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So, SD Card connector on my raspberry pi broke down and can't hold the card well enough, so I'd like to solder a new card connector. While I'm at it, I'd also like to remove RCA and audio connectors, as I'm 100% sure I won't ever need these.

So, armed with solder wick and my soldering station, I'm trying to de-solder these elements. But, for some reason, the solder used in rpi won't flow to the wick. Adding more solder to the point and then using the wick only removes the freshly added solder, but the element is still soldered to the board.

So, for those who successfully managed to desolder anything off raspberry, how did you do that? What temperature did you set your soldering iron at? What methods, what dark magics did you apply? Or did you use hot air, and if, at what temperature?

  • Perhaps adding lead-free solder could help. I had some motherboards recently that I just couldn't desolder. Adding some lead-fee solder (that is the only solder I have) helped a little, but it was still a pain in the you-know-what. – Gerben Aug 21 '13 at 19:31
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It's probably lead-free solder which has a higher melting point (~220°C) than lead solder (~180°C). When you add lead solder to lead free solder, the lead solder melts and acts as a heat sink preventing the lead free from melting.

Additionally, the boards would have been cleaned after production so there would be no flux. Flux aids in the re-flow of solder to components by preventing the oxidation at high temperatures that stops the metals binding.

Finally, the board may have a coating spray or painted on to prevent corrosion. This can gum up the tip of your iron making it less effective.

So to remove the part, clean the area with isopropyl alcohol to remove the coating (if it has one). Add flux to the pins to be de-soldered (can be purchased in a bottle from electronics stores). Turn your iron temperature up a bit to compensate for the difference temperature. Have patience.

  • 2
    Flux doesn't lower the melting point of solder – John La Rooy Aug 22 '13 at 2:00
  • @gnibbler You're right. It was a throw away comment from the point being that there wouldn't be any there. Corrected. Thanks :) – SLaG Aug 22 '13 at 2:37
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Leaded solder and unleaded solder don't really like to mix. You can try a few iterations of adding leaded solder/wicking it off, but make sure you've got enough temperature to melt the lead free solder.

Pulling the parts off with hot air is probably easiest. It would be better if you had a preheater for the PCB, but if you are patient, hot air can probably do the job.

Mask off the area with kapton or Al-foil so you don't cook surrounding components too much. Practise with the hot air on some old motherboards or similar - the ground/power planes take a long time to warm up. Expect at least 3-5 minutes of hot air to slowly heat the board/part to avoid thermal shock.

1

I'd recommend you look at chip quick. It is a solder paste which lowers the melting point of solder which gives you more time to do your thing with the solder wick. I also highly recommend a solder sucker.

Joe Grand illustrates how to use chip quick in his very long and low quality video here: (skip to about 10 minutes in)

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