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When icicles cool yields: resolving unwanted solder protrusions.

AN ICICLE OR flag (also known as a horn) is defined as an undesirable protrusion of solder from a solidified solder joint or coating.

Primary process setup areas to check:

* Conveyor speed too slow.

* Time over preheat too long, causing the flux to burn off.

* Dwell time too long, causing the flux to be destroyed before exiting the wave.

* Solder temperature too low.

* Not enough flux.

* Nitrogen use will help prevent icicles.

Other things to look for in the process:

* Solder temperature too low.

* Preheat too high.

* Excess flux blow-off.

* Solder wave height low.

* Preheat too low.

* Insufficient flux blow-off.

* Solder wave uneven.

* Contaminated flux.

* Board pallet too hot.

* Solder contaminated.

* Flux SP GR too low.

* Conveyor speed high.

* Flux not making contact.

* Flux applied unevenly.

* Conveyor vibration.

* Board not seated properly.

Other things to look for with the assembly:

* Board contamination.

* Component lead length too long.

* Component contamination.

Things to look for with the bare board:

* Oxidation.

* Contamination.

Things to look for with the board design:

* Poor pallet design.

* Internal ground plane.

* Large ground plane on solder side.



PAUL LOTOSKY is global director customer technical support at Cookson Electronics (
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Comment:When icicles cool yields: resolving unwanted solder protrusions.(WAVE SOLDERING TROUBLESHOOTING)
Author:Lotosky, Paul
Publication:Circuits Assembly
Date:Nov 1, 2009
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