Instructables
Picture of Circuit Building 101
finished.jpg
This is a beginner's guide to building circuits that will talk about the "proper" way to install components (resistors, ICs, capacitors, etc), and also a little bit about soldering. It'll cover things like recommended tools, how far and which direction components should be inserted, pre-bending and clinching leads along with some tips and tricks. We'll be using a power supply kit made by David at uCHobby.com that plugs into a bread board for demonstration. Yep, we're commercial and sell all this stuff, but the advice should apply equally well to anyone's tools and circuits.
 
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Step 1: Recommended Tools and Supplies

Picture of Recommended Tools and Supplies
- Soldering iron and solder: Just about any 25-30 Watt soldering iron will do. Ideally, the temperature of you iron would be between 600-700 degrees F (for lead-free solder, 700-800 is recommended). How temperature relates to wattage depends a lot on the iron (watch a video testing the temperature of cheap RadioShack irons), and some high wattage irons have too high of a temperature. Avoid "solder guns" as these are meant for pipe soldering. Not only can these be too hot, but they work by running high current through a resistive heating element, and this could apply dangerous voltages to your circuit.

For solder, we recommend starting out with a lead-based solder, usually called 63/37 (63% tin, 37% lead by weight) or 60/40 rosin cored solder. Get whatever's cheaper; there's unnoticeable difference in hand soldering between 63/37 and 60/40. The rosin is a flux that cleans parts so solder will bond with them. Avoid solid wire (no flux core) and acid cored solder (for plumbing, too aggressive for circuits). We recommend solder that's about .031" in diameter for most through-hole components. Water-soluble flux is much more aggressive than rosin, and these residues must be cleaned. Lead-free solder melts at a higher temperature, and doesn't wet or spread out as readily, so it will be slightly harder to use.

- Needle Nose Pliers: Useful for pre-bending leads, pulling out components during de-soldering, and a lot of other things.

- Wire Strippers: Two types are shown: the yellow ones can be adjusted to strip any size wire (good for small 28-30 AWG ribbon cable wires) whereas the red handled ones have several fixed hole sizes.

- Flush Cutters: Used to trim leads close to the board after soldering .

- Clamps: Oftentimes just resting your board on a table will be fine, but the clamps are especially helpful when desoldering parts or soldering wires together.

- Solder Sucker and Solder Wick: Both are inexpensive ways to remove solder. The sucker is a spring loaded tube that vacuums out solder and the wick is a fine braid of flux coated copper that soaks up solder.

- Multimeter: Some multimeters have a continuity check that beeps if there is a complete circuit. This is very useful for making sure parts are connected or disconnected when there're a lot of wires and parts.

-Pink Erasor: (not shown) A pink eraser can be used to rub off oxides from older components and boards without risking damage to the parts.
LionBlood9 months ago
I want to learn how to make one. How do I make my own circuit, I don't understand how
mscharf1 year ago
Does anyone know a way of turning on and off a single led using a ir remote? What doe I need? I was thinking of some how connecting the led with the appropriate resister along with a IR Receiver Diode and some kind of switch and a power source, how would this work? Is this all I need? any and all help is greatly appreciated.
bahi3 years ago
Instructables covering the basics are very useful. Good work, thanks.
mic_hviid4 years ago
Nice tut! Thanks!

Anyone knows how to remove some shiny black laquer often found on top of components, probably to obscure their make?

Michael
(removed by author or community request)
actually the intro to this instructable states that it is simply about how to solder components to a pcb assuming it is already made industrially or home-etched. There are many other instructables and sources on the internet for how to do toner transfer and the "uv method" for etching in a home environment.
Well a circuit board is essentially a copper-clad board, usually made of fiberglass. When they make circuit boards they etch away all the copper except for where they want the traces, which connect the "holes" you speak of together.
im certainly no expert, but certain holes on the board are connected so any configuration of parts will not work. for your third question, yes you can do that but i wouldnt, it would make it very difficult. and your 2nd question, your could buy protoboard and use solder to create your own circuits, or buy a very expensive machine to do it, also you could possible use paper and conductive ink but im not sure how far you could possibly go with that. (and if im wrong about anything, somebody please correct me)
D.L.H.4 years ago
Helpful in basic understanding on building such a device glad you made it.
good tutorial lots of pictures & how old do you have to be to buy a soldering iron
If you've got some adults to help out, maybe 10? Check out some of our favorite tools
ok cool my dad is going to buy me one this week
bombmaker25 years ago
Does the 2nd picture at the have an adjustable voltage regulator on it from Radioshack
CuriousInventor.com (author)  bombmaker25 years ago
LM317

You can see the schematics and parts lists here
I thought so
yusaku5 years ago
clinching should only be done if absolutely necessary, increases chance of lifting pads amongst other issues most parts can be tacked in place while holding the part in.
ac-dc6 years ago
There is a noticable difference between 63/47 and 60/40. 63/47 being eutectic is much easier to use because the part doesn't have to be held perfectly still while the solder goes through it's plastic stage while hardening.

Acid core is not too aggressive for circuits, in fact for aged parts it is the preferred solution but it absolutely must be completely cleaned off later. In fact, with today's lead free soldering the industry is using more aggressive fluxes than the old rosin core was, BUT for a hobbyist using new parts I agree rosin core (or no-clean, depending on the project requirements) would be the best choice for typical soldering.

Another *tool* to have is liquid flux. Usually, people apply too much solder to a joint just trying to get enough flux on to make it flow good. There are solders with 3% flux instead of 1 or 2% that will do better or using a separate liquid flux will be the best result. Liquid flux also is very handy when using desoldering braid, allowing excess solder to be removed more quickly and gently by reducing the amount of heat applied, even if the braid had a little flux in it already.

Solder guns do not apply dangerous voltages to a circuit. Not possible. They use an isolating transformer and very low (isolated) voltage. However they are too hot running for most hobbyist electronic work and yet for some jobs, there is no way a 25-30W iron would get the job done so either a heftier iron with stouter tip or a gun would be required.
bobheck ac-dc5 years ago
You guys are really talking about 63/37, not 63/47. Beginners may get confused.
ac-dc bobheck5 years ago
Thank you for that correction, yes since they are percentages, 63% + 47% = 110 (%) would be impossible, I must've been half asleep when I posted that.
CuriousInventor.com (author)  ac-dc6 years ago
As far as I know, the main impetus to switch to 63/37 was for mass manufacturing of SMT devices, not easier hand soldering. Yep, 60/40 has a plastic state, but I personally have not experienced greater freezing time, more disturbed or cold joints, or significantly improved flow of 63/37 over 60/40. One thing that usually isn't mentioned when talking about eutectic alloys, is that a cup of water is eutectic (meaning it's all water or all ice above and below some temperature), but if you put it in the freezer, it doesn't all freeze instantaneously; rather, it freezes from the outside in. The question to answer is, "How much faster does complete freezing occur?" I wonder if anyone's ever done a blind study to see if people could guess which solder they were using. This isn't necessarily for you, ac-dc, but anyone else wading through these comments that wants to learn what eutectic means can visit that link (click expand after alloy, and then click expand again in the "Standard lead-based solder" section).

I could be wrong on this, but doesn't "acid-core" usually refer to copper pipe solder? I'm used to seeing "water-soluble" as the electronics version that is certainly safe to use if it's cleaned thoroughly.

Good stuff about using liquid flux with braid.

On solder guns, I guess the first question to answer is "How much voltage could damage a circuit?" The Weller WES51 brags about having a grounded tip with 2 mv RMS or less voltage, and also zero power switching. What kind of a circuit would be affected by, say, 5mV? 20mV? 1V? Certainly the solder guns don't have 120V at the end, but I'd bet it's in the single digits... correct me if that's off.
If by impetus you mean simply that mass manufacturers are the majority using solder then yes, but it doesn't diminish the benefits of eutectic solder for DIYers hand soldering. Acid-core refers to acid-core, it is not just "copper pipe" you can use on anything you want, including stained glass or due to it's more active nature, exceptionally corroded parts. The problem with it isn't so much the effect on the metal while soldering, as the solder does plate those parts but rather than when it's left on an area it just continues to slowly eat away at it so it must be cleaned off. Personally I find it very handy to use plumber's tinning flux to plate homemade PCBs, since it's readily available, the price is great, and I've never had a problem with it though I do clean off excess flux right after soldering. A soldering gun does not have much voltage, single digit at most IF the tip weren't installed, but it is which pulls down the voltage to practically nothing relative to itself - but you are ignoring the important part - there is no circuit, it's not a voltage relative to anything on the work, only relative to an inaccessible point in the soldering gun itself. With the resistive element being driven by secondary winding of a transformer, it's floating - the only way you would put current through the work is if you soldered a second wire to the inside of the soldering gun then touched that somewhere else on the work.
CuriousInventor.com (author)  ac-dc6 years ago
By impetus, I meant that (afaik) the motivation to switch was to achieve better yields on surface mount components being soldered with paste and reflow processes, not because the manufacturers use more solder. I believe they used 60/40 for a long time for standard through hole components without trouble. I fully admit to speculating here... but I'm still not convinced there is a noticeable difference in hand soldering.
It's not my burden to convince you of something that is fairly common knowledge among those who solder by hand a lot. I stated it because it is a fact, one you simply didn't know and now you resist learning something new.
fswanson ac-dc5 years ago
Why don't you just say I'm right your stupid. Or is is possible there are differing opinions on the best solder to use?
ac-dc fswanson5 years ago
Were you hoping your comment would be constructive? It doesn't seem so. Why would it matter if there are differing opinions on the best to use? There are different opinions on most things, and it doesn't matter. Opinion is irrelevant. What is relevant is accumulation of the details that matter for your project. Some of these might be: 1) Purchase cost 2) Availability - maybe you already have solder or there's a store a block away. 3) Compatibility with flux you might have or need (Or might not need) 4) Whether longevity (leaded) or pseudo-environmental concerns matter more. 5) Whether there is any valid reason to choose a solder that has a long plastic state like 60/40 does when cooling. Otherwise, that it does so can only have a negative consequence. In some solders you might find certain alloys that are eutectic at significantly higher melting point which can be detrimental in use on sensitive components, but that is not significant in 60/40 vs 63/37. 6) Further variables applicable to each project. 7) I didn't ask you to like my answer, but it is factually supported rather than opinion. It is common knowledge and you are welcome to Google search for this. When someone comes along and states something in contradiction to what has already been written, it tends to be for a reason, and it is then time to investigate further - I mean you do so, fswanson, so you have information instead of opinion.
One thing I forgot to mention before about the solder guns:

Even if an isolation transformer is being used, isn't there some risk that the current would go through your parts instead of the resistive heating element? The ColdHeat brand soldering iron doesn't even have a heating element, you have to complete the circuit with your component (The tip is shaped like a fork).
Scurge ac-dc6 years ago
is the liquid flux you mention the same as the paste flux used in copper plumbing? I've not used it on actual parts, but i use it to "prime" de-solder wicks. I should also mention that when i don't have any desolder wick, i just use stranded speaker wire (14 or 18 Ga) twist the strands together loosely and smear a small amount of flux on the wire. it usually works almost as good as the braided wick. incidentally, it also works great to clean up poor solder joints in home plumbing.
CuriousInventor.com (author)  Scurge6 years ago
The liquid flux we sell, or for that matter, any electronics flux is definitely not the same as the paste flux used in copper plumbing. Flux for plumbing is much more aggressive and, even if you attempt to clean it, any small portions that remain will continue to eat away at your board.

The aggressiveness of a flux is independent of it's form, whether paste or liquid. The two main choices for electronics are rosin-based (comes from pine sap, actually) and water-soluble (you can also call this an "acid" type). All water-soluble fluxes need to be cleaned with warm water to prevent corrosion, and are generally used for older / corroded parts. Rosin-based fluxes are generally less aggressive, which means it won't be able to remove as tough of oxides, but it will also be less likely to corrode the board later. There's a large range of rosin-based fluxes varying from "no-clean" types (although "no-clean" can apply to anything, it's more of an ad than a scientific standard) to very aggressive "activated" fluxes.

In the end, if it's water-soluble, you need to clean it, and if it's rosin-based, you need to know how aggressive it is to decide on cleaning.

Neat idea for home-brew wick.
The ideal homebrew flux for DIY hand soldering is rosin based. Essentially rosin dissolved in alcohol, perhaps some water and misc other things in it too. Circuit Specialists sells a 4 oz. bottle for example. Industrial PCB manufacturing has often shifted to a water based flux because of RoHS, and because they can use a pressure hot water spray to remove it. No-Clean is generally put in a solder but not so often desirable as a separate flux as the thing about adding flux is it can easily be removed later, excess isn't a problem, but with no-clean it takes special solvents to remove it and it isn't intended to be removed later being milder than average rosin core (due to being mostly non-hygroscopic) and esthetically neutral because it's fairly clean and colorless.
someone needs to make instructable on understanding how circuit boards work and what does what because i am interested in learning what all this stuff does
I am just getting in to this and i need help with it send me tips please.
feralbeagle6 years ago
As an electrical engineer and someone who has taken soldering classes, I think that this is a very good guide for soldering. Oh, and an excellent choice of tools.

You may also want to check out sites of manufactures like Kester.
Kester Knowedge Base

Here is some info on lead-free hand soldering. (I have difficulty with most lead free solders because it does not wet well)
Lead Free Hand Soldering (the pdf link was broken, this one seems ok)

MIT also has some info:
http://web.mit.edu/6.270/www/contestants/workshops/1-Soldering.pdf

For folks who are starting out or who want to improve their skills, practice more. I think three weeks of class were spent soldering wires together, then having it inspected by the instructor, being rejected and starting over. That's a lot of rejection but eventually we all got it right. The best part of the class was learning what a good solder joint looks and feels like. It has helped me A LOT as an engineer.
Grady6 years ago
I soldered for many years & used to teach soldering, in the 4-seconds - Step. 1st second, iron to connection; 2nd second - solder to connection ; 3rd second - Pull solder back; & 4th second - pull iron away. Do you think this is proper?
4 seconds it too long for soldering circuits. 2 seconds is the maximum it should take to complete a solder joint. Here is a manual that is a little outdated but mostly valid:
http://engr.nmsu.edu/~etti/fall97/electronics/solder.html
CuriousInventor.com (author)  Grady6 years ago
That sounds like a good, quick summary to me. The only catch is that the pre-heating step may take more than a second if the tip is dry, parts are oxidized or the component is large or connected to a ground plane. I might emphasize the 1 second timing less than the results that should happen... 1. Heat the joint until solder will melt onto the joint (sometimes this takes a while, sometimes almost no time, especially if there's an effective solder heat bridge. 2. add enough solder to cover the pad 3. wait for the solder to wick throughout the connection 4. remove iron. The 4 second method is definitely neater :)
Oh, I guess I forgot to tell you that I always had the trainees to clean, then tinn the tips with solder before starting, & to hold the soldering iron as if they were holding a pencil. We had Flux-Solder back then, & I know that the flux-less solder was a lot harder to work with, when it came out. This method of training was so simple that I hardly ever found someone who just couldn't solder, no matter what.
Prometheus6 years ago
Just as a note from me with a lifetime of soldering experience, any electric iron is overrated, use a butane-powered one if possible. Also, the higher heat delivery is great for sensitive components like semiconductors as the process of cold-to-welded is much faster, reducing heat-transfer to the component. Anyone soldering more than just wire joins should have a clip-on heatsink as a backup for tough joints. Lastly, isolated electric irons do not have ANY leakage current, as they rely on heat-transfer to work. Never use an iron that requires an electrical connection be made because as little as 0.3V can destroy certain semiconductors. The ideal is using a gas-powered iron, and drawing the solder to the pin rather than just melting it around the pin. Solder always runs for the heat, as if a desire to remain molten. You may need to tin your work to get proper heat transfer, but solder is generally fed opposite the iron, not into it. And I think you mean 53/47, not 63/47....110% solder is hard to come by lol... Just a few tips for the hobbyist
CuriousInventor.com (author)  Prometheus6 years ago
Could you elaborate on the cold-to-welded bit? I've never heard that all electric irons are overrated... it would seem that a good temperature controlled electric would be safer, as its heat delivery is throttled to maintain a given temperature. With a butane iron, is there any feedback control over the tip temperature?
Electric irons, while some are good, do not fare well when it comes to a quick and clean joint, as they are often not hot enough to make that joint without heating the component as well. You want to come in hot and fast (but not too fast, or you will make a cold-solder joint). With butane irons, you control the tip temperature by regulating fuel flow. The only disadvantage to butane irons is the exhaust vents in confined spaces.
CuriousInventor.com (author)  Prometheus6 years ago
This gets into a larger question I've been pondering for a while now... "How much temperature and heat do you want?" First, I think that an electric iron with sufficient wattage and temperature control should be just as good as a butane powered iron, and possibly better since the electric iron can regulate heat delivery to maintain a particular temperature. Unless I'm mistaken (and please point out if I am), a butane iron simply delivers a constant heat, so the tip temperature can vary significantly depending on how much heat is lost to the surrounding air and component / board. This comparison only applies to electric irons / stations with active temperature control; butanes may certainly be better in general than unregulated electric irons.

But back to the question... what would be an ideal heat delivery and / or temperature? So we want to heat the joint without heating the component or damaging the board...

As shown in this video, using a small 25 Watt iron on a large wire results in high temperatures far away from the end of the wire (where you don't want them), since most of the heat is "sucked" away before it actually goes into heating the end.



One thought is to use an extremely hot iron all the time, so you can get the connection above the melting point of solder before the heat has a chance to spread.

But this goes against the advice from a lot of reputable sources (IPC soldering instructors) I've heard stating that lower temperatures are almost always better. In fact, most high end soldering stations can be locked to prevent operators from using too high of a temperature.

I suppose every different situation would have it's own ideal heat / temperature...

One more thought: in industry, entire boards are elevated above the solder melting point for more than a minute or two as they travel through reflow ovens.

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