Why is it so hard to desolder iMac capacitors?

These capacitors are challenging to replace because Apple is using lead-free solder to comply with RoHS. Lead-free solder melts at a much higher temperature.

"The main problem(s) with desoldering electrolytic capacitors from an iMac motherboard (or any logic board) is due to lack of soldering skills and/or knowledge of soldering - possibly too low of wattage soldering iron. But, I do it on a regular basis with a 40 watt iron - though ""the authorities"" claim you need a 60 watt stain glass iron for the job.

Kyle correctly pointed out that lead-free solder to comply with RoHS. Lead-free solder melts at a much higher temperature. He over looked that if you melt some lower temp solder into the existing joint that this factor goes away.

BAC correctly points out that this is a thick, multilayer board and it acts like a heatsink. Again, this factor becomes negligible if you melt some low temp solder into the joint.

I know it sounds crazy saying to desolder something that you need to add fresh solder to it- preferably with a lower melting point - to make the process of desoldering go faster and smooth, but the method is tried and true."

"I don't know the specific details of the logic board you're working with, but in general multi-layer circuit boards are often difficult to desolder components because the many copper layers within the board can too easily conduct the heat away from the area you're trying to heat, especially if you're using a low wattage soldering iron. in any case you need to be careful about overheating the board and possibly delaminating nearby traces.

are you using a solder-sucker or solder wick in addition to heating with an iron? those may help"

"Are you heating the wick, then the lead?

N."

You can try just pulling the Capacitor off, leaving the attaching legs/wires, then solder the new capacitors to the remaining wire. This requires no soldering directly on the motherboard.

"Radio-Shack have a very nice iron with a hole in the tip; I found this makes working on the G5 iMac board much easier, as it heats all round the lead.

http://www.radioshack.com/product/index....

I recently re-capped a G5 iMac board, and it went very smoothly thanks to this $12 iron.

Replacing the capacitors can be done without having to clear the holes, by cutting the leads short so they can be pushed in with a little pressure as one heats from the other side."