Torching Circuit Boards and Harvesting Capacitors

[zpyder]

So I took some advice from members of this forum to harvest a bunch of components off of old circuit boards using a shop torch.  I would like to report that taking a torch to a circuit board to remove and harvest components like capacitors and resistors (file this sentence under SEO) works very very well... a step-by-step for anyone who would like to try this:

Firstly - SAFETY: DO NOT do this without safety gogles - the wrap-around kind.  Solder will fly, and if you f up, electro caps will blow up as well.  DO NOT do this without AT LEAST a wet cloth over your mouth and nose, prefferably, use a respirator.  I will report that using a wet cloth has left me with a very unfavorable taste in my face, as well as an odd sorish sensation in my throat.  I blame this on my initial failure at preventing the board from burning.    Do this OUTSIDE or at least in a WELL ventilated workshop.  Blow a box fan over your work area also.  If you burn the board at all, that smoke is toxxxxxxic and nassssty and sticks to everything.

1) Take your circuit board to be harvested, and either set it over, or even better clamp it down over a METAL bucket full of WATER.
2) I used what I believe was either an acetylene or butane torch (blue canister, common shop torch fitting), I've heard propane torches work fine great too.  Fan over the back of the circuit board with the the torch while the board is facing down over the bucket of water.  I found that centralizing the flame a little over a region with your desired components is much better than trying to heat up the whole thing at once, but DON'T focus the flame on one spot without moving it around (until you figure out how to do this quickly and correctly).  As I've seen RG say, IF THE BOARD MELTS OR LIGHTS ON FIRE, you're too close/too hot.  The idea here is to heat the solder up to the point of melting, without burning the board.
3) Have a metal wrench/small hammer ready in your other hand.  You should be able to determine when the solder starts melting.  As soon as it does, give the back of the board a whack.  The components should fall out.  Repeat if necessary.
4) Especially if you burnt the board, wash your hands, take a shower, change your clothes.  Stinky stuff...

The three most important things, I would say, would be: Wear goggles and a respirator, and ventilate the work area.  Use a bucket of water.  Do NOT burn the board.  I found out the hard way that without a bucket of water, and especially if the board gets hot enough to burn, electrolytic caps are going to start exploding.  Although kinda nifty, I wouldn't recommend letting it happen more than a couple times!

Be forewarned, if you have neighbors/roommates/family members that either see or smell you doing this, their reactions may be less than affirmative.  Remind them that you are recycling...

Well, it's as easy as that.  I harvested a shit ton of electro caps, some sockets, resistors, LED's USB & serial jacks all from a few old unused computer boards (including one motherboard).  Now I have plenty of those 16v 100uF caps I was looking for earlier this week.

Safety first!,
zpyder

[MartyMart]

Man you're NUTZ !! 

[george]

Be forewarned, if you have neighbors/roommates/family members that either see or smell you doing this, their reactions may be less than affirmative.  Remind them that you are recycling...

yeah but it sounds like you may exceed atmospheric emission limits in some states ...

[Connoisseur of Distortion]

Be forewarned, if you have neighbors/roommates/family members that either see or smell you doing this, their reactions may be less than affirmative.  Remind them that you are recycling...

yeah but it sounds like you may exceed atmospheric emission limits in some states ...

DIY has been found to cause cancer in the state of California

[Somicide]

shit, everything has been known to cause cancer here. 

Innovative, never though to use a torch.  A heatgun, perhaps, since I have one, but never a torch.

[R.G.]

I always like to see people try things I suggest. I'm glad it worked for you.

It's easy and quick, and works especially well on boards that have not had their component leads clinched.

For boards where the leads have been bent on the solder side, you will have to clamp the board vertically, using the torch on the solder side with one hand and pulling on parts on the parts side with the other hand and a pair of pliers or IC-extractors.

Done properly, there is less heat stress from this than from trying to desolder.

[markm]

Be forewarned, if you have neighbors/roommates/family members that either see or smell you doing this, their reactions may be less than affirmative.  Remind them that you are recycling...

yeah but it sounds like you may exceed atmospheric emission limits in some states ...

DIY has been found to cause cancer in the state of California

[Alex C]

For boards where the leads have been bent on the solder side, you will have to clamp the board vertically, using the torch on the solder side with one hand and pulling on parts on the parts side with the other hand and a pair of pliers or IC-extractors.

I use a heat gun and this is my method. After first clamping horizontally to remove the components that will come out easily, it's clamped upright and the remaining components are extracted with a hemostat or needle-nose pliers.

I don't have access to a torch, and I have liked the idea of a heat gun over a torch because I feel like I'm using "just enough" heat, but not too much.  However, it seems like "get in with high heat and get out" would apply here as well, so from that standpoint would a torch be a better choice in terms of minimizing heat stress/damage to components?

[Somicide]

That's a good question, Alex.  Anyone know offhand the melting point of solder?  something like ~650 Degrees (F)?  Or less?  I know my heatgun puts out some ~1400 Deg (F), and I'd imagine that's "high heat" enough

[zpyder]

I don't have access to a torch, and I have liked the idea of a heat gun over a torch because I feel like I'm using "just enough" heat, but not too much.  However, it seems like "get in with high heat and get out" would apply here as well, so from that standpoint would a torch be a better choice in terms of minimizing heat stress/damage to components?

Good question... from doing this tonight I would say that once you get the method down it could be quicker, and therefore be less likely to cause damage to components.  Keep in mind, though, that on the first board I torched I blew up about 3 electros.  This was due to me ineptly burning the board by getting too close to the board and focusing too much heat on one specific area.  It seems that since the metal solder is a much better conductor of heat than the circuit board material itself, that you can nimbly "fan" over a region of the back of the board and get solder that heats up quicker (and more evenly) than board.  Once the board begins to burn and flames are "pushing" your torch flame away from the board, concentrating heat on the solder leads becomes a messy and very smoky affair.  Don't let this happen... This was my first mistake.  Very toxic smelling shite.  Too little fanning and you get prolonged heat... not good for components.  After a few takes I was able to determine exactly when the solder melted.  It seems that the most efficiency I was able to get out of the burn was when I focused on about a 2-4 square-inch area, "fanning" over it rather than direct heat, saw the moment the solder melted, and immediately gave it a whack or two with my wrench.

Before I used the torch, I got out my soldering iron and pulled two electros out to see how quickly I could do it.  Not only was it more tedious since I had to use a pair of pliers even on un-bent leads, but I would have to say that my guy feeling tells me I was presenting quite a bit more heat risk to the component using the soldering iron method than I did once I got good at the torch method... The two leads were exposed to heat much longer when I had to heat them up independently with the tip of the iron...

It's easy and quick, and works especially well on boards that have not had their component leads clinched.

Yup, there was one electro on the motherboard I torched that had one bent-over lead.  This made it practically impossible to remove without using pliers.  I'd recommend only doing this on boards that have straight leads on the solder side of the board.

zpyder