Applications for high-power electronic products are many, ranging from consumer items to automotive and medical equipment. Industrial manufacturing is a primary use of high-power electronics. A manufacturing facility that operates several motors and other heavy gear has enormous power requirements. With such high-power electronics, printed circuit boards (PCB) with hardware board design are supposed to handle overheating and user safety issues.
Creating circuits with high current and high voltage presents a number of difficult issues. If a high-speed or mixed-signal circuit is included in the design, the difficulties will increase. Under such circumstances, PCB manufacture might be a little challenging. Therefore, selecting the right substrate material, placing components correctly, strategically designing the board layout and stack-up, and adhering to regulatory requirements are all necessary to create an effective, high-power PCB. Using simulation tools, the circuit’s power distribution and heat dissipation must also be assessed.
Creating circuits with high current and high voltage presents a number of difficult issues. See this page for further PCB design advice.
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PCB Design Guidelines
Typically, excess heat is produced by high-power electronic components and high-current carrying lines. To swiftly transmit the excess heat, a high thermal conductivity PCB material should be used. The rate at which heat is transmitted from a thermal source toward colder PCB sections is known as thermal conductivity, or K. A PCB substrate such as FR4 contains a dielectric substance with an extremely low K value of around 0.25 W/m-K. Ceramics are the ideal substrate material for high-power systems since they have better thermal conductivity.
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PCB Selection of Substrates
A multi-layer PCB’s substrates and laminates need to have the same coefficient of thermal expansion (CTE) throughout all of its layers. Extreme heat-induced temperature variations in the board will cause the laminates with comparable CTE to expand or contract evenly, preventing the board from mechanically deforming.
The pcb hardware design for the substrate used for high-power applications should have a glass transition and a Tg value greater than the electronic product’s maximum operating temperature. A 20 °C buffer at least is advised. For instance, the Tg of the PCB substrate should be 190 °C or more if the product operates at 170 °C. Substrates made of copper and aluminum are recommended for these kinds of high working temperatures.
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Component Arrangement
Due to their high heat output, high-power components such as power amplifiers and voltage converters have to be prioritized. To reduce their trace lengths, it is also advised that the components that go with them be grouped together. High pin count digital integrated circuits (FPGAs, CPUs, etc.) generate heat and are best positioned in the middle of the board to provide even thermal dispersion. It is best to keep sensitive circuits away from components that produce heat.
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Design of GND Plane and PCB Stackup
Enough power and ground planes should be included in the PCB stack-up to separate sensitive signals from power components that produce noise that are mounted on exterior surfaces. It is better if the power components have their own ground. In order to prevent ground bounce caused by the simultaneous switching of active components, decoupling capacitors must be added in close proximity to the IC power pins. l.
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Design of PCB Layout
It is advised to choose the trace width for high-current carrying pathways in accordance with IPC -2221 guidelines. A trace thickness of 35-105 µm is necessary for current values more than or equal to 10 A. For high-current lines, wider traces or thicker copper are recommended to prevent heat dissipation from PCB power losses.
In high-power circuits, control over the power traces’ route is crucial during layout design. Software simulations must be used to examine this since it will control the board’s heat production. When designing a high-power PCB layout, take into account the airflow for heat dissipation, the power flow sequence, and the ambient temperature of the circuit during operation.
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Advice on Thermal Management
Several thermal management strategies are used in the design of the high-power printed circuit board. In order to dissipate heat from the active components, fans or heatsinks are required. Heatsinks are attached to active components by thermal pads and pastes, which also serve as heat-capturing devices to release excess heat into the surrounding air. Additional cooling methods, such as fan circuits, are available for high pin density integrated circuits (ICs) such as CPUs and FPGAs.
The PCBs become heated by the high-current traces. When the solder mask is removed from certain traces, the copper material is visible. This copper thickness may then be increased by adding more solder, which will lower the heat production on those lines. To prevent corrosion on exposed copper traces and pads in a hostile working environment, apply a silver-plating finish to the product.
To improve the amount of heat dissipation to the environment, large ground planes are linked to the top and bottom layers of the PCB’s exterior surfaces. Heat may be transferred from a hotspot to other PCB layers via thermal vias. A high-power circuit’s many constituents are environment-sensitive. The external atmosphere’s temperature stability affects their performance. Optimizing the performance of the board requires providing heat insulation to these delicate components.
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Design for EMI Compliance
Radiation-producing parts of high-power circuits include relays, amplifiers, switches, and so on. When developing a PCB for high-power applications, it is essential to comply with the FCC regulations. EMI problems may be greatly avoided by placing the board in an enclosure and shielding it.
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Design for High Voltage
To avoid electrical arcing in high-voltage circuits, sufficient spacing between metal surfaces is advised. The board and its parts may be harmed by high-voltage arcing. It’s crucial to adhere to standards, which specify the clearance and creepage criteria for high-voltage devices.
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In summary
User safety and overheating are problems when designing embedded system for high-power electronics. Build a safe PCB for a high-power electrical gadget by using the aforementioned advice. You may include an integrated temperature sensor to notify the user and improve product safety. In order to protect your product from potential short circuit risks, include a fuse at the high current output.