Soldering Review Request

I am wanting to improve my soldering capabilities and Chris just suggested to me that I should post an example of my soldering and ask for feedback.

This is the one of my assembled annoying buzzers, and I think it is a good example of my current soldering ability. Let me know what you think and give me some feedback.

You have a good start. @farmhacksca Do you have any flux available? Some of the joints look rough/jagged, adding the flux just before soldering helps the Joint’s flow just a little bit better.

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Hey. I’ve actually just started to use flux. I plan to more often since it does seem to help.

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Something I like to reference as a visual guide is actually this from NASA: (Links not allowed) Google “NASA Workmanship Standards Soldering” for a neat pictorial PDF.

Also this: NASA-STD-8739.3.pdf

with this training manual to go along with the second link:
“NASA Student Handbook for Hand Soldering.pdf”

And this is neat for the yesteryear vibes alone : NASA-Soldering-Basics-1.pdf

Board looks fine, but needs the flux to be washed off, and the small cap has too much solder on the leads, looks dangerously close to bridging.

Overall, about on-par with my own skills :rofl:

If you don’t mind, I’d like to know more about your soldering equipment, supplies, and technique.

For example, you mention that you’re using flux: What kind and how are you applying it?

What kind of solder are you using? Composition, diameter, and core content (if any?) I ask because, for example, I’m a huge fan of 63/37 eutectic tin-lead solder for home assembly (where I don’t have to adhere to RoHS rules) and I like to use pretty narrow-gauge solder so I have good control of how much I feed in. It does look like you’ve got a bit more solder than you need on most of your joints, and you’ve also got little spires coming off, which suggests it is not wetting together and being shaped by surface tension.

What kind of iron are you using? Is it temperature controlled with a base station and thermostat, or are you using a fixed temperature iron with no controls? If it is temperature controlled, how hot are you running it? And to be clear, no judgement here: Like so many things (cameras, guns, friends…) the best soldering iron is the one you have with you, but there is a huge range of equipment available, and even at the low end a small investment can get you big returns on usability.

How are you cleaning and tinning the tip of your iron? I really like the shaved-metal ribbon cleaners over wet sponges, to not sap the temperature as much, and dippable tinning paste. And what size and shape of tip are you using? Is it clean and well tinned (shiny all around) or are there any corroded spots?

How do you clean up excess solder? I like to have solder wick in several different widths, but sometimes I also like to use a solder-sucker…

How good are your eyes, and are you using any magnification? My eyesight is terrible, so I use a head mounted magnifier for almost everything, unless it’s really small, and then I use a binocular microscope (which you can find surprisingly cheaply these days, at least compared to 15 years ago…) And if you are one of the lucky ones that doesn’t need any magnification, are you using safety glasses to keep little bits of ejecta out of your eyes?

And I know this is a lot already, but could you describe your sequence for putting down SMT components in particular, both two-lead passives and the SOICs?

And as mentioned above, some basic cleaning stuff is always good, both for shining up pads BEFORE you solder, and cleaning the flux off AFTER. Q-tips and 99% rubbing alcohol (aka isopropanol, aka isopropyl alcohol) will get you far.

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This is basically what I was going to say, but better!

Generally speaking, the solder joints look like they have too much solder OR were not heated well enough before solder was applied.

For most of my soldering I use a tip temperature of 280°C (300°C for thick boards or for joints that are connected to large copper “islands”), and a soldering iron capable of heating the entire joint to the solder’s melting point.

I use very thin, high-quality rosin-core 60/40 solder. I still have large rolls from Radio Shack, but if I run out I will probably use Kester solder. There’s no good reason to use poor-quality solder. You might save a couple of dollars, but you’ll curse the solder after fighting to get good solder joints!

When I use flux, I use the no-clean stuff - even if I plan to clean it up afterwards. Activated fluxes (RA, RMA) need to be cleaned extremely well to avoid corrosion that can lead to development of low-resistance paths between pads.

Right before making a solder connection I clean the tip with brass gauze and tin it with a tiny bit of solder or solder paste in a can. Then I touch the tip to the joint, making sure to contact both the pad and the component lead. After a second or two I apply a small amount of solder and allow it to fully wet the joint. Then I apply just enough solder to form a concave connection that fully wets the pad and component lead. I try not to use an excessive amount of solder, but if I accidentally apply too much I do not attempt to remove the excess unless it poses a shorting risk. I average less than 5 - 10 seconds per joint, though sometimes more for large copper areas that require a lot of heat. The soldering iron has to have enough power to heat the whole joint enough to allow solder to flow readily.

I usually do not clean and re-tin the tip before every solder joint if I am soldering many joints in rapid succession, but I will clean and re-tin every 5 joints or so, or earlier if I see junk accumulating at the tip.

TL;DR - Clean surfaces, non-activated flux, good rosin-core solder, and a soldering iron wirh a clean, tinned tip and capable of at least 250°C with enough power to heat the whole joint adequately. And lots of practice to get good-looking joints in no more than 10 seconds (except for the occasional joint with large amounts of copper, because these act as heat sinks). And look at the workmanship standards for solder joints!

Thought I would just reply answering a few of the questions.

I am using tin/lead 23 gauge solder solder. I can not see what is the percentage make up of it, and I forget where I even bought it. Below is a photo of it.

Soldering Iron
It is a temperature controlled iron. I am usually using around 600 °F (315 °C), and sometimes a bit higher. It does not have a base station and is controlled just at the grip. Below is a photo of that.

Flux and solder cleaning
The flux describes itself as ‘High Quality’ and ‘Advanced Soldering Flux’, but really on the box it does not seem to say much about it. I think it may have came with my soldering iron. A photo of the lid and the paste/flux is below:

For cleaning the solder tip I have a little metal sponge that I use. It is shown below:

Cleaning up Solder
Currently I do not have much of a method for cleaning up excess solder, and have no special tools for it. Sometimes I try and use the soldering iron by trying to drag the solder away from where I don’t want it, but that really does not work well.

Magnification and Eyes
I have not soldered anything so small that I need magnification. I wear regular glasses, but do not use safety glasses or similar.

SMT Soldering
For the SOICs I usually put a dab of solder on one or two pads before placing the device and then I place it and solder those pins first. After those pins are soldered the chip is usually fixed enough that I just go ahead and solder the rest.

For the two pin passives it is very similar, but I only put a dab of solder on one of the two pads.

Thank you all who have replied with great advice, but in particular @PKing and @Jverive because I largely wrote this reply based from their replies.

Thanks for the more details!

Your solder is the 63/37 composition I like:

What’s nice about that is that it has a single-point melting temperature that is the lowest of any tin-lead alloy combination.

I’m not familiar with that iron, but I looked it up on Amazon, and it looks pretty interesting. They claim 110W, which should do a good job on even very large solder joints, because it can dump a LOT of heat into it.

That flux paste does say that it’s “high activity,” which means you’ll want to make sure to clean up residue from it when you’re done to preserve the long-term health of the solder joints. I have also had mixed luck with bulk paste just from an application point of view. Two other application methods you might try are a needle-tip bottle with liquid flux:

or a flux pen:

I’ve not used them, but some people I know like flux paste in a syringe dispenser:

(Note: These are just photos from Amazon to illustrate the general category, not specific examples from my bench.)

I do encourage you to try out solder braid for removal of excess solder. It’s surprisingly helpful once you get used to using it. Your first few times you probably will end up soldering it to your board, but you’ll figure it out!

Your SMT technique sounds pretty good! And while you note that you haven’t needed magnification, if you have some available, I encourage you to try it out, because then you can see how the solder is flowing around the joint, and shaping up as you have the iron applied and as you remove it… Here’s a random YouTube video that illustrates what I’m talking about:

Like you, and unlike some of the attachments in this video, I tend to pre-tin one pad, but here they are just using solder carried on the tip of the iron for the initial tack-down. This also illustrates well just how little solder you need for a good joint.

And, of course, “practice, practice, practice…” There are some great cheap practice kits that are just arrays of SMT components on a dummy board for working toward “the perfect solder joint,” though if I’m going to be soldering anyway, I generally prefer to assemble something functional!

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