How to desolder an 8-pin relay without a soldering pot or solder sucker? - Page 1
Forum section: electronics / general

author: Del Tapparo
author_rank: Newbie
timestamp: May 11, 2014, 11:03:42 pm
content: I have 8 pin relays on my PCBs that I can't remove from the board. I have a ZD-915 desoldering station, which works great on most things. But after sucking the relay pins, they are still soldered to the component side of the board on the through hole pads.I would like to find a soldering tip or iron that will heat up all of the pins at once. It seems like Dave mentioned something like that once? I don't want to use a soldering pot. Anybody know of an iron or tip that would do the job? I have a Weller soldering station, but can't find any Weller tips like that.

author: jamesglanville
author_rank: Contributor
timestamp: May 11, 2014, 11:39:40 pm
content: YMMV, but if it's just a one-off job, I often just heat up a scrap of metal with a blowtorch, then use that to melt a whole line of pins. You'd want to blob a bit more solder on first though if you've removed most of it, so you make a decent contact.

author: mariush
author_rank: Super Contributor
timestamp: May 11, 2014, 11:50:36 pm
content: Add some liquid flux on the side where its still soldered, maybe with a syringe needle under the relay.Add solder to the pins, making sure enough flows to go to the other side and mix with that solder.Get your desoldering gun and gently do circles around the pin pressing it to the sides to make sure it's loosened from all the sides of the hole, then suck the solder out.Other ideas... get some stranded network cable or some stranded cable, remove insulation, drop a bit of flux on it and you have a solder wick.Or.. get some solid core wire, put it on the leads on one side, add solder, cover the lead and the pins in solder. Repeat on the other side. Then put your iron at high temperature and alternate between both sides until both sides are liquid.. pull relay off the board.

author: Del Tapparo
author_rank: Newbie
timestamp: May 11, 2014, 11:52:56 pm
content: Quote from: mariush on May 11, 2014, 11:50:36 pmThe component side of the relay is not accessible. That is the problem.

author: scientist
author_rank: Frequent Contributor
timestamp: May 12, 2014, 12:52:15 am
content: Use hot air.

author: David_AVD
author_rank: Super Contributor
timestamp: May 12, 2014, 01:17:37 am
content: Low temp solder ("Chip-Quik") will do the job.

author: pelud
author_rank: Regular Contributor
timestamp: May 12, 2014, 01:53:53 am
content: Mount the board horizontally and create a giant blob of solder that bridges all of the pins. It might waste a lot of solder, but it will practically fall off the board. Be careful as some of the solder will drip through the holes when you pull it off.

author: Pillager
author_rank: Unknown
timestamp: May 12, 2014, 03:18:38 am
content: I recently used hot air (heat gun) to desolder some tricky components. Worked fine, because I didn't need the board anymore. Good thing, too, because it now looks like a piece of toastWhen I don't use the heat gun, I try and rock it out from side to side, heating up blobs of solder on one side of the part simultaneously, then the other. It's often a pain in the ass, but it works.If the holes are large enough, I dip a thin strand of wire in some flux, wedge it in the hole and heat it up again. That gets out most of the solder, and then I wiggle the pin a bit to get it "unstuck".If I have my desoldering station and the part won't come out, I resolder the pins and hold the boards sideways while desoldering, or sometimes I desolder from the bottom, so that gravity works with me. Just make sure to stay on there for a while before sucking away the solder, so that everything heats up well.Dave has a good video on desoldering, using a ZD-whatever. Search youtube.

author: JOERGG
author_rank: Contributor
timestamp: May 13, 2014, 12:47:57 am
content: https://www.google.de/search?q=dil+weller

author: Joule Thief
author_rank: Regular Contributor
timestamp: May 13, 2014, 03:03:37 am
content: are you interested in salvaging the relays only, the board only, or both?

author: Del Tapparo
author_rank: Newbie
timestamp: May 13, 2014, 04:15:40 am
content: Quote from: Joule Thief on May 13, 2014, 03:03:37 amBoth. I did try a few more boards today with limited success using mk ZD desoldering station. Some work, most don't.Thank you for all the tips.

author: Yago
author_rank: Frequent Contributor
timestamp: May 13, 2014, 02:19:53 pm
content: If the pins are in two rows, blob the rows into a single blob each, then walk it out.

author: Joule Thief
author_rank: Regular Contributor
timestamp: May 14, 2014, 07:25:31 am
content: Something along this ideahttp://www.ebay.com/itm/New-Ungar-6948-Desoldering-Tip-For-Removal-Of-IC-Chips-/251448183206?pt=LH_DefaultDomain_0&hash=item3a8b7ac9a6You will need a substantial iron to be successful.

author: bookaboo
author_rank: Frequent Contributor
timestamp: May 14, 2014, 09:55:25 am
content: Quote from: scientist on May 12, 2014, 12:52:15 amThisQuote from: David_AVD on May 12, 2014, 01:17:37 amOr this, or a combination.

author: Joule Thief
author_rank: Regular Contributor
timestamp: May 14, 2014, 11:12:52 am
content: another thought ...maybe a larger diameter tip on the ZD desolder gun to allow for increased airflow thru the pcb.resoldering the remaining joints with leaded solder and desoldering the joint again with the larger tip may prove beneficial

author: amyk
author_rank: Super Contributor
timestamp: May 14, 2014, 11:18:07 am
content: Quote from: Del Tapparo on May 11, 2014, 11:52:56 pmNot sure I understand what you mean... how do you remove the relay after it's been unsoldered? Or are you just wanting to electrically disconnect it from the rest of the circuit?

author: David_AVD
author_rank: Super Contributor
timestamp: May 14, 2014, 11:18:59 am
content: Once you've used Chip-Quik, you'll wonder why the hell you didn't start using it sooner. It's excellent for through-hole and SMD.

author: scientist
author_rank: Frequent Contributor
timestamp: May 14, 2014, 08:11:27 pm
content: Given the length of this thread, I think a flamethrower is necessary.

author: Isamun
author_rank: Regular Contributor
timestamp: May 14, 2014, 08:22:10 pm
content: Your desoldering unit should be capable of performing this operation. I know you've tried, but as others has suggested; try to reflow the joints first with some fresh leaded solder, a high capacity iron and then try desoldering again. Wiggle it good and make sure the entire through-hole is wet before you apply vacuum. Maybe try drenching the joints in flux if you don't succeed at first.Last option is to preheat the board with some hot air. I'm guessing you're pretty close to target temp, so even a hairdryer (if you don't have access to a hot air station/tool) raising the "ambient" by 50 degrees will be a big help.

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: May 14, 2014, 08:58:25 pm
content: turn the temperature on the desoldering station up410+ degrees.

author: Fraser
author_rank: Super Contributor
timestamp: May 14, 2014, 09:34:41 pm
content: Another recommendation for Chip Quick .... I always keep some in the 'last ditch' drawer for when all other standards desoldering methods fail or are not appropriate to the scenario. You will not regret buying some if you work on weird electronics.Some of the worst cases I have had to deal with involve PCB's that have pressure fitted 'self holding' component pins that grip the feed-through liner even before solder is applied. It is almost impossible to remove them with conventional solder extraction tools. Managed it finer with Chip Quick as the solder remains fluid for so long that you can wiggle the pins outSome DIL assemblies are also inserted into feed through holes that are barely a clearance fit and these also present a challenge to conventional desoldering equipment. Hot Ait Guns (for SMD work NOT paint stripping) can be used but you need to be very careful if you want to re-use the PCB afterwards.Fraser

author: Teledog
author_rank: Regular Contributor
timestamp: May 15, 2014, 04:54:08 am
content: I agree with Pelud,Rosin flux the pins, add big blobs of rosin core solder to the pins.Heat each pin & use a BIG solder sucker (I use a big old soldapullt unit) on the pins.{Edit} oops..sans solder sucker!.. Use lots of solder wick/braid, might try a few different widths, ..wipe the braid thoroughly with a flux pen before use & apply with a very hot iron .Any pins/holes that aren't clear after solder(braid) sucking (usually power/ground planes that take a lot of heat to remove), add more flux/solder to those ones..use a decent soldering station BTW (or hot iron) .Then slowly, carefully heat those pins with the blobs of solder while lifting it from the back side,.. a bit/pin at a time.....keep it moving around & wiggling until the the relay /component pops out...again, a bit at a time..don't pull too hard or you'll pull vias/traces.Then finally clear the TH holes with flux & braid & a hot iron.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: May 24, 2014, 12:23:06 am
content: Stained glass supply store.

author: Rasz
author_rank: Super Contributor
timestamp: May 25, 2014, 08:46:03 am
content: 858 hotair starts at ~$35-40, treat yourselfParks and Recreation - Treat. Yo. Selfchipquick, manual solder suckers, big solder blobs, its all amateur hour.All you need is plain soldering iron, hotair and flux. Preheater if its your daily job, rework station if you replace big bgas.