Indium Blog

Project 99: Combating Icicles in SMT Wave Soldering

  • Flux
  • Solder
  • Wave Solder

  • Icicles appear as stalactites hanging on the bottom of the circuit board during SMT wave soldering. Possible causes can include:

    • Solder temperature too low
    • Solder wave that is too high or uneven
    • Solder is contaminated
    • Preheat temperature incorrectly set (too high/low)
    • Flux is contaminated or its specific gravity is too low
    • Fluxer is set incorrectly
    • Conveyor speed is too high or angle is too small
    • Poor solderability of board or components
    • Component leads are too long
    • Excessive solder deposition
    • Insufficient flux activity

    Icicles are a common cosmetic defect and a real villain, visually unappealing, and indicative of a less-than-perfect process. Icicles also pose a danger to electrical integrity if they come into contact with other conductive surfaces.

    Shadow Warrior (WF-9958) uses a combination of stealth and strength to defeat a number of villains, including Icicles. He also defends against post-soldering electro-migration and corrosion, meeting the SIR and Electromigration requirements of IPC J-STD-004 (B). Shadow Warrior blends easily into the circuit board environment and allows electronic test probes to pass through him without altering his effectiveness.

    Shadow Warrior combines strength almost comparable to PCB-40 with the stealth and probe- testability of The Alchemist. And, as with The Alchemist, Shadow Warrior contains no rosin or halogens.

    If you would like to learn more about our Project 99 wave fluxes, or the procedures under which they were tested, contact us at