There are three primary sources of heat in a PCB circuit board:
(1) Heating of electronic components;
(2) Heating of the PCB circuit board itself;
(3) Heat from external sources.
Among these, electronic components are the main heat source due to their high calorific value, followed by the PCB circuit board itself. External heat depends on the overall thermal design of the system and is not considered here. The goal of thermal design is to implement appropriate measures to significantly reduce the temperature of both electronic components and the PCB circuit board, ensuring that the system operates within a suitable temperature range.
Consider the following aspects:
1. Heat dissipation through the PCB circuit board itself. Currently, commonly used PCB materials include copper-clad/epoxy glass cloth substrates or phenolic resin glass cloth substrates, with a small number of paper-based copper-clad boards also in use. Although these substrates offer excellent electrical properties and processing capabilities, their heat dissipation is inadequate. For high-heat electronic components, relying on the PCB resin for heat conduction is impractical; instead, heat must be dissipated from the surface of the electronic components into the surrounding air.
1. As time progresses, smart electronic products have entered an era of miniaturized components, high-density mounting, and high-heat assembly. Relying solely on the small surface area of electronic components to dissipate heat is insufficient. Additionally, with the extensive use of surface-mounted components like QFP and BGA, substantial heat generated by these components is transferred to the PCB board. Thus, the most effective way to manage heat dissipation is to increase the PCB area in direct contact with the heating components, allowing the heat to be conducted or emitted through the PCB.
2. For high heat-generating components, adding a radiator or heat conduction board can help. When a few components on the PCB generate significant heat (less than 3), a heat sink or heat pipe can be added. If the temperature remains high, a fan or radiator can enhance heat dissipation. For numerous heating components (more than 3), a large heat dissipation cover, customized according to the position and height of these components on the PCB or a large flat radiator with cutouts, should be used. The heat dissipation cover is designed to be integrally buckled onto the surface of the components, but due to inconsistent heights during assembly and soldering, the effect may be suboptimal. A soft thermal phase change pad can improve this effect.
3. Choose a suitable wiring design to enhance heat dissipation. Since the resin in the plate has poor thermal conductivity, and copper foil lines and holes are effective heat conductors, increasing the copper foil area and adding heat conduction holes are key methods for improving heat dissipation.
4. Minimize thermal resistance between high heat-dissipating components and the substrate. To meet thermal characteristics more effectively, thermal conductive materials, such as a layer of thermally conductive silicone, can be applied to the chip’s bottom surface. Ensuring a sufficient contact area helps with effective heat dissipation.
5. Arrange high-power devices as close to the edge of the printed board as possible in the horizontal direction to shorten the heat transfer path. In the vertical direction, position these devices closer to the top of the board to reduce the impact on the temperature of other components.
6. The heat dissipation of the printed board primarily relies on airflow. Therefore, study airflow paths during design and configure the device or printed circuit board accordingly. Air tends to flow through areas of lower resistance, so avoid large air gaps in certain regions. When configuring multiple PCBs in the whole system, this consideration is equally important.
7. Place temperature-sensitive devices in the coolest areas (such as the bottom of the device) and avoid placing them directly above heating components. Stagger devices on the horizontal plane to optimize temperature management.
8. Avoid concentrating heat spots on the PCB. Distribute power evenly across the PCB to maintain uniform surface temperature performance. Although achieving strict uniformity is challenging, avoid areas with high power density to prevent hot spots from affecting the circuit’s normal operation.
(1) Heating of electronic components;
(2) Heating of the PCB circuit board itself;
(3) Heat from external sources.
Among these, electronic components are the main heat source due to their high calorific value, followed by the PCB circuit board itself. External heat depends on the overall thermal design of the system and is not considered here. The goal of thermal design is to implement appropriate measures to significantly reduce the temperature of both electronic components and the PCB circuit board, ensuring that the system operates within a suitable temperature range.
Consider the following aspects:
1. Heat dissipation through the PCB circuit board itself. Currently, commonly used PCB materials include copper-clad/epoxy glass cloth substrates or phenolic resin glass cloth substrates, with a small number of paper-based copper-clad boards also in use. Although these substrates offer excellent electrical properties and processing capabilities, their heat dissipation is inadequate. For high-heat electronic components, relying on the PCB resin for heat conduction is impractical; instead, heat must be dissipated from the surface of the electronic components into the surrounding air.
1. As time progresses, smart electronic products have entered an era of miniaturized components, high-density mounting, and high-heat assembly. Relying solely on the small surface area of electronic components to dissipate heat is insufficient. Additionally, with the extensive use of surface-mounted components like QFP and BGA, substantial heat generated by these components is transferred to the PCB board. Thus, the most effective way to manage heat dissipation is to increase the PCB area in direct contact with the heating components, allowing the heat to be conducted or emitted through the PCB.
2. For high heat-generating components, adding a radiator or heat conduction board can help. When a few components on the PCB generate significant heat (less than 3), a heat sink or heat pipe can be added. If the temperature remains high, a fan or radiator can enhance heat dissipation. For numerous heating components (more than 3), a large heat dissipation cover, customized according to the position and height of these components on the PCB or a large flat radiator with cutouts, should be used. The heat dissipation cover is designed to be integrally buckled onto the surface of the components, but due to inconsistent heights during assembly and soldering, the effect may be suboptimal. A soft thermal phase change pad can improve this effect.
3. Choose a suitable wiring design to enhance heat dissipation. Since the resin in the plate has poor thermal conductivity, and copper foil lines and holes are effective heat conductors, increasing the copper foil area and adding heat conduction holes are key methods for improving heat dissipation.
4. Minimize thermal resistance between high heat-dissipating components and the substrate. To meet thermal characteristics more effectively, thermal conductive materials, such as a layer of thermally conductive silicone, can be applied to the chip’s bottom surface. Ensuring a sufficient contact area helps with effective heat dissipation.
5. Arrange high-power devices as close to the edge of the printed board as possible in the horizontal direction to shorten the heat transfer path. In the vertical direction, position these devices closer to the top of the board to reduce the impact on the temperature of other components.
6. The heat dissipation of the printed board primarily relies on airflow. Therefore, study airflow paths during design and configure the device or printed circuit board accordingly. Air tends to flow through areas of lower resistance, so avoid large air gaps in certain regions. When configuring multiple PCBs in the whole system, this consideration is equally important.
7. Place temperature-sensitive devices in the coolest areas (such as the bottom of the device) and avoid placing them directly above heating components. Stagger devices on the horizontal plane to optimize temperature management.
8. Avoid concentrating heat spots on the PCB. Distribute power evenly across the PCB to maintain uniform surface temperature performance. Although achieving strict uniformity is challenging, avoid areas with high power density to prevent hot spots from affecting the circuit’s normal operation.
