Soldering q's

hi everyone,

scoured the current forum for any soldering advice or iron recommendations, but came up empty. also figured with the fire sale on grid kits, this might be a gold thread to start.

long story short: last night, I tried building a Mikrophonie with a mom and pop shop iron. decently thin tip, but the thing’s kinda self destructing and I made a mess of my beginner project. ¯_(ツ)_/¯ no major losses, but before I take on another, I need some guidance. of course, I could always just stop and buy fully assembled units my whole life, but there’s no fun in that is there?

THONK recommends watching a video that’s now behind a paywall and reading the Arduino soldering guide, which tells me a lot about good connections but little on how to achieve them.

anybody have recommendations for irons and practices that would be good for building our favorite bleep bloop machines?

thanks for any input and guidance!

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there are a few threads on this that are archived on the old monome forum; hopefully still relevant:

http://archive.monome.org/community/discussion/18281/what-soldering-iron-did-you-buy-for-your-grid-kit/p1

http://archive.monome.org/community/discussion/4276/finding-really-hard-to-solder-to-logic-board/p1

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There’s a ton of videos on YouTube for beginner soldering. I use a cheap iron with a thin tip and it works fine for through hole but doing guitars and stuff is a nightmare as it struggles with thicker solder. How exactly did you ruin the microphonie?

Key points, heat the plate not the component and not the solder. Google cols joints and look at pics to see what a good joint looks like. Smt is a bit different, you’ll need tweezers and maybe a magnifying glass depending on your eyes and the sizes.

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I used this iron for my grid kit:

Weller WM120 12w/120v Pencil Thin Soldering Iron by Weller
Link: https://amzn.com/B0000WT586

And this solder:

KESTER SOLDER 24-6040-0027 60/40 Stand, 0.031" Diameter, “44”, 1.5" Kester Solder
Link: https://amzn.com/B00068IJPO

I tried first with a thicker iron, that i had from another small project and it was impossibly hard to get anything soldered. However with this stuff above, It was a breeze putting the whole thing together.

This was also the first time I tried any electronic soldering with a real circuit board!
You’ll definitely need some nimble tweezers for holding those small parts too.

Have fun – its a blast putting together once you get it rolling.

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besides soldering in a component backwards, I kinda torched the board a little trying to desolder it. “heat the plate, not the component” was advice I had heard but didn’t fully understand.

Oh no. I’d just bought a Mikrophonie too (and soldered a diode in backwards… but luckily fixed it). I did buy a decent iron though after some bad experiences a few years back with a cheap one.

The original video got made pay only and that can’t be undone apparently, it’s been re-uploaded by the owner:

Read the Adafruit guide, this thread from MuffWiggler is great too.

I caved and bought a Hakko 888D, much better than the cheap wand I had before. Solder, definitely go with leaded, your choice is between 60/40 or 63/37 (eutectic), I went with Kester 245 (no clean) and 331 (organic core), I bought 0.02" first, but found that to be too fiddly for through hole, so I bought some 0.031" and that was much better.

Firstly are you sure it’s broken, or does it just look messy? Which diode was it? The big 1N4001? Or the little 1N4148 one? I bought some solder braid (and a new diode - or rather a 100 new diodes) to fix my mistake, it was a total pain to get the hole cleaned out. Paradoxically I had to add extra solder into the hole to get it to wick into the braid.

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mikrofonie was my first diy project a year ago and funnily enough i did the same mistake (diode other way around.)

It was not until fairly recently (10 modules in and a synth) that I tried a surface mount soldering project which is the type of soldering needed for the monome. here is one possibility: https://www.thonk.co.uk/shop/music-thing-modular-simple-eq-full-kit/

I would recommend trying out first a project as it needs you to be fairly comfortable with the solder…

I am receiving mine as well, so will share more on the overall experience.

It’s quite possible the board is still fine. You may have burnt the PCB causing the surface to blacken and bubble, but chances are it’s still ok. Try not to spend more than 3 seconds on a joint. If the solder isn’t flowing within that time you probably don’t have a good enough contact to transfer the heat. I tend to have a small blob of solder on the iron, press the blob against the plate then feed solder into the joint, not onto the iron. I’m not an expert though. I’ve built a Mikrophonie it’s a great module, worth persevering with!

“heat the plate, not the component” was advice I had heard but didn’t fully understand.

Well, you can sorta do both. You don’t want to apply heat to components for minutes on end because they don’t like it - especially ICs - but basically, my approach is:

  • put the iron so it touches the pad you’re soldering to, and, ideally, the leg of the component
  • hold it there a second or two
  • now feed the solder in gently. it should melt and flux around the leg and to the pad.

never hold the solder by a component and then push the iron onto it: you’ll just make a mess that way. Also: tinning the tip of the iron before you begin is important.

It’s highly unlikely you’ve made a total mess of the board, and it’s also highly unlikely it’s “self-destructing”. If it looks like connections are unstable - that’s just bad soldering and cold joints. Take some braid or a solder-sucker - both pretty essential to have kicking around - and tidy up and redo the joint. Remember: this is just a skill people learn, it’s not immediately obvious, and you can totally do it!

If I could make one overall recommendation, it would be: don’t use lead-free solder. Yeah, yeah, something something health and safety, but it’s all rubbish, and requires a hotter iron than 60/40 lead tin. Lead/tin flows brilliantly, just works, and for DIY volumes is entirely fine. Just wash your hands after using it.

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Also, I will second this adafruit guide that Sam posted - that picture at the top is excellent. frequently, a cold joint can just be gently reflowed by applying a hot iron. just because there’s solder around a pin and a pad doesn’t mean it’s correctly done.

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Paradoxically I had to add extra solder into the hole to get it to wick into the braid.

The solder we use today tends to also have flux in it - adding extra solder will also release extra flux, which will help the solder from the board flow into the braid. Similarly, it’s why when reflowing a cold joint, sometimes, a dot extra solder will be enough to make it flash neatly, and then you can always mop up excess.

First in three part tutorial on how to solder like a pro, really helpful, not only for beginners

+1 on lead solder.

I always thought the main reason for using lead-free was to stop it ending up in landfill (and we’re not talking about the tiny quantities used in DIY), rather than the immediate health dangers.

yep, it’s a requirement to use lead-free in anything that might be manufactured. I think that’s reasonable - especially given they’ll be wave-soldering on proper SMT beds.

but for doing it by hand, god, the lead-stuff flows so much better.

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Second the recommendation for the EEV blog videos. I watched them before committing to my first project. Also, see if there’s a Maker group near you. I did a day with the Dublin maker.ie guys which was very helpful. A little impatience that day taught me much about recovering from mistakes!!

It was the 1N4148. I kinda panicked a little and ended up destroying the diode.

Oh man, I didn’t even realize how cheap these replacement diodes are. Huh. Where do folks get their parts usually?

:sweat_smile: iiiiiiiii’m not so sure, it looks rough. also, funny: I feel so vulnerable sharing this!

after watching some of the excellent videos posted here, I think that my issue lies in an iron that just doesn’t get hot enough. I’ve had to hold it down for almost 10 seconds before getting anything flowing. using 60/40 lead solder with flux.

I might go this route. Seems like it’ll be good for my entry/hobby level, though the Hakko 888D is now on my Amazon Wish List.

Thanks for all the help, everyone. This is great conversation!

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that board looks totally fine.

remember you can always simply reheat solder joints to smooth them out. often when learning soldering people use too much solder, but this job looks pretty good! hard to see with the reflections.

parts come from digikey and mouser!

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OK - so it looks a bit rough but basically you have done nothing harmful whatsoever. Also, you can clean up boards pretty easily - that brown stuff is just flux and there are lots of posts online about cleaning it.

Otherwise, you’ve got a mixture of solder joints - some are fine, some are a tad on the blobby side and could be cleaned up with a sucker or braid, and a few could be clipped closer to the board - I really recommend right-angle clippers. But don’t beat yourself up about it - lots of ‘clean’ DIY boards have been cleaned once soldering is complete.

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it looks overall fine and functional, but generally too much solder (common beginning mistake.) ideally there should be just enough to cover the hole, the surface should be sort of concave and shiny/smooth:

you know you’re getting a good joint when you heat the pad+leg, apply solder to pad or leg, and the solder kind of gets sucked down into the hole.

looks to me like you could potentially have a couple cold joints (like in the lower right.) easy to fix; just re-heat. use braid or just a dry iron to wick off some of the excess blobs.

don’t worry about the burned flux.

my personal thoughts on equipment: its worth investing $100 or so in a proper soldering station if you are going to be spending significant time/effort/expense building things. (or if you just hate using sub-par tools.) IMHO the time-tested weller WES51 / WESD51 (digital) are the best bang for buck, comparing favorably with the high-end Metcal stations.

oh: i also recommend cleaning and tinning the tip of the iron after use to prevent oxidation and prolong its life. if you are having a really hard time getting things sufficiently hot, and the tip is looking sort of eaten-at, it could be time to replace it.

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I found it interesting that Peter Blasser was a bit shocked and horrified at the prevalence of leaded solder being used by participants in his recent Noisebridge workshop. Pb is a big advocate of the use of lead-free solder. Just an interesting tidbit.

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