1. Factors Influencing Temperature Rise in Printed Circuit Boards
The primary cause of temperature rise in a PCB is the power consumption of the circuit components. All electronic devices consume power to varying degrees, and the amount of heat generated correlates with the level of power consumption.
Two key phenomena contributing to temperature rise in PCBs:
(1) Local temperature rise or large-area temperature rise;
(2) Short-term temperature rise or long-term temperature rise.
When analyzing PCB thermal power consumption, it is typically examined from the following perspectives.
1. **Electrical Power Consumption**
(1) Analyze power consumption per unit area;
(2) Analyze the distribution of power consumption across the PCB.
2. **PCB Structure**
(1) PCB size;
(2) Material of the PCB.
3. **PCB Installation**
(1) Installation method (e.g., vertical or horizontal installation);
(2) Sealing conditions and the distance from the casing.
4. **Thermal Radiation**
(1) Emissivity of the PCB surface;
(2) Temperature difference between the PCB and adjacent surfaces, and their absolute temperatures.
5. **Heat Conduction**
(1) Installation of heat sinks;
(2) Heat conduction through other structural parts of the installation.
6. **Thermal Convection**
(1) Natural convection;
(2) Forced cooling convection.
Analyzing these factors is an effective approach to addressing temperature rise in PCBs. These factors are often interrelated and dependent on one another within a product or system. Most of these factors should be assessed based on the specific circumstances, as only under particular conditions can parameters such as temperature rise and power consumption be accurately calculated or estimated.
**2. PCB Heat Dissipation Methods**
1. **High Heat-Generating Components with Heat Sink and Thermal Pad**
When a few components on the PCB generate a significant amount of heat (typically fewer than 3), a heat sink or heat pipe can be added to the heat-generating components. If the temperature cannot be sufficiently reduced, a heat sink with a fan may be used to enhance heat dissipation.
For scenarios with more than 3 heat-generating components, a larger heat dissipation cover or plate can be used. This cover is a custom-designed heat sink that matches the positions and heights of the components on the PCB, or a large, flat heat sink that is cut to accommodate various component heights. The heat dissipation cover is directly mounted onto the components, making contact with each one to dissipate heat. However, heat dissipation effectiveness may be compromised if there is poor height consistency during assembly and soldering of components. Typically, a soft thermal phase-change material is added to the component surfaces to improve the heat dissipation performance.
