mostly 1 ounce, while the copper foil thickness of high-current PCB boards usually starts from 2 ounces and can even reach 20 ounces. Taking the common 2-ounce copper foil as an example, its cross-sectional area is greatly increased, allowing a larger current to pass through the unit area. According to the IPC-2152 standard, under specific temperature rise conditions, the current carrying capacity of copper foil is closely related to the cross-sectional area. Thick copper foil can effectively reduce current density, reduce circuit heating, and ensure stable circuit operation.
High heat dissipation performance is also an important feature of high-current PCB boards. When a large current passes through, the circuit will inevitably generate heat. If it cannot be dissipated in time, the component temperature will be too high, the performance will be reduced, or even damaged. High-current PCB boards often use high thermal conductivity materials, such as adding ceramic fillers to the substrate to improve thermal conductivity, or using materials with natural heat dissipation advantages such as aluminum substrates. At the same time, through the reasonable design of the heat dissipation structure, such as adding heat dissipation holes, large-area copper plating, etc., an efficient heat dissipation channel is constructed to quickly export heat and maintain a stable operating temperature of the equipment.
Design points
Line layout planning
The layout of high-current lines should follow the principle of being short and straight, reducing the bends in the current transmission path and reducing line resistance and inductance. For example, in a power module, the main current path from input to output should be as circuitous as possible to ensure smooth current flow. Lines of different current levels should be reasonably separated to prevent high-current lines from interfering with small signal lines and ensure signal integrity.
Copper foil thickness and line width calculation
It is very important to accurately calculate the copper foil thickness and line width. According to the current carrying requirements and allowable temperature rise of the circuit design, the appropriate parameters can be calculated using the relevant formula. If the design requires the temperature rise to not exceed 20°C and the current carrying capacity is 10A, the required copper foil thickness and line width can be obtained by combining the formula with the IPC-2152 standard data. In high-power motor drive circuits, the main circuit wiring often uses a copper foil thicker than 2 ounces, and the line width will be widened accordingly to reduce resistance and reduce heat.
Via design
As a channel connecting different layers of circuits, the design of vias is particularly critical in high-current PCB boards. The number of vias needs to be increased and reasonably distributed to form a dense via array to improve the current transmission capacity in the vertical direction. At the same time, ensure that the copper plating thickness of the vias is sufficient. Generally, the copper thickness of the vias is required to be ≥25μm to prevent the hole wall from burning under high current. For example, in a multi-layer high-current PCB board, a large number of well-coppered vias are densely arranged under the power components where heat is concentrated, so that the heat can be quickly transferred to other layers to enhance the heat dissipation effect.
Manufacturing process
Thick copper foil lamination
The first challenge facing high-current PCB manufacturing is the lamination of thick copper foil. Since the copper foil is thick, the temperature, pressure and time parameters need to be precisely controlled when laminating it with the substrate to ensure that the copper foil and the substrate are tightly combined without defects such as bubbles and delamination. Advanced vacuum lamination technology can extract air during the lamination process to ensure the lamination quality, control the uniformity of the dielectric thickness within a very small tolerance range, and improve the overall performance of the circuit board.
Deep hole plating
In order to make the vias have good conductivity, the deep hole electroplating process is essential. Traditional electroplating processes are difficult to ensure the uniformity and thickness of copper plating in deep holes of thick copper foil circuit boards. Deep hole electroplating technology optimizes the plating solution formula, current distribution method, etc. to achieve uniform copper plating on the hole wall, ensure that the hole copper thickness meets the high current carrying requirements, and avoid the via becoming a current transmission bottleneck.
Application areas
New energy vehicles
In the field of new energy vehicles, high-current PCBs are widely used in key components such as on-board chargers and DC-DC converters. OBCs are responsible for converting AC power into DC power to charge the battery. The current is large during operation, and the high current carrying and heat dissipation performance of high-current PCBs ensure charging efficiency and safety; DC-DC converters achieve power conversion at different voltage levels, and also rely on high-current PCBs to transmit current stably to ensure stable operation of the vehicle’s electrical system.
Industrial automation
High-power servo drives, inverters and other equipment in industrial automation need to precisely control the operation of motors, and high-current PCB boards provide them with stable power transmission. In servo drives, high-current PCB boards connect power modules and control circuits, efficiently transmit high currents, ensure that motors respond quickly to commands, achieve precise control, and meet the high-precision and high-reliability requirements of industrial production.
Power electronic equipment
Power electronic equipment such as photovoltaic inverters and UPS uninterruptible power supplies involve high-power power conversion and transmission. Photovoltaic inverters convert the direct current generated by solar panels into alternating current and feed it into the power grid. High-current PCB boards help them efficiently handle large currents and improve energy conversion efficiency. UPS provides emergency power to equipment when the city power is interrupted. High-current PCB boards ensure stable power supply under high loads and ensure continuous operation of key equipment.