desoldering a power pad IC

All my talented production people are gone for the day, and I need to remove a TI TPS26600 E-fuse part from a board [1]

It's an MSOP16 powerpad, so I have to desolder the pad underneath after I desolder/destroy all the leads.

My innovation is to put a glob of Dow 340 silicone grease on top, then lay a big high-temp Metcal tip on that. Pry gently and wait for the power-pad solder to melt.

A little pre-heating with a heat gun would help for a really agressively heat-sunk part.

[1] The e-fuse has a tendency to blow up. Not a good idea.
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John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  
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John Larkin
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Wear eye protection ;)

You could probably just use the heat gun alone to get the part off.

Cheers

Reply to
Martin Riddle

I'd desolder everything in sight and probably melt a couple of connector shells. The folks downstairs have better tools.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics
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John Larkin

Go downstairs and use their tools.

Reply to
John S

I got a cheapo hot air machine, $50, next day, literally in stock at the Amazon warehouse down the highway. Instantly relieved the frustration of fumbling with 0402s, and the impossibility of working with thermal pads. That is now replaced with the tedious wait of the board heating up, which I can deal with. (It takes a good five minutes, of elevated heat, to get a many-layers-copper-pour board up to soldering temp. Maybe a minute for few-layers, low-copper boards.)

Tim

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Seven Transistor Labs, LLC 
Electrical Engineering Consultation and Contract Design 
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Reply to
Tim Williams

I don't know how, and I might break something. They get upset when I break their stuff. I'm also not allowed to use the good shop tools on FR4.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics
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Reply to
John Larkin

Go to Zeitgeist and drag one of them back.

Hopefully that didn't let off toxic fumes.

My innovation for such jobs was a trudge into the kitchen, getting a snippet of aluminum foil. The thicker high quality kind. Then I take a scalpel and cut a square hole of almost the exact IC outline including pins. I lay that over the IC and tamp it in place with my fingers. Now the heat gun does the job while holding a watchmaker's screwdriver under an IC corner while exerting a very slight turning motion. I can feel when the IC wants to come loose, a coule seconds more and I can lift it off.

One upside is that I do not have to unsolder, cut or grind any pins. This also minimizes the chance of accidentally lifting a pad.

I guess I could have rightfully expensed 10 cents for all the aluminum foil I used so far.

Despite being an electronics engineer I have a hard time trusting anything electronic or any thermal gizmos to provide overcurrent protection. Seen too much grief with that. I prefer a real fuse or an electro-mechanical breaker.

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Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

You should definitely learn to use the hot air re-work station. It's only slightly more complicated than a hot air gun. Bribe them with chocolate... that usually works.

George H.

Reply to
George Herold

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