JP2014107847A - High-frequency module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent spatial noise from radiating from between a ground pattern of a filter and ground patterns of the other circuits.SOLUTION: A high-frequency module 101 includes a multilayer substrate 10 by a stack of base material layers 1a to 1d, and an IC chip 20 including a noise generating source NS and a high-frequency filter 21 and the like are mounted on the multilayer substrate 10. The multilayer substrate 10 includes ground patterns 2d and 2g of a high-frequency circuit and the like therein. The ground patterns of the high-frequency circuit are formed with a predetermined distance from a filter ground pattern 2h. The high-frequency filter 21 has an element body composed of a material having higher dielectric constant than a base material of the multilayer substrate 10. The high-frequency filter 21 is disposed so as to straddle at least a part of a gap between the filter ground pattern 2h and the ground pattern 2g of the high-frequency circuit.

Description

  The present invention relates to a high frequency module in which a high frequency circuit serving as a noise generation source is formed on a multilayer substrate.

  In order to reduce the size of an electronic device, it is always a technical problem how to mount components on a circuit board in the electronic device with high density. As a means for increasing the density, it is effective to modularize components to be mounted on a circuit board.

  Multilayer boards with built-in circuit patterns are used in various fields such as portable devices to meet the downsizing of electronic devices. In addition to small chip passive components such as capacitors and filters, ICs formed by a semiconductor process are mounted on the surface of such a multilayer substrate. The ground of these parts is preferably connected to the nearest ground pattern formed on the multilayer substrate by using an interlayer pattern or the like because this leads to suppression of an inductance component generated at the ground junction (Patent Document 1). reference).

Japanese Patent Laid-Open No. 2001-15585

  In recent years, IC development has progressed, and an IC including both an analog circuit portion and a digital circuit portion in a single-chip IC has been used. By using such an IC, the number of mounted components is reduced, and downsizing of electronic equipment is expected. On the other hand, in an IC in which such an analog circuit and a digital circuit are integrated into one chip, an oscillation circuit unit Reduction of noise generated from the problem has been a problem.

  Arranging the ground pattern in the vicinity of the noise generation source is effective for shielding the noise. However, noise that is induced in the ground pattern and noise that propagates through the ground pattern is superimposed on the ground potential of the filter, which may cause a problem that the original function of the filter is not performed. Therefore, it is effective to separate the ground portion coupled to the noise generation source from the filter ground.

  However, if the distance between the ground pattern of the filter and the ground pattern of other circuits becomes short as the module is downsized, there is a concern that spatial noise is radiated (leaked) to the outside from between the ground patterns.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a high-frequency module that suppresses radiation of spatial noise from between a ground pattern of a filter and a ground pattern of another circuit.

  The high-frequency module of the present invention is configured as follows.

(1) a multilayer substrate formed by laminating a plurality of base material layers;
A high-frequency filter mounted on or incorporated in the multilayer substrate to control the passband;
A filter ground pattern formed in the multilayer substrate and connected to a ground terminal of the high-frequency filter;
In a high-frequency module provided with a high-frequency circuit that is built in the multilayer substrate or disposed on the surface and serves as a noise generation source,
The ground pattern of the high-frequency circuit is formed in the multilayer substrate with a predetermined gap from the filter ground pattern,
The high-frequency filter has an element body made of a material having a higher dielectric constant than the base material of the multilayer substrate,
The high-frequency filter is disposed so as to straddle at least a part of a gap between the filter ground pattern and the ground pattern of the high-frequency circuit.

  With this configuration, spatial noise that is about to be radiated from the gap between the filter ground pattern and the ground pattern of the high-frequency circuit is shielded (reflected) by the dielectric base material of the high-frequency filter, and leakage of the spatial noise to the outside is suppressed. .

(2) It is preferable that the high frequency filter is disposed so as to straddle a region where the gap distance is smallest among the gaps. With this structure, the shielding effect by the high frequency filter is enhanced.

(3) The base material layer is preferably made of a liquid crystal polymer. As a result, high-frequency main signals can be transmitted with low loss due to the effect of low dielectric constant and low dielectric loss. Further, the contrast between the dielectric constant of the multilayer substrate and the dielectric constant of the base material of the high frequency filter is increased, and the shielding effect of the dielectric base material of the high frequency filter is enhanced.

(4) It is preferable that the filter ground pattern and the ground pattern are independently connected to a mounting terminal electrode formed on the multilayer substrate. With this structure, the path between the ground of the high-frequency circuit and the ground of the high-frequency filter becomes long, and noise superposition from the ground pattern of the high-frequency circuit to the ground of the high-frequency filter is further suppressed.

  According to the present invention, spatial noise that is about to be radiated from the gap between the filter ground pattern and the ground pattern of the high-frequency circuit is shielded (reflected) by the dielectric base material of the high-frequency filter, and leakage of the spatial noise to the outside is suppressed. Is done.

FIG. 1 is a cross-sectional view showing the structure of the high-frequency module 101 according to the first embodiment. FIG. 2 is a block diagram of a circuit configured in the high frequency module 101. FIG. 3 is a cross-sectional view showing the structure of the high-frequency module 102 according to the second embodiment. FIG. 4 is a partial cross-sectional view on a plane passing through the high frequency filter 21. FIG. 5 is a diagram showing conductor patterns formed in each layer constituting the multilayer substrate. FIG. 6 is a cross-sectional view of the IC chip 20 embedded in the multilayer substrate 10. FIG. 7 is a diagram illustrating a manufacturing process of the high-frequency module 102. FIG. 8 is a sectional view showing the structure of the high-frequency module 103 according to the third embodiment.

<< First Embodiment >>
FIG. 1 is a cross-sectional view showing the structure of the high-frequency module 101 according to the first embodiment. The high-frequency module 101 is configured on a multilayer substrate 10 formed by stacking insulating base layers 1a to 1d.

  On the lower surface of the multilayer substrate 10, mounting terminals 2a, 2b and the like are formed. Component mounting electrodes 2i, 2j, 2k, 2m and the like are formed on the upper surface of the multilayer substrate 10. In the multilayer substrate 10, ground patterns 2d and 2g extending in a planar shape, and other conductor patterns 2e, 2f and 2h are formed. In addition, interlayer connection conductors (via conductors) 3 a to 3 h are formed on the multilayer substrate 10.

  An IC chip 20 and a high frequency filter 21 are mounted on the upper surface of the multilayer substrate 10. The IC chip 20 is a component including a noise generation source NS. The high frequency filter 21 is formed by forming an electrode on a substrate of a high dielectric constant material.

  The ground terminal of the IC chip 20 is connected to the ground pattern 2g via the component mounting electrode 2m and the interlayer connection conductor 3g. The ground pattern 2g is connected to the ground pattern 2d through the interlayer connection conductors 3f and 3d and the conductor pattern 2f. On the other hand, the ground terminal of the high frequency filter 21 is connected to the ground pattern 2d via the component mounting electrode 2k, the interlayer connection conductors 3h, 3e, 3c, and the conductor patterns 2h, 2e. The conductor pattern 2h corresponds to a “filter ground pattern” according to the present invention. The ground pattern 2d is connected to the mounting terminals 2a and 2b via the interlayer connection conductors 3a and 3b. Thus, the conductor pattern (filter ground pattern) 2h to which the ground terminal of the high frequency filter is connected is separated from the ground pattern 2g to which the ground terminal of the IC chip 20 is connected.

  FIG. 2 is a block diagram of a circuit configured in the high frequency module 101. The high frequency module 101 includes an IC chip 20, a high frequency filter 21, and a serial data input / output controller 23. The IC chip 20 includes a balanced / unbalanced conversion circuit 20b, an analog front end circuit 20c, a baseband circuit 20d, a control circuit 20e, and an oscillation circuit 20a. Here, the analog front-end circuit 20c is a high-frequency circuit unit in the physical layer in the communication protocol, and the baseband circuit 20d is a baseband circuit unit in the physical layer in the communication protocol.

  A crystal oscillator 22 mounted on a multilayer substrate is connected to the oscillation circuit 20a and oscillates, and a high-frequency signal and a clock signal having a predetermined frequency are generated by a PLL circuit. The oscillation circuit 20a corresponds to the noise generation source NS. Examples of the noise generation source NS include a frequency dividing circuit in addition to the oscillation circuit.

  Returning to FIG. 1, noise is induced in the ground pattern 2 g by the electromagnetic field generated by the noise generation source NS of the IC chip 20. Since the ground pattern 2g is separated from the conductor pattern (filter ground pattern) 2h to which the ground terminal of the high frequency filter is connected, the ground pattern 2g and the conductor pattern 2h have a potential difference, and the ground pattern 2g and the conductor A gap with the pattern 2h acts like a slot antenna. That is, this gap becomes a noise radiation source NR, and noise is radiated as an electromagnetic wave. However, since the base of the high frequency filter 21 has a dielectric constant higher than the dielectric constant of the base layer of the multilayer substrate 10, the electromagnetic wave radiated from the noise radiation source NR is reflected by the dielectric base of the high frequency filter 21, and the high frequency module 101. Is hardly radiated to the outside.

  The high frequency filter 21 is preferably disposed so as to straddle the region where the gap distance is the smallest among the gaps between the ground pattern 2g and the conductor pattern 2h. Thereby, the shielding effect by the high frequency filter is enhanced.

  The dielectric substrate of the high frequency filter 21 is a high dielectric ceramic having a relative dielectric constant of 15 or more. For example, the dielectric substrate is made of a high dielectric constant dielectric such as alumina, silica, barium and glass material. On the other hand, the base material of the multilayer substrate is, for example, a low dielectric constant resin having a relative dielectric constant of less than 5. For example, a liquid crystal polymer having a relative dielectric constant ≈3. By using a liquid crystal polymer as a base material, high-frequency main signals can be transmitted with low loss due to the effect of low dielectric constant and low dielectric loss. Further, the contrast between the dielectric constant of the multilayer substrate and the dielectric constant of the base material of the high frequency filter is increased, and the shielding effect of the dielectric base material of the high frequency filter is enhanced.

<< Second Embodiment >>
FIG. 3 is a cross-sectional view showing the structure of the high-frequency module 102 according to the second embodiment. The high-frequency module 102 is configured on a multilayer substrate 10 formed by stacking insulating base layers 1a to 1f.

  On the lower surface of the multilayer substrate 10, mounting terminals 2a, 2b and the like are formed. Component mounting electrodes 2k and the like are formed on the upper surface of the multilayer substrate 10. In the multilayer substrate 10, ground patterns 2c, 2d, 2g extending in a planar shape, and other conductor patterns 2e, 2f, 2n, 2h, 2p and the like are formed. The multilayer substrate 10 is provided with interlayer connection conductors (via conductors) 3a to 3h, 3d1, 3d2, and the like.

  A high frequency filter 21 is mounted on the upper surface of the multilayer substrate 10. The high-frequency filter 21 is formed by forming an electrode on a substrate of a high dielectric constant material, and the dielectric substrate has a dielectric constant higher than that of the base material layer of the multilayer substrate 10.

  A cavity 4 is formed inside the multilayer substrate 10, and an IC chip 20 is disposed (embedded) in the cavity 4. The IC chip 20 is a component including a noise generation source NS.

  FIG. 4 is a partial cross-sectional view on a plane passing through the high frequency filter 21. However, it is a cross-sectional view in a plane orthogonal to the cross section shown in FIG. The high-frequency filter 21 is a bandpass filter including a dielectric substrate, a resonance electrode and a terminal electrode formed on the dielectric substrate. In FIG. 4, the high-frequency filter 21 includes signal input / output terminals S1 and S2 and a ground terminal G.

  FIG. 5 is a diagram showing conductor patterns formed on each layer constituting the multilayer substrate. Each of these figures is a top view of an insulating base material layer (hereinafter simply referred to as “base material layer”). 3 is a cross-sectional view taken along line AA in FIG. FIG. 4 is a CC cross section in FIG.

  In FIG. 5, the base material layer 1f is the uppermost layer, and an electrode for mounting the high frequency filter 21 is formed on the base material layer 1f. A ground pattern 2g is formed on the upper surface of the base material layer 1e, and an interlayer connection conductor 3n is formed inside. A cavity 4 (opening) is formed in the base material layer 1d. Conductive patterns 2p and 2n are formed on the upper surface of the base material layer 1d. A ground pattern 2d and the like are formed on the lower surface of the base material layer 1c, and interlayer connection conductors 3e and 3f and the like are formed therein. A ground pattern 2c is formed on the lower surface of the base material layer 1b, and interlayer connection conductors 3d1, 3d2 and the like are formed therein. A plurality of mounting terminals are formed on the lower surface of the base material layer 1a, and interlayer connection conductors 3a, 3b and the like are formed therein.

  FIG. 6 is a cross-sectional view of the IC chip 20 embedded in the multilayer substrate 10. A predetermined high-frequency circuit is formed on the circuit forming layer CR on the surface (the lower surface side in the direction of FIG. 6) of the substrate SU of the IC chip 20. The rewiring layer RW is formed on the surface of the circuit forming layer CR, and the electrode pad PD is exposed on the surface of the rewiring layer RW. The interlayer connection conductor exposed on the inner surface of the cavity 4 of the multilayer substrate 10 is electrically connected.

  As described above, since the two ground patterns 2d and 2g are formed so as to sandwich the cavity 4 (noise generation source NS) in the layer direction, the ground patterns 2d and 2g are shield plates of the noise generation source NS. Acts as

  As in the case of the first embodiment, noise is induced in the ground pattern 2g by the electromagnetic field generated by the noise generation source NS of the IC chip 20, and the gap between the ground pattern 2g and the conductor pattern 2h becomes a noise radiation source NR. Acts as However, similarly to the case of the first embodiment, since the high frequency filter 21 exists above the conductor pattern 2h, the electromagnetic wave radiated from the noise radiation source NR is reflected by the dielectric substrate of the high frequency filter 21, There is almost no radiation (radiation) to the outside of the high-frequency module 102.

  FIG. 7 is a diagram showing a manufacturing process of the high-frequency module 102. In FIG. 7, (1) to (4) are cross-sectional views in each process. These correspond to the BB cross section shown in FIG.

  The wiring pattern formed on the resin layer is formed, for example, by removing the copper foil attached to the resin sheet by etching. The interlayer connection conductor is formed by forming a via hole in the resin sheet, injecting a conductive paste into the formed via hole, and solidifying by heating at the time of batch lamination. That is, conduction between the copper foils of the resin sheet is ensured by this interlayer connection conductor.

  As shown in FIG. 7 (1), a cavity 4 is formed by a laminate of a base material layer 1 d with openings and base material layers 1 a, 1 b, 1 c without openings, and an IC chip is formed in the cavity 4. 20 is installed, and then, as shown in (2), the laminated body by the base material layers 1e and 1f is covered. Then, it heat-presses as shown in (3). Thereafter, as shown in (4), components such as the high frequency filter 21 are surface-mounted on the multilayer substrate 10.

  The high frequency module 102 is configured as described above. The high frequency module 102 is surface-mounted on a mounting substrate.

  As shown in this embodiment, a module can be reduced in size by incorporating an IC chip including a noise generation source in a multilayer substrate. However, since the distance between the ground patterns is shortened, the noise outlet is easily limited spatially. Spatial noise is likely to occur. Therefore, the present invention is particularly effective in a high-frequency module in which an IC chip including a noise generation source is built in a multilayer substrate.

<< Third Embodiment >>
FIG. 8 is a sectional view showing the structure of the high-frequency module 103 according to the third embodiment. The high-frequency module 103 is configured on a multilayer substrate 10 formed by stacking insulating base layers 1a to 1d. Unlike the example shown in FIG. 1, the filter ground pattern 2h and the ground pattern 2g are independently connected to the mounting terminal electrodes 2a and 2b. With this structure, the path between the ground of the high-frequency circuit and the ground of the high-frequency filter 21 becomes long, and the superposition of noise from the ground pattern of the high-frequency circuit to the ground of the high-frequency filter 21 is further suppressed.

  In each of the above-described embodiments, the example in which the high frequency filter is mounted on the upper surface of the multilayer substrate has been described. However, the high frequency filter may be built in the multilayer substrate. Even in such a case, the high frequency filter may be disposed so as to straddle at least a part of the gap between the filter ground pattern and the ground pattern of the high frequency circuit.

  In each of the embodiments described above, an example is shown in which an interlayer connection conductor is formed by forming a via hole in a resin sheet, injecting a conductive paste into the formed via hole, and solidifying by heating during batch lamination. A structure using a metal rivet or a structure in which a through hole is formed and the inner surface thereof is plated may be used. Further, a structure in which interlayer connection is performed by conductive bumps embedded in an insulating layer in advance may be employed. For example, the interlayer connection may be performed by printing a silver paste on a copper foil, forming a conical protrusion (bump), penetrating the prepreg, and laminating and pressing with the opposing copper foil.

CR ... Circuit forming layer NR ... Noise radiation source NS ... Noise source PD ... Electrode pad RW ... Redistribution layer SU ... Substrate 1a to 1f ... Insulating substrate layers 2a, 2b ... Mounting terminals 2c, 2d, 2g ... Ground pattern 2e, 2f, 2h, 2n, 2p ... Conductor pattern 2h ... Filter ground pattern 2i, 2j, 2k, 2m ... Component mounting electrodes 3a to 3h, 3d1, 3d2 ... Interlayer connection conductor 4 ... Cavity 10 ... Multilayer substrate 20 ... IC chip 20a ... oscillation circuit 20b ... unbalance conversion circuit 20c ... analog front end circuit 20d ... baseband circuit 20e ... control circuit 21 ... high frequency filter 22 ... crystal oscillator 23 ... serial data input / output controllers 101, 102 ... high frequency module

Claims (4)

A multilayer substrate formed by laminating a plurality of base material layers;
A high-frequency filter mounted on or incorporated in the multilayer substrate to control the passband;
A filter ground pattern formed in the multilayer substrate and connected to a ground terminal of the high-frequency filter;
In a high-frequency module provided with a high-frequency circuit that is built in the multilayer substrate or disposed on the surface and serves as a noise generation source,
The ground pattern of the high-frequency circuit and the filter ground pattern are formed in the multilayer substrate through a predetermined gap,
The high-frequency filter has an element body made of a material having a higher dielectric constant than the base material of the multilayer substrate,
The high-frequency module, wherein the high-frequency filter is disposed so as to straddle at least a part of a gap between the filter ground pattern and the ground pattern of the high-frequency circuit.   The high-frequency module according to claim 1, wherein the high-frequency filter is disposed so as to straddle a region where the gap distance is smallest among the gaps.   The high-frequency module according to claim 1, wherein the base material layer is made of a liquid crystal polymer.   The high-frequency module according to claim 1, wherein the filter ground pattern and the ground pattern are independently connected to a mounting terminal electrode formed on the multilayer substrate.

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