SMT 缺陷.pdf - 第17页

11 Component damaged (Nicks, cracks, or stress fractures)/ 元件损坏 Nicks, cracks, or stress fractures. 缺口，裂纹，压痕

Solder hole/

锡洞

Countermeasure/对策

1. Insufficient preheat: Reflow profile optimize. 预热时间不足: 优化回流曲线设置.

2. Ramp up is too fast : Re-setup the reflow profile to make it optimize.

升温速率太快: 重设回流曲线图使之最优化.

3. Excess flux in solder paste: properly to increase preheat time and temperature.

锡膏助焊剂含量过多: 适当增加预热时间和温度值.

4. Damp PCB: Bake the PCB before loading it to SMT.

PCB受潮: SMT组装前烘烤PCB板.

5. Component feet oxidation: Bake it before SMT or require vacuum packing on

incoming material.元件脚氧化: 烘烤或者来料真空包装.

6. Attached flux residue on component foot: Sort out the defect part.

元件脚有助焊剂残渣: 挑选出缺陷来料.

Component damaged (Nicks, cracks, or

stress fractures)/ 元件损坏

Nicks, cracks, or stress fractures.

缺口，裂纹，压痕

Countermeasure/对策

1. Raw material damaged: purge the batch material./来料损坏: 清除这批来料.

2. Damaged during SMT process (Fixture or machine touch it) : Investigate and take

corrective actions for nonstandard operation.

在SMT流程中损坏(夹具和设备接触): 调查分析并且对不规范的操作作出矫正行动.

3. Fast cooling rate on reflow process : Control the SMA cooling rate to below 4degree

per second.

在回流过程中冷却速率过快: 控制SMA的冷却速度使斜率保持在每秒4度以下.

Typical reflow profile/ 回流曲线典例:

Preheat

stage

Soak stage

Reflow stage

Peak temp.

Cool

down

C/s

Component damaged (Nicks, cracks, or

stress fractures)/ 元件损坏