good, inexpensive hot air station?

Hi - I'm thinking about buying a hot air station. A couple years back I
spent a good deal of time investigating soldering irons and eventually
settled on the Hakko 936 as it was fairly inexpensive (just under $100)
and had the feature set of many much more expensive irons. Now - I'm
hoping to find a similar hot air station. I've been looking at some of
the Hakko units and they're all terribly expensive - cheapest I've seen
so far was about $700 new. Ouch. There are some Chinese Hakko knock-off
brands that sell similar looking stations for a fraction of the cost
hopefully this link works:

http://stores.ebay.com/Madell-Technology_REWORK-STATIONS_W0QQcolZ4QQdirZ1QQftidZ2QQtZkm

But well, I don't like supporting companies that rip off other
company's designs, and I highly doubt that they're made with the same
quality that Hakko's products are made with.

I have seen some used Hakko hot air stations on Ebay for about $350 or
so. Is this something that would be bad to buy used? Do any other
companies make hot air stations worth looking at?

Lastly I should mention who I am and my interest in such a station. I
am a third year EE at UIUC. I've recently started working on boards
that use incredibly tiny chips - the smallest being some DFNs and QFNs
(leadless .5mm pitch chips - awful little buggers). Though I'm quite
good with my iron, I think those may be maxing out my capabilities, so
I think it's time to probabaly look at a more serious soldering
solution.

Thanks for your help,

Michael J. Noone

 

Try one of the Faux affiliates.

It was too good a setup

 

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

 

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.
http://www.zeph.com/pencil.html

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.
http://www.zeph.com/airbathseries.htm
If you can find one used to meet your budget, highly recommended.

Richard

 

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

 

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.

 

Michael,

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

 

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

 

As an example of what you can buy in the UK - and presumably elsewhere - see
http://shop.jabsplace.co.uk/index.php?main_page=index&cPath=5&zenid=70d24716efac53a5784a8cb0d78a7986

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
shite, that will have to be disposed off. So you, as a one-off-buyer get a
better price.