PCB Heat Dissipation Hole Configuration
As we all know, heat dissipation holes are a method of using PCB to improve the heat dissipation effect of surface mount components. In the structure, a through hole is set on the PCB board. If it is a single-layer double-sided PCB, the copper foil on the surface and on the back surface are connected to increase the area and volume for heat dissipation. This is how to reduce the thermal resistance. If it is a multi-layer PCB, it can connect the surfaces between the layers or define a part of the connection layer, etc. Their purpose is the same.
The premise of surface mount components is to reduce thermal resistance by mounting on a PCB (substrate). The thermal resistance depends on the area and thickness of the copper foil on the PCB that acts as a heat sink and the thickness and material of the PCB. Basically, the heat dissipation effect is improved by increasing the area, the thickness and the thermal conductivity. However, since the thickness of copper foil is generally limited by standard specifications, the thickness cannot be increased blindly. In addition, miniaturization has become a basic requirement now, we can't take up the area just because we want the PCB area. In fact the thickness of the copper foil is not too thick. Therefore, when a certain area is exceeded, the heat dissipation effect corresponding to the area cannot be obtained.
One of the countermeasures for these issues is the heat dissipation hole. To effectively use the heat dissipation holes, it is important to arrange the heat dissipation holes close to the heating element, for example, directly below the components. It is a good method to connect a location with a large temperature difference.
In order to improve the thermal conductivity of the heat dissipation hole, it is recommended to use a small diameter through hole with an inner diameter of about 0.3mm that can be filled by plating. It should be noted that if the hole diameter is too large, the problem of solder creepage may occur in the reflow process.
The intervals between the heat dissipation holes are about 1.2mm, and they are arranged directly under the heat sink on the back of the package. If only the bottom of the rear heat sink is not sufficient for heat dissipation, heat dissipation holes can also be arranged around the IC. The configuration point in this case is to configure as close to the IC as possible.
Regarding the configuration and size of heat dissipation holes, each company has its own technical know-how, and in some cases may have been standardized, so please refer to the above content for specific discussion to obtain better results.
Key points of heat dissipation hole configuration
・ The heat dissipation hole is a method of dissipating heat by using a channel (via) that passes through the PCB to transfer heat to the back.
・ The heat dissipation holes should be placed directly under the heating element or placed close to the heating element.
