User manual

3 Soldering Basics
3.1 What is Soldering?
In electrical engineering, soldering is one of the basic ways of establishing connections.
Soldering creates an electrically conductive connection that cannot be disconnected.
Using a melted metal binding agent (solder), soldering connects two metal work-pieces -
e.g. a PCB onto which an electrical component is soldered. The solder has a lower melting
point than the metals to be connected.
Soldering is performed at temperatures of around 340 °C. The metals to be connected do
not melt. The solder acts as a kind of adhesive. However, so-called mixed crystals form at
the transfer zone between metal and solder, forming a diffusion zone. The solder does not
just adhere to the metals to be connected, but enters into a crystalline connection with
them.
Using a looped solder connection, the mix crystal layer, that is, the area where solder and
each of the metals melt together, has a width of approx. 0.5 µm. If this transfer layer is too
large, the solder connection becomes brittle and porous. If the transfer layer is too thin,
the parts that were soldered together may disconnect again once you lift them up.
3.2 The Soldering Iron
Soldering irons are available in different designs and sizes. They must match the task to
be performed. For electronics applications, you need a soldering iron with a small solder-
ing tip and low connection power. Both ensures that you will be able to solder small com-
ponents well without heating them excessively.
Fine soldering iron
Fine soldering irons have a power consumption between 8 and 25 Watt (W). They are
best for soldering sensitive electronic components. A fine soldering iron is recommended
if you are dealing with small solder points.
12