What are the aging testing methods for PCBs?

　　The aging test of PCB (printed circuit board) is to evaluate its performance and reliability during long-term use. Here are some common aging testing methods:

　　1. High temperature aging test:

　　Constant temperature aging: Place the PCB in a high temperature environment, usually between 70 ° C and 150 ° C, for a period of time, and observe its performance changes under high temperature conditions.

　　Temperature cycle: Cycle between high and low temperatures, simulate temperature changes in actual usage environments, and evaluate the thermal stability of PCBs.

　　2. Damp heat aging test:

　　Constant humidity and heat: Place the PCB in a high-temperature and high humidity environment, typically at 85 ° C and 85% relative humidity, to test its performance changes under humid and heat conditions.

　　Damp heat cycle: Cycle under different humidity and temperature conditions to evaluate the moisture resistance of PCB.

　　3. Voltage stress test:

　　Overvoltage test: Apply a voltage higher than the rated voltage to test the performance and reliability of the PCB under overvoltage conditions.

　　Voltage fluctuation test: Under voltage fluctuation conditions, test the stability and tolerance of the PCB.

　　4. Power aging test:

　　Full load aging: Load the maximum operating current on the PCB and test its performance and temperature changes under full load conditions.

　　Intermittent aging: Cycle under different load conditions, simulate the load changes in actual use, and evaluate the durability of PCB.

　　5. Mechanical stress testing:

　　Vibration testing: Place the PCB on a vibration table, simulate the vibration environment during transportation and use, and evaluate its anti vibration performance.

　　Impact testing: Apply instantaneous impact force to test the structural integrity of the PCB under impact conditions.

　　6. Chemical aging test:

　　Gas corrosion test: Place the PCB in an environment containing corrosive gases and test its performance changes under chemical corrosion conditions.

　　Salt spray test: Place the PCB in a salt spray environment to test its corrosion resistance under salt spray conditions.

　　7. Optical inspection:

　　Microscopic examination: Use an optical microscope or scanning electron microscope to examine the microstructure changes of PCB, such as solder joint cracks, copper foil peeling, etc.

　　Infrared thermal imaging detection: Use an infrared thermal imager to detect the temperature distribution of PCB, identify overheated areas, and evaluate their thermal stability.

　　8. Electrical performance testing:

　　Resistance test: Measure the resistance changes of PCB and evaluate the changes in its conductivity performance.

　　Insulation test: Measure the insulation resistance and dielectric constant of PCB to evaluate the changes in its insulation performance.

　　Through the above aging testing methods, the performance and reliability of PCBs under different environmental and stress conditions can be comprehensively evaluated, helping to