Diamond body

Details Diamond body Diamond body

1999-07-12

2003-03-25

Flanigan, Allen (Department: 3743)

Heat exchange

Expansion and contraction relieving or absorbing means

C165S185000, C361S704000

Reexamination Certificate

active

06536509

ABSTRACT:

TECHNICAL FIELD
The invention concerns a diamond body for connection to at least one component.
BACKGROUND ART
It is known from the article “Diamond Films as Thermal Conductors and Electrical Insulators Applied to Semiconductor Power Modules” by B. Fiegl, R. Kuhnert, H. Schwarzbauer and F. Koch in Diamond and Related Materials, 3 (1994, pages 658 to 662 that diamond bodies can be used to remove large amounts of heat, for example, from semiconductor components as heat sources, because of the very high thermal conductivity of diamond.
As known from the article “Applications of CVD Diamond in the Thermal Management” by G. Lu in 2
nd
International Conference on the Applications of Diamond Films and Related Materials, Editors M. Yoskikawa, M. Murakawa, Y. Tzeng and W. A. Yarbrough, MY, Tokyo, 1993, large amounts of heat can also be quickly taken off with so-called heat spreading, i.e., effective spatial distribution of the heat, with diamond plates deposited from the gas phase as diamond bodies based on the high thermal conductivity, especially from point heat sources.
However, as is known from the article “Thermal Stress in Diamond Films” by V. G. Ralchenko, E. D. Obraztova, K. G. Korotoushenko et al. in Applications of Diamond Films and Related Materials: Third International Conference, 1995, Editors A. Feldman, Y. Tzeng, W. A. Yarbrough et al., the problem then occurs that because of the very low heat expansion coefficient of diamond, significant thermally induced mechanical stresses sometimes occur during connection to other materials, like semiconductors or metals by soldering and during operation, generally at room temperature, which, under some circumstances, can disadvantageously lead to destruction of the connection or the diamond body.
It was previously proposed, to reduce such thermally induced mechanical stresses in conjunction with applied components, to provide a thick, soft solder layer during connection of a diamond body to components, in order to compensate for the thermally induced mechanical stresses via their elasticity in the soldered joint. However, a shortcoming of this procedure is that the heat resistance is substantially increased on this account, so that heat removal is reduced, especially during heat spreading.
DISCLOSURE OF INVENTION
The underlying task of the invention is to devise a diamond body of the type mentioned at the outset, in which the hazard of loosening of a connection to other, especially relatively inelastic materials, or destruction of the diamond body because of thermally induced mechanical stresses, especially during joining with exposure to heat, is reduced.
This task is solved in a diamond body of the type mentioned at the outset in that at least one elongated recess is made, which extends at an angle to thermally induced mechanical stresses from the connection with the component or each component.
By provision of at least one elongated recess in the diamond body, which extends at an angle to thermally induced mechanical stresses during temperature differences, for example, during connection of the diamond body to the component with exposure to heat and room temperature or, under some circumstances, also between an operating state with very high temperature and a rest state, these stresses are at least partially compensated by the obliquely aligned recess or each obliquely aligned recess, because of the increase in mobility of the diamond body achieved by this, so that the hazard of, say, flaking off of the diamond body is substantially reduced, but the utilized properties of diamond, like very good electrical insulation behavior or excellent thermal conductivity, are essentially retained.
Preferably, a number of resources are provided, which are preferably aligned at right angles to the mechanical stresses. It is then expedient that the recesses be aligned under a small angle to the heat flow directions established by the geometry of the diamond body, as well as the arrangement of heat sources and heat sinks formed by the component or each component. It is particularly advantageous if a number of recesses run essentially at right angles to mechanical stresses and essentially parallel to the heat flow directions.
In one embodiment a number of recesses are designed as inner slits that are open to the two surfaces of the diamond body. In other embodiments the recesses are designed as slits open to three surfaces, in which the corresponding residual material thickness to an edge side adjacent to the end of the slit is smaller than the depth of each slit. Particularly high equalization of thermally induced mechanical stresses in conjunction with narrow elongated components is achieved because of this, in which it is expedient for this case for good heat spreading that parallel slits be provided aligned transversely to an elongated heat source or heat sink.
With a grid-like arrangement of several point-like heat sources or heat sinks as components, it is advantageous to arrange the recesses to extend between adjacent heat sources and to enclose each heat source, in order to spread the generated heat over a larger surface area, on the one hand, and to locally compensate for mechanical stresses generated in the region of each heat source, on the other hand.
Components, like semiconductor lasers or computer components, to be joined with solder, especially even at relatively high temperatures, can be applied with diamond bodies so configured without the hazard of separations, breaks, and/or deformations of the applied components or diamond bodies, in which a very thin solder layer with a corresponding limited heat resistance can be used advantageously, owing to compensation of the mechanical stresses by the recesses.
These and other objects and advantages of the present invention will become clear to those skilled in the art in view of the description of the best presently known mode of carrying out the invention and the industrial applicability of the preferred embodiment as described herein and as illustrated in the several figures of the drawings.


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