Instructables

How to solder - the secrets of good soldering

Picture of How to solder - the secrets of good soldering
I have seen lot's of advice given to people on soldering electronic components, some of it good, some not so good. I have seen people use all sorts of rubbish and claim it does the job, $2 soldering irons and other crazy stuff. Yeah you can melt solder with it, and you can probably get a few acceptable connections sometimes. But if you want to do it the right way, consistently, without fighting the iron, and get proffesional results, read on.

If the instructions given in this article are followed carefully, even someone new to soldering should be quite competent with a few minutes practice, it's really not difficult at all. If you dont want to take the time to read all the details, I have put the main points in bold at the end of each section.
 
Remove these adsRemove these ads by Signing Up

Step 1: Soldering iron

Picture of Soldering iron
Of course the first thing you need is a soldering iron. You don't need to get anything too fancy to get good results, but if you are going to use a soldering iron more than a couple of times it is worthwhile getting something half decent. There are lots of so called cheap 'temperature controlled' soldering irons on the market these days. Most of these are not really temperature controlled at all, they have a knob you turn which reduces the heat of the iron, but a real temp. controlled iron will set you back a couple hundred bucks for a decent one. There's nothing wrong with some of these irons, but do you really need an 'adjustable' iron?

My advice would be to spend your money on a good fixed temp. iron, it will probably cost you at least as much, even a bit more than one of the cheap adjustable temp. irons. You can always build a temp. control unit for your iron later if you want. You don't need adjustable temp. to do fine work though, if you put a smaller tip in an iron it doesn't transfer as much heat, and most people will only want to go to a fine tip if they are working with surface mount components, and even then some wont go to a fine tip.

The iron I like is the one in the photo, it's a 'Goot' made in Japan, has a ceramic heating element and will go from cold to ready to solder in under 30 seconds. This one is actually 46W and most people will want something around 30 to 40W for general work. But I love the control this iron has, I can solder the most delicate IC and go straight to heavy gauge lugs with the same set-up.
I think some people use underpowered irons with very fine tips, thinking this will be delicate, but end up holding the iron on the part for half a minute to get it to solder, and still get a weak joint. You should only have to hold the iron on something like an IC pin for about 2 or 3 seconds.

If you switch to a fine tip because you want to neaten up your PCB work, for example you're getting solder bridges between pads or IC pins, you will probably find it doesn't help very much. Instead you might find yourself having to hold the iron on longer because it wont heat up enough, and the solder wont flow properly. The tip probably isn't your problem, and you might find switching to thinner solder will help more. Using thinner solder makes it much easier to control how much solder you feed into the joint, if you are using around 1mm diameter solder, try switching to about 0.5mm diameter, but keep the normal size tip.

To sum up: Get a decent soldering iron with the right size tip.
lepak474 months ago

actually if your lead free melts at a lower temp then the 60/40 then the tensile strength will be significantly less then the 60/40

dkeach10 months ago
Actually, unless I've been repeatedly lied to, lead free solder actually melts at a lower temperature than lead bearing solder. I am not a novice and have been soldering since age seven when my dad and I built R/C cars, but I wouldn't say I'm an expert either. I've got to say though this is a very educational and thorough how to. This can be a fun skill to have and s painful lesson to learn occasionally
Great instructable!
My favorite soldering irons are temperature controlled soldering irons with digital display. It is possible to set very accurate temperature on tip of soldering iron. My favorite models of soldering irons are Weller WESD51 and Weller WES51 (WESD51 has digital display to show temperature of the tip). There are some reviews about temperature controlled soldering irons here:
http://www.soldering-store.com/
Nice Instructable. quick question, can you give a link to where to buy the soldering iron (from Step 1)  you have some from someplace in the US. or some place that ships to the US
www.sparkfun.com
440hertz (author)  mitpatterson4 years ago
Thanks, but I am in Australia so I don't know where you would go for that particular soldering iron. I'm sure it would be available though.

FYI its a GOOT brand of iron, they are made in Japan, its 46Watt which I find is a really good general purpose type iron. The tip maintains its preset temperature well and its safe to use on sensitive parts, I have used it to solder everything from big chunky contacts to very small surface mount components no problem.

Here is a link to the Australian version http://www.jaycar.com.au/productView.asp?ID=TS1430&keywords=goot&form=KEYWORD
it is a 240 volt model, But I'm sure you can get 110V models. There are other brands which are good, I just think you are better off spending money on a good quality fixed temp. iron instead of getting a lower quality iron with adjustable temp. The problem with some of the cheaper variable temperature irons is that they don't actually maintain their set temp. very well, plus they dont allow you to set a prticular temp. but rather just vary the temp. up and down by varying the power.

So if you adjust the temp. down and it is at say 280 degrees, ( you wont know what the temp. is unless you measure it with a thermometer) you start soldering and the tip cools down as you are working to say 180 degrees and now it isnt hot enough. You might actually have to stop soldering for a while until it heats up again. With a good set tmp. iron the tip is set at an optimal temp. say 320 degrees and the iron tries to maintain that temp. all the time. The heat recovery is so good that you don't even notice the iron cooling down. 

Of course you can get good variable temp. irons that have great recovery, some even allow you to set it to an exact temp. but they are very expensive.  I just think if you wanted to spend say 50 bucks you would be better off putting that money into a good fixed temp. iron rather than a cheap variable temp. iron. Also if you really want variable temp. you can always build your own temp. controller for the fixed temp. iron later on. A quick way to cut the power to the iron down is with a diode, this will 'half' rectify the AC power and give you a little over half the power to your tip. Chuck in a switch and you have a 'two temp' iron, a kind of 'high/low' setting, which could also be used for 'standbye' to possibly increase tip life by running it on lower heat but having it almost instantly ready to use when you want it.
i already made my self a sorta temperature controlled thing, i use3d this guy's advice ( www.afrotechmods.com/cheap/iron/iron.htm ) hes kinda crud in his writing but the basics are there, and it actually works
thethomas982 years ago
Good soldering irons for the price:
I am a maintenance technician at a manufacturing plant just breaking in to playing with electronics. I have purchased a few soldering irons and have found for the price if you are just getting in to soldering period Weller is a good brand of irons to use. They are priced any where from $30 all the way into the thousands for professional setups. I myself purchased a Weller WES51 and haven't regretted it since.
Thanks so much for the detailed info. I'm just getting back to having fun with electronics after 20+ years away, and am doing chr's 8x8x8 cube. I didn't read this until the 5th layer of the cube. Buh. Now finding it very easy to get the joints to work first time.

Thanks!
About lifting pads:
The copper is held to the bpard by a glue. The glue loses ~80% of its strength while it's at soldering temperature. To avoid lifting pads, never push on the board with your iron. Giving the board mechanical stress _while it's how_ is almost guaranted to lift a pad.
When the board cools down, the glue should retun to its usual strength.
techno guy3 years ago
For the scouring pad, could you just use steel wool?
No, and here's why: Copper conducts heat very well, but it is soluble in solder, so iron tips are made of copper and coated with a thin layer of iron or nickel (which won't dissolve). Steel wool will scratch off the iron or nickel, and the tip will start to dissolve. Brass wool scouring pads will work, however, because brass is relatively soft (as metals go), so it won't damage the tip.
amclaussen4 years ago
Thank You for a helpful Instructable!

May I suggest that you include some description on the 63-37 solder.

I've never understand why the hell the solder manufacturers bother making the 60 Sn-40 Pb (tin-lead) solder.  It is plainly stupid since Tin is a little MORE expensive than Lead...

But 63-37 solder is what is called Eutectic, which means it has a SINGLE fusion temperature (183 °C or 361.4 °F) that is the LOWEST temp of all the In-Lead alloys.  This means that the melted solder solidifies instantly, which greatly reduces the possibility of bad joints or "cold solders", and also reduces the risk of damaging delicate components.  Since all solders containing Lead are being phased out by the almost crazy inflated worry about Lead, it is a very good idea to buy a large (by amateur standards, that is) quantity before it becomes unobtainable.
Regards.
Alfredo M Claussen, Mexico City.
It may have a single fusion temp but the solder won't solidify instantly cos' it still has to cool down to that fusion temp. and as for the price
big quantities X(times) little bit of money = alot of money
But good point about stocking up though.
Sorry for the TYPO...  I mean "Tin-Lead" not In-Lead...
amclaussen4 years ago
Ahh, I almost forgot to say that I have tested and compared both 60-40 and 63-37 solders, and the difference is easy to spot.  Really recommend the 63-37 as the only one to use (unless you have special needs, like more mechanical strenght, which can be had by using 96-4 Tin-Silver, but not for electronic work!).
amclaussen
UbuntuNinja4 years ago
Here are some techniques I have found useful when using lead free solder: -make sure the tip of your soldering iron is well tinned with solder but does not have to much solder or else solder flows onto the iron not the joint -if the solder is not flowing onto the joint after holding the soldering iron on it for several seconds, especially if the metals are starting to change color because of the heat, take the iron off the joint and make sure it is tinned well because holding the iron on the joint to long will cause oxidation
cupofsoup5 years ago
thanks...........from panhead
AndyGadget5 years ago
An additional tip :- If the copper-clad board you're soldering to has been lying around for some time the surface will have oxidised and will not take solder well. Give it a scrub over with a bit of fine emery or the brass brushing wheel of a dremel tool to clean it up.
AndyGadget5 years ago
Nice guide. I'll be referencing this in my future Instructables. I totally agree about the 60/40 tin/lead. A few months ago I came the the end of a 5Kg reel which I'd been using for (literally) decades. I bought some of the new 'safe' solder and started to use it. I was initially wondering if the iron was running cool as I couldn't get the damn stuff to tin properly. You can still get the good stuff, but stock up while you can.
Thanks! I've got a couple of projects ready to move from the breadboard to the circuit board and have been procrastinating because of soldering issues. With a little practice following your instructions I have less hesitation about going for it. Jim
Nice instructable! Good explanation of oxidation.