General Information
CVD diamond stands for Chemical Vapor Deposition diamond. The deposition of diamond is a highly complex synthesis process that uses carbon containing source materials together with other gas reactants to form a polycrystalline layer of diamond on a suitable substrate. After synthesis, the polycrystalline diamond film is removed from the substrate resulting in a free standing polycrystalline wafer with diameters up to 120 or even 160mm and a thickness of up to 2mm. The CVD diamond plate then can be cut to size and polished to the desired surface finish and flatness using proprietary technology. In many properties, CVD diamond is identical to natural diamond. Being a synthetic material, some properties of CVD diamond can be optimized for specific applications, depending on the synthesis process used.


 

Click image for larger view
Examples of two different grades of as grown CVD polycrystalline plates, the starting material from which DIAFILM polished plates are produced ( A transparent DIAFILM OP disc is shown on the lower right hand side).
 

 

 DIAFILM OP, for optical applications where diamond’s wide spectral transparency from the ultraviolet to the far infrared is required
 
  DIAFILM RF, for radio frequency applications that require a dielectric material having an extremely low dielectric loss
 
  DIAFILM TM, to exploit diamond’s unique thermal management capabilities

 

 DIAFILM PC, for precision mechanical cutting edge and wear component applications where high abrasion resistance combined with high fracture strength, stiffness and toughness are required.
 
To enable the appropriate selection of the DIAFILM material grade, a key properties Selector System based on typical application areas is given in the table below.
 

  DIAFILM is a registered trademark of Element 6

Return to top >
DIAFILM TM
The thermal conductivity of diamond is the highest among all known materials. At room temperature, it's thermal conductivity is a factor five higher than copper and over an order of magnitude more effective than commonly used "thermally conductive" insulators such as aluminium nitride and beryllium oxide. 
 

Click image for larger view
 
Due to its large band-gap and purity, diamond is and excellent electrical insulator. This property, combined with the high thermal conductivity, makes diamond an ideal packaging material for electronic and optoelectronic devices.
 
For these reasons, single crystal natural Type IIa diamond heat spreader have been used for the thermal management of microwave and laser diode devices for well over a decade. In these applications the size of the diamond is typically not more than one millimeter square, limiting the use of natural diamond to small discrete devices.
The availability of large CVD diamond plates showing similar thermal properties like Type IIa single crystal diamond, has opened a host of new possible applications in which diamond can be used in the heat management of electronic and optoelectronic devices. 

The increased control of the CVD syntheses process allows the manufacture of a range of DIAFILM materials optimized specifically for thermal management applications. The exceptional thermal diffusivity and conductivity of diamond both enhances the performance of the current products and allows new applications to be developed.

Click image for larger view
Temperature dependence of the thermal conductivity for optical and the three thermal grades for DIAFILM material in comparison to literature values of Type IIa single crystal diamond.
(Ref. IDR 2001/1/98)
 
The availability of optical and three different thermal grades of DIAFILM material provides a good compromise between quality, good thermal conductivity and cost.
 

Return to top >

 


DIAFILM OP
 
Diamond is considered to be transparent to the entire spectrum excepting a small intrinsic absorption between 2.5 and 10 microns. This optical property combined with the other extreme properties of diamond i.e. hardness, stiffness, wear resistance, radiation hardness, chemical inertness and low thermal expansion coefficient at room temperature makes diamond a unique component in many fields of modern optical technology. Type 2A single crystal diamond, the purest of all natural diamonds, is used in size limited optical applications. Careful selection and processing are required to create planar and hemispherical shapes. Typically these applications are for sizes less then 10.0 mm. The availability of large area DIAFILM OP allows for large area optical applications to be addressed. The optical properties of this material emulate those of natural type 2A diamond. Areas of application currently addressed range from on-line process control monitoring to advance laser based inspection systems. 

Click image for larger view
Transmission spectral range of diamond compared with other optical materials

 

Click image for larger view
UV-VIS transmission spectrum for a DIAFILM OP sample 1.0mm thick compared with that of a natural Type IIa single crystal window.
(Ref. IDR 2000/11/98)

 

Click image for larger view
An FTIR spectrum for DIAFILM OP
(Ref. IDR 4/200)
 


 

 

Click image for larger view

 
 

 

Return to top >
 

DIAFILM RF
 
DIAFILM RF was developed for Radio Frequency applications. It's extremely low dielectric loss coupled with it's high thermal conductivity makes it the ideal dielectric window material for very high powered Gyrotron tubes or microwave TWT windows. The tubes typically operate in the 70 to 170 GHz frequency region with output powers in excess of 1MW. For this application, window sizes up to100mm in diameter and a thickness of 1.6mm to 2.3mm depending on the microwave frequency are needed. These windows require relatively uniform dielectric loss over the area of the window to avoid hot spots. The absorption of radiation in low loss samples is usually measured as the decrease in the Q factor of a resonant cavity and expressed in terms of the tangent of a loss angle d. The figure below shows the dielectric loss profile of a 100mm diameter window with a thickness of 1.6mm. It can be seen that values of tan d below 10-5 are possible and that the material is uniform over the active aperture of the window.

 

   Click image for larger view
Profile of the dielectric loss measured at 145 GHz of a DIAFILM RF window 100mm in diameter and 1.6mm thick.
(Ref. IDR 2000/11/98)
 
The predicted temperature excursion for such a window for a 1.2 MW beam is less than 15°C, thus this material is potentially suitable for Gyrotron tubes of powers well in excess of 1MW. This places DIAFILM RF as the only material capable for running continuous wave, at powers in excess of 500 kW.
 

 



Click image for
larger view
 
 

Return to top >
 
DIAFILM PC
 
DIAFILM PC is specifically designed for precision mechanical cutting edge and wear component applications. Applications such as wear parts, microtomes and blades for medical applications, are where DIAFILM PC's high abrasion resistance combined with high fracture strength, stiffness and toughness are required.

 

Click image for larger view


 

Return to top >