JPH10303027A - Multilayer microwave induction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an electric field between the adjacent coil-like lines not uniform so as to reduce the potential difference between the coil-like lines and reduce the capacitive component by making the cross-section of the coil-like line flat and its surface protruding. SOLUTION: The cross-section of a coil-like line 2 is made flat and substantially oval and a stray capacitance between the adjoining coil-shaped lines 2 is reduced by end face effects. The coil-like line 2 is formed accurately with excellent reproducibility by previously forming a recessed part on a conductor line forming part on an insulating layer, printing a paste conductor of a metal material having a high conductivity, such as Ag and Cu. The insulating layer is formed of a green sheet composed of a dielectric whose major component is a magnetic body that can be sintered at a low temperature, such as Ni-Zn based ferrite, and AlO. At the time of forming the recessed part, the green sheet is heat-pressed to make the thickness uniform. Thus, the stray capacitance and its variation are reduced without deteriorating the performance of a microwave induction device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a VHF band, a UHF band,
The present invention relates to a laminated microwave induction element used in a high frequency band such as a band and a microwave band.

[0002]

2. Description of the Related Art A laminated microwave induction element is an induction element integrally sintered by a lamination technique and is particularly suitable for use in a high frequency such as a microwave band. This laminated microwave induction element is used as an inductor, used as a filter in combination with a capacitive element, or used as a transformer using mutual induction by adding a conductor line on the secondary side. , UHF
It is used in various parts of mobile communication devices typified by mobile phones and car phones utilizing a high frequency band such as a band and a microwave band.

[0003] Various kinds of laminated microwave induction elements as described above have been proposed in the past. A first conventional example is a laminated inductor formed by a thick film printing method. FIG. 3 is a partially transparent perspective view of the multilayer inductor, and FIG. 4 is a cross-sectional view of the multilayer inductor. The structure of the multilayer inductor will be described with reference to FIGS. In all the drawings, the same reference numerals are given to parts having the same function. This laminated inductor is formed by laminating a plurality of insulator layers (1) such as a magnetic material or a dielectric material on the surface of which a conductor line (2) is formed by a thick film printing method or the like, and the conductor line is an insulator layer (1). A coiled line that is electrically connected and circulated through a through-hole (not shown) provided in the above is formed. After sintering the thus obtained laminate, an external terminal (3) is formed by applying or printing a conductive paste or the like on the outer periphery of the laminate and baking.

As a second conventional example, Japanese Patent Publication No.
There is a multilayer inductor described in Japanese Patent Application Laid-Open Publication No. 1 (1999). This structure will be described with reference to the sectional view of FIG. In this conventional example, at least most of the vertically adjacent portions of the conductor line (2) are arranged so as to be hardly different from each other.

As a third conventional example, Japanese Patent Application Laid-Open No. 05-006
No. 823 discloses an inductor. This structure will be described with reference to the sectional view of FIG. In this conventional example, a low dielectric constant dielectric layer (4) is formed around the conductor line (2).

[0006]

Since the inductor of the first prior art has a structure in which the conductor line forms a coil that circulates in the stacking direction, the capacitance between the conductor lines adjacent to each other in the stacking direction via the insulating layer (ie, the capacitance ( A stray capacitance C _f ) is formed. The stray capacitance C _f is determined by the area S of the overlapping portion of the conductor lines facing each other between the insulating layers and the distance d between the conductor lines facing each other between the insulating layers.
And the relative dielectric constant ε _r of the insulator layer.

[0007] Formula 1 is a relational expression that represents the stray capacitance C _{f. C f = ε o · ε r} · S / d ( Equation 1) where epsilon _o is the dielectric constant in vacuum.

In general, the first conventional inductor is equivalently formed as a parallel resonance circuit, and its self-resonant frequency _fr is
Represented by the inductance L and the stray capacitance C _f. Equation 2 is a relational expression representing the self-resonant frequency f _{r. fr} = 1 / (2.pi. ( _L.Cf ) ^1/2 ) (Equation 2)

[0009] The inductor used in a high frequency band such as a microwave band, at least the self-resonant frequency f _r does not fulfill the function as parts to be higher than the frequency used in the inductor. Therefore, it is necessary that both the induction component and the capacitance component are small.

[0010] However, the first conventional example in structural as conductor lines are widely smoothly formed, a large stray capacitance C _f is generated, the self-resonant frequency f _r appears on the lower frequency side than the frequency used. The rate of change in the stray capacitance C _f is directly affect the self-resonant frequency f _r, varies with the also electric properties. As described above, there are various problems that are not suitable for use at high frequencies, and it is necessary to reduce the stray capacitance _Cf and reduce its variation.

In the multilayer inductor described in the second conventional example, the conductor lines adjacent in the stacking direction are staggered,
It proposes to reduce the stray capacitance C _f in question in the first conventional example by reducing the area S of the conductor lines facing the layers. However, arranging the conductor lines in a staggered manner increases the arrangement area of the conductor lines, thereby increasing the external dimensions of the components, increasing the leakage magnetic flux, and increasing the area through which the magnetic flux passes (the effective cutting distance). The characteristics of the inductor were remarkably inferior, for example, the area) was reduced and the inductance was reduced. Furthermore, it is ineffective as a means for suppressing the C _f variation of the stray capacitance.

In the inductor described in the third conventional example, a conductor line is printed with a conductive paste to which a diffusing agent for forming a dielectric layer having a low dielectric constant is added, and the dielectric layer having a low dielectric constant is sintered at the time of sintering. By forming (4) around the conductor line, the dielectric constant ε _r of the insulator layer between the conductor lines is reduced, and the stray capacitance C _f
Is proposed. However, it is extremely difficult to form a low dielectric constant dielectric layer around the conductor line with good reproducibility and it is easy to induce structural defects such as delamination.
Also have a significant adverse effect on the conductivity of the conductor lines is evident that further variations of the stray capacitance C _f is very large, it was almost proposed no reality.

[0013] As described above, suitable for use in a high frequency band, such as a conventional microwave band, that is, stray capacitance C _f small, the variation was not also small laminated microwave inductive element. SUMMARY OF THE INVENTION An object of the present invention is to provide a laminated microwave induction element which solves the above-mentioned problems of the prior art, easily reduces both stray capacitance _Cf and its variation, and is suitable for use in a high frequency band such as a microwave band. That is.

[0014]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have conceived of a laminated microwave induction device having a remarkably improved structure. That is, the first invention is a laminated body obtained by laminating and integrally sintering a plurality of sheets made of an insulator having a conductor line formed on the surface, wherein the conductor line is formed on an edge of the sheet made of the insulator or on the sheet. A laminated microwave induction element that is electrically connected through a provided through hole to form a coiled line that circulates, wherein the cross-sectional shape of the coiled line is flat, and This is a laminated microwave induction element having a convex surface.

The coil-shaped line having a flat cross-section and a convex surface is a coil-shaped line having a deformed elliptical cross-section as shown in FIG.

According to a second aspect of the present invention, there is provided a laminated body obtained by laminating and integrally sintering a plurality of sheets of an insulator having a conductor line formed on a surface thereof, wherein the conductor line is formed on an edge of the sheet made of the insulator or on the sheet. A laminated microwave induction element that is electrically connected through a provided through hole to form a coiled line that circulates, wherein the cross-sectional shape of the coiled line is flat, and One surface is a laminated microwave induction element having a convex surface and a concave surface facing the opposite surface.

The coil-shaped line having a flat cross-sectional shape, a convex surface on one side, and a concave surface on the opposite side has a deformed U-shaped cross-section as shown in FIG. It is a coiled line.

According to the first and second aspects of the present invention, the electric field between adjacent coiled lines is made non-uniform by making a part or the whole of the surface of the coiled line non-uniform. Since the potential difference between them is reduced to reduce the capacitance component (edge effect), the cross-sectional shape may not be symmetrical as shown in FIGS. 7 and 8, for example, and a part of the surface may be flat. May be, a part of the convex surface may be a concave portion, there may be a slight burr at the end in the width direction of the cross section, or even if the end is cut off, The effect does not change.

The thickness t and the width W of the cross section of the coiled line
If the flatness, which is the ratio W / t, is small and not flat, the stray capacitance _Cf is small and causes no practical problem. Conversely, if the flatness is large and too flat, the effect of the invention is small because the end face effect is weak. Is preferably 2 to 30. More preferably, it is 7.5 to 20.

If the cross-sectional area A determined by the thickness and width of the coil-shaped line is small, the resistance component increases and the loss increases. If the cross-sectional area A is large, the effect of the invention is small because the end face effect is small. t.W / 2 or more, t.W-0.
It is preferably less than 215 · t ² .

Further, the distance d that the coiled line is adjacent to each other across an insulating layer is larger than the shortest distance d ₀ is preferable to increase the width direction, more preferably at least adjacent the t / 2 inward from the end face portion , T−t ² / W + d ₀ or less.

[0022]

As a result of various trials in the research, it is necessary that the cross section of the end of the coil-shaped line is an ellipse having a smaller radius of curvature than the circular arc contacting the upper and lower surfaces. On the other hand, it has been found that the end face cross section is more rounded than the rhombus, that is, it is desirable that the diagonal length of the rhombus is larger than the rhombus corresponding to the width W and the thickness t. . Here, the cross-sectional area a of the ellipse is a = t · W−0.215 · t ² , and the cross-sectional area b of the rhombus is b> t · W / 2 and a> b. desirable. It has been found that the shape is most ideally an ellipse having a major axis W and a minor axis t.
Based on such knowledge, the present invention was implemented.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION An outline of a laminated microwave induction device according to the present invention will be described by taking an inductor as an example. FIG. 1 is a partially transparent perspective view of the same, and FIG. 2 is an ABCD section thereof.

This inductor comprises an insulator layer (1), a coiled line (2) having a substantially elliptical cross section, an external terminal (3) formed at a leading end of the coiled line, and a through hole (not shown). ).

[0025] In the present invention, the cross-section of the coiled line (2) is a flat substantially oval, thereby reducing the stray capacitance C _f between the coiled lines adjacent the end surface effects. The coil-shaped line (2) having a flat cross section and a substantially elliptical shape is formed by forming a concave portion in advance in the conductor line forming portion of the insulator layer, and then depositing a metal material having high conductivity, such as Ag or Cu, on the concave portion. The printed conductor is precisely formed with good reproducibility. The insulating layer is formed of a green sheet made of a magnetic material such as a Ni—Zn ferrite that can be sintered integrally with the metal material, for example, a low-temperature sinterable material, or a dielectric mainly composed of Al ₂ O ₃ . When forming the concave portion, the thickness of the green sheet is made uniform by heating and pressing. In this way, the stray capacitance _Cf and its variation are reduced without reducing the performance of the microwave induction element.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the laminated microwave induction device according to the present invention will be described in detail. Example is 800 MH
An inductor whose impedance at z is 50 ohms.

(Example 1) First, a dielectric green sheet containing Al ₂ O ₃ as a main component was prepared for about 0.1 by a doctor blade method.
After being formed to have a thickness of mm, it was cut into a predetermined outer size. The green sheet was affixed to a stainless steel frame having a positioning groove and having a central portion slightly smaller than the outer shape of the green sheet and cut into a square.

Thereafter, the green sheet is processed while being attached to a stainless steel frame. Therefore, a description of the stainless steel frame is omitted until the following state changes. Hereinafter, the positioning groove provided in the stainless steel frame is used as a processing reference.

The green sheet is about 0.1 m in diameter.
It was arranged in a mold having a punching pin of m and punched out to form a through hole. The green sheet was placed in a mold having a projection having the same shape as the conductor line pattern. The mold is set at 80 ° C so that the green sheet has appropriate flexibility.
To 120 ° C. The green sheet is pressurized at a pressure of 0.5 kg / cm ² to 1 kg / cm ² , and a concave portion having a U-shaped cross section and a surface shape of a conductor line pattern is formed on one surface of the green sheet to a depth of about 0.03 mm.
Transcribed.

Next, the green sheets were placed on a work table of a printing machine capable of printing with good reproducibility and precision. The work table is provided with a suction mechanism so that almost the entire surface of the green sheet is sucked to prevent the green sheet from being bent or distorted. From above the concave portion of the green sheet, the Ag paste was about 0.008 mm thick and about 0.09 mm wide, and about 0.008 mm thick, about 0.17 mm wide and further about 0.008 mm thick. Printing was performed with a width of about 0.09 mm to form a substantially elliptical conductor line. The paste is suction-filled into the through-hole simultaneously with printing by the suction mechanism.

After drying a plurality of green sheets on which the conductor line pattern is printed, the green sheets are punched out of a stainless steel frame, and superposed from 100 ° C. so as to form a 2.5-turn coiled line (2) around which the conductor lines circulate. It heat-pressed at 140 degreeC. Next, the outer dimensions after sintering are 3.2 mm.
It was cut to a size of × 1.6 mm and sintered. Thereafter, a conductor paste containing Ag as a main component was applied to the outer peripheral portion of the sintered body, and a conductor external electrode (3) was formed and baked to obtain an inductor of this example. This embodiment is an embodiment in which the flatness of the coiled line is set to 7.5. In addition, samples having an oblateness of 2, 20, and 30 were also manufactured.

Example 2 A green sheet having a concave portion prepared in the same manner as in Example 1 was placed on a printing table of a printing press. An Ag paste was printed on the concave portion of the green sheet at a thickness of about 0.024 mm and a width of about 0.17 mm to form a substantially U-shaped conductor line pattern. Hereinafter, since it is the same as the first embodiment, the description thereof is omitted.

(Comparative Example) A sample of the first conventional example was prepared for comparison with the embodiment according to the present invention. In the comparative example,
A thickness of about 0.0 on a green sheet with no recess
Ag paste was printed at a width of 24 mm and a width of about 0.17 mm to form a rectangular conductor line. The other parts are the same as those of the first and second embodiments, and the description thereof will be omitted.

The resonance frequency at which the impedance of the inductor thus obtained becomes infinite was measured by a vector network analyzer. Table 1 shows the results.

[0034]

[Table 1]

In Table 1, samples having different oblate ratios are distinguished by numbers 1 to 4. Further, the ratio of the resonance frequency in the table, the resonance frequency f _r of the example sample ', represented by the resonance frequency f _r of the comparative _sample, f _r' is / f _r. The resonance frequencies of the inductors of Examples 1 and 2 of the present invention were about 1.02 times to about 1.18 times respectively as compared with the inductor of the comparative example. In addition, the variation of the resonance frequency increased from about 0.6 times to about 0.7 times the comparative example.

In these embodiments, the coiled line is formed by arranging the conductor lines so as to wrap around in the stacking direction, but a meander line or a spiral line in which the conductor lines are arranged on the same layer. Stray capacitance C _f generated between adjacent capacitor patterns and ground patterns
Can be reduced by the end face effect, so that the effect of the present invention does not change.

[0037]

According to the present invention, it is possible to provide a laminated microwave induction element suitable for use in a high frequency band such as a microwave band by easily reducing both the stray capacitance and its variation.

[Brief description of the drawings]

FIG. 1 is a partially transparent perspective view of a laminated microwave induction device according to one embodiment of the present invention.

FIG. 2 is an ABCD sectional view according to one embodiment of the present invention.

FIG. 3 is a partially transparent perspective view of a first conventional example.

FIG. 4 is an ABCD sectional view of a first conventional example.

FIG. 5 is an ABCD sectional view of a second conventional example.

FIG. 6 is an ABCD sectional view of a third conventional example.

FIG. 7 is a sectional view of a coiled line according to the present invention.

FIG. 8 is another sectional view of the coiled line according to the present invention.

[Explanation of symbols]

 1 green sheet, 2 conductor lines

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshihiko Tanaka 70-2 Minamisakae-cho, Tottori City, Tottori Pref.

Claims (6)

[Claims] 1. A laminated body obtained by laminating and integrally sintering a plurality of sheets of an insulator having a conductor line formed on the surface, wherein the conductor line is provided on an edge of the sheet of the insulator or on the sheet. A laminated microwave induction element electrically connected through a through-hole to form a circling coiled line, wherein the coiled line has a flat cross-sectional shape, and the surface of the coiled line is convex. A laminated microwave induction element characterized by being formed so that: 2. A laminated body obtained by laminating and integrally sintering a plurality of sheets of an insulator having a conductor line formed on the surface, wherein the conductor line is provided on an edge of the sheet of the insulator or on the sheet. A laminated microwave induction element electrically connected through a through hole to form a circling coiled line, wherein the coiled line has a flat cross section and one surface of the coiled line is convex. Wherein the opposed portion is concave. 3. When the thickness of the thickest portion of the cross section of the coiled line is t and the width is W, the oblateness X represented by X = W / t is 2
3. The multilayer microwave induction device according to claim 1, wherein the value falls within a range of ≦ X ≦ 30. 4. 4. When the thickness of the thickest portion of the cross section of the coil-shaped line is t and the width is W, an oblateness X represented by X = W / t is expressed by:
The multilayer microwave induction device according to claim 1, wherein the range is 7.5 ≦ X ≦ 20. 5. The method according to claim 1, wherein an area A of the cross section of the coiled line is in a range of (tW / 2) ≦ A <(tW−0.215 · t ² ). To claim 3
The laminated microwave induction element according to any one of the above. 6. The shortest distance between coiled lines adjacent to each other with an insulator layer interposed therebetween is defined as d _0, and at least at a position t / 2 inward in the width direction from the widthwise surface portion of the coiled line, The distance d adjacent to each other across the insulator layer is within a range of d ₀ <d ≦ (t−t ² / W + d ₀ ).
The laminated microwave induction element according to any one of the above.