JP4422067B2 - Manufacturing method of ceramic substrate - Google Patents

Description

The present invention relates to a method for manufacturing a ceramic substrate in which a ceramic substrate and a graphite sheet are integrated.

  In recent years, as seen in mobile phone electronic devices, miniaturization and higher functionality have been promoted, and in various electronic components constituting such electronic devices, related electronic components have been combined.

  And in the compounding of such electronic parts, heat generating parts such as high-frequency amplifiers are compounded with functional ceramic parts in which electronic circuits such as high-frequency switches are formed by providing appropriate internal electrodes on the inner layer of the ceramic substrate. The form to do is increasing.

  When mounting a heat-generating component on a ceramic substrate that forms a functional ceramic component, the ceramic substrate serves as a heat sink for the heat-generating component, so it is necessary to efficiently dissipate the heat generated in the heat-generating component within the ceramic substrate. Therefore, conventionally, a ceramic substrate has a graphite sheet attached to the upper surface on which a heat generating component is mounted.

For example, Patent Document 1 is known as prior art document information related to the invention of this application.
JP 2003-174204 A

  However, in a composite part in which a graphite sheet is attached to a ceramic substrate, an adhesive is used when the graphite sheet is attached to the ceramic substrate. Therefore, it has been difficult to obtain a sufficient heat transfer effect.

  Accordingly, the present invention aims to solve such problems and improve the thermal conductivity in a composite part composed of a ceramic substrate and a graphite sheet.

In order to achieve this object, the present invention particularly forms a metal oxide layer in advance on the joint surface of the graphite sheet, contacts the metal oxide layer with an unsintered ceramic substrate, and fires in this state. In other words, the ceramic oxide substrate and the graphite sheet are integrated by bringing the metal oxide layer into contact with the ceramic substrate in a sintered state and heating in this state .

According to this method, since the metal oxide formed on the graphite sheet is combined with the ceramic substrate in the firing stage and integrated with each other, it is possible to eliminate the adhesive layer that has heretofore hindered heat conduction. The thermal conductivity of the ceramic substrate integrated with the graphite sheet can be increased.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  In FIG. 1, a high-frequency amplifier 5, which is an example of a heat-generating component, is mounted on a composite component 4 in which a graphite sheet 3 is provided on the upper surface of a multilayer high-frequency switch 2 which is an example of a functional ceramic component using a ceramic substrate 1. It is the schematic diagram which showed the high frequency module.

  The multilayer high-frequency switch 2 is a diode that is difficult to form in the substrate in addition to the ceramic substrate 1 in which the inductor, capacitor, and strip line are formed by the electrode pattern 6 in the inner layer portion of the ceramic substrate 1 composed of a plurality of dielectric layers. A high frequency switch circuit is formed by mounting circuit elements 7 such as the above on the upper surface of the ceramic substrate 1, and heat generated from the high frequency amplifier 5 is formed on the upper surface of the laminated high frequency switch 2 on the surface of the mounting surface of the high frequency amplifier 5. The graphite sheet 3 for dispersing inward is provided.

  That is, the high-frequency module has a configuration in which the high-frequency amplifier 5 is mounted on the composite component 4 in which the graphite sheet 3 is provided on the upper surface of the ceramic substrate 1 on which the multilayer high-frequency switch 2 is formed.

  As the graphite sheet 3, a polymer resin sheet such as polyimide is carbonized at a temperature of 1200 ° C. or higher, and then graphitized at a temperature of 2600 ° C. or higher, so that the carbon is two-dimensionally dense as shown in FIG. Examples include a multi-layer structure of bonded carbon layers, which exhibits high heat conduction characteristics in the bonding surface of carbon, one in which expanded graphite is formed into a layer, and one in which graphite fiber is formed into a layer.

  The composite component 4 including the multilayer high-frequency switch 2 and the graphite sheet 3 has a structure in which a metal oxide layer 8 is provided between the graphite sheet 3 and the multilayer high-frequency switch 2 as shown in FIG. With this structure, the heat generated from the high-frequency amplifier 5 mounted on the composite component 4 can be efficiently distributed to the multilayer high-frequency switch 2.

  In this regard, as shown in FIG. 3, after the metal oxide layer 8 is formed on the graphite sheet 3 by a plating method or a sputtering method, the metal layer is subjected to a chemical treatment or a heat treatment in an oxidizing atmosphere. The graphite sheet 3 provided with the metal oxide layer 8 is stacked on the upper surface of the green body of the ceramic substrate 1 forming the multilayer high-frequency switch 2, and these are integrally fired to oxidize at the firing stage. When the oxygen contained in the metal layer 8 or the metal oxide layer 8 is combined with an oxidizing substance such as alumina or silica that forms the ceramic substrate 1, and after firing, the ceramic substrate 1 and the graphite sheet 3 are integrated. A conventional resin bonding layer for bonding the ceramic substrate 1 and the graphite sheet 3 is provided. Eliminates the necessity of, at the heat conduction efficiency from the graphite sheet 3 to ceramic substrate 1 is enhanced.

  When the ceramic substrate 1 in the sintered state and the graphite sheet 3 are integrated, the graphite sheet 3 is placed on the ceramic substrate 1 in the sintered state and heat-treated again, so that Similarly, since the metal oxide layer 8 is bonded to the ceramic substrate 1, they can be integrated, and the heat conduction efficiency from the graphite sheet 3 to the ceramic substrate 1 is increased.

  That is, the local heat generated in the high frequency amplifier 5 is quickly dispersed in the sheet surface direction by the graphite sheet 3 and this dispersed heat is transmitted to the laminated high frequency switch 2 serving as a heat sink. The thermal conductivity can be made higher.

  Since the graphite sheet 3 has a layered microstructure and is softer than the ceramic substrate 1, even when the high frequency amplifier 5 is mounted on the laminated high frequency switch 2 made of the hard ceramic substrate 1, The graphite sheet 3 also functions as a buffer material against external stresses such as a drop impact on the high frequency amplifier 5, and the reliability of the high frequency switch module in which these are integrated can be improved.

  In the above-described embodiment, the multilayer high-frequency switch 2 using the ceramic substrate 1 has been described with the high-frequency amplifier 5 as a heat-generating component. However, the present invention is not limited to such a limitation. In the composite component 4 in which the graphite sheet 3 is integrated with the ceramic substrate 1 on which is mounted, the same operations and effects are exhibited.

  In this embodiment, the structure in which the graphite sheet 3 is disposed on the upper surface of the ceramic substrate 1 has been described. However, although not particularly illustrated, the graphite sheet 3 is used as an inner layer portion of the ceramic substrate 1. Even in the case of an embedded structure, the same effect can be obtained. However, in this case, the buffer function against the external stress described above does not work.

The present invention relates to a ceramic substrate made of a ceramic substrate and the graphite sheet has the effect of increased thermal conductivity in the composite component, useful for ceramic substrate used for electronic devices, particularly travel of small high functionality.

Sectional drawing which represented typically the high frequency switch module using the composite component in one Embodiment of this invention Schematic diagram showing the structure of the graphite sheet forming the composite part Schematic diagram showing the manufacturing method of the composite part

Explanation of symbols

1 Ceramic substrate 3 Graphite sheet 4 Composite part 8 Metal oxide layer

Claims (2)

A method of manufacturing a ceramic substrate on which a heat generating component is mounted , wherein a metal oxide layer formed on a graphite sheet is brought into contact with a ceramic substrate in an unsintered state, and the ceramic substrate is baked in the contacted state. A method for producing a ceramic substrate, wherein the ceramic substrate and the graphite sheet are integrated. A method of manufacturing a ceramic substrate on which a heat-generating component is mounted , wherein a metal oxide layer formed on a graphite sheet is brought into contact with a ceramic substrate in a sintered state, heated in the contact state, and the ceramic substrate and A method for producing a ceramic substrate, wherein the graphite sheet is integrated.

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