12.IC Crack(IC 裂_ )

拒收 良好情r

缺c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b炔亢有水 , 在焊高r饣造成
• Mishandling of IC packages during insertion 
• 零件置件r毫^大
• Excessive thermal processing during IC manufacturing.
• u程中整w囟冗^大 , 零件材料裂化

可行的A防方式 :

• Ensure that moisture is not present during fabrication
• 零件封br避免猱a生
• Ensure that the temperature of process stay within the IC tolerance
• _保u程囟仍诹慵格的S可

重工注意意事 :

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.