For the past couple of hours I've been trying to get the solder out of a hole. It's a mobo cap, and the other hole sucked right out. It's like an obstruction. The solder melts with difficulty, but even then I can't get a dental pick as deep as in the other hole. The cap pulled out easily on both leads.
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Probably a multilayer board with a big ground plane acting as a heat sink.
Find some compressed air and a cardboard box. Get the solder melted with a soldering iron. Use flux. Point the back side of the PCB towards the cardboard box. Heat the back side of the PCB with the soldering iron. Apply the compressed air nozzle to the circuit side. Remove the soldering iron and very quickly blow some compressed air through the hold. The dross should land inside the cardboard box.
Also, pointed dental picks don't work well because there's too much room for the solder in the hole with the tapered tip. Use a paper clip or stainless piece of wire instead.
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Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
burned up and oxidized tips and traces don't conduct heat well and won't melt solder in a thick or multilayer board. get some solder wick, the stuff is magic for things like this.
For the past couple of hours I've been trying to get the solder out of a hole. It's a mobo cap, and the other hole sucked right out. It's like an obstruction. The solder melts with difficulty, but even then I can't get a dental pick as deep as in the other hole. The cap pulled out easily on both leads.
***Start by flowing in some 60/40 - at least if you can attack it at a lower temperature, it'll take longer to cook the copper/pcb bond.
***If you're using a solder sucker, putting the nozzle off center on the hole can sometimes draw molten solder out the top of a blocked hole - you need to do both sides before attacking the blockage.
***Resist the temptation to force a pin through while heating the solder - almost always takes the through plating with it.
A Solder Sucker is much better than a dental pick (I've used both). The solder sucker can be used on one side of the board while the iron is still on the pad on the other side of the board, which is when the solder is at its most liquid state.
Thanks. Y'er right. Goggles or a face mask are a must.
Back in the days when it was worth the effort, I used to remove components from a PCB by clamping one end of the board in a bench vise and heating the solder side with a propane torch. When the solder was good and hot, I would pull the board back and let go. The components and the solder would go flying in the opposite direction into a cardboard box. I always wore a face mask, but still managed to burn myself in obscure places.
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Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Depending on where you live, it's probably illegal. But you'd never be prosecuted, because nobody would know... unless you blabbed it to a few hundred million people on the internet. ;-)
Thanks. Y'er right. Goggles or a face mask are a must.
Back in the days when it was worth the effort, I used to remove components from a PCB by clamping one end of the board in a bench vise and heating the solder side with a propane torch. When the solder was good and hot, I would pull the board back and let go. The components and the solder would go flying in the opposite direction into a cardboard box.
***Hot air (electric paint stripper) gun and a stiff paintbush - perfect for harvesting SMD parts.
I got it by applying an iron to one side and the vacuum to the other side. The Pace desolder station doesn't get hot enough.
I was also using lead-free when I added solder to help it melt. 60/40 worked better.
What's the word on using 60/40 on the replacement?
***Original manufacturers have made remarkable progress in applying RoHS solder so the components don't fall off after a year or so - unreliability can rear its ugly head if you pb free solder with the kit on a typical repair bench.
***If you do get called to book for using 60/40 - just claim that its old equipment, and you believed that's what it was originally made with.
***If its for hobby purposes and not for resale, that's also exempt.
If you have some indium base solder or old leaded solder, reflow it with that, then suck it out..
***Way back in the days of hybrid CTVs, I remember an old Tandberg telly that had a "safety pin" style thermal fuse connecting the top cap of the horizontal sweep tube, just inside the timebase cage was a clip holding a small roll of low temperature cadmium solder (and a warning label not to use
60/40) for resetting the fuse.
***No doubt the Brussels suits reaction to lead solder would pale into insignificance compared to cadmium solder!
Yep, but I don't do it that way. With SMD, the problem is identifying the parts after they've been removed. I usually just want the active components anyway. So, I have a hot air desoldering station to remove the chips individually with the help of some liquid flux. The parts are then bagged and labeled in paper coin bags. A mess of random SMT components does me no good when I have to spend hours trying to identify or find a specific component.
Overall, the small parts are so cheap, that I'm questioning whether it's even worth salvaging the parts. Certainly for RAM, uP, and possibly BGA chips. However, it's usually easier, cheaper, and takes less time to just order the parts from a distributor. Also, I suspect that I only use maybe 1 part for every 100 parts that I scrap. Recently, I've gone back to just storing the PCB's, and pulling off parts as needed.
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Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
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