This is the most fundamental skill needed to assemble any electronic project.
There is an accompanying video to show some of these topics listed below.
You should use a soldering iron with a power rating of between 15-25 watts for most project work. A higher wattage does not necessary mean that the iron runs hotter, it means it can cope with larger joints.
The simplest soldering irons don't have any form of temperature regulation but are an ideal general-purpose iron for most users.
A temperature-controlled iron has a built-in thermostatic control, to ensure that the temperature of the bit is maintained at a fixed temperature. Some irons have a bimetallic strip thermostat which gives an audible "click" in use.
If soldering a lot of static-sensitive components (e.g. CMOS chips or MOSFET transistors), then a soldering iron with static-dissipative materials would be advisable. This ensures that static does not build up on the iron itself. These may be described as "ESD safe" (electrostatic discharge proof). Otherwise take the usual anti-static precautions when handling the components.
It's useful to have different diameters or shapes of bits (soldering iron tips), which can be changed depending on the type of work in hand. These are often iron-coated to preserve their life. Do not try and clean these by abrasive means, as you will reduce their life expectancy.
The tip should be small enough so that the joint being soldered can be easily seen, but large enough to quickly transfer the heat required raising the joint temperature to the solder melting point.
Soldering irons should be used with an appropriate holder, so that it can be “parked” when not in use. Soldering stations usually have this feature, along with a holder for tip-cleaning sponges.
The sponge should be kept damp to clean the tip on.
Solder can be manufactured with or without a core of flux. For soldering electronic components and parts always use solder with a core of flux.
Normal electronics grade solder is now usually lead free and made from Tin, Silver and Copper.
Flux is a chemical cleaner, which removes oxidation from metal surfaces so that a good solder-to-metal bond can be made.
"Flux core" solder is usually in wire form. The centre of the wire is filled during manufacturing with the proper amount of flux required for soldering.
NOTE: NEVER USE CORROSIVE AND/OR CONDUCTIVE FLUXES TO SOLDER ELECTRONIC COMPONENTS.
Use the correct diameter of solder.
25 gauge or smaller. Used for soldering very small printed circuit (PCB) board pads and hand soldering surface mount components.
21 gauge. All around solder for printed circuit boards and general kit building/electronic repair.
19 gauge. Good for larger connections like tinning or connecting 14 gauge or larger wires to terminal strips, connecting multiple wires.
Do not use this for PCB soldering because excessive solder can be easily applied to pads increasing potential of solder bridges between points
Larger diameter solder should be reserved for soldering large items like very large stranded wires, soldering large items to aluminium chassis, etc.
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