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Solder blobs are not always solder joints ...

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Paul Joppa:
This is just another take on solder joint repair. Something I saw today made me think it was time to say it again.  :^)

Adding solder is not the same as "reflowing" - if the solder joint is bad, it is likely because not ALL the metal involved was heated above the melting point of the solder. Adding solder to the blob does not make the terminal and the wire hotter; usually the iron itself must conduct heat to the terminal and the wires.

The best repair to a bad solder joint is to remove as much of the old solder as possible - you can get a solder-sucker, or use the woven copper tape with flux which wicks it away. Then, when you can see the metal parts, put the iron onto them for a bit before adding solder. Touch the solder to the terminal and/or the wire, not the soldering iron, so you are sure the metal parts are hot enough. When you see it flow onto the parts, then you can take the iron away. One reason this is best it that the flux inside the solder wire will be in the right proportion. The flux that was with the original solder blob has evaporated already, and the excess solder just dilutes the flux in the added solder.

debk:
Paul

Good post. 

When I repair kits made by others, poor soldering is usually the problem.

Debra

Doc B.:

--- Quote from: ramicio on January 09, 2012, 02:29:28 AM ---It's funny to see people who can't solder try to solder.  To a solderer, it seems unimaginable to not be able to do so, and to me, watching an adult do it who can't, just makes them look like a toddler trying to do it.  I thought reflowing was a specific type of soldering for SMD components using paste.

--- End quote ---

Reflowing is indeed a method for SMD attachment. It's also what we call reheating any existing solder joint to the liquid state in order to get it to properly distribute itself through the joint, which is of course exactly what is being done with SMD reflow. It's also called rewetting.

If you think watching a person who doesn't know how to solder is funny, you should watch me try to ice skate. I'll bet there was a time when even you didn't know how to solder.

Grainger49:
I want to note that you need a good mechanical joint first, then cover with solder.  I crimp all my leads onto the terminal strips or tube pins before soldering. 

I get few bad solder joints.  My FP 2 power switch wire fell off after 11 years.  The power switch has no hole in it so it was "chewing gummed" onto the switch with solder.  It failed.

I should have drilled a hole.  I had the same failure in the Paramount I built, the power switch let go of the wire and solder.

elcraigo:
I only try to ice skate if I need a broken ankle.
You should see me solder a BGA with those x-ray glasses I got from the back on the comic book.
I almost always burn myself, probably not enough flux.

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