Soldering / De-soldering PCB help needed

LordRodders · 9 Jan 2020 at 21:51

Hi, I’m trying to desolder a pcb board but every time I try to it seems to be sucking the contact points off with it also leaving me nothing to solder to when done.

and ideas ?

Zefan · 9 Jan 2020 at 22:01

Some pads can be very sensitive but unless you have a lot of experience the likelihood is that you're simply overheating the board. Assuming you're not too experienced, you should try to apply heat for the minimum amount of time possible. The most common reasons for this are failing to add fresh solder to the working joint to allow heat to quickly transfer, and not using solder braid/flux correctly.

drakulton · 9 Jan 2020 at 22:05

What are you using to do it. A hot air gun or an iron? Sounds like more heat needing to be applied to the component, and heat kept there while the component is removed from the pad.

rhysduck · 9 Jan 2020 at 22:28

As above really. I find desoldering wire helps on sensitive pads

jsmoke · 9 Jan 2020 at 22:30

Are you using flux?

LordRodders · 9 Jan 2020 at 22:49

drakulton said:
What are you using to do it. A hot air gun or an iron? Sounds like more heat needing to be applied to the component, and heat kept there while the component is removed from the pad.

An iron, its on a Xbox one controller pcb

LordRodders · 9 Jan 2020 at 22:50

jsmoke said:
Are you using flux?

Didn’t use flux no, it’s on route in the mail

drakulton · 9 Jan 2020 at 23:00

If you're trying to remove small brick shaped components like resistors, caps and diodes that are soldered at each end, then it will help by linking the two soldered ends with solder, so that both ends are heated at the same time so you can remove them without yanking a pad off.

LordRodders · 9 Jan 2020 at 23:07

drakulton said:
If you're trying to remove small brick shaped components like resistors, caps and diodes that are soldered at each end, then it will help by linking the two soldered ends with solder, so that both ends are heated at the same time so you can remove them without yanking a pad off.

It’s the analogs I’m trying to desolder mainly

vanpeebles · 10 Jan 2020 at 07:59

Use a good quality soldering iron with a heat controller. I dab a dot of rework jelly on the bit to desolder, then hold some soldering braid over the spot then put the iron on top. Or if it's a lot of solder to remove, dab of jelly then use a good quality solder sucker, remove any left overs using the braid.

LordRodders · 10 Jan 2020 at 08:05

vanpeebles said:
Use a good quality soldering iron with a heat controller. I dab a dot of rework jelly on the bit to desolder, then hold some soldering braid over the spot then put the iron on top. Or if it's a lot of solder to remove, dab of jelly then use a good quality solder sucker, remove any left overs using the braid.

Thankyou! Never knew about that rework jelly, keeps it liquid form longer ? any ideas on what temp so the iron be ?
thankyou

vanpeebles · 10 Jan 2020 at 08:12

On my Hakko, I usually have it set to around 350 degrees.

vanpeebles · 10 Jan 2020 at 08:13

http://www.hakko.com/english/hikaru/pages/

Have a read of that, great fun and very informative.

uncle_rufus · 10 Jan 2020 at 08:53

One other thing not mentioned... if you really can't desolder without ruining the contacts (which does happen sometimes even if you try everything to do it "right") - you can always just superglue the new component in and use wire to re-make the connections to the new components (by following the traces and then connecting the leg of the new component to the legs of any components that are meant to be connected to it by the now damaged trace) - hope that makes sense!

vanpeebles · 10 Jan 2020 at 09:02

uncle_rufus said:
One other thing not mentioned... if you really can't desolder without ruining the contacts (which does happen sometimes even if you try everything to do it "right") - you can always just superglue the new component in and use wire to re-make the connections to the new components (by following the traces and then connecting the leg of the new component to the legs of any components that are meant to be connected to it by the now damaged trace) - hope that makes sense!

Yes, sometimes a leaking capacitor will eat away at the contact and it will just drop off. I had to do this on my x68000. I'm currently restoring a PC Engine Duo that has a load of damaged pads

LordRodders · 10 Jan 2020 at 10:39

Any one have any links for a decent iron but not too much money? Preferably sub £100

Feek · 10 Jan 2020 at 10:42

LordRodders said:
Any one have any links for a decent iron but not too much money?

How about this?

/edit - Edited the link from the 3-in-one to the 2-in-one as you probably don't need the PSU.

BusError · 10 Jan 2020 at 10:47

One good trick is not to try to desolder as-is, get some nice LEADED solder, and ADD solder first, before desoldering. Lead-free solder from the original PCB can take a LOT of it and will reflow rather badly, adding solder will make it more maleable and add flux too.

vanpeebles · 10 Jan 2020 at 11:25

Yes, I only use leaded solder. Also a small chisel tip is better than a point, it gets the heat down better and easier to place.