How to Solder

Step 1Tools and materials

Tools and materials
Soldering is the process of using a filler material (solder) to join pieces of metal together. Soldering occurs at relatively low temperatures (around 400 degrees Fahrenheit) as compared to brazing and welding, which actually melt and fuse the materials themselves at higher temperatures. In soldering the filler material becomes liquid, coats the pieces it is brought into contact with, and is then allowed to cool. As the solder cools it hardens, and the two materials are joined. Soldering is a quick way to join many types of materials, from copper pipe to stained glass. It creates an electrically conductive strong bond between components that can be re-heated (desoldered) if you should ever want to disconnect two items joined together. It's great for joining electrical components and wires and is used in just about everything electronic. In this Instructable I explain how to solder the basics you see in most Instructables: electrical components and wires.

For further information and some more technical specs on soldering check out the wikipedia article.

As with many skills, having the right tools for the job effects the quality of the work being done. When it comes to soldering you can end up using a lot of fancy tools, or just a few simple items you can pick up at the hardware store for a couple of bucks. I am going to use a couple of different soldering tools in this Instructable; there are many ways to solder, and you should use what works for you.

At the very minimum you will need the solder and a heat source to melt it - preferably something small which can get to 600-800 degrees Fahrenheit. If you've got that, your ready to make a connection. That being said, there are a wide range of soldering tools and accessories that can be really helpful if you're going to be soldering frequently. Ladyada has compiled a nice list of equipment and sources to buy the tools on her site. I got together a solid supply of soldering tools by raiding the Squid Labs soldering station. Here is the complete list of what I used...

1. Soldering iron
Most people opt for using a soldering iron to solder. It's a great heat source that heats up and cools down quickly and can maintain a pretty constant temperature. Soldering irons can be purchased from a variety of places. I have picked up some at Radioshack - evil yes, but convenient, some from the hardware store, some from garage sales and a bunch more from retailers online. Low wattage (15-40 watt) soldering irons work best for soldering components on circuit boards while more powerful (60-140 watt) soldering irons work well joining thicker materials like braided speaker wire. If you use too powerful of a soldering iron on a circuit board you might damage the components you are trying to join. I like to keep a low-wattage iron around for detail work, and a high-wattage iron that I can use when I am not too concerned about exposing the material I am working with to high temperatures. It's a real pain to solder thick wires without a powerful soldering iron.

The soldering iron in most of the pictures is made by Weller, and has a variable temperature control. This is the best of both worlds since you can set the heat exactly where you want it, but it's significantly more expensive than fixed-temperature irons. If you're just going to do some occasional soldering it isn't a must have by any means. Anyone interested in modding a soldering iron should check out DIY Hot Air Soldering Iron by charper.

2. Solder
There are lots of kinds of solder available. They come in different thicknesses from around .02" to some really thick stuff you would only use on copper pipe with a butane torch. You use thin solder for detailed work like putting resistors onto circuit boards and thicker solder for joining larger materials like speaker wire. I use solder around .025" for most jobs. Most solder is made from a combination of tin and lead - it's about a 60% tin, 40% lead mix depending on what solder your using. Recent international health codes from Japan and the EU (California and New York have adopted similar policies as well) mandate that lead solder be phased out of certain commercial products and substituted with a lead-free alternative. The manufacturing deadline was this past July so we should be seeing the changes now. Even if you don't live in California or New York its still worth staying away from lead solder since lead has been known to cause all kinds of a nasty health effects from birth defects to severe developmental and neurological damage. Plus it's pretty easy to find the lead-free stuff.

Some solder will contain a small amount of silver. This pushes the melting temperature up a bit, but the silver helps the solder to flow and makes a stronger joint. If you are worried about burning whatever your working with, try to stay away from solder with silver in it, but it works very well if you're just joining wires or something that won't be easily damaged. The last thing to know about solder is that you want to use a solder that has a rosin core. The rosin acts as a flux when soldering and helps the connection - it's also the kind that's most readily available at the hardware store and from electronics suppliers.

3. Soldering iron tips
Soldering irons come with a tip, so you don't have to go out and get a special one, but it's important to know the differences between them and make sure you're using the right tip for the kind of soldering you're doing. Some small-wattage irons come with conical pointed tips for detail work, while most high-wattage irons come with a flatter screwdriver-style tip that works well on wires. You want your tip to be a little smaller than whatever you are soldering so you have good control of what you heat up and what you leave alone.

4. Soldering iron holder and cleaning sponge
It's nice to have a safe place to put the soldering iron down in between soldering. A soldering stand safely holds the iron and gives you a place to clean the tip. Some soldering irons come with their own holders. If yours doesn't have one, you can buy one or make one. jaime9999 has a Homemade nearly-free Soldering Iron Stand that is pretty much identical to what you can buy. The stand isn't a necessity for learning how to solder, but it does help.

5. Tools to work with wires
I have a go-to stock of tools that I round up when working with wires or electrical components. They consist of wire cutters, a wire stripper, needle nose pliers, and an automatic wire stripper (courtesy of the Squid Labs soldering station.) The automatic wire stripper is really convenient if you're going to be stripping lots and lots of wire, but by no means necessary. I have stripped lots and lots of speaker wire using my teeth (not the best idea, I know I know.)

6. Clips to hold your work
Often called "third hands" or "helping hands," these little guys help a whole lot when soldering. You have to hold the soldering iron with one hand and the solder wire in the other, so it really helps to have something else to hold the components you're actually trying to join. You can use alligator clips, clamps, or even some tape to hold things in place if you need to. The third hand is generally a good investment if your going to be soldering regularly, and there are plenty of Instructables with with ideas to modify them if you do happen to pick one up. Check out: Make a 3 degree of freedom 'hand' to help with soldering / gluing work and make your 'helping hands' 100x more useful for soldering / gluing small parts by leevonk to start.

If you would like to make a set of helping hands of your own there are already a number of good Instructables on that too. Quick helper for surface-mount soldering by http://www.instructables.com/member/bikeNomad/bikeNomad, QuickMods - Soldering Arms by Aeshir and Build a Pair of Helping Hands by john otto should get things started.

7. Exhaust fan
I do most of my soldering at a soldering station that is equipped with an exhaust fan. It's really not such a good idea to breathe in solder fumes, and soldering does produce fumes. Any kind of ventilation/fan you can rig up will help. Vent the fumes outside or use an indoor fan with a filter if you can't vent them outdoors. Here is a Window-mounted solder fume extractor (not just for RVs!) posted by bikeNomad. Also check out Dr. Solomon's low tech, but functional Solder Fume Extractor if you're looking to build something that you can place right on your table. If you're just doing a quick soldering job, the fumes wont kill you by any means. I have certainly done my fair share of soldering without a vent, but anyone doing repetitive soldering should definitely pick one up or make one.

8. Safety goggles
I hadn't ever used goggles before while soldering, but while doing research for this post I saw it mentioned elsewhere and agree that its a good idea. Little molten bits of solder tend to fly out of the soldering joint when you're feeding in the solder, and if it landed in your eye it wouldn't feel too good.

9. The materials that you want to join together
I was just messing around, and mostly soldering for the purpose of this Instructable so my materials didn't necessarily make anything. You can solder wire, electrical components like resistors and capacitors, circuits, breadboards, electrodes, small pieces of metal and whatever else you can think of. Don't know if it can be soldered? Give it a try - you won't blow anything up.

Once I have got my tools and materials rounded up, I like to pretend that I am a pilot and begin my pre-flight/solder checklist.
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21 comments
Jun 26, 2010. 7:28 PMPercivilis says:

Hi! First of all, thanks for the very clear, very instructive 'ible! I'm just starting to solder components onto circuit boards, and it's been very helpful. I have a quick question, though, regarding materials.

I'm soldering components onto a PCB, and I'm currently using a 15-30W iron from RadioShack and 0.022" lead-free solder from the same. I'm trying to use the "Through Hole Component" method from Step 4, but I'm running into some trouble. I'll turn the iron to the 30W setting and hold it so it's touching the copper contact on the board and the component I'm trying to solder in, and then hold the solder up... But most of the time, nothing happens, even after a few minutes of me sitting there, holding everything very still. I'm heating it up enough for the copper on both the wire and the board to oxidize and turn black, and then some, but my solder's just not melting.

This isn't always the case... It's worked before when soldering in a voltage regulator and some copper wire (although each of them took about a minute of direct contact to melt the solder), but I've just spent the last 30 minutes trying to solder in the other end of the wire, to no avail. Do you have any idea what could be causing this? Is my iron not powerful enough, perhaps, or is there probably something wrong with my technique?

Any help would be very much appreciated. Thanks in advance!

Feb 5, 2010. 6:39 PMInLiquidWonder says:
 I can't find a good suggestion (thanks for nothing, Google) for what table surface is best for soldering projects.  I don't plan on dripping all that much solder, but I want to know what common household surfaces are safest for my projects without incurring damage to the table surface.  I'm open to picking up a mat as well, if anyone recommends one.
Jun 16, 2010. 1:47 PMpfred2 says:
I use a quarter inch thick stainless steel plate. It seems to hold up OK.
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Mar 22, 2010. 8:07 PMstatic says:
I'm thinking for most of us protecting our bench tops from soldering work isn't that critical. Any slight damage is certainly going to add the character of the shop. :) But seriousily the Formica surface of my old desk hasn't been hurt by hot solder that has ended up on it, though it has been subjected to large blobs of hot metal for any apprecible amount of time
Mar 21, 2010. 10:24 PMsockless says:
Use a piece of cardboard, an old plank or a newspaper.
Mar 21, 2010. 12:36 PMAzayles says:
Use a large glass or marble chopping board/work surface for the kitchen. The ones used for preparing pastry are idea as they tend to be bigger. Glass ones will be toughened, so you don't have to worry about it breaking from heat or minor impacts.
Jun 29, 2010. 10:47 PMnemaster203 says:
Solder almost always has lead in it, are you suggesting eating lead is healthy for you? I'd just use a piece of plywood big enough for what I needed to solder on top of any surface.
Jun 30, 2010. 8:07 AMAzayles says:
I'm nut suggesting you solder in the kitchen, or use a kitchen work surface than you're then going to use to prepare food on. I'm suggesting buy a new chopping board, use it for soldering only in the workshop and not for food use. That should be common sense, which is why I didn't state it in my previous comment.
Mar 21, 2010. 11:30 AMvanmankline says:
I use some scrap steel plate that came from the door of an old oven.  An old kitchen trivet or sheet pan may work well too.
Mar 21, 2010. 10:33 AMzack247 says:
may i reccomend a glossy ceramic tile? they stand up to the heat well, and the glossy coat doesn't melt and the solder comes right off. (if you drip some)
Apr 12, 2010. 11:27 AMiturnem says:
Just wanted to give a tip for applying flux that i find works better and has less waste than using a qtip or something similar. I take a piece of stranded wire and strip about 1/4" back, then fray the strands out like a brush and use that to spread solder on component, pcb etc... Much less is wasted because it doesnt soak up excess amounts of flux when dipped in.
Jun 16, 2010. 1:08 PMpfred2 says:
More often than not I'll just grab a small slotted screwdriver to apply flux with. Sometimes I'll hit a dry connection with some fresh fluxed solder to get it flowing again too. Depending on my mood, and the job I have to do. Preheating what you want to flux can help flow a thin layer as well. The less flux you use the better. Do you use liquid flux? I use rosin paste for electronics myself. The liquid brush on stuff is for sweating pipes!
Jun 3, 2010. 9:33 PMraja681 says:
im fairly new to soldering and im soldering outside do i still need a fan
May 23, 2010. 10:38 AMD5quar3 says:
 I have the same cheapo soldering iron it works fine for what I am doing.
Mar 31, 2010. 7:22 PMzombiehunter96 says:
Hey, Im fairly new to soldering. THis will sound dumb, but will soldering wire to a 9v be safe? I just dont want any explosions (beautiful as they may be) close to me :D
Apr 3, 2010. 1:20 AMmicobanff says:
No! Don't solder directly to a battery, buy a snap connector, you can get them in multi-packs, but I would recommend going to your local surplus store! Otherwise, http://www.radioshack.com/product/index.jsp?productId=2062218

You can always de-solder them or cut the wires to reuse it!
Feb 15, 2010. 10:01 PMspaztec says:
"You can even use a piece of sand paper, a file, or a powered grinding wheel to shape the tip of your soldering iron into whatever works best for you."

Nope. Don't do that. Worst thing you can do. You damage and scratch up the electroplated tip.
Mar 21, 2010. 8:35 AMmkanoap says:
I second this.  Soldering iron tips are generally copper coated with another metal.  This is because copper oxidizes faster at high temperatures and will basically rust away if kept hot and exposed to air.  The coating protects the copper from this happening.

Shaping the tip will expose the copper and lead to corrosion.

If you have a really old soldering iron the tip might be uncoated copper, in which case the tip can be shaped.  Such a tip should alway be tinned (not just the first time) whenever you are finished with it.
Feb 15, 2010. 10:04 PMspaztec says:
 Wattage doesn't necessarily mean that the soldering tool has a higher temperature either. Higher wattage allows the tool to better retain heat.
Feb 23, 2010. 10:06 PMurbanprimate says:
Well done!  I wish I could've read this 10 yrs ago, it might've saved me a lot of headaches!
Jan 10, 2010. 9:10 AMrkr says:
60/40 solder is the only way to go in my experience. I say if you're worried about breathing fumes or handling lead, open a window and wash your hands.
Jan 25, 2010. 2:28 PMcdousley says:
Thats what i use, its good stuff
Nov 13, 2009. 7:15 AMshadowsniper918 says:
i noticed u have the same exsact soldering gun as  me ( 100-140 watt) and it has a good tip i need a tip for mine really bad where do u get urs from ? is available online ? 
Jan 26, 2009. 12:07 AMcabie62 says:
Flux. Where's the flux ? It's one of the most important items needed when you solder. It can help you make a joint faster and it can also help keep the tip of your soldering iron clean. If your soldering iron looks like the one I saw in the first photo, your going to have a hard time transfering heat to the solder and to the components you are trying to soldet. The tip is supposed to look like the melted solder. It needs to be clean and wheeted if you want good, fast joints. The same goes for unsoldering a component on a printed circuit board. Have you ever wondered why sometimes it seems that you cann't get the solder to melt ? Well now you know why.
Jul 10, 2009. 8:29 AMweasel999 says:
For $3 in Harbor Freight Tools I found a "third hand" that has alligator clips gripers+ a magnifying glass attached to it . Heres the link
May 21, 2009. 5:40 PMTyMan210 says:
The picture shows it is "Rosin Core".
That means the flux in Inside the solder.
Jan 27, 2009. 9:43 PMrevhead says:
you seem to know what you are talking about so could you please answer my Question? I just brought a 60Watt soldering iron and as soon as I plugged it in a waited about a minute to let it heat up, when I looked at the tip it went from nice and shiny to completely black!! I tried a wet spung to clean it but had no success, and solder will still melt but it wont stick to the tip, it just balls up and rolls straight off the side, can you tell me why this happened, how to fix it, and has this damaged my soldering iron tip?? thank you!!
Mar 9, 2009. 1:53 AMcabie62 says:
sorry it took so long to get back to you. Sounds like you need to either sand off the black with some fine sand paper. or you could use a wire brush to get off the black. Do this with the power off ofcourse. then when it's nice and shinnie dip it into some Rosen flux, dip just the tip upto about 1/2 " should be enough. then plug it in or turn on the switch and let it start to heat up. It should start to smoke in a minuet or two then start trying to tinn the tip with some rosen flux solder. when the solder starts to melt on the tip start going althe way around with the solder. If you start to get too much solder on the tip just wipe it off on the spounge and go back to tinning again. keep this up untill you have a nice coat all the way around the tip. then you'll be good to go for a while. try to keep the tip wiped off on the spounge. that way you don't have to start all over again.Eventually you will have to though - this is a neverending cycle, but it is the only way you are going to make good joints without overheating the components. best of luck Cabie62
Mar 9, 2009. 10:53 PMrevhead says:
thanks. where can i get some rosen flux? what does it look like, is it like a liquide in a jar, or does it look like regular solder?
May 15, 2009. 9:28 PMScottydroid says:
Have you ever seen Petroleum Jelly? It looks very similar to that; its a sort of gel type substance. Though the case just looks like a small, white, can; reminiscent of a can of chew.
Jan 20, 2009. 1:31 PMeverywhere says:
(removed by author or community request)
Jan 30, 2009. 3:29 PMste5442 says:
Metcal irons are probably the best you can get hold of (if you have the spare cash). We use them at work in the lab - not much to look at but you can tell the difference in use. They also have a nice short tip/shaft.
The irons in this instructable look terrible - except the Weller which is always useful for the larger work!
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Feb 25, 2008. 11:54 AMdUc0N says:
There is one other consideration that needs to be made when choosing between a soldering iron or a soldering gun. Because of the way the tip is heated in the gun, they tend to heat up a bit faster, but almost all of them carry some current through the tip itself. Be aware that this current can damage or destroy some delicate electronic parts! As a rule of thumb, if it came in an anti-static bag (they're silvery or pink usually, and have a warning label similar to the one in the picture) then do NOT use a soldering gun! Some of the really nice soldering irons (Weller, for example) have grounded tips as well, for extra safety. The only other piece of kit I keep handy for computer work (where most of my soldering is done) is an antistatic wristband. These can be had for around $5, and there are versions that are connected to the ground of a power outlet, as well as a version that uses a capacitor and resistor sealed inside for freedom of movement.

Of course, none of this really applies with *basic* soldering (like for speaker wires, 'beginner' hobby kits, etc.)
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Sep 9, 2008. 8:44 PMLinuxH4x0r says:
If you have a gun like I do you are only heating it for short periods of time heat ip up off the components and then apply it while it is still hot.
Mar 19, 2008. 11:23 PMmitch_mason77 says:
Does anyone have a suggestion for places to buy solder online or household items i can use for solder? (i live in a small town with approx. 500 people and no access to a major city so hobby shops and electronic stores are not really an option)
Apr 30, 2008. 8:29 PMschetleft says:
try http://www.radioshack.com or http://www.ebay.com

i get everything from these places!
Apr 22, 2007. 7:52 AMkwalian says:
The Weller variable temperature soldering iron looks like a mini welder!(-:

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