Method to Remove All ICs from a Board - Page 1
Forum section: electronics / repair

author: mapleLC
author_rank: Frequent Contributor
timestamp: July 02, 2022, 11:06:10 am
content: I would like to experiment with recycling a circuit board that has numerous op amps that are useful to me. I can do this once, and its boring and time consuming, but ok then it gets old because it wont be the first and last board I will want to recycle.Its become time consuming, and some of the things I have read are simply not working. For example, a paint heat gun and a bucket, followed by tapping the board when upside down... like 2 little caps came off after the board browned in an area. You're doing it wrong I guess?Are there any better ways to do this other than time consuming, dirty, and sometimes unsuccessful methods like this or a simple iron and wick, or soldering station heat gun?I had the idea of using the oven, a board upside down, sustained heat and gravity to see if pieces would slowly shower down. I worry I will cook all the parts.So help would be appreciated

author: xrunner
author_rank: Super Contributor
timestamp: July 02, 2022, 11:09:22 am
content: What about these types of soldering iron tips - the ones that touch all the pins at once?https://www.circuitspecialists.com/solderingtips

author: SMdude
author_rank: Frequent Contributor
timestamp: July 02, 2022, 11:42:59 am
content: I have done it using a normal hot air gun.Practice with some boards that just don't matter. I just heated it up and turned it upside down and whacked it on something.Heating the board upside down in the oven won't work as the surface tension of the solder will keep the parts in place. You just need to be a little more violent, like you just don't care.As for trying to desolder using solder wick, nope, flood both sides with solder and swap the iron back and forth until you can slide it off.If you have a hot air station as well you can use hot air to assist and use the soldering iron as above.

author: mapleLC
author_rank: Frequent Contributor
timestamp: July 02, 2022, 12:24:31 pm
content: So seriously, I'm just not waking enough neighbors? Ok then. I will try banging harder.

author: jpanhalt
author_rank: Super Contributor
timestamp: July 02, 2022, 12:44:54 pm
content: If they are through hole IC's, you may need to push a little. I have used a propane torch (soft flame) to do that. It was an old frequency generator, and I got the RF cans off easily too.

author: SMdude
author_rank: Frequent Contributor
timestamp: July 02, 2022, 12:54:35 pm
content: Quote from: jpanhalt on July 02, 2022, 12:44:54 pmYes! I remember back in the 90's scrapping some TV boards, used the oxy torch and a few good whacksProbably still have those parts somewhere, could be worth something these days..Bugger the neighbors Maple! Though mine are all several hundred meters away so they don't hear much from me, even at midnight.

author: pqass
author_rank: Super Contributor
timestamp: July 02, 2022, 01:44:23 pm
content: Quote from: mapleLC on July 02, 2022, 11:06:10 amUse a solder pot. See 2:00 into:

author: mapleLC
author_rank: Frequent Contributor
timestamp: July 02, 2022, 03:06:43 pm
content: Quote from: pqass on July 02, 2022, 01:44:23 pmThats the ticket... I wish it didn't need that 3rd world looking soup of molten solder to use it, but he got those parts off like nothing.

author: RoGeorge
author_rank: Super Contributor
timestamp: July 02, 2022, 03:16:40 pm
content: If you have an electric grill, put the PCB above the grill at a small distance, as if it were meat, and let it heat until the solder starts to melt, but no more than 2-3 minutes.After that, most of the components can be picked by tweezers and pliers. If you don't care which part is coming from where, just take the heated PCB from above the grill and hit it sharp to the floor or to a metal tray. Most of the SMD parts will just fall from the PDB into the underneath tray.

author: pqass
author_rank: Super Contributor
timestamp: July 02, 2022, 03:27:40 pm
content: Quote from: mapleLC on July 02, 2022, 03:06:43 pmYeah, that's a lot of solder! The slag/crap is easily scraped off, though.I haven't tried this myself but maybe you can use a wide yet shallow aluminum dish on hot plate?

author: mapleLC
author_rank: Frequent Contributor
timestamp: July 03, 2022, 01:35:46 am
content: Quote from: pqass on July 02, 2022, 03:27:40 pmI looked and this 100mm size is the largest until they get way more expensive. Frankly this is not even a product, its a hot plate. I could do this on my stove but le wife would balk.Noodling this a bit...A cast iron frying pan holds heat well, and more solder would create a larger pad to remove from. A $39 hot plate and a cast iron skillet would give you enough room for a pretty substantial board on and remove parts. You'd need several KG of solder to fill it, so there is that.

author: james_s
author_rank: Super Contributor
timestamp: July 03, 2022, 01:41:05 am
content: I do it with a heat gun. I heat up a section of the board, then whack it on the bench and the parts drop right off.

author: pqass
author_rank: Super Contributor
timestamp: July 03, 2022, 06:08:45 am
content: Quote from: mapleLC on July 03, 2022, 01:35:46 amEven if you use a large diameter  skillet you don't have to fill it as long as your board can fit within. But you'll need to hold the board from above; eg. stiff wire through a couple of holes. And you'd only need 1/4" depth of molten solder at most. Don't use your good stove for this; use a dedicated hot plate. I wouldn't want this anywhere near my kitchen or indoors.

author: Messtechniker
author_rank: Frequent Contributor
timestamp: July 03, 2022, 06:15:01 am
content: Quote from: james_s on July 03, 2022, 01:41:05 amDoing the same here too.

author: tkamiya
author_rank: Super Contributor
timestamp: July 03, 2022, 06:33:10 am
content: There is a product called "ChipQuik." It's a special alloy which melts at ridiculously low temperature and mixes with solder remain in liquid state for long time. You could apply ChipQuik to all 8 leads of OP AMP, and simply pull out the chip. Be forewarned though, this stuff is rather expensive. But if you are working with rare or valuable chips, it's a good stuff.

author: vk6zgo
author_rank: Super Contributor
timestamp: July 03, 2022, 06:43:56 am
content: Quote from: pqass on July 02, 2022, 01:44:23 pmSo, in the words of the old song: "What we need is a great big melting pot"?

author: jpanhalt
author_rank: Super Contributor
timestamp: July 03, 2022, 10:04:48 am
content: I might suggest wearing safety glasses.

author: bd139
author_rank: Super Contributor
timestamp: July 03, 2022, 11:16:35 am
content: I would leave them on the board until you need them. Then desolder them one at a time.I would not want to desolder everything off the attached boards for example!

author: mapleLC
author_rank: Frequent Contributor
timestamp: July 03, 2022, 12:19:16 pm
content: Quote from: bd139 on July 03, 2022, 11:16:35 amThat seems like a large scale time suck. It saves you the minimal amount at the beginning, but requires large scale cataloging. Then you remove that all important chip, forget, then 5 years later need one?

author: bd139
author_rank: Super Contributor
timestamp: July 03, 2022, 02:07:46 pm
content: They all come out of one bit of kit so I just scan the service manual. I pulled all the precision parts, high value bits and things I ran out of already with a desolder station. Everything else I will go looky findy if I need it.

author: mapleLC
author_rank: Frequent Contributor
timestamp: July 03, 2022, 03:52:49 pm
content: Ok so I went out this morning and got this.I put all the old solder I had in it, but its nowhere near enough.Once it melted the rosin was easy to wick with a paper towel, though its smoky and stinks. Do this outside.I also bought a small cast iron pan for little jobs. The big one is to test out doing entire boards.My first test was pretty positive, the board tends to float on the solder, parts that are not bent in place come right off, but the ones with bent leads tend to sink the board in the solder with force, so there has to be a way to improve this.

author: fourfathom
author_rank: Super Contributor
timestamp: July 03, 2022, 06:29:10 pm
content: Quote from: pqass on July 02, 2022, 03:27:40 pmDo NOT use an aluminum dish or skillet! I learned this the hard way when I was 12 years old, melting old lead tire-weights on the stove. (How did I ever survive my youth??? So many "learning experiences"!)

author: jpanhalt
author_rank: Super Contributor
timestamp: July 03, 2022, 06:29:15 pm
content: You can buy pure 63/37 solder sticks without flux. Much cheaper last time I did it. You can also buy lead ingots in various sizes. It appears solder ingots are about $12 to $15/# now. Spot price for lead (commercial market volume) is about $1/#.I would be worried about Teflon long term at soldering temperature. My solder pot is cast iron. Cast iron baking dishes (e.g., for flat bread/corn bread) are at Walmart.

author: RoGeorge
author_rank: Super Contributor
timestamp: July 03, 2022, 07:17:37 pm
content: I didn't use any pool of melted solder.Just put the PCB in the tray and wait a couple of minutes for the solder on the PCB to melt. The electric grill was about 1500W (for example to unsolder a whole PC AT motherboard at once - some plastic connectors might deform a little, but the ICs and other components will desolder OK).

author: mapleLC
author_rank: Frequent Contributor
timestamp: July 03, 2022, 07:48:12 pm
content: So lay the board on the skillet and heat it up?Its hard to control the temperature.

author: RoGeorge
author_rank: Super Contributor
timestamp: July 03, 2022, 08:27:55 pm
content: Yes, just put some hit into the PCB. You don't need to precisely control the temperature.When the solder on the PCB starts to melt, it means the temp is around 200-300*C. Lift the PCB, and either hit the board in a second tray to collect the parts that will fell because of the hit, or else pick them one by one while keeping the board lifted above the heat source. Practice on smaller or less valuable boards first, or maybe break a large PCB into smaller pieces so make more tries.

author: mapleLC
author_rank: Frequent Contributor
timestamp: July 03, 2022, 08:54:19 pm
content: It's not working. I just has a smelly garage and driveway.

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 03, 2022, 09:13:04 pm
content: Not sure if it has been suggested already? A hot plate!

author: jpanhalt
author_rank: Super Contributor
timestamp: July 03, 2022, 09:19:26 pm
content: 1) Get yourself some TM-902C TC thermometers. They work.Here's one source:https://www.ebay.com/itm/254840557899?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=254840557899&targetid=1262749491342&device=c&mktype=&googleloc=9015294&poi=&campaignid=15428034462&mkgroupid=133947154481&rlsatarget=pla-1262749491342&abcId=9300763&merchantid=108350853&gclid=EAIaIQobChMI5tzzr9Dd-AIVF8LCBB17aQRUEAQYAyABEgIKEfD_BwE2) I love the smell of chemistry. They probably won't kill you. After I retired, I volunteered at a local college. For some reason, that wonderful smell was missing. FWI: I trained in Ira Remsen's laboratory, literally. His body was interred in the stairway to the second floor. I rescued and saved an old autographed image by another famous chemist to him. He tasted everything. We didn't quite do that, as we has IR, UV, and 60 MHz NMR by then. But still, one's senses are important.

author: Zero999
author_rank: Super Contributor
timestamp: July 03, 2022, 09:36:12 pm
content: I'm going to be boring and say it's not worth it most of the time. I used to do this when I was a teenager and couldn't get hold of the components. Nowadays I don't bother, unless it's something expensive or exotic.

author: mapleLC
author_rank: Frequent Contributor
timestamp: July 04, 2022, 01:14:13 am
content: Quote from: Zero999 on July 03, 2022, 09:36:12 pmFrame that a bit? What is worth soldering off?

author: Messtechniker
author_rank: Frequent Contributor
timestamp: July 04, 2022, 05:21:49 am
content: In view of today's often very limited availability of even trivial parts, I am glad that over the past 3 centuries, I did salvage parts from my old projects and from other PCBs, motherboards and PSUs, in particular. Good enough for tinkering, prototypes and testing things.

author: Zero999
author_rank: Super Contributor
timestamp: July 04, 2022, 07:43:15 am
content: Quote from: mapleLC on July 04, 2022, 01:14:13 amVery little. If you can buy it new from RS Components, Farnell, Mouser, Digi-Key etc. and it's not crazily expensive, don't bother. It's time consuming and then there's a risk the parts you salvage are bad and you find yourself wasting even more time wondering why a circuit won't work and trying to fault find it.

author: RoGeorge
author_rank: Super Contributor
timestamp: July 04, 2022, 08:25:50 am
content: Quote from: mapleLC on July 03, 2022, 08:54:19 pmI'm sorry to hear that grill didn't work well. Mass desoldering worked pretty well with my grill and 2-3 motherboards scrapped like that, and once I did that indoors with an open window. It was some smell, but not fumes. Maybe you are keeping the PCB too close, or maybe your grill is too different. Mine was for grilling meat, with a serpentine red hot heating element, something like this:https://www.emag.ro/gratar-electric-dimensiune-47x35-cm-2000w-z-line-2867-z-line2867/pd/D7QN0DMBM/If the PCB solder melts faster than 2-3 minutes, then it's too much heat and the PCB needs to stay higher above the grill. Might depend the type of PCB, too, I only used the grill method a couple of times with relatively flat PCB like a PC motherboard, not with PCB populated with plaenty of wires and electrolythics, like for example a PC power supply has.Here's a few scavanged parts, note how the big connectors are slightly melted, still usable, but meh. So far the scavenged parts I've used (in hobby projects) or measured out of curiosity (i.e. the power MOSFET in the pic) were OK.

author: mapleLC
author_rank: Frequent Contributor
timestamp: July 04, 2022, 04:26:12 pm
content: What are others using for snipping boards into smaller pieces? I dont like to cut them, its too much dust and cancer.I have a pair of sheet metal snips, but their effectiveness is limited, and it doesn't really want to cut the board.

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 04, 2022, 07:17:18 pm
content: Quote from: Zero999 on July 03, 2022, 09:36:12 pmDitto. But given the ongoing shortage, I'm not surprised that this activity is getting popular again.As I said, I'd suggest using a soldering hot plate - it will at least regulate to a reasonable temperature that won't kill your components and burn stuff with toxic fumes (at least not too much).You can find cheap ones these days. You can alternatively use some cooking plate if you can have it cheaper. Those are also temp-regulated, all you need is to figure out the temperature with a thermometer.

author: bd139
author_rank: Super Contributor
timestamp: July 04, 2022, 08:24:35 pm
content: It makes sense if you're in a Chinese sweatshop selling refurbished parts for premium prices. It doesn't make sense if you an afford a garage and a hot plate to do it in.I've got to clear out a whole house of someone who hoarded boxes and boxes of desoldered parts, valves and all sorts in their garage and it's all rotten, corroded and going in a skip anyway. Thousands of hours of life wasted.

author: mapleLC
author_rank: Frequent Contributor
timestamp: July 05, 2022, 08:03:51 am
content: Quote from: Zero999 on July 03, 2022, 09:36:12 pmQuote from: SiliconWizard on July 04, 2022, 07:17:18 pmIts also the weirdo millennial crowd that uses magical thinking to will things in to being recyclable that are not.Germane to a few posts above, my interest in building a small parts inventory of relatively known components from teardowns of things related. Its not like I tore down a microwave board for parts to use for fixing a meter.More than the money, its the annoyance of constantly needing to pay shipping for a single tiny part and the waiting period when you have nailed a problem and want to just see it fixed. For this reason, I started to break down boards from stuff that was not savable. Whether it yields any useful pieces is to be seen.Quote from: bd139 on July 03, 2022, 02:07:46 pmThis photo was helpful for what to look for of value, it's kind of fun to find these if only to collect them. Is there more out there like this? What kind of boards tend to have these kinds of precision components?

author: bd139
author_rank: Super Contributor
timestamp: July 05, 2022, 08:22:56 am
content: Look for test gear on ebay that no one knows what it is, is application specific and isn't interesting. Check the service manual for it and look for parts. Extract and reuse.This was from an HP 3776A PCM test set. Lots of other parts in there which can be used to repair other more useful gear.

author: Shock
author_rank: Super Contributor
timestamp: July 05, 2022, 08:27:21 am
content: The valves could be worth good money, obviously only components that have been discontinued or are expensive are worth it. I prefer to keep boards whole but I've scrapped plenty. High quality large caps aren't cheap.Smd components come off easy with an underside preheater and hot air. For through hole caps fastest way is blade tips (if the leads aren't clinched) with a bit of preloaded solder, this way you hit both pins at once.

author: mapleLC
author_rank: Frequent Contributor
timestamp: July 05, 2022, 10:19:29 am
content: Quote from: bd139 on July 05, 2022, 08:22:56 amThank you. I have more of an issue with parts identification of the less obvious components, so visuals help. That's a huge piece of gear to yield that many parts, unless that's just a fraction. I can understand if its free, but not worth spending money on. It makes sense that if you repair within the HP ecosystem then other units are good to have.

author: Zero999
author_rank: Super Contributor
timestamp: July 05, 2022, 12:24:25 pm
content: Quote from: mapleLC on July 05, 2022, 08:03:51 amYour best bet is to bulk order a load of commonly used parts.Start with:E12 resistors from 10R to 1M, with extra 1k, 10k and 100k because they're very common.E3 capacitors from 100pF to 1000µF, with extra 100nF and 10µF because you'll find those everywhere!BJTs: BC338 and BC328, BC139, BD140MOSFETs: 2N7000 and IRL3705Voltage regulators: LM317, LM78L05Op-amps LM358, TL072, NE5532, OP07Logic ICs, not needed so much now, but still handy: 74HCT14 Schmitt trigger inverter, handy from shifting 3V to 5V and building oscillators, HEF4504 handy to shift 5V to 12V.LEDs: various colours.Microcontrollers: choose a range with a cheap and widely available programmer and preferably GCC support, so you're not tied to it. Many people here like AVR for that reason, although I've not used them myself. I have a stock of old PICs, but they're not supported by GCC and have quirks, so I wouldn't recommend them to a beginner.Miscellaneous: switches, relays, small speakers, buzzers etc.Power supplies and test equipment.Consumables such as solid core, insulated wire, flexible cable, heat shrink tubing, strip or perf board etc.