Solid connections are essential to
the operation of an LED circuit. In this tutorial I will show
you how to make perfect connections every time.
I don't claim to be an expert, but I have taken several classes
throughout my 30+ years in the field of electronics and I've had a
lot of practice.
It's kind of like an art but anyone can
learn it and do it well with some practice, as long as you know the
It is a very important part of
electronics. It is used as a means to electrically connect two types
of metal together. In other words, you melt some metal, to connect
some metal, to some other metal. Easy, right?
conductive. It allows two parts of a circuit to become one. If I
want to connect the Cathode of an LED to one end of a resistor, I
could twist the leads together but this is not a very efficient way
to connect them in a circuit, especially if I have a lot of LEDs and
resistors to connect.
I could twist them and then solder them
together, (Which is known as point to point) but that's not the
prettiest way to do it either.
most widely used method is to use a PCB (Printed Circuit Board) with
Traces or Tracks, and solder the components (LEDs, resistors,
capacitors, etc.) together.
Now a PCB is not the only way to
connect things. You might want to connect two wires together, or
build a whole circuit using point to point wiring.
show you several ways to connect different types of electrical
things together (sounds technical, huh?) including
Solder typically melts at around 400
degrees Fahrenheit, although there are some types that melt at lower
There are several different types being used
today. The most common for electronics is called rosin core. It
contains a 60/40 mix of tin and lead and is manufactured with tiny
holes or tubes that are filled with rosin flux.
Flux helps remove
impurities (specifically oxidized metals) from the points of contact
to improve the electrical connection.
Let's Be Green
Recently, due to concerns over
atmospheric pollution and hazardous waste disposal, the electronics
industry has been gradually shifting from rosin flux to
water-soluble flux, which can be removed with de-ionized water and
detergent, instead of hydrocarbon solvents. This is especially good
because harmful chemicals are not required to clean a circuit board.
The Tools Of The Trade
There are many "tools" that you can
use. Here is a list of some of the more important ones:
A good soldering station or stand alone iron. Something between 15
and 40 watts is best for circuit boards.
* A small
wire brush for cleaning the tip.
* Solder. It used to be
that a 60/40 Tin/Lead mix type with rosin flux mixed in was the way
to go. But due to concerns over atmospheric pollution and hazardous
waste disposal, the electronics industry has been gradually shifting
from rosin flux to water-soluble flux, which can be removed with
de-ionized water and detergent, instead of hydrocarbon solvents. A
smart choice if you are concerned about the environment. I
personally prefer a .025" diameter. In my opinion, it's just the
right size for most projects.
SolderWick or a sucker for
* A pair of tweezers
and/or a small pair of needle-nose pliers. These are used to bend
leads. A must for installing components.
* A good pair
of cutters, (Side Cutters, Dykes, Diagonals) for cutting component
An acid brush for cleaning flux off the circuit board.
Flux remover, whether it be for the old style flux or the water
* A helping hands tool.
This handy tool will help you by holding the PCB while you are
making your connections.
* A magnifying swing arm light. While this may not be
necessary for all, for an old guy like me, it's a must.
A small fan is a good idea. Melting solder creates some nasty smoke
that you really don't want to breathe too much of.
Eye protection is very important.
I've seen first hand what can
happen when 400 degree solder flips up into the eye. A fellow
student in college ended up in the hospital. It wasn't pretty so use
eye protection, please.
Soldering can be a simple task as
long as you follow a few simple rules.
Rule #1. Always
keep the iron's tip properly tinned.
Rule #2. Always
make sure the joint is clean.
Rule #3. Always make
sure the components are the same temperature as the iron.
Rule #4. Never leave the iron's tip on the objects for too long,
bad stuff can occur.
Rule #5. Practice makes perfect.
Follow these simple rules and you should have no problems... ;o)
Now, To Explain The Rules
tinned iron will last a long time. I like to keep a wire brush handy
to lightly brush the tip after the iron has warmed up. Then I apply
solder to the tip until it coats it all the way around and up for
about ½ an inch.
Once coated, clean the excess off the tip
with a wet sponge. It should be nice and shiny. Now
re-coat the tip
slightly again and just leave it on there. This will help to protect
I always try to turn off my iron if I don't plan to use it
for an hour or longer. The heat seems to eat tips.
tip's tinned so the iron's ready. For PCB's, (Printed Circuit
Boards), make sure the surfaces are clean. Remove any old solder if
and clean off any flux, old glue, paint or anything else that might
prevent a good connection. The copper pads should be shiny and
insert the component into the board. If you need any tips on
installing components, go to my
page. Using the Helping Hands Tool
here to hold the PCB makes the job easier. Extend the leads from the
component so that they are stress relieved. Bends should be at least
two lead diameters from the component. Never bend right next to the
body of the component. When you bend the leads, keep in mind that
you want to be able to identify what the part or part number is once
the part is in place.
Here We Go
installed, you can bend the leads a little to hold the component in
place since the PCB is upside down.
With the component firmly in
place, clean the tip of the iron with the wet sponge, add a little
solder to it and touch it to both the PCB pad and the component lead
at the same time.
Start applying solder to either the
component lead or the PCB pad. The idea is to make the two parts you
are joining together the same temperature as the iron tip. When it
melts on the parts it will flow quickly.
If you try to use the
iron's tip to melt the solder, you might end up with what is called
a "cold connection/joint".
These connections sometimes fail in
time due to corrosion or just lack of contact.
Important, don't leave the tip on the
joint for too long. Electronic components are heat sensitive and can
be easily damaged. Sometimes, if you're having trouble, it is a good
idea to use a heat sink (Alligator Clip) to take some of the heat
away from the component.
A good connection should take only about
2 seconds to complete. If it takes over 5 seconds, something is
wrong. Go back and check to see if everything is properly prepared
before trying again.
Once the iron is removed, the joint must not
be moved until it has hardened and cooled, usually a couple of
Poor connections can have a rounded, lumpy, dull,
irregular, or granular appearance indicating improper solder
Here is an
example of a good joint. Notice the shape, and the color is a nice
One More Thing
All of the information on this and
any other page on this website is to be done at your own risk.
Soldering irons are very hot and can cause severe burns. Melted
solder can easily fly and get into places you don't want it, so be
careful. ALWAYS USE EYE PROTECTION. It's just a good idea. If you
get hurt or damage anything, IT'S NOT MY FAULT. Please use good
judgment when performing these tasks. BE SAFE AND SMART.