In a high-frequency module, an antenna device is disposed on a first principal surface of a second substrate, a first principal surface of a first substrate and a second principal surface of the second substrate face each other and are connected to each other by conductive connecting members, electronic components including an IC chip are mounted on the first principal surface of the first substrate, ground electrodes are disposed on the first and second substrates, the conductive connecting members are connected to a ground potential, and thus the IC chip is surrounded by the ground electrodes of the first and second substrates and the conductive connecting members.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a high-frequency module defined by combining a plurality of devices including an antenna, and more particularly, to a high-frequency module having a structure in which a substrate provided with an antenna and another substrate provided with a high-frequency device are joined together.

2. Description of the Related Art

To reduce the size of communication equipment, such as mobile phones, various types of high-frequency modules defined by combining a plurality of devices including an antenna are used.

For example, Japanese Unexamined Patent Application Publication No. 2005-19649 discloses a high-frequency module illustrated inFIG. 12.

Referring toFIG. 12, a high-frequency module101has a laminated structure including a first dielectric substrate103having an antenna conductor102on an upper surface thereof, and a second dielectric substrate104having a recessed portion104ain a lower surface thereof. A high-frequency device105and an antenna-characteristic measuring connector106are disposed in the recessed portion104a.

A ground conductor107connected to a ground potential is disposed under substantially the entire lower surface of the first dielectric substrate103. The ground conductor107has a through hole through which a through hole conductor108extends so as not to come into contact with the ground conductor107. An upper end and a lower end of the through hole conductor108are connected to the antenna conductor102and the antenna-characteristic measuring connector106, respectively.

In the high-frequency module101, a terminal electrode109is disposed in a lower surface of a frame portion around the recessed portion104aof the second dielectric substrate104. The terminal electrode109is connected to a high-frequency circuit including the high-frequency device105. Also, the terminal electrode109is connected to an electrode land111on a mounting board110, with a conductive joining member112interposed between the terminal electrode109and the electrode land111.

In the high-frequency module101, the antenna-characteristic measuring connector106is disposed in the recessed portion104ain the lower surface of the second dielectric substrate104. Since the antenna-characteristic measuring connector106is disposed below the ground conductor107, electromagnetic fields radiated from the antenna are not transmitted to the measuring probe. Therefore, Japanese Unexamined Patent Application Publication No. 2005-19649 states that it is possible to measure the antenna characteristics that are unaffected by the electromagnetic fields.

In the high-frequency module101, the first dielectric substrate103having the antenna conductor102on the upper surface thereof and the second dielectric substrate104having the high-frequency device105on the lower surface thereof are directly stacked together to define an integrated unit.

At the same time, since the intensity of the radio waves radiated from the antenna including the antenna conductor102is relatively high, the radio waves propagate from above the antenna conductor102to the high-frequency circuit including the high-frequency device105. Therefore, although the antenna conductor102and the high-frequency device105are separated from each other by the ground conductor107, the radio waves from the antenna conductor102cause fluctuations in the characteristics of the high-frequency circuit including the high-frequency device105. That is, although the ground conductor107is disposed above the high-frequency circuit including the high-frequency device105, there is a tendency that radio waves from the antenna conductor102are partially transmitted around the ground conductor107and affect the high-frequency circuit including the high-frequency device105.

SUMMARY OF THE INVENTION

To overcome the problems described above, preferred embodiments of the present invention provide a high-frequency module defined by combining a plurality of devices including an antenna to achieve compactness that is less susceptible to the adverse effect of radio waves radiated from the antenna, and thus having outstanding reception or transmission performance.

A high-frequency module according to a preferred embodiment of the present invention includes a first substrate having first and second principal surfaces and provided with a ground layer connected to a wiring layer and to a ground potential, a mounted component on the first principal surface of the first substrate, a second substrate having first and second principal surfaces and provided with a ground layer, and an antenna device on the first principal surface of the second substrate. The first principal surface of the first substrate and the second principal surface of the second substrate are disposed to face each other. The high-frequency module further includes a conductive connecting member connected to the ground potential and connecting the first principal surface of the first substrate and the second principal surface of the second substrate.

Preferably, the conductive connecting member is disposed around the mounted component.

Preferably, the conductive connecting member is a columnar member.

Alternatively, the conductive connecting member may be a plate-like member extending to connect the first and second substrates.

Preferably, more than one conductive connecting member is provided.

Preferably, signal terminals are provided which connect the principal surfaces of the first and second substrates and through which signal currents flow.

At least a portion of the conductive connecting member, other than portions connected to the first and second substrates, is preferably coated with an insulating material.

The insulating material preferably has a frame shaped member disposed around the mounted component, and the conductive connecting member is embedded in the frame shaped member.

Preferably, the insulating material is a synthetic resin.

The mounted component is preferably an active component.

The area of the ground layer in the second substrate is preferably greater than the area of the first principal surface of the first substrate.

Preferably, the first and second principal surfaces of the second substrate each have a ground layer disposed thereon.

The ground layer in the first substrate and the ground layer in the second substrate are preferably separated from each other.

The first principal surface of the second substrate is preferably provided with a coplanar line in addition to the antenna device.

Preferably, the permittivity of a material of which the second substrate is made is less than the permittivity of a material of which the first substrate is made.

The first substrate preferably includes a plurality of substrate layers, and a wiring layer is interposed between at least one pair of adjacent substrate layers of the plurality of substrate layers.

The ground layer is preferably interposed between at least one pair of adjacent substrate layers of the plurality of substrate layers.

The mounted component on the first principal surface of the first substrate is preferably sealed with a resin-sealing layer.

Preferably, a gap is created between an upper surface of the resin-sealing layer and the second principal surface of the second substrate.

In the high-frequency module according to preferred embodiments of the present invention, the mounted component is on the first principal surface of the first substrate and the antenna device is on the first principal surface of the second substrate. The first substrate and the second substrate are disposed such that the first principal surface of the first substrate and the second principal surface of the second substrate face each other, the second principal surface being opposite the first principal surface of the second substrate. The first principal surface of the first substrate and the second principal surface of the second substrate are connected to each other by the conductive connecting member.

The antenna device is disposed on the first principal surface of the second substrate having the ground layer. Therefore, the propagation of radio waves from the antenna device to the first substrate is blocked by the ground layer of the second substrate. Moreover, the first substrate and the second substrate are not directly stacked together and are disposed such that the first principal surface of the first substrate and the second principal surface of the second substrate face each other and are joined to each other by the conductive connecting member. Therefore, the effects of radio waves radiated from the antenna device on the mounted component are significantly reduced.

Additionally, the conductive connecting member, which is connected to the ground potential, also reduces the effects of radio waves radiated from the antenna on the mounted component.

Therefore, with preferred embodiments of the present invention, in the high-frequency module defined by combining a plurality of devices including the antenna and the mounted component, it is possible to reduce fluctuations in characteristics caused by radio waves radiated from the antenna and to effectively improve reception and transmission performance.

In particular, when the conductive connecting member is disposed around the mounted component, it is possible to more effectively reduce the effects of radio waves radiated from the antenna on the mounted component.

When the conductive connecting member is a columnar member, a gap can be created between the first and second substrates by connecting ends of the conductive connecting member to the first principal surface of the first substrate and the second principal surface of the second substrate, respectively. At the same time, by connecting the conductive connecting member to the ground potential, the gap can be reliably electromagnetically shielded.

When the conductive connecting member is a plate-like member extending to connect the first and second substrates, the inner region of the plate-like member can be more reliably electromagnetically shielded by connecting the plate-like member to the ground potential. Thus, the effects of radio waves radiated from the antenna can be further reduced.

When more than one conductive connecting member is provided, the effects of radio waves radiated from the antenna on the mounted component can be more effectively reduced.

When signal terminals which connect the principal surfaces of the first and second substrates and through which signal currents flow are provided, an electrical connection between the antenna device and the mounted component can be established by the signal terminals. In this case, it is only necessary to determine the number and arrangement of conductive connecting members such that the effect of radio waves radiated from the antenna on the mounted component can be reduced. Thus, since a higher degree of design freedom is achieved, it is easier to further reduce the effects of radio waves radiated from the antenna on the mounted component.

When at least a portion of the conductive connecting member, other than portions connected to the first and second substrates, is coated with an insulating material, it is possible to reduce short circuits and variations in characteristics caused by contact of conductive material and metal powders with the conductive connecting member. At the same time, it is possible to improve environmental resistance, such as moisture resistance.

When the insulating material is defined by a frame shaped member disposed around the mounted component and the conductive connecting member is embedded in the frame shaped member, the mounted component is reliably enclosed by the frame shaped member of insulating material. Therefore, it is possible to improve moisture resistance and environmental resistance. Additionally, since the conductive connecting member is disposed around the mounted component, fluctuations in characteristics caused by the effects of radio waves radiated from the antenna can be more reliably prevented. At the same time, since the permittivity of the frame shaped member is less than that of the first substrate, the resonance associated with a wavelength shortening effect occurs at frequencies greater than those used in the high-frequency module. Therefore, it is possible to reduce the degradation in the characteristics of the high-frequency module caused by the resonance.

When the insulating material is a synthetic resin, it is easy to form an insulating layer around the conductive connecting member.

When the mounted component is an active component, which is a very important component for providing a module function and high-frequency characteristics, the effects of the external environment, such as the antenna, on the active component must be minimized. Accordingly, when the active component is mounted in a region surrounded by the conductive connecting member and GND electrodes, the effects of electromagnetic fields radiated from the antenna on the active component can be effectively reduced. Thus, excellent and stable high-frequency characteristics can be achieved.

When the area of the ground layer in the second substrate is greater than the area of the first principal surface of the first substrate, the propagation of radio waves radiated from the antenna device to the first substrate can be more effectively suppressed.

When the first and second principal surfaces of the second substrate each have a ground layer thereon, it is possible to effectively reduce the effects of radio waves radiated from the antenna device on the mounted component disposed on the first substrate.

When the ground layer in the first substrate and the ground layer in the second substrate are separated from each other, the mounted component can be more effectively electromagnetically shielded by individually connecting these ground layers to the ground potential.

When the first principal surface of the second substrate is provided with a substantially coplanar line as well as the antenna device, the structure of the high-frequency module is substantially planar. Therefore, the size and profile of the high-frequency module can be reduced.

When the permittivity of a material of which the second substrate is made is less than the permittivity of a material of which the first substrate is made, the resonance associated with a wavelength shortening effect occurs at frequencies higher than those used in the high-frequency module. Therefore, it is possible to reduce degradation in the characteristics of the high-frequency module caused by the resonance.

When the first substrate includes a plurality of substrate layers, and a wiring layer is interposed between at least one pair of adjacent substrate layers of the plurality of substrate layers, the formation of a high-frequency circuit and higher-density wiring are facilitated. As a result, a large-scale high-frequency circuit can be constructed in a relatively small area.

When the ground layer is interposed between at least one pair of adjacent substrate layers of the plurality of substrate layers, it is possible to reduce the effects of radio waves on the mounted component disposed on the first substrate, the radio waves being transmitted to the lower surface of the first substrate. Thus, reception and transmission performance can be further improved.

When the mounted component on the first principal surface of the first substrate is sealed with a resin-sealing layer, it is possible to improve environmental resistance characteristics of the high-frequency module.

When a gap is created between an upper surface of the resin-sealing layer and the second substrate, the permittivity significantly changes in the region between the antenna device and the mounted component. At the same time, since a gap layer with very low permittivity is created, it is possible to more effectively reduce the effect of electromagnetic fields radiated from the antenna on the mounted component.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, the present invention will be described by explaining specific preferred embodiments of the present invention with reference to the drawings.

FIG. 1AandFIG. 1Bare front cross-sectional views of a high-frequency module according to a preferred embodiment of the present invention.FIG. 1Ais a cross-sectional view taken along line A-A ofFIG. 2.FIG. 1Bis a cross-sectional view taken along line B-B ofFIG. 2. A high-frequency module1includes a first substrate2and a second substrate3. The first substrate2has an upper surface2adefining a first principal surface and a lower surface2bdefining a second principal surface.

The first substrate2is made of dielectric ceramic material having a permittivity greater than that of the second substrate3.

The second substrate3is made of synthetic resin material having a relatively low permittivity. Examples of such synthetic resin materials include, but are not specifically limited to, polyimide resin, epoxy resin, and glass epoxy resin.

As illustrated in the schematic plan view ofFIG. 2, a ground electrode4is provided, as a ground layer, over substantially an entire upper surface3adefining a first principal surface of the second substrate3.

An antenna device5is mounted on the upper surface3aof the second substrate3. The antenna device5is connected to one end of an L-shaped coplanar line6on the upper surface3a. The other end of the coplanar line6is connected to an electrode pad7a.

The electrode pad7ais connected to a through hole electrode9B, which is connected to an RF terminal12A defining a signal terminal.

An electrode pad7bis disposed on the upper surface3aof the second substrate3. The electrode pad7bis connected to a through hole electrode9C, which is connected to a bias terminal12B defining a signal terminal.

The antenna device5may be any appropriate antenna device, such as a dielectric antenna.

The ground electrode4and the coplanar line6can be formed by coating the upper surface3aof the substrate3with appropriate metallic material, such as Al or Cu, and patterning the coated upper surface3a. Although the coplanar line6preferably has a substantially L-shaped configuration in the present preferred embodiment, the shape of the coplanar line6is not specifically limited thereto.

In the present preferred embodiment, the first substrate2is connected to a lower surface3bdefining a second principal surface of the second substrate3by a plurality of conductive connecting members8. That is, the lower surface3bof the second substrate3and the upper surface2aof the first substrate2are connected to each other by the conductive connecting members8.

As illustrated in the bottom view ofFIG. 3, a ground electrode9is on the lower surface3bof the second substrate3.

As illustrated inFIG. 4, in addition to the ground electrode4and the ground electrode9provided on the respective upper and lower surfaces of the second substrate3, a ground electrode9A may be provided in a central portion of the second substrate3. Here, an electrode pad7connected to the coplanar line6is electrically connected to a wiring layer including the through hole electrode9B extending outward to the upper surface so as not to come into contact with the ground electrode9A. The wiring layer including the through hole electrode9B is connected to a high-frequency circuit (described below) by a signal terminal (described below).

Referring back toFIG. 3, the ground electrode9includes an opening9a, in which the plurality of conductive connecting members8are connected to corresponding electrode pads10on the lower surface3bof the second substrate3.

In the present preferred embodiment, the plurality of conductive connecting members8are embedded in a rectangular or substantially rectangular frame shaped member11made of synthetic resin. That is, as illustrated in the plan view ofFIG. 5, the frame shaped member11is secured to the upper surface2aof the first substrate2. The plurality of rectangular columnar conductive connecting members8are embedded in the frame shaped member11. The upper end and lower end of each conductive connecting member8protrude upward and downward from the upper and lower surfaces, respectively, of the frame shaped member11made of synthetic resin. It is only necessary for the upper end and lower end of each conductive connecting member8to be exposed from at least the upper and lower surfaces, respectively, of the frame shaped member11. As illustrated inFIGS. 1A and 1B, the upper ends of the conductive connecting members8are electrically connected to the corresponding electrode pads10.

The electrode pads10may be electrically connected to the ground electrode9. The conductive connecting members8are electrically connected to the ground potential as described below. As described below, the conductive connecting members8are electrically connected to the ground potential.

In the present preferred embodiment, signal terminals12in addition to the conductive connecting members8are embedded in the frame shaped member11. Similar to the conductive connecting members8, the signal terminals12each preferably have a rectangular columnar shape and protrude upward and downward from the upper and lower surfaces, respectively, of the frame shaped member11. That is, the plurality of conductive connecting members8and the RF terminal12A and the bias terminal12B defining signal terminals are embedded in a similar manner in the frame shaped member11.

The upper end of the RF terminal12A is electrically connected to the electrode pad7electrically connected to the coplanar line6. The RF terminal12A electrically connects the antenna device5to the high-frequency circuit (described below) so as to allow a signal current to flow.

On the other hand, the plurality of conductive connecting members8are connected to the ground potential and electromagnetically shield a region surrounded by the frame shaped member11.

Examples of synthetic resins of which the frame shaped member11is made include, but are not specifically limited to, polyimide resin, epoxy resin, and glass epoxy resin.

As illustrated inFIGS. 1A and 1B, the lower ends of the conductive connecting members8are connected to the first substrate2. Specifically, the lower ends of the conductive connecting members8are connected to corresponding electrode pads14on the upper surface2aof the first substrate2. The connection method is not limited to a specific one. The conductive connecting members8may be connected to the corresponding electrode pads14with conductive joining material, such as solder.

The conductive connecting members8allow connection between the upper surface of the first substrate and the lower surface of the second substrate. This means that the conductive connecting members8mechanically connect the first and second substrates. In other words, the conductive connecting members8do not necessarily have to electrically connect an electrode or the like of the first substrate2and that of the second substrate3. That is, as long as the conductive connecting members8are connected to the ground potential, the conductive connecting members8do not have to be capable of electrically connecting the first substrate2and the second substrate3.

The electrode pads14are connected to the ground potential. This allows the plurality of conductive connecting members8to be electrically connected to the ground potential.

An IC chip16and a high-frequency device17are mounted on the upper surface2aof the first substrate2. The IC chip16and the high-frequency device17each correspond to a mounted component. Of these mounted components, the IC chip16corresponds to an active component. When the mounted component is an active component, which is a very important component for providing a module function and high-frequency characteristics, the effect of the external environment, such as the antenna, on the active component must be effectively reduced. Accordingly, when the active component is mounted in a region surrounded by the conductive connecting members and GND electrodes, the effects of electromagnetic fields radiated from the antenna on the active component can be effectively reduced. Thus, outstanding and stable high-frequency characteristics can be achieved.

The IC chip16and the high-frequency device17are electrically connected to electrodes (not shown) on the upper surface of the first substrate2by wire bonding. The IC chip16and the high-frequency device17are resin-molded by a resin-coating layer18. Since the IC chip16and the high-frequency device17are resin-molded by the resin-coating layer18, environmental resistance characteristics of the high-frequency circuit including the IC chip16and the high-frequency device17are improved. The resin-coating layer18may be made of any suitable resin material, such as epoxy resin or silicon resin.

An upper surface18aof the resin-coating layer18is located under the second substrate3and a gap A. Since the gap A is provided, the permittivity significantly changes in the region from the second substrate3to the gap A, and the permittivity in the gap A is extremely small. Therefore, even if electromagnetic fields radiated from the side of the antenna device5and coplanar line6propagate downward, the effects of the electromagnetic fields on the high-frequency circuit including the IC chip16can be reduced. Therefore, it is preferable that the height of the resin-coating layer18be less than the distance between the first and second substrates2and3so that the gap A is created therebetween.

Electronic component devices19and20are mounted on the lower surface2bof the first substrate2. In the present preferred embodiment, the high-frequency circuit includes the IC chip16and a high-frequency device17mounted on the upper surface2aof the first substrate2and the electronic component devices19and20mounted on the lower surface2bof the first substrate2. Since the electronic component devices19and20can be mounted on both the upper surface2aand lower surface2bof the first substrate2, the size of the high-frequency module1can be reduced.

Although the electronic component devices19and20are surface-mounted with solder or other suitable conductive adhesive, they may be mounted on the lower surface2bof the first substrate2via bonding wires, as in the case of the IC chip16.

FIG. 6is a detailed cross-sectional view illustrating an exemplary structure of the first substrate2, which is schematically illustrated inFIGS. 1A and 1B.

In the present preferred embodiment, the first substrate2is a multilayer substrate formed by stacking and co-firing a plurality of ceramic layers. Preferably, the first substrate2is a low-temperature fired multilayer substrate in which at least one of a plurality of dielectric ceramic layers is a contraction suppressing layer. With such a low-temperature fired multilayer substrate having a contraction suppressing layer, it is possible to form wiring that has outstanding stability and precision. The first substrate2may be a single layer. The material of the first substrate2is not specifically limited to a dielectric ceramic.

As illustrated inFIG. 6, ground electrodes23and24are disposed on the upper surface2aof the first substrate2. The ground electrode23is electrically connected through a through hole electrode25to an internal ground electrode27, while the ground electrode24is electrically connected through a through hole electrode26to an internal ground electrode28. The ground electrode27is electrically connected through a through hole electrode29ato a ground electrode30aon the lower surface2bof the first substrate2, while the ground electrode28is electrically connected through a through hole electrode29bto a ground electrode30bon the lower surface2bof the first substrate2. Thus, the first substrate2also has a ground layer.

Besides the electrodes connected to the ground potential described above, an internal electrode32is provided inside the first substrate2. Internal electrodes including the internal electrode32electrically connect the IC chip16and high-frequency device17to the electronic component devices19and20mounted on the lower surface2bof the first substrate2, thereby forming the high-frequency circuit. In other words, a wiring layer of the high-frequency circuit is included in the first substrate2.

In the high-frequency module1of the present preferred embodiment, the ground electrodes4and9are disposed on the upper surface3aand lower surface3bof the second substrate3, respectively. Therefore, electromagnetic fields caused by radio waves radiated from the antenna device5do not significantly affect the region of the high-frequency circuit below the lower surface of the second substrate3.

The ground electrodes4and9include openings through which electromagnetic waves from the antenna device4propagate. Additionally, radio waves from the antenna device5may propagate along the exterior of the first substrate2to the region of the high-frequency circuit underneath.

However, in the present preferred embodiment, the plurality of conductive connecting members8are spaced along the frame shaped member11. At the same time, since the plurality of conductive connecting members8are connected to the ground potential, the region where the IC chip16and the high-frequency device17are disposed is electromagnetically shielded. Therefore, it is possible to reduce fluctuations in characteristics caused by propagation of radio waves along the exterior of the first substrate2.

Additionally, since the first substrate2includes the ground electrodes23and24defining ground layers, a circuit region where the IC chip16and the high-frequency device17are provided is reliably electromagnetically shielded by the ground electrodes in the first substrate2, the ground electrodes4and9in the second substrate, and the conductive connecting members8. Thus, fluctuations in characteristics caused by radio waves radiated from the antenna device5are reliably prevented, and, at the same time, it is possible to achieve stable and outstanding reception and transmission performance.

Moreover, in the present preferred embodiment, creating the gap A makes it possible to reduce the effects of radio waves from the antenna device5on the high-frequency circuit.

The permittivity of the second substrate3made of synthetic resin is less than that of the first substrate2made of dielectric material. Since the second substrate3having a lower permittivity includes wiring which electrically connects the antenna device5to the high-frequency circuit, the resonance frequency associated with a wavelength shortening effect determined by the permittivity increases. This prevents degradation in characteristics of the high-frequency module1. That is, since the resonance associated with the wavelength shortening effect occurs at frequencies greater than those used in the high-frequency module1, it is possible to prevent the resonance from degrading the characteristics of the high-frequency module1.

Additionally, since the coplanar line6connected to the antenna device5is surrounded by the ground electrode4and is planar in shape, very few radio waves are radiated from the coplanar line6. Thus, it is possible to prevent the electromagnetic waves from degrading the characteristics of the high-frequency module1. The transmission line connected to the antenna device5is not limited to the coplanar line6.

Although the plurality of conductive connecting members8and the signal terminals12are embedded in the frame shaped member11in the present preferred embodiment, various modifications can be made to the arrangement of the conductive connecting members8and signal terminals12.

FIG. 7AtoFIG. 7Care schematic plan views each illustrating a modified arrangement of the signal terminals and the conductive connecting members connected to the ground potential in the frame shaped member11. Referring toFIG. 7A, conductive connecting members8A and8B connected to the ground potential are disposed at a pair of opposite corners of the rectangular frame shaped member11. The RF terminal12A defining a signal terminal is embedded at one of the two remaining corners, while the bias terminal12B defining a signal terminal is embedded at the other of the two remaining corners. At the same time, the plurality of conductive connecting members8are spaced along each side of the frame shaped member11.

Referring toFIG. 7B, the RF terminal12A is disposed at one of the four corners of the frame shaped member11, while the conductive connecting members8A and8B connected to the ground potential are disposed on both sides of the RF terminal12A. At the same time, a bias terminal12C defining a signal terminal is disposed adjacent to the RF terminal12A with the conductive connecting member8A interposed therebetween, while a bias terminal12D defining a signal terminal is disposed adjacent to the RF terminal12A with the conductive connecting member8B interposed therebetween. Additionally, the conductive connecting members8are embedded in the remaining portion of the frame shaped member11. Thus, in the structure illustrated inFIG. 7B, the signal terminals are disposed at one corner of the frame shaped member.

Referring toFIG. 7C, the RF terminal12A defining a signal terminal is disposed on one side and near one corner of the frame shaped member11, while the conductive connecting members8A and8B connected to the ground potential are disposed on both sides of the RF terminal12A. At the same time, the bias terminal12B is disposed adjacent to the RF terminal12A with the conductive connecting member8A interposed therebetween, while the bias terminal12C is disposed adjacent to the RF terminal12A with the conductive connecting member8B interposed therebetween. Additionally, the conductive connecting members8are embedded in the remaining portion of the frame shaped member11. That is, in the structure illustrated inFIG. 7C, a plurality of signal terminals are disposed on one side of the rectangular frame shaped member11. Some of the plurality of conductive connecting members8may be connected to the ground potential.

As illustrated inFIG. 7AtoFIG. 7C, various modifications can be made to the arrangement of the plurality of signal terminals and conductive connecting members in the frame shaped member11. However, as illustrated inFIG. 7AtoFIG. 7C, it is preferable that a conductive connecting member8connected to the ground potential be interposed between an RF terminal and a bias terminal so that interference between a signal passing through the bias terminal and a signal passing through the RF terminal can be suppressed.

In other words, it is preferable that conductive connecting members connected to the ground potential be disposed around signal terminals so that the signal terminals through which different signals pass are not immediately adjacent to each other.

In the present preferred embodiment, the conductive connecting members embedded in the frame shaped member11preferably have a substantially rectangular columnar shape. However, as illustrated in the schematic partially cutaway plan view ofFIG. 8, substantially circular columnar conductive connecting members31may be embedded in the frame shaped member11. In other words, the conductive connecting members may have either a substantially rectangular or a substantially circular columnar shape. Likewise, the signal terminals may have a substantially circular columnar shape.

Although the plurality of conductive connecting members8and the signal terminals12are embedded in the frame shaped member11in the preferred embodiments described above, signal terminals may be separately provided outside the frame shaped member11.

The plurality of conductive connecting members8are embedded in the frame shaped member11in the preferred embodiments described above. However, as illustrated in the perspective view ofFIG. 9, a plurality of conductive connecting members32may be vertically disposed on the upper surface2aof the first substrate2. In this case, as illustrated inFIG. 10, each conductive connecting member32is connected to an electrode land on the upper surface2aof the first substrate2with conductive joining material. Alternatively, the conductive connecting members32may be configured to protrude from one principal surface of the first substrate. That is, the conductive connecting members32may be formed by stacking, on one principal surface of the first substrate, ceramic green sheets that are not sintered at a firing temperature of the first substrate and have conductive components at locations where conductive connecting members are to be formed, firing the stacked ceramic green sheets at the firing temperature of the first substrate, and removing the unsintered ceramic green sheets. In other words, the conductive connecting members32may be made of sintered metal prepared by co-sintering with the first substrate. The exterior of the conductive connecting members32may be coated with synthetic resin. The conductive connecting members32may be continuously coated in a frame shaped manner, or the plurality of conductive connecting members8may be individually coated with a resin-coating layer33.

In the preferred embodiment illustrated inFIGS. 1A and 1B, a planar dielectric substrate is provided as the first substrate2. Alternatively, as illustrated inFIG. 11, a first substrate41having a recessed portion41ain an upper surface thereof may be provided. The recessed portion41ais provided in the upper surface defining a first principal surface of the first substrate41. The recessed portion41ais surrounded by a frame-shaped step portion41b. A plurality of conductive connecting members8and at least one RF terminal12A are embedded in the step portion41b. In other words, the step portion41bhas a structure similar to that of the frame shaped member11of the above-described preferred embodiments.

That is, the first substrate41of the present modification is a combination of the frame shaped member11and the first substrate2, which are made of a dielectric ceramic. The conductive connecting members8are exposed on the upper surface of the step portion41b. The conductive connecting members8connect the upper surface of the first substrate41to the lower surface3bof the second substrate3illustrated inFIGS. 1A and 1B.

That is, when the first principal surface of the first substrate41includes the recessed portion41a, since the recessed portion41ais in the first principal surface, the step portion41bdefines a portion of the first principal surface. Thus, in the present modification, the conductive connecting members8connect the second principal surface of the second substrate and the first principal surface of the first substrate.

Therefore, in preferred embodiments of the present invention, the conductive connecting members8can be provided in the first substrate41as long as they connect the first principal surface of the first substrate and the second principal surface of the second substrate.