JP2010150051A - Magnetic composition, inductor, and substrate for electronic circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode material for low temperature sintering which can be sintered at a low temperature of about 800-850°C, can form a fine thin film which can be used even in a high frequency zone of about 1 GHz, and can be formed by blending components pulverized to a relatively low degree of fineness. <P>SOLUTION: The composition is formed by mixing a ferrite material composed of 40-50 mol% of Fe<SB>2</SB>O<SB>3</SB>, 15-25 mol% of NiO, 5-20 mol% of CuO, and 15-25 mol% of ZnO with 40-79 vol% of glass and 20-50 vol.% of quartz. The glass includes 70-85 wt.% of SiO<SB>2</SB>, 12-25 wt.% of B<SB>2</SB>O<SB>3</SB>, 1-5 wt.% of K<SB>2</SB>O, and 0-8 wt.% of Al<SB>2</SB>O<SB>3</SB>. The magnetic composition has a high content of glass, which aids in sintering at a low temperature and maintaining a stable value of the dielectric constant to a high frequency zone of 1 GHz or more. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnetic composition, an inductor, and an electronic circuit board, and more particularly to a particularly suitable one for use in high-frequency electronic components.

  For example, a chip component such as a multilayer capacitor or a multilayer inductor has a desired internal structure by laminating an insulating film formed of ferrite or the like and a conductive pattern formed in a predetermined pattern using a conductive paste in an appropriate order. A chip body incorporating an internal conductor made of a conductive pattern is manufactured. Thereafter, the chip body is fired to form a chip component.

When the conductive paste is formed from Ag or an Ag alloy, it is necessary to fire at a melting point of Ag (961.93 ° C.) or lower. Therefore, it has been reported that the firing temperature can be lowered (930 ° C. in Patent Document 1) by adding a glass material to the ferrite material as in the invention disclosed in Patent Document 1 and the like.
Japanese Patent Application Laid-Open No. 2002-2521094

  By the way, the development of materials that can be used in a high frequency band is desired as the frequency band used in electronic circuits mounted on electronic devices in recent years increases. However, a conventional chip component using a ferrite material has a magnetic resonance peak of about several MHz, and is not suitable for use in a higher frequency band. In addition, the relative dielectric constant μ corresponding to the magnetic resonance peak also has a certain high value in the low frequency band, but suddenly decreases when it exceeds about 100 MHz, and the target μ cannot be obtained. There is also.

  Furthermore, in the invention disclosed in Patent Document 1, the firing temperature is about 930 ° C., which can be lower than the melting point of Ag. However, there has been a demand for further lowering the firing temperature, and such a demand could not be fully met.

  The present invention solves the above-mentioned problems, and its purpose is to be used for an insulating layer of a laminated type chip component, and has a magnetic resonance peak in the vicinity of 1 GHz and is stable up to a high frequency band near 1 GHz. An object of the present invention is to provide a magnetic composition and an electronic component having a constant μ. Furthermore, a secondary object is to enable low-temperature sintering by setting the firing temperature to 880 ° C. or more preferably 850 ° C. or less.

In order to achieve the above object, the magnetic composition according to the present invention comprises (1) 40 to 50 mol% Fe ₂ O ₃ , 15 to 25 mol% NiO, 5 to 20 mol% CuO, and 15 to 25 mol%. A ferrite material made of ZnO has a composition formed by mixing 40 to 79 vol% of glass having the following composition and 20 to 50 vol% of quartz, and the glass component contains 70 wt% to 85 wt% of SiO ₂ and B _2. O ₃ to 12wt% ~25wt%, 1wt% ~5wt % of _{K 2} O, and a composition distribution satisfying the relationship of 0～8Wt% of _Al 2 _{O 3.} In the present invention, a ferrite material, glass, and quartz are mixed at a desired ratio. Therefore, if the glass component amount is 40 vol%, which is the minimum, quartz can take any value in the range of 50 vol% at the maximum, that is, 20-50 vol%. On the other hand, when the glass component amount is 79 vol% at the maximum, if the minimum amount of quartz is 20 vol%, the ferrite material is 1 vol%, which is also within the scope of the present invention. However, when the amount of the quartz component is 21 vol%, the glass and quartz become 100 vol%, and the ferrite material cannot be mixed. Therefore, in such a case, the component amount of quartz is set to be less than 21 vol%. In practice, at least 1 vol% of the ferrite material is mixed, and in this case, the amount of the quartz component is 20 vol%. Of course, when the glass component is more than 40 vol% and less than 79 vol%, the upper limit of the component amount of quartz is defined so that the component amount of the ferrite material includes a predetermined amount.

  The conventional technical idea of adding a small amount of glass material as a sintering aid to the ferrite material was changed, and the mixing ratio of the glass material was increased. Thereby, the magnetic resonance peak can be moved to a high frequency band near 1 GHz. In order to obtain such an effect, the presence of glass with respect to the ferrite material needs to be equal to or higher. And in this invention, since it contains 20 vol% or more of quartz, if glass is 40 vol% or more, the glass will exist more than a ferrite material. When the ferrite material is mixed with glass and fired, it is melted near the softening point of the glass and liquid phase sintered. At this time, if the glass is 50 vol% or more, the above effect is exhibited because densification is promoted by the surface tension of the glass.

On the other hand, when the ferrite material and the glass having the above composition ratio are mixed (without quartz), if the glass is 80 vol% or more, the corners are rounded when the chip body is formed by the surface tension. Further, it cannot be formed into a desired shape such as a rectangular shape, and foaming occurs inside. Therefore, in the present invention, by combining quartz together, it is possible to make the combined amount of glass and quartz 80% by volume or more, that is, the ferrite material is less than 20% by volume. This is because quartz (crystallized SiO ₂ ) has a high melting point of 1500 ° C., and the firing temperature assumed by the present invention (for example, about 900 ° C., which is a low temperature below the melting point of Ag, further 850 to 800 ° C.). Does not foam or dissolve. Therefore, quartz (crystallized SiO ₂ ) plays the role of an aggregate, and even if the amount of the ferrite material is less than 20 vol%, chip deformation (corner roundness) does not occur. Further, since the glass component amount is 79 vol% or less, foaming does not occur during firing. Since the density decreases when foamed, the relative density, which is the ratio of the actual density to the ideal density, is obtained, and it can be determined that a relative density of a certain value (for example, 90%) or more is effective. it can. Further, if the relative density is 90% or more, the moisture absorption resistance and strength of the material are improved, and there is no hindrance to practical use. Furthermore, combined with an increase in the glass abundance ratio, the firing temperature can be lowered and the temperature can be set to about 800 to 850 ° C. Of course, the firing temperature does not prevent firing at the above temperature range.

  And as a result of actually baking the magnetic composition manufactured by changing the composition ratio of glass, quartz and ferrite materials as appropriate, it was confirmed that the above range was effective. Furthermore, the critical meaning of the upper and lower limits for each composition seems to be as follows.

  (2) Further, the ferrite material is preferably added at 10 vol% or more. That is, as described above, if a ferrite material is added even a little, the ferrite material has a constant dielectric constant that is higher than that of a ferrite material that is not added. And since the relative dielectric constant maintains substantially the same value even in a high frequency region of 1 GHz or higher, it may be added in the present invention, but more preferably, the amount of the ferrite material is 10 vol% or higher. is there. In this way, the relative dielectric constant is about 1.2 to 1.3. Therefore, it is possible to apply to inductance, and it is preferable because usable target products and application fields are widened.

  (3) The inductor and the electronic circuit board according to the present invention are configured using the magnetic composition described in the above (1) or (2). Here, the inductor is a multilayer inductor (multilayer chip inductor), and is used for a chip body incorporating a coil made of a conductor pattern. This chip body is configured by laminating sheet-like magnetic compositions. Further, the electronic circuit substrate can be realized as, for example, a LTCC (Low Temperature Co-fired Ceramic) multifunctional substrate.

  In the present invention, a magnetic resonance peak is provided in the vicinity of 1 GHz, and a constant magnetic permeability can be stably provided up to a high frequency band near 1 GHz. Furthermore, the firing temperature can be 850 ° C. or lower. Moreover, the amount of the ferrite material component can be reduced to less than 20 vol%, and accordingly, the magnetic resonance peak (frequency at which the magnetic permeability starts to decrease) can be positioned at a higher frequency.

Hereinafter, preferred embodiments of the present invention will be described. The magnetic composition according to the present invention is formed by mixing a predetermined ferrite material with 40 to 79 vol% glass and 20 to 50 vol% quartz. Ferrite material, 40~50mol% of _Fe 2 _O 3, 15~25mol% of NiO, 5 to 20 mol% of CuO, using those within the composition range of 15 to 25% of ZnO. Further, the glass has a composition distribution satisfying the relationship of 70 wt% to 85 wt% of SiO ₂ , 12 wt% to 25 wt% of B ₂ O ₃ , 1 wt% to 5 wt% of K ₂ O, and 0 to 8 wt% of Al ₂ O _3. And

  This magnetic composition can be manufactured, for example, by the steps shown below. That is, a predetermined amount of each raw material component of the ferrite material is weighed and calcined according to a known ferrite material manufacturing process. This calcined ferrite material (within the above composition range), glass and quartz formed in the above composition range are mixed in a ball mill pot. At this time, the glass is weighed so as to be 40 to 79 vol% and quartz is 20 to 50 vol% (however, the total of both is less than 100 vol%, preferably 99 vol% or less).

  Next, a predetermined amount of alcohol such as ethanol is weighed and put into a ball mill pot into which the above ferrite material, glass and quartz are mixed and charged. Then, it is mixed and ground for about 20 hours in the ball mill. The particle size (D50) of the powder after pulverization is about 0.8 μm. This powder is further pulverized with a mortar or the like. A sheet-like magnetic composition is produced by mixing the pulverized powder and a binder such as ethyl cellulose and performing sheet forming.

  As one embodiment of the electronic component (multilayer inductor) according to the present invention, it can be manufactured using the sheet-like magnetic composition formed as described above. That is, a predetermined number of the sheet-like magnetic compositions are laminated. During this lamination process, a conductor pattern for forming a coil is printed on the surface of the sheet-like magnetic composition exposed at that time. Thereby, the laminated body which has a coil which consists of predetermined number of turns inside is formed.

While heating this laminated body at a desired temperature (for example, about 50 ° C.), the laminated body is pressurized at a desired pressure (for example, 1 t / cm ² ), and a sheet made of the laminated magnetic composition is pressure-bonded. Thereafter, the chip body is manufactured by cutting into a predetermined shape. The chip body is fired at a predetermined temperature, the surface of the obtained sintered body is barrel-polished, an external terminal electrode is attached to a predetermined portion, and baking is performed, whereby a multilayer inductor is manufactured. Of course, it can also be manufactured by other manufacturing methods. Moreover, although it is a calcination temperature at the time of baking a chip body, it can be set to 800 to 850 degreeC. Of course, firing at a higher temperature (such as 880 ° C.) is not a problem.

1 and 2, the inductance value and Q frequency characteristic of the multilayer chip inductor manufactured according to the above manufacturing process were measured. The chip size of the manufactured sample was 0.6 × 0.3 × 0.3 mm. The component amounts of the sample of the embodiment of the present invention were 7.5 vol% for the ferrite material, 42.5 vol% for the glass, and 42.5 vol% for the quartz. The composition ratio of ferrite material is
Fe ₂ O ₃ : 50 mol%
NiO: 25 mol%
CuO: 5 mol%
ZnO: 20 mol%
And the composition ratio of glass is
SiO ₂ : 70 mol%
B ₂ O ₃ : 18 mol%
K ₂ O: 4 mol%
Al ₂ O ₃ : 8 mol%
It was. Moreover, the sample as a comparative example used the alumina sendust generally used as a dielectric material for inductors (the dimension shape is the same).

  As shown in FIG. 1, the inductance value (L value) is about 15% higher in the product of the present invention. As shown in FIG. 2, the Q value of the dielectric material of the comparative example is about 10% higher. Therefore, in consideration of these characteristics, it may be applied to an appropriate part or the like.

  In addition, the use of the magnetic composition according to the present invention is not limited to this multilayer inductor, and it can be applied to other applications as long as the dielectric constant in the high frequency range to be used is satisfied. is there. Furthermore, since this magnetic composition has a low firing temperature and a stable dielectric constant up to a high frequency range, it can also be used as a material for LTCC (Low Temperature Co-fired Ceramic) multifunctional substrates. it can. That is, the present invention can be applied not only to elements for configuring electronic circuits such as so-called inductors and capacitors as electronic components, but also to substrates for configuring such electronic circuits.

Next, in order to verify the effect of the present invention, a plurality of samples were manufactured by changing the composition, and the magnetic permeability μ and the relative density were obtained for each sample. Each sample is formed into a sheet according to the above-described manufacturing process of the magnetic composition, and then a predetermined number of the sheets are laminated to form a laminate. In this experiment, since the magnetic composition itself is evaluated, the conductor pattern is not printed as in the electronic component described above. And while heating this laminated body at the temperature of desired temperature (for example, about 50 degreeC), it pressurizes with a desired pressure (for example, 1 t / cm < ² >), and crimps | bonds the sheet | seat which consists of the laminated | stacked magnetic composition. Next, the pressure-bonded laminate was cut into a ring shape and then fired at a predetermined temperature. The firing temperature was 800 ° C. Winding was applied to the sintered body of the ring-shaped magnetic composition for 10 turns, and μ ′, μ ″ and the like were measured.

  Samples were prepared by appropriately combining 12 types of ferrite materials A to L shown in Table 1 and 13 types of glasses A to M shown in Table 2.

(Examples 1 to 11)
As shown in Table 3, 11 types of samples with appropriate changes in composition were prepared. In these 11 types of samples, at least one of the raw materials has a boundary point (near the boundary point) that defines the range of the composition ratio of the present invention. In either case, the relative density is 90% or more. became. Of course, the edge (corner part) of the ring-shaped sintered body as a sample is not rounded. Further, the magnetic permeability μ is an initial magnetic permeability. In this measurement, the inductance value and series resistance value of the ring-shaped magnetic composition with the windings were measured with an impedance analyzer, and μ ′ and μ ″ were calculated from the measured values.

  As will be described later, the magnetic composition within the composition ratio range constituting the present invention has a magnetic resonance peak of about 1 GHz, and the frequency characteristic of the magnetic permeability is the value of the initial magnetic permeability up to a high frequency band of about 1 GHz. Therefore, the value of the initial permeability described in Table 3 can be estimated as the permeability under the actual use environment in the high frequency range as it is.

(Comparative Examples 1-21)
On the other hand, as a comparative example, at least one of the raw materials was prepared having a value (near the boundary point) that deviates from the boundary point that defines the range of the composition ratio of the present invention. A sample out of the scope of the present invention (comparative example) has a relative density of less than 90% and rounds the edge of the sample. Therefore, it was confirmed that it is not suitable for use as an electronic component.

  Moreover, although not described in the table, a sample consisting of another combination was prepared and evaluated, and the same tendency was observed.

It is a graph which shows the frequency characteristic about the inductance value of the chip inductor in this invention goods and a comparative example. It is a graph which shows the frequency characteristic about Q value of the chip inductor in this invention goods and a comparative example.

Claims (4)

A ferrite material composed of 40-50 mol% Fe ₂ O ₃ , 15-25 mol% NiO, 5-20 mol% CuO, 15-25 mol% ZnO, 40-79 vol% glass having the following composition, and 20 quartz. A composition formed by mixing ˜50 vol%,
The glass component has a composition distribution satisfying a relationship of 70 wt% to 85 wt% of SiO ₂ , 12 wt% to 25 wt% of B ₂ O ₃ , 1 wt% to 5 wt% of K ₂ O, and 0 to 8 wt% of Al ₂ O _3. A magnetic composition characterized in that   The magnetic composition according to claim 1, wherein the ferrite material is added in an amount of 10 vol% or more.   The inductor comprised using the magnetic composition of Claim 1 or 2.   An electronic circuit board configured using the magnetic composition according to claim 1.

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