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 overheating • 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 desoldering wick
Mark G. Thompson, IME-100, 2002
De-soldering • Place the braided desoldering 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
