Recovering SMD parts for recycling, pain in the..... - Page 1
Forum section: electronics / repair

author: Lightages
author_rank: Unknown
timestamp: February 10, 2015, 04:55:40 am
content: I had a couple of routers die recently. They happen to have some nice parts on the, specifically some TXCOs. The problem is that they are SMD parts and appear to be the only parts on the boards that were glued down before soldering. I tried heating one up with my hot air gun and all I accomplished was killing the part on not getting the part off of the board.What glues are used typically? Cyanoacrylites that can be dissolved first with acetone? What other types?I would really like to recover these parts. I know of Chipquik but it is a bit expensive for most parts.Any other tips for salvaging parts from boards?

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: February 10, 2015, 05:11:09 am
content: I use two irons (Hakko 936 with 907 handles and some big tips) and bring the heat from all sides at once. I don't know why those parts would be glued down. If it's the usual 5x7mm or smaller oscillator case, the two-iron approach should work.But what is the reason to want to do this? Are parts very expensive in your part of the world?

author: Lightages
author_rank: Unknown
timestamp: February 10, 2015, 09:52:30 pm
content: Parts aren't that expensive, it's just that I prefer to recover special parts if I can. The biggest problem here is availability. It can take me months for mail to arrive so if I see some good and relatively rare parts it is nice to recycle them. Also a TCXO that has been running for years will be really stable now, maybe not so stable after being ripped from a circuit board.

author: mazurov
author_rank: Frequent Contributor
timestamp: February 10, 2015, 11:41:22 pm
content: High speed digital boards typically have several power/ground planes which conduct heat very well. You won't be able to counter it with the soldering iron since the contact area will be too small. The easy solution is to increase the heating area so that the copper planes that were stealing the heat will work to your advantage. Use a preheater of some kind - plain old hot plate heated up to 20-30 degrees below melting point of solder is all that is necessary. Place your board on the plate, wait 30 seconds then solder as usual. This ->http://mightyohm.com/blog/2009/01/diy-pid-controlled-soldering-hotplate/is even better. Here is mine ->https://plus.google.com/114645657478782700234/posts/hm3boiCHiqE.

author: mazurov
author_rank: Frequent Contributor
timestamp: February 10, 2015, 11:41:33 pm
content: High speed digital boards typically have several power/ground planes which conduct heat very well. You won't be able to counter it with the soldering iron since the contact area will be too small. The easy solution is to increase the heating area so that the copper planes that were stealing the heat will work to your advantage. Use a preheater of some kind - plain old hot plate heated up to 20-30 degrees below melting point of solder is all that is necessary. Place your board on the plate, wait 30 seconds then solder as usual. This ->http://mightyohm.com/blog/2009/01/diy-pid-controlled-soldering-hotplate/is even better. Here is mine ->https://plus.google.com/114645657478782700234/posts/hm3boiCHiqE.

author: Nerull
author_rank: Frequent Contributor
timestamp: February 11, 2015, 03:09:56 am
content: They're often epoxies. The only chemicals that would attack them would likely also eat your chips.One major manufacturer recommends:Quote

author: Lightages
author_rank: Unknown
timestamp: February 11, 2015, 04:54:26 am
content: Well I used a hot air gun set to 250C first and the chip wouldn't budge, It still worked after ten minutes of heating. I then bumped the temperature up to 300C and it still wouldn't come free even after 10 minutes. Yes the board got that hot locally. After that abuse the chip had been fried.The adhesive under the chip looks to very clear and transparent. I looked up some pricing on similar chips and it seems they are worth saving, around $30 in one off prices.So I guess I need to try some solvents first, acetone or toluene. The chips are ceramic packages with metal caps so I think it highly unlikely I can kill them with harsh solvents.

author: amyk
author_rank: Super Contributor
timestamp: February 11, 2015, 08:23:47 am
content: If you're not interested in saving the board then how about cutting the component out and then carefully grinding the remains of the board from it?

author: Lightages
author_rank: Unknown
timestamp: February 11, 2015, 12:29:11 pm
content: Yes,vi have been thinking of doing that to buy it is such an inelegant way.

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 11, 2015, 01:09:51 pm
content: if there is picture, it is easier to advice the angle of attack. my imagination tells me... paper knife.

author: andy2000
author_rank: Frequent Contributor
timestamp: February 12, 2015, 01:08:32 am
content: I've had good luck heating the board from the bottom using a hot air gun. That way the chip isn't exposed to the full output of the hot air gun. It takes a lot more heat, but if you don't care about the board it doesn't matter. It should be possible to pry the chip off as soon as the solder melts and the glue softens.

author: ion54
author_rank: Contributor
timestamp: February 12, 2015, 03:14:37 pm
content: I have recovered some chips by using a cheap hot air gun (not for electronics) blowing at full blast on the back of the board. It got to the point where the PCB became soft, but the parts de-soldered and they were still good to use after that.

author: wagon
author_rank: Frequent Contributor
timestamp: February 12, 2015, 08:40:12 pm
content: I've used an air-lpg blowtorch for such purposes. Safety glasses on, in a well ventilated space. Heat the opposite side of the board (it will catch fire and stink!). Give the board a smack and the parts you want will fall off! Then throw the board outside so the fire can go out and the stink goes away. Obviously, the board will be stuffed now. The other advantage, quite often the legs won't have much solder on them, so there isn't much cleaning up to do.

author: mzzj
author_rank: Super Contributor
timestamp: February 13, 2015, 09:18:19 am
content: Quote from: wagon on February 12, 2015, 08:40:12 pmYes, it works but the stink is horrible. Well ventilated fume hood rated för nuclear waste would be the minimum