Desoldering through-hole chips

GuntzGuntz
in The Brewery
Regular old soldering is no problem for me... But desoldering is another matter entirely. I can never seem to fully or properly desolder any kind of DIP IC, unless it's like a DIP12. Basically, I want to be directed at the right kind of equipment I should have, like a proper desoldering station.



But more than that, can somebody direct me to where I can learn to desolder properly? Like what temperature do you set the iron to? How long do you hold the iron on the pin? Is flux needed for a clean desolder? How do you prevent pins from sticking to the vias (solder rings).

Comments

  • removed04092017removed04092017
    I just follow some simple steps for desoldering mask ROMS from lets say NROM games:



    1. Apply a little flux to each pin down the row.

    2. Put heat on it, wait until you see it all change a different color to show it melted.

    3. Suck it up.



    But the thing is I only do that for the normal pins, the through holes I clip and just heat up and pull out as I seem to never be able to fully desolder them from both sides no matter how long I let it heat up.
  • rokubungirokubungi
    I always try to keep a brand new desoldering iron tip around because nes double sided boards seem to use a fairly hard to desolder solder that only a fairly new tip will desolder cleanly. If the solder doesn't come up in one go you may need to add some new solder so there's enough for the nozzle to 'grab' I would like to get a vaccine desoldering station sometime soon because those bulb type will make my hands pretty sore after 112+ joints any suggestions on a good but inexpensive one?
  • GuntzGuntz
    Thanks for the suggestions guys. So I'm not the only one who absolutely hates trying to actually desolder ICs out of NES boards? All I was hoping to do was save chips from better games, like Super Mario Bros. 2.... That is if I can ever get this one corroded TS-ROM-01 board to work reliably. eBay can go to hell...



    I had a look around and I thought this desoldering station looked pretty decent.



    http://www.ebay.ca/itm/SMD-Hot-Air-Gun-Iron-Desolder-Soldering-Rework-Station-Brushless-Ball-ESD-BGA-/370592391281?pt=LH_DefaultDomain_0&hash=item5649072071
  • Kosmic StarDustKosmic StarDust
    Don't butcher Super Mario Bros 2 & 3 carts. I'm sure there are some "sucky game" donor boards out there that can be used instead.



    I've always struggled with desoldering. I ususally start with a solder braid to suck up as much metal as I can. Then I pull gently on the back side of the component with a pair of pliers, while heating the leads with the soldering iron. Then I wiggle the component loose while heating alternate leads. At least it works for two or three lead components like capacitors, resistors, transistors and stuff, but with an IC, you're kind of stuck between a rock and a hard place.



    Industrially, for surface mount components the entire board is heated until the solder flows, then components are added. For through hole chips, maybe you could use a heat gun (like a tiny blow drier but many times hotter) to heat the entire area on the backside of the board around the IC, until all the solder flows, then lift the entire IC out of the board with pliers. I've never used a heat gun, but it would likely work.
  • rokubungirokubungi
    For surface mount I just bought some bismuth chips, just add a bit to most solder and the melting point gets low enough that it will stay liquid for a while.. the Mario 2 I'd guess he's using for FF3 if it's the full pin one. Solder braid I've found to be near useless for hole through, but a necessity for surface mount soldering
  • Game-Tech-USGame-Tech-US
    I recently found a super easy way to get DIP chips out.

    I use a cheap weller soldering iron with a 4mm (IIRC) chisel tip <- important, trust.

    When desoldering I turn it all the way up.

    My solder sucker is the cheapest POS you can import on ebay, like $3, you can see it in a bunch of my youtube vids.

    Watch this one @ 2:00 minutes, that's exactly how I do all DIP chips.

    It's super easy and quite fast and not too hard on the hands and fingers once you get used to it.

    Just don't yank 'em out till you're sure the pins move freely, I use the soldering iron to make sure they are free and they usually either move freely right away or 'click' off that last little bit of solder and then are free.

    If it still needs coaxing i'll add more solder and try it again.

    Watch out for the power and grounded pins, they usually aren't themal pads and require more heating time to melt the solder, but you'll see it happen or if you have enough force on the iron the pin will move.

    Also, you're not likely to encounter lead free solder on any NES stuff but if you do add some leaded to the mix, it will help greatly when working with it!
  • Game-Tech-USGame-Tech-US
    BTW those power and grounded pins are the reason hot air can ruin a board, it takes too much time to melt them and by that time the board has warped badly and if you're unlucky like me, a whole quarter sized area will lift and possibly explode in to your eye balls! Yeah it happened!

    Too bad I wasn't recording at the time, epic 'oh shit' throw stuff and run away reaction!!

    And you will start burning and lifting traces etc and you don't want that.

    So, to get around that I started sucking the solder out of those pins before I used the hot air, worked better and faster. But to instal a socket or eprom I was drilling out each via because using hot air to do it is even harder!

  • Taco!Taco!
    Oh god why do you guys torture yourselves and use those old school solder pumps? Just buy a desoldering gun, like $20 for one from Radio Shack with a temp control. That's all you need, I change the tip on it about once a month or so. No flux or anything. I used to have all sorts of issues with double sided solder pcbs' until I got that. For real, look into it, it makes a WORLD of difference.
  • GuntzGuntz
    I've tried both the plain pumps and the powered desoldering variety. Even a good working 30w iron doesn't seem to make the solder on the cartridge boards melt any easier. I think the biggest issue is the pump I have in this iron right now, it's terrible. It doesn't snap like a good one, the suction is marginal at best...



    Concerning SMB2, it's the only NES game that used the early TSROM version with all the pins. It's for making a FF3 cart.



    So I guess the part I need to be most careful about is making sure the pins are actually free, or can easily snap off the solder rings (via). I keep thinking I can just snap the chip out, but even just one pin still firmly stuck ruins the whole procedure...

  • removed04092017removed04092017
    Hence the reason you take care the the pins that aren't soldered to both side, then just heat them and pull them out. Trust me, best way to do it. As long as you don't plan on using the Mask ROMS again.
  • marvelus10marvelus10
    I use one of these with very few problems, make sure you ask for some extra tips because you will go through them quickly.

    http://www.ebay.com/itm/40W-Auto-One-Hand-Desoldering-Iron-Tool-Spare-Tip-NEW-/140774119971?pt=BI_Welding_Supplies&hash=item20c6ca9a23#ht_523wt_1270
  • sevansevan
    Desoldering is always an issue for me as well. One time I nearly burnt my PCB trying to desolder a transistor. You could see a black spot on the green PCB. I was trying to make the hole and surroundings clear of solder but I wasn't able to clear them all completely. This happens almost everytime I try to desolder a part from PCB. I think a person needs to have knowledge on desoldering before soldering anything.



    pcb assembly
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