JP2012195329A - High frequency module and shield cover for high frequency module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high frequency module in which the unnecessary resonance generated in a shielded internal space by a standing wave is suppressed, excellent electric performance is secured, and reduction in size is achieved.SOLUTION: At a position as the short-circuit end of the standing wave in a closed space inside the module, a multilayer substrate shield cover is configured which has a slit in a back conductor pattern, an inner layer resistance is provided in the slit, a λ/4 waveguide in which the short circuit end is configured by a front/rear conductor pattern and a through via is formed on the shield cover, and the end of the λ/4 waveguide is connected to the inner layer resistance.

Description

  The present invention relates to a high frequency module for processing a high frequency signal in a microwave band or a millimeter wave band, and a shield cover for the high frequency module.

  In the high frequency module, unnecessary electromagnetic waves leak in space from an amplifier, a connection portion with an RF (Radio Frequency) signal transmission substrate connected to the amplifier, a microstrip line, or the like. Due to this unnecessary electromagnetic wave, a standing wave is generated inside the high-frequency module and resonance occurs. For this reason, it is necessary to remove the influence of resonance so that unnecessary electromagnetic waves are not coupled to the amplifier itself or a circuit disposed adjacent thereto, thereby causing malfunction or performance degradation.

  Conventionally, as a method of removing the influence of such resonance, for example, as shown in Patent Document 1, a cutoff block is provided inside a high-frequency module, the cutoff frequency in a closed space is increased, and the resonance frequency is used in a use band. It is known what to remove from.

JP 2009-170843 A

  However, in the above-described conventional high-frequency module, when there are many device parts such as amplifiers, the cut-off block increases with the accommodation area. Therefore, the module increases with the increase in the ground area of the cut-off block and the number of fixing screws. There was a problem that the size became large.

  Further, when the size of a device component such as an amplifier is large, the internal space size of the cut-off block is increased accordingly, and there is a problem that the cut-off frequency cannot be increased.

  The present invention has been made to solve the above-described problems, and an object thereof is to suppress unnecessary resonance due to standing waves generated in a shielded internal space of a high-frequency module and to reduce the size.

  A high frequency module according to the present invention includes a dielectric substrate having a plurality of via holes arranged thereon, a ground conductor formed on the front and back surfaces of the dielectric substrate and connected to the via holes, and a ground conductor on the back surface of the dielectric substrate. A dielectric opening formed on the dielectric opening, a dielectric waveguide having one end connected to the dielectric opening and the other end being a short end of a portion of the via-hole arrangement, and a resistor provided in the dielectric opening And a package that forms a space for housing the high-frequency semiconductor by mounting the high-frequency semiconductor thereon and bonding the back surface of the shield cover through the conductive connection portion. , With.

  The shield cover for a high-frequency module according to the present invention is formed on a dielectric substrate on which a plurality of via holes are arranged, a surface of the dielectric substrate, and a back surface bonded to an external package on which the high-frequency semiconductor is placed. A grounding conductor connected to the via hole, a dielectric opening provided in the grounding conductor on the back surface of the dielectric substrate, and one end connected to the dielectric opening and the other end shorting a part of the via hole arrangement. A dielectric waveguide serving as an end and a resistor provided in the dielectric opening are provided.

  According to the present invention, unnecessary resonance due to standing waves generated in an electromagnetically shielded internal space can be suppressed, good electrical performance can be ensured, and the high-frequency module can be miniaturized.

1 is a cross-sectional view illustrating a configuration of a high frequency module according to Embodiment 1. FIG. It is the figure which looked at the multilayer substrate shield cover for high frequency modules by Embodiment 1 from the back.

Embodiment 1 FIG.
1 is a cross-sectional view showing a configuration of a high-frequency module according to Embodiment 1 of the present invention. FIG. 2 is a view of the multilayer substrate shield cover for the high-frequency module according to the first embodiment as viewed from the back side.

  In the figure, the high-frequency module 100 according to the first embodiment includes a device component 1, a metal block 2, a package 4, a multilayer board shield cover 3, and a chassis 5. The device component 1 is placed on the metal block 2 via a heat dissipation sheet, a heat conductive adhesive, or the like, and fixed by screw fastening. The package 4 and the metal block 2 are placed on the chassis 5 and fixed by screw fastening or an adhesive. In the package 4, a cavity (cavity) surrounded by a wall is formed through the central portion, and the metal block 2 is accommodated in the cavity. The multilayer substrate shield cover 3 is bonded to the upper surface of the wall of the package 4 through metal bumps 20 that are conductive connection portions.

  The device component 1 is composed of a semiconductor element that constitutes an amplifier, a mixer, and the like, and performs signal processing such as signal amplification and frequency conversion on an RF signal in a microwave band or a millimeter wave band. For example, the device component 1 hermetically seals a package in which an MMIC (monolithic microwave integrated circuit) or MIC (microwave integrated circuit) made of a semiconductor element is mounted, and joins a metal carrier having a screw hole on the bottom surface. Composed. The device component 1 is provided with an external terminal 29 for inputting / outputting an RF signal to / from a semiconductor element accommodated therein. The metal block 2 is made of a thermally conductive material having high thermal conductivity, and is made of, for example, an alloy containing tungsten or copper, a carbon-based composite material, or the like. The chassis 5 is made of an alloy such as iron nickel cobalt alloy or tungsten.

  The package 4 is composed of a multilayer substrate in which a plurality of dielectric layers and conductor layers are stacked, and constitutes a parent substrate. Ground patterns (ground conductors) 21 and 22 are formed on the front and back (upper and lower layers) of the package 4. A signal pattern (conductor line) 24 forming a microstrip line is formed on the surface layer (upper layer) of the package 4. The signal pattern 24 is connected to an inner layer signal pattern (conductor line) 25 through a signal via (through VIA) 26. The ground patterns 21 and 22 and the inner layer ground pattern 27 are connected to a plurality of inner layer ground vias (through vias) 23. The plurality of ground vias 23 are arranged at predetermined intervals in the inner layer of the package 4 so as to block electromagnetic waves having an integral multiple of the wavelength λ or λ / 2 from passing through the side surface of the package 4 and entering / exiting the outside. Are arranged in Here, λ is a wavelength that propagates through the dielectric body constituting the package 4 in the use band of the RF signal processed by the device component 1. The external terminal 29 of the device component 1 is connected to the signal pattern 24 on the upper surface of the package 4 via a conductive wire 31 such as a conductor wire (conductive wire) made of gold or silver or a conductor ribbon.

  The multilayer substrate shield cover 3 is composed of a multilayer substrate in which a plurality of single-layer or multilayer dielectrics 10 and conductor layers (ground patterns 11, 12, 18) are laminated, and an upper lid that electromagnetically shields the upper portion of the package 4. Constitute. The multilayer substrate shield cover 3 has a ground pattern 11 formed on the front surface (upper surface), and a ground pattern 12 formed from the middle bottom surface (surface layer) on the back surface (lower surface) side to the inner layer of the side wall 50. Further, the multilayer substrate shield cover 3 is provided with a side wall 50 protruding toward the lower side (package 4 side) so as to surround the bottom of the back surface side. The multilayer substrate shield cover 3 has a ground pattern 18 formed on the lowermost surface of the side wall 50. The ground patterns 11 and 12 are connected by a plurality of ground vias (through vias) 14 and 15. The ground patterns 12 and 18 are connected by a plurality of ground vias (through vias) 19.

The plurality of ground vias 19 are arranged along the inner surface of the side wall 50 at intervals of λ / 8 or less, and are configured to block the passage of electromagnetic waves having an integral multiple of the wavelength λ or λ / 2. Here, λ is a wavelength propagating in the dielectric 10 in the use band of the RF signal processed by the device component 1. Similarly, the plurality of ground vias 15 are arranged along the inner surface of the side wall 50 at intervals of λ / 8 or less, and electromagnetic waves having an integral multiple of the wavelength λ or λ / 2 propagating in the dielectric 10 are also provided. It is configured to block passage. In the illustrated example, the ground via 15 is linearly connected to the ground via 19.
Of course, the side surface of the multilayer substrate shield cover 3 may be covered with a ground pattern so as to block electromagnetic waves that pass through the side surface of the multilayer substrate shield cover 3 and enter and exit the inside and outside.

  As described above, the entire upper surface of the multilayer board shield cover 3 is covered with the ground pattern 11 and the ground vias 15 and 19 are arranged along the outer periphery of the side surface. An electromagnetic shield is provided so as to block the passage of electromagnetic waves to the outside.

The ground pattern 12 is formed with a rectangular slit 13 extending along the side wall 50 and having a conductor penetrated (dielectric surface exposed). Two slits 13 are arranged adjacent to the facing side wall 50, and both form a dielectric window through which electromagnetic waves pass. In addition, a resistance pattern 17 made of a resistor is printed and applied in a rectangular shape on the formation region of the slit 13 in the bottom surface of the multilayer substrate shield cover 3 so as to close the opening of the slit 13.
The number of slits 13 is not limited to two, but may be one or three or more.

  As shown in FIGS. 1 and 2, the multilayer board shield cover 3 is arranged in a U-shape by connecting two upper and lower parallel surfaces formed by the ground patterns 11 and 12 and both ends connected to the ground patterns 11 and 12. The plurality of ground vias (through VIA) 16 and the plurality of ground vias 15 arranged linearly along the side wall 50 form a rectangular parallelepiped dielectric waveguide 30 filled with a dielectric. In the dielectric waveguide 30, the slit 13 opened in the ground pattern 12 is provided at a position close to the ground via 15, and the slit 13 is covered with the resistance pattern 17 as described above. Further, a ground via 16 facing the ground via 15 is disposed at a position away from the resistance pattern 17 by λs / 4 wavelength. Here, λs is a connection portion (for example, a conductive line 31) with a transmission substrate (for example, the external terminal 29) of an RF (Radio Frequency) signal connected to the amplifier of the device component 1 or a microstrip line (for example, the signal pattern 24). ) Or the like is a wavelength that propagates in the dielectric 10. For example, the wavelength λ or the wavelength λ / 2 propagates in the dielectric 10 in the use band of the RF signal processed by the device component 1. It becomes equal to the wavelength in the vicinity.

The ground vias 16 are arranged in two regions on the inside of the facing side wall 50 so as to surround the slits 13 in accordance with the arrangement of the slits 13. A plurality of ground vias (through vias) 14 are appropriately arranged between the ground vias 16 arranged in these two regions.
The arrangement area of the ground vias 16 is not limited to two, and may be one or three or more.

The lowermost ground pattern 18 on the back surface side of the multilayer substrate shield cover 3 is bonded to the ground pattern 21 on the package 4 through the metal bumps 20. As a result, the device component 1 is accommodated in the cavity 60 formed in the multilayer substrate shield cover 3 and the package 4.
The metal bumps 20 are composed of solder, gold, silver bumps, and the like, and are joined by soldering, ultrasonic bonding, or pressure welding.

Next, the operation of the high-frequency module 100 according to the first embodiment will be described with reference to FIG.
From a connection portion (for example, a conductive line 31) with a transmission substrate (for example, the external terminal 29) of an RF (Radio Frequency) signal connected to the amplifier of the device component 1, a microstrip line (for example, the signal pattern 24), etc. Unnecessary electromagnetic waves having a wavelength of λs propagating in the space 10 leak in space.

In the high-frequency module 100, the internal space (cavity 60) in which the device component 1 is accommodated is obtained by bonding the ground pattern 18 of the multilayer substrate shield cover 3 to the ground pattern 21 of the package 4 through the metal bumps 20. It becomes an electromagnetically shielded closed space. Further, as shown in FIG. 1, electromagnetic shielding is performed by a multilayer substrate shield cover 3 made of a multilayer substrate in which front and back conductor patterns (ground patterns) are conducted through ground vias.
For this reason, since the inside of the high-frequency module 100 is short-circuited at the outer periphery, it is necessary to suppress resonance that may occur at multiples of λs / 2 due to standing waves in the parallel plate mode caused by unnecessary electromagnetic waves.

  For this reason, the multilayer substrate shield cover 3 of the first embodiment is provided with the slit 13 covered with the resistance pattern 17 at the short end of the standing wave due to the unnecessary electromagnetic wave generated inside the high frequency module 100. Yes. In addition, a dielectric waveguide 30 composed of front and back conductor patterns (ground patterns 11 and 12) and ground vias 15 and 16 is provided, and the dielectric is guided by the ground via 16 at a distance of λs / 4 from the resistance pattern 17. One end of the waveguide 30 is short-circuited. The other end of the dielectric waveguide 30 is made to allow unnecessary electromagnetic waves from entering and exiting from the cavity 60 through the slit 30 covered with the resistance pattern 17.

When the resistance pattern 17 is set equal to the impedance of the parallel plate mode, the outer periphery is terminated with a resistor, and standing waves due to unnecessary electromagnetic waves are suppressed.
The resistance pattern 17 and the λs / 4 dielectric waveguide 30 can be easily formed on the substrate, and a complicated-shaped cut-off block as in the conventional high-frequency module is not required. It is possible to reduce the size.

  As described above, in the high-frequency circuit module according to the first embodiment, the multilayer substrate shield cover 3 has the slit 13 having the conductor pattern opened at the short end of the standing wave standing in the inner closed space and the resistance pattern 17 covering the slit 13. And a short-end dielectric waveguide 30 comprising front and back conductor patterns and ground vias is provided to form a multilayer substrate. Further, in this dielectric waveguide 30, the length of the waveguide from the resistance pattern 17 to the short end is λs / 4.

  Further, the short-circuited end of the standing wave due to unnecessary electromagnetic waves is generated near the end interface of the internal space (cavity 60) formed by the multilayer substrate shield cover 3 and the package 5, and thus protrudes below the multilayer substrate shield cover 3. A protrusion (side wall 50) is provided to form a cavity for accommodating the device component 1, and a slit 13 serving as a dielectric window leading to the dielectric waveguide 30 is provided at a position adjacent to the inner surface of the protrusion. Yes.

  As a result, the short-circuited end of the standing wave becomes a resistance termination, so that the resonance due to the standing wave of unwanted electromagnetic waves is suppressed and good electrical characteristics with low loss are achieved without requiring a complicated cut-off structure inside the high-frequency module. Can be secured. In addition, since a complicated cut-off structure is not required inside the high-frequency module, it is possible to reduce the size of a package or shield cover that accommodates device components.

  Instead of providing a projecting portion (side wall 50) projecting below the multilayer substrate shield cover 3, a cavity for accommodating the device component 1 may be formed in the package 4, whereby the multilayer substrate shield cover 3 is formed. Becomes a simpler plate shape.

  As described above, the high-frequency module according to the first embodiment includes the dielectric substrate on which a plurality of via holes (ground vias) are arranged, and the ground formed on the front and back surfaces of the dielectric substrate and connected to the via holes. A conductor, a slit-shaped dielectric opening (slit 13) formed in the ground conductor on the back surface of the dielectric substrate, one end connected to the dielectric opening, and the other end being a partial via hole (ground via 16) ) A shield cover (multilayer substrate shield cover 3) having a dielectric waveguide (30) whose arrangement is a short end, and a resistor (resistive pattern 17) provided in the dielectric opening, and a high-frequency semiconductor (Device component 1) is placed, and the back surface of the shield cover is bonded via a conductive connection (metal bump 20) to accommodate the high-frequency semiconductor. A package (4) forming the that space, comprising the. The length between the dielectric opening and a part of the via hole arrangement is a quarter of the wavelength at which unnecessary electromagnetic waves of the high-frequency signal processed by the high-frequency semiconductor propagate in the dielectric substrate of the shield cover. 1 may be sufficient. Further, the unnecessary electromagnetic wave is generated in a signal transmission path between the high-frequency semiconductor and a signal terminal in the package, and the dielectric opening and the resistor are located at a short end of the standing wave due to the unnecessary electromagnetic wave. It may be arranged in.

  As a result, unnecessary resonance due to standing waves generated in the electromagnetically shielded internal space can be suppressed, good electrical performance can be ensured, and the high-frequency module can be reduced in size.

  1 device component (high frequency semiconductor), 3 multilayer board shield cover, 4 package, 5 chassis, 10 dielectric, 11 ground pattern, 12 ground pattern, 13 slit, 14, 15, 16 ground via, 17 resistance pattern, 19 ground via , 20 Metal bump (conductive connection part), 30 Dielectric waveguide, 50 Side wall (protrusion part), 60 Cavity.

Claims (5)

A dielectric substrate on which a plurality of vias are arranged; and
A ground conductor formed on the front and back surfaces of the dielectric substrate and connected to the via;
A dielectric opening formed in the ground conductor on the back surface of the dielectric substrate;
A dielectric waveguide having one end connected to the dielectric opening and the other end being a short end of a portion of the via arrangement;
A resistor provided in the dielectric opening;
A shield cover with
A package that forms a space for housing the high-frequency semiconductor by mounting the high-frequency semiconductor and bonding the back surface of the shield cover through the conductive connection portion;
High frequency module with   The length between the dielectric opening and a part of the via arrangement is a quarter of the wavelength at which unnecessary electromagnetic waves of the high-frequency signal processed by the high-frequency semiconductor propagate in the dielectric substrate of the shield cover. The high-frequency module according to claim 1, wherein The unnecessary electromagnetic wave is generated in a signal transmission path between the high-frequency semiconductor and a signal terminal in the package,
3. The high-frequency module according to claim 2, wherein the dielectric opening and the resistor are disposed at a position that becomes a short end of the standing wave due to the unnecessary electromagnetic wave.   The high frequency module according to any one of claims 1 to 3, comprising a high frequency semiconductor of a microwave band or a millimeter wave band. A dielectric substrate on which a plurality of vias are arranged; and
A ground conductor formed on the front surface of the dielectric substrate and the back surface to be joined to the external package on which the high-frequency semiconductor is placed, and connected to the via;
A dielectric opening provided in the ground conductor on the back surface of the dielectric substrate;
A dielectric waveguide having one end connected to the dielectric opening and the other end being a short end of a portion of the via arrangement;
A resistor provided in the dielectric opening;
Shield cover for high frequency module with

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