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Common problems are easy to occur in the process of circuit board operation, personnel circulation, equipment gravity and other factors, through hole component insertion, In-circuit testing, single board segmentation, circuit board installation, circuit board point riveting, screw installation and other processes. This kind of crack generally originates from the upper and lower metal bonding ends of the device, and spreads to the inside of the device at 45 ℃. This type of defect is also the most common type of defect.

1. Mechanical stress factors:

(1) Test probe causing PCB bending

(2) The Influence of PCB Bending and Fracture on PCB

(3) The installation of the suction nozzle (the pressure of the suction nozzle is too high, the distance between the pressures is too deep) and the impact caused by the fixation of the middle claw.

(4) Excessive tin (such as a regular liner at one end).

2. Principle of mechanical stress crack generation:

Chip capacitors are a brittle material. If the PCB board is bent, it will be subjected to a certain amount of mechanical stress impact. When the stress exceeds the strength of ceramic bodies with patch capacitors, bending cracks will occur. Therefore, the cracks generated by this bending only appear after welding.

I have learned the precautions to pay attention to when using SMD capacitors. Although SMD capacitors are small, the compression energy should not be too large. We should pay attention to the necessity of protective measures.