Tip maintenance of your soldering iron is a necessary
action. Without proper tip care your
soldering days are greatly reduced and tip replacement comes sooner than
expected. With high heat needed for soldering, especially for lead-free
soldering, tip burnout is more likely to occur.
Temperatures of 700 – 750 degrees Fahrenheit for lead-free and 650 – 700
degrees Fahrenheit for tin/lead are not uncommon. Some soldering stations are capable of
reaching 900 degrees Fahrenheit.
As you can see lead-free solder requires a much higher heat
to melt. Sometimes this leads to “cold
tips” where the ends turn black and the solder fails to adhere to the tip
surface. You may think the tips are not heating properly when the solder just
balls up and falls off the ends. But,
don’t be fooled, this stuff is still hot and can burn you. Shown below is an example of how some manufacturers have overcome the overheating problem. This technology is built into the soldering tips that I prefer to use for my own jobs.
Smartheat Soldering Tips
With tips generally made with a soft copper core the outside
is coated with some form of metal alloy such as iron. Iron can withstand an immense amount of heat
over a long period of time. However, if
the iron or other surface coating is damaged, such as scratching or bending,
the tip will incur heat loss and the “cold tip” syndrome will commence. Iron can also corrode causing
dewetting.
In order to prevent premature tip failure a few things can
be done to negate this. Turn the heat
down! When not using the soldering station for five to ten minutes turn it
off. This will help in maintaining a
longer tip life. Most modern soldering
stations can heat up and cool down within just a few seconds. So, why not utilize this feature and save
your tips from an early grave? Heat wears out tips.
Next, make sure the tip is clean and tinned prior to placing
it back in the holder. Tips will wear
out much quicker when not properly cleaned and tinned. Lastly, use the proper cleaning tools for tip
maintenance. A battery terminal scraper
is not the correct tool for cleaning soldering tips.
Another useful thing to remember is to keep your solder
types separate. Lead-free solder should
never be used with a tip that is used for tin/lead RMA or non-rosin core
solder. When you mix solder types the
layer of solder left on the tip from tinning will have a lasting affect every
time you use the tip.
Example of the proper way to maintain soldering tips
Now, it’s not to say that you can’t use the same tip for
each type of solder. However, the
extreme cleaning action needed to completely remove the
tin/lead or lead free solder from the tip is harder to accomplish than just
switching tips. “Why not just keep tips
separate for lead-free and tin/lead?
This would negate any problems down the line if you perform both types
of soldering on a continuous basis.
Let’s take a look at maintaining a tip utilizing tin/lead
solder. Since tin/lead soldering is the
most widely used method in electronics manufacturing I will cover that
first.
Before you start soldering, the tip of your iron should be
cleaned of any residual solder, flux, or debris. Start by heating up the tip to
its normal operating temperature that you have set. Next, clean the tip on a sponge and then with
some soft brass wool or “brass brillo” as we call it in the industry. Ensure you use a cellulose sponge and not a
synthetic sponge. The synthetic types
will melt when the tip comes in contact.
In addition, remember to use only deionized water. Regular tap water has minerals that will
shorten and damage the life of your tip.
Example of Brass Wool or "Brillo"
Make sure all solder has been removed. Next, melt just a dab on the tip to prevent
oxidation. A dirty tip with no tinning
will not conduct heat properly from the tip to the part to be soldered. You can also use a burnishing tool if you
don’t have access to a rotary cleaner or a can of tip tinner. I don’t recommend using a burnishing or
polishing tool unless you don’t have any other method of cleaning your
tips. Tip tinner works well for tips in
removing burnt on flux and debris. Just
roll the heated tip around inside the tinning can until the black color turns
to silver and you know then that it is clean.
Once cleaned, remove the excess tip tinner with the sponge and brass
brillo. Then re-apply solder to tin the
tip properly. Tip tinner is not meant to
be left on the tip. It is only for
cleaning the tips and nothing else.
Example of Tip Tinner
If you have cleaned the tip properly, and the solder has
adhered to the tip while pre-tinning, then you have successfully cleaned the
tip. If the tip is not cleaned properly
and the solder just balls up as you try to tin the tip, then more than likely
it is still dirty or damaged.
Never and I mean never, bend or dent the tips to another
shape. Never pull a tip out or install
with a pair of pliers. Soldering tips
are meant to apply solder and not to be bent to a different shape. If you need a 90 degree tip and only have a
straight tip then spend the money and get the right tip. When you bend a tip or damage it by yanking
on it with pliers the tip becomes ineffective in completing the soldering job
efficiently. Heat transfer is lost due
to the damage incurred.
In some instances the sponge and brass wool become
ineffective in cleaning your tips. There
are rotary motor driven tip cleaners that can remove more oxidation than normal
cleaning can provide. These units are a
little more expensive than hand cleaning methods. However, if you are a serious solder
technician they are worth the cost. I
personally use one in my own lab on a monthly basis and they save time and
money replacing expensive tips.
Example of a soldering tip polishing tool
When using lead-free solder, cleaning and maintaining the
tips are pretty much the same as with tin/lead tips. However, temperature ratings are much higher
for lead-free tip usage and therefore the tips tend to wear out much sooner.
So, when you decide
to perform maintenance on your own tips remember to treat them gently. A well maintained set of tips should last for
a very long time. I have tips that are
over five years old and still perform as if they were bought just yesterday.