Looking for a quick way to desolder those pesky DIP chips? Check out this handy little tip in the video after the break. [Clay Cowgill] shows you the easy way to do it.
Normally, before you desolder a Dual In-line Package (DIP) chip, you have a decision to make: Are you interested in saving the chip or the PCB? The repeated cycles of heating and reheating the PCB while using solder wick, or even a “solder sucker”, can cause a real problem for the PCB. You run the risk of delamination of the PCB traces. Some phenolic based PCBs can barely handle one extra heat cycle, while as a top-quality PCB might be fine with 4 or even 6 rework attempts – but we’ve lifted off tracks with less. And all that thermal stress isn’t exactly the best thing for the chip itself. You risk ending up with a dud.
The other trick commonly used is to cut the pins of the DIP and then you can treat each pin as a single through hole part – and that is generally less aggressive to the PCB, there by saving your board, but destroying the chip.
In the video [Clay Cowgill] is using a Hakko 850 hot air rework station to desolder parts from an Atari 130EX motherboard. He’s able to effortlessly remove the chips, and save the PCB, all without applying and re-applying heat over and over again. That’s something we’ve seen before – the interesting part is where he then uses the air flow to blow the through hole openings clean – making for some of the fastest and cleanest DIP removal we’ve ever seen without using a dedicated desoldering gun.
[Thanks [wblock] via Eevblog]
or use low melt/quickchip and zero risk
Once you’re good at it– and depending on the type of board– I think it’s far safer than any of the ‘contact’ methods (desoldering braid, a vacuum desoldering iron, Sold-a-pult, etc.). On old (70’s, 80’s era) PCBs without soldermask and/or boards with thin annular rings and traces it’s really easy to delaminate the metal from FR4 or phenolic with the tip of an iron. If I’m particularly worried about it, I turn on a temperature controlled hot plate under the PCB to make it easier. (I would have done that in the video, but the plastic camera tripod was sitting on said hot plate.) ;-)
low melt is considerably lower temperature than you’d need to damage tracks or components, its easy to clean up too.. it’ll do smd and thru hole. i’d be hard pressed to believe there was a better method beyond some edge case where low melt wasn’t compatible, but YMMV.
lower temperatures seem to me like they’d be always be safer, even if its contact.
desoldering braid is probably the easiest to damage things with, solder suckers work well most of the time, but tou can really mess things up.
YMMV, of course, but in my experience any ‘non-contact’ method with decent process control is preferable to contact. When you’re adding an alloy you still need to get the base metal to its melting point and the tip of a soldering iron makes for a very rapid thermal shift on a pin (and it provides an ESD path if you’re not working at an ESD safe station with a good ground strap, etc.)
The other upside aside from speed and safety is cost– there isn’t any. No alloy metal to buy and a couple pennies of electricity that you’d otherwise use in the iron anyway.
For SMT it’s about as easy as it gets, heat the pads to the reflow point and pick the part off with a tweezer or vacuum pencil. That’s really nice for reusing parts too because there’s essentially no clean-up required and on fine pitch parts (say, 0.5mm TQFP’s or worse) there’s no wicking of the solder up in to the pins.
Low melt is cool and all (pun intended) – but you still have to heat up the original solder.. And IMHO, high heat for shorter amount of time is less stressful on PCB’s then low, long heat. In addition, most solder wick has some really aggressive fluxes in it. And it makes a mess. And it take longer.
you have to melt the solder either way so the “pin” temperature will be the same just for a shorter time, but once its mixed it’ll melt at lower temperatures and you can keep it melted at a much lower temp, i use a preheater to prevent thermal shock to the board and components , the solder won’t harden as quickly so you don’t have to work as quickly, or be as accurate, especially when working with more difficult parts..
i feel like its a comparison of the worst possible on one side, versus the best possible on the other side. you shouldn’t have to keep the heat high for anywhere near long enough to damage anything at all, and low melt is a very low temperature to keep it flowing. i disagree that the lower temperatures for low melt is more damaging than regular solder, especially unleaded is worse , but again YMMV
I use Q-tips and flux to clean off the pads, as is recommended, not solder wick which can cause more problems.
https://www.youtube.com/watch?v=UmD7F0–7Lc
works perfectly, no damage to chips.
Sorry Charlie – yea, but still.
Hi George! Do you have recommendations on starting points for appropriate temperatures and flow rates? Or just a “how to use a hot air reflow gun”?
I thought it was cool :) Neat find and thanks for sharing.
OK, someone need to start working on a hack with a $10 Harbor Freight heat gun to do this.
These hot air tools has temperature control so you don’t burn the chips or PCB. Some of the more expensive heat gun now has temperature control, but they are around the price range of hot air tools from China *BUT* without the wide selections of hot air tips and separate air flow + temperature.
Nonsense. You can pick up a Craftsman heat gun with pretty precise temperature control for pretty cheap.
Or, you *could* just get the *right* tool that’s designed for the job. The Crafstman may let you adjust the temp, but it doesn’t let you control the rate of air, and it doesn’t come with different sized tips to concentrate heat only where you need it.
Makeshift tools are never better than tools designed to do a specific job.
FWIW, a few years ago, I soldered, de-soldered and re-balled countless Xilinx BGAs with a Milwaukee heat gun. At first, because I didn’t have the money for the proper equipment. Then later, it didn’t matter any more cause it works just fine. This is for prototypes; I would not dare sending out production units this way….
Lots of flux. Put the heat gun on high and hold it up high above the chip. Slowly lower it. Watch the magic….
I use a budget heat gun with a small (10mm) nozzle to remove components all the time and I have yet to destroy a device (I have blown some 0603 packages onto the floor, never to be seen again…). There definitely is some skill involved, and I normally use the low setting, but it works a trick.
I have done it plenty without destroying chips or boards. I made a little nozzle for it out of aluminum flashing and good to go. On especially sensitive stuff I would shield with Polyimide tape. I’m not sure of the efficacy of the shielding but I haven’t fubared a part yet.
Plug the heat gun into a heavy duty dimmer so you can throttle it.
I used to have a special DIP desoldering tip for my soldering iron. It took forever to heat up but it made it possible to desolder an entire (300mil) DIP chip in a matter of seconds, by heating up all the pins at once. I used it to save many chips.
One of my problems is telling when the solder is melted. It’s not always obvious when it melts and then I run the problem of either trying to force the part off the board while solder is still hard, or cooking the part because it does not look like the solder is melted.
Sometimes I don’t know if I am having trouble getting the part off because the solder isn’t melted yet or if the part was glued on before soldering. I seem to have a lot of trouble with motherboard capacitors especially.
Visually the surface of the solder will change a bit when melted. Flux can help highlight that. But for most people, just applying a small up force on it with tweezers, the chip will let you know when it’s ready. The part of the process that is a bit of an art is knowing how to evenly heat the chip’s pins with a swirling motion. But that comes with not too much practice.
It’s not the same anymore with lead free solders.
Motherboard capacitors are a combination of intentionally kinked leads (so it doesn’t fall out during soldering), being a through-hole part and the motherboard using much thicker inner copper layers (usually power planes) for both good electrical and heat conductivity.
You need to set the temp much higher and use a beefy tip (more thermal mass) to overcome the superb cooling capability ;-)
Another method is to use a preheating plate under your motherboard that heats the internal copper planes up before applying desolder-temperatures to the capacitor leads. It’s still quite tricky tho as you would want to preheat as much as possible, but at the same time not weaken all the other parts on the board by heating them up too much.
If you need to swap the capacitors out beacuse they are already bad/defective, it can help if you use pliers to cut open the capacitor first, reduce it down to the two lead wires beeing seperated, then you can heat and remove them individally. Least stressful for the board and all the other components.
Motherboard caps are usually attached the PCB ground plane which soaks up heat from the soldering iron.
Pre-heat the board (heat gun) and you should have a better time of it.
BTW, if you design a PCB without thermal reliefs, especially a large multilayer PCB, I’d like to recommend a long walk for you on a certain pier I can recommend.
Modern PCB manufacturing has no real need for thermal reliefs, especially with all the SMD in use. If the design still uses through hole, maybe there’ll be some benefit — but it’s best to avoid through hole.
I have a dev board sitting next to me that was produced and designed within the last few months. I can assure you, it has through hole components. 0.1″ expansion headers, power switch, power jack, ethernet jack, micro-usb jack, db9, OLED display, probe attachable test points, etc.
You seem to be thinking of thermal reliefs for vias. Really don’t need it unless you are planning on putting a pin through a via for devel. Really a rare thing to do, especially given how small vias are now.
Hot air gun what a relief … for moment i was gringing seeing the animated .gif and thinking it was some kind of soldering iron with a sucking pump. God how many solderpads got killed by that because the sharp hot edge scraped over the pcb. I hated that kind of repairs.
As cool the vidio is i would have unscrewed the pcb from its tray and would have it set up in a way that the hot still liquid solder can short out something on the backsidewhen its blown out.
I was doing similar just this weekend with some old computer motherboards and a hardware store bought heat gun.
It might be possible to use a lighting dimmer switch to reduce the power a bit, although my unit has three settings (one being off), and I’ve managed to nab quite a few PCB components and sockets that way. There’s one PIII-era server motherboard that’s going in the rubbish which has only an ISA slot, a 64-bit PCI slot and a coin cell battery holder left — all other components de-soldered.
you should totally be able to use a lamp dimmer control (with a GOOD heatsink) for proportional heat control from a standard heatgun – the coil is a resistive element and the blower is a small universal motor with smoothing capacitors
If the DIP is known bad and/or expendable (most are), then use a fine pair of side cutters and cut all the pins away from the DIP package. This makes removing the remaining pins trivial no matter what the method.
brb getting a hot air soldering station
That sound of the pump is so annoying and gets on ones nerves so quick. I wonder if there is a hot-air gun made that uses a different type of pump. I know the simple membrane at mains frequency ones are simple and cheap, but surely mankind has though of a more luxury and less annoying solution, or did they?
The cheap squirrel cage fan in the handle type hot-air stations work just fine.
What sound? It must be somewhere above the frequency range I hear continuously(tinnitus). I was just wondering this morning, if they came up with a cure for it, how disturbing would it be not to hear that shit anymore?
I have a hakko FR-810. It uses a turbine pump, and is extremely quiet. on it’s lowest setting it doesn’t make a sound, on it’s highest setting there is a light whirr, but nothing like that of the diaphragm pump most hot air guns use. Bonus points for this Hakko for being cheap (for a professional), and one of the best hot air guns I have ever used.
In fairness to Hakko– it really is very quiet. I had the camera on a small tripod about 4″ from the board for the macro focus to work, so the mic was *really* close to the air turbulence hitting the parts. The narrow nozzle on the tip also contributes to the noise, but raises the pressure of the air stream for blowing the holes clean. I have a little vacuum pick-up pencil for SMT parts and that’s actually louder than the Hakko 850 when I use both simultaneously to pull SMT parts.
Clay,
What temperature did you run the Hakko at? I have some really old and precious RAM chips I need to recover, the PCB is not important, but the RAM is.
Martin…
I have it set to about 525°F at the nozzle (checked with a thermocouple). When IC recovery is paramount, I do the same technique, but from the *back* of the PCB. (That way, you have the PCB, plus a little air gap plus the encapsulant protecting the die. It’s a little slower, but the temperature ramp in to the IC is more gradual and it’s largely protected from the hottest air. The old leaded solder will probably flow out under ~400°F, so you’re really not stressing the IC too much. I’ve done *lots* of component salvage this way (literally 1000’s of parts) and never had one die in the process. If you’re really concerned, a thermal imager can give you a pretty definitive view of the heating (even the little ~$150 FLIR ones for the iPhone or whatever). I just try to keep the nozzle always moving to keep things heating up evenly and gradually ramp the temperature up and down to minimize thermal stress on the package/leadframe/bondwires.
Well it’s the cheapest option I think and most people seem to be fine with it and pick the model themselves, it’s not something you can really fault any company for as such.
I’m just sensitive to it I guess.
It’s incidentally the same type of pump used by millions of people with aquariums, showing that many people don’t mind.
When I want the chips and not the PCB I just cut the board up with some large clippers. They tend to break neatly around the pins and free components quickly.
In my opinion it really depends on the used solder and its melting temperature. modern led free stuff seems t have a higher melting temperature and it makes the repair harder. I tried to replace a row of headers on an arduino once, the board got a brownish color in that place before the solder melted.
Happens all the time. Must be the PCB silkscreen as well. I have been “browning” a lot of pins but never had problems at the end. Got more trouble trying to unsolder stuffs.
Yes iirc the lead in solder was addd to lower the melting point of the solder and the newer ones have a different composition with a bit more silver (i could be wrong though). We sometimes had some older electronics for repairs and had to keep an eye out for the higher temperatures.
I’ve never had a problem with a solder sucker + holding the iron diagonally to wedge between 2 pins. 2 pins at a time things go fast.
Unless it’s lead-free.
Used regular iron (no need for hot air) and medical neddle on the pins on the other side of PCB. Neddle was narrow enough to go into hole thus “releasing” chip pin from pcb. Cheap and easy (but slow).
The Hakko 808 solves all these problems (and more!)
The irony in the video is that that MT4264 RAMs are not worth saving. In my experience with repairing old Commodore systems, these RAMs tend to fail often, usually not a total failure but with a few bits stuck to ‘0’ or ‘1’.
So when I get an old system with MT4264 and one of them has gone bad, I replace all of them (with the cutting off the pins method) and throw them out. If you replace only the bad one, you have a good chance that the next one will die soon.
Agreed! I think that literally every device I’ve run across with those MT4264’s has had RAM problems. (They’re the cause of “sparkly” graphics in Atari I,Robot arcade games, and every Atari XE computer that I’ve had RAM failures on has had them inside when I investigated.) I can pull a chip in about ~20 seconds with the hot air, which *seems* faster than snipping it and pulling the pins individually, so I stick with it when I can. (Modern boards or multi-layer boards without generous through-hole diameters are a lot harder.)
Can anybody confirm if any of the super low cost fan based soldering stations can push the solder from the pins? I am thinking the fan cannot create such pressure.
Dyson should design a pump for the desoldering station : would look cool and would be silent (and effective).
There must be enough thermal mass in that board to hold the heat that is being dumped on there. I’ve rarely ever seen hot air rework go so easy on a dip without low melt solder. That or he’s reworked that board 500 times and already knows the magic point at which solder reflows and board doesn’t melt.
No trickery! (Seriously, why would anyone bother to fake that? ;-) I’ve been using this to pull and re-use parts since the 90’s and I’ve done it a *lot*, so I probably do make it look a bit easy– not my first rodeo. The other thing I do sometimes is just pull the chips with air all at once and then go back on a second pass and blow the holes clean– that’s usually slower because you do have to get the local temperature up to the reflow point from scratch, but the Hakko does it in a few seconds. Here’s that technique on an old video I did (~2010) on a Williams arcade game board: https://youtu.be/e_LlGOIDQwQ
Almost as goo as this:
https://www.youtube.com/watch?v=7pVPg8ZJ_2c
The computer’s a 130XE actually. I know it’s illustrative purposes only, but those MT Ram chips of that era are infamous for being unreliable and common advise in Atari and retro computing circles is to replace them whether they’re bad or not.
Nice and quick method – another safe method that gets little mention to remove DIPs is to use a traditional iron, apply to the pins keeping the tip off the board. Use a solder sucker from the other side. Don’t do too many adjacent pins in succession to prevent too much heat buildup. Takes about 10-15 seconds per pin though which is a lot slower than what’s going on here.