Figure 3-10.Solder wicking.
This method should be used to remove surface joints only, such as those found on single-sided and
double-sided boards without plated-through holes or eyelets. It can also remove excessive solder from flat
surfaces and terminals. The reason is that the capillary action of the wicking is not strong enough to
overcome the surface tension of the molten solder or the capillary action of the hole.
MANUALLY CONTROLLED VACUUM PLUNGER.The second method of removing solder
involves a manually controlled and operated, one-shot vacuum source. This vacuum source uses a plunger
mechanism with a heat resistant orifice. The vacuum is applied through this orifice. Figure 3-11 shows the
latest approved, manual-type desoldering tool. This technique involves melting the solder joint and
inserting the solder-extractor tip into the molten solder over the soldering iron tip. The plunger is then
released, creating a short pulse of vacuum to remove the molten solder. Although this method offers a
positive vacuum rather than the capillary force of the wicking method, it still has limited application. This
method will not remove 100 percent of the solder and may cause circuit pad lifting because of the
extremely high vacuum generated and the jarring caused by the plunger action.
Figure 3-11.Manual desoldering tool.