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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.

marakesh
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4 Answers4

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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.

David Schwartz
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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

Journeyman Geek
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This answer is only applicable for soldering and desoldering PTH components used in modern multilayer(4-12) PCB.

Laptop and desktop motherboard manufacturers are continuing use of Lead Free Solder(LFS) for last 5-6 years. This kind of solders' melting point starts at 217 degree Centigrade(C). There are different kind of alloy composition used in manufacturing LFS, whose melting point differs. But only 217C - 227C LFS alloy used in motherboard manufacturing because of its lowest melting point in its class.

Now, it is not the matter of the solder used in your motherboard is leaded (63/37 at 183C) or lead free. If you use a traditional soldering iron / station, you will not be able to melt the solder on the power jack of a motherboard. Only because the motherboard is multilayer and has a wide ground / positive supply copper plate. This wider plate absorbs the energy from your soldering iron, and drops the tip temperature (drop may be between 70C - 100C than your set temp) within seconds. For tradition soldering station even with microprocessor controlled, it is near about impossible to rise and maintain the temperature immediately, because of the heater and sensor accuracy.

The watt and the temperature mentioned in your soldering station will not help in this matter. Rising the temperature will probably damage the solder pad on the board and will not melt the solder on the other side of the board.

To work on modern motherboard, it is necessary to have latest soldering station from any reputed brand, whose temperature rises to 350C within 5 seconds and minimum temperature drop (30C - 50C). Always set your soldering station temperature minimum (solder melting temp + 70C) and increase if required as per application. Using of proper size iron TIP is necessary. Before soldering motherboard it is necessary to clean the iron tip with a damped sponge(made with cellulose) and brass wool / inox wool.

Before desoldering the PTH components, it is necessary to clean the terminals with isopropyl alcohol. After this process, add some new solder to the terminals of the component to be desoldered.

user
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Biswarup Sain
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I've been dumping flux on it

Once the joint is clean, "dumping" more flux on it won't help 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)?

sawdust
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