JP2002280219A - Inductor and/or circuit wiring near in vicinity and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an inductor and/or a circuit wiring near thereat, capable of obtaining characteristics satisfying at a frequency of GHz or higher, while being a circuit board adhering a general purpose copper plate, and to provide a method for manufacturing the same. SOLUTION: The inductor 10 comprises a satisfactory conductive metal thin film layer, such as a copper-plating layer 5, a nickel-plating layer 6 and a gold-plating layer 7 laminated in a structure in the thickness direction on an upper surface of a spiral copper plate inductor pattern 2 formed on the same surface, by working the copper plate 4 part of a substrate 1 covered with the plate 4 having a thickness of 10 μm or smaller on the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inductor used for a microwave integrated circuit, a circuit wiring near the inductor, and a method of manufacturing the same.

[0002]

2. Description of the Related Art First, a conventional method of manufacturing an inductor and a structure of an inductor manufactured by the manufacturing method will be described with reference to FIGS.

FIG. 5 is a plan view of a circuit board on which a microwave integrated circuit incorporating a prior art inductor is mounted, and FIG. 6 is a prior art inductor indicated by an arrow A on the circuit board shown in FIG. A is a plan view, FIG. B is a cross-sectional side view of the inductor pattern taken along line AA of FIG. A, and FIG. C is another shape of the inductor pattern shown in FIG. 7 is a cross-sectional side view of a general substrate having a surface coated with a copper plate, and FIG. 7B is a continuation of FIG. FIG. C is a cross-sectional side view of a copper plate etching step following FIG. B, and FIG. D is a cross-sectional side view of a resist film removing step following FIG. C.

[0004] In recent years, with the spread of wireless communication devices such as cellular phones and the like, there is an increasing demand for downsizing, weight reduction, and cost reduction of such devices. Further, as the amount of information increases, higher frequencies are desired.

In order to obtain more excellent characteristics in a high frequency range, an inductor used at a frequency of GHz or higher requires a technique for improving the material of a dielectric substrate and miniaturizing a conductor pattern.

[0006] With respect to the technique for miniaturizing the conductor pattern, the conductor pattern can be miniaturized by using a thin film technique. By miniaturizing the conductor pattern, the length of the inductor can be increased, a desired inductance can be obtained, and high-frequency resistance can be reduced by increasing the thickness of the conductor pattern. However, the above-described technique increases the cost and is difficult to use in a general printed circuit board manufacturing process.

That is, in the above-described general printed circuit board manufacturing process, a substrate to which a copper foil plate (hereinafter, referred to as “copper plate”) is adhered is used. An inductor formed on such a substrate is shown in FIGS.

In FIGS. 5 and 6, reference numeral 1 denotes a substrate made of a resin such as a polyimide film or a liquid crystal polymer, reference numeral 2 denotes an inductor pattern, reference numeral 3 denotes a gold (Au) wire, and reference numeral 4 denotes a copper (Cu) plate. .

Such an inductor pattern 2 is shown in FIG.
It is obtained through a manufacturing process as shown in FIG.

First, as shown in FIG. 7A, a substrate 1 to which a copper foil plate 4 is adhered is prepared. The thickness of the copper plate 4 is 15 μm to 20 μm. Next, as shown in FIG. 2B, the inductor pattern 2 is formed on the copper plate 4 with a resist (photosensitive resin) 20. Then, as shown in FIG. C, the copper plate 4 is etched to form a pattern similar to the inductor pattern 2. Thereafter, the resist 20 is peeled off as shown in FIG.

Generally, the inductor pattern 2 is formed by such a process.

[0012]

Generally, in order to accurately form an inductor pattern 2 from a copper plate 4 and obtain a desired inductance, the inductor pattern is formed using a thin copper plate of, for example, about 1 μm to 3 μm. However, doing so will increase the conductor resistance.

Therefore, if the copper plate 4 is made thicker, for example, to about 20 μm to form an inductor, the conductor resistance can be reduced.
6B or FIG. 6C, a pattern in which the shape of the inductor pattern 3 and the adjacent interval are broken is formed, and a desired inductance value can be obtained in a stable state. difficult. Such collapse of the shape of the conductor is particularly remarkable when a fine pattern having a line width of 30 μm and a line interval of 30 μm is formed, and it is possible to form an inductor having a satisfactory characteristic at a frequency of GHz or more. could not.

The problem to be solved by the present invention is as follows.
Although it is a circuit board to which a general copper plate is bonded, GH
It is an object of the present invention to obtain an inductor that can obtain satisfactory characteristics at a frequency of z or more, or a circuit wiring near the inductor, and a method for manufacturing the same.

[0015]

According to the present invention, in order to solve this problem, according to the present invention, an inductor and / or a circuit wiring near the inductor are replaced with a copper plate portion of an insulating substrate having a surface with a copper plate having a thickness of 10 μm or less. It has a structure in which a good conductive metal thin film layer is laminated in the thickness direction on the upper surface of a spiral copper plate inductor pattern formed on the same surface and / or a copper plate circuit wiring pattern in the vicinity thereof. It is characterized by the following.

It is preferable that the good conductive metal thin film layer is composed of a thin film layer of copper, nickel or gold from the copper plate side, and these may be plated layers. It is preferable that the copper plate circuit wiring in the vicinity thereof and the whole of the good conductive metal thin film layer formed on the upper surface thereof are covered with a gold thin film, and the gold thin film has a thickness of 0.1 μm to 3 μm. It is preferred that

Further, a manufacturing method of processing a copper plate portion of an insulating substrate having a surface on which a copper plate having a thickness of 10 μm or less is adhered to form a spiral inductor and / or circuit wiring near the same on the same surface. An etching step of etching the copper plate to form the copper plate inductor pattern and / or a copper plate circuit wiring pattern in the vicinity thereof, and covering a portion other than the copper plate inductor pattern and / or the vicinity of the copper plate circuit wiring pattern portion with a resist. A resist coating step, and a metal thin film deposition step of depositing a good conductive metal thin film in the thickness direction on an upper surface of the copper plate inductor pattern not covered with the resist and / or a copper plate circuit wiring pattern portion in the vicinity thereof. A resist film removing step of removing the resist film after completion of the metal thin film applying step. You have me.

The good conductive metal thin film is formed in the order of copper, nickel and gold thin film layers from the copper plate side. Further, after the resist film peeling step is completed, a gold coating step of coating the copper plate inductor pattern and / or a copper plate circuit wiring pattern in the vicinity thereof and the surface of the good conductive metal thin film formed on the upper surface thereof with a gold thin film. It is desirable to add. Its thickness is desirably 0.1 μm to 3 μm. Further, it is desirable that these good conductive metal thin films or copper, nickel and gold thin film layers are formed by plating. Preferably, the insulating substrate is formed of polyimide or liquid crystal polymer.

Therefore, according to the inductor of the present invention and the circuit wiring in the vicinity thereof, the inductor and the circuit wiring in the vicinity thereof are formed in a laminated structure of an extremely thin copper plate having a thickness of 10 μm or less and a good conductive metal thin film layer. In particular, since at least the outermost layer of the good conductive metal thin film layer is formed of a gold thin film layer, the high-frequency resistance can be greatly reduced, and it can be used for high-frequency signals of GHz.

In addition, an insulating substrate coated with an extremely thin copper plate having a thickness of 10 μm or less is used, and the thin copper plate is etched to form a copper plate inductor pattern having a high-precision line width and interval and a copper plate circuit in the vicinity thereof. A wiring pattern can be created, and then other circuit patterns are covered with a resist so that only the copper plate inductor pattern and / or the copper plate circuit wiring pattern in the vicinity thereof are exposed, and exposed along the resist pattern. Generally, such as a polyimide substrate by increasing the thickness by laminating a good conductive metal thin film, particularly a gold thin film layer in the thickness direction on the upper surface of the copper plate inductor pattern and / or the copper circuit wiring pattern in the vicinity thereof. Inductor with low high-frequency resistance and low variation in inductance value despite being a circuit wiring board It is possible to obtain.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing an inductor and a circuit wiring near the inductor according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of an inductor according to an embodiment of the present invention and circuit wiring in the vicinity thereof, FIG. 2 is an enlarged sectional view of a part of the inductor and circuit wiring in the vicinity thereof shown in FIG.
FIG. 3 is a diagram showing the first half of a method of manufacturing an inductor and a circuit wiring near the inductor according to an embodiment of the present invention, and FIG.
FIG. 4 is a view showing a latter half of the step following the step shown in FIG. 3.

First, the structure of an inductor according to an embodiment of the present invention and circuit wiring near the inductor will be described with reference to FIGS. In the following description, the structure of the inductor will be mainly described. The circuit wiring in the vicinity of the inductor only has a different shape, and the structure is the same as that of the inductor itself.

In FIG. 1, reference numeral 10 indicates an inductor according to one embodiment of the present invention, and reference numeral 9 indicates a circuit wiring formed near the inductor 10 according to one embodiment of the present invention. Both the inductor 10 and the circuit wiring 9 are formed in the same plane of the substrate 1 made of a resin such as a polyimide film or a liquid crystal polymer. Also, the windings of the inductor 10 are all spirally formed on the same plane. One end of the center of the spiral of the inductor 10 is connected to the circuit wiring 9 near the center.
A is wire-bonded to A with the other end, and the other end is directly connected to the circuit wiring 9B.
It is connected to an external high-frequency circuit.

As shown in FIG. 2, the inductor 10 of the present invention is based on a substrate 1 on which a copper plate 4 having a thickness of 10 μm or less is adhered. It is formed by. The structure is such that a good conductive metal thin film layer, for example, on the upper surface of the copper plate inductor pattern 2 obtained by processing the copper plate 4 in a spiral shape in the thickness direction, for example,
It has a structure in which a copper thin film layer 5, a nickel thin film layer 6, and a gold thin film layer 7 are stacked from the copper plate inductor pattern 2 side.

Each of the above thin film layers is preferably a plating layer. Further, as shown in FIG. 2B, the entire lamination of these thin film layers may be covered with a gold thin film 8 having a thickness of 0.1 μm to 3 μm.

The size of the inductor 10 is such that the line width of the vortex is, for example, about 30 μm, and the interval width is also about 30 μm, and two inductors 10 can be formed within a 1 mm square range. It is of size.

By configuring the inductor 10 with the above structure, it is possible to reduce the electrical resistance to high-frequency signals of GHz or higher while using a general substrate coated with a copper plate 4. Further, since the circuit wirings 9A and 9B through which the high-frequency signal of GHz or more passes are also formed on the same substrate with the same structure, it is possible to transmit without loss.

Next, a method of manufacturing the inductor 10 will be described with reference to FIGS.

First, as shown in FIG. 3A, a copper foil plate 4
A substrate 1 to which is adhered is prepared. As described above, the substrate 1 is, for example, a substrate made of a resin such as a polyimide film or a liquid crystal polymer, and the thickness of the copper plate 4 is 10 μm or less, and is a surface to be etched first. Next, FIG.
In the process shown in (1), a resist (photosensitive resin) is formed on the copper plate 4.
At 20, an inductor pattern is formed. As shown in FIG. 1, the shape of the inductor pattern is spirally formed on the same plane.

Then, in the step shown in FIG. 4C, the copper plate 4 in the portion not covered with the resist 20 is etched, and then the resist 20 is removed to form the spiral copper inductor pattern 2.

Subsequently, in the step shown in FIG. D, other than the copper inductor pattern 2, that is, the inductor pattern 2
Is covered with a resist 21.

Then, in the step shown in FIG. 4A, for example, copper is plated on the surface of the copper inductor pattern 2 to form a copper plating layer 5. The thickness of the copper plating layer 5 is about 10 μm to 50 μm.

Next, in the step shown in FIG. 6B, for example, nickel (Ni) is plated on the surface of the copper plating layer 5 to form a nickel plating layer 6. The thickness of the nickel plating layer 6 is about 1 μm to 10 μm.

Subsequently, in the step shown in FIG. 4C, for example, gold (Au) is plated on the surface of the nickel plating layer 6 to form a first gold plating layer 7. The thickness of the gold plating layer 7 is about 0.1 μm to 10 μm.

Thereafter, the resist 21 is peeled off in the step shown in FIG. FIG. 2A shows a cross section of the inductor pattern 2 in this case. A copper plate 4, a nickel plating layer 6, a copper plating layer 5
Is directly exposed, so that gold plating is performed so as to cover the side walls thereof, including the surface of the first gold plating layer 7,
A second gold plating layer 8 is formed. FIG. 2B shows an enlarged cross section of the inductor pattern 2 having a structure covered with the second gold plating layer 8. The thickness of the second gold plating layer 8 is 0.1
It is about 3 μm to 3 μm.

In this way, as shown in FIG. 1, the inductor 10 of the present invention and the circuit wirings 9A and 9B near the inductor 10 can be formed on the substrate 1. This inductor 10 does not have the shape collapse of the conducting wire as seen in the inductor pattern 2 of the prior art, and has a constant inductance value.

The sectional structure of the inductor 10 may be essentially a single-layer structure of a thin film of a good conductive metal such as gold. However, since gold is expensive, it is desirable to stack thin copper, nickel and gold thin film layers as described above. The nickel plating (thin film) layer 6 in this case is a barrier layer for preventing copper from diffusing from the copper plating layer 5 below to the gold plating layer 7 above.

[0039]

As described above, according to the present invention, an inductor having a low high-frequency resistance and a small inductance value variation and a circuit wiring in the vicinity thereof are generally used copper plate-coated substrates, but have a small inductance value. Can be obtained. Numerous excellent effects can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view of an inductor according to an embodiment of the present invention and circuit wiring in the vicinity thereof.

FIG. 2 is an enlarged cross-sectional view of a part of the inductor shown in FIG. 1 and a circuit wiring near the inductor.

FIG. 3 is a cross-sectional side view showing the first half of a method of manufacturing an inductor and a circuit wiring near the inductor according to one embodiment of the present invention.

FIG. 4 is a cross-sectional side view showing a latter half of the step following the step shown in FIG. 3;

FIG. 5 is a plan view of a circuit board on which a microwave integrated circuit incorporating a conventional inductor is mounted.

6 shows a conventional inductor pattern indicated by an arrow A on the circuit board shown in FIG. 5, wherein FIG. 6A is a plan view thereof, and FIG. 6B is an inductor pattern on line AA of FIG. C is a cross-sectional side view of another shape of the inductor pattern shown in FIG.

7A and 7B are manufacturing process diagrams of a prior art inductor, in which FIG. A is a cross-sectional side view of a general substrate having a surface covered with a copper plate, and FIG. B is a resist coating process subsequent to FIG. FIG. C is a cross-sectional side view of the copper plate etching step following FIG. B, and FIG. D is a cross-sectional side view of the resist film removing step following FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Copper plate inductor pattern, 3 ... Gold wire, 4 ... Copper plate, 5 ... Copper plating layer, 6 ... Nickel plating layer, 7 ... 1st gold plating layer, 8 ... 2nd gold plating layer, 9A,
9B: circuit wiring of one embodiment of the present invention, 10: inductor of one embodiment of the present invention, 20: resist

Claims (11)

[Claims] 1. A spiral copper plate inductor pattern formed on a same surface by processing a copper plate portion of an insulating substrate having a surface on which a copper plate having a thickness of 10 μm or less is adhered and a copper plate circuit wiring in the vicinity thereof. An inductor and / or a circuit wiring near the inductor, wherein a good conductive metal thin film layer is laminated on a top surface of the pattern in a thickness direction thereof. 2. The method according to claim 1, wherein the good conductive metal thin film layer is formed of a copper, nickel, or gold thin film layer from the copper plate inductor pattern and / or a copper plate circuit wiring pattern in the vicinity thereof. And the circuit wiring in the vicinity thereof. 3. The inductor according to claim 1, wherein the good conductive metal thin film layer or each of the thin film layers is a plating layer. 4. The copper sheet inductor and / or copper sheet circuit wiring in the vicinity thereof and the whole of the good conductive metal thin film layer formed on the upper surface thereof are covered with a gold thin film. 4. An inductor according to claim 3, and / or a circuit wiring in the vicinity thereof. 5. The gold thin film layer has a thickness of 0.1 μm to 3 μm.
The inductor according to claim 4, and / or a circuit wiring near the inductor. 6. An inductor for forming a spiral inductor and / or a circuit wiring in the vicinity thereof by processing a copper plate portion of an insulating substrate having a copper plate having a thickness of 10 μm or less adhered to a surface thereof, and / or In the method of manufacturing circuit wiring in the vicinity thereof, an etching step of etching the copper plate to form the copper plate inductor pattern and / or a copper plate circuit wiring pattern in the vicinity thereof; and the copper plate inductor pattern and / or a copper plate circuit wiring pattern portion in the vicinity thereof A resist coating step of coating a portion other than the resist with a resist; and covering the upper surface of the copper plate inductor pattern not coated with the resist and / or a copper plate circuit wiring pattern portion in the vicinity thereof with a good conductive metal thin film in the thickness direction. A metal thin film deposition step of depositing the resist film after the metal thin film deposition step is completed. A method for producing an inductor and / or a circuit wiring in the vicinity thereof, the method including a dist coat film removing step. 7. A method for manufacturing an inductor and / or a circuit wiring in the vicinity thereof, wherein the good conductive metal thin film is formed in the order of a thin film layer of copper, nickel, and gold from the copper plate side. 8. After the resist film peeling step is completed,
7. A gold coating step of coating a surface of the copper plate inductor pattern and / or a copper plate circuit wiring pattern in the vicinity thereof and the surface of the good conductive metal thin film formed on the upper surface thereof with a gold thin film. A method of manufacturing the inductor according to claim 7 and / or a circuit wiring in the vicinity thereof. 9. The gold thin film has a thickness of 0.1 μm to 3 μm.
9. The method for manufacturing an inductor and / or a circuit wiring near the inductor according to claim 8, wherein: 10. The inductor according to claim 6, wherein the good conductive metal thin film or the thin film layer of copper, nickel or gold is formed by plating. Wiring manufacturing method. 11. A method for manufacturing an inductor and / or circuit wiring near the inductor, wherein the insulating substrate is formed of polyimide or liquid crystal polymer.