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desoldering pcb tips

Desoldering lead free + tiny holes + tiny traces + double sided PCBs is a nightmare without proper tools.

Many times I end soldering on the remaining solder, from the components side, trying to melt the solder with the capacitor lead at the same time I try to insert it in the PCB. No way to clean the old solder.
 
elnaldo said:
Desoldering lead free + tiny holes + tiny traces + double sided PCBs is a nightmare without proper tools.

Many times I end soldering on the remaining solder, from the components side, trying to melt the solder with the capacitor lead at the same time I try to insert it in the PCB. No way to clean the old solder.
Click to expand...

that is a cool trick!

the stuff I'm working on is pretty old - would that approach work for old pcbs? snip the lead of the cap on the component side, heat the lead and push the new cap through?

Thanks!
R
 
rmunson said:
that is a cool trick!

the stuff I'm working on is pretty old - would that approach work for old pcbs? snip the lead of the cap on the component side, heat the lead and push the new cap through?

Thanks!
R
Click to expand...
Old solder melts easier and the PCB holes are larger. What I do in old PCBs is to melt the solder and open the hole with a toothpick.

Pushing from component side could lift a pcb trace.
 
I've used the solder sucker and wick. It takes me a long time to desolder a component and I fear that I'm putting to much heat on the board and components. I'm in the process of troubleshooting a power supply on a sub. I have a lot of desoldering to pull components from the board to check values of components. I put the project on hold and ordered the FR-300. It should be arriving today.:banana:
 
nackesww said:
I've used the solder sucker and wick. It takes me a long time to desolder a component and I fear that I'm putting to much heat on the board and components. I'm in the process of troubleshooting a power supply on a sub. I have a lot of desoldering to pull components from the board to check values of components. I put the project on hold and ordered the FR-300. It should be arriving today.:banana:
Click to expand...
I think you will love it. For those components where the leg is bent 90 degrees under the board, just GENTLY wiggle the component while you suck the solder out. When you remove the gun, continue gently wiggling for 2-3 seconds until the solder hardens. This keeps those legs from reattaching. Then you can take a hemostat or small screwdriver and straighten the legs - or just clip them off at the board - before lifting the component off. Of course, if you get the sense that the leg did reattach as the solder cooled, immediately stop wiggling and reheat. Also, there is a rigid wire used to clean the bore of the sucker while it is hot to keep it open. Watch for the sucking to be less effective and clean it out with the wire and use the wire every time you finish a session before turning the unit off. Good luck with it!
Steve
 
Steven Tate said:
I think you will love it. For those components where the leg is bent 90 degrees under the board, just GENTLY wiggle the component while you suck the solder out. When you remove the gun, continue gently wiggling for 2-3 seconds until the solder hardens. This keeps those legs from reattaching. Then you can take a hemostat or small screwdriver and straighten the legs - or just clip them off at the board - before lifting the component off. Of course, if you get the sense that the leg did reattach as the solder cooled, immediately stop wiggling and reheat. Also, there is a rigid wire used to clean the bore of the sucker while it is hot to keep it open. Watch for the sucking to be less effective and clean it out with the wire and use the wire every time you finish a session before turning the unit off. Good luck with it!
Steve
Click to expand...
+1 I do this as well. Moving the component being removed keeps the solder from re-adhering.

As far as keeping the gun clean, after you've owned one for a while you'll hear the pitch change when it needs to be cleaned. Like a vacuum cleaner when you sucked up something that's plugged up the hose.
 
ok, I got a good feel for desoldering with the manual solder sucker method --

took some doing, but I found flux and solder wick today at hobby shop that has a lot of drones/remote control stuff
never thought I would miss Radio Shack --

interested to see if I get better results with the solder wick/flux method --
 
Solder wick and me are "becoming friends" little by little, and the manual solder sucker is being used less and less... At first, I didn't catch it, but with practice you start to understand how it works, and the results improve a lot. I just use the sucker in very old stuff, tube stuff, or to remove large caps where you need to remove a thick piece of solder. All the rest, small components, transistors, 24 pins ICs, and so, just the wick. I prefer to use more wick but do a faster job.

One trick I've learned, other tech told me to wet the wick with flux, but that was NOT needed, that was the reason I wasn't having good results. The dry wick, as you buy it, on a clean solder joint (sometimes adding fresh solder) woks perfect, and once hot, keep cleaning other components leads instead of cooling it and start again in other point. Also, cutting the end at 45º and using a sharp soldering iron tip allows to clean inside medium sized holes. Or, sometimes I add more solder (fill the hole again) so the wick sucks all again.

On dusty boards, clean with IPA first, have a clean PCB to desolder.

(BTW, cool collection of tips in this thread ! )
 
elnaldo said:
On dusty boards, clean with IPA first, have a clean PCB to desolder.
Click to expand...
good idea!

so I did a bit more practice on my dvd/vcr donor unit -- I learned from this practice technique that lead free modern stuff requires a lot more heat than the old tin/lead solder -- after a few last practice removals I was ready to perform the operation on my first patient - the 70s era mavnavox -

everything went very well -- the old solder flowed with no problem, the pcb didn't seem to get overheated. I used the heat and squeek method, where one one contact is heated to the point of melting the solder and I gently pulled the capacitor and it came a fraction of the way out with a little squeek - basically walking the capacitor out by gently pulling one side, "squeek" then over to the other side, "squeek" - back and forth on each lead until the capacitor is out --

Do this maybe 5 times on each lead and the capacitor is almost out -- here the solder sucker worked nicely to just remove enough solder and open up the terminal hole --

If one of the solder points did not want to melt, I just gave them a little encouragement with a little bit more solder to pep the point up -- with the new solder the process moved forward normally -

solder sucker was optional - maybe used it 25% of the time - most of the capacitors came out with just heat and squeek and gentle pulling pressure -

I found that the flux and solder wick was not really needed -- Had I used solder wick, I think I might have applied too much heat, because the process seems to take more heat and surface contact time --

One thing I like about the heat and squeek method is your left hand is touching the component that is being desoldered, so you know when you're applying too much heat --

Thanks guys for all the tips and guidance on the desoldering process! I'm glad I got advice and practiced before jumping in
 
One thing I do sometimes is to put a dot of solder on the tip of the iron, will transfer the heat to the board almost instantly. If testing and reusing it really helps when using a heat sink on the component leads. For those bent leads I use two irons, one with a small flat tip to bend the lead. Quicker is better I think.
 
Huge fan of braid. In general I find no single technique works when you depopulate a board so you need alternatives -

wick.jpg
 
Bob said:
flux is like cooking in a frying pan without oil. the flux melts and transfers heat
to assist the solder/unsolder process.

it is always a good idea to add flux to a joint you wish to unsolder.

even the (de)soldering braids have flux.
Click to expand...
Wrong, flux cleans the solder joint and prevents oxidation. Oxidation can prevent effective transfer of heat and the chemical bond of solder to copper.
 
I prefer to use desoldering braid. It removes solder more completely than a solder sucker (except the Hakko tool) and there is less chance of tearing the pads on the board.
 
its whatever works for you . i prefer my solder sucker over braid . haven't tried a de-soldering iron yet . have tried braid a few times .maybe my iron isnt enough wattage to keep up with the braid . or the tip is too small .
 
wrong? wow

I usually clean LPs, and solder joints with alcohol. so I don't need flux?

I find flux helps me with soldering braid (even with its built-in flux) , I notice
it melts quickly (doh!) and the braid takes over quicker. in fact I don't use braid
without flux.

so no need for flux if the conformal coating is removed (with the proper chemical)
and if the joint is cleaned with say alcohol (I always do this) then there's no
further need to clean and flux is superfluous.

learn something new every day.

I do love your guide to fixing CDPs and recommend it every time I see a need
for it. and thanks for your contributions to AK.
 
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