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My laptop has had a wobbly DC power jack and intermittent issues making a connection and charging for nearly a year. Yesterday I finally decided to bite the bullet and replace the jack. Removing it was tricky, I ended up more or less yanking off a couple of pins. With it off, I've discovered that the reason it was so tricky was that the solder is absolutely impervious to anything I do. I've been dumping flux on it and blasting away with heatgun and soldering iron, trying to melt it and get out the remnants of the pins, but nothing works. I'm not the best solderer in the world, but I've never heard of anything like this.

What's going on here? Am I approaching this completely wrong? Any suggestions would be appreciated, I'm out of ideas.

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3 Answers

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My bet is the solder just requires a higher temperature than your soldering iron is able to achieve. My second theory would be that your iron is hot enough, but still can't manage to couple enough heat into the component to get the solder melted. My third guess would be that you're trying to melt something that's not solder but actually part of a piece that has broken and you should be applying heat elsewhere.

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It could be that the joint is covered in some particularly strong conformal coating that is actually solder-proof. Some time ago, I was trying to unsolder wires form a computer microphone and I used 80 W soldering iron at 400 C for maybe 30 minutes on the joint and I still couldn't remove the solder. I tried sanding the stuff away, but I couldn't even scratch it. I think that they ought to paint tanks with that stuff. :) – AndrejaKo Jan 14 at 1:03
A laptop of any recent vintage will have been manufactured with lead-free solder (it's been the standard for a number of years now). If your iron isn't specifically rated for lead-free, it's probably just not getting hot enough. You probably need to invest in a new iron. – Michael Kohne Jan 14 at 1:05
@Michael Kohne From where did you get the idea that some special irons are needed for lead-free soldering? – AndrejaKo Jan 14 at 2:28
Common lead 60/40 solder melts at 190C. Some lead-free, high-strength solders require as much as 485C to melt. Though I'd be quite surprised to find anything requiring over 300C on a part made with so much plastic. (The ultra-high-temp solders are usually used only on ceramic substrates.) – David Schwartz Jan 14 at 2:40
@AndrejaKo - Lead-free solders melt at higher temps than leaded solders. Older single-temp irons were calibrated for a proper melting point for standard leaded solder, and won't touch the lead-free stuff. Further, older variable temp soldering stations don't always go up high enough to deal effectively with lead-free solder. – Michael Kohne Jan 14 at 2:47
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up vote 1 down vote

I've been dumping flux on it

Flux won't help for a desoldering job.

Am I approaching this completely wrong?

Maybe. The old joint probably uses unleaded solder, which can be more difficult to work with.

What kind of "solder iron" are you using? Perhaps the iron should be taken apart and cleaned; make sure the tip has a good (clean and solid mechanical) connection to the heating element.

Is the tip properly "tinned"? Proper preparation of the iron's tip is crucial for heat transfer from tip to joint.

Do you know how to "wet" the old joint with fresh solder? Adding new solder to mix with the old solder often helps the old solder to flow.

What are you using to remove the old solder (sucker or wick)?

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Flux won't help for a desoldering job.[citation needed] – AndrejaKo Jan 14 at 0:26
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"A piece of desoldering equipment was sold to a company. A couple weeks later they brought in a board because the operator was having trouble removing solder from a row of connectors. Using the purchased piece of equipment, a connector was quickly removed by an experienced technician. When the board was taken back to the company by the salesperson, repair people were told to "clean and flux" first. The area where the operator had been trying to desolder proved why the job was not successful: it was extremely dirty. The problem was resolved." - N9ZIA – David Schwartz Jan 14 at 0:34
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up vote 1 down vote

The trick i found for higher temperature solder is... more solder. Melt your own solder into the current solder, remove it with a braid. Rinse and repeat until you remove all of the old solder.

It isn't just that its lead free, but most mass produced things use wave soldering rather than normal solder

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