PCBgogo

In the production and testing of electronic devices, abnormal overheating of PCBA (Printed Circuit Board Assembly) is a common yet challenging issue. Excessive temperatures can not only affect the performance of the equipment but also lead to component damage and even equipment failure. Therefore, it is crucial to quickly identify the causes of overheating and take effective measures to resolve them. This article will explore the approaches and solutions for diagnosing PCBA overheating from three aspects: design, materials, and testing.

Common Causes of PCBA Overheating

Design Flaws

Design defects in the PCB stage are significant causes of overheating. For example:

• Improper Layout: High heat-generating components are too concentrated, making it difficult for heat to dissipate.

• Routing Issues: Insufficient copper foil area or too narrow routing leads to low heat conduction efficiency.

• Inadequate Cooling Design: No sufficient cooling space is reserved or no effective cooling channels are designed.

Improper Material Selection

The thermal conductivity of the PCB substrate directly affects the cooling effect. If materials with high thermal resistance are selected, heat cannot be quickly transferred to the external environment, leading to excessive local temperature rise.

Component Issues

• Power Device Heating: High-power components generate a large amount of heat during operation. Without cooling devices, local high temperatures can easily occur.

• Component Failure: Damaged capacitors or chips can lead to abnormal current, further exacerbating heating.

Manufacturing Process Issues

• Poor Soldering: Cold soldering or bridging can lead to abnormal current distribution, causing local overheating.

• Residue Impact: Residues of flux or solder paste can corrode the circuit, causing leakage or short circuits.

External Environmental Factors

• High-Temperature Environment: Operating equipment under extreme temperature conditions increases cooling pressure.

• Insufficient Ventilation: Poor air circulation inside the equipment leads to heat accumulation.

Steps and Methods for Diagnosing Overheating

Visual Inspection

First, visually inspect the PCBA for obvious physical damage, such as burnt, cracked, or bulging capacitors. Also, check for cold soldering or short circuits at the solder joints.

Thermal Imaging Camera Detection

Use a thermal imaging camera to scan the surface of the PCBA to quickly locate areas with abnormal temperatures. This method is intuitive and efficient, especially for identifying hot spots on complex circuit boards.

Heating Analysis Method

Connect the PCBA to a DC power supply, set it to current-limiting mode, gradually adjust the current, and observe the heating areas.

Confirm the specific hot spots through touch or thermal imaging to determine whether the problem is caused by a short circuit or component failure.

Circuit Testing

Use a multimeter to test the voltage and resistance at key nodes to determine if there are any abnormalities in the power supply or load.

Employ boundary scan testing technology to check the status of chip pins and locate chip-level failures.

Data Analysis and Recording

Record the overheating phenomena, test data, and troubleshooting process, establish a fault database, analyze common problem patterns, and provide a basis for subsequent optimization.

Effective Measures to Resolve PCBA Overheating

Optimize Design

• Rational Layout: Distribute heat-generating components to avoid heat concentration.

• Increase Copper Foil Area: Add copper foil area in power and ground layers to improve heat conduction efficiency.

• Design Cooling Channels: Enhance air circulation and accelerate cooling through ventilation holes or air duct structures.

Select Appropriate Cooling Materials

• Thermal Grease and Thermal Pads: Fill the gaps between heat-generating components and heat sinks to improve heat transfer efficiency.

• Heat Sinks and Graphite Sheets: Increase cooling area and quickly conduct heat, suitable for high heat density areas.

Improve Manufacturing Processes

• Optimize Soldering Processes: Ensure solder joint quality to avoid cold soldering or bridging.

• Clean Residues: Timely remove flux and solder paste residues to prevent corrosion and short circuits.

Enhance Cooling Testing and Monitoring

Conduct thermal simulations during the design phase to predict hot spots and use thermal imaging cameras to monitor in real-time during production to ensure cooling effects meet requirements.

Conclusion

Diagnosing and resolving PCBA overheating requires a comprehensive approach involving design, materials, manufacturing, and testing. By adopting rational design, high-quality material selection, and scientific testing methods, the risk of overheating can be effectively reduced, enhancing the stability and reliability of equipment. It is hoped that the experiences shared in this article can provide a reference for relevant practitioners and help solve cooling challenges in actual production.