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SMT焊接不良及图片说明3--零件面錫多

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核心提示:3.Excessive Solder-component side( 零件面錫多 )拒收           &n

3.Excessive Solder-component side( 零件面錫多 )

拒收                                    良好情況

缺點描述 :

Wetting angle to base metal is steep and joint surface is not concave.

PROBABLE CAUSES

  • Solder temperature too high or low
  • Solder wave height too high
  • Solder wave uneven
  • Conveyor speed too low
  • Board not seated right
  • Board rerun
  • Incorrect weight placement and excessive weights used  
  • Defective fixture and pallet design
  • Excessive mask ( temperature )
  • Board warped
  • Large plane on component side
  • Hole to lead ratio large
  • Weight distribution
  • Large unfilled holes  

POSSIBLE PREVENTIONS

  • Maintain the accurate solder pot temperature
  • Maintain the correct solder wave height 
  • Ensure that the solder wave is even
  • Maintain the correct conveyor speed
  • Ensure that the board is place evenly before soldering
  • Correct weights should be used for pinning the board down  
  • Reduce any excessive weights used for pinning the board down
  • Preheat temperature should not be too high that causes the board to warped
  • Make no or less large plane on component side
  • Ensure that the hole to lead ratio is correct
  • Have no or little large unfilled holes 

REWORK

Excess solder is removed from the joint by touching it with the well-tinned tip of a soldering iron in order to remove the excess solder.

 
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