Post by Jeff Ledger on May 16, 2008 10:27:50 GMT -5
I'm building a very nice parts box of electronics these days, thanks to the addition of a heat gun to my tool box. uC Hobby's original article raises some safety concerns in regard to lead fumes and lead poisoning and after a little research, I think I've found a safe way to do this and stay alive.
I have many boxes of boards with soldered in ICs and such. I sort of have an endless stream of them from various sources. I want to salvage as much as I can. I thought about using a heat gun, but was always wary of toxic fumes from overheated solder. I did try to use an embossing heat gun (from a craft store) which can get very hot, but obviously no hot enough to flash fire paper (450F). All I ended up doing is softening the circuit board.
I don't have a suitable heat gun yet. And I suppose I could invest in a high quality respirator. I use a simple mask when cutting wood and ceiling tiles for home projects. It's not that I wouldn't have any other reason to use a quality respirator. Since many of the components I want to remove are standard DIP chips, I toyed with the idea of fabricating a bent u-shaped metal piece that can screw onto a high wattage soldering iron.
For the piece of metal, I would make it as long as the chip I intend to remove and bend it lengthwise into a U shaped channel. Think of a line of staples that you'd put in your staple gun as the intended shape. On a 45W soldering iron element, there should be enough heat traveling to the edges of the metal that I can rest it across all pins on the IC to be removed and it should be easy to take out.
I'll let you know how it works if I ever get a chance to make one. Does anybody know which metal (safe and common) conducts heat better than most?
Post by iamdenteddisk on May 20, 2008 18:30:24 GMT -5
there are lots of hazards from "recycleing circuit boards" lead exposure,inhalation of resin's and burnned plastics ,these are all known carsenogens"causes cancer",">>"aswell as impotence""<< not to mention running drills through fingers or simply pricking your fingers on exposed componant leads, there are also poisons used in some devices like the waxy stuff used to insulate wire wound oscilators,transformers This poisonous waxy goo should not be heated with a heat gun as it will melt and thin to a liquid state and run all over the circuit board "colorless" wich then if you get scratched by a exposed lead or just get it in a hangnail can cause bad things, when I was in school for electronics they explained these things as well as introduced us to a "rework station" and after intro ,stated dont use them, I ask you now to explain why? your best bet is to use a good set of tin snips or hammer&chisel not on the componants but the board itself useing a good "bull dog shear" is good advice your end product is a componant with just a small piece of solder trace from there I suggest a 30Watt Iron and I use a shop vac with its hose duct taped to a chair makeing sure the sponge filter is in there it will stop most resin and open a window ,also most worthwhile componants have tempurature limmits although you save alot of resistors and time with heat guns , alot of ic's ,transistors, oscilators, transformers -just wont work correctly agian and thats the stuff worth saveing in most cases nothin beats a solder wik, pump or a shop/keyboard vac and iron. you may also want to get the sillinoid's relay's servo/pwm motors gears found in cassett's"for hobby'ist" and none of these can take heat without being sink'd as they have coils wich have coatings too or plastic packages Now if you just want to collect scrap metal or resistors then just setup an old oven outside place boards in it upside down ,hi broil till componants and solder fall down into a pan placed in the botom "cheap rework station" or heatgun away. but I once sold a large diode for $100 not a bad deal and well worth desoldering .
Post by iamdenteddisk on May 20, 2008 18:50:57 GMT -5
oh,p.s. a fan in the window close to work bench is good and standard tools safe but time consumeing wich is ok if you only do a little salvage --and if you do alot refer to my last post I feel it is a refined method, I do alot of salvage for my projects and some online sales too. im now wanting to devize a way to grind/pulverize ic's that I dont sale as some have precious metals wich can be refined for cash . imagine whats actualy in those landfills....
Post by Jeff Ledger on May 20, 2008 19:18:03 GMT -5
Actually I've had very good luck with the caps and crystals I've pulled in this manner. I've yet to find something that didn't work. Granted, I'm not really interested in the silicon. The one thing that I've really cashed in on with this is the connectors. Not having to purchase vga,serial,ps2,etc connectors for my projects has been wonderful!
"Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe." -Albert Einstein
There's good and bad reasons for salvaging electronic parts the "quick and easy" way using a heat gun. Everything in life is a carcinogen these days. Where does the line get drawn? You're probably exposed to more carcinogenic fumes filling the gas tank regularly than the occasional parts salvaging. I'll bet stuff I would buy at the Dollar Store exposes me to more lead than from solder.
The point is, to stay in the hobby involves a compromise. Especially if you want to be frugal. Ordering parts these days is about the only choice for people, like me, who don't live near one of the few remaining parts suppliers. Sure, I can walk into a Radio Shack and order nearly everything, without shipping charges, and wait over a week for it to come in. Mail order is cheaper, but you need to plan your orders in bulk to get a hedge on shipping charges. Some people don't feel like making large purchases to get what used to be the more common parts.
It comes down to the compromise of risk. Is it worth exposing yourself to a "potential" risk for a handful of parts? It depends on how much you believe the risk. We should all be growing our own organic food and live in natural log cabins based on the threat of carcinogen or other health risks stated in the world. Welcome to the modern world. I'd personally like to see the lab results from when the chemicals and elements were tested for health hazards. Is it dangerous for 1 in 100,000 or 1 in 10? Although I agree that lead and lead vapors are dangerous, I'll bet a majority of other dangerous chemicals were classified unhealthy by the state of California. That state would outlaw sneezing if it were considered a health hazard.
Don't get me wrong, it's unnatural to want to expose yourself to chemicals deliberately. In our hobby, we do it every time we use solder flux and rosin remover. That string of smoke from your soldering job spreads and fills the air rather quickly.
Personally, I'm not going to let good parts go to waste. Taking the extra effort to cut down a board to get to the parts might take longer than I care spend. Although, I never thought of that idea and it is a good suggestion for those that care to go that route. It has merit if you want to reduce bulk and salvage the final component as needed. I may try a few if I feel like spending extra time on a nice day, sitting on the back porch. Wouldn't there be a risk of cutting yourself from the ragged edge of a cut board? Why wouldn't I just wear a respirator and run the board through my scroll saw?
Meanwhile, heat and a respirator is a viable solution for me because I want to salvage and store my parts in their respective bins. I only do the salvaging work outside or in a ventilated garage (door open). The first time I tried it, it took about six minutes to remove over 30 chips in a "rank and file" configuration on an 8x10" board. I found a "sweet spot" distance of the heat gun near the board where the solder just melted and I wasn't burning the board. I then pop the part out with a small flatblade screwdriver. I can't heat and slam these boards because at least one pin on each chip was slightly bent over the hole. I used needle nosed pliers to yank the part out that didn't fly out with a screwdriver flick. As I moved slowly down the board, heat from the previous removal traveled to the next chip and before I knew it, I had a nice cadence going on the parts removal. I didn't smell any odd vapors in the respirator either. It's rated for lead and paint chemicals.