DogEars
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Washing after soldering, is water OK?

Sat Oct 13, 2012 6:02 pm

I'm using water soluble flux so after soldering I should wash the board with water, it feels very odd to do such a thing is it okay to do so?
Cheers,
Ears.

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fos
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Re: Washing after soldering, is water OK?

Sat Oct 13, 2012 6:17 pm

Ears,

I would suggest using a thin rosin core flux solder. You will get much better long term results. Water soluble flux is designed for industrial use and the cleaning methods they have available. For hobby use, water soluble flux will give imperfect solder joints over the long term with no positive reason for using water soluble flux in the first place.

Jeff
https://faroutscience.com

DogEars
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Re: Washing after soldering, is water OK?

Sat Oct 13, 2012 7:26 pm

I'm new to soldering and I'm a bit daunted by the whole surface-mount thing, googling around I've seen a few mentions of using 2331-zx flux to make life easier, but they all mention washing it after with warm water.
But you think it's a bad idea?
Cheers, Ears.

repton
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Re: Washing after soldering, is water OK?

Sat Oct 13, 2012 8:42 pm

I've always just used normal flux cored lead based solder and find it works fine without any extra flux even on surface mount stuff.

Paul
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mahjongg
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Re: Washing after soldering, is water OK?

Sat Oct 13, 2012 8:44 pm

As long as its distilled water, and you give it long enough to dry before powering the board I don't think it should be a problem, but it depends a bit on the kinds of components that are on the boards.
For example emersing any batteries in water isn't a good idea, also non encapsulated transformers and such.

Also, it might be that the industrial cleaning methods use some kind of ultrasonic vibration method to clean, and the water is just a medium, so without the ultrasonic vibration it doesn't actually do anything.

DogEars
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Re: Washing after soldering, is water OK?

Sat Oct 13, 2012 9:27 pm

mahjongg wrote:it depends a bit on the kinds of components that are on the boards.
What about the RPi specifically, I was concerned about the BGA Soc.
What do you think?

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Burngate
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Re: Washing after soldering, is water OK?

Sun Oct 14, 2012 10:18 am

Water soluble flux was invented (and is used) as an eco-friendly alternative to some nasty solvents previously used - similar to the paints used in automotive manufacturing.

Distilled water - or deionised water - is pretty much an insulator, until crud gets desolved in it, so the crud must be washed away properly.

Under the SoC, and under the RAM, water can remain for a very long time - there's not much air-flow there to remove the water vapour.
So getting it properly dry will be difficult.

Rosin flux solidifies to an inflexible solid, which may perhaps cause problems, and so best practice is to remove it. I've never had a problem, but you never know ...

You can get non-rosin-based fluxes that are flexible and so don't cause that problem, so don't need to be removed. They also don't give off noxious fumes when hot. I also prefer the smell of it, though others differ

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mahjongg
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Re: Washing after soldering, is water OK?

Sun Oct 14, 2012 12:07 pm

I have nothing to add to the above.

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fos
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Re: Washing after soldering, is water OK?

Sun Oct 14, 2012 4:50 pm

With any type of solder, you should use the minimal amount of solder necessary to seal the joint. Solder should never be used to secure the joint. Using the minimal amount of solder will also minimize the amount of flux leaving a clean joint. I have boards that are still functional after decades.

An old ham radio qrp builder..

72, de Jeff WD4ET

PS. I'm still using an old 5 lb. spool of Ersin Multicore solder. It was the best.
https://faroutscience.com

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Burngate
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Re: Washing after soldering, is water OK?

Sun Oct 14, 2012 4:58 pm

500 grams 22 SWG Xersin 2000 (Multicore Solders Ltd) 852/466

DogEars
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Re: Washing after soldering, is water OK?

Mon Oct 15, 2012 2:46 pm

Does anyone know how the water is removed from the CPU & RAM during the manufacturing of the RPi?

If they heat them up to drive it off what temps are acceptable?

Cheers,
Ears.

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gordon@drogon.net
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Re: Washing after soldering, is water OK?

Mon Oct 15, 2012 4:10 pm

fos wrote:With any type of solder, you should use the minimal amount of solder necessary to seal the joint. Solder should never be used to secure the joint. Using the minimal amount of solder will also minimize the amount of flux leaving a clean joint. I have boards that are still functional after decades.

An old ham radio qrp builder..

72, de Jeff WD4ET

PS. I'm still using an old 5 lb. spool of Ersin Multicore solder. It was the best.
I'm still on the spool or Ersin multicore I got 25+ years ago, although I had to admit in those intervening 25 years - until I started building stuff again some 5-6 years ago it had lain mostly unused...

Can't get 1:1:1 trike anymore - probably for the best though - I find the current PCB spray cleaners nowhere near as good - however I might pop a PCB or 2 into the little ultrasonic cleaner bath I have to see what it does to them after a spray with the latest Maplin cleaner I'm trying ... Stick the boards in the bottom of the range to dry out afterwards will probably be ok!

-Gordon
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Gordons projects: https://projects.drogon.net/

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