Gold sputtering is a process for creating a very thin layer of gold on a surface. Sputtering is also available with other metals, and is most commonly seen in the electronics industry and the sciences. This technique requires a special device and controlled conditions for best results, along with discs of gold known as “targets” to provide a source of metal for deposition. Manufacturers produce sputtering equipment and private firms can perform this process by request.
In gold sputtering, the technician excites the atoms on the target, usually by bombarding them with energy. The target starts to eject atoms, and they land on a substrate. People may coat circuit panels, metals, and other objects using this process. The layer of gold will be very even and also very fine. The technician can control where and how the metal deposits, creating custom patterns to meet specific needs. Technicians can also use sputter etching, where the target releases etching material to lift parts of a coating.
For processes like scanning electron microscopy, scientists use gold sputtering to prepare specimens so they will be visible under the microscope. Circuit boards may require fine layers of gold on specific areas, and other electronics components may require similar treatment. This metal has a number of properties of interest, including good conductivity, making it a very suitable metal coating. Sputter deposition can also be used for activities like adding film to window glass for energy efficiency.
People use very pure sources for gold sputtering, and can order targets from manufacturers or prepare them by hand. Technicians usually use a clean room for the process because they want to avoid impurities in the gold. Any problems with the deposition can make an item useless, and impurities may not be readily apparent because they often occur on a microscopic level. Something like a fleck of dust, for example, could skew the readings on a scanning electron microscope and force the scientist to start all over again.
This process differs from gilding and other methods people use to apply decorative metal coatings. Jewelers may employ gold coatings on cores of other metals to lower production costs or get the look of gold and the strength of a different metal. They do not use gold sputtering technology and the tolerances in terms of impurities are much higher, with a focus on visual defects rather than issues so small that they can only be seen on a very high powered microscope.