Frequently Asked Questions

The power requirement table, found in our Technical Library, is a current-driven reference table based on experimental values from testing only the evaporation source. As a thermal evaporation guide, it provides information about estimated amperages needed for the thermal evaporation source to reach the specified temperature.

These values are not a maximum rated temperature. Keep in mind that results may vary depending on your vacuum chamber set-up. Furthermore, the thermal output is changed by adjusting the amperage by the same percentage as the temperature.

Aluminum can be successfully thermally evaporated with several sources including a filament, boat or crucible. However, the correct source for your needs depends on the power you have available from your transformer, the volume of aluminum to evaporate, and the distance from your source to the substrate. Generally, a tungsten filament or boat will work very well for most evaporations.

Yes. A “Chrome Plated Tungsten Rod” is a simple and user-friendly way to deposit thin layers of chrome. These rod sources provide good thermal efficiency, regulation of film thickness and elimination of spalling. To add on, page 37 of our catalog shows more information.

Your best choice would be to use a tungsten filament or basket.

Although nickel has a much higher melting point than aluminum, many tungsten filament and basket configurations are capable of reaching high enough temperatures for both materials. However, the materials mentioned are somewhat corrosive when melted, with nickel being the most corrosive. This will lead to the eventual deterioration of the filament or basket.

Another alternative would be to use a tungsten basket heater with the appropriate crucible. Although this will require slightly more power, deterioration will be minimized and both the basket and crucible will provide several uses.

Our sources are designed to be used at high temperatures within a vacuum chamber. Depending on how rigorous your vacuum conditions are or how extensively you are using these sources, they will inevitably wear out.

If your evaporation source is failing under a short period, another question to ask would be “Is the material I am trying to evaporate corrosive?” Some examples of corrosive materials include aluminum and nickel, to name a few. However, we can help you choose a source that will best resist corrosion for your application.

SiO tends to “spitting and streaming” during evaporation, resulting in pinhole-type defects in most coating applications. One way to reduce the particulates in your vapor stream is to use a “multi-baffled box source”.

This type of source positions your evaporant material in two separate cavities. When heated, it follows an indirect path through a series of baffles and then out the vertical chimney. In other words, your substrate cannot see the bulk material at any time. Essentially, this eliminates any chance of spitting and streaming that causes pinhole-type defects.

You can find this type of source pictured, with various configurations, on pages 31 through 34 of our catalog. For more info, see our thermal evaporation guide resources relating to SiO, which are available to you by clicking here or here.

One solution is to use an alumina coated boat source.

In this type of source, alumina is plasma-coated onto the evaporation boat. This acts as an inert surface and prevents the gold from wetting to it. Also, when the gold melts it forms a sphere resulting in point source performance. Because of this, this style gives a long life compared to uncoated sources. Pages 23 through 27 of the catalog pictures a variety of our alumina coated sources.

Another recommendation is to consider using a crucible and crucible heater to hold and heat your material. Crucibles also provide a focused evaporation pattern and are available in several ceramic and metallic configurations.