12.IC Crack(IC 裂開 )

拒收 良好情況

缺點描述 :

Visible or internal cracking of IC packaging and leads.

可能因素 :

• Packages’ internal moisture expansion resulting from exposure of device to temperatures above the melting point of the solder 
• 封裝內部含有水氣 , 在迴焊高溫時氣化造成
• Mishandling of IC packages during insertion 
• 零件置件時壓力過大
• Excessive thermal processing during IC manufacturing.
• 製程中整體溫度過大 , 零件材料裂化

可行的預防方式 :

• Ensure that moisture is not present during fabrication
• 零件封裝時避免濕氣產生
• Ensure that the temperature of process stay within the IC tolerance
• 確保製程溫度在零件規格的許可範圍

重工注意意事項 :

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 joints.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 IC is soldered back.