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Laser cutting
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Due to the extreme hardness of diamond a
mechanical cutting or sawing of the diamond wafers is not
possible.
For that reason a Q-switched Nd:YAG laser is applied for cutting
them into desired shapes. |
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Watch escape wheel prepared by high-precision
laser cutting |
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Grinding and Polishing
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After
deposition, the coarse grained films are ground and polished to
the desired thickness. For this purpose a high speed lapping
machine capable of treating three samples simultaneously has
been developed at Fraunhofer IAF. Diamond wafers with up to 5"
in diameter can be polished.
Rms roughness values in the sub-nanometer range (superpolishing)
can be achieved under optimized conditions
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Surface profile of a polished CVD diamond wafer
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Metallization
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For the preparation of diamond
heat-spreaders the metallization is of central importance.
Various metallization schemes consisting of several metal layers
have been developed. Each layer acts either as adhesion layer,
diffusion barrier, or as surface layer improving the wetting
behaviour of the solder. Thick gold layers are used as
electrical conductors for high current densities.
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Metallization patterns prepared by optical
lithography
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Soldering / Brazing
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Soldering and brazing techniques are used e.g. to mount
electronic devices on diamond heatspreaders or to prepare
diamond-metal joints e.g. for the realization of UHV vacuum
windows. |
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UHV diamond window used as optical port
in synchrotron beam lines. |
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