One of the current threads in the Electronics and DCC forum asks what soldering irons are the best. I made the point that it doesn’t matter how good your soldering iron is if you don’t use the proper technique. I that post I offered to share my soldering process if people were interested, and Brent (Batman) suggested that I start a thread on the topic so we can tell others what works and what doesn’t work.
I won’t repeat the discussion about which soldering irons or stations work the best, but for the record, I use a Xytronics soldering station like this (photo compliments of Brent). It works really well:
I run my iron at 700 degrees. I have already tinned the iron if the tip is new.
Here is my method:
Apply a tiny amount of flux to the wire and the pad to which the wire will be soldered. Ngineering sells flux that does not need to be cleaned off after soldering;
Clean the tip of the iron. That’s what the brass sponge is for. Eventually the sponge will start to look dirty and you will need to replace it. Otherwise you will start to pick up impurities from the sponge. I clean the tip of the iron constantly, literally every time I pick it up;
I’ve never needed flux for my electronics soldering. I get good results tinning the wires and the pads. Maybe someday I’ll try it. Keep the tip clean and tinned and you shouldn’t have a problem. Have a little piece of Scotchbright handy for giving the solder pads a few swipes to clean off any oxidation if needed.
About the only problem I get is forgetting the shrink tube on the wire first. Or soldering the LED backwards. When you get old and you don’t do it often enough, you forget which side is the cathode.
Pete.
P. S. I’ve seen some horrible decoder installs even by professionals. Too much wire stripped off the end is a big one. Not good to have a half inch of bare wire soldered on a pad. Or a giant mass of wire. Fixed a club members locomotive that the dealer installed the decoder. Masking tape around the wires instead of heat shrink.
I’m curious to know what type of solder you are using. I use Kester 44 resin core solder with a 63/37 ratio, 0.030" dia. I don’t know how old the spool is, but it came from my dad’s workplace when he left there around 1968.
I can solder with it without applying extra flux but I find things go much quicker and much more reliably with a tiny bit of flux added. Every joint flows almost instantly and I rarely have a ‘cold’ joint despite my shaky hands which make soldering sometimes very difficult.
I use a rosin core .015 solder from Radio Shack. I don’t know specifics but I have two spools one not even opened. I also use a .032 for the big wires under the layout. Works good for me. After hundreds of decoders and a couple miles of buss wires and hundreds of feeders, I’ve probably used twenty to thirty feet of solder all told. I probably waste a lot because I’ll burn off about an 8 inch piece instead of working off a spool.
In your thread you mention that you are using a “cheap Chinese knockoff” soldering iron, and that you find the temperature difficult to control. I urge you to try the Xytronic soldering station! If you buy it from Amazon and you are not happy, you can return it.
For me, buying the Xytronic iron was almost like an epiphany! I had been struggling with the Weller unit that I had and was almost resigned to the apparent fact that I wasn’t good at soldering. It turned out that I was not a soldering klutz.
i use an inexpensive (~$20) soldering iron and rosin core solder. my soldering iron has an adjustment, but it is just a resitance that controls the current to the tip, not a temperature setting. It’s set about 60%
i find no need to use solder paste except when soldering larger wires. i believe the soldering paster provides a greater heat conducting path between the tip and metal when melted.
i don’t use a sponge or brass ball, i just use a napkin lying around to clean the tip when needed. i sometimes use my fingers
the tip remains tinned, so i find no need to add solder to the tip before soldering
i usually tin both pieces before soldering them together
i use a lap splice to solder wires together or to component leads
when applying solder to the joint, i wedge the solder against the tip and joint so that the solder melts directly on the tip and once melted further conducts heat to the piece being soldered
i try to use as little solder as possible. my understanding is the solder allows a chemical bond between the piece of metal where they are in contact with one another, it is not a mechanical bond like glue
i try not to breath the fumes that come up when soldering, blowing them away from my face
I’ve had my Weller soldering station for a long time. No problem with heat control. Sometimes I might hit the temp control knob by accident, but other than the large footprint on my little bench it’s been very good.
My soldering iron is so old it has a cloth covered cord. The bulb burnt out decades ago and sometimes the trigger loses contact between the first and second stage. BTW. It’s 150/250 watt.
For soldering LEDs I took this paint edger, cut off the ends, and screwed it to a scrap piece of hardwood floor. I can put several LEDs underneath the edge of it to hold them and solder away. I just turn them around to do the other side. Doing many at the same time sure speeds things up. I have a tin full of wired LEDs ready to go. I need a light somewhere it is done.
The first time I needed a lot of LEDs was for my RH and I thought how would Henry Ford have handled this?[(-D]
That is a property of eutectic solder: Its freeze and melt points are almost the same. As soon as the heat source is removed it will freeze.
A little flux never hurts. I’ve got all kinds of solder on my workbench at work, who knows how old it is. Some may even be war booty [:)]. Needless to say it doesn’t work very well, and can be frustrating to use.
Even more frustrating is engineers and physicists saying you don’t need flux when the result indicates otherwise.
That’s the sort of iron (soldering gun) that I use for track work, and mine works great for heavier jobs like attaching feeders and soldering rail joints.
The Weller that I used previously was a pencil tip style so we are talking apples to oranges. However, before my hands started to shake I could use my soldering gun on delicate stuff, but shaky hands put an end to that!
My point exactly! Yes, obviously lots of people can get away without using flux and I’m not being critical of their work at all. I just find that by using flux I almost never have a joint fail, and when I do have a faulty joint it is almost always related to the difficulty that I have holding my hands still.
One factor that I think comes into play here is the amount of soldering experience that people have. I would be willing to bet that those who don’t need to use flux have done a lot of soldering. My method is aimed at a person who is just starting out and who has no experience, or who has had bad experiences. Once you have some experience under your belt, you can experiment with not using flux, but I strongly advise newbies to get your soldering down pat before starting to eliminate steps in the process.
The solder that I use is more than 50 years old and it does have a rosin core, but I don’t rely on the rosin in the solder to get a clean joint. That’s why I add a bit of flux when I am tinning a wire or a pad, and again when I am about to make the joint. It works for me.
Thanks for sharing your knowledge of the soldering process! I have learned a thing or two.
when I use my old rosin core solder without any additional solder paste, i first see the rosin melt and flow over/into the metal surface/wire and the solder flows as well.
The “basic” solder to use for electronics (when you don’t care about soldering multiple pre-soldered assemblies – I’ll get to that – IF you can tolerate exposure to lead is the mentioned 63:37 (as in Kester 44). It is a eutectic, which is a fancy word meaning that it freezes ‘all at once’ as it starts to cool, instead of forming a slush like 60:40 can.
The recommended electronic solder in the first post is better. The principal reason for that 2% of silver is that when you solder to pads plated with precious metal, some of that metal dissolves in the solder. In jewelry soldering (where the stuff comes from) you want to avoid any migration of silver from the pieces being joined to the joint, so the solder ‘preloads’ the amount that might have dissolved. (At this point you should be thinking ‘well, if I solder to gold pads, shoudn’t I have a trace of gold in my solder too?’ and the answer, well, is yes but we don’t need aerospace-grade perfection.
There are solders with higher and lower melting points. Many modelers will have used or tried Tix solder, with its special required flux. There are even lower-melting solders (you can google indium-bearing solder for some of the temperature ranges). For structural instead of electronic work you can use higher-melting silver solder (not 2% but higher, as a structural constituent) which is also stronger than typical tin-lead, and if you fabricate subassemblies with this, you can do final assembly with tin-lead eutectic without nearly the heat-sinking fun you’d have trying to do it all with one temperature…
I too recommend the Xytronic station… BUT I’d go ahead and spend the extra money on one that (1) has digitally-displayed temperature control that you can in fact read while working; (2) also includes a vacuum ‘solder sucker’ for removing solder you no longer want in a joint; and (3) has a hot-air gun for solder ‘reflow’ work
Dave, nothing I can really add to what you and others have already said. I pretty much follow the same procedures. I too have an Xytronic 389 and couldn’t be happier. I also tin the tip and both surfaces to be soldered. The only thing we differ in is I don’t use flux. Not saying it’s not necessary or not beneficial, I just have never used it. I have no doubt that it probably is beneficial for sure.
I got into the habit of using flux before I got my Xytronic unit. I was using a Weller soldering station at the time, and as I have mentioned before, I was having a lot of trouble keeping the tip clean and tinned. The flux compensated for that to a certain degree.
In hindsight, I should have realized that the tip was burned out by the way it was behaving, but the tip had not been used very many times. I guess I didn’t want to admit that it was just a piece of junk. I was brainwashed by the Weller name.[D)]
I’m going to continue to use flux because it makes the process so quick and easy for me. All I have to do is touch the joint and the solder flows instantly, and I don’t have to worry about the tip moving around if my hands start to shake.
There is an iron plating on the tip that can wear off. Once the copper beneath is exposed, the solder will erode it as it alloys with the copper. No big deal, you just get another tip.
Acid flux does no favours there. TIX is a known offender. Acid fluxes are meant to be used with a torch providing a lot more heat to activate it. In time they will damage the iron plating.
Aggressive cleaning will also remove the plating, so no files or sandpaper. A paper towel is very effective for cleaning the tip. There are also tip rejuvenators available the clean and condition the tip. The one I have is from MG Chemicals.
I was taught that it’s the film of solder on the tip that maintains things ‘clean and bright’ and that you can work quite effectively with a plain copper tip (which is easy to file to shape as needed, which you can’t do with a plated tip) as long as you maintain strict tip-cleaning and retinning discipline. It’s when you starve the tip to the point the copper oxidizes that you get problems. If that happens, you carefully clean the tip down to bare copper, polish the copper, and re-tin with flux until it is tinned smooth and bright again.
The tip is copper for the same reason British inner firebox wrappers are copper: better heat transfer. The plating on a tip actually impedes good heat transfer. Where the ‘problem’ comes in is when you have a plated tip that starts to lose its plating – when that happens you either strip off all the plating and observe correct tinning discipline, or replace the tip with a ‘new’ one. Tinning and cleaning will be a pain otherwise.
