Maybe OT: Why so much resistance to SMD?

[tiges_ tendres]

My resistance to smd has been that it's a little confusing.  How many different sizes of SMD exist?  The costs aspect I like, but from the little I've done, it's a bit fiddly. 

I think also for those that build and sell their pedals, aside from digital stuff there is an undeserved stigma attached to SMD construction that guitarists think it doesn't sound as good.  Not really a big selling point for a boutique builder.

[Gordo]

Not really a big selling point for a boutique builder.

Yeah, that's true. Does anyone have a link to how to work with the stuff? Solder paste, hot air iron etc? My eyes are shot to the point where I work with a magnifier anyway so bumping it up a notch might not be difficult.  Those itty-bitty little parts though...

[jacobyjd]

I'm with the perf/vero guys. I don't really have a reasonable location in which to perform etchings (small apartment, iffy ventilation, etc.), so I generally  go the perf/vero route.

[defaced]

Not really a big selling point for a boutique builder.

Yeah, that's true. Does anyone have a link to how to work with the stuff? Solder paste, hot air iron etc? My eyes are shot to the point where I work with a magnifier anyway so bumping it up a notch might not be difficult.  Those itty-bitty little parts though...

spark fun elctronics has some great tutorials on working with smd. I use a standard soldering station and solder. Paste is for automated work. An air station is good if you need to remove ICs.

[Johan]

why  o SMD...no GE-transistors...just kidding....my main complaint would be it's so much harder to modify/"cut and paste" on an allready stuffed board...I've done years and years of SMD board repairs and have no problem soldering the little buggers(including 128pin processors), but for our purposes I dont see the point..our circuits are small and simple ..and they look silly on a smaller than a stamp-boards...and beside, I like legs..
J

[Gurner]

My eyes are shot to the point where I work with a magnifier anyway so bumping it up a notch might not be difficult.  Those itty-bitty little parts though...

If your eyes are starting to fail (mine are!) ...then it's likely your hand isn't as steady as it was (mine isn't!)....and contrary to what you might think SMD can be easier ....but you'd need to go the solder paste route - then capillary action becomes your best buddy!

Basically dispense a tiny bit of paste onto the PCB pad for each component location (like I say I use a pneumatic paste dispenser & a desktop mounted illuminated magnifiying glass)...plop your components on (they don't have to align that well)....slap the board in a cheap benchtop kitchen oven (should have a fan  - and needs to be dedicated for your hobby ....don't cook stuff in their too!), turn it on....after about 90 seconds, marvel at all the components self aligning themselves as the solder paste flows.

Remove, & be amazed at how everything aligned so well.

The oven temperature is meant to follow a temperature 'profile', and when I first began, I made sure I monitored the temperature with a thermocouple...into a DVM (with temp capabilities) so I could manually control the temperature to mimic the desired 'temperature profile' but after a while I decided that it was a load of old bollocks & now just watch for the solder to flow after about 90 seconds!

Type 1206 SMD resistors & caps are not that small....easy enough to handle with the right kit (good pair of tweezers)

[Morocotopo]

Never did a SMD thing, but it looks to me that the difficult part woud be making the PCB! Tighter tolerances... Iron-on transfer methods aren´t too precise (PnP, magazine paper, etc etc)... How do you small people (err, I mean SMD people) make the PCB´s?

[Gurner]

Never did a SMD thing, but it looks to me that the difficult part woud be making the PCB! Tighter tolerances... Iron-on transfer methods aren´t too precise (PnP, magazine paper, etc etc)... How do you small people (err, I mean SMD people) make the PCB´s?

I leave irons to my wife - never touch the things ...I don't understand them (do you find yourself straying onto shopping channels when making PCBs this way?)

Eagle->laser printer-> homemade UV box (pre sensitized board) ->caustic soda->ferric chloride .... Job done (I can work down to 0.65mm pitch.....0.5mm pitch is just taking the p1ss)

[therecordingart]

Do you SMD guys use a conformal coating or tin plating on your boards?

[Brymus]

I have no resistance to SMD.
In fact I would really like to learn how to solder those little buggers properly and save money on parts and high speed bits.
I have seen some serious SMD kits for not alot of cash on the bay.
Aside from the fact that most modern designs utilize SMD components,I would like to make something cool that would fit in my guitar cavity without extra routing or drilling.

[amptramp]

I have worked on both through-hole and SMD and one disadvantage of SMD for small components that has not been mentioned is the lack of strain relief.  If you flex a through-hole board, nothing happens because the leads bend.  If you flex an SMD board, devices lose contact or fall off.  Leadless components (passives and leadless IC's) do not work very well over the temperature range you would expect to see as a touring musician.  As a studio queen, they may be OK.  Gullwing devices are generally OK.  Over the temperature range, the temperature coefficient of the circuit board is much larger than the ceramic components.  The most important thing to design for is abuse and they do not tolerate much of it.  Quite often you get intermittent connections that work some of the time but are simply pushed together with a fractured solder connection.  Through hole may have this problem, but it would be the quality of the solder joint, not the fundamental design that is at fault.

[Electron Tornado]

 I have an old board with some SMD to get some practice soldering, but I haven't really worked with SMD yet. It would increase the stuff I would consider working on.

With SMD I guess you could still use vero, but it seems more limiting to the point that you're almost forced into etching a PCB. With through hole parts, you can use perf, vero, or a PCB. 

For those using solder paste and an oven - what temperature is used, and do you ever have thermal damage to any components?

[amptramp]

I have an old board with some SMD to get some practice soldering, but I haven't really worked with SMD yet. It would increase the stuff I would consider working on.

With SMD I guess you could still use vero, but it seems more limiting to the point that you're almost forced into etching a PCB. With through hole parts, you can use perf, vero, or a PCB. 

For those using solder paste and an oven - what temperature is used, and do you ever have thermal damage to any components?

A lot of SMD components have a temperature vs. time soldering profile as part of their specification.  You cannot put a board in an oven and turn it on without killing components or getting cold solder joints.  You have to have the oven up to temperature.  SMD components are usually soldered using vapour-phase equipment or infrared ovens with a conveyor that moves the board past certain temperature spots with a defined temp vs. time profile.  For the individual experimenter, it is better to solder the parts using a fine-point iron.

[davent]

It's all about the aesthetic, I find a well laid out, populated through hole board a thing of beauty, a mini piece of architecture. a miniature cityscape. I don't get the same buzz from a SMD board, impressive but rather plain and boring by comparison.

Found this tutorial helpful on the road to SMD work.
http://tangentsoft.net/elec/movies/tt03.html

dave

[joegagan]

call me a dinosaur. i want my tone flowing through large bits of metal wherever possible. someone could show me 500 pages of data proving why tiny parts cannot electronically be inferior to larger components, my old guy brain still wants to believe.

a good friend of mine built two versions of the same popular OD pedal . one used small parts , the other used amplifier sized caps, wire, etc.

guess which one sounded bigger and better?

why does zvex avoid opamps for signal path wherever possible?

jack orman told me years ago that caps of different construction could not possibly sound any different from each other. my ears told me a different story in tightly controlled (ear)testing.

signed,
the 50 year old.

[Gurner]

I have an old board with some SMD to get some practice soldering, but I haven't really worked with SMD yet. It would increase the stuff I would consider working on.

With SMD I guess you could still use vero, but it seems more limiting to the point that you're almost forced into etching a PCB. With through hole parts, you can use perf, vero, or a PCB. 

For those using solder paste and an oven - what temperature is used, and do you ever have thermal damage to any components?

A lot of SMD components have a temperature vs. time soldering profile as part of their specification.  You cannot put a board in an oven and turn it on without killing components or getting cold solder joints.  You have to have the oven up to temperature.  SMD components are usually soldered using vapour-phase equipment or infrared ovens with a conveyor that moves the board past certain temperature spots with a defined temp vs. time profile.  For the individual experimenter, it is better to solder the parts using a fine-point iron.

Like I say, I initially used a thermocouple in sa bog standard bench top kitchen mini (pizza) oven .....I'd try to ramp the temperature up in accordance with the profile. (bit of a faff, adjusting the oven on/off switch, opening the door to vent off extra heat etc!). But now I set the temp to about 190C, turn it on & watch the solder reflow at about 180C (takes a couple of minutes to get to this heat).....give it about 20-30 seconds to reflow, then open the door.

Whilst I concur, this would not be up to commercial standards, but I've had no component failure or bad joints arising from this method (a couple of dry joints where I hadn't sipensed enough paste....but they're easy to spot)

[DougH]

call me a dinosaur. i want my tone flowing through large bits of metal wherever possible. someone could show me 500 pages of data proving why tiny parts cannot electronically be inferior to larger components, my old guy brain still wants to believe.

a good friend of mine built two versions of the same popular OD pedal . one used small parts , the other used amplifier sized caps, wire, etc.

guess which one sounded bigger and better?

why does zvex avoid opamps for signal path wherever possible?

jack orman told me years ago that caps of different construction could not possibly sound any different from each other. my ears told me a different story in tightly controlled (ear)testing.

signed,
the 50 year old.

Did you measure all the part values before hand and make sure they matched?

[Electron Tornado]

Thanks to both amptramp and Gurner for the replies. I'll have to try both methods with a defunct PCB with some SMD parts on it.

Making a PCB for a project using SMD would be a bit of a challenge to get pads small enough and close enough, and making sure to get a etch resistant that is consistent and reliable.

[DougH]

The reason I'm not interested in SMD is because I'm not interested in using PCBs for hobby builds. I prefer perf so that puts me in the "no SMD" camp by definition. Otherwise I don't have much of an opinion about it one way or another.

[slacker]

That's exactly my position Doug.

Thinking about it I'm not sure there is much actual resistance to it, it's more just the case that for hobbyists it doesn't really offer any advantages. I've yet to see a project anywhere, not just here, that couldn't just as easily be built using through hole. The only thing that tempts me to use it is the Spin FV1 chip, but even then I'd probably just use an SMD to DIP converter and do everything else through hole.