WO2018012368A1 - Waveguide filter - Google Patents

Abstract

A waveguide filter according to the present invention is provided with: a filter component provided with a first substrate including a filter pattern provided on a first surface of a first substrate body and a first metal film disposed on the outer peripheral portion of a second surface of the first substrate body and a metal case that delimits a hollow section, that is open at a side facing the filter pattern, and that is provided on the first surface side; a second substrate including a second metal film that is provided, on a first surface of a second substrate body having a through-hole facing the hollow section, around the through-hole and that is electrically connected to the first metal film with solder therebetween; and a metal substrate that is electrically connected to the second metal film and that has a recessed section at a portion facing the through-hole.

Description

Waveguide filter

The present invention relates to a waveguide filter.

A microwave circuit (hereinafter simply referred to as “MIC (Microwave Integrated Circuit)”) that constitutes a high-frequency circuit in the microwave or millimeter wave band is a dedicated package specialized for a specific frequency, and a semiconductor device such as a mixer or an amplifier. A high frequency module is configured by providing a ceramic substrate.
The MIC requires a dedicated and expensive high frequency package. The high-frequency package is manually soldered to a printed circuit board (hereinafter simply referred to as “substrate”) including a control circuit and the like. For this reason, the wireless communication device provided with the MIC is expensive.

In recent years, it has been desired to reduce the cost of wireless communication devices. For this reason, surface mounting (SMT (Surface mount technology)) of key devices such as frequency converters and amplifiers is also progressing in wireless communication devices used in a high frequency region.
When configuring a high-frequency circuit using such a surface-mount type device, a filter that suppresses unnecessary waves is usually formed on a substrate (for example, a Rogers substrate) including the circuit using a circuit pattern. .

However, generally, the formation accuracy of the circuit pattern on the substrate is low. For this reason, the above-described filter forming method is not suitable as a filter forming method having a highly accurate unnecessary wave suppressing function.
Therefore, in a related technique, when a highly accurate filter capable of suppressing unnecessary waves is required, a waveguide filter is used as a filter.

Patent Document 1 discloses a waveguide filter including a metal partition plate that narrows a cross section perpendicular to a wave traveling direction inside a waveguide.
Further, Patent Document 1 discloses that a box-shaped part including a partition plate in a drawing direction parallel to the surface in which a plane parallel to the wave traveling direction is open, and an outside of the filter using a conductor. It is disclosed that a substrate on which an output end is formed is prepared as a separate body, and that the component and the substrate are bonded so that the opening surface of the component and the surface on which the input / output end of the substrate is formed face each other. Yes.

Japanese Patent Laid-Open No. 2002-113112

By the way, when the waveguide filter described in Patent Document 1 is used in a high frequency region such as a microwave or a millimeter wave band, it is necessary to process a metal box-shaped component with high accuracy.
However, since it is technically difficult and complicated to process metal box-shaped parts with high accuracy, a waveguide having good characteristics in a high-frequency region such as a microwave or a millimeter wave band. There was a problem that a tube filter could not be realized.

An object of the present invention is to provide a waveguide filter having good filter characteristics in a high frequency region in view of the above-described problems.

In order to solve the above problems, a waveguide filter according to an aspect of the present invention includes a first substrate body, a filter pattern provided on a first surface of the first substrate body, and the first surface. A first substrate including a first metal film disposed on an outer peripheral portion of the second surface of the first substrate body located on the opposite side of the first substrate body, and a hollow portion extending in one direction, A filter case comprising: a metal case provided on a first surface side of the first substrate body, the side facing the filter pattern being open; and the hollow portion via the first substrate; A second substrate body having a penetrating portion in an opposing portion; and electrically provided through the first metal film and solder provided around the through portion of the first surface of the second substrate body. A second substrate including a second metal film to be connected; and a first surface of the second substrate body. A portion that includes a substrate placement surface on which the second surface of the second substrate body located on the opposite side is placed, is electrically connected to the second metal film, and is opposed to the penetrating portion. And a metal substrate having a recess.

According to the waveguide filter of the present invention, it is possible to accurately form a filter pattern using a metal film by providing a filter pattern that functions as a filter on the first surface of the first substrate body. In other words, since the metal processing that has been performed by the related technique is not required, good filter characteristics can be realized in the high frequency region.
The first metal film provided on the first substrate body and the second metal film provided on the first surface of the second substrate body and electrically connected to the first metal film via solder. By providing a metal film, it is possible to surface-mount the filter component with high positional accuracy on the second substrate using a mounting machine, so that good filter characteristics can be realized in the high frequency region. Can do.

1 is a perspective view showing a waveguide filter according to a first embodiment of the present invention. FIG. 2 is an exploded perspective view showing the waveguide filter shown in FIG. 1. FIG. 3 is a plan view showing an upper surface (front surface) of the first substrate shown in FIG. 2. It is a top view which shows the lower surface (back surface) of the 1st board | substrate shown by FIG. FIG. 3 is a cross-sectional view of the first substrate along the line CC in FIG. 2. FIG. 2 is a cross-sectional view of the waveguide filter along the line AA in FIG. 1. FIG. 3 is a plan view showing a second substrate shown in FIG. 2. FIG. 8 is a cross-sectional view of the second substrate along the line EE in FIG. 7. It is a perspective view which shows the waveguide filter which concerns on the 2nd Embodiment of this invention. FIG. 10 is an exploded perspective view showing the waveguide filter shown in FIG. 9. FIG. 10 is a cross-sectional view of the waveguide filter taken along line FF in FIG. 9. It is a graph which shows the relationship between the frequency in the waveguide filter shown by FIG. 1, an insertion loss, and a return loss.

Hereinafter, an embodiment to which the present invention is applied will be described in detail with reference to the drawings. The drawings used in the following description are for explaining the configuration of the embodiment of the present invention, and the size, thickness, dimension, etc. of each part shown in the figure are the dimensional relationships of the actual waveguide filter. May be different.

(First embodiment)
FIG. 1 is a perspective view of a waveguide filter according to a first embodiment of the present invention. FIG. 2 is an exploded perspective view of the waveguide filter shown in FIG.
Referring to FIGS. 1 and 2, the waveguide filter 10 of the first embodiment includes a filter component 11, a second substrate 13, and a metal substrate 14.
1 and 2, the X direction is the width direction of the hollow portion 33, the Y direction is the extending direction (length direction) of the hollow portion 33, and the Z direction is a direction orthogonal to the XY plane direction (first direction) The thickness direction of the board | substrate 16 and the 2nd board | substrate 13, or the height direction of the hollow part 33) is each shown.

In FIG. 2, a symbol B is a region (hereinafter referred to as “region B”) of the first substrate body 21 where the filter pattern 23 is formed, and a symbol L1 is a length of the hollow portion 33 (hereinafter “length L1”). The symbol H1 indicates the height of the hollow portion 33 (hereinafter referred to as “height H1”), and the symbol W1 indicates the width of the hollow portion 33 (hereinafter referred to as “width W1”). In FIG. 2, the same components as those shown in FIG.

FIG. 3 is a plan view of the upper surface side (front surface side) of the first substrate shown in FIG. In FIG. 3, the same components as those of the structure shown in FIG.
FIG. 4 is a plan view of the lower surface side (back surface side) of the first substrate shown in FIG. 4, the same components as those shown in FIGS. 2 and 3 are denoted by the same reference numerals.
FIG. 5 is a cross-sectional view of the first substrate shown in FIG. 2 taken along the line CC. In FIG. 5, the same components as those shown in FIGS. 3 and 4 are denoted by the same reference numerals.

FIG. 6 is a cross-sectional view of the waveguide filter shown in FIG. 1 cut along line AA. The cutting position (CC line) of the waveguide filter 10 shown in FIG. 6 corresponds to the cutting position (CC line shown in FIG. 2) of the first substrate 16 shown in FIG. In FIG. 6, the same components as those shown in FIGS. 1 to 5 are denoted by the same reference numerals.

With reference to FIGS. 1 to 6, the filter component 11 includes a first substrate 16 and a metal case 17.
The first substrate 16 includes a first substrate body 21, a filter pattern 23, a microstrip pattern 24, a first metal film 25 (FIG. 4), and a through electrode 27 (FIGS. 3 and 4). And having.

The first substrate body 21 is an insulating substrate extending in the Y direction. The first substrate body 21 has a first surface 21a and a second surface 21b.
The first surface 21a is a surface on the side where the metal case 17 is disposed. The second surface 21b is a surface disposed on the opposite side of the first surface 21a. The second surface 21b is a surface on the side where the second substrate 13 is disposed.
For example, the thickness of the first substrate body 21 may be smaller than the height H1 of the hollow portion 33 formed by the metal case 17.
Thus, by making the thickness of the first substrate body 21 smaller than the height H1 of the hollow portion 33, the electrostatic induction action of the first substrate body 21 becomes an obstacle when the high-frequency signal moves. This can be suppressed.
The dielectric constant of the first substrate body 21 is preferably 5 or less, for example.

As shown in more detail in FIGS. 3 to 5, the filter pattern 23 is formed on the first surface 21 a of the first substrate body 21 surrounded by the region B arranged at the center of the first substrate body 21. Is provided.
The filter pattern 23 can be formed, for example, by forming a metal film. As the metal film constituting the filter pattern 23, for example, a plating film (for example, an Au plating film or an Ag plating film) can be used.

The microstrip pattern 24 is provided on the first surface 21a of the first substrate body 21 located on both sides of the region B in the Y direction. The microstrip pattern 24 is electrically connected to the filter pattern 23 by being connected to the filter pattern 23. The microstrip pattern 24 can be formed of a metal film similar to the metal film that forms the filter pattern 23.

The first metal film 25 is disposed on the outer peripheral portion of the second surface 21 b of the first substrate body 21. As the first metal film 25, a metal film (for example, an Au plating film or an Ag plating film) on which the solder 31 can be placed is used.
Further, referring to FIG. 6, solder 31 is provided on one surface 25 a of the first metal film 25 (a surface facing the second substrate 13). The first metal film 25 is electrically connected to the second substrate 13 via the solder 31.

A plurality of through electrodes 27 are arranged to extend in the Y direction on both sides in the width direction (X direction) of the first substrate body 21. The through electrode 27 passes through the first substrate body 21. The through electrode 27 has one end connected to the filter pattern 23 or the microstrip pattern 24 and the other end connected to the first metal film 25.
Accordingly, the through electrode 27 is electrically connected to the filter pattern 23 and the microstrip pattern 24 and the first metal film 25.
The through electrode 27 can be made of a metal film similar to the first metal film 25, for example.

Referring to FIGS. 1, 2, and 6, the metal case 17 is U-shaped and extends in one direction (in this case, the Y direction). The metal case 17 defines a hollow portion 33 extending in one direction on the inner side. The shape of the hollow portion 33 can be, for example, a quadrangular prism.
As best shown in FIG. 6, the metal case 17 has an open end 17 </ b> A on the side facing the filter pattern 23 and the microstrip pattern 24.

The metal case 17 has a pair of connecting portions 35 extending in the Y direction on the open end 17A side. The pair of connection portions 35 are joined to the filter pattern 23 and the microstrip pattern 24 arranged on the first surface 21 a side of the first substrate body 21.
Thereby, the metal case 17 is electrically connected to the first substrate 16 and the second substrate 13.
The metal case 17 configured as described above constitutes the upper part of the waveguide of the waveguide filter 10.

FIG. 7 is a plan view of the second substrate shown in FIG. In FIG. 7, the same components as those shown in FIGS. 1, 2, and 6 are denoted by the same reference numerals. 1, 2, and 7, only a part of the second substrate 13 extending in the XY plane direction is shown.
FIG. 8 is a cross-sectional view of the second substrate shown in FIG. 7 cut along the line EE. In FIG. 8, the same components as those in the structure shown in FIG.

Referring to FIGS. 1, 2, and 6 to 8, the second substrate 13 includes a second substrate body 38, a second metal film 41, a pair of high frequency signal patterns 43, and a solder. A resist 44, a third metal film 45, and a through electrode 46 are included.

As best shown in FIG. 8, the second substrate body 38 is an insulating substrate extending in the XY plane. The second substrate main body 38 has a first surface 38 a, a second surface 38 b, and a through portion 51.
The first surface 38a is a surface on the side where the metal case 17 is disposed. The second surface 38b is a surface disposed on the opposite side of the first surface 38a. The second surface 38b is a surface on the side where the second substrate 13 is disposed.
As shown in FIG. 6, the penetrating portion 51 penetrates the second substrate main body 38 facing the hollow portion 33 through the first substrate 16. The penetrating portion 51 is defined by a surface 38c of the second substrate body 38 (a surface on which the third metal film 45 constituting a part of the waveguide is formed). The penetrating portion 51 is rectangular in plan view and extends in the Y direction.

The width W2 of the penetrating part 51 is equal to the width W1 of the hollow part 33. Further, the length L <b> 2 of the penetrating part 51 is equal to the length L <b> 1 of the hollow part 33.
Thus, the length L2 and the width W2 of the penetrating portion 51 are configured to be equal to the length L1 and the width W1 of the hollow portion 33, so that the waveguide is partitioned by the metal case 17 and the third metal film 45. The length and width of the formed portion can be set to predetermined values.

The second metal film 41 is provided around the through portion 51 in the first surface 38 a of the second substrate body 38. A solder 31 is disposed on the upper surface of the second metal film 41. The second metal film 41 is electrically connected to the first metal film 25 via the solder 31. Thereby, the second metal film 41 is electrically connected to the first substrate 16 and the metal case 17.
As the second metal film 41, for example, a metal film similar to the first metal film 25 can be used.

As best shown in FIG. 7, the high-frequency signal pattern 43 is formed on the first surface 38a of the second substrate body 38 located outside the end of the second metal film 41 arranged in the Y direction. Is provided. The pair of high-frequency signal patterns 43 are arranged so as to sandwich the second metal film 41 in the Y direction. Further, the pair of high frequency signal patterns 43 are separated from the second metal film 41 in the Y direction.
The pair of high frequency signal patterns 43 are metal patterns extending in the Y direction. Of the pair of high-frequency signal patterns 43, a high-frequency signal is input to one pattern, and a high-frequency signal that has passed through the filter pattern 23 is output from the other pattern.
The high-frequency signal pattern 43 can be formed using, for example, the same metal film as the metal film constituting the second metal film 41.

The solder resist 44 exposes the upper surface of the second metal film 41 and the upper surface of the high-frequency signal pattern 43, and is formed on the second substrate body 38 on which the second metal film 41 and the high-frequency signal pattern 43 are not formed. It arrange | positions so that the 1st surface 38a may be covered.

As shown in FIG. 6, the third metal film 45 is a film that constitutes a part of the waveguide, and is disposed so as to cover the surface 38 c of the second substrate body 38.
As the third metal film 45, for example, the same type of metal film as the second metal film 41 can be used.
The thickness of the third metal film 45 is very small compared to the width W <b> 2 of the through portion 51.

Referring to FIG. 7, a plurality of through electrodes 46 are provided so as to penetrate the second substrate body 38 located at both ends of the second metal film 41 in the Y direction. One end of each of the plurality of through electrodes 46 is connected to the second metal film 41, and the other end is exposed from the second surface 38 b of the second substrate body 38.
The other ends of the plurality of through electrodes 46 are in electrical contact with the metal substrate 14 by abutting against the substrate mounting surface 14 a of the metal substrate 14.
The second substrate 13 configured as described above is fixed to the metal substrate 14 with screws or the like (not shown).

With reference to FIGS. 1, 2, and 6, the metal substrate 14 includes a substrate mounting surface 14 a and a recess 55. The substrate placement surface 14a is a flat surface, and the second surface 38b constituting the second substrate 13 is placed thereon. The substrate placement surface 14 a is in contact with the other ends of the plurality of through electrodes 46.
Thereby, the metal substrate 14 is electrically connected to the second metal film 41 (in other words, the second substrate 13).

The concave portion 55 is provided in a portion of the metal substrate 14 that faces the through portion 51. For example, the length L3 and the width W3 of the recess 55 may be equal to the length L1 and the width W1 of the hollow portion 33.
Thus, by making the length L3 and width W3 of the recess 55 equal to the length L1 and width W1 of the hollow portion 33, the waveguide constituted by the metal case 17, the third metal film 45, and the recess 55 is provided. The width and length of the tube can be set to predetermined values.

Moreover, the depth D of the recessed part 55 is good to make it equal to the height H1 of the hollow part 33, for example. Thereby, the filter pattern 23 can be disposed at a substantially intermediate position of the waveguide in the Z direction.
The thicknesses of the first substrate 16 and the second substrate 13 are considerably smaller than the height H1 of the hollow portion 33 and the depth D of the recess 55.

In the waveguide filter 10 of the first embodiment, the filter pattern 23 that functions as a filter is provided on the first surface 21a of the first substrate body 21, so that the filter pattern 23 can be accurately formed using a metal film. Therefore, good filter characteristics can be realized in a high frequency region such as a microwave or millimeter wave band.
The first metal film 25 provided on the first substrate body 21 and the first surface 38 a of the second substrate body 38 are electrically connected to the first metal film 25 via the solder 31. By providing the second metal film 41 to be connected to the filter, the filter component 11 can be surface-mounted on the second substrate 13 using a mounting machine (not shown). Good filter characteristics can be realized in the high frequency region.

(Second Embodiment)
FIG. 9 is a perspective view of a waveguide filter according to the second embodiment of the present invention. In FIG. 9, the same components as those shown in FIGS. 1 to 8 are denoted by the same reference numerals.
FIG. 10 is an exploded perspective view of the waveguide filter shown in FIG. 10, the same components as those shown in FIGS. 1 to 9 are denoted by the same reference numerals.
FIG. 11 is a cross-sectional view of the waveguide filter shown in FIG. 9 in the FF line direction. In FIG. 11, the same components as those shown in FIGS. 9 and 10 are denoted by the same reference numerals.

Referring to FIGS. 9 to 11, the waveguide filter 60 of the second embodiment replaces the second substrate 13 constituting the waveguide filter 10 of the first embodiment with a second substrate. 61 is provided and has a surface mount component 63. In other respects, the waveguide filter 60 of the second embodiment is configured similarly to the waveguide filter 10.

The second substrate 61 includes a pair of pads 65 and 66 and a plurality of wiring patterns (not shown) electrically connected separately from them.
Similar to the first embodiment, the second metal film 41 and the high frequency signal pattern 43 are formed on the first surface 38 a of the second substrate body 38. The pair of pads 65 and 66 are provided on the portion where the second metal film 41 and the high-frequency signal pattern 43 are not formed on the first surface 38 a of the second substrate body 38. The pair of pads 65 and 66 can be made of the same metal film as the second metal film 41, for example.
A plurality of wiring patterns (not shown) are provided on the first surface 38 a of the second substrate body 38.

Referring to FIG. 11, the surface mount component 63 includes a first electrode 63A and a second electrode 63B. The first electrode 63A is connected to the pad 65 via the solder 31. The second electrode 63B is connected to the pad 66 through the solder 31.
Thereby, the surface mounted component 63 is surface mounted on the second substrate 61.
Examples of the surface mounting component 63 include a chip resistor and a chip capacitor.

In FIG. 10, only a pair of pads 65 and 66 is shown, but a plurality of pads may be provided. In addition, a semiconductor chip (not shown) may be surface-mounted as a surface-mounted component on a plurality of pads.

According to the waveguide filter 60 of the second embodiment, the filter component 11 is surface-mounted on the second metal film 41 of the second substrate 61, and the surface-mounted component 63 is mounted on the second substrate 61. Since it can be mounted on the pair of pads 65 and 66, the manufacturing process of the waveguide filter 60 can be simplified. Thereby, the manufacturing cost of the waveguide filter 60 can be reduced.
In addition, the waveguide filter 60 of 2nd Embodiment can acquire the effect similar to the waveguide filter 10 of 1st Embodiment demonstrated previously.

As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to the above-described embodiments, and includes designs and the like that do not depart from the gist of the present invention.

(Example)
In the example, electromagnetic analysis in the 28 GHz band was performed by simulation using the waveguide filter 10 shown in FIG. In this electromagnetic analysis, changes in insertion loss (dB) and return loss (dB) in the 28 GHz band were measured. The result is shown in FIG.
FIG. 12 is a graph showing the relationship between frequency, insertion loss, and return loss.
In FIG. 12, the horizontal axis indicates the frequency (GHz) value, and the vertical axis indicates the insertion loss (dB) or return loss (dB) value.

As the second substrate 13, R04350, which is a substrate made by Rogers with a thickness of 0.25 mm, was used. At this time, the length of the second substrate 13 was 60 mm, and the width of the second substrate 13 was 8.6 mm. The width W1 of the hollow portion 33 is 4.3 mm, and the height H1 of the hollow portion 33 is 4.3 mm. The depth of the recess 55 was 4.5 mm, and the width of the recess 55 was 4.5 mm.

Referring to FIG. 12, it was found that the pass band of the filter component 11 is a high frequency band between 27.5 GHz and 29.0 GHz. From this result, it was confirmed that the filter component 11 was able to realize good filter characteristics in the high frequency band of 27.5 GHz to 29.0 GHz.

This application claims priority based on Japanese Patent Application No. 2016-138347 filed in Japan on July 13, 2016, the contents of which are incorporated herein by reference.

The present invention can be applied to a waveguide filter, and according to the present invention, it is possible to provide a waveguide filter having good filter characteristics in a high frequency region.

DESCRIPTION OF SYMBOLS 10,60 Waveguide filter 11 Filter component 13,61 2nd board | substrate 14 Metal substrate 14a Board | substrate mounting surface 16 1st board | substrate 17 Metal case 17A Open end 21 1st board | substrate body 21a, 38a 1st surface 21b , 38b Second surface 23 Filter pattern 24 Microstrip pattern 25 First metal film 25a One surface
27, 46 Through-electrode 31 Solder 33 Hollow part 35 Connection part 38 Second substrate body 38c Surface 41 Second metal film 43 High frequency signal pattern 44 Solder resist 45 Third metal film 51 Through part 55 Recess 63 Surface mount component 63A First electrode 63B Second electrode 65, 66 Pad

Claims (5)

The outer periphery of the first substrate main body, the filter pattern provided on the first surface of the first substrate main body, and the second surface of the first substrate main body located on the opposite side of the first surface The first substrate including the first metal film disposed on the side and the hollow portion extending in one direction is partitioned, the side facing the filter pattern is opened, and the first of the first substrate body is opened. A metal case provided on the surface side of the filter part,
A second substrate body having a penetrating portion in a portion facing the hollow portion via the first substrate; and a first surface of the second substrate body provided around the penetrating portion. A second substrate including a first metal film and a second metal film electrically connected via solder;
A substrate mounting surface on which the second surface of the second substrate body located on the opposite side of the first surface of the second substrate body is placed and electrically connected to the second metal film And a metal substrate having a recess in a portion facing the penetrating portion,
A waveguide filter having: The waveguide filter according to claim 1, wherein a thickness of the first substrate body is smaller than a height of the hollow portion. 3. The waveguide filter according to claim 1, wherein a length of the through portion is equal to a length of the hollow portion, and a width of the through portion is equal to a width of the hollow portion. The length of the concave portion is equal to the length of the hollow portion, the width of the concave portion is equal to the width of the hollow portion, and the depth of the concave portion is equal to the height of the hollow portion. A waveguide filter according to 1. The first surface of the second substrate main body located outside the second metal film is provided with a pad, and has a surface mount component mounted on the pad via the solder. 5. The waveguide filter according to any one of 1 to 4.

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