Introduction: Make Beautiful Solder Joints

The quality and design of project boards has become so good in recent years, that I almost feel bad putting them together. In this guide, I'm going to show you a simple soldering technique that can make the back of your boards look as nice as the front. You'll learn how to make perfectly smooth, consistent solder joints that look impossibly tidy.

In full disclosure, I learned this technique from Saar Drimmer, who runs Boldport and sells stunning kits (some shown above, with permission) through his club. I don't work for them or make any money from them, I'm just a fan.

But as a fan, I had this dilemma of loving his board designs so much that I didn't want to destroy them with my haphazard soldering. The boards in his photos looked immaculate, like the soldering had been done by a robot.

It turns out he was just using a technique I hadn't seen before (also described in his video here). I suspect the technique predates Boldport, but I refer to it as Boldport Style. If there's already a name for this I should know of, please correct me.

Step 1: Create a Standard Through-Hole Solder Joint

Picture of Create a Standard Through-Hole Solder Joint

First, you just need to make a standard, through-hole soldering connection. Nothing fancy. No special solder or soldering iron.

For what it's worth, though, here's what I'm using (linked out to Amazon):

Hakko FX-901 Portable Soldering Iron
Love this thing. Heats quick, gets hot, solder anywhere. I use rechargables.

Hakko CHP-170 Flush Cutters
THE critical tool for making this technique work, though any flush-style snips will work.

Lead Free Rosin-Core Solder
Because it turns out lead is toxic, so why not?

Brass Wire Sponge
Cleans without water. Keeps your tip hot. Looks like C-3PO's... er, ashtray.

Safety Glasses
All those clipped leads have to go somewhere. Better it not be your eyeball.

If you need any guidance learning how to solder, Adafruit has a great guide. I also love the EMSL guide on how NOT to solder.

Step 2: Flush Cut the Joint

Picture of Flush Cut the Joint

Next (with safety goggles on your face!), trim the lead or wire you just soldered down as flat against the board as you can go. Basic wire cutters won't get you all the way flat, that's why the flush cutters are key.

If you've received any instruction on soldering, or read any books on the subject, you've likely been warned not to aggressively cut the solder joint down all the way. For all practical reasons, they're right. If you're soldering up something that has a critical task and people depend on it working, don't monkey around with fancy soldering tricks. You could damage the board, weaken the joint, and generally ruin someone's day.

That said, if you're soldering up a blinky robot badge (like me) and don't want the backside poking your shirt. Or maybe you've got some artsy, portable project that people are going to fondle at Maker Faire -- then by all means, live dangerously and flush cut that sucker in the name of beauty.

Step 3: Reheat Joint With Dab of Solder

Picture of Reheat Joint With Dab of Solder

Now, the trimmed joint may be flat, but it's not pretty until you briefly reheat it and introduce just a touch of solder.

Poke your iron back into the joint just long enough to see the solder liquify, then add just the smallest amount of new solder back into it and pull your iron away. This will take some practice to not go overboard with the solder or leave your iron in too long.

Ideally, what your left with is a smooth, shiny dome of solder that reminds me of a mini upholstery tack. My guess is that it has something to do with the surface tension created by adding new solder and the lack of any central element for it to gather around.

When you do this across every solder point on a board, the cumulative effect looks really sharp. And because every joint is built up from the same flat starting point, I find it much easier to get a consistent look from point to point.

That said, pulling off this trick essentially means soldering every connection twice. For a few dozen connections, it's cute. For a few hundred, it's a chore.

Step 4: Remove Flux

Picture of Remove Flux

And since we're being all type-A about making the board pretty, take a moment to soak a rag in some rubbing alcohol and scrub away at the little pools of flux left behind on each joint. With the solder points all smooth now, it's really easy to scrub away at the board without hurting your hands or getting the rag caught on the leads.

For what it's worth, I also have a can of stuff called Flux Off, but I don't recommend it. It's nasty stuff with all kinds of warnings on the side. Especially with the smoothed out solder connections, rubbing alcohol and elbow grease tends to get the job done just as well in most cases.

If you liked this tip, be sure to give me a vote!

Comments

StephenA21 (author)2017-10-29

I've done this before, and like the results. But I wanted everyone to know about a possible complication, which sort of reinforces the warning given by the author not to do this on important circuits.

Shortening the leads like this allows the component to fall out partially if you hit both leads at the same time (like with 5mm white indicator LEDs) or if you switch too quickly from one lead to the other. And you may not be able to tell if one of the leads has a poor connection, because the smoothness of the finish hides whether the lead is in or out. So, I try to keep track of the component position and angle especially, as well as reinspect after finishing. And I also tend to do all left leads at once, and then all right leads in a separate operation, thereby ensuring that both leads aren't in the melted state at the same time. This way of soldering also reduces the chance of overheating a component, since you're allowing it to cool down before heating up the other side. Hope this helps.

el_badger (author)2017-09-29

This is great!! I have been soldering since 1990 and my joints still look amateur-ish. I am self-taught and know the basics but now I will have technique.

beul (author)2017-09-21

Thank you for shared, i like it

MakersBox (author)2017-09-16

Crazy comment thread. Where do I put in a request for an "Soldering to IPC Standards" Instructable?

gm280 (author)2017-09-10

It is good you are re-flowing the sold after cutting the wire. That way there is no dissimilar metals exposed to start corrosion. A different idea, and the way they teach you in the NASA certified soldering schools, is to cut off a small portion of the component lead, lay it down flat next to the feed-though component lead and use your flush cutters to cut the lead to the diameter of the lead. Then you solder the lead and everything is covered and finished at once. I used to be a NASA certified micro-miniature solderer for decades. Retired now.

SteveJ25 (author)gm2802017-09-16

thats military spec so its expected. these are just consumer projects so the standard doesn't have to be that high

Elohira (author)gm2802017-09-12

Could you please clarify this? I was following you right up until the "cut the lead to the diameter of the lead". It sounds like something I would like to understand. Have you ever considered doing an instructable that would give additional tips on soldering or micro-soldering? I think that would be a very useful instructable.

gm280 (author)Elohira2017-09-12

Elohira, What I mean is you cut a small portion of the component lead off. Then you lay it flat next to the though lead of the same component. The stay a flush cutter and use the cut off lead to cut the component lead to the same height. That would make the component lead the exact same length as the diameter of the lead. Then you remove the cut off lead and solder the connection.

Elohira (author)gm2802017-09-14

Thank youl. That makes it entirely clear

stevefah (author)Elohira2017-09-12

I think what is meant is to cut the height of the protruding lead to the width of the wire. So if the wire is 1 mm in diameter, let 1 mm protrude before reflowing the solder.

JohnC430 (author)stevefah2017-09-13

Thanks. what you say makes sense.

JohnC430 (author)gm2802017-09-13

I did not understand what you wrote. I am a NASA engineer and have do some soldering now and again but have not taken any soldering classes at NASA. I re-read what you wrote and cannot understand it. please if you don't mind, say it differently so I can understand. Sorry to bother you. Thanks.

jtechian (author)gm2802017-09-12

I also had the NASA soldering classes, although I managed only class 2 certified. I was a missile tech some 30 + years ago.

This type of soldering was always called blob solder and is not a way to have a good solid connection. The clenched lead is always going to be the strongest.

Semper Fi...

pgs070947 (author)jtechian2017-09-13

Familiar with clenching nails, i.e. turning over, usually on the backside, but not heard of it for wiring.

I'm probably already using it, but hadn't named it. A classic use is when attaching flying leads to a board. A flying lead, just through the hole with no support is soon going to come adrift and start to rotate and lead to some funny results.

With flying leads, I push some excess stripped lead through the hole, trim it to leave a few millimetres sticking out. Turn it over 90-degrees and solder.

Result is a much stronger, non-rotating flying lead.

Just as an add-on, a good flux is key. Never rely on the cored flux alone, but now exclusively use a syringe of Chip Quik. Gooey, but good.

Donald Bell (author)gm2802017-09-12

I love this idea. I'm excited to give it a try.

Veda88 (author)gm2802017-09-12

This is actually better than what the instructable teaches. Because when cutting flush to the board after soldering, he is putting heavy tension on the copper island on the board, which might get loose because of that. Cutting the wire short before soldering will not give you the risk of loose copper tracks.

PaulA23 (author)Veda882017-09-12

...also called "lifting a pad", and is VERY frustrating when it happens... :-)

VincentJ2 (author)gm2802017-09-12

Just FYI, this is mostly for appearances. If your assembly Is going in something critical like medical patient qualified devices, nuclear power plants or SpaceX Rockets, your friendly IPC quality inspector is going to have a conniption fit. ;)

It is in fact beautiful though.

geotek (author)gm2802017-09-12

In Mill-Spec soldering the joint must not have any exposed copper, so the hand soldering technique is much like shown here. We had a flow solder machine that flowed a layer of wax on the solder side of the board to hold the components in place. Then a lead saw cut all the leads to length. The board was then brought over the solder wave and soldered. It produced perfect solder joints, but like most flow solder machines, there was a lot on maintainance.

mcmasterp (author)gm2802017-09-12

That's a neat trick and a neat job

weish (author)gm2802017-09-11

that's really cool. I'll remember that trick we the sare component leg as an offset for the flush cutters next time I'm soldering anything through hole

SteveJ25 (author)2017-09-16

you are suppose to use 91% alcohol to remove flux

algobe (author)2017-09-14

Good to know Thank you for your tips

JacobZ1 (author)2017-09-12

The problem with this is that it doesn't meet IPC soldering standards. the lead should be visible. For hobby circuits this wouldn't be a big deal, just know this wouldn't fly in a professional environment.

Donald Bell (author)JacobZ12017-09-12

I absolutely agree, and I acknowledge in step 2 that this is an aesthetic hack that could lead to a less reliable circuit and shouldn't be employed in situations where reliability is critical. But if you're soldering up a sweet-looking electronics kit, using this technique can make your board look and feel nicer.

gthompson20 (author)Donald Bell2017-09-13

It creates a solder joint so unreliable it should not be used anywhere, but if you are more interested in a cct looking good than actually working, then it is probably ok. My problem with this type of instructable, is people who have no idea of what they are doing might think it is a good idea.

VincentJ2 (author)JacobZ12017-09-12

True. There should be lead protrusion as well as a concave fillet. Although if there was evidence of the lead in the hole on on the destination side but no lead protrusion on the source side that would make this Acceptable for Class 1 and a Process Indicator for Class 2 and 3. So it isn't a IPC defect, but you're going to spend a lot of time arguing that with your quality inspectors.

JacobZ1 (author)VincentJ22017-09-12

Exactly. In my opinion though, Class I shouldn't even exist.

VincentJ2 (author)JacobZ12017-09-12

Oddly enough Class 1 is still a step up from consumer grade electronics. I've seen some stuff that was substandard even by Class 1 standards. And we pay good money for it. The thing that bothers me the most is that it takes the same amount of time to do a good job than to do a crappy one.

JacobZ1 (author)VincentJ22017-09-13

Haha, tell me about it! It's frustrating that a lot of manufacturers don't care what the product looks like as long as it works and they can make some money. Such a shame.

veyo (author)2017-09-13

this looks nice but doesn't comply with IPC norm

Donald Bell (author)veyo2017-09-13

Exactly. I'm not the guy who should be writing how to make technically perfect solder joints. But it's a neat technique for projects where beauty trumps reliability.

gthompson20 (author)Donald Bell2017-09-13

You mean where beauty trumps reliability and proper workmanship.

gthompson20 (author)2017-09-13

Having worked in the aerospace industry this goes against everything we were taught about a good quality solder joint. If you want a good looking solder joint, learn how to solder properly.

noel.kuck (author)2017-09-09

One thing that I was taught back in the 70s, and still practice today, is to apply the heat opposite the solder as the heat will then draw the solder into the joint.

JayGee59 (author)noel.kuck2017-09-13

Lots of good advice and here is more!

IF your component leads do not look shiny take a small piece of fine plastic pad like Scotch Brite and "polish" the lead.

IF the above doesn't get the crud off try pre-tinning the components leads and you will have much better success with your soldering.

cybercapri (author)2017-09-12

Awesome technique I wish I had learned to solder as a kid; seems the phrase teaching this old dog a new trick applies... I've been watching folks solder, on YouTube Videos for over 10 years now, tried it while watching many times, and I still can not seem to grasp the basic concept... I can solder Copper Water Pipe as good as any Pro, but tiny electronics seem to be my Kryptonite... Cheers...

JohnC430 (author)cybercapri2017-09-13

first anchor the part you are soldering, by bending the lead a little so it does not move, after you push it thru the hole. then use a hot enough iron. then apply solder and let it flow into the joint. remove the solder wire and hold the iron in place for a couple of seconds.

lift the iron and wait until the solder cools. There, you have a nice solder joint.

KeithAZ (author)2017-09-13

This is a setup for disaster, sorry. Sure it is pretty and nice to the touch. But that's not the point for functionality and longetivity of a proper solder joint. Firstly the "mountain of solder" shouldn't look like that, it should be almost concave or even sloping from the outside of the pad to the top, to visible show wetting took place. A mountain is a sure sign of a cold joint. Clipping the lead then shocks the joint and could fracture your weld, but as you should know a cold joint already has fractures and can fail. Then adding a dab of solder over that hides the mistake already present and with a properly heated joint they would not bubble like that, another sure sign of child joint. This is also hiding the lead you are wanting to make sure it's in that connection (good luck finding a problem you can't see). Last on this rant stop "touching" your electronic boards you're mentioning this practice to touch? Repeatedly? I can't get over the years of ESD training and standards i have learned while in the electronic manufacturing industry.

GaryD23 (author)2017-09-12

acetone (pure, from a hardware store, versus the perfumed stuff sold in cosmetics aisles) will remove some flux compounds far faster than alcohol. No rubbing needed.

pgs070947 (author)GaryD232017-09-13

Acetone. A bit risky in my opinion. Too aggressive, too flammable, too much unpleasant vapour.

Might be useful in a few circumstances, but not for routine use.

The other problem is availability. UK hardware stores won't keep it, a specialist like a finishing supplier might do it, but as now you almost need a licence to buy solvent based glues, it might be better to stick to IPA.

EldarM1 (author)2017-09-13

Hey, good tuto!

But before the step 3 I still recommend to sold all the leads. So your component will not move by reheating anymore.

Lubomir73 (author)2017-09-12

Don, I can see how this would make a beautiful looking board. I have no certifications in soldering, just been doing it since mid 1960's. I prefer to use solder with a small amount of silver. Joints look shinier than the standard solder. One caution to those trying this technique on one sided boards, after flush cutting and then re-soldering, the component lead may pull away. Yes, you do have the board upside down and gravity and lead tension are pulling it down. This may result in a gap between the solder and the lead. Not so critical with plated through holes but could result in a disconnected lead on a one sided board. Thank-you Don for giving us a view of beauty in soldering.

rch (author)2017-09-12

My old PACE soldering instructor would be having a fit over this. While it is neat looking, in a way, I cant imagine it being as structurally strong as a proper solder joint. Concave fillets are part of the proof that you have a joint that was made at the proper temperature, from what my ancient brain remembers.

altamuu. (author)2017-09-12

you could use a solder that has no plastic state like eutectic solder.

burzurk (author)2017-09-12

oh ..nice Instructable too!

burzurk (author)2017-09-12

Love that NASA wiring manual!!! Wish they'd update it tho.

Patrick_MG (author)2017-09-12

Very cool!!! Welding with professional finish

chezlog (author)2017-09-12

Short, sweet, great!

lbrewer42 (author)2017-09-12

Its good to see price in a job well done is not a totally lost art. Good job!

About This Instructable

22,295views

312favorites

License:

Bio: I run the Maker Project Lab blog, and a weekly video series called Maker Update. Email me at donald@makerprojectlab.com
More by Donald Bell:Too $hort CatMake Beautiful Solder JointsRaspberry Pi Home Network Music System
Add instructable to: