introduction to soldering electronic circuits lab 2...
TRANSCRIPT
Introduction to Soldering
Electronic Circuits
Department of Electrical and
Computer Engineering
Kettering University
Mark G. Thompson, IME-100, 2002
Soldering Tools and Supplies
• Good quality pencil-type soldering iron
• Small gauge resign core solder
• Damp sponge
• Safety glasses
• Needle nose pliers/wire cutters
• Bench top vise for extra hands
• Braided de-soldering wick
Mark G. Thompson, IME-100, 2002
Soldering Safety
• Always wear safety glasses
• Solder on a fire resistant surface (never directly on a bench or desk top)
• Never leave a hot iron unattended
• Use caution when laying down or picking up a hot iron (tip temperatures are 700 – 800 degrees F)
• Use a soldering iron stand if available
• Replace the cord if it becomes worn or burnt
• Do not overload electrical outlets
Mark G. Thompson, IME-100, 2002
A clean tip is important
• A clean tip assures
good thermal contact
between iron and
component
• Clean the tip regularly
by wiping on a damp
sponge
Mark G. Thompson, IME-100, 2002
Holding the soldering iron
• Hold the soldering
iron in a relaxed
position, like holding a
pen
• Steady your arm by
resting it on the work
surface
Mark G. Thompson, IME-100, 2002
Correct component placement
• Place the components through the holes on the top side of board
• Check the alignment of polarized components
• Components should be nearly flush with the board surface
• Bend the leads outward on the bottom side to hold components in place while soldering
Mark G. Thompson, IME-100, 2002
Incorrect component placement
• Here the components
are not placed flush
with the board surface
• See the previous slide
for correct, flush
component placement
Mark G. Thompson, IME-100, 2002
Tin the tip
• Melt a small amount
of solder on the tip
before beginning;
called “tinning the tip”
• This procedure
reduces oxidation on
the tip and improves
heat transfer to the
component
Mark G. Thompson, IME-100, 2002
Soldering technique
• The component lead should be between the iron and the solder
• Heat the component lead and the PCB trace for a short time (max. 2-3 seconds)
• Touch the solder to the component lead (not the tip of the iron)
Mark G. Thompson, IME-100, 2002
Soldering technique (cont.)
• Feed a small amount of molten solder to the joint
• Some solder will be drawn up into hole, the rest will form a cone around the lead
• Pull the solder away first, then pull the iron away
Mark G. Thompson, IME-100, 2002
Good solder joint
• A good solder joint should be shiny and cone shaped
• Wiggle the component slightly to test for good mechanical connection
• Trim the excess lead length with wire cutters
Mark G. Thompson, IME-100, 2002
Bad solder joint
• A bad (cold) solder joint will be dull and glob-like
• The board may be discolored from over-heating
• These symptoms will lead to unreliable electrical and mechanical connection
Mark G. Thompson, IME-100, 2002
De-soldering
• If you make a mistake,
solder can be removed
from a connection
using braided de-
soldering wick
Mark G. Thompson, IME-100, 2002
De-soldering
• Place the braided de-soldering wick on the solder to be removed
• Heat the wick to melt and draw the solder into the wick
• Continue to use fresh wick until all solder is removed and component lead is free
Mark G. Thompson, IME-100, 2002
Completed board
• This is an example of
the top side of a
completed board
• Components are neatly
aligned with correct
polarity and placed
flush with the board
surface
Mark G. Thompson, IME-100, 2002
Completed board
• This is an example of the bottom side of a completed board
• Solder joints are shiny and cone shaped
• Board is not discolored from over-heating
• Excess leads are neatly trimmed off
• There are no unwanted solder bridges between connections
Mark G. Thompson, IME-100, 2002
Finishing Up
• Before finishing, invest some time in checking over your work. It could save you hours of trouble-shooting and re-work later.
• Look for solder bridges between connections, cold solder joints, missed connections, and reversed polarity on components.
• Touch up any solder connections that seem less than perfect.
• Once power is applied….it may be too late!
Mark G. Thompson, IME-100, 2002