Electronic component module and manufacturing method thereof

An electronic component module has a device-side module A and an antenna-side module B. The device-side module A is equipped with a first dielectric substrate 11 that is formed with a first transmission line 11a and a high-frequency device 13 that is mounted on the first dielectric substrate 11 and is connected to the first transmission line 11a. The antenna-side module B is equipped with a second dielectric substrate 12 that is laid on the first dielectric substrate 11 in such a manner that they are arranged in a lamination direction and that is formed with a second transmission line 12a that is electrically connected to the first transmission line 11, and an antenna element 14 that is provided on the second dielectric substrate 12 and electrically connected to the high-frequency device 13 via the second transmission line 12a and the first transmission line 11a.

BACKGROUND OF THE INVENTION

The present invention relates to an electronic component module and its manufacturing method and, more particularly, to a technique that is effective in increasing the bandwidth of an electronic component module.

With a recent tendency of miniaturization and functionality enhancement of electronic apparatus, there is demand for electronic component modules in which a module incorporating electronic components such as high-frequency devices is integral with an antenna element. In such antenna-integrated electronic component modules, it is desirable that, to improve their characteristics, a substrate provided with the antenna element be made of a material having low dielectric constant.

Conventionally, as disclosed in JP-A-9-237867, an antenna-integrated electronic component module was proposed in which an antenna is supplied with power via a slot by utilizing electromagnetic coupling.

However, the slot measures ½ (i.e., λ/2) of a wavelength λ used. Therefore, the physical dimensions of the slot and the module are necessarily dominated by a frequency used. This restricts the degree of freedom of miniaturization of the electronic component module.

Further, because of the use of the λ/2 slot, the width of a signal pass frequency band is restricted by the slot dimensions, which is an obstruction to increase of the bandwidth of the electronic component module.

SUMMARY OF THE INVENTION

In view of the above, an object of the present invention is to provide an antenna-integrated electronic component module that can be miniaturized and increased in bandwidth.

To attain the above object, an electronic component module according to the invention is characterized by comprising a device-side module comprising a first dielectric substrate that is formed with a first transmission line, and a high-frequency device that is mounted on the first dielectric substrate and connected to the first transmission line; and an antenna-side module comprising a second dielectric substrate that is laid on the first dielectric substrate in such a manner that they are arranged in a lamination direction and that is formed with a second transmission line that is electrically connected to the first transmission line, and an antenna element that is provided on the second dielectric substrate and electrically connected to the high-frequency device via the second transmission line and the first transmission line.

A preferred embodiment of the invention is characterized by further comprising a third dielectric substrate that is formed with a through-hole in which the first dielectric substrate is inserted, mounted with a low-frequency functional component, fixed to the second dielectric substrate, and electrically connected to the first dielectric substrate.

An even preferable embodiment of the invention is characterized in that the first dielectric substrate is made of ceramics.

Another even preferable embodiment of the invention is characterized in that the first dielectric substrate is made of LTCC.

Another even preferable embodiment of the invention is characterized in that the second dielectric substrate is made of a resin.

Still another even preferable embodiment of the invention is characterized in that the first dielectric substrate is formed with a cavity and the high-frequency device is mounted in the cavity.

Another even preferable embodiment of the invention is characterized in that the first dielectric substrate is provided with shielding means that surrounds the high-frequency device and thereby shields it electromagnetically.

Another even preferable embodiment of the invention is characterized in that the shielding means electromagnetically shields a plurality of high-frequency devices individually.

Yet another even preferable embodiment of the invention is characterized in that the shielding means comprises a shield layer that is formed in the first dielectric substrate and a lid member that seals the high-frequency devices.

A further even preferable embodiment of the invention is characterized in that the first dielectric substrate and the second dielectric substrate are laminated on each other.

To attain the above object, a manufacturing method of an electronic component module according to the invention is characterized by comprising the steps of forming a device-side module by mounting a high-frequency device on a first dielectric substrate in such a manner that the high-frequency device is connected to a first transmission line; forming an antenna-side module by providing an antenna element on a second dielectric substrate in such a manner that the antenna element is connected to a second transmission line; and joining the first dielectric substrate and the second dielectric substrate to each other in a lamination direction and thereby electrically connecting the first transmission line and the second transmission line to each other.

A preferred embodiment of the invention is characterized in that the joining of the first dielectric substrate and the second dielectric substrate is performed by applying a conductive bonding material to at least one of a portion of the first transmission line that is exposed in a surface, to be joined to the second dielectric substrate, of the first dielectric substrate and a portion of the second transmission line that is exposed in a surface, to be joined to the first dielectric substrate, of the second dielectric substrate; aligning the first transmission line and the second transmission line with each other and laying the first dielectric substrate and the second dielectric substrate on each other; and solidifying the conductive bonding material and thereby fixing the first transmission line and the second transmission line to each other with electrical continuity established between them.

An even preferable embodiment of the invention is characterized in that the conductive bonding material is solder.

Another even preferable embodiment of the invention is characterized in that the conductive bonding material is a conductive resin paste containing a metal. In general, this conductive resin containing a metal is set by applying heat to it.

The invention provides the following advantages.

In the invention, the first transmission line formed in the first dielectric substrate11that is mounted with the high-frequency device and the second transmission line formed in the second dielectric substrate that is provided with the antenna element are directly connected to each other electrically. Therefore, the physical dimensions of the module are not dominated by a frequency used or the signal pass frequency band is not restricted by the dimension of a slot. This makes it possible to miniaturize and increase the bandwidth of an antenna-integrated electronic component module.

Where the third dielectric substrate is provided that is mounted with the low-frequency functional component and formed with the through-hole in which the first dielectric substrate is inserted, the first dielectric substrate can be positioned with respect to the second dielectric substrate by means of the through-hole of the third dielectric substrate.

Where the first dielectric substrate is made of ceramics such as LTCC, the high-frequency device can be mounted on the first dielectric substrate by thermocompression bonding.

Where the second dielectric substrate is made of a resin, the antenna efficiency can be increased.

Where the high-frequency device is mounted in the cavity that is formed in the first dielectric substrate, the height and the loss of the electronic component module can be reduced.

Where the first dielectric substrate is provided with the shielding means that surrounds the high-frequency device and thereby shields it electromagnetically, electromagnetic influences from external electronic apparatus are prevented and hence the operation can be stabilized.

Where the shielding means electromagnetically shields a plurality of high-frequency devices individually, the isolation characteristic between the devices is improved and hence the operating characteristics can be made even more stable.

According to the manufacturing method of an electronic component module in which the device-side module and the antenna-side module are formed separately and then joined to each other, an antenna-integrated electronic component module can be constructed in which the first dielectric substrate and the second dielectric substrate are in such a combination that they cannot be fired simultaneously as in the combination that the first dielectric substrate and the second dielectric substrate are made of ceramics and a resin, respectively.

Where an exposed portion of the first transmission line formed in the first dielectric substrate and an exposed portion of the second transmission line formed in the second dielectric substrate are fixed to each other with a conductive bonding material such as solder, for example, where a solder paste that can be applied to exposed portions of the transmission lines, molten solder extends across only the exposed portions of the first transmission line and the second transmission line having small contact angles. Therefore, the first dielectric substrate and the second dielectric substrate are positioned correctly. The joining of the first transmission line and the second transmission line, which requires fine alignment, can be performed correctly.

The best mode for carrying out the invention will be hereinafter described in detail with reference to the drawings. In the accompanying drawings, the same members are given the same reference symbol. And redundant descriptions will be omitted. The following descriptions will be directed to the best mode for carrying out the invention, and hence the invention is not limited to it.

As shown inFIG. 1, an electronic component module10according to this embodiment is equipped with a first dielectric substrate11that has a lamination structure and is made of a ceramic dielectric such as LTCC (low temperature co-fired ceramics) and a second dielectric substrate12that is made of a resin dielectric such as a fluororesin, a BT resin, a PPE(O) resin, or a graft polymerization resin and is laid on the first dielectric substrate11(i.e., the substrates11and12are arranged in the lamination direction). The first dielectric substrate11and the second dielectric substrate12constitute a device-side module A and an antenna-side module B, respectively.

First transmission lines11aare formed in layers in the first dielectric substrate11, and second transmission lines12aare formed in the second dielectric substrate12. The first transmission lines11aand the second transmission lines12aare composed of a waveguide and a conductor (in a through-hole) and are made of Au, Ag, Cu, W, or the like. As shown in FIG.1, the first transmission lines11aand the second transmission lines12aare electrically connected to each other. High-frequency devices13are mounted on the first dielectric substrate11and connected to the first transmission lines11a,and antenna elements14such as patch antennas are provided on the second dielectric substrate12and connected to the second transmission lines12a.Therefore, the antenna elements14send or receive a signal to or from the high-frequency devices13via the second transmission lines12aand the first transmission lines11athat are connected to each other directly.

The high-frequency devices13are electronic components that are used in, for example, a 25 GHz band that is a sub-millimeter wave band or a 5 GHz band that is a microwave band. The high-frequency devices13are mounted on the first dielectric substrate11by surface mounting by soldering or brazing or flip chip mounting with Au, an Au—Sn alloy, or the like. Examples of the high-frequency device13are a power amplifier, a mixer, a multiplier, a frequency converter, a high-frequency oscillator, and a low-noise power amplifier. However, the high-frequency devices13are not limited to these electronic components. A plurality of antenna elements14are formed in array form to obtain good directivity.

A ground layer11dthat is formed on the first dielectric substrate11and conductive layers11bthat are connected to the ground layer11dand extend in the lamination direction also serve as shield layers (described later).

The material of the first dielectric substrate11and the second dielectric substrate12is not limited to ceramics or a resin and may be another dielectric material. However, the first dielectric substrate11made of ceramics makes it possible to mount the high-frequency devices13by thermocompression bonding at about 400° C. as in the case of Au connection. The first dielectric substrate11need not have a lamination structure. However, the employment of a lamination structure as in this embodiment facilitates formation of a filter functional component etc. within a substrate. The second dielectric substrate12made of a resin having low dielectric constant makes it possible to increase the antenna efficiency. It is desirable that the relative dielectric constants of the first dielectric substrate11and the second dielectric substrate12be about 6 to 45 and about 2 to 5, respectively.

Alternatively, a single, unarrayed antenna element14may be employed, an example of which is a multi-band antenna capable of sending and receiving radio waves of a plurality of frequencies by a single antenna. Further, the antenna element14is not limited to a patch antenna that is employed in this embodiment and may be any of other forms of antenna such as an inverted-F antenna and a slot antenna.

The first dielectric substrate11is equipped with a shielding means for electromagnetically shielding the high-frequency devices13by surrounding those. The shielding means is composed of the above-mentioned shield layers (i.e., the conductive layers11band the ground layer11dthat are formed in or on the first dielectric substrate11) and a lid member15that seals the high-frequency devices13. The lid member15, which is given a shield function in such a manner that, for example, a resin is plated with a metal, electromagnetically seals the high-frequency devices13together with the shield layers. Alternatively, the lid member15itself may be made of a metal so as to be given a shield function. In the illustrated example, the lid member15is formed with a partition15aand electromagnetically seals the high-frequency devices13individually together with the conductive layers11bformed in the first dielectric substrate11. As such, the lid member15prevents even electromagnetic interference between the high-frequency devices13: stable operating characteristics are obtained by an improved isolation characteristic. Alternatively, the partition15amay be omitted in which case only electromagnetic shielding from the outside is attained.

As described above, in the electronic component module10according to this embodiment, the first transmission lines11aformed in the first dielectric substrate11that is mounted with the high-frequency devices13and the second transmission lines12aformed in the second dielectric substrate12that is provided with the antenna elements14are directly connected to each other electrically. Therefore, unlike in the case that the first transmission lines11aand the second transmission lines12aare connected to each other electromagnetically via slots, the physical dimensions of the module are not dominated by a frequency used or the signal pass frequency band is not restricted by the dimension of slots. This makes it possible to miniaturize and increase the bandwidth of the antenna-integrated electronic component module.

Further, since the high-frequency devices13are electromagnetically shielded by the shielding means, electromagnetic influences from external electronic apparatus are prevented and hence the operation can be stabilized. Still further, since the high-frequency devices13are electromagnetically shielded individually, undesirable electromagnetic coupling in the electronic component module is prevented and the isolation characteristic between the devices is improved, whereby the operating characteristics can be made even more stable.

Next, a manufacturing method of the above-configured electronic component module will be described.

First, the high-frequency devices13are mounted on the mounting surface of the first dielectric substrate11so as to be connected to the first transmission lines11a,whereby the device-side module A is formed. And the antenna elements14are provided on the second dielectric substrate12so as to be connected to the second transmission lines12a,whereby the antenna-side module B is formed (seeFIG. 2). Then, the first dielectric substrate11and the second dielectric substrate12are joined to each other in the lamination direction, whereby the first transmission lines11aand the second transmission lines12aare electrically connected to each other.

As a result, the high-frequency devices13and the antenna elements14are connected to each other via the first transmission lines11aand the second transmission lines12athat are directly connected to the high-frequency devices13and the antenna elements14, respectively. Therefore, as described above, the antenna-integrated electronic component module can be miniaturized and increased in bandwidth.

This manufacturing method makes it possible to construct an antenna-integrated electronic component module in which the first dielectric substrate11and the second dielectric substrate12are in such a combination that they cannot be fired simultaneously as in the combination of this embodiment that the first dielectric substrate11and the second dielectric substrate12are made of ceramics and a resin, respectively.

The joining of the first dielectric substrate11and the second dielectric substrate12is performed in the following manner. First, a solder layer as a conductive bonding member is formed on one or both of portions of the first transmission lines11athat are exposed in the surface, to be bonded to the second dielectric substrate12, of the first dielectric substrate11and portions of the second transmission lines12athat are exposed in the surface, to be bonded to the first dielectric substrate11, of the second dielectric substrate12. The solder layer may be in any of paste form, sheet form, ball form, and BGA (ball grid array) form.

Materials other than solder may be used as the conductive bonding member. For example, paste or sheet-like conductive resins containing a metal that are set when heat, light, an electron beam, or moisture is applied to them may be used.

After application of the solder, the first transmission lines11aand the second transmission lines12aare aligned with respect to each other and the first dielectric substrate11and the second dielectric substrate12are laid on each other and heated. As a result, the solder layer is melted and the first transmission lines11aand the second transmission lines12aare joined to each other.

Although molten solder extends across the exposed portions of the first transmission lines11aand the second transmission lines12ahaving small contact angles, it does not extend to the other regions having large contact angles. Therefore, the first dielectric substrate11and the second dielectric substrate12are positioned by the surface tension of the solder in such a manner that the first transmission lines11aand the second transmission lines12aface each other correctly.

Finally, after the positioning, the joined structure is left at ordinary temperature and the solder solidifies: the first dielectric substrate11and the second dielectric substrate12are fixed to each other while being positioned correctly. In this manner, the two substrates11and12are fixed to each other with a correct positional relationship. The joining of the first transmission lines11aand the second transmission lines12a,which requires fine alignment, can be performed correctly.

After the joining of the first dielectric substrate11and the second dielectric substrate12, the lid member15is attached to the first dielectric substrate11to shield the high-frequency devices13electromagnetically (seeFIG. 2). The electronic component module10is thus completed.

The invention is not limited to the above embodiment. For example, as shown inFIG. 3, the lid member15maybe composed of a plate-like lid15band spacers15cas side walls.

As shown inFIG. 4, a configuration is possible in which cavities11bare formed in the first dielectric substrate11and the high-frequency devices13are mounted in the cavities11b.This configuration can reduce the height and the loss of the electronic component module10.

Further, an electronic component module may be constructed as shown inFIG. 5. A third dielectric substrate16that is formed with a through-hole16ain which the first dielectric substrate11mounted with the high-frequency devices13is inserted and that is mounted with low-frequency functional components17. The third dielectric substrate16is fixed to the second dielectric substrate12by screwing, for example, whereby the first dielectric substrate11and the second dielectric substrate12are aligned with each other. The first dielectric substrate11and the third dielectric substrate16are electrically connected to each other via bonded wires, gold ribbons, a cable and connectors, or the like.

Examples of the low-frequency functional components are a control circuit, a computing circuit, and a signal processing circuit. However, the low-frequency functional components are not limited to these electronic components.

An inexpensive electronic component module can be constructed by using, as the third dielectric substrate16, a common resin substrate such as a glass epoxy resin substrate.