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Lifting solder pads - common issues. What temp gives the best chances of success?

G

Goodguy309

New Member
Oh, the pain/love cycle of owning older equipment!

I just lifted 3 out of three solder pads and admittedly, I'm way out of the days when I had better technique.

Okay, the mea culpa first. In the recent past, I've added new solder before desoldering the joint.

However, it's not always successful.

What is the proper temp to desolder 40 year old equipment?

I'm looking for those that found a better method.
 
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Having the proper desoldering equipment is crucial. I use the Hakko 808 desoldering gun and haven’t had any issues with lifting pads since.
You also can use Soder-Wick or Techspray braid to remove old solder without lifting the pads.
 
^ Fact.

Some board materials just seem to be more susceptible to poor copper bonding. As for a time-at-temperature curve before failure, any "data" you might find is not likely universal. I've also added fresh solder to help with the desoldering process. Counterintuitive as it might seem, less time spent on a joint at higher temperature can sometimes be less stressful to the board.
 
Hopefully it isn't a crappy board.

I'm running the solder/desoldering tools between 650-750F. Had problems starting out with working on old stuff and I made it a mission to do a better job.

Clean the joint of oxidation and contaminants and use decent gear. Sometimes it takes denatured alcohol, sometimes it takes acetone, sometimes it takes a pen "scuff" brush, sometimes it takes some paste flux.
 
I'm just an amateur without the extensive experience of many others here but I've found that even if you are careful, sometimes a trace will lift and the best thing you can do is a repair that assumes the trace is gone, going to the next solder pad in the path or by uncovering some of the copper foiling and making a new path with a wire lead. I've also found that even with a Hakko desoldering gun, I still use solder wick. But I did see a pretty good trick once, where a guy would cut about 1.5" of solder wick, wet it with flux and hold it with a needle nose and then use the soldering iron to remove the excess solder. Seems to work really well when I try it - the flux in the wick seems to just make it far easier to suck up the excess.
 
I'm an amateur as well. You reminded me that I almost never use wick anymore. Some of the wick on my bench has flux in it and some not. It's difficult to diagnose without knowing what the board looks like and what tools, chemicals, etc. is available to work with.
 
Irons vary and I've never measured mine, but I'd never want to get near 700 on a PCB with my Hakko 936. 650 is sort of nominal for me. I usually use the classic Edsyn DS017 Soldapullt because it has the pull time to get the joint clean. IMO, smaller suckers are near to worthless. Naturally, a proper desoldering station will be the best thing if you want to spend the $$. I find they require a lot of cleaning/maintenance. I keep wick around. Sometimes it's the perfect answer but most of the time it heats the joint for too long. My general advice is don't use too small a tip, don't go too hot, use flux, tin well, then get in and get out in a reasonably short amount of time.
 
fast and hot is better than long and kinda hot. Right tips and good station. A iron that has trouble recovering its temperature quickly is a problem. Back in the day I was given advise in the yahoo tektronix group because I was lifting pads regularly. I was told the butchery would continue until I invested in a decent station. I did just that and have had very very few issues in the following years. Also dont scrub on the pads, its kinda a temptation to try to get the heat there but you will just end up wiping it off. .
 
Last edited:
eiraved said:
Having the proper desoldering equipment is crucial. I use the Hakko 808 desoldering gun and haven’t had any issues with lifting pads since.
You also can use Soder-Wick or Techspray braid to remove old solder without lifting the pads.
Click to expand...

In my working days, I designed automated control systems for production machines and some simple test equipment. Schematics and electrical buildout went to our shop.,

I never had to use a soldering iron although I certainly was no stranger.


A few years ago, I decided to recap my Nikko 230 amp. Dozens and dozens of unsoldering pads. I lifted two but I follow some techs on YouTube and they had the more expensive Hakko.

I'm not a repair tech and do 'sfuff' about once a year so I couldn't justify the $240 cost.

However, lifting three pads in a row tells me this isn't fun either!



I
 
ConradH said:
Irons vary and I've never measured mine, but I'd never want to get near 700 on a PCB with my Hakko 936. 650 is sort of nominal for me. I usually use the classic Edsyn DS017 Soldapullt because it has the pull time to get the joint clean. IMO, smaller suckers are near to worthless. Naturally, a proper desoldering station will be the best thing if you want to spend the $$. I find they require a lot of cleaning/maintenance. I keep wick around. Sometimes it's the perfect answer but most of the time it heats the joint for too long. My general advice is don't use too small a tip, don't go too hot, use flux, tin well, then get in and get out in a reasonably short amount of time.
Click to expand...


It's funny you mention about the smaller suckers and this is where I believe my problem started, My smaller one would remove the solder from the pad but leave some in the hole. I then took my big blue one and that's where I lifted the pads.

Had I used the big one first, I wouldn't have had to reheat the pads to remove the component.
 
grey said:
Hopefully it isn't a crappy board.

I'm running the solder/desoldering tools between 650-750F. Had problems starting out with working on old stuff and I made it a mission to do a better job.

Clean the joint of oxidation and contaminants and use decent gear. Sometimes it takes denatured alcohol, sometimes it takes acetone, sometimes it takes a pen "scuff" brush, sometimes it takes some paste flux.
Click to expand...


It's a 40 year old McIntosh so I was quite surprised the pads just dissolved.
 
I never really thought about the pull time of a full-size Soldapullt, but that makes a lot of sense. I use that on things like point-to-point wiring lugs, but almost never on PCBs. For PCB work, the maneuverability of a small hand pump can be hard to beat, and if the pump has a flexible silicone tip, I think the better vacuum seal against the workpiece (compared to a hard tip) can make up for the lesser pull time.

The tool available at DigiKey labelled as Adafruit 1597 is what I use for a small hand pump:

Of course, getting the solder OUT of the pump, and regular replacement of tips (Digikey has those, too) is a pain.

If I'm doing more than a few joints, and if the workpiece is roomy enough, I'll fire up the real (powered pump) desoldering station. Maintenance of those is no picnic, either, though.
 
too much heat, pressure and/or dwell time are what I find causes lifted pads - in any combination. Look up the 1980's pace soldering/rework training video series on YouTube and watch them all, they go into really great detail on technique and pitfalls. I wish I knew about them much sooner than I did!
 
Try melting a small bead of solder on the tip then use the bead, rather than the iron tip, to melt the solder joint then use solder pump to remove. Think the idea is that the bead disperses the heat. OTOH some boards/tracks/... are just bad... Also use low melt solder, ie, not lead free
 
Contact area is key. I have seen (and helped) newbies to the soldering world, and their problem was the tips supplied with their irons were far too small for the size of pads in this old equipment. You want something with a screwdriver (chisel) or angle cut (sloped) tip of 2.5 to 3mm. I also sometimes find it better to heat the solder up and remove the component before removing the solder. Electrolytic caps are great for this, since you can rock them over to one side to get one lead, and then over the other side to remove them, then remove the solder. Depending on the mood, I use a pump type solder sucker, braid, or desoldering tool.
 
leesonic said:
Electrolytic caps are great for this, since you can rock them over to one side to get one lead, and then over the other side to remove them, then remove the solder.
Click to expand...
extremely dangerous to do that.

rock it on the first pad then pull on the cap when heating the 2nd pad. don't rock it on both because if the first leg hasnt cleared, when you lean the cap over, the pressure is enough to push that pad and trace right off the board.(i've done it) i'd never recommend rocking caps to a noob.

leesonic said:
I also sometimes find it better to heat the solder up and remove the component before removing the solder
Click to expand...
i always leave the solder when the leads are folder over tight. i heat it and use a desoldering tool with the blade to pry the folded lead up. i'll suck up the solder after legs are straightened.

leesonic said:
You want something with a screwdriver (chisel) or angle cut (sloped) tip of 2.5 to 3mm
Click to expand...
i just made a new tip. stahl discontinued everything at the same time for my unit(s) .. chisel tips are scarce around here but i've got plenty of other tips to file into shape. i had tried that before on a different unit and the tip would never tin again but the stahls do. yay. i've got enough extra tips to file into shape for many many years.
 
For me desoldering involves a plan. I don't ever just whip out the 808, or braid or what ever. Especially if its a hard to replace board or a particularly delicate board. Best thing to do is make sure you have a reason to remove what you are removing. It would suck to lift a pad removing a actual good part. So be as sure as you can in your hypothesis. Then plan it out, is a 2mm tip on a heavy ground plane a great idea? Most likely not. Some things don't need to come out to finish testing in that case just lift a leg and test. If im sure of my diagnosis or have a equivalent replacement part I will cut the leg if it will aid in sinking in less heat for less time.
 
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