Learn To Solder
Your Activity
Learn how to solder
Materials
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Soldering Iron
Roll of Solder
Printed Circuit Board (PCB)
LEDs, Resistors , Capacitors
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Sponge
Wire
Wire Cutter
Flux
Create
1. Acquire a good soldering iron: The general desired
specifications are 40 watts and a temperature of 900 degrees. The
iron will get hot enough to melt the solder.
2. Acquire solder: The most recommended solder for Electronic
work is 60/40 rosin core solder. Most other forms will not conduct
well enough.
3. Prepare your soldering iron: For first use (and many uses
afterward), your soldering iron will need to be tinned. Allow your iron to heat up, and then melt a bit of
solder over the tip of the iron. Wipe the excess on a wet sponge immediately.
4. Get ready to make a solder connection: Place the soldering iron tip against both the wire lead and the
surface, so both reach approximately. Touch the solder to the side of the connection opposite the
soldering iron. The heat will be drawn through the work to reach the solder. Let a small amount of
solder flow into the surface until it is covered. Notice that this connection is soft and shiny and that the
solder blends smoothly with the terminal. Don’t use too much solder.
5. Tidy up: Clip off the excess lead at the top of the solder using wire cutters. Place the soldering iron in
the soldering stand. Test your circuit.
Science Topics
Electrical Engineering
What’s going on?
Soldering is the process of a making a sound electrical and mechanical joint between certain metals by joining them with a soft
solder. Soldering is an important skill to learn for those who want to make do-it-yourself electronics. Modern electronic
systems are formed of thousands of components and in turn, thousands of connections. The revolution in miniaturized
electronics would not have taken place without soldering.
Learning To Solder
Activity Lead Notes
Introduction
Good soldering is a skill that is learnt by practice. The most important point in soldering is that both parts of the joint to
be made must be at the same temperature. The solder will flow evenly and make a good electrical and mechanical joint
only if both parts of the joint are at an equal high temperature. Even though it appears that there is a metal to metal
contact in a joint to be made, very often there exists a film of oxide on the surface that insulates the two parts. For this
reason it is no good applying the soldering iron tip to one half of the joint only and expecting this to heat the other half
of the joint as well.
When the iron is hot, apply some solder to the flattened working end at the end of the bit, and wipe it on a piece of
damp cloth or sponge so that the solder forms a thin film on the bit. This is tinning the bit.
Melt a little more solder on to the tip of the soldering iron, and put the tip so it contacts both parts of the joint. It is the
molten solder on the tip of the iron that allows the heat to flow quickly from the iron into both parts of the joint. If the
iron has the right amount of solder on it and is positioned correctly, then the two parts to be joined will reach the
solder's melting temperature in a couple of seconds. Now apply the end of the solder to the point where both parts of
the joint and the soldering iron are all touching one another. The solder will melt immediately and flow around all the
parts that are at, or over, the melting part temperature. After a few seconds, remove the iron from the joint. Make sure
that no parts of the joint move after the soldering iron is removed until the solder is completely hard. This can take quite
a few seconds with large joints. If the joint is disturbed during this cooling period it may become seriously weakened.
The hard cold solder on a properly made joint should have a smooth shiny appearance and if the wire is pulled it should
not pull out of the joint. In a properly made joint the solder will bond the components very strongly indeed, since the
process of soldering is similarly to brazing, and to a lesser degree welding, in that the solder actually forms a molecular
bond with the surfaces of the joint.
It is important to use the right amount of solder, both on the iron and on the joint. Too little solder on the iron will result
in poor heat transfer to the joint, too much and you will suffer from the solder forming strings as the iron is removed,
causing splashes and bridges to other contacts. Too little solder applied to the joint will give the joint a half finished
appearance: a good bond where the soldering iron has been, and no solder at all on the other part of the joint.
Remember it is much more difficult to correct a poorly made joint than it is to make the joint properly in the first place.
Anyone can learn to solder, it just takes practice.
Background
Some of the world’s most important things depend on sophisticated electronics that require highly reliable soldering
Electronic circuits control the automatic operation of almost everything from the international space station to jet
airliners to the computer systems used in modern automobiles. In many cases, lives depend on the safe operation of
these electronic circuits. Modern electronic systems are formed of thousands of components and in turn, thousands of
connections. The revolution in miniaturized electronics would not have taken place without soldering.
Before the Activity
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Distribute one activity lesson per student.
Distribute one “Soldering is Easy” comic book per student.
http://mightyohm.com/files/soldercomic/FullSolderComic_EN.pdf
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Show a soldering video http://blog.makezine.com/2007/01/05/soldering-tutorial-make-v/
Go over the terminology & Safety Precautions
Procedure
If there aren’t enough soldering irons for each student, divide students into teams. We recommend maximum 3-4
students in a group.
Terminology:
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Printed Circuit Board: A board used for mounting electrical components. Components are connected using
metal traces “printed” on the board instead of wires.
Solder: A tin/copper alloy that melts at a very low temperature, used to join other metals together. It produces
excellent electrical connections.
Soldering: The process of joining two or more metals by applying solder to them.
Solder Melting Point: The temperature at which a tin/copper alloy (solder) melts. The common solder used in
electronics (63% tin / 37% lead) has a melting point of 370°F.
Capacitor: An electrical component than can store electrical pressure (voltage) for periods of time.
Resistor: Component used to control the flow of electricity in a circuit. It is made of carbon.
Polarity: The division of two opposing forces or properties.
Wire Gauge: Refers to the size of the wire. The bigger the number, the smaller the diameter of the wire. 18
gauge to 24 gauge is generally used for hook-up in electronics
Flux: A substance that is used to cleanse the surface of oxide before it is soldered. Always used in electronics
work. Most of the solder used in electronics has flux built right into it.
Oxidation: Most metals, when exposed to air, form oxide on their surface which prevents solder from adhering
to the metal.
Tinning the Tip: A process of coating the soldering iron tip with solder to minimize the formation of oxide on the
tip, which would reduce the amount of heat transfer.
Safety Precautions
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To protect your eyes, use safety goggles during all phases of construction.
Keep flammable material away from the soldering station.
DO NOT COOL IRON by dipping it into any liquid or water.
Always assume that the tip is hot to avoid burns.
Work in an area that is well ventilated.
Be careful that the hot soldering iron tip or the barrel of the iron does not come into contact with any electrical
cord.
Do not hold solder in your mouth. Wash your hands thoroughly after handling solder.
Locate soldering iron in an area where you do not have to go around it or reach over it.
Source
http://mightyohm.com/blog/2011/04/soldering-is-easy-comic-book/
http://blog.makezine.com/2007/01/05/soldering-tutorial-make-v/
http://www.wies-hs.eu.dodea.edu/Courses/PTS/Electronics/ComputerServiceSupport/css/Forms/Doc/SolderGD.pdf
Elenco – Solder Practice Kit Model SP-1A