JPH07192905A - Composite functional element - Google Patents

Abstract

PURPOSE:To inhibit the mutual diffusion of a composition having an adverse effect on each electrical characteristic by forming the single body of Pt, Pd or Ag on the semiconductor porcelain side in the vicinity of the jointing section of a magnetic substance ceramic and a semiconductor ceramic or one layer or more of the alloy metallic layers of Pt, Pd or Ag such as an Ag-Pd alloy. CONSTITUTION:A metallic pattern 2a consisting of conductive paste is printed on a varistor sheet 1b, and a metallic pattern 2b is printed similarly on a varistor sheet 1c and a metallic pattern 2c on a varistor sheet 1d. A metallic pattern 2d composed of conductive paste is printed on a ferrite sheet 3b. These printed varistor sheets 1a, 1b, 1c, 1d and ferrite sheets 3a, 3b are laid over and contact- bonded. Accordingly, no layer peeling due to the difference of shrinkage factors and delamination is generated. The mutual diffusions of compositions having an adverse effect on each electrical characteristic can be inhibited.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-functional device having both varistor characteristics, capacitor characteristics and magnetic characteristics.

[0002]

2. Description of the Related Art A semiconductor device such as an IC may be destroyed or malfunction due to transient noise such as static electricity. As a method of preventing these noises, a set or a ground of the board is set, or an element array in the board or a noise absorbing element such as a varistor or an LC filter is used.

Of these, the method of using an element such as a varistor is relatively simple and is often performed as a measure against noise. For the purpose of protection from these noises,
The varistor voltage needs to be as close to the circuit voltage as possible, and it is desired to reduce the voltage. Further, a chip-type component having a small element size and capable of surface mounting is desired due to miniaturization of the device.

[0004]

An electronic component which addresses these problems is disclosed in Japanese Patent Publication No. 58-23921. However, the electronic component described in Japanese Patent Publication No. 58-23921 has the same limiting voltage as that of the conventional varistor, and further voltage suppression capability is required for circuit protection.

Also, in order not to generate noise from various devices or to prevent noise from entering various devices,
Ferrite chips and capacitors are attached to the input / output parts of each device to prevent electromagnetic noise, but adding these parts requires many parts, increasing the board area and complicating the process. However, there is a problem in that it leads to cost increase.

Therefore, a semiconductor device having a varistor characteristic and a magnetic substance porcelain are joined and integrated to provide a multi-functional device which solves the above-mentioned problems. However, when this multi-functional element is integrally sintered, there is a problem that the respective characteristics are deteriorated due to the mutual diffusion of the respective materials.

The object of the present invention is to suppress the mutual diffusion of each material caused by joining a semiconductor porcelain and a magnetic porcelain, and to integrate them as a ferrite chip and a capacitor without impairing their electrical characteristics. , To provide a multi-functional element as a component for electromagnetic noise suppression.

[0008]

The invention according to claim 1 is
In a multifunctional device obtained by joining a semiconductor ceramic having varistor characteristics and a magnetic ceramic made of a magnetic material and integrally sintering the semiconductor ceramic portion, the semiconductor ceramic portion near the junction between the semiconductor ceramic portion and the magnetic ceramic portion. This is a multi-functional device having one or more metal layers on its side.

In the invention according to claim 2, the metal layer is Pt, P
It is a simple substance of d or Ag or an alloy of Pt, Pd, and Ag.

[0010]

By providing one or more layers of Pt, Pd, Ag alloy metal layers such as Pt, Pd, Ag alone or Ag-Pd alloy on the semiconductor ceramic side near the junction between the magnetic ceramics and the semiconductor ceramics. It is possible to suppress the mutual diffusion of the composition, which adversely affects the respective electric characteristics. In addition, the metal layer can reduce stress generated in a joint portion of different materials, and can suppress layer peeling.

[0011]

【Example】

[Preparation of Varistor Material] As raw materials, ZnO, Bi ₂ O ₃ , CoCO ₃ , MnO ₂ and Sb ₂ O ₅ having a purity of 99% or more are used.
Were weighed in proportions of 98 mol%, 0.5 mol%, 0.5 mol%, 0.5 mol% and 0.5 mol% respectively, and pure water was added thereto and mixed by a ball mill for 24 hours to obtain a mixture slurry. Got Next, the obtained slurry was filtered, dried, granulated, and then calcined at a temperature of 800 ° C. for 2 hours.

Further, the calcined product was coarsely crushed, pure water was added, and finely crushed with a ball mill. After filtering and drying this slurry, it was dispersed in a solvent together with an organic binder to obtain a slurry. A sheet having a thickness of 50 μm was prepared from the obtained slurry by the doctor blade method. This sheet was punched out to obtain a plurality of green sheets.

[Preparation of Ferrite Material] Fe ₂ O ₃ , NiO, and ZnO each having a purity of 99% or more are used as raw materials.
7 mol%, 30 mol% and 23 mol% were weighed, pure water was added and mixed by a ball mill for 24 hours to obtain a mixture slurry. The resulting slurry was filtered, dried, granulated, and then calcined at a temperature of 1100 ° C. for 2 hours.

Further, after roughly calcining the calcined product, Bi
Add ₂ wt% of O ₃ and add pure water and add 24 with a ball mill.
Mixed and crushed for hours. After filtering and drying this slurry, it was dispersed in a solvent together with an organic binder to obtain a slurry.
50μ from the obtained slurry by the doctor blade method
A sheet having a thickness of m was prepared. Punch this sheet,
Multiple green sheets were obtained.

[Printing / Laminating / Firing Internal Electrodes] As shown in FIG. 1, the varistor sheet 1a obtained in the above steps,
1b, 1c, and 1d were prepared, and the ferrite sheets 3a and 3b were prepared. Then, the varistor sheet 1b was printed with a metal pattern 2a made of a conductive paste, the varistor sheet 1c was similarly printed with the metal pattern 2b, and the varistor sheet 1d was similarly printed with the metal pattern 2c.

A metal pattern 2d made of a conductive paste was printed on the ferrite sheet 3b. The conductive paste used was silver and palladium in a ratio of 7: 3. The varistor sheet 1a and the ferrite sheet 3a are dummy sheets on which no metal pattern is formed. The conductive paste was printed by a screen printing method.

Further, these printed varistor sheets 1a, 1b, 1c, 1d and ferrite sheets 3a, 3 are used.
b were stacked in the order shown in FIG. 1 and pressure-bonded at a pressure of ² t / cm ² . The pressure-bonded body thus formed was cut into a predetermined size and fired at 950 ° C. for 2 hours to obtain a composite functional element body. FIG. 2 is a laminated sectional view of the composite functional element body 4.

Further, as shown in FIG. 3, a silver paste was applied to the obtained element body 4 and heat-treated at 800 ° C. for 10 minutes to form an external electrode 5 and an earth electrode 6. As the metal pattern 2c, other than Ag-Pd paste, those using Ag, Pt, etc. as shown in Table 1 were also prepared and used as samples for the following characteristic test. Further, a sample having two metal layers arranged as shown in FIG. 4 was also prepared as a measurement sample. In the appearance of the device obtained by the above method, no layer peeling or delamination due to the difference in shrinkage was observed.

[0019]

[Table 1]

The samples thus obtained were evaluated for varistor voltage, nonlinear coefficient, capacitance, dielectric loss, inductance and impedance. The test method will be described below. As the varistor voltage, the voltage obtained for a direct current of 1 mA was measured. The non-linear coefficient (α) was obtained from the following formula from the voltage (V _1mA ) obtained for a direct current of 1 _mA and the voltage (V _{10 mA} ) obtained for a direct current of 10 mA. α = 1
/ Log ( _V10mA / _V1mA ).

Next, a DC voltage of 15 V was applied for 2 minutes to measure the insulation resistance at 25 ° C., and the capacitance and dielectric loss were measured at a frequency of 1 MHz and 1 Vrm using an automatic bridge type measuring instrument.
s, measured at 25 ° C. Inductance is frequency 1MH
It was measured at z, 1 Vrms, and 25 ° C. Impedance is a resistance value at a frequency of 100 Mhz. The results of these characteristics are shown in Table 2.

[0022]

[Table 2]

As described above, by forming the metal layer on the semiconductor porcelain side near the junction between the semiconductor porcelain having the varistor characteristics and the magnetic porcelain, the dielectric loss is reduced and the inductance is increased. The reason for the improvement in the characteristics is that the diffusion of both elements, particularly the diffusion of Ni or Fe elements from ferrite was suppressed by the metal layer. The metal layer is A
It may be a single substance of g, Pt, Pd, or an alloy such as Ag-Pd.

[0024]

According to the present invention, even when a semiconductor porcelain having varistor characteristics and a magnetic porcelain made of ferrite are compounded, mutual diffusion of each composition is suppressed by the metal layer, and the electrical characteristics of each composition are impaired. It is possible to form an element having a composite function. Further, such a metal layer also has an effect of relieving stress during sintering of each composition, and can prevent layer peeling and delamination.

By combining a semiconductor porcelain having varistor characteristics with a magnetic porcelain made of ferrite, a small element for protection against electromagnetic noise including transient noise can be obtained. Furthermore, by integrally sintering, the process can be simplified, and a smaller and cheaper element can be obtained.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a composite function element of the present invention.

FIG. 2 is a cross-sectional view of a multifunctional device according to the present invention.

FIG. 3 is a perspective view of a composite functional element body of the present invention.

FIG. 4 is an exploded perspective view of another example of the composite function element of the present invention.

[Explanation of symbols]

 1a, 1b, 1c, 1d Varistor sheet 2a, 2b, 2c, 2d Metal pattern 3a, 3b Ferrite sheet 4 Complex functional element 5 External electrode 6 Earth electrode

Claims (2)

[Claims] 1. A composite function element obtained by joining a semiconductor porcelain having varistor characteristics and a magnetic porcelain made of a magnetic material and integrally sintering the porcelain, and in the vicinity of a joint between the semiconductor porcelain and the magnetic porcelain. 2. A multi-function device characterized in that one or more metal layers are provided on the semiconductor porcelain side. 2. The multi-function device according to claim 1, wherein the metal layer is Pt, Pd, or Ag alone or an alloy of Pt, Pd, and Ag.