Most students who begin electronics are at some time introduced to
constructing a circuit using a soldering iron.
Many years ago I was placed in a similar situation, I remember being
told to tin the bit and apply the heat until the solder melted.
Useful advice I suppose but having many years later worked with a professional
wire man I realized how poor the soldering technique I used.was.
I will leave the health and safety aspects to your instructor, the object
of this short article is too make you far better than the average amateur
The basics of good soldering
the copper track that you are running the solder over must be clean
and free from dirt and grease of any sort.
Even a very small amount of grease from your finger will effect the
way that the solder will run over a joint.
The method that most electronic engineers use to clean the surface of
a board is to use an old toothbrush in conjunction with switch cleaner,
spray the cleaner on the surface and use the brush to clean the surface,
the alcohol content of the fluid soon evaporates to allow soldering.
Tip - Remember not to throw away your old toothbrush
2. Soldering iron
Most soldering irons are sold with a spade soldering iron tip at the
end, whist this is the best tip end for use on tag strips it is not the
best tip for general soldering of components.
I have found that the use of tapering bit is far more useful,
unfortunately the standard bit that seems to be supplied with cheaper soldering
irons is flat spade type bit shown below.
The more expensive temperature controlled irons are normally supplied
with a pointed bit, I have even successfully soldered with a tapering bit
with a small flat surface at the end (below).
Soldering iron tips that are tapering from the soldering experience
that I acquired are far easier to use than the spade type.
Unfortunately this is the type that seems to be supplied with almost
all of the cheaper soldering irons that I have seen for sale
Tip - If you are using a spade type tip for soldering components
into circuit board consider buying a replacement.
3a. Use of soldering iron
Before you start soldering make sure that your soldering iron is clean
and tinned, with regular use a thin layer of tin should form over the metal
of the bit, just melt some solder over the tip until a layer is over the
tip area that you will use for soldering.
Clean any excess off by using the sponge that will be on the tray
of the stand.
Get into the habit of cleaning the tip at regular intervals - some engineers
clean the tip every time they take it out of the stand.
To keep this sponge moist I would recommend that you find a empty washing
up bottle and fill this with water, this makes an ideal container for the
water that you will use when the sponge goes dry, you only need to make
the sponge moist so be careful how much water you add.
Tip - Remember not to throw away your next washing up bottle.
3b. Use of soldering iron - making good joints.
The number one error make by beginners to soldering
is applying too much heat over too long a period of time.
You should aim to apply the heat to make the
joint in the shortest time possible.
It seems to go against most learners instincts to apply the heat for
the minimum amount of time.
I have watched on an electrical installation course I attended, I was
except from the 2 weeks electronics part due to previous experience.
The job was to make a simple circuit on vero board, most students could
be seen seen with a large amount of fumes emitting from the iron bit.
The joints where taking several seconds to make, during this time fumes
filled the air, this was resulting in the joints starting to oxidize, the
longer the iron is held on the joint the more chance there is of the joint
becoming what is termed as a "dry joint"
A "dry joint" is a joint that is a poor electrical contact, all the
joints you make should be visually clean and shiny.
You are also in danger of damaging any semiconductor devices that the
soldering iron is in contact with excessive heat.
To give you an idea how long it takes for a professional wire man to
make a joint, I have seen a 60 pin IC soldered into a mainframe computer
board in around 40 seconds.
Keeping your board clean and using your soldering iron by the
methods described you will be able to apply the heat and get the solder
to flow in the shortest time possible.
You should aim to get the joint made in around 1 second.
A useful excercise would be to obtain some inexpensive chips and practice
increasing the speed at which you could solder them into a circuit board
( e.g. vero board) .
Buy a solder sucker and learn to use it to remove the chips and then
The chap who I sat next to on the electrical installation eventually
grasped the idea of how to make good soldered joints.
Every time I saw the fumes filling the air I keep telling him "He was
doing it wrong".
Finally good luck with your electronics studies - I hope following the
advice given you will be able to grasp the skills required in mastering
the use of the soldering iron