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Author Topic: technique for neat smd components?  (Read 1576 times)
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What are you guy's technique for nice neat soldering of smd components, mainly like resistors and leds which are pretty hard to hold still
my attempt is either put some solder on the pad first then press the component down and solder or I attempt to hold it in place and solder it
either way it never ends up straight, and sometimes not flat, 
Any better techniques or do I just need a steadier hand lol
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Tiny spot of superglue, place component and let it harden, then solder.  You have to be careful of the fumes though, a fan to blow them away from you is useful, cyanide is not good for you!  Alternatively there's the tack soldering you mention...

Good tweezers are essential, good magnifier, very fine soldering iron bit, temperature controlled iron.  You can get rosin pens too to prime the pads.
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I've used superglue on other things before and it leaves like a white residue around it, is that corrosive? That's probably the only reason why I haven't tried it yet, since idk what that is
And yeah I've teared from thos fumes pretty good once, I was glueing leds under my car dash, and there's not much ventilation down there upside down lol
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If you're doing it all by hand, then you're already doing some of it right.  Tin one pad first.  Put some flux on it and put the components ontop.  I use tack flux so it also holds the components in place (at least till it flows.)  You can use a pair of tweezers to hold it in place while you heat up the pad again and let the solder flow and grab the components.  Let it cool.  Now add some flux on the other side, put some tin on your iron and touch the other side.  I've never used super glue with this technique.

Of course, I have also moved away from doing SMD by hand now, I do it all by skillet relflow.  SparkFun has a tutorial on that.  It's easy, fast, and much cleaner results.

Also on the fan, don't have it blow onto your project.  You'll be cooling both your iron as well as the parts as you're trying to solder them on.  Flip it around and have it suck the fumes away.  I have a bench ATX power supply from an old computer with two fans connected to it.  They both sit close to my helping hands so they can suck the fumes away.
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You have to be careful of the fumes though, a fan to blow them away from you is useful, cyanide is not good for you!  

Yes, the fumes are not healthy and cyanide is very bad for you of course. However cyanoacrylates do not contain any cyanide at all http://en.wikipedia.org/wiki/Cyanoacrylates#Toxicity.

With regard to the original question: what about this solution http://www.g0ghk.co.uk/a-soldering-aid-for-smd-components-by-dave-g3vze.
« Last Edit: February 22, 2012, 04:43:14 pm by Udo Klein » Logged

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Any better techniques or do I just need a steadier hand
More practice. Practice makes perfect.
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Me, I use tape. Any type of tapes. Scotch tape, masking tape, black tape... take your pick.

The smt is sticking to the tape, place the tape / smt part at the soldering location, oriented the part, solder one end, remove tape and solder the other end. You are done.
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I can see tape working for 0805 parts, but as you get smaller, I can't see it working too well.
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I can see what you mean... smiley-roll
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Im gonna try the crazy glue as well as the solder paste reflow thing
I've got a board coming in probably a month from batchpcb with I think 32 0805 leds, and something like 45 0805 resistors and caps, and it looked so nice in the gerber to have as much as I can straight and neat so ill see how it ends up,
the soldering aid looks cool and I may built that if I findsome scrap wood/metal
I have crazy glue so ill do a small test with that, I also got 40g solderpaste(6$) from ebay so ill try that, just not with the whole 30$ stencil thing, ill try my luck with maybe an eye dropper or something similiar and then pop it in the oven while my moms not lookin
I think I need to buy a nice pair of tweezers, needlenose pliers seem so much larger compared to a 0805 resistor lol
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You need these, or similar.

For that kind of quantity on a board, I'd reflow it. Ohararp makes $25 stencils (plus shipping).  Or you can try to cut your own by hand ... been there, done that.
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I order stencils from pololu. I find the prices quite attractive. A $40 toaster oven from amazon does the rest. Techni-tool and other places offer solder-paste with and without lead. My understanding is that leaded paste is more forgiving but the fumes may or may not be bad for you.

I simply pre-heat the oven, then put the board in on high heat (toaster setting) with the board suspended in the middle of the oven cavity. When the solder paste turns shiny and liquifies, I turn off the heat, wait a bit, then pull the oven door open and allow the board to cool down. Has worked great and the stencils are a lot faster than tack-soldering.

Another issue with tack soldering small SMD components is the conductivity of the part - you may need to be really quick to prevent the heat transfer through the part from softening the solder connection on the other end of the component. I tried, and I gave up - 0805 - sized components were simply too much of a challenge for me. I suppose if I had a narrower tip and thinner solder, it might have worked better but with some of the solder landings underneath the components, solder paste is the way to go IMO.

Last but not least, another way to use solder paste minus a toaster oven or skillet on a  hot plate is to use the paste (you can even apply it without a stencil by using a fine tip and a plunger) and then a hot air gun to melt and solidify the solder paste.
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At my new work I had to crash course into SMD soldering real quick (like an hour quick, though I have messed with it a bit before), after hundreds of parts where 603 seems huge now, in a few days I havent mastered it, but I am getting consistent results.

What I have been doing is adding solder to the pad and wicking almost all of it away (or using stupid thin solder you can get a thin coat without the wick) .  Flux the part and then tack it to the pad,then going to the other side and soldering, then back to the first and soldering it for real real (not for play play). if you dont have 2 domes of solder its real easy to get them flat against the board and no / looking parts.

when I am doing SMD on a perfboard (which is quite doable for may parts) I just put a little ball of solder on each pad that the part will fit between and float the part on top.

today I was struggling with some no lead LED's, then I tinned the pads of the part, tinned the pads of the board, set the led where it was just on the edge of the pads, heated them both up and watched as the LED sucked itself into place, much quicker and much better results on that case.

as far as irons I just use a normal sized chisel tip at home and at work
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Im gonna try that toaster oven way, I know there's one somewhere around here
quick ques. Is it better to have it preheated or to let the board in there as it rises?
im gonna make an attempt at placing the paste with a fine applicator, ( im thinking a empty syringe my brother throws out all the time he uses with his diabetes, ill just take of the needle and use the small end as an applicator)
I really don't feel likespending money on a stencil ill use once, maybe twice max
I don't mind being patient with the applicator, the main goal is neatness not time,
when I first tried the 0805 leds my problem was that I thought it would stay still as I solder it if I was delicate enough, ends up the leds sticks to the tip and 3 sec later its burnt lol, atleast I've gotten past that tho
btw what's smaller than 603? Im afraid to even imagine
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btw what's smaller than 603?

Tiny. There's 0402s and even 0201s, but check this one out:

http://search.digikey.com/us/en/products/ERJ-XGNJ102Y/P1.0KAWCT-ND/1840179

2/10ths of a millimeter? No thanks, I'll leave those to the robots.
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