good, inexpensive hot air station?

Try one of the Faux affiliates.

It was too good a setup :)

If the EE lab doesn't have a hot air station, you should lobby them to get one. You can do a lot of work with a hot plate preheater and a butane pencil hot air gun. I have a "real" hot air gun, but I never bother to get it out of the drawer.

I think that if I were contemplating a big purchase, I'd wait for the dust to settle on this lead-free stuff and get a station that can do lead-free BGAs with vacuum pencil, etc.

mike

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This one works very well - perhaps you can find one used on eBay... I use it on 0.5mm LQFP's.

If you have ground planes, you'll find that a pre-heater is nearly mandatory. These are pricey, but they work very well, particularly if you have parts on the bottom that would interfere with a heating plate.

If you can find one used to meet your budget, highly recommended.

Richard

Yeh.. try the politician brand.. hedge.. er no,... bush.. mabe.. LOL

One chinese brand is Aoyue. Their stuff is cheap, and in particular the nozzle prices are reasonable. Many of the 'name' brands rip you off, and then ship stuff that looks remarkably similar to the chinese !

For me, I've decided that hot air is not the way to go for rework - too many problems with uneven heating and stuff being blown out of place ! I've now got a far infra red system (Aoyue 710) which is much better behaved, and doesn't need nozzles. Looking at it, I don't think that it would be a huge job to make one, once you have bought the special infra red lamp - available as a spare ...

Don't try and use any of these systems without a back side pre-heater - ideally you want the backside to reach something like (solder melting point - 20C), and then the top gun (hot air or infra red) supplies the rest. Note also that using a (gel) flux even when removing seems to be a good idea - it appears to play some part in transferring the heat around.

Dave

...

The flux helps the solder wet the joint because it eats the oxide(s) and exposes clean metal. :-)

Cheers! Rich

Flux improves solder joints by

A. Cleaning the metal B. Improving heat transfer C. Protecting the hot joint from oxidation

When I took my Navy soldering class, the correct answer was D: All of the above.

So I'd have to get a back side pre heater (something I've never even heard of) in addition to the hot air station? This is starting to sound really expensive.

All I want to do is be able to solder really nasty little parts (IE QFNs and DFNs). Is this not the correct route for me to take? Any other good methods for soldering teeny chips like these?

Thanks,

-Michael

I've seen a couple old Wellers at the EE labs that I currently have access to (read: not many). I'll ask around when I get back on campus though (3 weeks) - maybe they're just in hiding or something, though I doubt it. For some reason everything they do here (at least that I've seen) is with through hole parts. Bleh.

-Michael

I think the air stations are designed only to add the incremental amount of heat needed to melt the solder, not bring it up from room temperature. I'm not sure you'd have good results using an air pencil without a pre-heater.

And if your work involves ground planes, without a pre-heater you will have a hard time even with a big iron. A via or pad connected to the plane will sink an awful lot of heat, requiring more heat on the joint than the chip is rated, and making it very difficult to get a nice joint.

The toaster oven method is quite popular, since it tackles all sorts of parts for a much lower cost. A lot of folks have had good results with it, some even doing BGA parts, which is really impressive. There have been threads here recently that discussed the technique, articles, and websites.

Richard

Michael,

Even buying used stuff off eBay, getting set up with a hot air station and a preheater will likely cost you $500-1000.

--
James T. White

Years ago I bought a hot-air gun at Home Depot for about $50. I've wondered about putting separate variable controls on the fan and the heating element, along with a few other details such as thermocouple-type sensors and a microcontroller, if it could be used for SMT work/rework. This would make a good Circuit Cellar article - there was just one discussed using a small toaster oven for SMT work.

I have a hard time understanding why these SMT "rework stations" are so expensive.

-----

As an example of what you can buy in the UK - and presumably elsewhere - see

The requirement for back heater is not very demanding - in the past I have used a variable temperature heat gun (as used for heat shrink), and also a domestic oven ...

You may well get away with a kludged solution - you have to balance possible damage to devices and board against spending money on tools that you will almost certainly use again.

The trend towards SMD and things like BGA seems inexorable - and, if you want to play that game, you need the tools !

Dave

Maybe too expensive. I do not know the brand. If it is industrial equipment to begin with, it will last forever, so used is fine.

A real, physical, auction site is a better place to buy used equipment, if the price is important and one has the time.

The problem with internet auctions like eBay is that it is easy to manipulate the bid by having friend bidding up to your target price. If friend should overreach and end up winning the auction, he does not have to buy from you after all because that part is a private agreement.

At a physical auction, friend (or you) would end up having to pay for the goods, a percentage for the auction house and sales tax on the lot. That makes the crowd more honest - (although it happens that someone will place an opening bid on ones own stuff to push the price a bit higher, risking a

25% loss of course in buying the stuff back. That is a good way to dispose of PC's for. ex).

The people buying there are professionals that will not pay more that maybe

15-20% of what they can sell for (unless they already have a buyer) because they know the odds are that a large part of the purchases turns out to be s**te, that will have to be disposed off. So you, as a one-off-buyer get a better price.