11.Component Crack( 零件裂開 )

拒收 良好情況

缺點描述 :

Component split open usually on a corner

零件某個角落裂開 .

允收標準 :

For ICs : Minor chip-outs not exposing the internal circuitry.

For ICs : 以不看零件線路為原則

For chipped or damaged insulation on a component body ( e.g. resistor, transistor, capacitor ) : It is not acceptable if the damage extends into the functional portion of the component.

It is also not consider to be a defect if the damage is happening on the jumper or edge SMD part,but not changing the value of the part and do not cause safety problem.

一般的被動元件以不影響電氣 , 機構類元件以不造成安全危害為原則

可能因素 :

•  Internal moisture expands component
• 內部濕氣家熱時氣話體積膨脹造成
•  Radiant energy absorbed too quickly causing a mismatched in thermal coefficient of expansion 
• 瞬間熱能變化太大零件熱膨帳系數無法因應

可行的預防方法 :

• Keep components away from area that cause moisture
• 保存零件時避免環境濕氣滲入
• Keep the temperature value at a optimum level 
• 保持合理的溫度升降斜率

重工注意事項 :

• For multilead, fine-pitch component and IC :
  A thermode( heated tool of a shape which conforms to the pattern of the footprints of IC ) is pressed downwards against the horizontal ends of the gullwing legs to melt all the solder joint.The footprints is cleared by lightly fluxing and passing the tip of the chisel-shaped soldering tip across all of them.Again, the footprints is fluxed once more before the component is soldered back.

• For SMD :
  The solder joint is desoldered with the help of a chisel-shaped soldering tip and solder wick.The solder wick should be pressed into the corner long enough to let the heat travel into the gap underneath the component so that the solder is sucked out and the damaged component is replaced by another good one.

For through-hole component :
A desolder is used to remove the solder joint instead.Replacement of the damaged component is necessary before the joint is resoldered back.It is done by using a chisel-shaped soldering tip placed against it long enough such that the transfer of heat is sufficient enough before placing the solderwire close to the tip of the iron