SMT 缺陷.pdf - 第12页

21 Cold solder/ Cold solder/ 冷焊冷焊 •Incomplete reflow of solder paste. 焊锡回流不完全

Non

Wetting, Dewetting/

虚焊，半

虚焊，半润湿

1. Poor solderability of component or pad./元件或焊盘可焊性太低

Root cause: a) Old date component or PCB. /陈旧元件或PCB板

b) Contamination or oxidation on component or PCB.

元件或焊盘污染或氧化

Action: Purge the material for further disposition. /清除来料

2. The paste out of its life time: /锡膏超出有效期

Scrap the lot paste and replace it with fresh one

报废有问题的锡膏更换新锡膏

Cold solder/

冷焊

•Incomplete reflow of solder paste.

焊锡回流不完全

Cold solder/

冷焊

Countermeasure/ 对策

1. Peak temperature is too low or reflow time (dwell

time) is not enough: Re-setup the profile to fulfill the

paste spec or customer provided spec. requirement.

回流峰值温度太低或者回流时间不够: 重设温度曲线图.

Typical reflow profile:/ 典型的回流曲线

Preheat

stage

Soak stage

Reflow stage

Peak temp.

Cool

down

C/s