9.Wicking(燭心效應)
拒收 良好情況
缺點描述 :
Solder has been drawn up on the lead of a component.The copper pad has little or no solder.
PROBABLE CAUSES
- Solderability problem with the copper pad
- Deposition of too much solder paste
- Contamination of solder pad
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- Make sure that there is enough solder deposition on the solder pad
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POSSIBLE PREVENTIONS
- Improve solderability of pad
- Use component with clean leads as saturation prevents solder being drawn up
- Check the squeezee and stencil of the solder printing machine regularly to make ensure that correct amount of solder paste is printed on the PCB
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- Coat upper part of lead with solder resist so that solder will not be drawn up the lead.
- Use differentiating solder paste with varying temperature.
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REWORK
Wicking can be removed by touching it with a well-tinned tip of soldering iron.
