Soldering tip of the day

R.G. · February 23, 2009, 07:00:57 PM

Solder is metal - and heavy. When it's liquid, it has a lot of self-cohesion and surface tension, so it holes up in little crevices - like PCB holes - and refuses to flow out unless forced.

But heavy also implies lots of mass per unit, and that implies lots of momentum. If you are holding a PCB about two inches above your work table and melt the solder in the hole, then -*whack*- the board down sharply on the table surface, the liquid solder's momentum keeps it moving when the PCB stops and the ...solder...drops...out...of...the...hole... into a little splat on the table. Clean hole. It's hard to believe how easy it is until you've done it.

mth5044 · February 23, 2009, 07:08:07 PM

Sounds cheaper then desoldering braids

Although I'd want to hide behind solderproof glass before atempting it

petemoore · February 23, 2009, 07:52:04 PM

Surprizing to hear RG type of such a thing.
One super quick clean method of clearing solder off though.
A really good stiff breath takes solder off of potlugs.
As long as you get a good straight swak away from the board...you don't get side splatters, They usually can be picked off because they don't really heat the surface they cling to, don't ask how I know this.

frank_p · February 23, 2009, 08:19:21 PM

Hmmm... Not a bad idea... A heated centrifuge machine, put all your junk PCB in it. And spin that wheel... Parts and solder for free !
Ehm... Is there a patent already for that ?

R.G. · February 23, 2009, 08:42:13 PM

Quote from: petemoore on February 23, 2009, 07:52:04 PM
Surprizing to hear RG type of such a thing.
One super quick clean method of clearing solder off though.
A really good stiff breath takes solder off of potlugs.
Quote
EEK!! You would BLOW molten solder off lugs? ARGHH!!! To do any good your eyes must be within inches of the solder.

Quote
As long as you get a good straight swak away from the board...you don't get side splatters, They usually can be picked off because they don't really heat the surface they cling to, don't ask how I know this.
On most surfaces, the solder cools semi-instantly and does not splash. There's not all that much solder there in a PCB hole, anyway. It's especially good for plated through holes.

petemoore · February 23, 2009, 09:16:21 PM

You would BLOW molten solder off lugs? ARGHH!!! To do any good your eyes must be within inches of the solder.
Sure..I got lucky, with a good blow the solder seems to pattern away like a shotgun, plus I should have mentioned I wear glasses, I think I forgot to mention try this at your own risk and only with approved safety glasses.

Zedmin_fx · February 23, 2009, 10:15:40 PM

Hey yea thats what I have been dooing with stomp switches, man its easy and cheap very good tip.

chi_boy · February 23, 2009, 10:29:33 PM

Does anyone else use one of these? I use mine regularly and love it. It makes removing most things a snap. Even IC's.

reverbie · February 23, 2009, 10:49:16 PM

Sorry, I have to advise against molten metal being ejected in an uncontrolled manner. Anyone who has ever had solder splashed in their eyes would think twice about this ( I have). What a better option would be is to desolder from underneath with a braid with some flux on it or with the board perpendicular to your surface (which i do only the newer through hole plated dual sided PCBS with much success).

frank_p · February 23, 2009, 11:13:05 PM

Quote from: reverbie on February 23, 2009, 10:49:16 PM
( I have).

Ouch ! Hope you still have both eyes...

StereoKills · February 23, 2009, 11:25:55 PM

I use one of these, works pretty well.

Cliff Schecht · February 23, 2009, 11:38:01 PM

Quote from: R.G. on February 23, 2009, 07:00:57 PM
Solder is metal - and heavy. When it's liquid, it has a lot of self-cohesion and surface tension, so it holes up in little crevices - like PCB holes - and refuses to flow out unless forced.

But heavy also implies lots of mass per unit, and that implies lots of momentum. If you are holding a PCB about two inches above your work table and melt the solder in the hole, then -*whack*- the board down sharply on the table surface, the liquid solder's momentum keeps it moving when the PCB stops and the ...solder...drops...out...of...the...hole... into a little splat on the table. Clean hole. It's hard to believe how easy it is until you've done it.

I give a soldering tutorial every semester for IEEE and make a point to teach fresh students this exact technique, as well as solder braid and desoldering pumps. It works equally well for SMD's if you've got room to splat around a little bit of solder (usually it comes off of the board with a fingernail anyways), but can also throw solder bridges everywhere if you smack your board in the wrong direction. Hitting the board nearly parallel to the surface of smackage will usually prevent any bridges from forming though.

Another good tip is to move the soldering braid around while you're using it. Just leaving it in one place doesn't really encourage the capillary action to take place, you've got to break the surface tension of the solder before it will flow nicely. If your solder braid is leaving a sticky mess of goo all over your board, then it's working its magic! Also, flux is good to use for crappy, oxidized old connectors.

There's a lot to cover on the topic of soldering, which is why it sucks trying to cram it all into an hour long info session!

petemoore · February 24, 2009, 08:20:37 AM

Pretty logical, but don't try it at home, unless you know what your'e doing with the safety glasses.

jefe · February 24, 2009, 08:29:21 AM

Quote from: petemoore on February 24, 2009, 08:20:37 AM

Pretty logical, but don't try it at home, unless you know what your'e doing with the safety glasses.

Safety glasses were my first thought as well.

I'm pretty sure I've done this before... I seem to remember whacking a board on a table, or flicking wires to remove excess solder... I've definitely made little splatter puddles of solder, just can't remember why... lol...

drewl · February 24, 2009, 08:39:27 AM

Quote from: R.G. on February 23, 2009, 07:00:57 PM
Solder is metal - and heavy. When it's liquid, it has a lot of self-cohesion and surface tension, so it holes up in little crevices - like PCB holes - and refuses to flow out unless forced.

But heavy also implies lots of mass per unit, and that implies lots of momentum. If you are holding a PCB about two inches above your work table and melt the solder in the hole, then -*whack*- the board down sharply on the table surface, the liquid solder's momentum keeps it moving when the PCB stops and the ...solder...drops...out...of...the...hole... into a little splat on the table. Clean hole. It's hard to believe how easy it is until you've done it.

Ha, I had a teacher show us this once...WHAM! he slammed the board on the table and it broke!
great tip, I prolly do it several times a day!

Boogdish · February 24, 2009, 09:11:56 AM

I thought this thread would just be a picture of the tip of a soldering iron with a little paragraph like: The weller size 2 chisel tip, dependable, sturdy, it's our TIP OF THE DAY. And then every day a new tip would be added.

Paul Marossy · February 24, 2009, 10:05:25 AM

I always watch for it (the solder) solidifying. You can actually see it doing this on bigger solder connections, like on a wire on the lug of a 1/4" jack. If I don't watch it and blow on it gently until its solidified, that wire wants to pull right out of there and then I have to do it again. Sometimes it can be a few seconds before it solidifies.

Ice-9 · February 24, 2009, 11:04:49 AM

I've used the melt and shake method for years, yes it can be dangerous but when you get used to it it's very easy and any splashes that do solidify usually just come off with a finger nail.

Quote from: Paul Marossy on February 24, 2009, 10:05:25 AM
I always watch for it (the solder) solidifying. You can actually see it doing this on bigger solder connections, like on a wire on the lug of a 1/4" jack. If I don't watch it and blow on it gently until its solidified, that wire wants to pull right out of there and then I have to do it again. Sometimes it can be a few seconds before it solidifies.

I was under the impression you should not blow on solder to solidify it quickly as this can cause dry joints or brittle joints.

MarcoMike · February 24, 2009, 11:33:41 AM

I've always done the "melt'n'drop" procedure RG pointed out... also for excesses of solder or joined traces... everytime thinking "good electro-gurus wouldn't apporve..." but now I know they do!!! supercool!!

MikeH · February 24, 2009, 12:18:09 PM

Quote from: Ice-9 on February 24, 2009, 11:04:49 AM
I was under the impression you should not blow on solder to solidify it quickly as this can cause dry joints or brittle joints.

I don't think you are- but I ALWAYS do it! It's like some ocd behavior I cannot shake. I don't understand it.

And I've used the "melt and drop" technique out of frustration before, when the tip on my desoldering iron is crappy and doesn't work well anymore. Once the tip gets worn and crappy it won't make a good connection and you can't get it to melt jack. I guess now that it's an endorsed technique I don't have to feel like a hack when I use it!

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Soldering tip of the day