SMT 缺陷.pdf - 第11页
20 Non Non - - Wetting, Dewetting/ 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…
5、墓碑原理：在回流过程中零件两末端的表面张力不均衡．
9元件一头上翘，或元件立起
¾ PCB焊盘设计不合理
¾ 元件脚不规则
¾ 印刷焊膏移位
¾回流焊设备故障物料
¾其他原因如操作、传输等
STENCIL对SMT工艺的影响
2-2、常见SMT工艺缺陷分析:
元件末端氧化或者受污染：
根据情况做可焊性实验并且退还缺陷物料．
20
Non
Non
-
-
Wetting, Dewetting/
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
21
Cold solder/
Cold solder/
冷焊
冷焊
•Incomplete reflow of solder paste.
焊锡回流不完全