JP2700920B2 - Composite circuit board with built-in capacitor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite circuit board with a built-in capacitor having a capacitor, a resistor and a conductor layer for electric wiring, and more particularly to a capacitor formed by simultaneously firing an insulating base and a dielectric. The present invention relates to a built-in composite circuit board.

[Conventional technology]

In recent years, the use of semiconductor integrated circuit devices such as ICs and LSIs for various electronic components has rapidly progressed in miniaturization and high-density mounting, and accordingly, the insulating substrate on which the semiconductor integrated circuit devices and the like are mounted has become smaller and smaller. Higher densities have been required. Therefore, the miniaturization and multi-layering of the wiring and the increase in the density of passive components such as capacitors and resistors in electronic circuits have been promoted, and the miniaturized passive components have been provided on both sides of an insulating substrate. The double-sided mounting connected to the wiring conductor layer has been put to practical use.

However, with the remarkable development of semiconductor materials, further miniaturization and high-density mounting of electronic components are required, and the miniaturization of the passive components can satisfy the demand. Was gone.

Therefore, in order to respond to such a demand, a capacitor part, which is a passive element, is printed on the insulating substrate by a thick film printing method or the like, and simultaneously with firing of the insulating substrate together with the electrode layer and the internal wiring conductor layer formed in the same manner. After that, a conductor layer and a resistor layer for electric wiring are formed on the surface of the insulating substrate by the same screen printing method, and the conductor layer and the resistor layer are baked to be hybridized, thereby reducing the size and the density. There has been proposed a composite ceramic substrate to be formed into a plastic (see Japanese Patent Publication No. 63-55795).

[Problems to be solved by the invention]

However, in this conventional composite ceramic substrate, for example, a ceramic mainly composed of barium titanate (BaTiO ₃ ) is used as a dielectric layer, and the dielectric layer has high mechanical strength, is chemically stable, and has an insulating property. When embedded in an insulating base mainly composed of alumina excellent in alumina, when the alumina base ceramic of the insulating base and the ceramics of the dielectric layer made of barium titanate are simultaneously fired in a contact state, the ceramics react with each other. Therefore, it is difficult to match the problem that a dielectric layer having desired characteristics cannot be obtained and the firing temperature of the ceramics made of alumina for the insulating base and the ceramics made of barium titanate for the dielectric layer, In addition, cracks occur in the dielectric layer due to the difference in thermal expansion between the insulating base and the dielectric layer. Corrupted voltage is lowered.

[Object of the invention]

The present invention has been devised in view of the above-mentioned drawbacks, and its object is to provide an insulating layer having MgO, SiO ₂ , and CaO as main components and having excellent high-frequency insulating properties, and a barium titanate (BaTi) having a high dielectric constant.
It is an object of the present invention to provide a composite circuit board including a capacitor having a high capacitance by simultaneously firing a dielectric layer containing O ₃ ) as a main component.

[Means for solving the problem]

The composite circuit board with a built-in capacitor according to the present invention is characterized in that a ceramic mainly composed of barium titanate (BaTiO ₃ ) is used as a dielectric layer, and an electrode layer is provided on upper and lower surfaces of the dielectric layer to form a capacitor part. In a composite circuit board with a built-in capacitor in which a capacitor portion is sandwiched between insulator layers, magnesia (MgO) in a range surrounded by the following points A, B, C, D, and E shown in FIG. , Silica (Si
It is characterized by being composed of ceramics containing O ₂ ) and calcia (CaO) as main components and containing at least forsterite (Mg ₂ SiO ₄ ) as a crystal phase. However,
X, Y and Z are magnesia (MaO) and silica (SiO
₂ ) and weight% of calcia (CaO).

XYZ A 60 36 4 B 46 50 4 C 20 50 30 D 40 30 30 E 60 30 10 Further, the insulator phase is forsterite (Mg ₂ SiO ₄ ),
Monticerite (CaMgCiO ₄ ) or akermanite (Ca
₂ MgSi ₂ O ₇ ).

Furthermore, the composite circuit board with a built-in capacitor of the present application is obtained by simultaneously firing a dielectric layer and an insulating layer sandwiching a capacitor portion formed of the dielectric layer and the electrode layer.

That is, the composition of the insulator layer was such that MgO was 6 in FIG.
If it exceeds 0% by weight, the sintering temperature becomes 1360 ° C. or higher, and the sintering cannot be performed simultaneously with the above-mentioned dielectric material. On the other hand, if it is less than 20% by weight, the sintering temperature becomes 1220 ° C. or less, and the sintering cannot be performed simultaneously with the dielectric material.

If the content of SiO ₂ exceeds 50% by weight, the coefficient of thermal expansion of the insulator layer decreases, and cracks occur in the dielectric layer due to the difference in thermal expansion between the insulator layer and the dielectric layer. Cannot be obtained. On the other hand, if it is less than 30% by weight, the firing temperature is 1360.
° C or more, and cannot be co-fired with the dielectric material.

On the other hand, if CaO exceeds 30% by weight or less than 4% by weight, the reactivity with ceramics composed of barium titanate becomes extremely large, and a dielectric layer having desired characteristics cannot be obtained. Beyond, CaSiO ₃ or Ca ₂ S
Calcium silicate such as iO ₄ precipitates and has poor moisture resistance.

Therefore, the composition of the insulator layer is A, B, C,
It is specified within the range surrounded by the points D and E.

[Action]

The composition of the insulator layer sandwiching the capacitor portion is such that magnesia (MgO), silica (SiO ₂ ) and calcia (CaO), which are the main components, are added to the points A, B, C, D and E shown in FIG. By adjusting so as to fall within the enclosed range, the insulator material is simultaneously fired and integrated at a firing temperature of 1240 ° C. to 1340 ° C. at which a dielectric material made of barium titanate (BaTiO ₂ ) is sintered. In addition to the forsterite (Mg ₂ SiO ₄ ) crystal phase, monsterite (CaMgSiO ₄ ) having a coefficient of thermal expansion different from the coefficient of thermal expansion of the forsterite crystal phase is included in the insulator layer integrated by firing. Alternatively, at least one crystal phase of akermanite (Ca ₂ MgSi ₂ O ₇ ) is formed, so that the coefficient of thermal expansion of the insulator can be adjusted.

〔Example〕

Next, the composite circuit board with a built-in capacitor of the present invention will be described in detail based on the embodiment shown in FIG.

FIG. 2 is a sectional view showing an embodiment of the composite circuit board with a built-in capacitor of the present invention.

In the figure, 1 is an insulator layer, 2 is a capacitor part, 3
Is a conductor for electric wiring, and the capacitor part 2 is composed of a dielectric layer 4 and an electrode layer 5 alternately laminated.

The insulator layer 1 has the following composition shown in FIG.
Each point of B, C, D and E XYZ A 6036 4 B 46 50 4 C 20 50 30 D 40 30 30 E 60 30 10 However, X, Y and Z are respectively magnesia (MgO) and silica (SiO ₂ ) and weight% of calcia (CaO).

The ceramic raw material powder composed of MgO, SiO ₂ and CaO is mixed so as to fall within the range surrounded by, and the mixture is calcined at a temperature of 1100 ° C. to 1300 ° C. Then, an appropriate organic binder, a dispersant, and a ceramic powder obtained by pulverizing the calcined product,
A mud is formed by adding and mixing a plasticizer and a solvent, and the mud is formed into a sheet by, for example, a conventionally known doctor blade method or the like, and a plurality of obtained green sheets are laminated.

Further, the condenser section 2 forms a slurry by adding and mixing an appropriate organic binder, a dispersant, a plasticizer, and a solvent to a raw material powder of a dielectric material containing BaTiO ₃ as a main component. It is formed into a sheet by a known lifting method or the like. The resulting dielectric green sheet has a predetermined electrode coated on its upper surface with a metal powder such as a silver-palladium (Ag-Pd) alloy and an appropriate solvent, and an alloy paste obtained by adding a solvent thereto by a well-known screen printing method or the like. The electrode layer 5 is formed on the pattern.

In order to conduct the upper and lower surfaces of the insulator layer 1 and the capacitor portion 2, through holes 6 are formed in the insulator and dielectric green sheets by punching or the like. Paste is filled.

Next, the insulator and the green sheet of the dielectric were respectively laminated and thermocompression-bonded, and the obtained laminate was exposed to air at 200 ° C.
The binder is removed at a temperature of 1 to 400 ° C., and then integrated firing is performed at a temperature of 1240 to 1340 ° C. to obtain an insulating substrate having the capacitor unit 2 built therein.

Thus, the conductor pattern for electric wiring is formed on the surface of the insulator layer 1 after the integrally firing by using the Ag-Pd-based alloy paste by screen printing, and if necessary, ruthenium oxide (RuO ₂ ) or the like as a main component. Each of the resistor patterns is printed and formed using the paste, and baked in the air and at a temperature of 850 ° C., whereby a composite circuit board with a built-in capacitor having the resistor 7 is obtained.

When using a paste mainly composed of copper (Cu) for the conductor pattern for electric wiring, use a paste mainly composed of lanthanum boride (LaB ₆ ) or tin oxide (SnO ₂ ) for the resistance pattern. By printing and firing at about 900 ° C. in a nitrogen atmosphere, a composite circuit board with a built-in capacitor similar to that described above is obtained.

 Next, the present invention will be described based on experimental examples.

Mg so that the composition of the insulator layer has the composition ratio shown in Table 1.
Ceramic raw material powders composed of O, SiO ₂ and CaO were mixed, and the mixture was calcined at a temperature of 1100 ° C. to 1300 ° C. Thereafter, the calcined product is pulverized and adjusted to a desired particle size, an appropriate organic binder and a solvent are added to the obtained raw material powder to form a slurry, and the slurry is greened to a thickness of about 200 μm by a doctor blade method. Form the sheet,
Thereafter, the green sheet is subjected to a punching process, and 17
A 0 mm square insulator sheet was obtained.

On the other hand, a ceramic raw material powder containing barium titanate (BaTiO ₃ ) as a main component is mixed with an appropriate organic binder and a solvent to form a slurry, and the slurry is pulled up to set a thickness of a capacitor. 20 μm or more
A green sheet of 60 μm was formed, and thereafter, the green sheet was punched to obtain a 170 mm square dielectric sheet.

Then, about 1 mm to 10 mm using Ag-Pd alloy paste by a thick film printing method such as screen printing on the dielectric sheet.
A corner electrode pattern is printed and formed according to the required capacitance.

Also, a screen printing method or the like is applied to the through holes formed in advance on the insulator sheet and the dielectric sheet.
Fill with Ag-Pd alloy paste.

Thereafter, a plurality of dielectric sheets made of barium titanate are sandwiched between the insulator sheets, thermocompression-bonded, and the resulting laminate is debindered at a temperature of 200 ° C. to 400 ° C. in the air. And fired in the air at the temperatures shown in Table 1.

After checking the presence or absence of a short circuit between the electrode layers of the capacitor part using an LCR meter with the above evaluation sample, JIS C 51
According to the provisions of 02, the LCR meter frequency 1KHz,
The capacitance of the capacitor part is measured under the measurement condition of the input signal level 1.0 Vrms, and the relative dielectric constant (ε _r ) is obtained from the capacitance.
On the other hand, the capacitance at −55 ° C. and 125 ° C. was measured, and the rate of change of the capacitance was calculated as a temperature coefficient (TCC). The insulation resistance value of the capacitor part is the resistance value measured 60 seconds after applying a 25 V DC voltage, and the insulation breakdown voltage is the leakage current value when a voltage is applied between the terminals of the capacitor part at a step-up rate of 100 V per second. Is the voltage value at the moment when the voltage exceeds 1.0 mA.

On the other hand, the crystal layer of the insulator layer was subjected to X-ray diffraction measurement using the evaluation sample, and identified by an X-ray diffraction pattern on the surface of the evaluation sample. The thermal expansion coefficients of the insulator layer and the dielectric layer were 3 mm in length, each having the same composition as the evaluation sample,
A prism-shaped test piece having a width of 3 mm and a length of 40 mm was fired simultaneously with the firing of the evaluation sample, and an average coefficient of thermal expansion in a temperature range of 40 ° C. to 800 ° C. was measured.

 Table 1 shows the above results.

[Effects of the Invention] According to the composite circuit board with a built-in capacitor of the present invention, an insulator layer having excellent high-frequency insulation properties mainly composed of magnesia, silica and calcia and a barium titanate having a high dielectric constant are mainly composed. Since the dielectric material and the dielectric material can be fired and integrated at the same time without reacting with each other, and the thermal expansion coefficients of the insulating layer and the dielectric layer can be made very close to each other, cracks may be formed on the dielectric layer. It is possible to incorporate a capacitor part with high capacitance excellent in insulation resistance and breakdown voltage without causing defects such as defects, and as a result, a miniaturized and high-density capacitor optimal for hybrid substrates etc. A built-in composite circuit board can be obtained.

[Brief description of the drawings]

FIG. 1 is a ternary diagram showing the composition range of the insulator layer of the present invention,
FIG. 2 is a sectional view showing an embodiment of the composite circuit board with a built-in capacitor of the present invention. DESCRIPTION OF SYMBOLS 1 ... Insulator layer 2 ... Capacitor part 4 ... Dielectric layer 5 ... Electrode layer

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masakazu Yasui 1-1, Yamashita-cho, Kokubu-shi, Kagoshima Kyocera Inspector in Kagoshima Kokubu Plant Mitsuru Matsumoto (56) References JP-A-58-17651 (JP, A JP-A-63-295473 (JP, A) JP-A-62-265795 (JP, A) JP-A-1-95591 (JP, A)

Claims (3)

(57) [Claims] 1. A capacitor part is formed by using ceramics containing barium titanate (BaTiO ₃ ) as a main component as a dielectric layer, and providing electrode layers on upper and lower surfaces of the dielectric layer to form a capacitor part. In the composite circuit board with a built-in capacitor sandwiched between the above, the above-mentioned insulator layer has the following A, B, shown in FIG.
Magnesia (Mg) within the range surrounded by each point of C, D, and E
O), a composite circuit board with a built-in capacitor, comprising ceramics containing silica (SiO ₂ ) and calcia (CaO) as main components and containing at least forsterite (Mg ₂ SiO ₄ ) as a crystal phase. Where X, Y, Z
Represents the weight percentage of magnesia (MgO), silica (SiO ₂ ) and calcia (CaO), respectively. XYZ A 60 36 4 B 46 50 4 C 20 50 30 D 40 30 30 E 60 30 10 2. The method according to claim 1, wherein said insulator layer is forsterite (Mg ₂ SiO <sub>2).
4. The</sub> composite circuit board with a built-in capacitor according to claim 1, wherein said composite circuit board contains at least one crystal phase of monticerite (CaMgSiO ₄ ) or akermanite (Ca ₂ MgSi ₂ O ₇ ). 3. The method according to claim 1, wherein said dielectric layer and an insulator layer sandwiching a capacitor portion formed of said dielectric layer and said electrode layer are simultaneously fired. Composite circuit board with built-in capacitor.