Introduction: Unsoldering Difficult Pcb Components.

Picture of Unsoldering Difficult Pcb Components.

So, you have extracted some components from an old circuit board, to be re-purposed at a later date.
It needed a big soldering iron and still some solder wouldn't melt to release a component.

The next step if you have some of that low melting point alloy is to try again using it to lower the melting point of the existing solder.

Or you could use a small flame to melt the solder and pull the (hot) components out.

Step 1: Make Sure the Flame Is Blue.

Picture of Make Sure the Flame Is Blue.

This is my favorite method, and I use a bent paper clip held in a vice to hook the component out as I lift the board and flame up and away. Sometimes I use a small spring to make the component pull out faster, and also have it drop into a bowl of water to cool quickly. The hottest part of the flame is at the tip of the pale-blue center cone. Ordinary cigarette lighters with a yellow flame are hopeless.

Be aware that burning fiberglass circuit boards emit smoke which smells vile and is probably poisonous, and makes clothing stink for ages.

And if the flame doesn't work...

Step 2: Hacksawed in Half. ("Don't Force It, Get a Bigger Hammer!")

Picture of Hacksawed in Half.   ("Don't Force It, Get a Bigger Hammer!")

For getting out a large bridge rectifier, I used a dremel to cut away the copper near the wires (wide copper tracks suck a lot of heat away). On another occasion where the rectifier was near the edge, I was able to use a hacksaw to thermally isolate the component.

Large components (Mosfets) mounted on the main power supply heatsink proved difficult until I realised that if I was willing to sacrifice a few components, I could hacksaw through the middle of the board to get access to the screws holding stuff to the heatsink.

The white silicone stuff used to stop vibration was easily cut with a knife. By the way, hacksaw blades get blunt quickly when used on fiberglass.

Comments

russ_hensel (author)2016-10-05

Just a note to let you know I have added this to the collection: Difficult Dis-assembly: Taking Things Apart for Repair

>> https://www.instructables.com/id/Difficult-Dis-ass...

There are a lot of things that are hard to take apart and lot of methods.

Caspar (author)russ_hensel2016-10-05

Thanks, Russ.

BeachsideHank (author)2016-10-04

I have drawers full of components I harvested that will probably go unused when I take my dirt nap.☺

Me too, so sad. Look to your will.

acheide (author)2016-10-05

Good idea for salvage. Thanks.

Swansong (author)2016-10-04

Thanks for sharing :)

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