JPH04330805A - Dielectric triplate strip line resonance circuit and manufacturing method thereof - Google Patents

Abstract

PURPOSE:To prevent the crushing of an inner conductor or a core for an inner conductor, and to improve a Q value by printing a dielectric dummy at the edge of the inner conductor or the core for the inner conductor after printing them. CONSTITUTION:The dielectric whose thickness is more than that of an inner conductor 13, is printed as a dielectric dummy 21 so as to be connected with the edge of the inner conductor 13 printed on a dielectric sheet, then pressed after overlapping the dielectric sheet, burned after pressing it, and the cross section of the inner conductor 13 after the completion of burning is rectangular. And also, the dielectric whose thickness is more than that of a core 25 for inner conductor, is printed as the dummy so as to be connected with the edge of the core 25 printed on a dielectric sheet 12, then pressed after overlapping the dielectric sheet 12, and the cross section is formed of a rectangle hollow part by the thermal decomposition of the core 25 at the time of burning, so that the inner conductor 13 whose cross section is rectangular can be formed. Thus, the crushing of the inner conductor 13 or the core 25 can be prevented, and the high Q value can be realized.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric triplate stripline resonant circuit and a method for manufacturing the same, and more particularly to forming an inner conductor suitable for improving the Q value of the resonant circuit.

0002

2. Description of the Related Art Conventionally, a triplate strip line resonant circuit formed in a dielectric substrate has a larger effective dielectric constant than a microstrip line, resulting in a smaller element. Incorporating this resonant circuit into a multilayer dielectric substrate contributes to miniaturization of voltage controlled oscillators (VCOs) and frequency synthesizers. In addition, in the production of tri-plate strip line resonant circuits using multilayer dielectric substrates, the dielectric and the ground conductor and inner conductor that serve as the electrodes are simultaneously fired (referred to as the cofire method).
The aim is to reduce the size, improve reliability, and improve productivity. The manufacturing process of a dielectric triplate stripline resonant circuit using this conventional cofire method is shown in FIGS. 7a to 7f. Here, in order to simplify the diagram, waveguide mode suppressors and the like are omitted. The manufacturing process will be explained below with reference to FIGS. 7a to 7f.

First, as shown in FIG. 7a, a first layer is coated on a polyester film 11 by a first layer dielectric coating.
A layered dielectric sheet 12 is formed. Next, the inner conductor 13 is printed as shown in FIG. 7b.

Next, as shown in FIG. 7c, a second layer dielectric sheet 14 is formed on the first layer dielectric sheet 12 by a second layer dielectric coating. Next, the resonant circuit is separated, pressed and fired. That is, the polyester film 11 is cut off from the formed two-layer dielectric sheet,
Perform pressing and firing. This results in a two-layer dielectric substrate 15 as shown in FIG. 7d.

Next, as shown in FIG. 7e, ground conductors 16 are baked on the top and bottom of this two-layer dielectric substrate 15, and the input/output terminals 1
form 7. In this way, a two-layer dielectric triplate strip line is manufactured. By cutting this, a two-layer dielectric triplate stripline resonant circuit 18 as shown in FIG. 7f is completed.

FIG. 8 shows a structural diagram of a triplate strip line ring resonant circuit manufactured by such a cofire method. Here, 81 is a dielectric substrate, 82 is a ring-shaped inner conductor, 83 is an input/output terminal, and 84 is a ground conductor. FIG. 9 shows a comparison of the Q value measurement results between the triplate strip line ring resonant circuit shown in FIG. 8 and a microstrip line ring resonant circuit having approximately the same resonance frequency. Here, the tri-plate strip line ring resonant circuit used in the measurement has a dielectric constant ε of the dielectric substrate of 7.8, a substrate size of 55 mm x 45 mm x 1.4 mm, and an inner conductor diameter of 30 mm.
mm, and the inner conductor width is 1.0 mm. In addition, in the microstrip line ring resonant circuit, the dielectric constant ε of the dielectric substrate is
7.8, the board dimensions are 55 mm x 45 mm x 0.7 mm, the inner conductor diameter is 34 mm, and the inner conductor width is 1.0 mm. As is clear from Fig. 9, while the resonance frequencies are approximately equal,
The Q value for the triplate strip line resonant circuit is 98, and the Q value for the microstrip line resonant circuit is 15.
0, and the Q value of the triplate strip line resonant circuit is clearly low.

As part of the investigation into the reason for the low Q value, the cross-sectional shape of the inner conductor of the triplate strip line was investigated and the results are shown in FIG. The high frequency current density on the inner conductor of the strip line is distributed as shown by the broken line in FIG. As a result of the study, it was found that in cofired triplate strip lines, the inner conductor is pressed during the manufacturing process, which causes the edges to become thinner and the Q value to decrease. That is, since the current density is high in the edge portion, when this portion becomes thinner, the effective resistance of the inner conductor increases and the Q value decreases.

A known method for avoiding such troubles is to reduce the electrical resistance at the edges by forming the inner conductor in two or three layers, as shown in FIG.

[0009]

[Problems to be Solved by the Invention] However, when a triplate strip line is manufactured by the above-mentioned conventional method shown in FIG. The problem was that it was difficult to do so.

[0010] In addition, in order to achieve a high Q value in advance, the present applicant has formed the shape of the inner conductor as a core using a material that decomposes thermally when manufacturing the dielectric substrate, and when the dielectric is fired, the inner conductor is formed into a core. proposed a method of forming an inner conductor by press-fitting molten silver into the voids formed by thermal decomposition of the metal (Japanese Patent Application No. 3-2).
(See specification No. 9004). Such manufacturing method (process)
Examples are shown in FIGS. 12a to 12f. The manufacturing process will be explained below with reference to FIGS. 12a to 12f.

First, as shown in FIG. 12a, a first layer dielectric sheet 102 is formed on a polyester film 101 by first layer dielectric coating, and a shielding electrode 103 and an input layer are formed on the first layer dielectric sheet 102. Output terminal 10
4 and an inner conductor core (carbon) 105 are printed.

Next, as shown in FIG. 12b, a second layer dielectric sheet 106 is formed on the first layer dielectric sheet 102 by second layer dielectric coating, and a second layer dielectric sheet 106 is formed on the second layer dielectric sheet 106. Print the ground conductor 107. At this time, a bonding hole 108 is provided, and a pasting allowance (not shown) is set aside on the second layer dielectric sheet 106. Further, a third dielectric layer is formed on the second layer dielectric sheet 106 by the third layer dielectric coating.
A layer dielectric sheet 109 is formed, and a shielding electrode 110 and an inner conductor core (carbon) 111 are printed.

Next, as shown in FIG. 12c, a fourth layer dielectric sheet 112 is formed by a fourth layer dielectric coating.

Next, the elements are separated and fired. That is, the polyester film 101 is separated from the formed four-layer dielectric sheet and fired at a temperature below the sintering temperature (approximately 500° C.). As a result, as shown in FIG. 12d, an inner conductor cavity 113 is formed after the cores 105 and 111 are thermally decomposed and scattered. By press-fitting molten silver into the inner conductor hole 113, an inner conductor 114 having a thickness of about 30 μm and a length of about 10 mm can be formed.

Next, as shown in FIG. 12f, an outer ground conductor (for example, silver palladium) 115 and an input/output terminal 116 are connected.
is printed, and a short-circuit electrode 117 is formed on the side surface of the inner conductor on the open end side. In this way, metallic silver electrodes can be formed inside the dielectric substrate.

[0016] In the method of press-fitting silver to form the inner conductor as described above, a flexible material such as carbon paste is used as the core, so similar to the cofire method, the voids at the edges of the inner conductor are There was a problem in that the holes were crushed and became thinner, resulting in a lower Q value.

An object of the present invention is to solve these conventional problems and provide a dielectric triplate stripline resonant circuit and a method for manufacturing the same that improves the Q value by simply adding simple members or steps. There is a particular thing.

[0018]

[Means for Solving the Problems] In order to achieve the above object, the dielectric tri-plate strip line resonant circuit of the present invention includes an inner conductor printed on a dielectric sheet. After printing a dummy dielectric with a thickness greater than that of the inner conductor so that it touches the edge, the dielectric sheets are stacked and pressed, and after the pressing is fired, the inner conductor has a rectangular cross section after firing. There are certain characteristics.

In the dielectric triplate strip line resonant circuit, the width of the dummy is twice the thickness of the inner conductor.
The thickness of the dummy is 1.05 to 1.20 times the thickness of the inner conductor, and the dielectric constant of the dummy is equal to the dielectric constant of the dielectric sheet. The feature is that they are the same.

In the method for manufacturing a dielectric triplate stripline resonant circuit of the present invention, the inner conductor is printed on the dielectric sheet so as to be in contact with the edge of the inner conductor printed on the dielectric sheet. The method is characterized in that after printing a dummy dielectric material with a thickness greater than that of the conductor, the dielectric sheets are stacked and pressed, and then fired after the pressing.

Another dielectric tri-plate strip line resonant circuit of the present invention is a dielectric tri-plate strip line resonant circuit in which the thickness of the core is adjusted so as to be in contact with the edge of the core printed on the dielectric sheet. After printing the above dielectric as a dummy, dielectric sheets are stacked and pressed, and during firing, the core is thermally decomposed to form a hole with a rectangular cross section, and molten silver is press-fitted to form an inner conductor with a rectangular cross section. It is distinctive in that it is configured to form a

In the other dielectric triplate strip line resonant circuit, the width of the dummy is within 20 times the thickness of the inner conductor, and the thickness of the dummy is 1 times the thickness of the inner conductor. The dielectric constant of the dummy is set to be .05 times to 1.20 times or less, and the dielectric constant of the dummy is the same as the dielectric constant of the dielectric sheet.

Another method of manufacturing a dielectric tri-plate strip line resonant circuit according to the present invention is to form the shape of the inner conductor as a core using a material that decomposes thermally when manufacturing the tri-plate strip line resonant circuit using a dielectric substrate. In a method for manufacturing a dielectric triplate strip line resonant circuit in which an inner conductor is formed by press-fitting molten silver or the like into the voids formed by thermal decomposition of the core during dielectric firing, the dielectric sheet is After printing a dummy dielectric with a thickness greater than the thickness of the core so that it touches the printed edge of the core, the dielectric sheets are stacked and pressed, and the cross section becomes rectangular due to thermal decomposition of the core during firing. The feature is that an inner conductor having a rectangular cross section is formed by forming a hole.

[0024]

[Operation] In the present invention, a dielectric material having a thickness greater than the inner conductor is printed as a dummy in contact with the edge of the inner conductor printed on the dielectric sheet, and then the dielectric sheets are stacked and pressed. After pressing, it is fired.

Further, in the present invention, a dielectric material having a thickness greater than the thickness of the core is printed as a dummy so as to be in contact with the edge of the core printed on the dielectric sheet, and then the dielectric sheets are stacked and pressed. During firing, the core is thermally decomposed to form a cavity having a rectangular cross section, thereby forming an inner conductor having a rectangular cross section.

[0026] With these, it is possible to prevent the inner conductor or the core for the inner conductor from being crushed, and it is possible to realize a high Q value.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

(I) First Embodiment FIGS. 1a to 1d are diagrams for explaining a method of manufacturing a dielectric triplate strip line resonant circuit according to a first embodiment of the present invention. This shows the inner conductor forming step in the method for manufacturing the resonant circuit, and the other steps are the same as the manufacturing steps using the conventional cofire method shown in FIG. 7, so their explanation will be omitted.

In FIGS. 1a to 1d, 11 is a polyester film, 12 is a first layer dielectric sheet, 13 is an inner conductor, 14 is a second layer dielectric sheet, and 21 is a dielectric dummy characteristic of the present invention. be.

The inner conductor of the tri-plate strip line by the cofire method is manufactured by baking silver paste mixed with glass frit, and has a thickness of about 30 μm. The frequency range in which triplate stripline resonant circuits are used is from 800 MHz to 3 GHz. 800MHz
The skin thickness of the silver paste is approximately 5.3 μm. In order to prevent the Q value of the resonant circuit from decreasing due to resistance loss of the inner conductor, the thickness of the silver paste must be at least three times the thickness of the skin. On the other hand, since it is sufficient for the silver paste to be about 6 times the thickness, the conditions regarding the thickness are satisfied. Therefore, if the edges of the inner conductor are not crushed and thinned when the dielectric layers are stacked and pressed, the Q value can be prevented from decreasing. Therefore, in the first embodiment, after printing the inner conductor, a step of printing a dielectric dummy to surround the edge of the inner conductor is added to prevent the inner conductor from being crushed during pressing.

The formation of the inner conductor according to the first embodiment will be explained below.

First, as shown in FIG. 1a, a first layer is coated on the polyester film 11 by a first layer dielectric coating.
A layered dielectric sheet 12 is formed. Next, as shown in FIG. 1b, an inner conductor 13 is printed on the first layer dielectric sheet 12.

Next, in order not to crush the edge of the inner conductor 13,
A dielectric dummy 21 is printed in contact with the edge of the inner conductor 13 as shown in FIG. 1c. FIG. 2 shows a cross section of the first layer dielectric sheet 12 during this dielectric dummy printing. Here, the dielectric dummy 21 is printed thicker than the inner conductor 13 in a limited range on the side surface of the inner conductor.

Next, as shown in FIG. 1d, a second layer dielectric sheet 1 is placed on the dummy printed first layer dielectric sheet 12.
4 is placed and shaped, and then baked. FIG. 3 shows a cross section of the inner conductor after firing. As is clear from FIG. 3, the edges of the inner conductor 13 are not crushed due to the provision of the dielectric dummy 21. Therefore, the inner conductor has a rectangular cross section after firing.

By the method of the first embodiment, FIGS.
A ring resonant circuit with the same dimensions as the conventional tri-plate stripline ring resonant circuit shown in 1 was manufactured. The Q value was measured using this manufactured triplate strip line ring resonant circuit. The measured value is that the resonance frequency is 1174M
Hz, and the Q value was 162. As is clear from this result, if a tri-plate strip line is manufactured by printing dielectric dummies 21 on both sides of the inner conductor 13, a high Q value can be achieved even with a single-layer inner conductor.

Since the dimensions of the edge of the inner conductor are accurately defined by the dielectric dummy, it is possible to
If a dielectric dummy is printed on the end of the /2 wavelength resonant circuit, the resonant frequency can be accurately controlled.

Next, the above dielectric dummy will be explained in detail.

If the dielectric dummy has a higher dielectric constant than the dielectric sheet, the current density at the edge of the inner conductor increases, leading to a decrease in the Q value. On the other hand, if the dielectric constant is lower than that of the dielectric sheet, the effective dielectric constant of the line will decrease, so it will not contribute to miniaturization. Therefore, the dielectric dummy is preferably made of a material that exhibits the same dielectric constant as the dielectric sheet. Further, it was sufficient that the width of the dielectric dummy was about 20 times the thickness of the inner conductor. Preferably, it is sufficient to make it 20 times or less. Furthermore, if the thickness of the dielectric dummy is thinner than the thickness of the inner conductor, the inner conductor will collapse and the effect will be reduced, so it is desirable that the thickness of the dielectric dummy be thicker than the thickness of the inner conductor. However, if it is too thick, it may cause problems such as pressing on the upper layer substrate. As a result of the experiment, the thickness of the conductor ×
It was found that the effect was apparent from 1.05, and that if the thickness of the inner conductor was x 1.2, there would be no adverse effects such as pressing on the upper layer board.

(II) Second Example In this second example, the dielectric dummy used in the first example was replaced with a dielectric triplate strip line using the silver intrusion method previously proposed by the present applicant. By applying this method to a method for manufacturing a resonant circuit, the reduction in Q value is improved.

FIGS. 5a and 5b are diagrams for explaining a method of manufacturing a dielectric triplate strip line resonant circuit according to a second embodiment of the present invention. This shows the core forming process in the method for manufacturing the resonant circuit, and the other steps are the same as the manufacturing process using the silver intrusion method shown in FIG. 12, so their explanation will be omitted.

In FIGS. 5a and 5b, 11 is a polyester film, 12 is a first layer dielectric sheet, 25 is an inner conductor core, and 26 is a dielectric dummy characteristic of the present invention.

If the edges of the inner conductor core are not crushed and become thin when the dielectric layers are piled up and pressed, the edge of the press-fitted silver inner conductor will not become thin either, and a decrease in the Q value can be prevented. Therefore, in the second embodiment, after printing the inner conductor core, a step of printing a dielectric dummy to surround the edge of the core is added to prevent the inner conductor from being crushed during pressing.

The formation of the inner conductor core according to the second embodiment will be explained below.

First, as shown in FIG. 5a, a first layer is coated on the polyester film 11 by a first layer dielectric coating.
A layer dielectric sheet 12 is formed, and an inner conductor core 25 is printed on the first layer dielectric sheet 12.

Next, in order not to crush the edge of the inner conductor core 25, a dielectric dummy 26 is printed in contact with the edge of the inner conductor core 25, as shown in FIG. 5b. The cross section of the first layer dielectric sheet 12 when printing this dielectric dummy is the inner conductor 13 in FIG.
The shape is the same except that the core 25 for the inner conductor is replaced by the core 25 for the inner conductor. Here, the dielectric dummy 26 is printed thicker than the inner conductor core 25 in a limited range on the side surface of the inner conductor core.

Next, a second layer dielectric sheet (not shown) is formed on the first layer dielectric sheet 12 on which the dielectric dummy 26 has been printed, and is press-molded and then fired. FIG. 6 shows a cross section of the cavity 27 after the fired core is thermally decomposed. As is clear from FIG. 6, by providing the dielectric dummy 21, the edges of the cavity 27 into which the inner conductor is press-fitted are not crushed. Therefore, the inner conductor formed by silver press-in has a rectangular cross section. In this way, it is possible to prevent the edges of the inner conductor from being crushed due to the crushing of the core, so a high Q value can be obtained.

Since the dimensions of the edge of the core for the inner conductor can be precisely defined by the dielectric dummy, and the dimensions of the inner conductor can also be precisely defined, the 1/4 or 1/2 wavelength resonant circuit as shown in FIG. If dielectric dummies are printed on the ends as well, the resonance frequency can be accurately controlled.

Furthermore, since the dielectric dummy in the second embodiment is the same as that in the first embodiment, details such as the width and thickness of the dielectric dummy are the same as those in the first embodiment. Please refer to

In the first and second embodiments described above, since the dielectric dummy is printed after printing the inner conductor or the core for the inner conductor, there is no need to use a drawing device, which has the advantage of simplifying manufacturing. be.

[0050]

[Effects of the Invention] As explained above, according to the present invention,
By printing a dielectric dummy on the edges after printing the inner conductor or the core for the inner conductor, it is possible to prevent the inner conductor or the core from being crushed, thereby improving the Q value.

[Brief explanation of drawings]

1a to 1d are diagrams for explaining a method of manufacturing a dielectric triplate strip line resonant circuit according to a first embodiment of the present invention; FIG.

FIG. 2 is a diagram showing an example of dielectric dummy printing in the first embodiment of the present invention.

FIG. 3 is a sectional view of the inner conductor after firing the dielectric sheet.

FIG. 4 shows dielectric dummy printing on the end of a resonant circuit.

FIGS. 5a and 5b are diagrams for explaining a method of manufacturing a dielectric triplate stripline resonant circuit according to a second embodiment of the present invention; FIGS.

FIG. 6 is a sectional view of a hole portion after firing in a second embodiment of the present invention.

7a to 7f are process diagrams for manufacturing a dielectric triplate strip line resonant circuit using the conventional cofire method.

FIG. 8 is a structural diagram of a conventional dielectric triplate stripline ring resonant circuit.

FIG. 9 is a comparison diagram of Q values of various strip line resonant circuits.

FIG. 10 is a diagram for explaining a conventional problem.

FIG. 11 is a diagram showing an example of an inner conductor of a conventional multilayer structure.

12a to 12f are process diagrams for manufacturing a dielectric triplate stripline resonant circuit using a silver intrusion method previously proposed by the present applicant.

[Explanation of symbols]

11 Polyester film 12 First layer dielectric sheet 13 Inner conductor 14 Second layer dielectric sheet 21 Dielectric dummy 22 Dielectric substrate 23 Dielectric dummy 25 Core for inner conductor 26 Dielectric dummy

Claims (10)

[Claims] Claim 1: In a dielectric tri-plate strip line resonant circuit, a dielectric material having a thickness greater than that of the inner conductor is printed as a dummy in contact with the edge of the inner conductor printed on the dielectric sheet, and then the dielectric sheet is What is claimed is: 1. A dielectric tri-plate strip line resonant circuit characterized in that the inner conductor is stacked and pressed, and fired after the pressing, so that the inner conductor has a rectangular cross section after firing. 2. The width of the dummy is 2 times the thickness of the inner conductor.
2. The dielectric triplate stripline resonant circuit according to claim 1, wherein the dielectric triplate stripline resonant circuit is within 0 times. 3. The dielectric triplate strip line according to claim 1, wherein the thickness of the dummy is 1.05 to 1.20 times the thickness of the inner conductor. resonant circuit. 4. The dielectric constant of the dummy is the same as the dielectric constant of the dielectric sheet.
The dielectric triplate stripline resonant circuit according to claim 2 or 3. 5. In a method for manufacturing a dielectric tri-plate stripline resonant circuit, after printing a dummy dielectric material having a thickness greater than that of the inner conductor so as to be in contact with the edge of the inner conductor printed on the dielectric sheet. 1. A method for manufacturing a dielectric triplate strip line resonant circuit, comprising stacking and pressing dielectric sheets and firing after pressing. 6. In a dielectric tri-plate stripline resonant circuit, a dielectric material having a thickness greater than the thickness of the core is printed as a dummy so as to be in contact with the edge of the core printed on the dielectric sheet, and then the dielectric sheet is printed. are stacked and pressed, and during firing, the core is thermally decomposed to form a hole with a rectangular cross section, and by press-fitting molten silver, an inner conductor with a rectangular cross section is formed. Dielectric triplate stripline resonant circuit. 7. The width of the dummy is 2 times the thickness of the inner conductor.
7. The dielectric triplate strip line resonant circuit according to claim 6, wherein the dielectric triplate strip line resonant circuit is within 0 times. 8. The dielectric triplate strip line according to claim 6 or 7, wherein the thickness of the dummy is 1.05 to 1.20 times the thickness of the inner conductor. resonant circuit. 9. The dielectric constant of the dummy is the same as the dielectric constant of the dielectric sheet.
The dielectric triplate strip line resonant circuit according to claim 7 or claim 8. 10. When manufacturing a tri-plate strip line resonant circuit using a dielectric substrate, the shape of the inner conductor is formed as a core using a material that decomposes thermally, and the core is thermally decomposed during firing of the dielectric. In a method for manufacturing a dielectric tri-plate strip line resonant circuit in which an inner conductor is formed by press-fitting molten silver or the like into a hollow hole, a core is After printing a dummy dielectric with a thickness greater than or equal to , the dielectric sheets are stacked and pressed, and during firing the core is thermally decomposed to form a cavity with a rectangular cross section. A method of manufacturing a dielectric triplate stripline resonant circuit, comprising forming a conductor.