For an LED display, a certain amount of heat will be generated during work, which will rapidly increase the internal temperature of the equipment. If the heat is not emitted in time, the equipment will continue to heat up, the device will fail due to overheating, and the reliability of electronic equipment will decline.

Therefore, it is very important to do a good cooling treatment for the circuit board.The heat dissipation of PCB is a very important link, so what are the heat dissipation methods of PCB?

Here are 10 ways to do it:

The first method:

Heat dissipation through PCB board itself is currently widely used PCB board is copper clad/epoxy glass cloth substrate or phenolic resin glass cloth substrate, there are a small number of paper-based copper clad board.

Although these substrates have excellent electrical properties and processing properties, they are poor in heat dissipation. As the heat dissipation path of high heating elements, it is almost impossible to transfer heat from the resin of PCB itself, but to dissipate heat from the surface of components to the surrounding air.

However, as electronic products have entered the era of miniaturization, high-density installation and thermal-heat assembly, it is not enough to only rely on the surface of components with very small surface area to dissipate heat.

At the same time, due to the extensive use of surface mounted components such as QFP and BGA, the heat generated by the components is transferred to PCB board in large quantities. Therefore, the best way to solve the heat dissipation is to improve the heat dissipation capacity of PCB itself that directly contacts with the heating elements, and conduct out or send out through PCB board.

PCB layout

A. Heat sensitive devices are placed in the cold air area.

B. Place the temperature detection device at the hottest position.

C, on the same piece of PCB device should as far as possible according to the calorific value of the size and degree of heat partition, calorific value is small or poor heat resistance devices (such as small signal transistor, small-scale integrated circuit, electrolytic capacitors, etc.) on the cooling airflow of the best () at the entrance, calorific value big or good heat resistance devices (such as power transistor, large scale integrated circuit, etc.) in the most downstream cooling airflow.

D. In the horizontal direction, high-power devices should be arranged as close as possible to the edge of the PCB, so as to shorten the heat transfer path;In the vertical direction, high-power devices are arranged as close as possible to the top of the PCB, so as to reduce the influence of these devices on the temperature of other devices.

E. The heat dissipation of printed boards in equipment mainly depends on air flow, so air flow path should be studied in the design, and devices or printed circuit boards should be reasonably configured.Air flow always tends to flow where resistance is low, so in the printed circuit board configuration device, to avoid leaving a large space in a certain area.The configuration of multiple printed circuit boards in the whole machine should also pay attention to the same problem.

F. Temperature-sensitive devices are best placed in the area with the lowest temperature (such as the bottom of the device), never put it directly above the heating device, and multiple devices are best placed in horizontal staggered layout.

G. The devices with the highest power consumption and maximum heating are arranged near the optimal position of heat dissipation.Do not place high-heating components on the corners and edges of a printed board unless a cooling device is arranged nearby.When designing power resistors, we should choose larger devices as far as possible, and adjust the layout of PCB so that there is enough heat dissipation space.

The second method:

Add heat sink and heat conducting plate for high heating devices when there are a few devices in PCB with a large amount of heat (less than 3), add heat sink or heat conducting tube on the heating device. When the temperature cannot fall, use the radiator with fan to enhance the heat dissipation effect.

When the amount of heating devices is large (more than 3), a large cooling cover (board) can be used. It is a special radiator customized according to the position and height of heating devices on the PCB board, or different positions of components can be cut out on a large flat radiator.

The heat sink is integrated on the component surface and contacts with each component to dissipate heat.However, due to the low and high consistency when the components are installed and welded, the heat dissipation effect is not good.Soft thermal phase change heat conduction pads are usually added on the surface of components to improve the heat dissipation effect.

Third method: for equipment with free-convection air cooling, it is best to arrange the integrated circuits (or other devices) in vertical or horizontal lengths. 

Fourth method:

Due to the poor thermal conductivity of the resin in the plate, and copper foil lines and holes are good conductors of heat, so improving the residual rate of copper foil and increasing the thermal conductivity hole are the main means of heat dissipation.

To evaluate the heat dissipation capacity of PCB, it is necessary to calculate the equivalent thermal conductivity (9 eq) of PCB insulation substrates for composite materials composed of various materials with different thermal conductivity coefficients

The fifth method:

On the same piece of PCB device should as far as possible according to the calorific value of the size and degree of heat partition is arranged, calorific value is small or poor heat resistance devices (such as small signal transistor, small-scale integrated circuit, electrolytic capacitors, etc.) on the cooling airflow of the best () at the entrance, calorific value big or good heat resistance devices (such as power transistor, large scale integrated circuit, etc.) in the most downstream cooling airflow.

The sixth method:

In the horizontal direction, high-power devices are arranged as close as possible to the edge of the PCB, so as to shorten the heat transfer path.In the vertical direction, high-power devices are arranged as close as possible to the top of the PCB, so as to reduce the influence of these devices on the temperature of other devices.

Seventh method:

The heat dissipation of the printed board in the equipment mainly depends on the air flow, so the air flow path should be studied in the design, and the device or printed circuit board should be reasonably configured.

Air flow always tends to flow where resistance is low, so in the printed circuit board configuration device, to avoid leaving a large space in a certain area.The configuration of multiple printed circuit boards in the whole machine should also pay attention to the same problem.

Eighth method:

Temperature sensitive devices are best placed in the lowest temperature area (such as the bottom of the device), never put it directly above the heating device, multiple devices are best in horizontal staggered layout.

Method 9:

The devices with the highest power consumption and maximum heating are arranged near the optimal position of heat dissipation.Do not place high-heating components on the corners and edges of a printed board unless a cooling device is arranged nearby.

When designing power resistors, we should choose larger devices as far as possible, and adjust the layout of PCB so that there is enough heat dissipation space.

Method 10:

Avoid concentration of hot spots on PCB, distribute power evenly on PCB board as much as possible, and keep uniform and consistent performance of PCB surface temperature.

It is often difficult to achieve strict uniform distribution in the design process, but we must avoid areas with too high power density, lest hot spots affect the normal work of the whole circuit.

If possible, it is necessary to conduct thermal efficiency analysis of printed circuits. For example, the thermal efficiency index analysis software module added in some professional PCB design software can help designers optimize circuit design