Despite all my efforts I cannot eliminate icycling on my t/h leads. They come and go.... daily, lots of rework. I have eliminated the following from the scenrio: Inadequate flux to promote quick drainage, Pot temperature too low, Soldering surface unusually heat absorbent, Leads picking up dross in the wave, Wrong Plated Through Hole to wire ratio, Conveyor angle, Preheat temps. insufficient,
What about conveyor speed? I tried to manage that the speed of the board and the speed of the wave were nearly the same at that point where the leads are leaving the wave. But actually I haven�t seen icycling except at one time and that was solved rather quick, as I remember right after all this years, with getting the flux mixture right again but I wouldn�t put my hands in fire for that, could also be that it was that preheat trouble we once had ( one of the IR plates decided to do something completely different with no further notice to anybody ).
As Wolfgang says: Conveyor speed may be too high. Excuse me for not stripping-out my repetition from your list, but other machine adjustments to consider are: * Using more efficient [higher specific gravity] flux. [Got it!!!] * Adjusting wave shape and / or conveyor angle. [Got it!!!] * Increasing solder pot temperature. [Got it!!!] * Increasing pre-heat temperature [to 160�F???]. * Using only single wave solder, not double wave solder. * Checking your solder pot for metallic impurities.
Icicling may have sources other than machine adjustments, such as: * Improving solder mask. * Using more efficient flux. [Got it!!!] * Redesigning board to remove large open land areas. [Got it!!!] * Cleaning the boards. * Correcting the lead solderability.