Episode: 1037
Title: HPR1037: Soldering Part 1
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr1037/hpr1037.mp3
Transcribed: 2025-10-17 17:46:44

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Hello and welcome Hacker Public Radio audience, my name is Mr. Rex. Welcome to my second
HPR podcast. It's been a while and I must apologise for the long interval that has passed
as well as the show. I suspect this spent too much time preparing my show mostly due
to lack of confidence on my part. I would like to start by thanking the people at HPR
for making all this possible. I would never have pulled my first podcast together without
them making this series available. It's truly a wonderful and invaluable resource on
these here intertubes. If you have something interesting or some busting passion, why not
share it with the rest of us? It truly isn't that hard. I'd even if you only manage one
show that's fine and great. But who knows, you might even enjoy the challenge and produce
more shows. I can do it, anyone can.
As they show, I'm going to talk about soldering. This will be a two-part podcast. I'm going
to take a very practical approach as I have no expert in the exact signs of our theory
of soldering. But I do know how to solder. I know how to produce a consistently good
soldered joint. I used to be pretty handy with a soldering arm. It was something I was
quite proud of, but it's now something I hardly ever do. And while I may not be as good
as I used to be with less steady hands and pure eyesight, I think I'm still reasonably
proficient. I guess it's a bit like riding a bike, you never quite forget how to do it.
I'll be covering the history of soldering, the various tips of soldering I have, you
can get, with a pros and cons. My recommendations, handy tools, latest techniques and the future
of hand soldering. If you plan to dabble and have a go at soldering, then I hope you find
this podcast interesting and informative. Sit back and enjoy.
Nobody knows when it was first discovered how to glue metals together. Goldsmiths of ancient
Egypt knew how to join gold more than 5,000 years ago. Many of the pieces of jewelry,
tools and weapons we know from the Bronze Age were given their utility and beat it by soldering.
A soldering spread around the globe, the art of soldering was improved from culture to culture
and from generation to generation. The ancient Roman soldered 400 km long water pipes
made of lead, with seams which grew to stand huge pressures, and kindred up stoves and
tubs made of bronze. Great improvements were made in the last century, not only were craftsman's
skills improved, but also our understanding was refined in the scientific interactions which
take place during soldering. Soldering became indispensable in the manufacturing
electronics industry. Mass market soldering hours became available around the 1950s.
Hand soldering in industry peaked many years ago and like many other trees is now a dying skill.
Most of the components fitted onto modern circuit boards are too small to be hand soldered,
but there is still room for it in the hubby's toolbox, particularly if you need to perform a
simple repair, build a unique simple circuit or perhaps a custom cable. Whatever the reason,
it's certainly very satisfying to build or repair something with your own two hands.
Recently we started to having problems with our home cordless phone.
The buttons on it started becoming intermittent and unresponsive,
and the problem was getting progressively worse, to the point where it was difficult to dial a number.
I carefully removed the back of the phone and found that in order to get access to the button
membrane, I would have to unsolder connections to two resistors and two wire connections to the
handset microphone. Without the skill of soldering, this full phone would have been unnecessarily thrown
away. I spayed some switch cleaner onto the switch contacts, cleaned up the button membrane,
resoldered the connections and reassembled the phone. This transformed the function of the phone,
the buttons on now are light and responsive. Repeating this item was very satisfying,
and with 7 billion of us on the planet, one less thing thrown away can't be bad.
On top of all of this, I have grown somewhat attached to the phone as it is now over 10 years old.
Why don't I give soldering a go? It truly isn't that hard, and like me, you might end up getting great
satisfaction from it.
My soldering irons
My first introduction to soldering was by my father at the kitchen table. I was young boy at the time.
My father had previously been a blacksmith. As a blacksmith, he would make and fit horse's shoes.
Create iron gates and fences. He kept some of the old rusty tools he had used in a black
wooden box. Many of the tools he made himself. One of these tools was an old rusty electric soldering
iron. The iron had a wooden handle and had an iron wire wrapped around outside of a hollow cylinder
that contained the tip. The iron wire heated up when electricity from the mains was passed through it.
My father didn't have any interesting electronics, so I'm not sure why he had the iron.
He probably introduced me to it because I bugged him to let me have a go at soldering,
because at that time I was fascinated by electronics. Together we ended up making a rather
unimpressive, simple flower shape out of stiff pieces of wire soldered together.
A modern soldering iron also uses an iron wire, but this is packed with a metal tube filled with
magnesium oxide. The magnesium oxide is used because it's an electric ventilator and it stops
it out of casing becoming live. It is used because it remains stable at high temperatures.
The first soldering iron I ever owned was a rather expensive battery-powered soldering iron.
I've probably given this because my parents thought it was less dangerous than soldering iron
per from the mains. While this is true, it didn't stop slipping one time and burning the edge of my nose.
There are quite a few places you wouldn't want to stick a soldering iron, and I can tell you this
is one of them. I guess you only learned from your mistakes, and I certainly never made that one
again. This probably happened because at the time I had no idea how to sold it properly,
but I had plenty idea how to sold it improperly. This iron was slow to heat up,
was often not powerful enough. The battery went flat very quickly. It had a bulb at the front,
which we'd like to help you see what you were doing, which usedfully helped flatten the
penny battery even quicker. I would regularly pass the unscrew the bulb so we could get a few
extra seconds of use from the thing. My second soldering iron was a weller soldering gun. It used
low voltage and high current to heat the copper dip. It came with a variety of attachments for
craftwork like scorching cork, melting and cutting plastic. It also came with a strip of
PTFE tape, as polytetra floral ethylene, which allowed you to reseal a polythene bags.
You simply placed the PTFE strip on top of the polythene bag you wanted to seal,
and then run an iron over the strip. The PTFE strip has a high melting point and was
unaffected by the heat generated by the iron, and the heat transferred to the bag,
fusing it shut. Or at least that was what was supposed to happen.
Also as the PTFE is one of the most slippery substances known to man, the polythene bag did not
stick to it as it was fusing. In practice, the results obtained were a little varied,
and I just picked a cat to see the point of this iron. It was heavy,
they've got to handle, had a big clumsy tip. It overheated when used for long periods.
Yet for all this it became very popular. People had them everywhere.
The only advantage I can see it had was it may have heated up quicker than a standard soldering
iron. So it was handy for quick jobs.
My third iron was a gas-powered soldering iron made by Porter Sol. It was in the shape of a fat
pain. It isn't as daft as you would think. It certainly worked far better than my battery
powered soldering iron. It held the gas for a long period of time,
and actually the gas would leak out, but this wasn't a problem since it could be charged within
seconds. And at plenty of power, the output power was variable by the way of a knob in the back.
I got very attached to this iron, and I still have it today. And while I haven't used it in
years, I'm sure it still works. His biggest weakness was the quality of the tip.
I'll discuss tip quality later on in the podcast.
My fourth iron was finally a proper soldering iron. It was Nantex 25 watt iron.
This was a cheap iron and was very popular at the time, and came highly recommended.
However, it was still far from perfect. But what fine once I modified it.
The double of this iron was that it tended to overheat. Now when I see overheat,
I don't mean glow red or catch fire or anything. I'm sure I could have left it on all day,
and it would be perfectly safe. The problem was that it ran so hot that it tended to destroy
the tip. This meant that it was difficult to keep the tip clean and shiny, which in turn made
a difficulty looking good soldering joint. My fifth and final soldering iron is a weller
electronic soldering station model EC2000. This iron is rather scabby but I'm very attached to it.
I'm also very proud to own it. To replace it would be very expensive. Luckily,
it is so well built that I suspect it will last longer than I will.
I bought it second hand from a man I know many years ago for a not unreasonable summer 40 pounds.
The tip temperature can be set very precisely. I generally run mine at 330 degrees.
Yeah, as two switches are variable control and an LED display.
First you switch on the main switch. Then flip the second switch to the set position.
Then adjust the rotary control to your desired temperature while looking at the LED readout.
Finally, the switch is set to read and the display now reads the actual measure temperature at
the tip of the iron. Add a short space of time the tip stabilises within a degree or so
of your set temperature. This sort of temperature precision is needed when the circuit board being
soldered is delicate or the components themselves are sensitive to heat. If the temperature is not
acutely controlled, when the circuit board lands can lift or the heat sensitive components can be
destroyed. A land and soldering term is the pad where you place solder onto that fixes the
components in place. For most people, this sort of soldering iron is complete overkill.
I was very lucky to get hold of this iron. I would now certainly be far too mean to pay
the money to replace it. I just hope it lasts forever.
Some of the gadgets and tools I own have become very attached to this iron as one of these things.
Just like my trusty science 3CE which I still use daily and in all the 20 or years I've owned it
has never lost a single piece of information. How many other computers have this kind of track record?
An uptime of about 20 years. However, I digress. The show must go on.
Older and cheaper soldering irons have a bare copper tip. These should be avoided.
Over time the copper tip dissolves into the solder. This causes pitting and erosion of the tip.
Causing it to deform and making it difficult to use. This kind of tip is also very difficult to keep
clean. A much better solution and the one which most modern soldering irons use is an iron plated
copper tip. The iron plating does not dissolve into the solder so it keeps its shape and is usually
easy to keep clean. I say usually because there are a few reasons for this not always being the case.
A cheap soldering iron may contain very thin iron plating which may wear off over time.
Another more common problem with cheap soldering iron is that they may operate at too high
temperature when sitting unused which in turn leads to the slow destruction of the tip, especially
if it has a cheap tip. This is exactly the problem I had with my antics 25 watt iron.
The iron came highly recommended within the electric magazines of the time and when it arrived
I was pleasantly surprised that it felt very good quality with a good quality tip. Yet that
itself was fairly cheap. I think this iron may still be available today. I would say that it is one
of the better non-temperature controls and if you are looking for a budget iron there is probably
a reasonable choice. I forget a chance I'll put a link to in the show notes.
The problem with this iron was caused by the fact that it wasn't temperature controlled and hence
often run too hot. This made giving the tip clean and shiny difficult. I guess the manufacturers
make it this way so that it can cope with heavier soldered joints. Certainly for normal
products on exoldering I found it run far too hot. Perhaps I would have been better with a
15 watt iron but again if not temperature controlled it too would probably run too hot.
I came up with a solution which involved opening up the mains plug and distancing the live wire.
I soldered a heavy duty bridge rectifying diode onto the end of the live wire and attached
other end to the live term of the plug. This was a job where my trusted gasberg
Portisol soldering iron came to the rescue as I could hardly use my mains powered soldering iron
whilst poking around in its mains plug. The diode was connected in series with the live terminal
of the plug. This had the effect of chopping off one half of the mains voltage cycle.
The iron now took much longer to heat up and could have done with being perhaps a little hotter
but at least the tip stayed clean and the iron became usable. After this mod the iron served me
well until it was replaced by my trusty well attempted controlled soldering iron. I kind of
vouch for the safety of this hack and if you choose to do likewise then you do so at your own risk.
If you can afford it I highly recommend buying attempted controlled iron. This will stop you
having the overheating problems like I had with my antics 25 watt iron.
Various methods are used to control the temperature of soldering iron tips. The simplest uses a
variable power control much like a light dimmer that just varies the amount of power being fed to
the iron. This type of iron is not thermostatically controlled. The temperature of the tip is roughly
set by the amount of heat lost to the environment. This means that while soldering the temperature of
the tip can vary greatly from when it's sitting idle doing nothing. Another type of iron uses a
thermostat often inside the iron's tip which switches power on and off to the element.
A more advanced version of this uses a microprocessor to monitor the temperature of the tip via a thermal
couple and adjust the power to the heating elements accordingly. Yet another approach is to use
a magnetized soldering tip which loses their magnetic properties at a certain temperature.
Other complex irons circulate a high frequency AC current through the tip using magnetic physics
to direct heat only where the surface of the tip drops below the desired temperature.
At work I mostly used magnetetically controlled weller soldering stations. This consisted of a soldering
iron with heat resistant silicon cable which plugged into a transformer unit with a coil spring
stand which held the iron and a soldering sponge and a metal tray for holding spare tips.
These were fairly expensive irons with a very good quality tip that seemed to last indefinitely.
It wasn't uncommon for these irons to be on 24 hours a day, year after year, and yet the tip still
remained good. A number was stamped on the rear of each tip which indicated the temperature the
tip would operate at. Each tip had a magnet on the back which attracted a contact inside the soldering
iron when it reached its set temperature and the magnetism within the tip would weaken on the
contact we would be broken. In the early days of my career I spent many hours using these
magnetic irons. They were very satisfying to use, the satisfying clack each time the iron
was returned to the stand, a smell of fresh solder and flux. The way the iron would lightly vibrate
and buzz in your hands for a second or so just before the thermostat clicked over,
how yes indeed it brings back happy memories.
These days very little is hand soldered, as I mentioned earlier it's becoming a bit of a dying
act. Modern circuit boards are soldered using wave soldering techniques. The components are placed
onto the boards using robotic pickers, circuit boards sit on conveyor belts and pass over liquid
solder, producing a complete fresh board in the matter of seconds. We had wave soldering machines
back in the early days of my career, but we also had assembly lines full of people hand soldering
components on circuit boards. After circuit board had been hand soldered, it would then pass to an
inspection person who would check each individual soldered joint with an eyeglass. Wave soldering
was only used on the less critical boards because the quality of the joints produced were not
as good as what could be achieved by the assembly workers. A few hand soldering irons we have within
the company today are used for quick lash-ups or perhaps attached to a wire. The humble soldering
irons has changed a little over the years. The changes mostly been down to the health and safety
concerns. Other remaining company soldering irons are fitted with suction pumps to remove any
fumes during a soldering process as these humours can eventually cause health problems. Also,
the soldering used these days is lead freeing. My trusty will or temperature controlled soldering
irons does not have a suction pump fitted and over the years I've used it for many hours,
plus I spent many hours during my early career using soldering irons without suction pumps,
and I've not encountered any health problems relating to my years of soldering.
I have an occasion used these new irons with suction pumps, but if I finally make the iron
clumsy and balanced and generally difficult to handle, so much so that when nobody is looking,
I generally pull the heavy rubber tube from the iron disconnecting it from the pump.
I'm sure any health and safety people listening would be appalled, but I'm happy to take this
chance. If you're really worried about this, there are simple things you can do to minimise any
smoke inhalation, such as holding your breath whilst making a solder joint and then immediately
looking away to take a breath. For the home hobby enthusiast, a soldering iron with suction pump
is overkill, and I certainly don't use one, but this is something you will have to decide for yourself.
If you suffer from asthma, then perhaps you should be cautious, but other than that, I'm sure you'll be fine.
Okay, now comes an important part. The rest of that stuff is just waffle in my part.
This is stuff that really matters. I would recommend my good quality, straight forward electric
soldering iron, one with a good quality iron coated tip, preferably temperature controlled.
If it needs to be used, whether it's knowledge or outlet, then buy a gas soldering iron.
By a soldering stand, they're very cheap and are just plain daft to balance a hot soldering iron
on the edge of a table. I know this because it's something I did for a long time until I learned how
to solder properly in the early part of my career. By a soldering sponge, this is absolutely essential
to keep the tip of your soldering iron clean. The sponge usually comes as a small solid block
that expands when water is added. The soldering sponge is special being made from
cellulose so it can withstand high temperatures. By multicore soldering, which is impregnated with flux,
tweezers can be handy for holding small objects. Small cutters are useful to trim the legs
and components and cutting wire to length. I said that helping hands can be useful,
I don't necessarily mean someone else holding things for you, although this is something
is also useful. What I'm talking about is a device that has a heavy base,
crooked up clips to hold items and magnet-fanged glass and perhaps a light to eliminate the job.
This can be very handy indeed and can save you from many a button finger.
An eyeglass can be especially useful, particularly if your eyesight is getting a bit duff like mine is.
It makes it easy to read values of components or perhaps to check for a dry joint or circuit board.
A dry joint happens when the solder feels to wet the metal and a bad contact is made.
A solder joint should be bright and shiny. A dry joint is usually a dull grey colour.
Dry joints may only become a part on a piece of equipment many years after its manufacture.
You might find that tapping the circuit board brings the circuit back to life.
This is a sure indication you have a dry joint somewhere in a circuit.
I'll put the link in the show notes about dry joints.
A solder circuit can be used for a component removal. A solder circuit is a bit like a small
bicycle pump. You push the plunger on the top of the device, hold it up against the joint
which you heat and then quickly push the button, sucking the solder into it.
Component removal can sometimes prove difficult and sometimes it is better just to cut the
leads in the component side and they heat them and pull the leads out from the top of the board.
The solder circuit can then be used to clean up the solder land ready for their placement component.
Heat shrink's leaving is very handy. It's usually in the shape of a plastic tube made from nylon.
The diameter of the tube shrinks when heated. Heat shrink's leaving is available on a huge
range of shapes and sizes. I find heat shrink's leaving extremely useful,
particularly when creating or repairing cables.
Heat shrink is usually shrunk into place using a heat gun. You can purchase heat guns
specifically for this job. Alternatively you can use a paint stripper heat gun.
However these tend to be little fierce and I would imagine great cave would be needed doing this.
There is another solution to this problem and I'll let you in on it.
I had the very same problem many years ago when I purchased a large bundle of heat shrink.
I wanted to put it to good use. I fully intended to buy heat gun but was either too lazy or too
mean to buy one. In the absence of a heat gun you can with a bit of care use a toaster.
Set the toaster them as that to maximum so it doesn't pop up while you're shrinking the joint.
I make sure to close the doors in your kitchen as a burning toaster male will set off any smoke
detectors you have. Once the toaster is warmed up carefully dip the cable in and out of the top
slot the toaster rotating it from time to time so the whole joint is shrunk.
Again I'm not sure how safe this is but with care it does work. I've done this many times in
the past. If you use this method do so at your own risk. Blue tack is a bit like plasticine
but a bit more sticky and is generally used to stick pieces of stationary onto walls as a replacement
for drawing pins. I find the particular hand of holding and locating small awkward screws.
It's handy when trying to refit a screw deep inside a recess allowing you to locate it deep
inside the screw hole. Small screwdrivers can be invaluable. There's a lot of high-tech gadgets
these days use tiny screws and often delicate clips holding the thing together and probably this
is the single biggest challenge you'll have repeating something these days.
Okay that's about it for this episode. Next time in part two I'm going to try and describe
the actual steps required to produce a good and consistent solder joint. If you want to give it a
go then be sure to gather together the essentials for part two which a promise won't take as long
to prepare as this one took. As a minimum you need a soldering arm, soldering arm stand, sponge,
not forgetting the single most important thing of all that is multi-core solder. A good
superior small work headers could also be handy. Show notes for this podcast and available at
HPR and we'll include the list of relevant links and further information. I can be contacted at
mrx at hpr at googlemail.com at mrxathtr the at symbol googlemail.com. Okay I hope you enjoyed
this podcast so until next time thank you and goodbye.
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