JPH0430406A - High frequency coil - Google Patents

Abstract

PURPOSE:To make the amount of decrease of conductor resistance larger than the amount of decrease of inductance, and to improve Q by the relative increase of L by forming coil conductors in a manner to be opposed to each other with an insulated substrate interposed and equalizing the current direction of each coil. CONSTITUTION:According to a chip type high frequency coil 1, first and second coil conductors 3 and 4 are formed opposing with each other pinching a substrate 2 on both main surfaces 2a and 2b of the insulated substrate 2, the outer edges 3a and 4a of the conductors 3 and 4 are connected to an input electrode 5, and each of inner edges 3b and 4b is connected to an output electrode 6. When the same amounts of current are allowed to flow in the coil conductors 3 and 4, conductor resistance can be reduced almost to half, also the decrease of inductance can be controlled, and the Q of the coil can be improved to the extent of the above-mentioned reduction. According to this constitution, it is unnecessary to increase the film thickness and the wire width of the coil conductor, an increase in size of component parts can be prevented, and the occurrence of the problems such as an under-etching and the like can also be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a high-frequency coil formed by forming a band-shaped coil conductor on the surface of an insulating substrate, and in particular relates to a high-frequency coil that is formed by forming a band-shaped coil conductor on the surface of an insulating substrate. , relates to a structure that can improve the Q of a coil.

[Conventional technology]

High-frequency coils used in high-frequency microwave circuits, for example, have a spiral-type coil conductor formed on the surface of an insulating substrate, and output electrodes are formed on the left and right edges of the substrate. The outer end and inner end of the coil conductor are connected to electrodes. In such a high-frequency coil, since the coil conductor is formed by a thin film technique such as sputtering or vapor deposition, there is a problem that the conductor resistance is increased due to the thin film thickness of the coil conductor, and the Q is correspondingly low. Therefore, in order to increase the Q of the coil, conventionally, the film thickness of the coil conductor is increased or the line width of the coil conductor is increased to decrease the conductor resistance.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional high-frequency coil, there is a problem in that increasing the line width of the coil conductor increases the size of the board, making it impossible to respond to recent miniaturization. In addition, simply increasing the thickness of the coil conductor increases the etching time, resulting in under-etching.As a result, there is a limit to how thick the coil conductor can be made to be, which in turn limits the ability to improve Q. There are also limits. Furthermore, it is also conceivable to form a coil conductor overlappingly on the upper surface of the coil conductor to increase the film thickness. However, in this case, it is necessary to precisely overlap a very thin coil conductor with a line width of several tens of μm and a coil conductor of the same size, which is difficult to manufacture.

The present invention has been made in view of the above-mentioned conventional situation, and an object of the present invention is to provide a high-frequency coil that can improve Q without increasing the film thickness of the coil conductor or widening the line width.

[Means for solving problems]

The inventors of the present invention connected multiple high-frequency coils in parallel in order to reduce the conductor resistance of the coil conductor.
Although the conductor resistance could be reduced, the inductance was also reduced, and in the end, no improvement in Q could be achieved. On the other hand, when multiple coil conductors were formed in parallel with an insulating substrate in between, and each coil conductor was made to face each other so that current flowed in the same direction as the current direction of the coil conductor, the conductor resistance was determined by the amount of decrease in inductance. It was found that the amount of decrease in inductance increases, and Q is increased by the amount that can suppress this decrease in inductance.
The present invention was completed based on the idea that this could be improved.

Therefore, in the present invention, a coil conductor is formed on the surface of an insulating substrate, and a coil conductor is formed on both edges of the insulating substrate.

forming output electrodes, each electrode having one end of the coil conductor;
and the other ends thereof are connected, at least one pair of coil conductors are formed to face each other with the insulating substrate in between, and one end and the other end of the plurality of coil conductors are respectively connected to the input and output electrodes. However, it is characterized in that the currents flowing through the plurality of coil conductors are in the same direction.

Here, the high frequency coil of the present invention is one in which coil conductors are formed on both main surfaces of one insulating substrate, or one in which one coil conductor is formed on the surface of an insulating substrate, and an insulating layer is formed on the upper surface of the coil conductor. This includes a multilayer structure in which coil conductors and coil conductors are alternately stacked, and the coil conductors may be formed to face each other with an insulating substrate or an insulating layer in between.

Further, the method for forming the coil conductor is not particularly limited, and may be a sputtering method, an i-deposition method, an ion-blating method, a screen printing method, or the like.

[Effect]

According to the high-frequency coil according to the present invention, the coil conductors are formed so as to face each other with the insulating substrate in between, and the current direction in each coil conductor is made the same, so that the decrease in conductor resistance is greater than the decrease in inductance. , the Q can be improved by the relative increase in this value.

As a result, there is no need to increase the film thickness or line width of the coil conductor as in the past, and it is possible to avoid increasing the size of the component, and problems such as underetching due to the film thickness increase do not occur.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 are diagrams for explaining a high frequency coil according to an embodiment of the present invention.

In the figure, reference numeral 1 designates the chip-type high-frequency coil of this embodiment, which has spiral-shaped first coils on both main surfaces 2a and 2b of an insulating substrate 2 made of glass or ceramics. It is constructed by patterning the second coil conductors 3 and 4. Furthermore, U-shaped input and output electrodes 5.6 are formed on the left and right edges in the longitudinal direction of the insulating substrate 2, and the input electrode 5 on the left side of the drawing is provided with the first. The outer ends 3a and 4a of the second coil conductors 3 and 4 are connected. Furthermore, the insulating substrate 2
person, output voltage [1st except 5 and 6]. second coil conductor 3,
An insulating layer 7 made of polyimide or polyamide resin is formed on the surface of the first insulating layer 7.
．． Through holes 8 are formed in portions of the second coil conductors 3 and 4 facing the inner ends 3b and 4b. Further, a lead electrode 9 is formed on the upper surface of the insulating layer 7, and one end of the lead electrode 9 is connected to the first end through the through hole 8. Second
It is connected to the inner ends 3b, 4b of the coil conductor 3.4,
The other end is connected to the output electrode 6.

And the above 1. The second coil conductors 3 and 4 are opposed to each other with the insulating substrate 2 in between. Second
The arrangement is such that the currents flowing through the coil conductors 3.4 are in the same direction.

Next, a method for manufacturing the chip-type high-frequency coil 1 of this embodiment will be explained with reference to FIGS. 2 and 3.

(2) First, a Ti film 10a is formed on the entire surface of a mirror-polished insulating substrate (glass, crystallized glass, alumina, etc.) 2 by sputtering to improve adhesion to the substrate 2. Subsequently, a Ti-Ag film 10b is formed on the surface of this Ti film 10a by a binary sputtering method, and an Ag film 10C is further formed on the surface of the Ti-Ag film 10b.
A conductor film 10 having a three-layer structure is formed by forming the conductor film 10 by the same sputtering method (see FIGS. 3(at) and 3(b)).

(2) Next, although not shown, on the amphibian surfaces 2a and 2b of the insulating substrate 2 (the conductor film 10 is not shown),
1st. A mask designed according to the shape of the second coil conductor, the person, and the output electrode is covered, and then an etching process is performed.Then, the part without the mask is removed, and the first coil conductor is covered with a mask designed according to the shape of the output electrode. A second coil conductor 34 and an output electrode 5.6 are formed. This results in the above 1. The second coil conductors 3.4 are arranged to face each other with the substrate 2 in between (Fig. 2(a)).
b) and Figure 3 IC)).

■ Subsequently, the entire surface of the amphibatic surfaces 2a and 2b of the insulating substrate 2 is coated with photosensitive polyimide resin to form an insulating film 7a.
are formed and dried (see FIG. 3+dl). Next, the above-mentioned electrodes, output electrodes 5, 6, etc. of this insulating film 7a are formed. and the inner end 3b of each coil conductor 3.4.

Exposure and development are performed only on the portion facing 4b, and this exposed portion remains, and the other portions are removed to form the insulating layer 7. As a result, the output electrodes 5.6 are exposed, and through holes 8 are formed at the inner ends 3b and 4b of the insulating layer 7 (see FIG. 3 (81)).

(2) Finally, a conductor film is formed on the upper surfaces of both insulating layers 7 by sputtering, and lead electrodes 9 are formed in the same manner as in step (2) above to form each inner end 3b.

4b and the output electrode 6 are connected. As a result, the high frequency coil 1 of this embodiment is formed (see FIG. 2 fc)).

In addition, in the above step (2), when connecting the inner ends 3b, 4b of each coil conductor 3°40 and the output electrode 6, both are made of Au.
A method of connecting by wire bonding and fixing this with a nylon or epoxy resin adhesive may also be adopted.

Next, the effects of this embodiment will be explained.

According to the chip-type high-frequency coil 1 of this embodiment, the first... forming a second coil conductor 3.4, the good conductor 3.4;
The outer ends 3a and 4a of the coil were connected to the input electrode 5, and the inner ends 3b and 4b were connected to the output electrode 6, so that the current flowed in the same direction as the current direction of each coil conductor 3. Therefore, the conductor resistance can be reduced to approximately half, and the decrease in inductance can be suppressed, and the Q can be improved accordingly. By the way, when only one coil conductor is formed on an insulating board with a board thickness of 0.64 mm, the L value is 18 nH and the Q value is 30 (
at400MHz), but in the structure of this example,
L value 10.5nH and Q value 35 (a t400MHz)
As a result, Q was improved by approximately 15%.

In addition, in this embodiment, a first film is formed on the amphibatic surface of the insulating substrate 2 by thin film technology. Since it is only necessary to form the second coil conductors 3 and 4 facing each other, there is no need to increase the film thickness or line width of the coil conductors as in the past, and it is possible to avoid increasing the size of the component and prevent underetching etc. No problems will arise.

Here, the high-frequency coil 1 of this embodiment can have a greater effect if adopted when it is desired to increase the film thickness and line width of the coil conductor as much as possible and further reduce the conductor resistance to improve the Q. can get.

Note that in the above embodiment, the first and second
The explanation has been given using the case where the coil conductor 3.4 is formed as an example, but in the present invention, after forming one coil, an insulating layer is formed on the part excluding the input and output electrodes, and the coil conductor is formed on the upper surface of the insulating layer. Alternatively, a multilayer coil may be formed by repeatedly forming an insulating layer and a coil conductor.

Furthermore, although the above-mentioned embodiments take a spiral type coil conductor as an example, the present invention is of course not limited to this, and can also be applied to, for example, a meander type coil conductor.

〔Effect of the invention〕

As described above, according to the high frequency coil according to the present invention, the coil conductors are formed to face each other with the insulating substrate in between, and the current flowing through both coil conductors is in the same direction, so that the film thickness of the coil conductor is This has the effect of improving Q without increasing the line width.

[Brief explanation of drawings]

1 to 3 are diagrams for explaining a high-frequency coil according to an embodiment of the present invention, and FIG. 1 is a perspective view thereof;
Fig. 2(a) is a plan view, Fig. 2(b) is a bottom view, Fig. 2(c) is a cross-sectional view, and Fig. 3) to fe
) are cross-sectional views for explaining the method of manufacturing the high-frequency coil of this example. In the figure, l is a high frequency coil, 2 is an insulating substrate, 3.4
is the first. The second coil conductor, 3a and 4a are the outer ends (one end) of the coil conductor, 3b and 4b are the inner ends (other end) thereof, and 5.6 is the output electrode.

Claims (1)

[Claims] (1) In a high-frequency coil in which a band-shaped coil conductor is patterned on the surface of an insulating substrate, and input and output electrodes to which one end and the other end of the coil conductor are connected are formed on both edges of the insulating substrate. , at least a pair of coil conductors are formed to face each other with the insulating substrate in between, and one end and the other end of the plurality of coil conductors are connected to the input and output electrodes, respectively, so that a current flows through the plurality of coil conductors. A high-frequency coil characterized in that it is configured to be oriented in the same direction.