JP5279424B2 - High frequency transmission equipment - Google Patents

Description

  The present invention relates to a high-frequency transmission device, and more particularly, to a structure of a high-frequency transmission device for transmitting a high-frequency signal in a configuration in which various high-frequency module substrates used for high-frequency signal processing from a microwave band to a millimeter wave band are attached to a mounting substrate. .

  Conventionally, in a high-frequency transmission apparatus that handles signals from the microwave band to the millimeter wave band, a circuit board on which various high-frequency modules (devices) are mounted is mounted on another mounting circuit board, It is transmitted between the module and the mounting circuit board.

  FIG. 10 shows one configuration example of a conventional transmission apparatus. The module has a shield housing 22 having a cavity 21, a transmission line 23 formed on the front surface (upper surface), and the transmission line on the rear surface. 23 includes a module substrate 27 on which a connection electrode 25 and a ground pattern (ground electrode) 26 connected to each other through a through hole 24 are formed, and a transmission line 29 and a ground pattern 30 are formed on the mounting portion on the surface. In addition, a mounting substrate 33 on which a ground pattern 32 to which the ground pattern 30 is connected via a through hole 31 is formed on the back surface, and a metal casing 34 on the back surface side of the mounting substrate 33 is provided. Then, the module substrate 27 and the mounting substrate 33 are bonded with the solder 35 or the like so that the ground pattern 26 and the ground pattern 30 of the module and the mounting portion are connected, and the connection electrode 25 and the transmission line of the transmission line 23 are connected. 29 is connected. Reference numeral 36 denotes a ground pattern on the upper surface of the module substrate 27.

FIG. 11 shows another configuration example of the conventional transmission apparatus (example using a tab lead). In this case, a tab lead 38 is provided on the back surface of the module substrate 27, and the tab lead 38 and the transmission line 29 are provided. The tab lead 38 and the through hole 31 are connected by solder 35.
In such a transmission apparatus, the dimensions are optimized or an impedance correction circuit is added so that mismatching does not occur in the entire connection portion.
JP 2004-214584 A

  However, in the conventional high-frequency transmission device, when the frequency to be handled increases and the substrates (27, 33) to be used become thin, the width of the electrodes for connecting the transmission lines 23, 29 of the module substrate 27 and the mounting substrate 33 to each other. There is a problem that it becomes thin and it becomes difficult to align the connection electrodes.

  For example, in the case of a package incorporating a device such as FET, MMIC, etc., even with the structure shown in FIG. 10, high precision and stable mounting is possible by solder reflow mounting. However, when it is configured as a high-frequency module including a plurality of circuits inside, mounting by solder reflow is often difficult, and generally a method of connecting via an expensive high-frequency connector or coaxial cable is adopted. ing.

  Also, there is a method in which the module itself is fixed with screws, and only the electrode connection portion is connected by spot soldering using a soldering iron or laser, but even in this case, a tab lead (metal plate) or through hole as shown in FIG. Mounting is difficult unless the soldering electrode cut in half is used to directly apply heat to the joint to form a solder fillet.

  In addition, one of the purposes of modularizing high-frequency circuits is to share a circuit with a wide frequency characteristic so that a narrow-band circuit part including an oscillator can be replaced as a modular circuit. However, even in such a case, the connection between the module and the mounting part is often made with an expensive high-frequency connector or coaxial cable.

The present invention has been made in view of the above problems, and its purpose is to facilitate the alignment of connection electrodes of transmission lines when connecting various high-frequency module substrates to a mounted high-frequency circuit substrate, and soldering. Another object of the present invention is to provide a high-frequency transmission device that can perform stable transmission by connecting transmission lines of each substrate without using expensive connectors or the like.

To achieve the above object, the invention according to a first aspect of the invention, the high frequency transmission apparatus for stacked multiple substrates high-frequency transmission line and the ground electrode are formed, on the front surface, an empty area of the ground electrode is formed, and the open-end pattern of the transmission line to an empty area is formed on the back surface, a high frequency module board empty area of the ground electrode at a position substantially coincident with the said surface sky area is formed, on the front surface A mounting high-frequency circuit board in which an empty area of the ground electrode is formed, and an open end pattern of the transmission line is formed in the empty area, and a ground electrode is formed on the back surface, and a back-surface ground electrode of the high-frequency module board by superimposing the mounting high-frequency circuit is connected to the surface ground electrode of the substrate, and a mounting high-frequency circuit board with the RF module substrate directly in a state to match the respective empty area and A series resonant circuit formed with a capacitive coupling portion that capacitively couples the open-circuit patterns of the respective transmission lines while being DC-insulated, and an impedance matching unit provided in the series resonant circuit, the series resonance A high frequency is transmitted by a circuit.
According to a second aspect of the invention, said as a capacitive coupling portion, on the back surface of the mounting a high-frequency circuit board, provided with a free area of the ground electrode at a position substantially coincident with the surface thereof free space, the rear surface side of the mounting high-frequency circuit board The metal casing disposed in the upper surface is provided with a digging hole having substantially the same area as the back surface empty area, and the back surface empty area of the high-frequency module substrate has a thickness equal to or greater than the thickness of the ground electrode on the back surface. A dielectric sheet having a thickness is provided.

The invention according to claim 3 is characterized in that a cavity having substantially the same area as that of the surface empty region is provided in the shield casing disposed on the surface side of the high-frequency module substrate.

According to the configuration of the present invention, the respective ground electrodes are directly connected between the high- frequency module substrate and the mounted high-frequency circuit substrate, and for each transmission line, the coupling capacitance between the open end patterns, the transmission line, and the open end A series resonance circuit is formed by the impedance matching portion between the patterns, and high- frequency transmission is performed between the transmission lines arranged on the high- frequency module substrate and the mounting high-frequency circuit substrate by the series resonance circuit.

  According to the high-frequency transmission device of the present invention, since the transmission lines are connected by capacitive coupling, it is easy to align the connection electrodes of the transmission lines of a plurality of substrates, and without using soldering or expensive connectors. In addition, there is an effect that transmission lines of a plurality of substrates can be connected to each other to perform stable transmission, and the connection can be facilitated and the cost can be reduced.

According to the invention of claim 2, since the digging hole is provided in the metal casing disposed on the back surface side of the mounting high-frequency circuit board, the deterioration of the characteristics due to the ground capacity of the open-ended pattern is prevented, and the broadband transmission characteristics are obtained. The effect is obtained.
Further, the free area of the capacitive coupling portion to which a ground pattern in the back surface of the RF module substrate is not formed, is provided with the dielectric sheet, the gap that exists between the high frequency module board and the mounting a high-frequency circuit board in the capacitive coupling portion As a result, it is possible to improve the deterioration of the transmission characteristics due to.

  1 to 4 show a configuration of a high-frequency transmission device according to an embodiment of the present invention. FIG. 1 is a perspective view of an upper shield housing, and FIGS. 2 and 3 are exploded views. FIG. 4 is a sectional view. As shown in each figure, the transmission device of the embodiment connects various modules to the mounting part, and the module is formed on a metal shield housing 2 having a coupling part cavity 1 on the surface (upper surface). The transmission line 3 has a module substrate 7 on which a tip opening pattern 3a and a ground pattern (ground electrode) 4 are formed, and a ground pattern 5 is formed on the back surface (lower surface). A mounting substrate 13 having a tip opening pattern 9a and a grounding pattern 10 formed thereon, and a grounding pattern 12 to which the grounding pattern 10 is connected via a through hole 11 on the back surface, and a metal casing 14. Yes.

  The transmission lines 3 and 9 of the module substrate 7 and the mounting substrate 13 are configured by a transmission line pattern such as a microstrip line or a grounded coplanar waveguide. Further, in the module substrate 7, the ground pattern 4 on the upper surface is provided so as to surround the high-frequency circuit unit, and the ground pattern empty region for configuring the capacitive coupling unit in which the open end pattern 3 a of the transmission line 3 is arranged. (In other words, a rectangular missing portion where no ground pattern surrounding the tip opening pattern 3a is provided) 4C is left, and the ground pattern 5 on the back surface is also formed with an empty region for forming a capacitive coupling portion (the above-mentioned 4C and (A substantially matching region) 5C is formed leaving. The shield housing 2 has a shape that covers the high-frequency circuit unit, is disposed so as to be in electrical contact with the ground pattern 4 on the upper surface of the module substrate 7, and serves to electrically shield and protect the high-frequency circuit. To do.

  In the mounting substrate 13, the open end pattern 9 a of the transmission line 9 on the upper surface is formed at a position facing the open end pattern 3 a of the module substrate 7 with the substrate base material interposed therebetween, and the ground pattern 10 is An empty region 10C that is substantially the same as the empty region 4C and 5C is left, and the ground pattern 12 on the back surface is substantially the same size as the empty region 10C and is used to form a capacitive coupling portion ( (A region substantially coincident with the above 4C) is formed leaving 12C.

  Further, the metal casing 14 on the lower side of the mounting substrate 13 is provided with a digging hole 14D having substantially the same area as the empty area 12C. The digging hole 14D cooperates with the empty area 10C. Thus, it serves to prevent the deterioration of the characteristics due to the ground capacitance of the open end patterns 3a, 9a.

  Further, in the embodiment, the ground pattern empty region 5C on the back surface of the module substrate 7 has a shape slightly smaller than the empty region 5C so as not to overlap the ground pattern 5, and is equal to or more than the thickness of the ground pattern 5. A dielectric sheet 16 having a thickness of 1 mm is provided. The dielectric sheet 16 can be formed by using, for example, a solder resist or the like, and serves to improve the deterioration of the transmission characteristics caused by the gaps existing in the empty area 5C.

  As shown in each figure, the module substrate 7 and the mounting substrate 13 having such a configuration are such that the open end patterns 3a and 9a face each other with the module substrate 7 and the dielectric sheet 16 interposed therebetween, and the empty regions 4C, 5C, and 10C. 12C and the digging portion 14D are arranged in the vertical direction, and the members 2, 7, 13, and 14 are arranged to overlap each other, and between the lower surface of the shield housing 2 and the ground pattern 4 on the upper surface of the module substrate 7. Between the ground pattern 5 on the back surface of the module substrate 7 and the ground pattern 10 on the top surface of the mounting substrate 13, and between the ground pattern 12 on the back surface of the mounting substrate 13 and the metal housing 14, mechanical contact or solder or It is electrically connected by a conductive adhesive or the like. Accordingly, the transmission lines 3 and 9 are connected by capacitive coupling in a state where they are insulated in a direct current manner, with the open end patterns 3a and 9a overlapping with the module substrate 7 and the dielectric sheet 16 interposed therebetween.

  Further, matching elements (matching elements) MP1 and MP2 having a configuration in which the line width is changed (reduced) between the transmission line 3 and the open end pattern 3a and between the transmission line 9 and the open end pattern 9a. Is provided.

  The embodiment has the above-described configuration. In the high-frequency transmission device according to the embodiment, the gap between the open end pattern 3a of the transmission line 3 on the upper surface of the module substrate 7 and the open end pattern 9a of the transmission line 9 on the upper surface of the mounting substrate 13 is. A series resonance circuit is formed by the capacitance component, the inductance components of the patterns 3a and 9a, and the matching elements MP1 and MP2, and a signal is transmitted by the series resonance circuit.

  FIG. 5 shows an equivalent circuit of the transmission apparatus according to the embodiment. In FIG. 5, C1 and C2 are ground capacities of the open end pattern 3a on the upper surface of the module substrate 7, and C3 and C4 are open end patterns. Capacitance components 3a and 9a, C5 and C6 are ground capacities of the open end pattern 9a on the top surface of the mounting substrate 13, L1 and L2 are inductive (inductance) components of the open end patterns 3a and 9a, and MP1 is a module. A matching element between the open end pattern 3 a on the upper surface of the substrate 7 and the transmission line 3, that is, a portion with a reduced width, MP2 represents a matching element between the open end pattern 9 a on the upper surface of the mounting substrate 13 and the transmission line 9.

  As can be seen from the equivalent circuit of FIG. 5, the capacitances C3 and C4 between the open end patterns 3a and 9a facing the upper surface of the module substrate 7 and the upper surface of the mounting substrate 13 and the inductive components L1 and L2 of the patterns 3a and 9a A series resonant circuit is configured. In this series resonance circuit, when there is no influence of other parasitic components, if the resonance frequency is a desired frequency to be transmitted, transmission is possible with low loss, but in practice, as in C1, C2, C5, and C6. Although not described in this equivalent circuit and the equivalent circuit, other parasitic components due to the layout exist and are affected. In addition, the coupling portion resonance frequency of the open end pattern may not be adjusted to a desired frequency due to a demand for miniaturization or the like. Therefore, in the embodiment, as described above, the matching elements MP1 and MP2 are provided, and the grounding is achieved by optimizing the resonance frequency and impedance matching by the open end pattern coupling portion and the matching elements MP1 and MP2. It is possible to eliminate the influence of capacitance and parasitic components.

  However, in general, when the parasitic component is large, the band is very narrow as a result of the impedance matching described above, and a desired band cannot actually be obtained and often cannot be used. Therefore, in the embodiment, a ground pattern empty region 12C is provided in the ground pattern 12 (capacitive coupling portion thereof) on the opposite surface (back surface) of the open end pattern 9a of the mounting substrate 13, and the metal casing 14 below the ground pattern 12 is provided. By providing the digging hole 14D on the upper surface, the influence of the grounding capacitors C5 and C6 is reduced.

  Further, even when the width of the open end pattern 9a is widened by the vacant region 12C and the dug hole 14D, characteristic deterioration on the high frequency side due to the grounding capacitors C5 and C6 can be prevented, and the mounting substrate 13 can be made thick. Since the coupling capacitances C3 and C4 can be increased, wideband transmission characteristics can be obtained. Further, such a configuration has an advantage that even when there is a positional deviation in the mounting of the module substrate 7 and the mounting substrate 13, the change in the coupling capacitance is small and the deterioration of the transmission characteristics is also small.

  6A and 6B show a configuration when the module is attached to the mounting portion, and FIG. 6A shows the ground pattern portions (4, 5, 10 of the module M and the mounting portion S). 12), screws 16 are arranged and fixed, and the ground patterns 4, 5, 10, 12 and the like are connected by mechanical contact. FIG. 6B shows the ground pattern portion connected by solder 35 or a conductive adhesive. Even with such a mounting structure, in the present invention, fluctuations in characteristics due to variations in mounting positions can be suppressed, and various modules M can be easily replaced without using a high-frequency connector or the like.

  FIG. 7 shows the transmission characteristics according to the configuration of the example. The insertion loss is 101 and the reflection loss is 201. Both the insertion loss and the reflection loss are good characteristics. Since the transmission device of the present invention is not a waveguide mode transmission, the width of the ground pattern empty regions 4C, 5C, 10C, and 12C around the capacitive coupling portion and the shield casing 2 or the metal casing 14 are dug. Even if the width of the insertion hole 14D is a dimension that is equal to or less than the cutoff as the waveguide at the frequency of the use band, it can be used although the band is narrowed.

  The overlapping length of the open top pattern 3a on the top surface of the module substrate 7 and the open top pattern 7a on the top surface of the mounting substrate 13 is the widest band when the wavelength is about 1/4 wavelength. It can be used at a desired frequency by correcting the inductive components of the open patterns 3a and 7a and the matching elements MP1 and MP2 before and after. Again, this is a trade-off between miniaturization and bandwidth.

  Furthermore, in the embodiment, by forming a dielectric sheet 16 that is the same as or slightly thicker than the thickness of the ground pattern 5 in the blank area 5C of the ground pattern 5 on the back surface of the open end pattern 3a of the module substrate 7, It is possible to improve the deterioration of transmission characteristics caused by the 5C gap. That is, since the ground pattern 5 made of copper foil of the module substrate 7 usually has a thickness of about 30 μm, when the conductor sheet 16 is not provided, when the module substrate 7 is attached to the mounting substrate 13, A gap due to the thickness of the grounding pattern 5 exists between the tip opening pattern 9 a on the upper surface of the mounting substrate 13 and the base material of the module substrate 7. Here, in the capacity component between the tip open patterns 3a and 9a, it may be considered that the thickness of the base material of the module substrate 7 is constant. However, when the gap is present, Since the capacitance component formed by the serial air layer (dielectric constant 1) is small and the combined capacitance is small, the transmission characteristics are deteriorated.

  FIG. 8 shows transmission characteristics when the dielectric sheet 16 is used and when the dielectric sheet 16 is not used. When the dielectric sheet 16 is not provided and a gap of 30 μm exists, a dotted insertion loss 102, The characteristic of the reflection loss 202 is obtained. That is, when there is a gap, the capacitance component becomes small, the resonance frequency moves to the high frequency side, and the matching state also changes, so that the transmission characteristics deteriorate. On the other hand, when the dielectric sheet 16 is provided, since the combined capacity is larger than the gap, the characteristics of the solid line insertion loss 101 and the reflection loss 201 are obtained and stable as shown in FIG. Transmission characteristics can be obtained. Although the gap width of the empty area 5C may change due to the change in the ambient temperature, in the embodiment, the thickness of the dielectric sheet 16 is slightly larger than the thickness of the ground pattern 5, that is, the gap width of the empty area 5C. Thus, even when a slight gap is formed due to a change in the ambient temperature, it is possible to prevent the characteristics from fluctuating.

  FIG. 9 shows the configuration of the transmission apparatus when the module substrate is a multilayer substrate. As shown in FIG. 9, the module substrate 7 has an upper substrate 7A and a lower substrate 7B. An inner layer pattern 17 is formed between 7A and the lower substrate 7B. Then, the transmission line 3 and the open end pattern 3a are formed on the upper surface of the upper substrate 7A, and the ground pattern 5 is formed on the back surface of the lower substrate 7B. Other configurations are the same as those in the above embodiment. ing. Even with such a configuration, the same effect as in the above embodiment can be obtained.

  The present invention can be applied to microwave to millimeter wave band high-frequency modules, and can also be applied to packages such as MMIC.

It is a perspective view which shows the structure of the high frequency transmission apparatus which concerns on the Example of this invention. It is the disassembled perspective view which looked at each member of the high frequency transmission device of an example from the upper direction. It is the disassembled perspective view which looked at each member of the high frequency transmission apparatus of an example from the lower diagonal direction. It is sectional drawing which shows the structure of the high frequency transmission apparatus of an Example. It is a figure which shows the simple equivalent circuit of the coupling | bond part of the high frequency transmission apparatus of an Example. It is a perspective view which shows the assembly of the high frequency transmission apparatus of an Example, and the state of attachment. It is a graph which shows the transmission characteristic of an Example. It is a graph which shows the transmission characteristic when not using with the dielectric material sheet in an Example. It is sectional drawing which shows the structure at the time of using the high frequency module which consists of a multilayer board | substrate in an Example. One structural example of the conventional high-frequency transmission apparatus is shown, FIG. (A) is a top view and FIG. (B) is a sectional view. The other example of a structure of the conventional high frequency transmission apparatus is shown, A figure (A) is a top view, A figure (B) is sectional drawing.

Explanation of symbols

2, 22 ... shield housing, 3, 9, 19, 23, 29 ... transmission line,
3a, 9a, 19a, 19b, 19c ... tip open pattern,
4, 5, 10, 12, 20a to 20e, 30, 32, 36... Ground pattern (ground electrode),
4C, 5C, 10C, 12C ... ground pattern empty area,
7, 27 ... module substrate, 13, 33 ... mounting substrate,
14, 34 ... metal casing, 14D ... digging hole,
16 ... dielectric sheet.

Claims (3)

In a high- frequency transmission device in which a plurality of substrates on which high-frequency transmission lines and ground electrodes are formed are stacked ,
On the front surface, the free area of the ground electrode is formed, and open-end pattern of the transmission line is formed in the empty area, on the back, empty area of the ground electrode at a position substantially coincident with the said surface Sky region formed A high-frequency module substrate,
On the front surface, the free area of the ground electrode is formed and the open-end pattern of the transmission line to an empty area is formed on the back surface, and mounting a high-frequency circuit board which the earth electrode is formed,
By superimposing the high-frequency module connecting a back surface ground electrode and the surface ground electrode of the mounting high-frequency circuit board of the board, and the mounting high-frequency circuit board with the RF module substrate directly in a state to match the respective empty regions, each transmission A series resonant circuit in which a capacitive coupling unit that capacitively couples the open end pattern of the line with DC insulation is formed;
Including an impedance matching unit provided in the series resonant circuit,
A high-frequency transmission device that transmits high frequency by the series resonance circuit. As the capacitive coupling part, on the back surface of the mounting a high-frequency circuit board, provided with a free area of the ground electrode at a position substantially coincident with the surface thereof free area, the metal casing that is disposed on the back side of the mounting high-frequency circuit board Is provided with a digging hole of substantially the same area as the backside empty area,
2. The high- frequency transmission device according to claim 1, wherein a dielectric sheet having a thickness equal to or greater than the thickness of the ground electrode on the back surface is provided in an empty area on the back surface of the high-frequency module substrate. 3. The high-frequency transmission device according to claim 2, wherein a cavity having substantially the same area as that of the surface empty region is provided in the shield casing disposed on the surface side of the high-frequency module substrate.

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