Using a paint stripper heat gun to de-solder?

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Lardo Boffin
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Using a paint stripper heat gun to de-solder?

Post by Lardo Boffin » Sat Oct 27, 2018 4:24 pm

I’m fairly certain I didn’t imagine reading that someone on here used a paint stripper heat gun to desolder chips?
Having finally finished unboxing my garage I have just found mine and have a potential use for it.
I have just taken delivery of a DOA issue 3 zeddy which doesn’t look to be socketed so chances are I will need to remove chips. This is not something I have done before very successfully with a normal de solder sucker.
I was wondering if this would be less damaging? Assuming I actually read it...
I presume you heat up the solder on all legs and then pull the chip out leaving most of the solder behind which you then remove as normal? Do you put any kind of heat resistant stuff, e.g. silver foil around the rest of the motherboard while concentrating on the chip?
Is it trial and error holding the heat gun at the right distance from the pcb or is there a generally good distance to use?
Any other advice, including ‘don’t do it!’ appreciated!
Thanks
Lardo
ZX81 iss 1 (bugged ROM, kludge fix, normal)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

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1024MAK
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Re: Using a paint stripper heat gun to de-solder?

Post by 1024MAK » Sat Oct 27, 2018 5:54 pm

What! Mo? Use a paint stripper on a PCB? :shock:

Well, just maybe...

Yeah, using an electric paint stripper is not an exact science. You can shield parts you don’t want to affect. You also want to use the small nozzle. I normally support the PCB in a vertical position. Then heat the solder pads of the chip, moving along each row. Keep moving, don’t stop in one place. The idea is to evenly heat up all the pins, but not too fast. If you linger in one place, or are too slow, you risk burning the PCB. If the paint stripper has a heat or temperature control, you will have to determine which setting works best. Start off with the low or medium setting/level. The distance depends on the size of the nozzle and the air temperature of the air from the paint stripper. But don’t get too close. While too far away means you may take forever to heat up the solder. If you carefully watch the solder, you may see the joints change shape as they melt.

On the other side, I use a pair of very long dentists tongs to hold the chip at the ends. So that when all the solder on all of the pins has got hot and melted, I can simply and gently pull it out with hardly any force.

If you are going to try this, I strongly recommend you practice on a board that you don’t mind damaging.

And yes, clearing the solder from the holes is done with a solder sucker afterwards.

Also, this is a lot kinder to the board if you do this in a warm room.

Removing DIL chips this way should not damage them.

If you do try this, please do feedback how you got on.

Mark

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mhudson52
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Re: Using a paint stripper heat gun to de-solder?

Post by mhudson52 » Tue Oct 30, 2018 1:16 am

I have a PCB that I somehow managed to solder the chip sockets to the wrong side of the board (old age is unkind at times).
After considering using a solder sucker, heat gun, etc. to free them from the board I am going try something a little different.

I bought a 1x1x2 block of copper that matches the pins of the sockets. The plan is to use a propane torch to get copper block good and toasty so that when the pins are set on it, it will melt the solder on all the pins of the socket at once thus allowing the socket to be lifted from the PCB. If successful all that should be needed afterward is a little cleanup with the soldering iron and copper braid.

Of course,a little trial and error may be required to perfect the technique. :o

I'll report back on my results.

Mike
TS 1000 bought in 1982 and brought back to life by Sir Ian

Lardo Boffin
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Re: Using a paint stripper heat gun to de-solder?

Post by Lardo Boffin » Tue Oct 30, 2018 1:21 pm

I tried the paint stripper but stopped. The board was starting to give off smoke and the solder showed no signs of melting.
It was at this stage I decided that I would not easily be able to explain how and why I burned the garage down to Mrs Boffin or the neighbours (shared garage type of thing) and so stopped. :shock:
ZX81 iss 1 (bugged ROM, kludge fix, normal)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

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1024MAK
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Re: Using a paint stripper heat gun to de-solder?

Post by 1024MAK » Tue Oct 30, 2018 1:28 pm

The old flux will burn off, even if a soldering iron is used... But with hot air, greater amounts will burn off, as more of it is getting hot!

The only other things that may burn if they get too hot are the screen printing (if any), solder resist or the board itself. This assumes that you are working on the non-component side.

As with all these things, it sounds a lot easier than it is in practice. But trying to accurately describe the process is harder than doing it!

Mark

Lardo Boffin
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Re: Using a paint stripper heat gun to de-solder?

Post by Lardo Boffin » Tue Oct 30, 2018 2:34 pm

So, be brave and have a bucket of sand ready! :lol:
ZX81 iss 1 (bugged ROM, kludge fix, normal)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

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1024MAK
Posts: 2121
Joined: Mon Sep 26, 2011 10:56 am
Location: Looking forward to summer in Somerset, UK...

Re: Using a paint stripper heat gun to de-solder?

Post by 1024MAK » Tue Oct 30, 2018 3:23 pm

Lardo Boffin wrote:
Tue Oct 30, 2018 2:34 pm
So, be brave and have a bucket of sand ready! :lol:
And water!

And did I mention to practice on an old unwanted PCB first?....

If you are not sure if the solder is melting, poke it with a screwdriver...

You can always clean the old flux off first with IPA ;-) Just make sure all the IPA has dried before using the hot air!

Mark

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mhudson52
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Re: Using a paint stripper heat gun to de-solder?

Post by mhudson52 » Thu Nov 01, 2018 6:58 pm

Update. My efforts to heat a copper block to melt the solder on socket pins was a total failure. Even after heating the block for several minutes with a propane torch it never got hot enough to melt solder. Would apparently need a furnace to get it hot enough.

One scrapped PCB.

Mike
TS 1000 bought in 1982 and brought back to life by Sir Ian

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