SMT焊接不良及图片说明3--零件面a多
日期:2009-11-04 10:09 点击:423
3.Excessive Solder-component side( 零件面a多 )
拒收 良好情r
缺c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
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- 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
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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
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- 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
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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.
