How to remove components from PCBs

[Curl]

I've been tearing some old PCBs up so I can build a nice collection of transistors and caps for myself, but the problem is I haven't figured out how I'm going to pull them off the PCB without cutting the legs off.

For some reason the solder is very strong and won't melt. I even took a propane blow torch to a PCB (for test) and the board caught on fire without melting the solder (the components melted too).

Is there a clever way of getting them off, or should I just use a Dremel to grind off the solder (is it even solder?) and pull them out?

 

[gnurf]

Yikes, a blow torch? Removing components from a PCB is normally done with a soldering iron (or, preferably, a temperature controlled solder station with a variety of tips) and some solder wick. Sometimes it helps to add new solder to help reflow the old solder, before removing everything with the solder wick.

Youtube tutorial:

 

[vk6kro]

You can use a hot air gun for this. It is surprising to see, but hot air can melt solder.

You may lose a few components, but circuit boards are a good source of valuable parts.

Be careful though. Hot air can cause a burn if it reaches your skin, even by deflecting off the circuit board.

 

[NascentOxygen]

For some reason the solder is very strong and won't melt. I even took a propane blow torch to a PCB (for test) and the board caught on fire without melting the solder (the components melted too).

Success is more assured when you use a heavier (i.e., higher power and greater mass) soldering iron for unsoldering than you would use for the soldering. Any oxide on the solder surface seems to act as a thermal insulator, inhibiting heat flow from the iron into the solder. A solder-sucker or a piece of solder wick is almost essential to clear the area and allow you to see how the original assembler has neatly folded at 90 degrees the legs of many components so they make good contact with their copper pads. You'll often have to free these and unbend them one by one before they can pass back out through their mounting holes.

My experience is that unsoldering jobs like this are best suited to someone with 3 hands.

Good luck! http://physicsforums.bernhardtmediall.netdna-cdn.com/images/icons/icon6.gif

 

[Windadct]

Also - many mass produced boards are ROHS - using higher temperature solders - even Silver based at times, can be hard to melt without the right equipment. Also a Digital soldering iron, with temperature set point is helpful, you can often tell how hard the iron is working to maintain the temp - allowing you to get a set up that works and have more consistent process, and less chance of cooking the components.