If you think
welding plays a minor role in the development of electronics, we will change
the way you think. We will also cover some of the items and equipment you can
buy to help you improve your skills in this area.
The art of
welding has improved over the years, to a point where it is 99.9999% perfect.
Each electronic product has hundreds of solder connections in its construction
and an on-board computer, for example, has thousands of connections. The chance
of a board failing in a life time-5 years is less than 1%. Consider the huge
challenge of this presents.
I have
watched it solder to improve since the early days of color television receivers
when printed circuit boards were filled with dry joints and failed sets every 6
months or so. When these sets came for repair, the only solution was to
completely re-solder the edge!
If the art
of welding had not improved, the computers would never have taken off. On a
similar ratio, a modern computer would not allow every 5 minutes!
It seems
incredible that a simple facet such as the weld would hold-up such a
development.
Over the
past 20 years, the quality of the solder has improved to a point where even the
smallest, cheapest, disposable product has a perfectly welded PC card.
Everything
is a matter of cleanliness, using the right fluid cleaning (flow), welding and
proper soldering at the right temperature. The composition of the solder is
extremely important. A change of less than 1% in the composition can make the
difference between a joint that binds properly and a "failure". All
printed circuit boards heat up and cool down during the operation and depending
on the elevation of the actual temperature, the solder connection may "internal
fracture." Solder is actually a very fragile material, perhaps because of
its low melting point, but also because of its composition, and is very
sensitive to fracking. That's why it's very easy to produce cracks in a
connection due to vibration or heating and cooling and movement.
There is
nothing worse than finding a PC card with solder cracks that develop over a
period of time due to faulty soldering. Sometimes dry joints can develop due to
heating and expanding components. This action puts tremendous pressure on the
solder connection and eventually it "breaks". In the worst case, you
can "maneuver" the component's head and remove it without the need
for de-welding!
The answer
is to re-solder the connection with a different type of solder or to add more
solder, so it is stronger.
There are
perhaps 100 reasons why a solder connection fails and if you think welding is a
simple science, I can assure you of a multi-million dollar company developed in
response to the industry's need. This company has actually saved the
electronics industry from ruin!
But the art
of welding has extended much further than simply making connections to a
standard PC card through hole. It has increased in '' MICRO CONNECTIONS ''
(welding of very small connections) and des-welding as well as soldering the
floods (wave soldering) where the board is totally immersed in welding for a
very short period of time and all connections are soldered at the same time.
THE
ART OF SOLDERING:
Before you
begin, there are three facts that will surprise you.
Regardless
of your level of welding skill, the quality of your workmanship will greatly
improve by:
1: using a
small temperature controlled soldering iron,
2:
Using a wet sponge to clean the tip of the iron, and tapping any excess solder before
starting a joint,
and
3:
Use of a welding fine.
You will be
absolutely amazed at how the quality of a joint will improve by following these
three pointers.
A soldering
iron, at normal low cost is way too hot for delicate electronic work. The
manufacturers of these irons generally allow the temperature to stabilize at a
high level so that the iron can be used for a number of applications, including
quite heavy copper wire connections.
The high
temperature of the boards makes the rosin (resin) in the center of the weld
"burn" too fast and it does not get enough time to clean the
connection. To compensate for this, you have to apply the extra solder and the
end result is the joint can become too hot and damage the component - especially
a diode or transistor or other semiconductor device.
The other
major problem with a constant heat iron is the resin forms a carbon layer
burned on the iron and this must be removed before starting each connection.
By simply
switching to a temperature-controlled iron, your soldering skills will produce
a much better "technical connection."
The seal
will be smaller and brighter (indicating the proper temperature has been
delivered during the welding process), less solder will be used and resin in
the center of the weld will have more time to clean the components.
You will
find the time needed to complete the brazing process will be shorter and this
puts less heat stress on the component.
Fine
soldering does not really go further but it may appear to go further because
less is needed for each connection.
But the surprising point is the fine solder produces a seal that has a better appearance.
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