10 Effective PCB Heat Dissipation Techniques to Enhance Electronic Device Reliability

In the modern field of electronics, as device sizes continue to shrink and performance keeps improving, thermal management issues have become increasingly prominent and cannot be ignored. Just as a wise person once said, "Technological advancement often comes hand in hand with the release of heat." The heat generated by electronic devices during operation, if not properly dealt with and dissipated, can be like an imperceptible threat, quietly endangering the stability and lifespan of the equipment. In this ever-changing digital world, mastering key techniques for PCB (Printed Circuit Board) cooling is not only a guarantee for enhancing the reliability of electronic devices but also an essential path toward leading the forefront of technology.Electronic devices generate a certain amount of heat during operation, causing the internal temperature of the device to rise rapidly. If this heat is not promptly dissipated, the device will continue to heat up, leading to component failure due to overheating, thereby reducing the reliability and performance of the electronic device. Therefore, it is crucial to effectively manage the heat dissipation of the circuit board. Heat dissipation for PCBs plays a vital role, so let's discuss some techniques for PCB heat dissipation. The widely used PCB materials for heat dissipation include copper-clad epoxy glass cloth substrate or phenolic resin glass cloth substrate, with a small number also utilizing paper-based copper-clad boards. While these substrates possess excellent electrical and processing properties, their heat dissipation is poor. As a cooling method for high-heat-generating components, it is nearly impossible to rely on thermal conduction through the PCB resin itself, but rather, heat is dissipated from the surface of the components into the surrounding air. But with the advent of electronic products entering the era of miniaturized components, high-density assembly, and high heat generation, relying solely on the small surface area of components for heat dissipation is far from sufficient. Simultaneously, due to the widespread use of surface-mounted components such as QFP and BGA, the heat generated by electronic components is extensively transferred to the PCB. Therefore, the most effective method to address heat dissipation is to enhance the PCB's inherent heat dissipation capability in direct contact with the heat-generating components, allowing for conduction or dissipation of heat through the PCB.

PCB layout and component placement

Cold air zones and thermosensitive components

Placing thermal sensors in the cold air zone ensures they receive better air circulation.

Temperature detection device

The temperature detection device is placed at the hottest location.

Partition Arrangement

Components on the same printed circuit board should be partitioned according to their heat generation and heat dissipation levels as much as possible. Components with lower heat generation or poor heat resistance (such as small signal transistors, small-scale integrated circuits, electrolytic capacitors, etc.) should be placed at the upstream of the cooling airflow (inlet), while components with higher heat generation or better heat resistance (such as power transistors, large-scale integrated circuits, etc.) should be placed at the downstream of the cooling airflow.

Vertical and Horizontal Layout.

In the horizontal direction, high-power devices should be placed closer to the edge of the printed circuit board to shorten the heat transfer path. In the vertical direction, high-power devices should be positioned above the printed circuit board to minimize their impact on the temperature of other devices during operation. The heat dissipation within the equipment's printed circuit board primarily relies on airflow. Therefore, during the design phase, it is important to study the airflow pathways and arrange components or the printed circuit board appropriately.

Temperature-sensitive sensor component location

Air tends to flow towards areas with lower resistance when in motion. Therefore, when arranging components on a printed circuit board, it is important to avoid leaving large open spaces in a particular area. The placement of components across multiple PCBs within a system should also consider this principle. Devices that are sensitive to temperature should ideally be positioned in the coolest regions, such as the bottom of the equipment. It is crucial to avoid placing them directly above heat-emitting components. When arranging multiple devices, it is advisable to employ a staggered layout on a horizontal plane.

High-power devices

Place the devices with the highest power consumption and greatest heat generation near the optimal cooling locations. Avoid placing high-heat generating devices in the corners and edges of the printed circuit board unless there is a cooling apparatus arranged nearby.

Radiator and Heat Conduction Plate

Small-scale heating devices

When designing power resistors, it is advisable to select larger devices and ensure sufficient heat dissipation space when adjusting the printed circuit board layout. For high-heat generating components, heat sinks and heat-conductive plates can be added. When there are only a few components generating significant heat (less than 3), heat sinks or heat pipes can be attached to the heating components. If the temperature cannot be lowered sufficiently, a fan-equipped heat sink can be employed to enhance heat dissipation.

Large-Scale Heat Dissipation Components

When there are a significant number of heat-generating components (more than 3), a larger heat dissipation enclosure (plate) can be employed. This specialized heat sink is customized based on the positions and heights of the heat-generating components on the PCB board, or it can involve creating varying component height locations on a large flat heat sink. The heat dissipation enclosure is securely attached to the component surface, contacting each individual component for effective heat dissipation.

Thermal Phase Change Conductive Pad

However, due to poor consistency in component height during soldering, the heat dissipation effect is not optimal. It is common practice to enhance heat dissipation by applying a flexible thermal phase change conductive pad onto the component surface.

Circuit design and routing layout

For equipment utilizing free convection air cooling, it is preferable to arrange integrated circuits (or other components) in a vertical orientation or a horizontal orientation. To achieve efficient heat dissipation through a well-designed routing scheme, enhancing copper trace retention and incorporating thermal vias are the primary methods. Due to the poor thermal conductivity of resin within the board material, copper traces and vias serve as effective conductors of heat. Evaluating a PCB's heat dissipation capability necessitates the calculation of the equivalent thermal conductivity of the composite material, which comprises various materials with differing thermal conductivities, used in the PCB's insulating substrate. Components on the same printed circuit board should be arranged into zones based on their heat generation and heat dissipation capabilities. Components with lower heat generation or lower heat resistance, such as small-signal transistors, small-scale integrated circuits, and electrolytic capacitors, should be placed upstream of the cooling airflow (inlet). Components with higher heat generation or better heat resistance, such as power transistors and large-scale integrated circuits, should be placed downstream of the cooling airflow. In the horizontal direction, high-power devices should be arranged closer to the edge of the printed circuit board to shorten the heat transfer path. In the vertical direction, high-power devices should be positioned above on the printed circuit board to minimize their impact on the temperatures of other components. The heat dissipation of the printed circuit board inside the device primarily relies on the flow of air. Therefore, during the design phase, it is crucial to study the airflow pathways and strategically position components or the printed circuit board. Air tends to flow towards areas of lower resistance when in motion, so when placing components on a printed circuit board, it is important to avoid leaving large voids in a particular area. The configuration of multiple printed circuit boards within the assembly should also take into consideration the same issues. It is advisable to place temperature-sensitive components in the lowest temperature zone (such as the bottom of the device). Avoid placing them directly above heat-emitting components. When dealing with multiple components, it is preferable to arrange them in an interleaved layout on a horizontal plane. Place the components with the highest power consumption and maximum heat generation near the optimal heat dissipation location. Avoid placing high-heat generating components in the corners and edges of the printed circuit board unless there are heat dissipation devices arranged nearby. When designing power resistors, choose larger components whenever possible, and ensure sufficient heat dissipation space when adjusting the printed circuit board layout. Minimize the concentration of hotspots on the PCB and distribute the power as evenly as possible across the PCB to maintain uniform and consistent surface temperature performance. Achieving a strict uniform distribution is often challenging in the design process, but it is essential to avoid regions with excessively high-power density. This precaution is taken to prevent the occurrence of hotspots that could adversely affect the normal operation of the circuit. Performing thermal energy analysis for printed circuits is essential if conditions allow for it. The inclusion of thermal energy index analysis software modules in some professional PCB design software nowadays can assist design engineers in optimizing circuit design. In the modern high-tech field, the significance of PCB thermal management techniques is becoming increasingly prominent. Just as a great architect must consider the stability of a skyscraper when designing it, electronic engineers must also focus on the flow and dispersion of heat when designing circuit boards. Through proper layout, selecting appropriate heat-dissipating materials, and making full use of modern design tools, we can create a perfect "temperature control system" within electronic devices, allowing each component to operate efficiently at suitable temperatures and emit a dazzling brilliance. Just as human civilization thrives through innovation, electronic technology also continues to evolve through thermal management. Let us unite closely on the stage of technology, striving unremittingly to create a more intelligent, efficient, and reliable electronic world!

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