Breaking the Bridge Print E-mail
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Written by Paul Lotosky   
Saturday, 28 February 2009 19:00
Wave Soldering

Bridging is the unwanted formation of a conductive path of solder between conductors. When bridging occurs, the primary process setup areas to check are:

  • Conveyor speed too slow or other incorrect solder wave settings.
  • Time over preheat is too long, causing the flux to be burned off.
  • Dwell time too long, causing the flux to burn off before exiting the wave.
  • Topside board temp too low.
  • Not enough flux applied, or flux activity is too low.

Fig. 1

Other things to look for in the process include:

  • Preheat too high or low.
  • Solder wave height too low or high, or uneven.
  • Conveyor speed too slow or fast.
  • Board not seated properly.
  • Board pallet too hot.
  • Contaminated flux.
  • Contaminated solder.
  • Solder temp too low.
  • Flux-specific gravity too low.
  • Flux applied unevenly.
  • Flux not making contact.
  • Excess flux blow-off.

Fig. 2

Other causes to look for with the assembly include:

  • Board contamination.
  • Component lead length too long.
  • Component contamination.
  • Improper board handling.

Fig. 3

Other causes to look for with the bare board include:

  • Board oxidized.
  • Defective mask material.
  • Board contamination.

Other causes to look for with the design include:

  • Poor pallet design.
  • Internal ground plane.
  • Component orientation.
  • Lead-to-hole ratio too large.
  • Weight distribution.

Paul Lotosky is global director - customer technical support at Cookson Electronics (cooksonelectronics.com; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

 

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