Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Composite having voids in a component
Reexamination Certificate
2000-06-21
2002-06-04
Copenheaver, Blaine (Department: 1771)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Composite having voids in a component
C428S131000, C428S137000, C428S138000, C428S901000, C428S317900, C428S319100
Reexamination Certificate
active
06399187
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a metal-ceramics composite having a reinforcing material combined with a metal containing aluminum as the main component, particularly a metal-ceramics composite excellent in processability. Further, the present invention relates to a heat dissipation device made of a highly thermal-conductive composite which is excellent in thermal conductive characteristics and light in weight and which is useful for a heat sink for semiconductor parts such as ceramic substrates or IC packages.
2. Discussion of Background
Circuit boards for mounting semiconductor elements are known which employ various substrates such as ceramic substrates or resin substrates. In recent years, along with the progress in miniaturization of the circuit boards and in high densification of semiconductor elements, a further improvement is desired in the heat dissipation characteristics of the circuit boards. For a ceramic substrate, an attention has been drawn to e.g. silicon carbide (SiC), aluminum nitride (AlN) or silicon nitride (Si
3
N
4
)
When a ceramic substrate is to be employed as a circuit board or a substrate for a package, it is necessary to dissipate a heat generated from a semiconductor element to the exterior by means of a heat sink provided in contact with the rear side of the substrate and further by means of heat dissipation parts such as heat dissipation fins, to secure performance characteristics of the semiconductor element.
When a commonly employed metal material such as copper (Cu) is used for such a heat sink, cracks, etc. may form on the ceramic substrate under heat cycles during heat bonding or production or during the actual use, due to a difference in thermal expansion between the ceramic substrate and the heat sink. Accordingly, when a ceramic substrate is used in the field where high reliability is required, it has been common to employ e.g. Mo or W having a high melting point and having a small difference in the thermal expansion from the ceramic substrate, as the heat sink.
However, a heat dissipation device employing a high melting point metal such as Mo or W, is heavy as Mo or W is a heavy metal, such being undesirable for applications where light in weight of the heat dissipation device is desired. Further, the above-mentioned heat dissipation device is expensive. Accordingly, in recent years, an attention has been drawn to a metal-ceramics composite (hereinafter referred to simply as a composite) so-called MMC (metal matrix composite) having copper, aluminum or an alloy thereof reinforced with inorganic fibers or particles.
A metal-ceramics composite is a composite which is prepared usually by preliminarily molding inorganic fibers or particles as a reinforcing material, to form a preform and infiltrating a metal or alloy as a base material (matrix) into the fibers or particles of the preform. As the reinforcing material, ceramics of e.g. alumina, silicon carbide, aluminum nitride, silicon nitride, silica or carbon, is employed.
When a metal-ceramics composite is used for the preparation of the above-mentioned heat dissipation device, highly precise plane processing or hole processing is, for example, required, but the composite has had a problem that it is poor in the processability as a ceramics is combined, and the cost for processing tends to be high.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above problem of the metal-ceramics composite, and it is an object of the present invention to provide a metal-ceramics composite to which a usual metal processing method can easily be applied, so that it can be processed inexpensively.
When a metal-ceramics composite is to be practically employed, it may sometimes be fastened to e.g. a heat dissipation fins by means of processed holes, and in such a case, it may happen that the strength of the composite is inadequate in the vicinity of the holes and no adequate fixing or close contact can be accomplished. Accordingly, it is another object of the present invention to provide a metal-ceramics composite having the mechanical properties improved in the vicinity of the holes.
A further object of the present invention is to provide a metal-ceramics composite, whereby cavities can be prevented which are likely to form during the infiltration operation, and formation of recesses on the surface of the hole portions can be prevented thereby to prevent shaping failure such that openings of the holes will not be flat at the time of hole processing.
A still further object of the present invention is to provide a heat dissipation device which is light in weight and excellent in the heat dissipation property and which is suitable for electric parts including ceramic substrates and IC packages, particularly electric parts for mobile instruments such as automobiles and electric railways.
The present inventors have conducted extensive studies to accomplish the above objects and as a result, have found that when a specific material is applied to portions of a composite where processing is required, it is possible to obtain holes which are excellent in processability and which have shaping accuracy improved simply by applying a conventional metal processing method without formation of cavities or recesses therearound, and to obtain a metal-ceramics composite whereby such holes may be employed for bolts without deteriorating mechanical properties. The present invention has been accomplished on the basis of this discovery.
That is, the present invention provides a metal-ceramics composite comprising a porous inorganic structure and a metal containing aluminum as the main component, infiltrated into the porous inorganic structure, wherein a part of the porous inorganic structure is made of an inorganic fiber and a hardened product of a hydraulic inorganic substance.
The present invention provides the above metal-ceramics composite wherein the porous inorganic structure contains silicon carbide as the main component, the above metal-ceramics composite wherein the inorganic fiber is at least one member selected from the group consisting of boron nitride, silicon carbide, alumina, silica, silicon nitride and carbon, and the above metal-ceramics composite wherein the hydraulic inorganic substance is at least one member selected from the group consisting of calcia, alumina, magnesia, alumina cement and Portland cement.
The present invention provides the above metal-ceramics composite wherein the inorganic fiber is alumina, and the hydraulic inorganic substance is alumina, and preferably, the above metal-ceramics composite wherein the porous inorganic structure contains silicon carbide as the main component.
Further, the present invention provides the above metal-ceramics composite wherein the porous inorganic structure is a plate and has holes (through-holes) communicating to both sides of the plate, preferably, the above metal-ceramics composite wherein an inorganic fiber and a hardened product of a hydraulic inorganic substance, is filled in the through-holes of the porous inorganic structure, more preferably, the above metal-ceramics composite wherein the-porous inorganic structure contains silicon carbide as the main component, the inorganic fiber is alumina, and the hydraulic inorganic substance is alumina.
Further, the present invention provides the above metal-ceramics composite wherein a portion of the metal-ceramics composite comprising the inorganic fiber, the hardened product of a-hydraulic inorganic substance and the metal containing aluminum as the main component, is processed to form the through-holes.
Further, the present invention provides a heat dissipation device comprising the above metal-ceramics composite and a nickel layer formed on at least one main surface of the composite.
Still further, the present invention provides a process for producing a metal-ceramics composite, which comprises a step of molding a silicon carbide powder, followed by firing, to obtain a preform, a step of forming through-holes in the preform, fil
Hirotsuru Hideki
Miyai Akira
Terasaki Ryuichi
Copenheaver Blaine
Denki Kagaku Kogyo Kabushiki Kaisha
Vo Hai
LandOfFree
Metal-ceramics composite, heat dissipation device employing... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Metal-ceramics composite, heat dissipation device employing..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Metal-ceramics composite, heat dissipation device employing... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2973164