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SURFACE MOUNT COMPONENT SOLDERING INSTRUCTIONS:
You'll notice that the circuit board contains only a few holes for component
leads to pass through. This is because the SMT components will be affixed to
the "solder" side of the PC board, the side that contains the PC traces. Be
aware that the component view for assembly is looking at the solder side of
the PC board.
Patience is the key when installing surface mount components. Typically, the
first step (after identifying the component) is to "tin" one of the PC traces that
will connect to the part.
Once this is accomplished, the part can be installed by holding it with tweez-
ers in contact with the "tinned" trace and re-heating the solder (see the associ-
ated diagrams).
This may go a little "against the grain" at first,
but it is by far the easiest method. Notice also
that when reheating the solder that the iron
tip does not come in contact with the "tab" on
the body of the chip component. Over heating
of this solder tab can cause a fracture of the
bond to the component, causing an intermit-
tent connection.
Another commonly used technique is to glue the surface mount components
to the printed circuit board before soldering. The procedure is to take a small
amount of glue (usually with a pin or toothpick) and "dab" the circuit board in
the place where the component will be affixed. Be careful not to apply too
DAP25 • 11
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