3-15
Figure 3-9.—On-the-board termination.
Q6. What term is used to identify the procedure of connecting one side of a circuit board with the
other?
Q7. Name two types of through-hole termination.
Q8. Turret, bifurcated, and hook terminals are used for what type of termination?
Q9. When a lead is soldered to a pad without passing through the board, it is known as what type of
termination?
Component Desoldering
Most of the damage in printed circuit board repair occurs during disassembly or component removal.
More specifically, much of this damage occurs during the desoldering process. To remove components
for repair or replacement, the technician must first determine the type of joint that is used to connect the
component to the board. The technician may then determine the most effective method for desoldering
these connections.
Three generally accepted methods of solder connection removal involve the use of SOLDER WICK,
a MANUALLY CONTROLLED VACUUM PLUNGER, or a motorized solder extractor using
CONTINUOUS VACUUM AND/OR PRESSURE. Of all the extraction methods currently in use,
continuous vacuum is the most versatile and reliable. Desoldering becomes a routine operation and the
quantity and quality of desoldering work increases with the use of this technique.
SOLDER WICKING.—IN this technique, finely stranded copper wire or braiding (wick) is
saturated with liquid flux. Most commercial wick is impregnated with flux; the liquid flux adds to the
effectiveness of the heat transfer and should be used whenever possible. The wick is then applied to a
solder joint between the solder and a heated soldering iron tip, as shown in figure 3-10. The combination
of heat, molten solder, and air spaced in the wick creates a capillary action and causes the solder to be
drawn into the wick.
