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 the estimated amperage needed 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.

Silver is one of the most user-friendly materials to evaporate. It behaves very nicely; it does not migrate  and it is not a corrosive material.

Our team typically recommends molybdenum or tantalum boats for evaporating silver. Specific boat selection depends on other factors like what space restraints your system has, how much capacity your thin film process requires as well as how much power you have to heat the source.

Please feel free to contact our technical team for help by filling out our evaporation source inquiry form.

A chrome plated tungsten rod is a simple and user-friendly way to deposit thin layers of chrome.

Compared to chrome chips, these rod sources provide good thermal efficiency, regulation of film thickness and elimination of spalling. To learn more, further information is found on page 37 of our catalog or our website.

Aluminum can be successfully thermally evaporated with several sources including filaments, boats and crucibles. However, the correct source for your needs depends on several factors, notably the power you have available from your transformer, the volume of aluminum to needed to evaporate, and the distance from your source to the substrate.

Generally, a tungsten filament or boat will work very well for most evaporations.

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

Even though 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 either a tungsten basket heater with the appropriate sized crucible or an alumina coated tungsten basket (RDM-WBAO Series). Although this will require slightly more power, deterioration will be minimized and both the basket and crucible will provide your evaporation process with several uses.

Alumina coated boat sources offer a couple of advantages over uncoated boats. These sources offer good thermal transfer, longer life, and inertness with most evaporants. We typically recommend alumina coated sources for when wetting and corrosion are an issue.

The alumina’s inert properties prevent wetting from occurring, eliminating losses due to wetting and resistance changes in the boat due to wetting moltent material. Notably, this type of source is ideal for the evaporation of gold. Materials that are corrosive when moltent like nickel, iron, and titanium will quickly corrode through the bottom of the boat and cause failure. An alumina coated boat prevents the corrosive material from touching the boat surface, extending boat’s life.

Alumina coating the inside of the boat prevents any losses due to wetting, which forms a sphere of evaporant that acts like a point source. Barrier-style alumina coatings allow wetting to the dimple area while preventing material from migrating out of the evaporation area, ideal for film applications where uniformity is needed.

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. Evaporation sources are considered consumable items.

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. Depending on the application, source lifetime can be extended with tungsten wire additives (see our WWMix), thicker boat material, or help with proper evaporation source selection.

Our micro-electronic sources represent a full line of smaller-sized sources that are similar to our standard evaporation sources. This includes a variety of different micro-electronic boats, filaments, crucible heaters and baffled boxes.

Micro-electronic sources are under two inches in length, enabling high temperatures needed for thermal evaporation with lower power requirements. These sources are also ideal for thin film coatings that require small amounts of evaporants.

SiO tends to cause 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 discuss evaporation techniques or the multi-baffled box source.

One recommendation is to use our alumina coated boat sources.

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