Introduction to Soldering Electronic Circuits Lab 2...
Transcript of Introduction to Soldering Electronic Circuits Lab 2...
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