Anyone who has soldered will be faced with the problem of removing a component. Everyone eventually makes a mistake. De-soldering requires 200% more skill than soldering. The reason for this is usually related to stress. The act of de-soldering a component is going to place an enormous amount of stress on the "land" which is also called the "pad" or "donut", and if it comes off the board, the whole project may have to be thrown out. The land is the copper pad on the printed circuit board. It is attached to the board by glue. This glue is very strong but when it is heated, the adhesion is reduced considerably. Every time it is heated and cooled, the strength of the glue also reduces. Replacing a component requires 3 cycles of heating and that's why the operation must be carried out very carefully. There is a whole range of tools and equipment to assist in the operation of de-soldering and the equipment you select will depend on a number of factors. De-soldering equipment ranges from $3 to $12,000 and these items would not be on the market if they were not needed. This simplest de-soldering item is Desolder wick. This is a length of copper braid that has been soaked in resin. Once a portion of it has been used, it must be cut off so that the end is clean and fresh. This is very important as one of the main purposes of the wick is to supply resin to the joint to allow the solder to flow from the joint and into the wick. Place the wick on the joint to be de-soldered and touch the iron on the top of the wick. You can turn the soldering station up 20C (50F) to increase the rate of heat transfer and overcome the heat-sinking effect of the braid. The solder will be drawn off the joint and run into the braid. You may have to repeat the operation on the other side of the joint. But this is the maximum you should do. The solder should be almost totally removed and the lead should be almost free. A slight sideways movement on the lead with a hot soldering iron will break or soften the last remaining attachment of the lead to the pad. Repeat with the other lead and the component can be removed. This is the ideal situation. Turn the soldering iron temperature down and it's ready to solder a new component. This is a fairly slow procedure and if you are faced with a large number of operations, you may prefer to invest in a de-soldering tool. There are two types of solder suckers. One is a hand-held syringe. It is used in conjunction with a temperature-controlled iron or standard iron. The iron is used to heat the solder on the connection and the tip of the syringe is placed over the lead of the component and pushed hard against the connection while, at the same time, releasing the spring-loaded plunger. The plunger works in reverse to normal operation. It sucks the solder into the body of the syringe. The other type of solder sucker is a soldering iron with a hollow tip. It will have a sucker bulb attached or a vacuum pump, to draw the hot solder from the connection. This type of solder sucker is more expensive but carries out the operation faster than the syringe as the tip is heated and can operate so quickly that the joint is hardly heated at all. This is because the hot solder is removed from the action.