What are the main factors of PCB solder joint failure analysis?

Date：2022-12-13 16:39:06 Views：733

In the actual processing process, PCBA solder joint failure is also encountered. On the one hand, solder joint failure comes from welding failures in production and assembly, such as solder bridging, faulty welding, Manhattan phenomenon, etc; On the other hand, under service conditions, when the ambient temperature changes, due to the difference in thermal expansion coefficient between components and substrate materials, thermal stress is generated in the solder joint. Periodic changes in stress will cause fatigue damage to the solder joint. At the same time, compared with the temperature of the service environment, the melting point of SnPb solder is low. With the time going on, obvious viscosity behavior will occur, leading to variable damage to the solder joint. It is necessary to analyze and find out the cause to avoid the solder joint failure again. So today, let's introduce the main factors of PCB solder joint failure analysis.

Main reasons for PCBA processing solder joint failure:

1. Poor component pins: coating, pollution, oxidation, coplanar.

2. Poor PCB pad: coating, pollution, oxidation, warping.

3. Solder quality defects: composition, impurities not up to standard, oxidation.

4. Flux quality defects: low flux, high corrosion, low SIR.

5. Process parameter control defects: design, control and equipment.

6. Defects of other auxiliary materials: adhesives and cleaning agents.

Methods for increasing the stability of PCBA solder joints:

The stability experiment of PCBA solder joint includes stability experiment and analysis. On the one hand, its purpose is to evaluate and identify the stability level of PCBA integrated circuit devices and provide parameters for the stability design of the whole machine.

On the other hand, it is necessary to improve the stability of solder joints during PCBA processing. Therefore, it is necessary to analyze the failed products, find out the failure mode and analyze the failure cause. The purpose is to modify and improve the design process, structural parameters and welding process, and improve the finished product rate of PCBA. The failure mode of PCBA solder joint is the basis of predicting its cycle life and establishing its mathematical model.

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