JPS59134812A - Ceramic circuit board containing condenser - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to electrical circuits requiring high-density packaging.The remarkable development of semiconductor materials in recent years has had a great impact on the miniaturization of equipment. Along with this, major changes were required, especially in terms of miniaturization of the circuit components and circuit boards that constitute the components of devices. As a result, passive elements such as resistors and capacitors have changed to high-density, low-cost mounting formats, such as chips and hybridization by thick-film printing on substrates. However, wiring boards, which are used for interconnecting electrical circuits, have been miniaturized through fine-line wiring and high-density wiring through multilayer wiring. However, when trying to further miniaturize devices, there are limits to simply miniaturizing individual circuit components and circuit boards as has been done in the past. We must aim for this.

A typical high-density wiring board is an alumina wiring board. This wiring board uses high-melting point metals such as tungsten (W) and molybdenum (MO) as the wiring conductor material, but the board material is alumina (A1).
2o, +) can be simultaneously sintered in a reducing atmosphere. Instead, a multilayer wiring board can be easily obtained by simply providing an alumina insulating layer and a wiring conductor layer on a raw alumina sheet and firing them simultaneously. In addition, the thermal, mechanical, and electrical properties of the alumina sintered body are the best for use as a circuit board. Taking advantage of these characteristics, alumina wiring boards are widely used as high-density wiring boards for ICs, LSIs, etc., and are especially effective as wiring boards for digital ICs that handle high-speed signals and have a large number of wires. .

However, although the alumina wiring board has such great features, there is one drawback that cannot be overcome. The above-mentioned wiring board is characterized only by the high density of the wiring, and in circuits such as analog circuits that require a large number of resistors and capacitors, a large effect cannot be obtained in terms of high density of the entire board. In other words, unlike digital circuits, in analog circuits it is not sufficient to simply have high wiring density, and it is important to increase the density of the entire circuit board, including many resistors and capacitors. However, the conductive material used in alumina wiring boards is a base metal that is easily oxidized, so when, for example, a resistor or capacitor is baked into a thick film after sintering the board, the atmosphere must be reducing and conductive. . Recently, silicide-glass based glazed resistors that can be baked in a reducing atmosphere have been put into practical use as resistance materials, but none have been used as capacitor materials. For this reason, we had to use a very complicated method that could not be called high-density mounting, such as mounting a chip-shaped capacitor part & that was sintered in the air on a sintered wiring board later. . Still, another method is to use an alumina insulating layer between conductor layers as a capacitor. However, the dielectric constant of the alumina sintered body is at most about 8 to 1o, so if the thickness of the insulating layer is 30 μm, the capacitance per 1 obtained between the opposing electrodes is only about 3 pF. Therefore, in order to obtain a large capacity capacitor, the electrode area must be increased,
It is necessary to further reduce the thickness of the insulating layer or increase the number of laminated layers.

Such a method cannot be said to be a good idea in terms of cost and process.

As explained above, in conventional alumina wiring boards with tungsten or molybdenum conductor wiring, the wiring density can be increased, but large capacitance capacitors cannot be formed, making it difficult to implement high-density packaging as a whole board.
Unfortunately, the reality is that its scope of use is extremely limited.

OBJECTS OF THE INVENTION An object of the present invention is to provide a ceramic circuit board that enables high-density packaging in which a large capacitor is formed simultaneously with sintering.

Structure of the Invention The ceramic circuit board of the present invention comprises a ceramic insulating substrate, a conductor layer made of tungsten or molybdenum as a wiring material, and cerium aluminate (CeA103).
) and a capacitor layer.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings.

The drawing shows a cross-sectional view of a ceramic circuit board including a capacitor in one embodiment of the present invention. In the figure, 1 is a ceramic substrate, 2 and 4 are conductor layers made of tungsten or molybdenum, and 3 is a capacitor layer made of CeAlO3.

Turpentine oil containing 10 wt% ethyl-4/reulose dissolved in CeA103 powder was added and kneaded well to form a capacitor paste. As a ceramic insulating substrate, a small piece 1 of raw alumina with a thickness of 1 mm was prepared by adding poly vinyl no final resin as a binder to an inorganic composition containing atubenium oxide (Aβ203) as a main component. A small piece of this raw sheet has a grain size of 1μ on one side of the piece.
A conductive layer 2 was formed by printing a conductive paste made of tungsten or molybdenum of approximately m thickness. The capacitor paste was printed on the conductor layer 2 to form a capacitor layer 3, and the conductor paste was further printed to form a conductor layer 4. The printed raw sheet pieces were fired at a high temperature of 1400 to 1600° C. in a reducing atmosphere containing a mixed gas of hydrogen and nitrogen and a small amount of water vapor. The thickness of one indenser layer after sintering was 30 μm, and the opposing area between conductor layers 2 and 4 was 2s7.

The table below shows typical characteristics of the circuit board capacitor obtained in this example. From the table, it can be seen that the circuit board of this example is a circuit board equipped with a large capacitor having excellent capacitor characteristics.

Furthermore, no differences in capacitor characteristics due to differences in conductor layer materials were observed.

This is considered to be because the capacitor portion 0ceAlo3 itself in this actual case has a high dielectric constant and is a compound with a perovskite structure that is stable even at high temperatures in a reducing atmosphere.

In the embodiment, a so-called alumina substrate containing aluminum oxide as a main component is used as the ceramic substrate, but the present invention is not limited to this, and any material that can be used satisfactorily as an insulating substrate after sintering may be used. In addition, in the example, only one capacitor layer is provided on one side of the substrate, but the capacitance value of the capacitor can be increased by alternately and repeatedly laminating the capacitor layer and the conductor layer during printing.

Furthermore, although the capacitor layer is composed of a Cehlos tailored layer, a loosening additive may be added to improve capacitor properties.

Effects of the Invention As is clear from the above explanation, the present invention enables the fabrication of a circuit board containing a large capacity capacitor at the same time as the sintering of the substrate by forming a capacitor layer made of cerium aluminate (CeAlO3) on a ceramic substrate. This has the advantage of providing a circuit board with extremely advantageous circuit configurations, including capacitor layer function, compared to wiring boards where only the wiring function has been emphasized in the past, and has practical value. is extremely high.

[Brief explanation of the drawing]

The drawing is a sectional view showing one embodiment of the alumina circuit board of the present invention. 1... Alumina substrate, 2... Electrode, 3
...Capacitor layer, 4... Electrode.

Claims (1)

[Claims] -f=7 A ceramic circuit board including a capacitor comprising a Minoku insulating substrate, a conductor wiring layer made of tungsten or molybdenum, and a capacitor layer made of cerium chlorate (ceh, eo3).