JP2001250723A - High-q high-frequency coil and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-Q high-frequency coil which has a high-Q over a wide frequency range of 100 MHz to a few GHz and can be easily manufactured. SOLUTION: A first conductor layer 11, an interlayer insulating resin layer 12, and a second conductor layer 13 are formed on the one surface of an insulating board, a coil conductor is composed of the conductor layers 11 and 13, 15 μm or above in height, and has an aspect ratio from 0.5 to 3, and the aspect ratio of a space between the adjacent winding parts of the coil conductor is set at 1.5 or below. The interlayer insulating resin layer 12 interposed between the conductor layers is 20 μm to 100 μm in thickness and formed of organic material whose permittivity is 5 or below.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency coil for a signal, and more particularly to a high-Q high-frequency coil having a high Q value in a wide high-frequency band of 100 MHz to several GHz and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, examples of techniques for increasing the Q value of a high-frequency coil are as follows.

[0003] Thin-film coil conductors having a flat cross section are provided in multiple layers via an insulating layer, and are connected in parallel to increase the surface area and increase the Q (Japanese Patent Laid-Open No. 5-8234).
No. 9).

[0004] By increasing the thickness of the conductor to about 10 µm, the DC resistance is reduced, and Q is increased (Japanese Patent Laid-Open No. 6-84646).
No.).

[0005]

In the above structure, the number of layers increases and the process becomes complicated. Also, since thin film technology is used, the cross-sectional shape of the conductor is usually flat,
At high frequencies, current concentrates at the corners, and Q does not rise as expected. The surface current between the conductor layers is smaller on the inner side than on the outer side.
The comparison does not show that the latter is twice as large as the former.

In the above structure, the current is limited to the surface at high frequencies due to the skin effect. For example, even if the thickness is doubled with a conductor having a flat cross-section, the surface area hardly changes, so that Q Rise is small. Also 10μ
m cannot cover a wide frequency band of high frequencies.

[0007] In view of the above, the present invention provides a 100 MHz
An object of the present invention is to provide a high-Q high-frequency coil which exhibits a high Q value over a wide high-frequency band of up to several GHz and is easy to manufacture, and a method of manufacturing the same.

[0008] Other objects and novel features of the present invention will be clarified in embodiments described later.

[0009]

In order to achieve the above object, an invention according to claim 1 of the present application is a high-Q high-frequency coil having a coil conductor provided on at least one surface of an insulating substrate, wherein the coil conductor is provided. Is not less than 15 μm, the aspect ratio of the coil portion conductor is 0.5 or more and 3 or less, and the aspect ratio between adjacent conductor winding portions of the coil portion conductor is 1.5 or less. It is characterized by:

According to a second aspect of the present invention, in the first aspect, the coil portion conductor is at least two or more conductor layers, and an interlayer insulating layer interposed between the conductor layers has a relative dielectric constant of 5 or more.
The following organic materials whose thickness is 20 μm or more and 100 μm
It is characterized as follows.

A third aspect of the present invention is characterized in that, in the second aspect, the interlayer insulating layer is made of an epoxy resin or an acryl-modified epoxy resin.

A fourth aspect of the present invention is characterized in that, in the second aspect, the interlayer insulating layer is made of vinylbenzyl.

The invention of claim 5 of the present application is directed to claims 1, 2, 3
Or 4 is characterized in that the insulating substrate is an organic material base material having a relative permittivity of 5 or less or a material obtained by adding a core material thereto.

According to a sixth aspect of the present invention, in the fifth aspect, the base material is made of vinylbenzyl.

The invention of claim 7 of the present application is directed to claims 1, 2,
In 3, 4, 5, or 6, the coil portion conductor is constituted by a plurality of conductor layers, and at least one or more conductor layers are formed with one or more turns of a spiral or helical conductor portion, and the insulating substrate The area of the central portion of the substrate surface where there is no conductor is 20% or more of the entire layout area of the coil portion conductor.

[0016] The invention of claim 8 of the present application provides claims 2 and 3
4, 5, 6, or 7, wherein the connection between the conductor layers is formed by a blind via, and a junction area of the blind via is 0.03 mm ² or less.

The invention of claim 9 of the present application is directed to claims 1, 2,
In 3, 4, 5, 6, 7 or 8, the coil conductor is characterized in that two or more corners of the conductor cross section are rounded.

According to a tenth aspect of the present invention, there is provided a method of manufacturing a high-Q high-frequency coil, comprising: forming a base metal film having a thickness of 2 μm or less on an insulating substrate; and providing a resist film on the base metal film. And a resist film forming step of exposing the base metal film in a portion to be a coil portion conductor; an electroplating step of forming a metal plating film on the exposed portion of the base metal film by the electroplating; A resist stripping step of stripping, and an etching step of etching the entire surface of the insulating substrate until the underlying metal film between the metal plating films is removed.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a high-Q high-frequency coil and a method of manufacturing the same according to the present invention will be described below with reference to the drawings.

A first embodiment of a high-Q high-frequency coil and a method of manufacturing the same according to the present invention will be described with reference to FIGS.
FIG. 1 is a front sectional view of a high-Q high-frequency coil, FIG. 2 shows a conductor layer and an interlayer insulating resin layer, and FIG. 3 shows an example of a method of manufacturing a coil conductor.

In these figures, 1 is an organic insulating substrate,
11 is a first conductor layer, 12 is an interlayer insulating resin layer, and 13 is a second conductor layer.
The conductor layer 14 is a terminal electrode. The first conductor layer 11, the interlayer insulating resin layer 12, and the second conductor layer 13 are formed on the main surface (upper surface) of the substrate 1, and the terminal electrodes 14 are formed so as to cover side surfaces of the substrate 1 and part of upper and lower surfaces. ing.

Conventionally, inorganic ceramics such as alumina and glass have been used for the substrate. However, alumina has high mechanical strength but a high relative dielectric constant of about 9, which is not preferable as a substrate for high-frequency coil parts. In addition, glass has a low dielectric constant but is brittle, and when forming a thick conductor layer as in this example, the stress increases both when forming by a dry method such as sputtering and when forming by plating, so that the substrate is cracked or chipped. It is not preferable because it is easy. The organic insulating substrate 1 is preferable in the case of this example because it has a small dielectric constant and a certain degree of flexibility.

Here, the organic insulating substrate 1 is formed by impregnating a core material (reinforcing material) such as glass cloth or Kevlar cloth with a base resin such as vinyl benzyl and the like, and using a ratio of the whole substrate. The dielectric constant is set to 5 or less. When the relative dielectric constant exceeds 5, the stray capacitance between the substrate 1 and the electrode 14, between the coil conductors of the first and second conductor layers 11 and 13, and furthermore, in the coil conductor of the same layer increases, and the This is disadvantageous in increasing the resonance frequency of the coil, and the use of an organic insulating substrate is no longer necessary.

The base material of the organic insulating substrate 1 may be selected from, for example, the following Table 1 in consideration of the frequency used, the target Q value, and the cost.

Table 1 Product name Relative permittivity Q fluororesin 2.1 10,000 Polyethylene 2.2 5000 PPO 2.5 1200 Vinylbenzyl 2.5 260 Cyanate ester 2.7 1000 Polyetherimide 3670 Polyimide 3.6 200 Epoxy 4.370 Among the materials listed in Table 1, vinylbenzyl is a preferable material because it has a good balance of relative permittivity, Q, and cost.

When a core material is used for the organic insulating substrate 1, D glass cloth, E glass cloth, Kevlar cloth, or the like can be used as shown in Table 2 below. Generally, a material having a lower dielectric constant and a lower loss is more expensive, but it is preferable to use a material having a lower dielectric constant as far as the cost permits.

[0027]

Instead of a cloth, a film of a flexible and low dielectric constant organic material such as polyimide or polyethylene can be used as the core material of the substrate 1. In this case, the dielectric constant of the entire substrate can be significantly reduced, and the high-frequency characteristics of the coil can be improved. In this case, the adhesion between the base material such as vinylbenzyl and the organic material film as the core material may be insufficient.In this case, many small holes are formed in the film, or the surface of the film is coated with potassium permanganate. It can be improved by chemically roughening or physically roughening by polishing. It is also preferable to provide an adhesive layer made of a thin organic low dielectric constant material on both sides of the film. The core material can be formed further in the center, formed on the front and back of the base material, or a combination thereof depending on the required mechanical strength and reliability.

As shown in FIG. 2A, the first conductor layer 11 is composed of a coil conductor 11a having one or more turns of a spiral conductor and a lead electrode conductor 11b located at both edges of the organic insulating substrate 1. In other words, it is manufactured by a process combining pattern plating and quick etching. First, FIG.
After roughening the surface of the organic insulating substrate 1 as shown in FIG.
Underlying metal film 20 of 2 μm or less by electroless plating of copper or the like
Is formed (underlying metal film forming step). Next, FIG.
A resist film 21 is provided on the underlying metal film 20 as described above, and a portion of the underlying metal film that is to be a coil conductor is exposed (resist film forming step of forming a bank with a resist). Then, as shown in FIG. 3C, the base metal film 2 is formed by electroplating.
A metal plating film 22 of copper or the like is formed on the exposed portions of 0 (electroplating step). Thereafter, as shown in FIG. 3D, the resist film 21 is entirely stripped (resist stripping step). After the resist is stripped, the entire surface of the organic insulating substrate 1 is etched until the underlying metal film 20 between the metal plating films 22 is removed (quick etching step) as shown in FIG. 5-3) The coil conductor is obtained.

If the thickness of the underlying metal film exceeds 2 μm, it takes a long time to remove it in the quick etching step, and the metal plating film 22 is also thinned by etching, which is not preferable.

The thickness of the coil conductor 11a (the first conductor layer 1
1) is intended to be at least twice the skin depth value at the lower limit frequency of the operating frequency band. If the lower limit of the operating frequency is 100 MHz and the type of conductor is copper, the above thickness is 1
5 μm or more.

At frequencies near the upper limit of the operating frequency band, the current is limited near the surface of the conductor due to the skin effect.
Therefore, Q is substantially proportional to the perimeter of the cross section of the conductor. Therefore, since the conductor height is preferably as high as possible, the aspect ratio of the coil conductor 11a is set to 0.5 or more. However, if the height is too high, the stray capacitance between adjacent conductor winding portions in the coil portion conductor 11a increases, and manufacturing becomes difficult. Therefore, the aspect ratio is set to 3 or less. If the aspect ratio is less than 0.5, Q decreases, and if it exceeds 3, the resonance frequency decreases with an increase in stray capacitance. Coil conductor 1
The conductor spacing in 1a is preferably as large as possible to reduce stray capacitance. However, since the inductance value cannot be obtained if the distance is too large, the lower limit is set to 1.5 for the aspect ratio of the gap between conductors. That is, the pattern is such that the aspect ratio between adjacent conductor winding portions is 1.5 or less.

Although there is a problem that Q is reduced due to concentration of a corner portion of a current at a high frequency, according to the above quick etching, as shown in FIG.
Since a certain degree of rounding is applied to two or more corners of the conductor cross-sections a and 13a, it is possible to prevent a current at a high frequency from being biased toward the corners as compared with a case where the corners are sharp. It can contribute to the rise of the value.

On the first conductor layer 11 described above, the contact hole removal patterns 12a and 12a as shown in FIG.
An interlayer insulating resin layer 12 made of epoxy resin, modified epoxy resin, vinyl benzyl, or the like on which b is formed is formed. After the screen printing of the insulating resin, the interlayer insulating resin layer 12 can be formed into a required pattern by a photolithography process.

Thereafter, the second conductor layer 13 having the coil conductor 13a and the lead electrode conductors 13b located at both edges of the organic insulating substrate 1 is formed in the same process as the first conductor layer 11 as shown in FIG.
It is formed as shown in FIG. First and second conductor layers 11, 1
Reference numeral 3 denotes a cut pattern 12a, 12b of the interlayer insulating resin layer 12.
Interconnected through That is, the cut pattern 12
a, contact holes 15 formed in portions 12a and 12b
a, via hole 15b.

As the metal material used for the first and second conductor layers 11 and 13, besides copper, a material having a small specific resistance such as silver or gold can be used. However, in the case of manufacturing by a process combining the above pattern plating and quick etching, it is necessary that the material be capable of electroplating,
Further, it is necessary to consider the reactivity with the insulating material and the migration property.

The interlayer insulating resin layer 12 has a relative dielectric constant of 5 or less and a thickness of 20 μm or more and 100 μm or less, so that the resonance frequency of the high-frequency coil is made as high as possible. When the relative dielectric constant of the interlayer insulating resin layer 12 exceeds 5, the stray capacitance between the substrate 1 and the electrode 14, between the coil conductors of the first and second conductor layers, and furthermore, in the coil conductor of the same layer increases, and the This is disadvantageous for increasing the resonance frequency of the coil. Further, if the thickness of the interlayer insulating resin layer 12 is less than 20 μm, the stray capacitance also increases, which is not preferable. If the thickness exceeds 100 μm, warpage is a problem.

The thickness of the interlayer insulating resin layer 12 is preferably as large as possible in order to reduce the stray capacitance, particularly the stray capacitance between the coil conductors, and preferably has a low dielectric constant. Adhesiveness, workability,
It is necessary to consider the problem of warpage and even step coverage. As for the insulating resin material, polyimide is generally used in many cases. However, step coverage is poor, and there is a problem of warpage. Therefore, it is difficult to form the insulating resin material to be thick, and usually, the limit is 10 μm. When an epoxy resin is formed by a screen printing method or the like, good step coverage can be obtained.
Even in the case of μm, the surface becomes almost flat after drying. A material having a relative dielectric constant of about 3.5 can be used, which is preferable. The use of vinylbenzyl is suitable when the relative dielectric constant is as small as 2.5 and the resonance frequency needs to be increased to the maximum.

The area of the via hole 15b in the coil conductors 11a and 13a of the first and second conductor layers 11 and 13 is set to 0.03 mm ² or less. Thus, it is possible to prevent a conductor having a large area from being present at a location where the magnetic flux of the high-frequency coil is concentrated, thereby causing a high-frequency loss and reducing Q, and at the same time, sufficiently increasing the number of turns of the spiral pattern. In forming the via hole, it is indispensable to form a blind via having a small floor area by using a build-up method or the like in order to reduce the size and performance of the coil.

Further, on the substrate surface of the organic insulating substrate 1, a portion without a conductor is provided at the center portion over a plurality of layers, and the area of the portion without the conductor is equal to the layout area of the entire coil portion conductor (not including the extraction electrode conductor). It is set to be 20% or more. This is to prevent a decrease in Q due to the presence of the conductor at the center of the substrate.

As shown in FIG. 1, the terminal electrode 14 is
Are formed so as to cover the side surfaces and the upper and lower surfaces. However, usable metal materials include copper, silver, and gold, and plating may be performed in consideration of solderability. Terminal electrode 14
Can be formed by a vacuum film forming method such as vapor deposition and sputtering, as well as a method of bonding a metal foil, in addition to a plating method. In the example of FIG. 1, the terminal electrode 14 is also formed on the side of the substrate in consideration of the fixing strength to the substrate 1. In this case, the stray capacitance with the conductor pattern via the substrate 1 increases,
It is particularly important to employ a substrate with a low dielectric constant. The relative dielectric constant of the substrate 1 is preferably 5 or less, and particularly preferably 4 or less. Also, in this case, thermal stress when soldering the coil to the printed wiring board increases, so that it is effective to use an organic material that is resistant to cracking.

According to the first embodiment, the following effects can be obtained.

(1) In order to widen the usable frequency band, the thickness of the coil-portion conductors 11a and 13a should be at least twice as large as the skin depth at 100 MHz when copper is used (1).
5 μm or more) and can be used in a wide high-frequency band of 100 MHz to several GHz.

(2) In order to increase the surface area of the coil portion conductors 11a and 13a, the cross-sectional shape of the conductor is made as long as possible, that is, the aspect ratio of the conductor cross section is 0.5 or more, and Q The value can be kept high. Also,
In accordance with the above, the stray capacitance between conductors increases, so that the distance between lines is widened, and the conductor spacing is about 0.7 times or more the conductor height, in other words, the aspect ratio between adjacent conductor winding portions is 1 unit. .5 or less. Thereby, a decrease in the resonance frequency can be avoided.

(3) Organic insulating substrate 1 having a relative dielectric constant of 5 or less
Is used to reduce the stray capacitance between the terminal electrode and the coil conductor and in the coil conductor of the same layer, and to use the interlayer insulating resin layer 12 having a relative dielectric constant of 5 or less and a film thickness of 20 to 100 μm. The stray capacitance between the coil conductors in the same layer and in the same layer can be reduced. As a result, the resonance frequency can be improved.

(4) To increase the inductance value without lowering the Q value by setting the area of the central portion where there is no conductor over the multilayer of the conductor layer on the substrate surface to be 20% or more of the arrangement area of the entire coil portion conductor. Can be.

(5) By connecting the plurality of conductor layers 11 and 13 with via holes having a joint area of 0.03 mm ² or less, it is possible to avoid an increase in loss at high frequencies and a decrease in Q. It is. On the other hand, if a through hole is used for connection between the conductor layers, a short ring is formed at the center of the coil where the magnetic flux is concentrated, and the Q value of the coil at a high frequency is greatly reduced. If the floor area is large, the number of windings cannot be increased particularly when a spiral pattern is formed. By forming a blind via with a small floor area using a build-up method or the like, it is possible to reduce the size and improve the performance of the coil.

(6) When the conductor is thickened, stress at the time of formation becomes a problem. However, avoid a material such as glass which has a low dielectric constant but is easily broken, and use a substrate made of a low dielectric constant organic material such as vinylbenzyl. By using it, cracking and chipping can be prevented, and reliability can be improved.

(7) When the conductor is thickened, the interlayer insulating resin film 1
The step coverage at the time of forming 2 becomes a problem, but this problem can be solved by using an epoxy resin or vinyl benzyl having good step coverage.

(8) When the coil conductors 11a and 13a are manufactured by the quick etching step, the two corners of the conductor end face are rounded (R is added), so that it is possible to avoid the corner concentration of the current at a high frequency. In this respect, the Q can be improved.

(9) Efficiency of production can be achieved by using a method combining conductor plating and quick etching as a method of producing a conductor. Conventionally, this combination is not suitable when the conductor layer is thin because the conductor portion is also etched. If the conductor spacing is smaller than the conductor thickness, the fluidity of the etchant to the underlying conductor layer deteriorates, the etching rate of the underlying conductor layer decreases, and the etching time is prolonged. The amount was undesirably increased. In the case of this example, since the conductor layer is thick and the conductor interval is large, this combination is convenient and the process can be greatly reduced.

FIG. 4 shows the configuration of the conductor layer and the interlayer insulating resin layer according to the second embodiment of the present invention. In this case, the configuration up to the organic insulating substrate 1, the first conductor layer 11 in FIG. 4A and the interlayer insulating resin layer 12 in FIG. 4B is the same as that of the above-described first embodiment. The difference is that the second conductor layer 16 also forms a spiral pattern as shown in FIG. That is, the second conductor layer 16 is a coil conductor 16a having one or more turns of a spiral conductor.
And the extraction electrode conductors 16 located at both edges of the organic insulating substrate 1
b. Other configurations are the same as those of the first embodiment.
This embodiment is the same as the above embodiment, and the same or corresponding parts are denoted by the same reference numerals and description thereof will be omitted.

According to the second embodiment, since the first and second conductor layers 11 and 16 each have a coil-shaped conductor having a spiral pattern, the inductance can be increased. Other functions and effects are the same as those of the first embodiment.

FIG. 5 shows the configuration of the conductor layer and the interlayer insulating resin layer according to the third embodiment of the present invention. The first conductor layer 31 of FIG. 5A, the second conductor layer 33 of FIG. 5C, and the third conductor layer 35 of FIG.
a and the extraction electrode conductor 31b, the coil portion conductor 33a and the extraction electrode conductor 33b, the coil portion conductor 35a and the extraction electrode conductor 35b, and the coil portion conductors 31a, 33a and 35a.
Are connected to each other to form a winding conductor having a helical pattern as a whole.
In addition, the second interlayer insulating resin layer 34 is formed with punched patterns 32a, 32b, 34a, 34b for contact holes. The first and second conductor layers 31 and 33 are connected to each other through the cutout patterns 32 a and 32 b of the interlayer insulating resin layer 32. That is, the connection is made by the contact holes 36a and the via holes 36b formed in the portions of the cutout patterns 32a and 32b. Similarly, the second and third conductor layers 3
Reference numerals 3 and 35 denote removal patterns 34a of the interlayer insulating resin layer 34,
They are interconnected through 34b. That is, the connection is made by the contact holes 37a and the via holes 37b formed in the portions of the cutout patterns 34a and 34b.

The other structure can be the same as that of the first embodiment.

According to the third embodiment, the coil conductors 31a, 33a,
35a can form a winding conductor of a helical winding (helical pattern), and Q can be made larger than that of a spiral winding (spiral pattern). In the case of the helical winding, the condition that the area of the central portion of the substrate surface of the organic insulating substrate 1 where there is no conductor is 20% or more of the arrangement area of the entire coil portion conductor can be necessarily satisfied.

[0057]

The present invention will be described below in detail with reference to examples.

Example 1 E glass cloth having a relative permittivity of 7.2 was used as a core material (reinforcing material), and vinylbenzyl having a relative permittivity of 2.5 was impregnated with a base material. A 0.4 mm organic insulating substrate was prepared. At this time, the relative dielectric constant of the entire substrate was 3.2.

After the substrate surface was roughened, a copper layer having a thickness of 0.5 μm was formed as a base metal film 20 in FIG. 3A using an electroless copper plating solution. A positive resist film having a thickness of 50 μm was formed thereon by spin coating, and the pattern of FIG. 2A was exposed. The photomask used here has a transparent hatched portion in the figure. In this pattern, the spiral portion has a line width of 30 μm and a line interval of 40 μm.
m. Next, development was performed with a predetermined developing solution to form a resist film 21 exposing the underlying metal film 20 at the portion where the coil conductor of FIG. 3B was formed. Subsequently, 40 μm of bright copper sulfate plating was performed. After the resist film is stripped with a stripping solution as shown in FIG.
By etching, the first conductor layer 11 having the coil section conductor 11a and the lead electrode conductor 11b having the conductor cross section of FIG. 3E was formed in a spiral pattern as shown in FIG. 2A. The aspect ratio of the coil portion conductor 11a is about 1.3, and the aspect ratio between the adjacent conductor winding portions is about 1.

Next, an organic insulating material is formed by screen printing so that the thickness on the conductor is 30 μm after drying.
Thereafter, a pattern as shown in FIG. 2B was formed through a photolithography process. Here, the relative permittivity of the insulating material is 4.3. The via hole 15b for connecting the coil portion conductor is substantially a square having a side length of 70 μm. Thereafter, through the same steps as the first conductor layer 11, FIG.
The second conductor layer 13 as shown in (C) was formed. Thereafter, as shown in FIG. 1, terminal electrodes 14 were formed on the side surface and the back surface of the substrate to obtain a high-frequency coil. At this time, the inductance value was about 10 nH, and the Q value at 1 GHz was 80.

Comparative Example 1 A coil similar to that of Example 1 except that the thickness of the conductor was 10 μm was prepared. The Q value of this coil at 1 GHz is 50
Met. Since the aspect ratio of the coil portion conductor is low, it is considered that the Q is reduced due to the skin effect.

Embodiment 2 In Embodiment 1, only the pattern of the second conductor layer is shown in FIG.
(C) was changed and the coil was created. Conditions such as the aspect ratio of the coil conductor 16a of the second conductor layer 16 were the same as those of the coil conductor 11a of the first conductor layer 11. The inductance value at this time is about 20 nH, and 1 G
The Q value was 80 at Hz. It is understood that the inductance value can be increased by forming the first conductor layer 11 and the second conductor layer 16 in a spiral pattern.

Comparative Example 2 In the same process as in Example 2, coil-shaped conductors 40 and 41 having a spiral pattern shown in FIGS. 6A and 6B were formed on both surfaces of the substrate 1 to form a coil. The coil conductors on both sides are connected by a through hole 42 having a diameter of 0.2 mm. The cross-sectional shape of the coil conductor was the same as that of the second embodiment. In this case, the inductance value of the coil was almost the same as in Example 2. However, the Q at 1 GH dropped to 60. This is presumably because a large short ring was formed at the center of the coil due to the through hole, and the eddy current loss increased.

When a through hole (having a hollow portion) is used for connection between the conductor layers as in Comparative Example 2, a short ring is formed at the center of the coil where the magnetic flux concentrates, and the high frequency of the coil is reduced. Significantly lowers the Q value. In addition, the floor area increases, and the number of turns cannot be increased particularly when a spiral pattern is formed. Also, conductor loss at the land becomes a problem in the high frequency region. Therefore, it is understood that forming a blind via having a small floor area by using a build-up method or the like is indispensable for miniaturization and high performance of the coil.

Example 3 A helically wound coil as shown in FIG. 5 was prepared. The production method used was the method of Example 1 repeatedly. The cross-sectional shape of the conductor, the type of interlayer insulating resin, and the film thickness are the same as those in the first embodiment. The inductance value of this coil is 10 nH,
The Q value at 1 GHz was 100. It is considered that the increase in Q at 1 GHz is due to a decrease in eddy current loss between the wires of the coil part conductor.

In each of the conductor layers on which the coil conductors are formed, it is preferable to increase the area of the conductor-free portion provided at the center of the substrate as much as possible in order to increase Q. In this regard, the helical winding coil is most desirable. In the case of forming a large inductance value also in the spiral winding, it is preferable to form the spiral coil conductor by dividing the conductor into a plurality of conductor layers because the area of the central portion can be widened.

Also, the area of the joint should be as small as possible to increase Q. Conventionally, through holes are often used for bonding between layers when using an organic substrate,
Since a short ring is formed at a position of a strong magnetic field, the loss increases, and accordingly, the Q value decreases. This is not preferable, and the area of the junction tends to increase. It is preferable to form blind vias by a so-called build-up method.

Although the embodiments and examples of the present invention have been described above, it is to be understood by those skilled in the art that the present invention is not limited to these and various modifications and changes can be made within the scope of the claims. Would be self-evident.

[0069]

As described above, according to the present invention,
A high-Q high-frequency coil exhibiting a high Q value over a wide high-frequency band of 100 MHz to several GHz and which is easy to manufacture can be realized.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a high-Q high-frequency coil according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a conductor layer and an interlayer insulating resin layer according to the first embodiment.

FIG. 3 is an explanatory diagram showing a manufacturing process of each conductor layer in the first embodiment.

FIG. 4 is a plan view showing a conductor layer and an interlayer insulating resin layer according to a second embodiment of the present invention.

FIG. 5 is a plan view showing a conductor layer and an interlayer insulating resin layer according to a third embodiment of the present invention.

FIG. 6 is a plan view of both surfaces of a substrate for explaining a comparative example 2;

[Explanation of symbols]

Reference Signs List 1 organic insulating substrate 11, 13, 16, 31, 33, 35 conductor layer 11a, 13a, 16a, 31a, 33a, 35a coil portion conductor 11b, 13b, 16b, 31b, 33b, 35b conductor layer 12, 32, 34 interlayer Insulating resin layer 14 Terminal electrode 15a, 36a, 37a Contact hole 15b, 36b, 37b Via hole

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01F 41/04 H01F 41/04 C

Claims (10)

[Claims] 1. A high-Q high-frequency coil in which a coil conductor is provided on at least one surface of an insulating substrate, wherein the height of the coil conductor is 15 μm or more, and the aspect ratio of the coil conductor is 0.5. The high-Q high-frequency coil according to claim 3, wherein the aspect ratio between adjacent conductor winding portions in the coil portion conductor is 1.5 or less. 2. The coil part conductor is at least two or more conductor layers, and an interlayer insulating layer interposed between the conductor layers is an organic material having a relative dielectric constant of 5 or less and a thickness of 20 μm or more,
2. The high-Q high-frequency coil according to claim 1, which has a thickness of 100 μm or less. 3. The high Q according to claim 2, wherein said interlayer insulating layer is made of an epoxy resin or an acrylic-modified epoxy resin.
High frequency coil. 4. The high-Q high-frequency coil according to claim 2, wherein said interlayer insulating layer is made of vinylbenzyl. 5. The high-Q high-frequency coil according to claim 1, wherein said insulating substrate is made of an organic material base material having a relative permittivity of 5 or less or a core material added thereto. 6. The high-Q high-frequency coil according to claim 5, wherein said base material is made of vinylbenzyl. 7. The coil part conductor is composed of a plurality of conductor layers, at least one or more conductor layers are formed with one or more turns of a spiral or helical conductor part, and on a substrate surface of the insulating substrate. The high-Q high frequency coil according to claim 1, 2, 3, 4, 5, or 6, wherein the area of the central portion where there is no conductor is 20% or more of the arrangement area of the entire coil portion conductor. 8. The connection between the conductor layers is formed by a blind via, and the area of the junction of the blind via is 0.0.
8. The high-Q high-frequency coil according to claim ^2, which is 3 mm2 or less. 9. The coil conductor according to claim 1, wherein two or more corners of the conductor cross section are rounded.
The high-Q high-frequency coil according to 3, 4, 5, 6, 7, or 8. 10. A base metal film forming step of forming a base metal layer having a thickness of 2 μm or less on an insulating substrate, providing a resist film on the base metal film, and exposing the base metal film in a portion to be a coil conductor. Forming a metal plating film on an exposed portion of the base metal film by electroplating, a resist stripping step of stripping the resist film entirely, and removing the entire surface of the insulating substrate with the metal. An etching step of etching until the underlying metal film between the plating films is removed.