I'm needing to get some basic tools for surface mount stuff. Already have a heat gun and soldering station plus basic electronic instruments, meters & scope.
Need magnifier, would the head band type or a clamp on arm lamp/magnifier be best? Or both?
I guess tweezers? Do you use some sort of paste to hold components or just hold them down and solder?
Any other items to consider? Panavise with circuit board holder?
Thanks
RogerN
Depends on you, I guess. Some people make a whole production out of it. I got by fine with magnifying glasses (strong reading glasses), a good strong light, a fine tip on a temperature controlled soldering iron, small-diameter multicore solder, and a good pair of tweezers. I did pick up a hot air iron with the income from the work I did with the first set of tools, but more for getting things off (rework) than for putting them on. Hot tweezers might be nice sometimes, but have not been worth the cost to me yet. I haven't used solder paste yet and have no plans to.
To put components on, tin one pad, solder device to that pad, solder pin in opposite corner (or other pin from 2-terminal devices), remelt first pin to relieve stresses, solder remaining pins.
-- Cats, coffee, chocolate...vices to live by
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I use a Metcal system with an STSS power unit, MX-500 handpiece and MX-500 cartridges. I use a powerful pair of reading glasses or a stereo microscope for magnification.
Leon
It's not so much the tools but the technique. I ws doing some 402's quite easy with just a normal iron and tweezers. I did some 0.5mm pitch 32 pin QFN's with just an iron by presoldering(lightly) the pads on the pcb and chip then heating the pads. I had problems at first and it's not perfect as sometimes you do nto get connections but it is not at all difficult with some practice. I had head band magnifying glasses of course but it is probably not needed.
The biggest problem you'll run into using this method is not getting a flush surface which causes the IC's to tilt and positing them(which isn't hard it seems as many times I was able to get them spot on the first attempt in a few seconds). The tilt is not a huge issue if it's not too bad but it allows more solder to get in between the pads which can cause shorts.
Again, it's not has hard as it might seem at first thought and once you do a few and figure it out it comes an order of magnitude easier.
For the QFN's,
I would pre-solder the pads ever so slightly(using a lot of flux and the solder on the tip rather than from wire). Put a lot of flux on the pads and position the ic using tweezers and line up the pads on all sides. Head up a few traces connected to the pad to melt the solder and hopefully form a bond. If done it will anchor the ic so that you won't move it if you bump into it with the iron. Then it's just a matter of using solder on the pads and drawing the iron across them. You can easily tell when the pad's "take" the solder as it will form a "knee". If you have issues with opens or shorts it's usually just a matter of running the iron with a bit more solder across them. I did not pre-solder the thermal pad as this almost always created a large tilt making it difficult to keep the pins from shorting. A hot air gun helps a lot to remove ic's that you screwed up. out of about 30 QFN's I had major problems only about 3 times. All the other problems were simple fixes by drawing the iron across the pads with a little more solder and flux.
If your only doing this for hobbby, then magnifier on a head band will work. Fine tip soldering iron and small solder (10 or 15 mil diameter) and flux. If you need to solder parts with hidden thermal pads, toaster oven or waffle iron (with fippable plates for grilling sandwiches). Waffle iron works better than toaster oven unless you have really tall parts.
If you are doing SMT work often (not production), I'll recommend:
-- Mark
Forgot about tweezers. I like smooth fine tip for small parts. Serrated tips are nice for large parts like SO8. The serrated tips are usually pretty large, so I grid the thickness down so I can get in tight places.
qrk wrote in news: snipped-for-privacy@4ax.com:
I've used the head-band type of binoc magnifier,and they're a PITA.
I much prefer a clip-on binocular magnifier;it's the binoc lens from the head-band type,but without the restrictive headband frame. You can look around the magnifier,you can use it with bifocals or with the supplied lensless frame.
I'd suggest a vacuum desoldering iron/station. the solder-suckers and solder wick can easily remove the pads along with the solder.
-- Jim Yanik jyanik at localnet dot com
Am 31.01.2010 18:17, schrieb RogerN:
What kind of SMT? SO-8 is as simple as DIL-8 except you don't have to drill holes.
BGA is really hard to handle. QFN is a pain, TQFP is almost simple.
Resistors and the like smaller than 0603 are ok (if it's visible, it can be soldered), except when it falls down to the floor. You will not find it, forget it ;-)
I have both but I only use the arm lamp/magnifier (from Ebay for ~50¤). People told me, that USB microscopes are very good for small parts and checks (~50¤).
Yes, but for larger components positioning can be better using your finger.
...
My brother's father-in-law, a watchmaker, recommends to put the parts you are working on, as close to your eyes as possible. The height of chin or nose ist best. Make sure your hands have support. Four Digikey catalogs are ok ;-)
Have fun, Falk,
Bad idea because of the resin from the solder splattering around.
I see a lot of people advising thin solder and fine tips. I advise against that. Use flux and all you can use thick solder and a thick soldering tip and make better solder joints. A fine soldering tip cannot transfer enough heat even if the part or pin is very small. The whole trick of soldering fine pitch is not to solder pin by pin but solder a few pins at the same time and let the flux do the hard work.
-- Failure does not prove something is impossible, failure simply indicates you are not using the right tools... nico@nctdevpuntnl (punt=.) --------------------------------------------------------------
Ok, I assumed that there is some kind of lens between solder and eyes.
I agree to that. But a fine tip (#8) on my 30 years old 35W Weller is doing much better than a 3mm tip on a new 50W electronically regulated (cheap) soldering station.
Without a solder mask on self made PCBs I don't want to rely on the flux doing the hard work.
Falk
So you don't know how to use one properly. That shouldn't guide the use of other people. You don't poke the point in, you lay the side of the cone on. Full heat to single pins, no problem. Turn 90 degrees if you want full heat to multiple pins. If there's no soldermask, your method can get very messy very fast. Even if there is soldermask, it has limitations which the properly applied fine point does not. If you use a fine point improperly, you'll do about as well as people that use a wide tip improperly. By all means, keep doing what you like, but your one true way - isn't.
-- Cats, coffee, chocolate...vices to live by
Most of the time for gullwings you can apply enough solder to bridge the pins then wick up the excess solder quite easily. My method is simply to clean the tip each time and the excess solder wicks up on the tip. If you presolder the pads then it generally isn't an issue either way.
The guys at Sparkfun.com did a test for reflow stuff and they found what I believe was a Rival electric skillet that did the best job and could be had for short money.
As far as soldering goes, I use the MPJA temp controlled iron. The whole kit (Iron, base, additional tips, tweezers, etc.) will run you < $100.
Light binocular magnifier:
BTW, a similar approach works for QFN's but is a bit more difficult.
When buying parts for prototypes buy a few more of all the small parts so you can just get a new one when one pings off (it doesn't take a lot of force when opening packaging to
When buying parts for prototypes buy a few more of all the small parts so you can just get a new one when one pings off. (It doesn't take a lot of force when opening packaging to do this).
Nial.
Am 02.02.2010 13:50, schrieb Nial Stewart:
Plus two for accidentially leaving the SOA, plus two for accidents during soldering....
Friendly components send smoke signals or unsolder on failure ;-)
Falk
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Hi Roger, I'm a repair technician in Corona, CA. I repair cellphone circuit boards. The best tool that I use for smt is a preheater (QK853), a small pcb stand, a QK989 w/ SD04B base ( tweezer w/ soldering station, a usb camera, microscope and a desoldering station. This whole complete setup does the whole application I need to get my work done. I found a business similar to Madell but it's called SMTmax.
Paul
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