Prototyping boards with small SMT components

I use a suction lifter made from a rubber ball and hypo needle with the end ground off and dipped in PVA and allowed to dry.

I have also tried your technique and I must admit that it is actually easier than trying to manoeuvre a rubber ball with a needle stuck out of it !

My problem is shaky shaky ! Your technique only solves half of that for me. :-)

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Best Regards:
                     Baron.

Hi Don,

I use tweezers to handle the parts - no problem down to 0603, never tried 0402 but see no problem here either.

Someone or othe posts the method I use every month or so - but just in case you have missed it:

• Turn on your bright light

• Put on geek magnifier headband

• Tin one pad (a corner one for many-pad parts)

• Pick up part with tweezers

• Hold soldering iron to tinned pad, melting the solder

• Move part into position with tweezers

• Remove iron

• Let go of part

• Solder reminaing pins

• touch up original pin if required.

Advanced users: You can develop techniques for efficiently soldering lots of pins very quickly by running a soldering iron bit down a compete row at a time. Adding lots of flux here usually helps a lot.

I occasionally have to replace a 176 pin 0.4mm pitch QFP. But that is indeed a PITA.

Tweezers!

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John Devereux

I don't do a lot but I've had pretty good success hand soldering 0.5 mm pitch TQFPs using the wipe and wick method.

Carefully tack in place, usually opposite corners. Flux up and then run a wave of solder down a row of pins. Flux up again and wick the whole row. Inspect for bridges.

NOT the most thermally gentle method but it works very well to, e.g., swap out a micro on a dev board that has too many entries on the errata sheet for a more recent production rev with none.

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Rich Webb     Norfolk, VA

I do DIY stencils using aluminum foil, then you can use plain pointy tweezers to place all the parts (they stick to the paste more than they stick to the tweezers) and reflow it on a $20 hotplate.

I do 0.5mm pitch by hand all the time, using a 1/8" chisel tip. The trick is to use plenty of flux and solder, and worry about bridges later (copper braid).

I use a tweezers (the kind you squeeze to open) with 0603-like components. (I've also found that, while 0402s can be done, there's a noticeable drop in productivity at that point.)

Sure... just get some very thin solder (e.g., 10mil diameter), lay it down across the line of pins, and with your soldering iron drag it across the solder to melt it on top of the pins. There are a few parts to this trick:

1) Flux everything up nicely first. I like those flux "pens." 2) You want to use a flat-bottomed ("hoof" shaped) tip, so that as you drag the iron along it keeps pushing solder in the direction you're dragging. 3) You watch how much solder is accumulating under the tip and draw back the solder when it starts getting to be too much so that pins don't get shorted.

When you done, you almost always end up with a few shorted pins at the end of the row, but a little soldering wick fixes this up. When you're just starting, you'll have a few more shorted pins that can also be cleaned up this way.

I've known people who skip adding their own solder to the row of pins, just relying on the solder already present on the board and the IC pins for connectivity. That's really not an awful lot of solder, so I've never been entirely comfortable with that approach, but I have seen others use such a technique successfully.

Although it's not necessary, this technique does work fine with SOIC packages as well and so you might practice with those.

On a "per pin" basis, soldering something like a TQFP-100 is much faster than any through-hole package you might find -- it's great.

If you do a little poking around on You Tube, you'll find lots of people with various slightly different methods for soldering fine-pitched components. Also check out the SparkFun guys:

.

---Joel

Can you elaborate a little on the Al foil stencils.

I looked at the information on your site, interesting, thanks.

[..........]

"As seen on Homebew_PCBs"

Laminate UV-sensitive photoresist to both sides. Expose, develop. Etch in your regular copper etchant. Warning - this is *fast* and somewhat energetic, just dip it in for a few seconds. Rinse and dry, do NOT strip the film. Between the foil and the two films, it's just the right thickness and strength for solder paste.

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I like to 'lightly' tin one pad. Place the component (with a nice stero microscope) hold down with tweezers and apply heat to tinned pad. If placement isn't good lift and try again. If placement is OK, then solder other pins and reflow first solder joint.

George H.

Yes. A bit daunting to get started with, but simple enough with a little practice and 1: eyewear (or a microscope, but I haven't gone there yet)

2: a finer iron tip 3: LIGHT!

Plain old fine-tip tweezers.

Yes, though they are certainly a pain - a lot ends up depending on solder surface tension. Plenty of flux a big iron is one approach - a tiny iron and optical devices (pretty much needed anyway for most of this) is the other. And the third would be the paste/oven approach, but I haven't tried it. Braid to suck out excess solder can help, but not using excess solder is better. For multi-pin packages, I'll get one pin at one corner nailed, then get the opposite corner nailed, then do the rest with it held in position by those two (and re-do them).

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Cats, coffee, chocolate...vices to live by

thanks DJ

0603:

easy - tweezers and TC iron with small bit, tin one pad first.

0.5mm pitch ICs: I use an iron with a tiny hole in the centre of the bit (from Ersa), 20x binocular microscope and plenty of flux (not from a pen but from a bottle and applied with a brush). With this setup I can solder 0.5mm pitch easily and averge about 1 solder bridge per 144 pins. Most bridges can be cleared by using the special bit empty to suck out the solder - I only every resort to the braid after a big screw up. If I just want to remove large QFP I cut the leads with a scalpel - with a new blade almost no pressure is needed and only a few strokes.

As many others have mentioned the key is flux - I use Warton Metals Future

315 from Rapid Electronics Ltd (UK) - clear, low residue, comes in bottles. I clean boards with Safewash in a little Chinese Ultrasonic bath and rinse manyy times with de-ionised water.

Michael Kellett

0402's are not hard but they are fiddly which takes a lot more assembly time and care, best done under a magnifying lamp. Best avoided for boards you know will be hand assembled.

The standard technique is to simply apply solder to one pad and tack the component in place. Then all the other pins are easily soldered with fine solder (0.56mm or less) and a small chisel tip.

Yep, easy. 0.5mm pitch gets fiddly though. The key is a good solder mask. Large multiple hundred pin TQFP's aren't hard either. There are tutorials around on ways to this. One method is using a concave "wicking" tip and lots of solder, relying on the solder mask of course.

Anyone who can't do say 0805 easily by eye shouldn't really be doing any soldering!

0603 is almost as easy.

Good SMD tweezers are absolutely essential.

It also helps a lot to have component footprints that are "hand solder compatible". i.e. oversize with extra pad area for the iron to access.

Dave.

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I do the "tin a corner pad and tack part held in tweezers" technique under a stereo microscope using a Metcal iron with 15 mil solder. No problem working with 0402 parts, but I would prefer 0603. 0805 seems huge these days. If you need to do 0.5mm pitch parts, flux will make things go smoothly.

I use a waffle iron with flippable grill (for sandwiches, I guess) for parts with thermal pads. Works better than the toaster oven techniques.

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Mark