四虎影成人精品a片-香蕉视频免费看-青青草青娱乐-国产喷水视频-中文字幕av网-一亲二脱三插-日韩中文字幕精品-超碰操-国产三级一区二区-亚洲天堂手机在线-亚洲国产成人综合-一区二区播放-国产精品最新-成人一卡二卡-国产淫视-都市激情一区-黄色一级图片-麻豆一级视频-国产成人免费看一级大黄-黄色a在线-男女日日-亚洲av综合色区无码一区-爱色av网站-亚洲网站在线看-国产一区资源

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.