Hand soldering SO8 with GND paddle

Dec 30, 2009 5 Replies
A

Any tips on ways to hand solder SO8 packages which have a GND pad underneath? I'm doing a PCB layout for a hobby project using one of these devices so I could for example put a large plated through via under the device big enough to get my soldering iron tip into. Is that a bad idea?



The device is a high-speed prescaler which dissipates ~ 350mW. The GND pad not only needs to be well grounded for RF but also needs a low thermal resistance to remove all that heat.



My board is standard 2-layer FR4 with an almost continuous ground plane on the bottom.



TIA


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A

Nope, it's pretty standard.

Should be OK, I guess you need a good iron that can bring a lot of heat to the area quickly.

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N

You better put 5 or 6 32 mil / 0.8mm vias underneath it. If you pour solder in on or two vias it will come up through the other vias.

Failure does not prove something is impossible, failure simply indicates you are not using the right tools... nico@nctdevpuntnl (punt=.) --------------------------------------------------------------
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J

Sounds good to me for a hobby project - I did this for a QFN and it worked fine.

John Devereux
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Q

Large via under the thermal pad works.

You can also solder this in a toaster oven or waffle iron with the flat plates. Tin both the thermal pad and PCB pad. The solder bumps should touch, but don't make the bumps too big or the part will float. Coat with a little flux and bake.

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L

hese

ea?

D pad

on

That's what I use for prototypes. Soldering is easy with my Metcal system because of the phenomenal heating capability.

Leon

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