Discussion on the configuration of heat dissipation hole in PCB design

As we all know, heat sink is a method to improve the heat dissipation effect of surface mounted components by using PCB board. In terms of structure, it is to set through holes on the PCB board. If it is a single-layer double-sided PCB board, it is to connect the surface of the PCB board with the copper foil on the back to increase the area and volume for heat dissipation, that is, to reduce the thermal resistance. If it is a multi-layer PCB board, it can be connected to the surface between the layers or the limited part of the connected layer, etc., the theme is the same.


The premise of surface mount components is to reduce thermal resistance by mounting to the PCB board (substrate). The thermal resistance depends on the copper foil area and thickness of the PCB acting as a radiator, as well as the thickness and material of the PCB. Basically, the heat dissipation effect is improved by increasing the area, increasing the thickness and improving the thermal conductivity. However, as the thickness of copper foil is generally limited by standard specifications, the thickness can not be increased blindly. In addition, nowadays miniaturization has become a basic requirement, not just because you want the area of THE PCB, and in fact, the thickness of copper foil is not thick, so when it exceeds a certain area, it will not be able to obtain the heat dissipation effect corresponding to the area.

One of the solutions to these problems is the heat sink. To use the heat sink effectively, it is important to position the heat sink close to the heating element, such as directly under the component. As shown in the figure below, it can be seen that it is a good method to make use of the heat balance effect to connect the location with large temperature difference.

Discussion on the configuration of heat dissipation hole in PCB design

Configuration of heat dissipation holes

The following describes a specific layout example. Below is an example of the layout and dimensions of the heat sink hole for HTSOP-J8, a rear exposed heat sink package.

In order to improve the thermal conductivity of the heat dissipation hole, it is recommended to use a small hole with an inner diameter of about 0.3mm that can be filled by electroplating. It is important to note that solder creep may occur during reflow processing if the aperture is too large.

The heat dissipation holes are about 1.2mm apart, and are arranged directly under the heat sink on the back of the package. If only the back heat sink is not enough to heat, you can also configure heat dissipation holes around the IC. The point of configuration in this case is to configure as close to the IC as possible.

Discussion on the configuration of heat dissipation hole in PCB design

As for the configuration and size of the cooling hole, each company has its own technical know-how, in some cases may have been standardized, therefore, please refer to the above content on the basis of specific discussion, in order to obtain better results.

Key points:

Heat dissipation hole is a way of heat dissipation through the channel (through hole) of PCB board.

The cooling hole should be configured directly below the heating element or as close to the heating element as possible.