JP2004320460A - Micro strip line-waveguide transformer and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microstrip-waveguide transformer in which a substrate manufacturing process is simple and which has a low loss, and large degree of freedom of selecting the substrate and layer structure, and to provide a method for manufacturing the same. <P>SOLUTION: A waveguide probe pattern is provided on a first dielectric substrate on the surface of a multilayer substrate. Other substrate except the first dielectric substrate and an adhesive sheet for adhering between the substrates are cut out to match the shape of the waveguide. The substrate and the sheet are laminated to form a waveguide cavity in the multilayer substrate. A through hole operating as the wall of the waveguide is formed in a sufficiently narrow interval at the periphery of the waveguide cavity. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a microstrip line-waveguide converter using a multilayer substrate for transmitting microwave and millimeter-wave high-frequency signals, and a method of manufacturing the same.
[0002]
[Prior art]
Several examples are known as a method of forming a waveguide conversion part on a substrate having a microwave circuit constituted by a microstrip line. FIGS. 8 and 9 show examples of typical microstrip line-waveguide converters using a multilayer substrate. Techniques related to these are disclosed in, for example, Japanese Patent Application Laid-Open No. 11-41010 (Patent Document 1). I have.
[0003]
8A and 8B are views showing an example of the structure of a multi-layer substrate of a microstrip line-waveguide converter using a conventional multi-layer substrate. FIG. 8A is a top pattern diagram, and FIG. (C) is a bottom pattern diagram. On the surface of the first dielectric substrate 2 constituting the multilayer substrate, an upper surface pattern including an open-ended microstrip line 1a functioning as a waveguide probe and a ground-side conductor pattern 1b is formed. On the back surface, a second metal foil layer 3 from which the metal foil corresponding to the inside of the waveguide is removed is formed in a laminated manner. On the back surface of the second dielectric substrate 5 constituting the multilayer substrate, a third metal foil layer 6 from which the metal foil corresponding to the inside of the waveguide is removed is laminated. Then, the first dielectric substrate 2 and the second dielectric substrate 5 are bonded with an adhesive sheet 4. Around the portion corresponding to the inside of the waveguide, through holes 9 penetrating through the multilayer substrate are arranged at intervals sufficiently narrow with respect to the wavelength of the frequency of the input / output high-frequency signal. In the microstrip line-waveguide converter having such a structure, since the conversion loss due to the dielectric loss of the first and second dielectric substrates 2 and 5 becomes large, the loss is caused in all the dielectric substrates constituting the multilayer substrate. It is necessary to use an expensive high-frequency substrate with less noise.
[0004]
9A and 9B show another example of a multilayer substrate of a microstrip line-waveguide converter using a conventional multilayer substrate. FIG. 9A is an upper surface pattern diagram, FIG. 9B is a sectional view taken along a waveguide probe, (C) is a bottom pattern diagram. A waveguide conversion portion is formed by forming a waveguide probe pattern 25a in the inner layer of a multilayer substrate, and cutting out the adhesive sheet 24, the third dielectric substrate 23, and the fourth metal foil layer 22 which are on the upper surface thereof. . In the figure, 26 is a fourth dielectric substrate (corresponding to 2 in FIG. 8), 27 is a fifth metal foil layer (corresponding to 3 in FIG. 8), 28 is an adhesive sheet (corresponding to 4 in FIG. 8), and 29 is Reference numeral 5 denotes a dielectric substrate (corresponding to 5 in FIG. 8), and reference numeral 30 denotes a sixth metal foil layer (corresponding to 6 in FIG. 8). In order to realize such a structure, after the waveguide probe pattern 25a is formed first, the third dielectric substrate 23, the adhesive sheet 24, the fourth dielectric substrate 26, the adhesive sheet 28, the fifth dielectric The substrate 29 is laminated, and thereafter, the hole processing of the through hole 9, the plating of the inner wall of the through hole, and the formation of the surface pattern can be performed in this order. However, in order to prevent the plating metal from adhering to the notched and exposed fourth dielectric substrate 26, for example, a step of filling and removing the resin in the notched portion is also required, and there is a problem that the manufacturing process becomes complicated. Was.
[0005]
[Problems to be solved by the invention]
As described above, in the case where the waveguide conversion unit is configured without notching the substrate, an expensive high-frequency substrate with low loss is selected for substrate materials other than the substrate on which the waveguide probe pattern is formed. Needed. Even if a high-frequency substrate is used, an increase in conversion loss is inevitable due to the presence of a dielectric around the waveguide probe. In order to further reduce the loss, it is necessary to make the dielectric portion as thin as possible. However, the number of layers of the substrate, the thickness of the substrate, and the like are limited, and there is a problem that the degree of freedom in design is reduced.
Further, when the waveguide probe pattern is formed on the inner layer substrate and the upper layer substrate is cut out, a special process is required to form the cutout portion, and the process becomes complicated.
[0006]
An object of the present invention is to solve the above problems and to provide a microstrip-waveguide converter having a simple substrate manufacturing process, low loss, high substrate selection, and a high degree of freedom in layer configuration, and a method of manufacturing the same. I do.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a microstrip line-waveguide converter using a microstrip line for transmitting a high-frequency signal and a multilayer substrate for converting a waveguide. The multilayer substrate has a waveguide probe pattern including a microstrip line and an open-end microstrip line formed by a metal foil layer on a dielectric substrate on the surface, and a waveguide around the waveguide probe pattern. In a position corresponding to the tube wall, through-holes arranged at sufficiently small intervals with respect to the wavelength of the frequency of the high-frequency signal, and another substrate laminated on the back surface of the dielectric substrate are formed into a waveguide shape. And a housing having a waveguide short-circuited surface at a distance of about １ ／ wavelength of the frequency of the high-frequency signal from the waveguide probe pattern, In another housing having a waveguide output aperture to match the shape of the sinus portion, and is characterized in that said multilayer substrate is held.
[0008]
The invention according to claim 2 is the microstrip line-waveguide converter according to claim 1, wherein the multilayer substrate has a thickness of approximately ４ wavelength of the frequency of the high-frequency signal, and the cavity has a flat plate shape. The multilayer substrate is sandwiched by another housing having a waveguide output opening adapted to the shape of the cavity by forming the waveguide short-circuit surface by covering with a housing. To do.
[0009]
According to a third aspect of the present invention, in the method of manufacturing a microstrip line-waveguide converter using a multilayer substrate for converting a microstrip line for transmitting a high-frequency signal and a waveguide, the step of forming the multilayer substrate Preparing a dielectric substrate in which a first metal foil layer is laminated on one surface and a second metal foil layer is laminated on the back surface, and the second metal foil layer of the dielectric substrate is formed into a waveguide shape. Step of removing together, preparing another substrate, and an adhesive sheet for bonding the back surface of the dielectric substrate and the another substrate, and aligning the another substrate and the adhesive sheet with the shape of the waveguide. Notching step, forming a multilayer substrate in which the dielectric substrate and the another substrate are bonded with the adhesive sheet, and positions corresponding to peripheral waveguide tube walls cut in the shape of the waveguide. The frequency of the high-frequency signal Forming through-holes arranged at sufficiently small intervals with respect to the length; and patterning at least the first metal foil layer to form a waveguide probe pattern. It is.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. 1A and 1B are structural views of a multilayer substrate constituting a microstrip line-waveguide converter of the present invention. FIG. 1A is a top view pattern diagram, FIG. 1B is a cross-sectional view along a waveguide probe, and FIG. Is an inner layer pattern diagram, and (d) is a lower surface pattern diagram. On the surface of the first dielectric substrate 2 constituting the multilayer substrate, an upper surface pattern including an open-ended microstrip line 1a functioning as a waveguide probe and a ground-side conductor pattern 1b is formed. On the back side, a second metal foil layer 3 from which the corresponding metal foil in the waveguide tube has been removed (the inner layer pattern) is formed in a laminated manner. On the back surface of the second dielectric substrate 5 constituting the multilayer substrate, a third metal foil layer 6 from which the metal foil corresponding to the inside of the waveguide is removed (the above-described lower surface pattern) is formed by lamination. Then, the first dielectric substrate 2 and the second dielectric substrate 5 are bonded with an adhesive sheet 4.
[0011]
In the present invention, the dielectric substrate other than the first dielectric substrate 2 forming the waveguide probe pattern 1a is cut out at a portion corresponding to the inside of the waveguide according to the shape of the waveguide. A waveguide cavity 10 having the dielectric substrate 2 as an upper surface is formed. Further, around the waveguide cavity 10, through holes 9 are arranged at intervals sufficiently short with respect to the wavelength to be used, and function as a waveguide wall. The through holes 9 arranged along the waveguide probe in the figure prevent the electromagnetic energy inside the waveguide from leaking into the space on the side of the microstrip line without coupling to the probe. It is formed as a shield for preventing radiation from the strip line to the outside and inflow of a noise signal from the outside to the microstrip line.
[0012]
Next, a microstrip line-waveguide converter in which an external waveguide is coupled to the multilayer substrate shown in FIG. 1 will be described with reference to FIGS. FIGS. 2A and 2B show the structure of a microstrip line-waveguide converter using the multilayer substrate of the present invention. FIG. 2A shows a case 13 having a quarter-wavelength short-circuited waveguide section 14, and FIG. 2) is a perspective view of the multilayer substrate shown in FIG. 1, and FIG. 2C is a perspective view of a housing 11 having a waveguide output unit. FIGS. 3A, 3B, and 3C are cross-sectional views respectively corresponding to the waveguide probe in the perspective views of FIGS. 2A, 2B, and 2C. In order to couple an external waveguide to the multilayer substrate, as shown in FIGS. 2 and 3, a 1/4 having a short-circuit surface at a position corresponding to approximately 1/4 wavelength of the wavelength of the high-frequency signal from the waveguide probe. The housing 12 having the wavelength short-circuited waveguide section 14 and the waveguide output section is configured such that the opening 12 is disposed at a position corresponding to the waveguide cavity 10 of the multilayer substrate and is sandwiched therebetween.
[0013]
4A and 4B are diagrams showing another embodiment of the present invention, wherein FIG. 4A is a cross-sectional view of a waveguide output unit casing, FIG. 4B is a cross-sectional view of a multilayer substrate with a quarter-wavelength cavity, and FIG. () Is a sectional view of a flat metal plate. This embodiment takes advantage of the advantage that the material and thickness of the second and third substrates do not affect the conversion loss, which is an advantage of the present invention, and reduces the thickness of the entire substrate to approximately 波長 wavelength of the frequency of the high-frequency signal. (Λg / 4), the lower opening surface of the waveguide cavity 10 is covered with the flat metal plate 13a to form a short-circuit surface of the waveguide. With such a configuration, a processing step for forming the housing 13 having the quarter-wavelength short-circuited waveguide section 14 becomes unnecessary. Further, the metal plate 13a may be a printed circuit board whose back surface serves as a grounding surface, and can also be formed by soldering in a later process, thereby increasing the degree of freedom in designing the housing structure. In this case, the external waveguide input / output unit casing 11 is disposed above the waveguide probe pattern 1a on the surface of the first dielectric substrate at a position integral with the waveguide cavity 10.
[0014]
In FIG. 4, reference numerals 7a, 7b, and 7c denote dielectric substrates, respectively, which indicate that a plurality of dielectric substrates are bonded to adjust the distance from the waveguide probe pattern 1a to the short-circuit surface. Reference numeral 8 denotes a metal foil film.
[0015]
FIGS. 5A and 5B show still another embodiment of the present invention. FIGS. 5A and 5C respectively show a quarter wavelength short-circuited waveguide section casing 13 and a waveguide output along a waveguide probe. It is sectional drawing of part housing | casing 11. FIG. (B) is a cross-sectional view of the substrate, and a metal plate 20 having a portion corresponding to a waveguide cavity 21 cut out on the back surface of a first dielectric substrate 2 having a waveguide probe pattern 1a with an adhesive sheet 19. It has a structure in which a laminated multilayer substrate is formed. When a semiconductor device that generates a large amount of heat is mounted on a dielectric substrate, the heat dissipation effect is enhanced by stacking the metal plates 20 in this manner. In order to configure a microstrip line-waveguide converter by coupling an external waveguide, as in FIG. What is necessary is just to arrange | position at the position which opposes across the waveguide cavity part 21 of a multilayer substrate.
[0016]
Next, the manufacturing method of the present invention will be described by taking, as an example, a method of manufacturing a multilayer substrate used in the microstrip line-waveguide converter described in FIG. First, as shown in FIG. 6, a first dielectric substrate 2 having a first metal foil layer 1 formed on the front surface and a second metal foil layer 3 formed on the back surface is prepared. A resist film 15 is attached to the surface of the second metal foil layer 3 on the back surface of the first dielectric substrate 2 (step a). A portion corresponding to the inside of the waveguide of the second metal foil layer 3 is removed through processes such as mask exposure, development, etching, and resist peeling (step b). This step b can be omitted when removing the second metal foil layer 3 at the same time as the metal pattern 17 in the step i described later. On the other hand, the connection sheet 4 is prepared independently and independently of this step, and a hole is formed in the connection sheet 4 using an end drill 16 for router processing or the like. This hole constitutes a waveguide cavity when a multilayer substrate is formed in a later step (step c). When this adhesive sheet is of a low flow type having a small resin flow, it is possible to prevent the resin from adhering to the first dielectric substrate 2 side. Further, the second dielectric substrate 5 on which the third metal foil layer 6 is formed is prepared, and a hole is formed in the second dielectric substrate 5 and the third metal foil layer 6 using an end drill 16 for router processing or the like. I do. This hole also forms a waveguide cavity when a multilayer substrate is formed in a later step (step d).
[0017]
In order to set the thickness of the entire multilayer substrate to １ ／ wavelength depending on the form of the waveguide converter, the second dielectric substrate 5 may be a multilayer substrate in which a plurality of dielectric substrates are laminated. 4), and a metal plate (corresponding to the metal plate 20 in FIG. 5). Next, the members (the first dielectric substrate, the adhesive sheet, and the second dielectric substrate) are arranged so that the portions corresponding to the cut-out portions in the waveguide tube are aligned, and are heated and compressed to be bonded (step e). .
[0018]
Next, as shown in FIG. 7, through-hole holes are formed in the bonded substrates, and the inner wall of the through-hole is plated to form a through-hole 9. In this case, the inner wall of the waveguide cavity 10 is plated to perform no special treatment, and the metal pattern 17 is formed. Next, a resist film 18 is attached to the front and back surfaces (step g). Then, a mask for forming a pattern is aligned with the resist film 18, and the resist film 18 other than the pattern to be left is removed by exposing and developing (step h). At this time, the resist is left in the through-hole 9 so that the metal in the inner layer is not etched, but the resist in the waveguide cavity 10 is removed. Subsequently, when an unnecessary portion of the metal is removed by pattern etching, the metal pattern 17 in the waveguide cavity 10 is also removed at the same time. Thereafter, the resist film 18 is removed (step i). Here, by appropriately adjusting the etching conditions, the second metal foil layer 3 performed in the above-described step b can be removed. Finally, a multilayer substrate can be formed through a solder resist formation, a plating step, and the like.
[0019]
By forming the microstrip line-waveguide converter of the present invention by such a manufacturing process, conversion loss due to dielectric loss of the dielectric substrate can be reduced, so that an expensive high-frequency substrate is used. There is no necessity, and the manufacturing cost can be reduced. According to the manufacturing method of the present invention, a desired structure can be formed only by bonding a plurality of substrates that have been processed in advance according to the shape of the waveguide, without using a special device or the like. This is a simple manufacturing method.
[0020]
【The invention's effect】
As described above, in the present invention, the first dielectric substrate on which the waveguide probe pattern is formed is a substrate on which a high-frequency circuit is formed, and it is necessary to select a high-frequency low-loss substrate. Since no other substrate is included inside the waveguide, even if a substrate having a large loss or a thick substrate is selected, the conversion loss does not increase, and the degree of freedom in substrate selection and layer configuration design is high.
[0021]
Further, when the thickness of the multilayer substrate is set to approximately 、 wavelength and the lowermost surface is covered with a flat metal plate, the structure is suitable for miniaturization and the machining is easy. Furthermore, the use of a multi-layer substrate formed by laminating metal plates achieves a high heat radiation effect when semiconductor devices such as transistors, FETs, and MMICs that generate a large amount of heat are used. Therefore, there is an effect that a high-efficiency high-output module can be produced at low cost.
[0022]
The manufacturing process of the multilayer substrate can be realized by the same process as the multilayer substrate forming process by a simple and ordinary tenting method. Further, since the number of processes is small and no special equipment or resin is used, productivity is high and reliability can be expected. In addition, the adhesive sheet for bonding between the substrates is cut out into a waveguide shape using a low-flow type resin having a small resin flow, thereby preventing the resin from adhering to the back surface of the first dielectric substrate and ensuring stable low-loss waveguide. A tube converter can be realized.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a multilayer substrate constituting a microstrip line-waveguide converter according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram of a microstrip line-waveguide converter according to an embodiment of the present invention.
FIG. 3 is an explanatory diagram of the microstrip line-waveguide converter shown in FIG. 2;
FIG. 4 is an explanatory diagram of a multilayer substrate constituting a microstrip line-waveguide converter according to another embodiment of the present invention.
FIG. 5 is an explanatory diagram of a multilayer substrate constituting a microstrip line-waveguide converter according to still another embodiment of the present invention.
FIG. 6 is an explanatory diagram of a method for manufacturing a multilayer substrate used in the microstrip line-waveguide converter of the present invention.
FIG. 7 is an explanatory diagram of a method for manufacturing a multilayer substrate used in the microstrip line-waveguide converter of the present invention.
FIG. 8 is an explanatory diagram of a multilayer substrate constituting a conventional microstrip line-waveguide converter.
FIG. 9 is an explanatory diagram of a multilayer substrate constituting another conventional microstrip line-waveguide converter.
[Explanation of symbols]
1: 1st metal foil layer, 1a: open end microstrip line, 1b: ground side conductor pattern, 2: first dielectric substrate, 3: second metal foil layer, 4: adhesive sheet, 5: second dielectric Substrate, 6: third metal foil layer, 9: through hole 10: waveguide cavity 11: housing, 12: opening, 13: housing, 14: 1/4 wavelength short-circuited waveguide

Claims (3)

A microstrip line-waveguide converter using a microstrip line transmitting a high-frequency signal and a multilayer substrate for converting a waveguide,
The multilayer substrate has a waveguide probe pattern including a microstrip line and an open-end microstrip line formed by a metal foil layer on a dielectric substrate on the surface, and a waveguide tube wall around the waveguide probe pattern. In a position corresponding to the above, a through through hole arranged at a sufficiently narrow interval with respect to the wavelength of the frequency of the high-frequency signal, and another substrate laminated on the back surface of the dielectric substrate in accordance with the shape of the waveguide. With a notched cavity,
Another housing having a waveguide short-circuit surface at a distance of about １ ／ wavelength of the frequency of the high-frequency signal from the waveguide probe pattern, and a waveguide output opening adapted to the shape of the cavity. A microstrip line-waveguide converter, wherein the multilayer substrate is sandwiched between a housing and the housing. 2. The microstrip line-waveguide converter according to claim 1, wherein the multilayer substrate has a thickness of about 波長 wavelength of the frequency of the high-frequency signal, and the cavity is covered by a flat casing. A microstrip line-waveguide, wherein the multilayer substrate is sandwiched by another casing having a waveguide short-circuit surface and a waveguide output opening adapted to the shape of the cavity. converter. In a method for manufacturing a microstrip line-waveguide converter using a multi-layer substrate for converting a microstrip line transmitting a high-frequency signal and a waveguide,
The step of forming the multilayer substrate,
A step of preparing a dielectric substrate having a first metal foil layer on one side and a second metal foil layer on the back side;
Preparing a step of removing the second metal foil layer of the dielectric substrate according to the shape of the waveguide, preparing another substrate, and an adhesive sheet for bonding the back surface of the dielectric substrate to the another substrate; And, a step of notching the another substrate and the adhesive sheet according to the shape of the waveguide,
A step of forming a multilayer substrate in which the dielectric substrate and the another substrate are bonded with the adhesive sheet,
Forming a through-hole at a position corresponding to a peripheral waveguide wall notched in the shape of the waveguide, at a sufficiently narrow interval with respect to the wavelength of the frequency of the high-frequency signal;
Patterning at least the first metal foil layer to form a waveguide probe pattern.

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