State of the art SMD/DIY best practices

Larrea · 2017-03-03T01:00:26.334Z

Okay, protestations against not having time notwithstanding, let’s say I want to start building a module or two.

I have a good soldering iron and all the basic, if old-fashioned tools; solder sucker, clippers, vice stand, etc.

With some brief practice, my soldering skills will be good again.

SMD stuff baffles me.

The questions:

Do I need an oven or can I confidently tackle these with an iron?

What else do I need to tackle SMD stuff and Eurorack modules in general and not hate my life?

Even dumber question:

When sellers specify “PCB” does that include all the parts (and I mean ALL the parts) or just the actual board? I’m almost embarrassed that I don’t know this, but I don’t know this.

The panel aspect is clear(er) to me.

If I have to source parts from all over creation, this is a total non-starter for me. But if someone sells me every single thing I need in one bag, I’m in.

Thoughts? Guidance for a Eurorack DIY n00b?

Jonny · 2017-03-03T01:21:33.540Z

Great topic idea- I’m new to SMD as well. My experience so far has been with through-hole modules, like the Music Thing Turing Machine and Radio Music. This built up my confidence quite a bit. If you haven’t done projects like that first, I would start there, maybe with some of the Thonk projects or a Music Thing Mikrophonie.

For my first SMD project, I’ve been assembling the parts to put together Microbraids, the Mutable Braids clone in half the HP. I’m also interested in putting together an Ornament and Crime module too. Both of these modules involve sourcing parts, but it’s not that terrible as the BOMs have Mouser part numbers. There’s also some flashing of chips too since these are digital modules.

Regarding PCB, that’s usually just the printed circuit board. Thonk indicates ‘full kit’ when all the parts are included.

Anyways, I wasn’t sure if I wanted to pursue an SMD project. The most daunting thing for me was the ICs, but there are a lot of youtube videos showing people doing it with flux and a small glob of solder on their iron. Some examples show using a solder braid/wick to clean the excess solder. I’ve picked up a chisel tip to make this easier (swiping across the pins).

I don’t think you need an oven for most projects, but I’m new to SMD. Perhaps somebody can enlighten us?

Larrea · 2017-03-03T01:34:17.835Z

Jonny, thank you. Good idea doing a warm-up build!

I found a used Radio Music a month ago or so, so that’s covered.

Thanks for clarifying about the PCB too. The acronym of course suggests just the board, but I didn’t want to assume anything.

Let’s see what others suggest.

trickyflemming · 2017-03-03T01:38:47.976Z

I do all of my SMD builds by hand. I don’t want an oven (frequently referred to as “firestarters”) in my apartment/home office.

PCB means no parts. Assuming that you are tackling NLC builds, nearly everything (including pots, jacks, and knobs) can be found cheaply at Tayda: https://www.taydaelectronics.com/

Buy SMD tweezers. Get a flux pen for later builds with SMD ICs. If you don’t have some from existing projects, you’ll want desoldering wick.

For your first build, do a Bong0, then a BOOLs. The Bong0 is probably $1 worth of parts, tops. It took me around an hour to build and calibrate one. BOOLs is also cheap, but there is more to solder. The best thing about those two builds is that they do not have SMD ICs or transistors, which are far-and-away the toughest parts. Both can be sourced entirely from Tayda. Brain Custard is a good next step, as it introduces SMD ICs that can still be bought from Tayda. The 1050 Mix Seq is intimidating, but it’s probably the next step after that. It introduces SMD ICs which you’ll need to source from Mouser. Most of the newest NLCs builds fall in the 1050 range: order 98% from Tayda, buy a small handful of parts from Mouser.

As a beginner, avoid Feague, FlipFlop Chaos, the new Sloths, and the Phaser. They can still be built with Tayda and Mouser parts, but you’ll need to track down a lot more parts beyond ICs. Sloths and FFChaos have a bunch of weird resistor values, the Phaser has transistor matching, and for Feague you’ll need to chase down a tempco resistor along with some other expensive parts.

@Jonny, I hate saying it, but the Microbraids is a beast to build. The ICs are tiny, and the resistors/capacitors are 0603. Start with an 0805 project if possible. Also, for 0603 builds, you’ll want to buy a smaller tip for your iron. O+C is much easier than Microbraids, but the DAC is a real pain. That DAC is a good introduction to Microbraids, which has a large number of ICs like that (and worse!).

trickyflemming · 2017-03-03T01:40:20.045Z

Forgot to mention, this is the best SMD starter project:

Thonk - DIY Synthesizer Kits & Components – 19 Jul 18

Music Thing Modular – Simple EQ – Full Kit

This full kit is great for learning SMD/Surface mount soldering. Build a super skiff friendly and great sounding EQ module. We have produced a new revision of this MTM board which includes a few…

Everything is in the kit, plus it comes with detailed instructions.

Galapagoose · 2017-03-03T01:49:48.761Z

I’d agree with most of the above. Personally I think 0603 is pretty much the same as 0805 in terms of difficulty – I went from TH straight to 0603 and find the SMT process less fiddly than through-hole overall.

Agreed that you don’t want to start with anything smaller than a SOIC IC. The pins on those chips are pitched at half the size of a through-hole DIP chip, so shouldn’t be too terrifying. A proper PCB with good soldermask (basically every board available these days) actually makes it pretty difficult to mess up the chips. When you do end up with too much solder & a bridge, solder-wick is the easiest way to remove some (not all) of the solder.

Buy a flux pen - it is almost essential for SMT builds imo. You just draw a line across the row of pins you want to solder before putting the IC in place – the pins almost solder themselves. I’ve always used the standard hakko / weller iron tips and find them totally fine for SMT work (even tiny parts).

Definitely steer clear of the digital projects at first with pins smaller than 0.05" pitch. These are not that difficult, but require a different technique to work with. It’s a kind of combination of the other SMT approaches (something like: flux, tack-solder, lots-of-solder, wick, flux, touch-up). Hence 2nd or 3rd project, and you’ll want to buy an extra chip or two of the small ones.

Jonny · 2017-03-03T03:14:25.315Z

@trickyflemming - yeah, I know I’m probably biting off more than I can chew with Microbraids, but I figure I have to jump into the water at some point…

rbxbx · 2017-03-03T03:58:01.189Z

ordered one! thanks for the tip.

trickyflemming · 2017-03-03T04:42:30.678Z

Other SMD suggestions:
-Always order at least 2 or 3 more resistors and capacitors than you need for a project. If you drop an 0603 or 0805 part, you’re likely never going to find it.
-When ordering from Mouser, always check the bulk prices. It’s typically cheaper to order 10 resistors than 4.
-For your first Tayda order, I’d order 100 each of 1k, 10k, 100k, 47k, 220k, and 470k resistors. I’d also order 50-100 of .01 uf (10 nf) and .1 uf (100 nf) capacitors. If you’re planning on building a lot of NLC projects, he uses a ton of b100k pots for his modules. Mutable builds have a lot of b10k.

The Tayda Davies clone knobs (https://www.taydaelectronics.com/knob-davies-1900h-clone-black.html) go with these pots: https://www.taydaelectronics.com/100k-ohm-linear-taper-potentiometer-round-shaft-pcb-9mm.html
Don’t buy the cheaper pots. These have nuts that secure the PCB in a stronger fashion.

The Tayda jacks (https://www.taydaelectronics.com/3-5mm-mono-enclosed-socket.html) are cheap and tempting. They’re unfortunately noticeably lower quality. Thonkiconn jacks (http://modularaddict.com/pj301m12-jacks) are much higher quality and actually make the builds easier in almost every case. There are a few older NLC projects (Neuron and Chopper come to mind) where the Thonkiconns are way more difficult to install than the Tayda jacks due to weird PCB layout choices.

Don’t forget to order power cables: http://modularaddict.com/parts/synth-diy-parts/eurorack-power-cables-732

These are essential for mounting knobs onto pots: https://smile.amazon.com/Stanley-66-052-6-Piece-Precision-Screwdriver/dp/B00009OYGV/ref=sr_1_5?ie=UTF8&qid=1488515481&sr=8-5&keywords=stanley+screwdrivers (They’re also useful for screwing modules in and out of the rack. The form factor is great)

I use these tweezers: https://smile.amazon.com/gp/product/B00XRKPCJE/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 (mainly the ESD-15)

I use this flux pen:

amazon.com

SRA #312 Soldering Flux Pen Low-Solids, No-Clean 10ml - Refillable - - Amazon.com

As @Galapagoose said, don’t skip the flux pen.

infovore · 2017-03-03T07:59:19.559Z

Larrea:

If I have to source parts from all over creation, this is a total non-starter for me. But if someone sells me every single thing I need in one bag, I’m in.

This is probably a non-starter for you, then. There are a few SMD kits: the few Music Thing ones that use it, all of Nobots stuff, some forthcoming ones from me. Most of the time, SMD boards are aimed at people comfortable sourcing parts.

Sourcing parts is straightforward and part of the DIY process, but I understand if you don’t want to get into this. I’ll reply elsewhere to the rest. (I’d add: you aren’t going to be “sourcing parts from all over”; by and large, you should be able to get everything from a single supplier. Some projects even link to BOMs - “Bill of Materials” - at a supplier so you just click ‘add to cart’. The big electronics stores - Mouser, Farnell, Digikey - sell everything.

infovore · 2017-03-03T08:03:04.742Z

Microbraids is a REALLY tough first build. I’m honestly going to echo that here.

it’s small
it has two different MCUs with different platforms to flash
it’s a tiny bit of a hack
it was already based on something that wasn’t designed for “civilian” manufacture.

I think this is a key thing to understand about SMD: SMD is totally buildable by hand, but there’s a difference between “SMD designed for people to make” and “SMD for machines to make that you can also make if you want.” Designers often end up doing the latter as prototypes, but it doesn’t make it easy.

SOIC chips are fine - the thing you have to remember is how solder flows. It doesn’t go everywhere. There’s flux in a pen, flux in the solder itself often, and soldermask on the board. It is quite easy to shape where it should go and clear up.

Smaller ICs, though: yes, those are hard, and were never really intended for irons.

infovore · 2017-03-03T08:07:06.894Z

So most of the things I’d normally say have already been posted here. My other tips would be:

big iron, fine solder. I’m fine with a chisel tip - and like it for heat transfer - but moving to fine solder has made ICs much easier.
unlike through-hole, where you build up based on height, most stuff in SMD is the same height. So I tend to build the things that will prove hardest to get to first - often, ICs - and then do the simple passives around them later.
the “package” number that we’re all talking about indicates size. Larger is bigger. Most of my stuff (that I design for human manufacture) is 1206, but 806 is equally doable. I think < 806 is challenging - it all depends how jittery your hands are.

Oh, and because I don’t think it’s been mentioned: you don’t mention owning a multimeter. If you want to DIY, buy a multimeter. A cheap one even with autoranging is < $20. Being able to test voltages at points and continuity is critical for debugging builds - can’t believe how many “my DIY build doesn’t work” threads elsewhere start from a perspective of “oh I can’t test this, can you see what’s wrong from a photo?” They are endlessly useful.

tehn · 2017-03-03T12:58:41.117Z

@Galapagoose said everything i was going say! (no surprise)

geh2oman · 2017-03-03T15:10:16.547Z

To all of this which I mostly agree with and support, I would add that finding a good, fine width solder is also important for these builds, as getting the solder in with the tip and the part with the tweezers can be a little daunting at first. I find really easy-to-work-with .3mm solder on Amazon that I use.

Larrea · 2017-03-03T17:41:26.816Z

You guys are all completely heroic.

Incalculable thank yous.

Amazing I didn’t even know (although guessed) what a BOM is.

I surrender.

I will board the sourcing parts train. It’s clear now it’s the way forward.

I guess I was scarred by my early teens a generation and a half ago, when I had to etch my own circuit board off of some crude thing I drew, and had nothing but a schematic from Craig Anderton’s book, or wherever, and had to figure it all out, and bribe my mom or someone to drive me to the stupid Radio Shack or Henry Radio or whatever to scrounge up the parts, and then put the whole thing together somehow in an old MXR box, because no munnies to buy a fancy metal box…etc.

Okay, this is easier.

I had to look up SOIC and those numbers, but it’s all what I suspected–sizes.

Galapagoose · 2017-03-03T18:04:39.335Z

One last thing. Maybe it’s controversial, but if you want to do the small stuff, you really want to use leaded solder. I haven’t read anything overly convincing that says Pb-free solder is better for the environment (lots of crazy chemicals in unleaded solder!), and the difference is truly massive.

Obviously production is different, and thankfully the machines are designed for the no-lead process!

Larrea · 2017-03-03T18:32:23.315Z

Sold on that.

Dumb follow-up: if I’m using a flux pen, do I still need rosin core?

There are lots of .3 solders I see on Amazon. Anyone want to recommend a particular one? Best is best.

tehn · 2017-03-03T18:59:07.760Z

in my efforts not to buy from amazon, i get these sorts of supplies from sparkfun or adafruit. basically since they curate their small stock you can be assured they are worthy products.

ie “best solder in the world” allegedly, we use it:

sparkfun.com

Solder - 1/4lb Spool (0.032") Special Blend - TOL-10243 - SparkFun Electronics

We don't want to hype this solder TOO much, but this could possibly be the best solder in the world. There, we've said it. This is a special blend made spe

of course this is marketing. but seriously, despite the amount of soldering we do i have no desire to spend hours researching and comparison testing solders!

Larrea · 2017-03-03T19:06:42.381Z

Thank you; this is great.

I’m going to use those sources, as, as it is with you, I don’t like Amazon. In fact, I was planning on closing my account completely this week. I used it once recently to purchase a RAV battery, but after enquiring with RAV for alternatives, for the model I needed, it was the only source.

I forgot about Adafruit. In fact, I have an account there already from some stuff I purchased several years ago.

frankchannel · 2017-03-03T20:08:06.979Z

No one has mentioned using hot air and solder paste. I find this method is really easy and effective too. I picked up a cheap reflow hot air gun on eBay for about $50. You can also get stencils cut for your PCB cheaply from OSHStencils, which makes it really easy to apply the solder paste neatly (although it’s not necessary). I used this technique to solder the 256 LEDs on my DIY Arc, which made the process pretty easy – just apply the paste, place all the parts, and torch the thing.

Also, having a hot air gun makes it pretty easy to desolder parts (I always find solder wick and solder suckers to be a real pain to use).