Hand soldering tiny QFN packages. How do you do it?

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Some boards I'm building have tiny 16-pad 3mm x 3mm QFNs which I am hand soldering.

I've found a method that works for me:

Use tacky flux and build up some solder on the PCB pads, taking care not to get too much on the centre pad.

The use a hot air gun to heat the component and board together and tweezers to drop the QFN onto the molten solder pads. 

The flux ensures no solder bridges.

 

It works well for me, but I was just wondering what other methods you use?

 

SpiderKenny
@spiderelectron
www.spider-e.com

 

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I find the qfn 'swims' so you need to hold it in position. I did hope the solder tension would pull it into place. I needed to touch up a few pads with the soldering iron with a narrow tip. Hint: design the pcb with pads that extend beyond the package so you can solder easier.

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Kartman wrote:
design the pcb with pads that extend beyond the package so you can solder easier.
 

That's exactly what I did. :-)

SpiderKenny
@spiderelectron
www.spider-e.com

 

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Video: "How to Solder QFN MLF chips Using Hot Air" (Link)

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I've never successfully soldered one of those. Next time I'll try extending the pads so they reach a ways from the chip.

 

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Thanks Chuck - I'll have to have a look at that and give it a go.

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I use a toaster oven if I have too many hard SMDs to deal with.

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indeed if you can extend the pads, but else you put a bit of tin on the PCB and a bit of tin on the chip, then apply flux to both the pcb and the chip and place it.

then you can use hot air to slowly heat the board end chip and you should see it 'sinc' onto the pads.