What is UNCD?
Natural diamond has long been coveted for its extreme properties. In thin film form, however, capturing these properties reliably and economically has been in general a disappointment—until now.
Thin film diamond has graduated from the laboratory to become a genuine industrial material whose properties and performance characteristics can be characterized and reproduced. What is not widely understood is that the properties of these films can be tuned over a very broad range. Thus, like steel or aluminum alloys which are optimized for particular applications, so too can the properties of thin film diamond be adjusted in a controllable and reproducible manner.
UNCD® developed by ADT allows for the realization of many different types of diamond films that capture different subsets of properties of diamond, allowing ADT the unique ability to tailor UNCD for a broad range of applications. For instance, rough diamond films that have been available for years are extremely abrasive, and thus useful for cutting applications. However, UNCD allows for the roughness of the films to be controllably varied enabling films that are extremely smooth and exhibit very low friction yet retain the extreme wear resistance of natural diamond. In a similar manner the thermal conductivity, electrical conductivity, and optical properties can be varied over many orders of magnitude. Thus films that are highly electrically conducting at room temperature can have either high or low thermal conductivity and can also be made optically more or less transparent.
ADT’s UNCD Aqua Series™ is the first family of diamond thin films to be brought to the marketplace that spans a range of film properties that makes each one suitable to a particular application. All of the UNCD Aqua varieties are smooth enough to exhibit low friction in most applications, yet vary considerably in thermal conductivity, electrical conductivity, and optical transparency.
UNCD®, a form of nanocrystalline diamond, captures many of the best properties of natural diamond in a scalable thin film technology that enables diamond to be integrated into a wide range of products. UNCD is the term that encompasses a proprietary family of materials that are manufactured using patented chemical vapor deposition processes. UNCD can also have unique properties not found in any other carbon-based material that can be adjusted and optimized for a given application.
UNCD coatings are not diamond-like carbon films, but phase-pure crystalline materials consisting of ultra-small diamond grains ranging from 2-5 nm up to 1 micron in size depending on the variety of UNCD. Currently ADT offers the following subtypes of UNCD films:
UNCD Aqua™. The award-winning UNCD Aqua series of films developed by ADT are industrial-strength films that can be deposited on a wide range of materials including silicon wafers up to 300 mm in size and multiple 2D and 3D specimens simultaneously. UNCD Aqua is synthesized using certified processes that are the ultimate in repeatability and reliability. UNCD Aqua is optimized for demanding applications including MEMS,mechanical seals for pumps and biomedical devices, among others.
Mechanical and Tribological
- Extreme hardness.
- Extremely wear resistant.
- Extremely strong. Just as strong as single-crystal diamond.
- Smooth. Very low surface roughness.
- Thin. Ultrathin pinhole-free films can be produced.
- Excellent adhesion. UNCD is routinely deposited on silicon, SiO2, W, Mo, TiAl4V6, and alpha “self-sintered” (binderless) SiC as well as Ta and Si3N4. Materials that readily form carbides tend to make the best substrates. Please contact us to inquire about additional materials.
- Very low friction. Coefficients of friction as low as 0.03 in air.
- No stiction. Hydrophobicity eliminates stiction in MEMS components, reducing manufacturing and packaging costs, while enhancing reliability.
- Low film stress. Critically important for materials integration in MEMS and other thin film applications.
- Chemically stable and inert. Same surface chemistry as natural diamond.
- Hydrophobicity. Can be rendered either hydrophobic or hydrophilic by adjusting surface chemistry.
- Electrochemistry. Very wide working potential window, low background currents.
- Corrosion protection. Diamond surface chemistry and ultrathin continuous films provide protective coatings.
- Electrically conductive or insulating. High room temperature N-type and P-type conductivities have been demonstrated.
- Electron emitters. Low threshold, stable field electron emission has been demonstrated
- Surface functionalization. Probe molecules can be covalently attached with high stability for biosensors.
- Bio-inert. Can be used in biomedical applications such as bioMEMS sensors and implants.
- Low deposition temperatures capability. Compatible with fragile electronics and lower-melting point metals.
- Conformal coatings. Capable of coating high-aspect-ratio structures with conformal, smooth layers.
- Etching. UNCD can be etched using reactive ion etching.
For MEMS, UNCD enables devices to be fabricated that are:
- Faster. High acoustic velocity permits faster high frequency electronic filters and time references (MHz-GHz).
- More reliable. Low stiction, friction, thermal stability and superior wear resistance.
- Versatile. Can be deposited on a range of substrates and also integrated into complex thin film heterostructures. Can be used in harsh environments.