Desoldering chips with fire

chips

Salvaging components is a staple of any electronic enthusiast, but many times those interesting chips – old 8-bit microcontrollers, memories, and CPUs found in everything from game consoles to old computers – are rather difficult to remove from a board. [Ryan] over on Instructables has a rather interesting method of removing old SMD packages using nothing more than a little fire and a pair of tweezers.

Obviously the best way to go about salvaging SMD components is with a heat gun, but lacking the requisite equipment, [Ryan] managed to remove a few SMD chips using rubbing alcohol as a heat source. In a properly controlled environment, [Ryan] filled a small metal dish with alcohol, set it on fire, and used the heat generated to remove a few components. Alcohol lamps are a common bench tool in a range of repair disciplines because the fuel is cheap and burns relatively cleanly (not leaving an unwanted residue on the thing you’re heating).

It’s an interesting kludge, and given [Ryan]‘s display of desoldered components, we’re going to call it a success. It might also work for through-hole components, allowing for easy removal of old SRAM, ROM, and other awesome chips.

Comments

  1. andres says:

    i use a small butane torch for quickly salvaging components. if you’re not careful it burns the fiberglass though which is not fun to breathe. alcohol seems like a nicer choice.

    • zuul says:

      i was gonna say this, it works pretty well, and hold the part and pull it out with pliers

      • pcf11 says:

        When I’m really stripping boards I use a pick tool like an awl. I just get it under the part, then lever it up. Stab, flick, stab, flick. I’m like Norman Bates! I should get the Psycho soundtrack to listen to while I’m stripping boards. Zing!, Zing! — Zing!, Zing! Although I do have an angled pair of needle nosed pliers that gets a lot of use stripping boards too. I use it a lot like the awl, but with a grab after the stab.

    • defaultex says:

      That’s what I’ve been doing. Using a small butane torch lighter. More often than not it ruins the board but the chips survive as long as you work your way inward from the edge of the board.

    • Tomasito says:

      I also use a small butane torch, sometimes it takes one or two seconds with small components. It’s very handy when you have to desolder something big or something with a big ground plane. The board gets ruined most times, but I think the component survive ratio is better than with a hot air gun, because it’s much faster and the heat is more concentrated.

  2. RandyKC says:

    It’s an easy way to get the chips off the board. But what is the recovery rate? Putting the heat on the whole board will fry most of them, won’t it?

    • F says:

      you’d be surprised

      chips are made of plastic and rock (silicon).

      if the plastic is not damaged by heat then the rock inside is probably intact too.

      The stuff you read in chip spec sheets about maximum soldering temperatures are worst case scenarios for the production line where 0.01% failure is a disaster.

      • Trui says:

        Silicon is not a rock, it’s a metalloid. You’re probably thinking of silicon oxide. But heat damage most likely occurs not in the silicon die, but on the contact area between the gold bond wire and the aluminum pad. The two metals can form an intermetallic compound that’s brittle and a poor electric conductor. The formation of such compounds are sped up dramatically with a rise in temperature. Look up “purple plague”.

  3. orb says:

    Reminds me of Agbogbloshie

  4. wolfy02 says:

    I’ve done the torch method, burned a few boards in my time too. After getting burned one too many times, i picked up an old flat-iron grill from Goodwill for $2. Works great! gets super hot, not hot enough to burst into flames, but hot enough to melt solder and keep it molten. Stores great too! I’ve picked boards clean with it before. Would definitely recommend this way to anyone looking to salvage massive amounts of parts from a junkbox.

  5. renaissanceman says:

    Back in the old days of CRT TV’s, I used to “desolder” interesting components of broken TV’s by heating up the PCB on the back side with a blowtorch. When the solder was molten all it took was 2 or 3 blows with a hammer to get the components off. I’m still using some of the parts I saved.

    • Nate B says:

      “By all means, do not use a hammer.” ~ IBM maintenance manual, 1925

      That’s hilarious. I recall seeing a video some months back, of some hackers who rigged a paint-shaker and a toaster, to heat the solder and shake the components off the board. Anyone able to find this again?

      • pcf11 says:

        Based on my experience with heat it and beat it component salvage I can see their paint shaker rig having the same problems as not removing parts between slaps. If you don’t then parts you’ve removed earlier tend to get solder splattered by subsequent slappings. At the very least you have to clean parts with a soldering iron, which is tedious to say the least, or in the case of some parts you trash them. Like electrolytic capacitors with plastic sleeves on them. The molten solder ends up melting that plastic off the capacitors. You don’t want your cans naked do you?

  6. Someone says:

    What about the heat gun ? No one else use it here ?

  7. Humble reader says:

    Electrolytic caps roasting on an open fire, Jack Frost nipping…

  8. John U says:

    Ah, I see we’re back to “It’s not retarded, it’s hacky!” on HaD.

  9. Blue says:

    During a terrible “reflow” attempt I was able to remove 90% of components from a motherboard using an oven.

  10. Fallen says:

    If you don’t want to damage the PCB, I would recommend chipquik. That stuff is fantastic. It melts at something like 55 degrees Celcius, I’ve never lifted a pad while using it!

    But if you’re just harvesting components I guess the fire method works.

    • pcf11 says:

      When I’m stripping a board for parts I’m not too concerned about lifting a pad. When I do rework I use a different mindset, and methods than when I salvage too. I call it prioritizing.

  11. nelsontb says:

    Suspend the board a few cm from an electric oven and slowly ramp the temperature to 100ºC -150ªc, to let the board heat up evenly, then hit the component with a hot air gun and lift the component

  12. pcf11 says:

    I think I’ll stick with my solder pot for salvaging electronics.

    http://i.imgur.com/2LqkdOi.jpg

    Fight solder with solder. It is better than any heat source alone.

  13. Hirudinea says:

    FIRE GOOD!

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