How to optimize the copper thickness and heat dissipation via design of high-power intelligent industrial control motherboard?
Publish Time: 2025-03-24
In the design of high-power intelligent industrial control motherboard, heat dissipation performance directly affects the stability and life of the system. As the power consumption of processors, FPGAs and power devices continues to increase, traditional heat dissipation solutions can no longer meet the needs. Copper thickness and heat dissipation vias are key factors in PCB thermal management and must be optimized in a coordinated manner to achieve efficient heat dissipation in a limited space.
Effect of copper thickness on heat dissipation performance
The copper foil thickness of PCB is usually measured in ounces (oz), and 1oz copper thickness is about 35μm. Increasing copper thickness can significantly improve the current carrying capacity and heat dissipation efficiency of the conductor because the thermal conductivity of copper is as high as 401 W/(m·K). For high-power industrial control motherboards, key areas (such as CPU power supply circuits and high-current routing) often use 2oz or even 3oz copper thickness to reduce on-resistance and Joule heat. However, the increase in copper thickness also brings challenges:
Increased processing difficulty: Thick copper PCBs are prone to side etching during etching, resulting in line width deviation, and special processes (such as differential etching) are required.
Increased cost: The proportion of copper materials increases, and more complex lamination control is required.
Impedance control difficulty: The characteristic impedance calculation of thick copper traces requires adjustment of the model, and high-frequency signals may be affected.
Therefore, the optimization of copper thickness needs to balance the heat dissipation requirements, manufacturing feasibility and signal integrity. Usually, a local thickening strategy is adopted, that is, thick copper is used in high-temperature areas, and the rest of the parts maintain standard thickness.
Design optimization of heat dissipation vias
Thermal vias are metallized holes that connect different layers of copper foil on the PCB, and transfer heat from the heating element to the heat dissipation layer or external heat sink through a vertical heat conduction path. Its design parameters (such as aperture, hole spacing, and filling material) directly affect the heat dissipation efficiency:
Aperture and hole spacing: Small aperture (such as 0.2mm) high-density vias can increase the thermal conductivity area, but uneven copper plating due to too thin hole walls must be avoided. An array layout is usually adopted, and the hole spacing is 2~3 times the aperture.
Filling material: Ordinary vias are hollow or filled with resin, while high-power scenarios can use conductive glue filling or copper plug holes to further improve thermal conductivity.
Connection method: Vias should be fully connected to the internal copper layer (such as power/ground plane) to avoid "thermal resistance bottleneck". For BGA packaged devices, via arrays are often arranged directly under the pad.
Coordinated design of copper thickness and heat dissipation vias
Simply increasing copper thickness or stacking vias cannot maximize the heat dissipation effect. The two need to work together systematically:
1. Thermal path planning: Thick copper layers are responsible for lateral heat diffusion, while via arrays build vertical heat channels. For example, thick copper traces are arranged under MOSFETs, and heat is transferred to the back copper layer or heat sink through vias.
2. Interlayer thermal balance: In multi-layer PCBs, heat is transferred from the inner layer to the outer layer through vias to avoid local heat accumulation. If a thick copper power layer is used, it can be used as a heat sink layer to form a three-dimensional heat dissipation network with vias.
3. Simulation-driven design: Use thermal simulation tools (such as ANSYS Icepak or Flotherm) to analyze temperature distribution and optimize copper thickness areas and via layout. For example, increase via density in high-temperature areas and adjust copper thickness to balance heat flow.
The heat dissipation optimization of high-power intelligent industrial control motherboard requires comprehensive copper thickness and via design, and builds an efficient thermal management system through the fine coordination of materials, layout and process. The synergistic strategy of local thick copper and high-density thermal conductive vias, combined with simulation verification, can achieve reliable heat dissipation in a limited space, laying the foundation for the long-term stable operation of industrial control equipment.
