onto the leads you want to solder, you first rub
the tip across the wet sponge to clean it. Then,
you melt a little solder onto the tip to make it
easier to transfer heat to the items being
soldered.
You will also need a pair of cutters to trim
off the excess leads after you have soldered
them. This is necessary whether you are
soldering components to a printed circuit board
or twisting them together to make a
connection. When you clip the leads, wear
goggles to protect your eyes as the leads
sometimes fly away very quickly when cut. You
may want to point the lead being clipped down
directly into a wastebasket while clipping it,
both to protect your eyes and to catch the
clipped lead.
You should wear long pants while
soldering. Since you are almost always sitting
while soldering, it is not uncommon for molten
solder to accidentally drip off the tip of the
soldering iron when you pull it away from the
circuit. Sometimes the molten solder drips onto
the table where you are working, but it could
drip onto your legs. It is very hot and will easily
burn you if it falls on your bare skin.
FIGURE 2. Here is
everything you
need to solder an
electronic project.
Soldering To A PCB
If you are soldering components to a printed circuit
board (PCB), it is important that the copper traces on it
are clean. Copper will slowly oxidize when exposed to
air (actually, the pollutants that are in air). This thin layer
of oxidation will make it harder for the solder to adhere
to the copper. It is a good idea to gently rub the traces
with steel wool or fine sandpaper before soldering
anything to them. This removes the layer of oxidation
and makes tiny scratches in the copper, which also
increases its surface area and gives the solder more
places to attach. After you have cleaned the traces, be
sure not to touch them with your fingers. Hold the PCB
by its edges as the oil on your fingers will deposit on the
copper and begin oxidizing it. If you wait long enough,
you will eventually see the pattern of your fingerprint
etched in the copper!
It is usually necessary to solder wires to a PCB to
carry power to the board and signals to the off-board
components such as switches and speakers. If the wire is
stranded, you may want to tin the wire before soldering it
to the board. Tinning places a small coating of solder over
the wire and makes it easier to work with and solder to
the circuit board. It also makes the wire stronger and able
to put up with some bending without individual strands
breaking off.
How To Tin A Wire
First, the bare stranded wire is twisted to make a
tight rigid tube with all the wires going in the same
direction. Then, solder is applied to the tip of the
soldering iron and the tip applied to the wire. Melt a small
amount of solder onto the wire until it is evenly coated.
With the wire tinned in this way, it can easily be pushed
through a hole in the circuit board, or bent into a shape
that it needs to be in, or wrapped around a screw before
it is tightened down.
Keeping the PCB or other items you are soldering
steady is important. It is very frustrating to try and
Putting
work in a
vise is like
having an
extra pair
of hands.
Solder braid
for removing
solder.
Solder sucker.
February 2009 65