JP2007274106A - High frequency module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high frequency module capable of attaining high density mounting. <P>SOLUTION: The high frequency module includes: high frequency circuit boards 6, 9 mounted with an amplifier of a transmission system or a reception system; a case 2 containing and mounting the high frequency circuit boards 6, 9 with a prescribed width, and including an inner bottom area with a prescribed length extended along a propagation direction of a radio wave transmitted/received by the amplifier, and inner wall parts respectively raised from both ends of the inner bottom part in the width direction; inner covers (function circuit boards) 10, 11 fixedly supported at the intermediate height of the inner wall parts in the case 2, and the inner covers 10, 11 and the high frequency circuit boards 6, 9 configure a hierarchical board structure. Further, the inner covers 10, 11 have functions of a power supply circuit and a control circuit or the like, have a ground conductor solid pattern 12 on inner layers, a ground pattern 13 connected to the ground conductor solid pattern 12 to front layers, and the ground conductor solid pattern 12 reaches a conductive state to the case 2 via the ground pattern 13. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a high frequency module such as a communication device or a radar device in a microwave band and a millimeter wave band belonging to a high frequency.

  In the conventional receiver, by attaching a metal shield plate above the IF amplifier and the output terminal mounting part of the circuit board, the adverse effect caused by the unstable back cover of the ground is reduced, creating a stable grounding situation. Isolation characteristics are improved by changing the spatial signal reflection state (see, for example, Patent Document 1).

JP 2003-37510 A

  In the receiving apparatus according to the above-mentioned Japanese Patent Laid-Open No. 2003-37510, the metal shield plate is in contact with the chassis on a relatively wide surface, so that the mounting area is reduced by the contact area with the chassis, and high-density mounting is performed. There was a problem of disadvantage.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a high-frequency module capable of high-density mounting.

  A high-frequency module according to the present invention includes a high-frequency circuit board on which a transmitter or receiver amplifier is mounted, the high-frequency circuit board being housed and mounted, and having a predetermined width in a propagation direction of radio waves transmitted and received by the amplifier. A case having an inner bottom portion extending along a predetermined length and inner wall portions rising from both ends in the width direction of the inner bottom portion, an outer cover covering the upper portion of the case, and an intermediate height of the inner wall portion in the case The functional circuit board is fixed and supported, and the functional circuit board and the high-frequency circuit board constitute a hierarchical board structure. The functional circuit board has functions of a power supply / control circuit and the like, and has a ground surface on the entire inner layer. A solid conductor pattern, having a ground pattern connected to the ground conductor solid pattern on the surface layer, and the ground conductor solid pattern and the case via the ground pattern And it serves as a passing state.

  According to the high frequency module of the present invention, since the functional circuit board and the high frequency circuit board have a hierarchical board structure, high-density mounting is possible, and the ground conductor solid pattern on the inner layer of the functional circuit board is used for the cut-off structure. There is an effect that it becomes possible.

Embodiment 1 FIG.
A high-frequency module according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is an exploded plan view of a high-frequency module. The high-frequency module of the present invention is made of a metal that contacts and covers a case 2 that houses and mounts high-frequency circuit boards 6 and 9 and the like, and an upper portion of the case 2 The outer cover 1 and the inner cover (corresponding to a functional circuit board, the details of which will be described later) 10 and 11 are arranged on the high-frequency circuit boards 6 and 9 in the case 2 so as to form a hierarchical board structure. And is mainly composed.

  The case 2 is formed, for example, by machining aluminum, and as shown in the figure, the planar shape is rectangular and the side wall portion has a constant height, and the high-frequency circuit board 6 is formed in the internal space. 9 and the like, and a wall surface that separates the mounting space of the two high-frequency circuit boards 6 and 9 mounted in a parallel state along the long side direction of the case 2 at the central portion inside the case 2 The portion is provided so as to protrude from the bottom surface portion. High-frequency circuit boards 6 and 9 are housed and mounted inside the case 2, have a predetermined width, and have an inner bottom surface having a predetermined length extending along the propagation direction of radio waves transmitted and received by an amplifier (described later). And an inner wall portion that rises from both ends in the width direction of the inner bottom surface portion.

A transmission input / reception output connector 3 is attached to one side wall portion of the case 2 (corresponding to one short side when the planar shape of the case 2 is rectangular), and another side wall portion ( A reception input / transmission output connector 4 is attached to the other short side. The case 2 has a transmission input / reception output connector 3 and a high-frequency transmission line disposed in the case 2 (not shown in FIG. 1 and has the same configuration as the high-frequency transmission line 15 shown in FIG. 3 described later). The transmission / reception changeover switch 5a and the changeover switch mounting board 5 on which the transmission / reception changeover switch 5a is mounted are arranged. A transmission system amplifier 6a is mounted on the inner bottom surface of the case 2 surrounded by the central inner wall portion in the case 2 and one long side wall portion of the case 2 (when the planar shape of the case 2 is regarded as a rectangle). A high-frequency circuit board 6 in which a receiving amplifier 9a is mounted is placed inside the case 2 in which the high-frequency circuit board 6 is housed and mounted and surrounded by the central inner wall of the case 2 and another long side wall of the case 2. Stored and mounted.
A circulator 7 is disposed adjacent to the high-frequency circuit board 6 in the case 2 on the side where the reception input / transmission output connector 4 is attached, and the reception RF relay board 8 is disposed between the circulator 7 and the high-frequency circuit board 9. Be placed.

  An inner cover holding flat portion (function) for holding the inner covers 10 and 11 is provided at an intermediate height of the inner wall portion (including the central inner wall portion) in which the high frequency circuit boards 6 and 9 inside the case 2 are stored and mounted. Corresponding to a circuit board holding plane part.) 2a is provided. 2 is a cross-sectional view taken along the line AA in FIG. 1 (a cross-sectional view along a direction perpendicular to the propagation path of the radio wave passing through the transmission system amplifier 6a and the reception system amplifier 9a. ), The thickness of the inner wall portion of the case 2 at a position below the mounting surface of the inner covers 10 and 11 is the thickness of the inner wall portion of the case 2 at a position higher than the mounting surface of the inner covers 10 and 11. The flat portion of the step caused by the difference in the thickness of the inner wall portion is used as the inner cover holding flat portion 2a, and the inner covers 10 and 11 are set at the intermediate height of the inner wall portion of the case 2. keeping. The inner covers 10 and 11 are functional circuit boards having functions such as a power supply circuit / control circuit for the transmission / reception changeover switch 5, the transmission system amplifier 6, and the reception system amplifier 9. Since the inner covers 10 and 11 and the high-frequency circuit boards 6 and 9 each constitute a hierarchical board structure, a two-story board structure can be realized in a limited mounting area, and high-density mounting is possible. Yes.

  As shown in the sectional view of FIG. 2, the inner cover 10 (11) includes an inner cover upper layer substrate 10a (11a), an inner cover lower layer substrate 10b (11b), an inner cover upper layer substrate 10a (11a), and an inner cover lower layer substrate. 10b (11b), the ground conductor solid pattern 12 formed to spread over the entire surface of the inner cover 10 (11), and the surface layer of the inner cover lower layer wiring 10b (11b) (on the high frequency circuit board 6, 9 side) The ground pattern 13 is provided. The ground conductor solid pattern 12 on the inner layer of the inner cover 10 (11) and the ground pattern 13 provided on the back surface layer are electrically connected by a through hole 13a that is a conductive wiring penetrating the inner cover lower layer wiring 10b (11b). It is in the state (conduction state). The inner covers 10 and 11 can be fixed using, for example, a fixing screw, an adhesive, or welding.

  Next, the flow of radio waves (RF signals) propagating in the high frequency module will be described. Further, in FIG. 1, the propagation path of radio waves is indicated by arrows. First, the transmission RF signal is input from the transmission input / reception output connector 3, the transmission system path is selected by the transmission / reception selector switch 5, amplified by the transmission system amplifier 6, and after passing through the circulator 7, the reception input / transmission output connector 4 is output. On the other hand, the reception RF signal is input from the reception input / transmission output connector 4, passes through the circulator 7 and the reception RF relay substrate 8, is amplified by the reception system amplifier 9, and after selecting the reception system path by the transmission / reception selector switch 5, Output from the transmission input / reception output connector 3.

  As shown in the AA cross-sectional view of FIG. 1, the case 2 constituting the high-frequency module has a structure in which a high-frequency circuit board 6 (9) is disposed therein. In the first embodiment, the case 2 has a predetermined width capable of accommodating the high-frequency circuit board 6 (9) as a space for accommodating and mounting the high-frequency circuit board 6 (9), and the amplifier (6a (9a )) Is a predetermined length of the inner bottom surface extending along the propagation direction of the radio wave transmitted and received, and the inner wall portions rising from both end portions in the width direction of the inner bottom surface portion (corresponding to the central inner wall portion and the long side wall portion described above) It is a structure with. FIG. 2 shows a case where the dimension a corresponding to the distance between the inner wall portions of the two opposing surfaces of the case 2 is the same as the width of the high-frequency circuit board 6 (9). In order to secure the tolerance, the dimension in the width direction of the high-frequency circuit board 6 (9) may be formed smaller than a.

  Next, the cutoff structure of the high frequency module will be described. When the high-frequency module according to the first embodiment is applied to a rectangular waveguide model (when the shape of a cross section perpendicular to the propagation path of a radio wave is a square (a × b, a> b)), a cutoff structure is obtained. In order to obtain, a dimension a (corresponding to a dimension in the propagation path width direction of the radio wave transmitted and received by the amplifier 6 (9)) corresponding to the distance between the inner wall portions of the two opposing surfaces of the case 2 can propagate. It is necessary that the relationship with the frequency f of the radio wave satisfy c / 2a <f <c / a (c: speed of light). The a dimension that satisfies the above relational expression is called a cut-off dimension. The dimension b when applied to the rectangular waveguide model is a solid conductor plane in the inner cover 10 (11) from the surface of the inner bottom surface portion where the high frequency circuit board 6 (9) of the case 2 as shown in FIG. The dimension corresponds to the distance to the bottom surface of the pattern 12 (Note that FIG. 2 includes a portion drawn at a reduced scale so that the cross-sectional structure can be easily understood). Since the relational expression between the dimension a and the frequency is a matter described in a general textbook, the description thereof is omitted.

Specifically, when the frequency f of the radio wave used by the high frequency module according to the present invention is a high frequency belonging to the microwave band or the millimeter wave band, for example, 1.5 GHz (light velocity c≈3.0 × 10 ⁸ m / s), by solving the above relational expression and setting the a dimension so that the relation of 100 mm <a <200 mm is established, a cut-off structure can be obtained. By obtaining the cut-off structure, a structure that does not propagate (blocks) a signal having a wavelength other than the high frequency to be transmitted and received can be obtained.

  Thus, high-density mounting can be achieved by adopting a hierarchical substrate structure of the inner covers 10 and 11 and the high-frequency circuit boards 6 and 9, and the ground conductor solid pattern 12 is formed on the inner layers of the inner covers 10 and 11. By providing the ground conductor solid pattern 12, the inner wall surface of the case 2 (the surface of the inner wall portion serves as a shield wall) and the inner bottom surface portion of the case 2 where the high-frequency circuit boards 6 and 9 are stored and mounted. Therefore, a cut-off structure can be realized, and a structure that does not propagate radio waves that are not transmission / reception objects can be obtained.

Embodiment 2.
Next, a second embodiment of the present invention will be described with reference to FIGS.
In the above-described first embodiment, the case where the inner cover holding flat surface portion 2a is formed on the inner wall portion of the case 2 and the inner covers 10 and 11 are held is shown. However, in the second embodiment, as shown in FIG. Further, a plurality of columnar metal posts 14 are arranged at a position close to the inner wall portion of the case 2 at a portion where the inner cover 10 (11) in the case 2 is arranged, and the inner cover is formed on the upper surface of the metal post 14. 10 and 11 are fixed, and the inner covers 10 and 11 are supported. A high-frequency transmission line in the high-frequency module is denoted by reference numeral 15.

  FIG. 4 shows a cross-sectional view taken along line BB in FIG. The plurality of metal posts 14 are arranged so as to extend in the vertical direction with the bottom surface in contact with the inner bottom surface in the case 2 (the shape of all the metal posts 14 is the same shape, height, etc. The upper surface of the metal post 14 is in contact with the ground pattern 13 constituting the inner cover 10 (11), and the case 2 and the inner cover 10 (11) are in a conductive state via the metal post, so that the GND potential It is kept in. The shape of the high-frequency circuit board 6 (9) is a shape having a cutout portion in which the space for arranging the metal posts 14 is cut out. However, when viewed as the overall shape, the high-frequency circuit board 6 (9) has a predetermined width (compared to the first embodiment). Then, it is different in that the inner cover holding flat surface portion 2a is not formed.) And has a rectangular substrate shape that fits in the inner bottom surface portion of the case 2 having a predetermined length extending along the propagation direction of the radio wave. .

  In the case of the high-frequency module according to the second embodiment, the metal post 4 is a conductive material and constitutes a part of the shield wall. Therefore, as shown in FIG. The dimension a is determined by the narrowest width, that is, the distance between the two metal posts 14 arranged close to the inner wall of the opposite case 2. By arranging the metal post 14 so that the dimension a satisfies the relational expression shown in the first embodiment, the ground conductor solid pattern 12, the metal post 14, the inner wall portion of the case 2 and the inner bottom surface portion A cut-off structure can be obtained also in the high-frequency module of the second embodiment.

  Further, FIG. 5 shows a cross-sectional structure different from FIG. In FIG. 4, the height of the metal post 14 from the inner bottom surface portion of the case 2 (the same as the bottom surfaces of the high-frequency circuit boards 6 and 9) to the bottom surfaces of the inner covers 10 and 11 (the back surface side surface of the ground pattern 13). In FIG. 5, the high-frequency circuit boards 6 and 9 having a certain width are arranged on the inner bottom surface of the case 2, and the metal posts 14 are arranged on the high-frequency circuit boards 6 and 9. Indicates the case. In the case of FIG. 5, for example, the metal post 14 has a screw shape at the bottom, and can be configured to serve as a fixing screw for the high-frequency circuit boards 6 and 9 (see FIG. 5). (The description of the bottom screw shape of the metal post 14 is omitted.) Even in the case of FIG. 5, the dimension “a” when applied to the rectangular waveguide model corresponds to the distance between the metal posts 14.

Embodiment 3.
Next, a high frequency module according to Embodiment 3 of the present invention will be described. In the second embodiment described above, the state in which the inner covers 10 and 11 are in close contact with the inner wall portion in the case 2 is illustrated in the cross-sectional views of FIGS. 4 and 5. However, when a product is actually manufactured, the substrate (inner covers 10 and 11) having a size smaller than the space in the case 2 may be manufactured in consideration of the tolerance at the time of mounting. In that case, when the inner covers 10 and 11 are placed and fixed on the metal post 14, the inner wall surface of the case 2 and the inner covers 10 and 11 are not in close contact with each other, and a gap portion is generated. In the high frequency module according to the third embodiment, the metal tape 16 shown in the exploded plan view of FIG. 6 is shown in FIG. 7 in such a manner as to close the gap formed between the inner wall surface of the case 2 and the inner covers 10 and 11. As shown in the CC sectional view of FIG.

  The metal tape 16 is a strip-shaped tape having a certain width, and is bent at an angle of 90 degrees along the length direction so as to be, for example, a half width (the back surface side serving as the bonding surface of the metal tape 16 is 270 degrees) It will be bent at an angle of.) The portion where the metal tape 16 is bent can be changed by adjusting the width of the gap by a module adapted for this structure. The bonding surface of the metal tape 16 is in a state of being bonded to the inner wall of the case 2 and the upper surfaces of the inner covers 10 and 11, but the width and bending location of the metal tape 16 are determined so as to ensure a bonding surface having a certain area or more. .

By attaching the metal tape 16 so as to close the gap between the inner covers 10 and 11 and the inner wall portion of the case 2 in the case 2, the shielding property of the high-frequency circuit board, that is, the spatial isolation is improved. Is possible.
Needless to say, by realizing the structure shown in FIGS. 6 and 7, high-density mounting and a cut-off structure can be realized as in the case of the first and second embodiments.

1 is an exploded plan view of a high frequency module according to Embodiment 1 of the present invention. It is sectional drawing which follows the AA line of FIG. It is a disassembled top view of the high frequency module by Embodiment 2 of this invention. It is sectional drawing which follows the BB line of FIG. FIG. 4 is another cross-sectional view taken along line BB in FIG. 3. It is a disassembled top view of the high frequency module by Embodiment 3 of this invention. It is sectional drawing which follows the CC line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer cover 2 Case 2a Inner cover holding plane part 3 Transmission input / reception output connector 4 Reception input / transmission output connector 5 Substrate mounting board 5a Transmission / reception selector switch 6, 9 High frequency circuit board 6a Transmission system amplifier 7 Circulator 8 Reception RF relay Board 10, 11 Inner cover (functional circuit board)
12 Ground conductor solid pattern 13 Ground pattern 13a Through hole 14 Metal post 15 High frequency transmission line 16 Metal tape.

Claims (4)

  A high-frequency circuit board on which a transmitter or receiver amplifier is mounted, the high-frequency circuit board being housed and mounted, having a predetermined width, and a predetermined length extending along a propagation direction of a radio wave transmitted and received by the amplifier A case having an inner bottom surface and inner wall portions rising from both ends in the width direction of the inner bottom surface portion, an outer cover covering the upper portion of the case, and a functional circuit board fixedly supported at the intermediate wall inner height in the case The functional circuit board and the high-frequency circuit board constitute a hierarchical board structure, and the functional circuit board has functions such as a power supply / control circuit, a ground conductor solid pattern on the inner layer, and the ground conductor on the surface layer. A high frequency module having a ground pattern connected to a solid pattern, wherein the ground conductor solid pattern and the case are in a conductive state via the ground pattern. Lumpur.   The functional circuit board is placed and fixed on a functional circuit board holding flat part provided at an intermediate height of the wall surface part of the case, and the ground conductor solid pattern in the functional circuit board and the inner wall part of the case The high-frequency module according to claim 1, wherein a cut-off structure is configured by the inner bottom surface portion.   A plurality of metal posts disposed inside the case, the functional circuit board is placed and fixed on the metal post, and the ground pattern is in conduction with the case via the metal post; 2. The high-frequency module according to claim 1, wherein a cut-off structure is constituted by the ground conductor solid pattern in the functional circuit board, the metal post, the inner wall portion and the inner bottom surface portion of the case.   4. The high frequency module according to claim 2, wherein when there is a gap between the functional circuit board and the inner wall of the case, a metal tape is attached to close the gap. .

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