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I need to get a heat gun so I can do some SMT work. What wattage / heat range should I be looking for?

Obviously it needs to get hot enough to melt the solder (preferably lead-free) yet not fry the components. I have seen everything from about 1400W up to 3400W with max temperature ranges anywhere from 350 to 650°C

So what wattage / max temperature do I want?

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  • \$\begingroup\$ I haven't used heat guns yet for soldering, but 3.4kW(!) sounds like a lot. I'm doing SMT with a 30W soldering iron. Did you say 'fry'? \$\endgroup\$ – stevenvh Jun 24 '11 at 8:57
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    \$\begingroup\$ I undo SMT with a 30W soldering iron. The thing with solering irons are they are direct heat transfer, so they need less wattage to get the heat to the solder. Heat guns need a lot of power to heat the air to stupid levels while blowing it through. \$\endgroup\$ – Majenko Jun 24 '11 at 9:03
  • \$\begingroup\$ Last time I used one was in college back in the late '80s. \$\endgroup\$ – Majenko Jun 24 '11 at 9:05
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    \$\begingroup\$ @Matt Jenkins no need to put stuff in big letters like that. It is a proper question and putting a title like that just makes the question look trashy \$\endgroup\$ – Kellenjb Jun 24 '11 at 14:07
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    \$\begingroup\$ I'm used to SU where if something even remotely smells like a shopping request it gets instantly slated regardless. \$\endgroup\$ – Majenko Jun 24 '11 at 14:09
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What you are asking for is specific to soldering. It's not called a "heat gun", but a "hot air soldering station".

At a minimum, it must have a way to set the output air temperature over the normal soldering range. This should be calibrated somehow, like a degF or degC reading, not just a warm/hot dial. Having air flow rate control is also very useful, and I think most hot air stations have that. Otherwise, I wouldn't worry about power too much. That's its business, as long as it can maintain temperature at whatever flow rate you set. I just looked at the back plate on ours, and it says 270W and has a 5A fuse.

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I do extensive SMD work/rework using a Weller WMD 1A station using a hot air pencil among other things.

You need a temperature control of 300-500 degrees celcius, it depends a bit on what you are going to solder. Power is not the primary selector here.

Airflow is more tricky as, like barsmonster wrote, the crucial thing here is that you do NOT want the airspeed velocity to blow away your parts. Thus, the flow per minute is not enough by itself, you need the nozzle diameter of the hot air tool. For the Weller I use, it is about 6 mm wide and you can set the airflow between 1-10 L/min - I usually never go below 50% but at that flow, 100% will blow away stuff.

The 150 l/min you quote seems far out crazy, that sounds like a blowdryer :) Or was that in some kind of US units?

Note that in practice it is not useful to use hot air for reworking small SMT components. A soldering tweezer is much more useful here (or even a normal soldering pencil with an SMD tip). You need the hot air for desoldering chips, and for soldering chips with a ground pad.

You also NEED a microscope or benchmounted magnifying lens, but I'm sure you know this :)

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Power is not as important as temperature control.

You need it to be able to stabilize air temperature at 250-300-350C. Power might be from 200W and up, as long as it is temperature controlled.

Also ability to control air speed is nice (too much air will blow stuff away).

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  • \$\begingroup\$ I have found one that's controllable between 60 and 600°C, with 200 or 550l/min air flow. It's also the cheapest one listed ;) Does that sound about right? \$\endgroup\$ – Majenko Jun 24 '11 at 9:25
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    \$\begingroup\$ minimal air flow is way too high, but should be ok for heavy repairs (defenitely will blow away 1206 things). \$\endgroup\$ – BarsMonster Jun 24 '11 at 9:39
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    \$\begingroup\$ Look for something like AOYUE 968 or similar hot air rework stations :-) \$\endgroup\$ – BarsMonster Jun 24 '11 at 10:13
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    \$\begingroup\$ Well, 100$ is more than adequate for a great tool which will serve you for the nearest 20 years :-) Also, your productivity would be twice higher than with generic hot air gun, due to all these interchangeable nozzles & fine controls. \$\endgroup\$ – BarsMonster Jun 24 '11 at 11:07
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    \$\begingroup\$ 100$??? Where from? get me one! The ones I found range from £300 up to £1000... \$\endgroup\$ – Majenko Jun 24 '11 at 11:08

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