JPH05304030A - Tri-plate line inductor and manufacturing method thereof - Google Patents

Abstract

PURPOSE:To assure the connection of the circuit patterns of adjacent two basic blocks to underneath conductors for enhancing the reliability and mass productivity by a method wherein said circuit patterns are connected between both basic blocks and mutually point-symmetrized to one point on a cut line. CONSTITUTION:The inner conductors 11a, 11b in one circuit pattern are continuously extended to the other circuit pattern so that the extended ends of respective inner conductors 11a, 11b may constitute the frequency adjusting auxiliary electrodes 12b, 12a in the other pattern. Next, a green sheet 13 on an upper side inductor is stacked to make gaps 14. Next, after the formation of an output terminal, etc., the whole body is to be baked. Later, respective basic blocks are cut off along the snapped lines 14. In such a constitution, in order to exhibit the same structure of the adjacent two circuit patterns after they are cut off, only the circuit patterns comprising the inner conductors 11a, 11b and the auxiliary electrodes 12b, 12a are required to be mutually point-symmetrized to the middle point 16 of the snapped line 15 of these two basic blocks.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distributed constant line inductor composed of a triplate line, and more particularly to a triplate line inductor whose inductance can be adjusted and a manufacturing method thereof.

[0002]

2. Description of the Related Art Recently, the frequency of mobile communication has moved to a high frequency side in order to respond to an increase in communication volume with the spread of mobile phones and the like. It is about to be developed. In this way, the frequency used shifts to the higher frequency side (shorter wavelength side), and with the widespread use of devices, there is a strong demand for miniaturization of wireless devices.

In this type of mobile communication, a large number of channels must be incorporated within a narrow frequency range, so that the communication equipment is required to have high frequency stability. As a method for this purpose, an oscillator (frequency synthesizer) that stabilizes the oscillation frequency of the voltage controlled oscillator by a phase locked loop (PLL) circuit as compared with a highly stable crystal oscillator is used. FIG. 4 shows a general configuration of such a frequency synthesizer. In the figure, 40 is a voltage controlled oscillator, 41 is a down counter, 42 is a PLL circuit, and 43 is a highly stable crystal oscillator. The frequency stability of the oscillator circuit is determined by the frequency stability performance of the voltage controlled oscillator, and the most important determining factors are the resonance frequency and the Q value of the voltage controlled oscillator circuit.

In response to the demand for miniaturization of radio equipment, development of a voltage controlled oscillator by a hybrid integrated circuit system using a multi-layer dielectric substrate in order to maintain the stability of the oscillation frequency is in progress. The resonance circuit of the oscillator of this system is composed of an inductance by a distributed constant type line, a lumped constant type capacitance, and a capacitance circuit by a varactor diode. FIG. 5 shows a resonance circuit having a triplate line structure as an example of such a resonance circuit. In the figure, 50 is an inner conductor that constitutes an inductor, 51 is a dielectric that sandwiches the inner conductor 50, and ground conductors 52 are provided on the upper and lower surfaces 51a and 51b of the dielectric 51 and on the side surface 51c of the substrate. ing. One end of the inner conductor 50 is connected to an external circuit via the output terminal 53, the blocking capacitor 54, and the varactor 55. The other end 50a of the inner conductor 50 is short-circuited to the ground conductor 52 on the substrate side surface 51c.

When such an integrated circuit is manufactured by a method of printing a conductor on a dielectric substrate, manufacturing variations occur in the inductance as well as the capacitance due to the deviation of the dielectric constant and the printing size. When adjusting the center frequency, the capacitance value can be adjusted by removing one of the electrodes of the capacitance, so the ground conductor exposed outside the circuit may be removed. However, in the inductor, the inductance cannot be adjusted unless the central conductor in the center of the triplate line is cut.Therefore, increase the capacitance value and expand the adjustment range, and adjust the variations of both with the capacitance. There are many. If the capacitance is increased, the oscillation frequency variable range of the varactor becomes relatively narrow, making it difficult to operate the device. In order to widen the variable frequency range of the varactor as much as possible, a mechanism for adjusting the manufacturing variation of the inductance is required as an auxiliary means for adjusting the center frequency of the resonance circuit.

As described above, in the multilayer dielectric substrate circuit, the inductance is composed of the triplate line with one end short-circuited. In this way, the impedance Z of the triplate strip line short-circuited at one end is given by the following equation (1), where Z ₀ is the characteristic impedance of the line.

[Equation 1]

For a line having a line length shorter than ⅛ wavelength with one end short-circuited, the formula (1) is simplified to the formula (2) below, which shows the property of inductance.

[Equation 2]

In the TEM mode line, the characteristic impedance Z ₀ is expressed by the following formula (3) by the capacitance C _u per unit length of the line, and it can be seen that the characteristic impedance is inversely proportional to the line capacitance. Z ₀ = (1 / c ₀ ) C _u (3)

Therefore, if the capacitance of the line is reduced, the line inductance will increase.

The resonant frequency of the resonant circuit can be fine-tuned by the lumped constant capacitance. Therefore, it suffices if the inductance can be adjusted in discrete steps in consideration of the range of manufacturing variations. The structural conditions necessary for the variable inductance mechanism in consideration of these are: (a) an auxiliary electrode that increases the capacitance of the line is provided near the short-circuited portion of the line, and (b) the auxiliary electrode is easy from the short-circuited portion. And (c) the electromagnetic field from the separated auxiliary electrode does not easily leak to the outside of the substrate, and (d) the auxiliary electrode can be formed on the dielectric substrate by a plane printing method.

Regarding the inductor whose inductance can be adjusted to satisfy such a condition, the present applicant has already proposed a triplate line inductor whose example is shown in FIG. 6 (Japanese Patent Application No. 4-21643). That is, one end of the inner conductor 63 that opposes the ground conductors 60 and 61 via the dielectric 62 between the pair of parallel ground conductors 60 and 61 is short-circuited to the ground conductor 65 on the side surface 64 of the substrate. In the distributed constant inductor, at least one auxiliary electrode 66 that is connected to the ground conductor 65 and is capable of disconnecting this connection is provided near the short-circuited portion of the inner conductor 63. Although the auxiliary electrode 66 is short-circuited with the ground conductor 65 on the side surface 64 of the substrate at the time of manufacturing as shown in FIG. 7A, a part 65a of the ground conductor 65 is removed as shown in FIG. The inductance can be adjusted by separating the electrode 66 from the ground conductor 65.

[0012]

When mass-producing such a multi-layered dielectric substrate integrated circuit, there is a manufacturing method in which a large number of circuit units are printed on a large dielectric sheet and then cut into circuit blocks after firing. It has been implemented. In order to simplify the cutting process, a snap method is used in which a cut is made in the dielectric green sheet before firing and the sheet is folded along this cut after firing.

When the inductance with the auxiliary electrode for adjustment is divided and cut by such a snap method, if the cut before firing and the position of the end of the inner conductor do not coincide with each other, the end of the inner conductor becomes a cut surface. The connection of this portion, which is not exposed and short-circuits one end of the strip line to the ground conductor, becomes uncertain, which leads to a decrease in Q value, an increase in variations in resonance frequency, and the like.
Since the green sheet is opaque, it was very difficult to match the snap line position before firing with the position of the inner conductor end.

Accordingly, the present invention provides a method for manufacturing a triplate line inductor and a triplate line inductor, which have high mass productivity and have extremely high reliability of a connection point to a ground conductor.

[0015]

According to the present invention, a plurality of circuits are formed on a dielectric so that the circuit patterns of adjacent basic blocks are continuous between the two basic blocks and are symmetrical with respect to one point on the cutting line. A method for manufacturing a triplate line inductor is provided in which a pattern is printed and a dielectric is cut into each substrate block after firing.

Each circuit pattern includes an inner conductor and an auxiliary electrode extending toward the cutting line, and the tip extension portion of the above-mentioned inner conductor in one adjacent basic block serves as an auxiliary electrode in the other basic block. It is preferably printed on.

It is also possible to insert snaps along the cutting line in the dielectric before firing and cut each basic block along the snaps after firing.

Further, according to the present invention, one end of the inner conductor facing the ground conductor with a dielectric interposed between a pair of parallel ground conductors is short-circuited to the ground conductor on the side surface of the substrate. Type inductor, which includes an auxiliary electrode which is arranged close to the short-circuited portion of the inner conductor and which can be connected to and disconnected from the ground conductor on the side surface of the substrate, and one end of the inner conductor and the auxiliary electrode on the side surface of the substrate are A triplate line inductor is provided that is symmetrically arranged with respect to a lateral centerline.

The line length of the inner conductor is 1 / the wavelength of the used frequency.
It is preferably less than 4.

[0020]

Since the circuit patterns of the adjacent basic blocks are continuous between both basic blocks and are point-symmetric with respect to one point on the cutting line, one end of the inner conductor and one end of the auxiliary electrode must be on the cutting surface. Will be exposed,
Ensures a reliable connection to the ground conductor. In addition, mass productivity also increases.

Further, since the one end of the inner conductor and the auxiliary electrode on the side surface of the substrate are arranged symmetrically with respect to the center line on the side surface of the substrate, the point-symmetrical manufacturing method as described above can be adopted.

[0022]

EXAMPLES Examples of the present invention will be described in detail below. Figure 1
FIG. 6 is a perspective view illustrating a method for manufacturing a triplate line inductor according to the present invention. As shown in the figure, when printing an inner conductor (resonance element) and an auxiliary electrode on a dielectric green sheet 10, two adjacent circuit patterns are treated as a pair, and the inner conductor 11a in one circuit pattern is treated as a pair. (1
1b) continuously extends to the other circuit pattern,
The extension tip of each inner conductor 11a (11b) has a frequency adjustment auxiliary electrode 12b in the other circuit pattern.
(12a) is configured.

Then, as shown in FIG. 2 (A), a green sheet 13 is stacked thereon as an upper dielectric layer to form cuts (snap lines) 14 and further output terminals and the like, and then the whole. Bake (eg 1 at 1000 ° C
0 minutes). As a result, the silver forming the inner conductor and the electrode melts in the closed state and becomes metallic silver, so that the electric resistance is sufficiently lowered and the Q value of the resonant element is increased.

After firing, each basic block is cut along snap lines 14 as shown in FIG. FIG. 3 shows a state in which the end portion 31 of the inner conductor and the end portion 32 of the auxiliary electrode are exposed on the cut surface 30 of each basic block after the snap cutting. As is apparent from the figure, the exposed ends of the end portion 31 of the inner conductor and the end portion 32 of the auxiliary electrode to the substrate cutting surface 30 are arranged symmetrically with respect to the center line 33 of the cutting surface 30.

After that, a ground conductor is formed on the upper and lower surfaces of the dielectric and also on the snap cut surface.

According to such a manufacturing method, the end portion of the inner conductor 11a (11b) and the auxiliary electrode 12 are formed on the snap cut surface.
Since the end of b (12a) is always exposed, reliable connection with the ground conductor can be achieved.

In order to make the two adjacent circuit patterns have the same structure after being cut, the inner conductor 11a (11b) and the auxiliary electrode 12b with respect to the center point 16 of the snap line 15 of these two basic blocks. It suffices that the circuit patterns composed of (12a) be point-symmetric with respect to each other. However, the center of symmetry does not necessarily have to be the center point 16 of the snap line 15, but the snap line length ±
It is preferably in the range of 20%.

In order to improve the Q value of the resonator, when the resonance element is closed and fired at a temperature equal to or higher than the melting point of the inner conductor metal, the frequency adjustment auxiliary electrode must be formed in the same plane as the resonance element. However, the present invention is particularly advantageous when manufacturing an adjustable inductor in this way.

[0029]

As described above in detail, according to the present invention, the circuit patterns of adjacent basic blocks are continuous between both basic blocks and are point-symmetric with respect to one point on the cutting line. Since one end of the inner conductor and one end of the auxiliary electrode are always exposed on the cut surface, the connection to the ground conductor is ensured, the reliability is improved, and the mass productivity is also very high.

[Brief description of drawings]

FIG. 1 is a perspective view for explaining a manufacturing method of the present invention.

FIG. 2 is a perspective view for explaining the manufacturing method of the present invention.

FIG. 3 is a perspective view for explaining the manufacturing method of the present invention.

FIG. 4 is a block diagram showing a general configuration of a frequency synthesizer.

FIG. 5 is a partially cutaway perspective view showing a resonance circuit of a conventional triplate line structure.

FIG. 6 is a perspective view showing a conventional triplate line inductor.

[Explanation of symbols]

 10, 13 Green sheets 11a, 11b Inner conductors 12a, 12b Frequency adjustment auxiliary electrodes 14, 15 Snap line 16 Center point 30 Cut surface 31, 32 End part 33 Center line

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadao Fujii 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Corporation (72) Innovator Shinya Nakai 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Within the corporation

Claims (5)

[Claims] 1. A plurality of circuit patterns are printed on a dielectric so that the circuit patterns of adjacent basic blocks are continuous in both basic blocks and are point-symmetric with respect to one point on a cutting line, and after firing, the dielectrics are formed. A method for manufacturing a triplate line inductor, which comprises cutting each substrate block. 2. Each of the circuit patterns includes an inner conductor and an auxiliary electrode extending toward the cutting line, and a tip extension portion of the inner conductor in one adjacent basic block is an auxiliary electrode in the other basic block. The manufacturing method according to claim 1, wherein the manufacturing method is as follows. 3. The method according to claim 1, wherein the dielectric material before firing is snapped along a cutting line, and each basic block is cut along the snap after firing. Method. 4. A distributed constant type inductor constituted by a pair of parallel ground conductors, wherein one end of an inner conductor facing the ground conductor via a dielectric is short-circuited to the ground conductor on a side surface of a substrate. And an auxiliary electrode that is arranged close to the short-circuited portion of the inner conductor and that can be connected to and disconnected from the ground conductor on the side surface of the substrate, wherein one end of the inner conductor on the side surface of the substrate and the auxiliary electrode are A triplate line inductor, which is arranged symmetrically with respect to a center line on a side surface of a substrate. 5. The inductor according to claim 4, wherein the line length of the inner conductor is less than ¼ of a wavelength of a used frequency.