JPH02121392A - Capacitor built-in composite circuit board and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a condenser which is not only excellent in mechanical strength but also possessed of a wide range of capacitance by a method wherein a protective layer is provided to the periphery of a dielectric layer, an electrode is provided onto the upside and the underside of the dielectric layer provided with the protective layer to form a capacitor section, and the condenser section is housed in an alumina insulation base composed of a specified composition. CONSTITUTION:An alumina insulating board 1 is formed as follows: raw material powder is mixed with a proper organic binder, a dispersing agent, a plasticizing agent, and a solvent and muddled so as to form liquid mud whose composition is 65wt.%<Al2O3<80wt.%/15wt.%<=SiO2<=25wt.%/0.5wt.%<=CaO<=5 wt.%/0.5wt.%<=MgO<=5wt.%: the liquid mud is molded into green sheets: and two or more green sheets are laminated. A capacitor section 2 is composed of a protective layer 4 and a dielectric layer 7 provided with an upper electrode 5 and a lower electrode 6 formed on its upside and underside respectively. The dielectric layer 7 is formed of barium titanate or lamthanum titanate ceramic and serves as a built-in capacitor by laminating an alumina insulating board provided with an electric wiring conductor pattern on it.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a capacitor-embedded composite circuit board having a capacitor, a resistor, and a conductor layer for electrical wiring, and particularly to a capacitor formed by simultaneously firing an insulating substrate and a dielectric material. The present invention relates to a built-in composite circuit board and a manufacturing method thereof.

[Conventional technology]

In recent years, various electronic devices have become smaller and more densely packaged through the use of semiconductor integrated circuit elements such as ICs and LSIs, and as a result, the insulating substrates on which the semiconductor integrated circuit elements are mounted are also smaller and more densely packed. ization has been required. Therefore, progress has been made in increasing the density of electrical wiring through miniaturization and multilayering, and in chipping passive components such as capacitors and resistors in electronic circuits. Double-sided mounting connected to a conductor layer for electrical wiring has been put into practical use.

However, with the remarkable development of semiconductor materials, there has been a demand for further miniaturization and high-density packaging of electronic devices, and it has become impossible to satisfy these demands by making the passive components smaller. was.

As a result, passive elements such as capacitors and resistors were thick-film printed by screen printing, etc., and the capacitor parts were formed at the same time as the insulating substrate was fired, along with the electrical wiring conductor layer formed by the same process, and then the resistors were printed. Composite ceramic substrates that are designed to be smaller and have higher densities by baking and hybridizing them have been proposed (Japanese Patent Application Laid-Open No. 103690/1982, Japanese Patent Application Laid-open No. 1986-1).
(See Publication No. 77696).

[Problem to be solved by the invention]

However, this conventional composite ceramic substrate incorporates a dielectric layer made of, for example, barium titanate-based ceramic into an alumina-based insulating base that has high mechanical strength, chemical stability, and excellent insulation properties. Therefore, it is difficult to increase the firing temperature of the alumina-based insulating base and the dielectric layer, and furthermore, the alumina-based ceramic of the insulating base and the barium titanate-based or lanthanum titanate-based ceramic of the dielectric layer are difficult to heat. If the ceramics are fired at the same time in contact with each other, there is a problem in that the ceramics react with each other, making it impossible to obtain a dielectric layer having the initial characteristics.

[Purpose of the invention]

The present invention was devised in view of the above-mentioned drawbacks, and its purpose is to simultaneously fire an alumina-based insulating substrate and a barium titanate-based and/or lanthanum titanate-based dielectric layer, thereby achieving the mechanical strength required for a capacitor. It is an object of the present invention to provide a composite circuit board with a built-in capacitor that can obtain electrical properties, particularly a wide range of capacitor capacities, and a method for manufacturing the same.

[Means to solve the problem]

The composite circuit board with a built-in capacitor according to the present invention has titania, calcium titanate, magnesium titanate, strontium titanate, or a partially stabilized material on the outer periphery of a dielectric layer made of barium titanate-based and/or lanthanum titanate-based ceramic. A protective layer made of at least one type of zirconia is provided, and electrodes are provided on the upper and lower surfaces of the dielectric layer having the protective layer to form a capacitor part, and the capacitor part has the following structure: 65 weight 11% < AIZO: l < 80
Weight i% 15% by weight ≦SiO□□≦25% by weight 0.5% by weight≦CaO≦5% by weight 0.5% by weight≦MgO≦5% by weight That is.

Further, in the method for manufacturing a composite circuit board with a built-in capacitor according to the present invention, the composition of the insulating substrate is 65% by weight.
ZO3<80 wt%15wt%≦SiO□≦2
5% by weight 0.5% by weight≦CaO≦5% by weight 0.5% by weight≦MgO≦5% by weight Ceramic raw materials are blended so that the mixture of the blend and the binder is molded by the doctor blade method. a step of printing a lower electrode in a predetermined pattern on a sheet by a screen printing method; a step of printing a dielectric pattern made of barium titanate-based and/or lanthanum titanate-based ceramic on the lower electrode; and the dielectric material. printing a protective layer pattern made of at least one of titania, calcium titanate, magnesium titanate, strontium titanate, or partially stabilized zirconia on the outer periphery of the pattern, overlapping a part of the protective layer and covering the dielectric material; a step of printing an upper electrode in a predetermined pattern on the upper surface of the pattern to form a capacitor section, and alternately laminating an insulating substrate on which the capacitor section is formed and another insulating substrate on which a conductor pattern for electrical wiring is formed,
A process of thermocompression bonding, debinding at a temperature of 200°C to 400°C in the air, and then firing at a temperature of 1280°C to 1350°C.
The method is characterized in that it consists of a step of stopping the body.

[For production]

The composition of the alumina-based insulating substrate is 65% by weight < Ah (h < ao 1% by weight
Barium titanate-based and/or titanic acid At the firing temperature of 1280° C. to 1350° C. at which the dielectric material made of lanthanum ceramic is sintered, the alumina insulating substrate can be fired and integrated with the dielectric material at the same time.

This is particularly effective when a barium titanate-based dielectric and a lanthanum titanate-based dielectric are simultaneously present on the insulating substrate.

In addition, in order to prevent the alumina-based insulating base from directly contacting the dielectric layer, a protective layer is formed on the outer periphery of the dielectric layer, so that even if another alumina-based insulating base is laminated, the alumina-based There is no direct reaction between the insulating substrate and the dielectric layer.

〔Example〕

Next, a composite circuit board with a built-in capacitor and a method for manufacturing the same according to the present invention will be explained in detail based on the embodiment shown in FIGS. 1 and 2.

FIG. 1 is a cross-sectional view showing an embodiment of a composite circuit board with a built-in capacitor according to the present invention, and FIG. 2 is a partially enlarged cross-sectional view for explaining the structure of the capacitor section of FIG.

In the figure, 1 is an alumina-based insulating substrate, 2 is a capacitor part, and 3 is a conductor for electrical wiring. Become.

The composition of the alumina-based insulating substrate 1 is 65% by weight.
＾12O3 < 80% by weight 15% by weight ≦SiO
Alumina (A1.03), silica (S
iO2), calcia (Cab), magnesia (MgO
), a suitable organic binder, dispersant, plasticizer, and solvent are added to and mixed with the ceramic raw material powder, and the slurry is formed into a sheet by, for example, the well-known doctor blade method. It is formed by laminating multiple green sheets.

In addition, a plurality of lower electrodes 6 are formed on the upper surface of the green sheet, and the lower electrodes 6 are made of a silver-palladium (Ag-Pd) alloy or the like, and are suitable for fully bending powder of the alloy. An alloy paste is prepared by adding and mixing a solvent and a solvent to form a paste, and the alloy paste is deposited on a green sheet in a predetermined pattern by a conventionally well-known screen printing method or the like.

This lower electrode 6 acts as one electrode of a capacitor section 2 built into an alumina-based insulating substrate 1, which will be described later.

In the green sheet having the lower electrode 6 on the upper surface, a dielectric layer 7 is formed on the upper surface of the lower electrode 6 with a thickness designed according to the desired capacitance of the capacitor, and the dielectric layer 7 is made of titanium. It is made of barium acid or lanthanum titanate ceramic, and the barium titanate or lanthanum titanate ceramic powder is mixed with an organic binder such as ethyl cellulose and a solvent to form a paste, which is then screen printed in the same manner as above. A dielectric M7 having dimensions slightly smaller than the dimensions of the lower electrode 6 is deposited on the upper surface of the lower electrode 6 by a method or the like. This dielectric layer 7 functions as a built-in capacitor by laminating an alumina-based insulating substrate 1b having a conductor pattern for electrical wiring, which will be described later.

Next, at least one type of titania, calcium titanate, magnesium titanate, strontium titanate, or partially stabilized zirconia is applied in a frame shape on the outer periphery of the dielectric layer 7 so as to partially overlap with the dielectric layer 7. The paste as a component is thick-film printed by the same screen printing method as described above to form the protection N4.

The thicker the protective layer 4 is, the greater the effect of preventing the reaction between the dielectric layer 4 and the alumina insulating base 1b.
In order to form the electric wiring conductor layer 3 and the resistor 8 on the surface of the protective layer 4 by screen printing, the thickness of the protective layer 4 is preferably about 10 μm to 50 μm because it is necessary to minimize surface irregularities.

The material of the protective layer 4 needs to be densified in the temperature range of 1280°C to 1350°C, which is fired at the same time as the alumina-based insulating base 1 and the dielectric layer 7, and adhere firmly to the alumina-based insulating base 1b. , titania, calcium titanate, magnesium titanate, strontium titanate, or partially stabilized zirconia.

Further, similar screen printing is performed using an alloy paste made of the same alloy as the lower electrode 6 on the upper surface of the dielectric layer 7 and overlapping a part of the protective layer 4 formed on the outer periphery of the dielectric layer 7. The upper electrode 5 is thick-film printed in a predetermined pattern using a method or the like. This upper electrode 5 acts as the other electrode of a capacitor section 2 built into an alumina-based insulating substrate 1, which will be described later.

It is preferable that the upper electrode 5 and the lower electrode 6 become dense without pinholes by firing.

Next, screen printing is performed using the alumina-based insulating base 1a on which the capacitor portion 2 is formed and the same electrode alloy paste as described above, and the alloy paste is applied to the through-hole portions 9 for establishing conduction between the upper and lower surfaces of the alumina-based insulating base 1b. and another alumina-based insulating substrate on which a conductor pattern for electrical wiring is formed are alternately laminated and bonded by thermocompression.

The obtained laminate was heated in the atmosphere from 200°C to 400”C.
Debinding at a temperature of 1280 to 1350
By integrally firing at a temperature of 0.degree. C., an alumina-based insulating substrate containing a built-in capacitor portion 2 having a dense electrode layer is obtained.

Thus, a conductor layer 3 for electrical wiring is formed on the surface of the alumina-based insulating substrate 1 after the integral firing using an Ag-Pb alloy paste by screen printing, and if desired, a paste containing ruthenium oxide (RuzQ3) as a main component. Each resistor 8 was printed using
A composite circuit board with a built-in capacitor can be obtained by firing at a temperature of °C.

In addition, if a paste containing copper (Cu) as the main component is used as the electrical wiring conductor layer 3, the resistor 8 may be coated with a paste containing lanthanum boride (LaB) or tin oxide (SnO2) as the main component. A composite circuit board with a built-in capacitor similar to that described above can be obtained by printing using the above-described method and baking it at a temperature of approximately 900° C. in a nitrogen atmosphere.

Next, the effects of the present invention will be explained based on experimental examples.

Alumina, silica, calcia, and magnesia are blended so that the composition of the alumina-based insulating substrate is shown in Table 1, and an appropriate organic binder and solvent are added and mixed to the blend to form a slurry. A green sheet with a thickness of about 200 μm was formed by a blade method, and then the green sheet was punched to obtain a 150 mm square sheet.

Next, A is sequentially printed using a thick film printing method such as screen printing.
A lower electrode pattern of about 2 to 10 mm square is formed using g-Pb alloy paste, and barium titanate or lanthanum titanate dielectric powder is mixed and kneaded with an organic binder such as ethyl cellulose and a solvent on the lower electrode pattern. The thickness is 20μm to 60μm by dielectric paste obtained by
A protective layer pattern is formed on the outer periphery of the dielectric pattern of 8 mm square using a paste mainly composed of the protective layer material shown in Table 1, so that it overlaps a part of the outer periphery of the dielectric pattern. overlapping a part of the protective layer and on the upper surface of the dielectric pattern is the same Ag-P as the lower electrode.
(b) Form upper electrodes using alloy paste. Thereafter, the binder is removed in the air at a temperature of 200°C to 400°C, and then fired in the air at the temperatures shown in Table 1.

Using the above evaluation sample, the presence or absence of a short circuit between the upper and lower electrode layers was measured using an LCR meter, and the presence or absence of a reaction between the dielectric layer and the alumina-based insulating substrate was confirmed.

The results are shown in Table 1.

The evaluation sample, in which it was confirmed that the reaction between the dielectric layer and the alumina-based insulating substrate was effectively prevented by the protective layer, was tested using the LCR meter at a frequency of I MHz and an input signal level of 1. Measure the capacitance and dielectric loss tangent as a capacitor under the measurement conditions of QVrns, calculate the relative dielectric constant from the capacitance, and calculate the dielectric constant from -25°C to 125°C.
The capacitance was measured, and the amount of change in the capacitance was calculated as the temperature characteristic (TCC).

As a result, the capacitor parts made of barium titanate all exhibited a relative permittivity (εr) of 1600 to 2O00 and a dielectric loss tangent (tanθ) of 0.8χ to 1.8χ, and the capacitor parts made of lanthanum titanate had a relative permittivity of 1600 to 2O00. (εr) is 52
〜56、Temperature characteristics: 155PPM/℃〜181PP
It was confirmed that the value was within the range of 100 yen/°C.

At the same time as the firing, a bending test piece having the same composition as the alumina-based insulating substrate was fired, and a three-point bending test was performed on the bending test piece in accordance with the JISR1601 standard, and the bending strength was 24 g/ It was confirmed that the value was within the range of 35Kg/mm2 to 35Kg/mm2.

[Margin below]

As is clear from Table 1, the content of Al2O2 in the composition of the alumina-based insulating substrate is 65% by weight or less (sample number 78
．． 79) or 5i02. If either the content of CaO or MgO exceeds the upper limit of the claimed range (sample numbers 25, 39.47, 48.49.54, 57.58
, 59, 60, 61.67.6872.73) or when the firing temperature exceeds 1350℃ (sample number L15
, 28, 42.62), the dielectric layer becomes oversintered or the protective layer cannot effectively prevent the reaction between the dielectric layer and the alumina-based insulating substrate, and as a result, the dielectric layer and A reaction occurs with the alumina-based insulating substrate.

Further, the content of AhOff is 80ffi1% or more (
sample number], 2) or “, 5iOz, CaO, MgO
If any of the contents does not reach the lower limit of the claimed range (sample numbers 3, 10.11, 12, 22.23,
24.37.38) or when the firing temperature is less than 1280°C (sample numbers 8.19, 31°46.66.76)
In this case, the alumina-based insulating substrate is insufficiently sintered, and the mechanical strength as an insulating substrate cannot be obtained, making it unusable.

In contrast, in all of the experimental examples related to the present invention, the reaction between the dielectric layer and the alumina-based insulating substrate was effectively prevented, and the mechanical strength as an insulating substrate was sufficiently high, and it was also It was confirmed that the electrical characteristics were fully satisfied.

Incidentally, on the alumina-based insulating substrate according to the present invention, Ag-Pd-based and Cu-based electrical wiring and Ru
It is possible to form resistors such as zOz-based, LaB-based, SnO□-based, etc. in the same manner as conventional alumina-based insulating substrates.

〔Effect of the invention〕

According to the capacitor-embedded composite circuit board and the manufacturing method thereof of the present invention, an alumina-based insulating substrate having a composition within the range of the present invention is heated at 1280°C to 1350°C at the same time as a barium titanate-based and/or lanthanum titanate-based dielectric material. It is possible to form an integral layer by firing at a firing temperature of °C, and at the same time prevent direct contact between the alumina-based insulating substrate and the dielectric material. Alternatively, by forming a protective layer made of one type of partially stabilized zirconia, it is possible to simultaneously sinter the alumina-based insulating substrate and the dielectric material and form them into an integral layer without any reaction. Composite with a built-in capacitor, which has a wide range of capacitor capacities, has an extremely excellent mechanical strength of the board, and can also form a conductor layer for electrical wiring and a resistor on the surface of the board. A circuit board can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of a composite circuit board with a built-in capacitor according to the present invention, and FIG. 2 is a partially enlarged cross-sectional view for explaining the configuration of the capacitor portion of FIG. 1. 6... Lower electrode 7... Dielectric layer Patent applicant (663) Kyocera Corporation 1, LA, LB 2 ・ ・ 3 ・ ・ 4 ・ ・ 5 ・ Alumina-based insulating base capacitor section Conductor layer protective layer upper electrode for electrical wiring

Claims (1)

[Claims] (1) Barium titanate (BaTiO_3)-based and/or lanthanum titanate (LaTi_2O_3)-based ceramics is used as a dielectric layer, a protective layer is provided on the outer periphery of the dielectric layer, and the protective layer is A capacitor portion is formed by providing electrodes on the upper and lower surfaces of the dielectric layer having the following properties: 65 wt%<Al_2O_3<80 wt% 15 wt%≦SiO_2≦25 wt% 0.5 wt%≦CaO≦5 A composite circuit board with a built-in capacitor, characterized in that it is built in an alumina (Al_2O_3)-based insulating substrate having a composition of 0.5% by weight≦MgO≦5% by weight. (2) The protective layer is titania (TiO_2), calcium titanate (CaTiO_3), magnesium titanate (MgTiO_3), strontium titanate (SrT
iO_3) or partially stabilized zirconia (ZrO_2)
A composite circuit board with a built-in capacitor according to claim 1, comprising at least one of the following. (3) The composition of the insulating substrate is as follows: 65% by weight<Al_2O_3<80% by weight, 15% by weight≦SiO_2≦25% by weight, 0.5% by weight≦CaO≦5% by weight, 0.5% by weight≦MgO≦5% by weight. A step of printing a lower electrode in a predetermined pattern on a green sheet formed by blending ceramic raw materials and molding a mixture of the blend and a binder, and printing barium titanate (BaTiO_3) on the lower electrode.
system and/or lanthanum titanate (LaTi_2O_5
) printing a dielectric pattern made of ceramic, printing a protective pattern on the outer periphery of the dielectric pattern, and placing an upper electrode in a predetermined manner on the top surface of the dielectric pattern, overlapping a part of the protective layer. a step of printing a pattern to form a capacitor portion, and alternately laminating an insulating substrate on which the capacitor portion is formed and another insulating substrate on which a conductive pattern for electrical wiring is formed,
The process of heat-compression bonding, debinding in the atmosphere, and then 1
A method for producing a composite circuit board with a built-in capacitor, comprising the step of baking and integrating at a temperature of 280°C to 1350°C. (4) The protective layer is composed of titania (TiO_2), calcium titanate (CaTiO_3), magnesium titanate (MgTiO_3), strontium titanate (SrTi
4. The method for manufacturing a capacitor-embedded composite circuit board according to claim 3, which comprises at least one of O_3) and partially stabilized zirconia (ZrO_2).