JPH05235689A - High frequency device - Google Patents

Abstract

PURPOSE:To attain the miniaturization and light weight of a high frequency device by using a surface acoustic filter in a bare chip state. CONSTITUTION:The high frequency device is formed in such a way that a semiconductor device 3, a general electronic component 4, and the surface acoustic wave(SAW) filter 10 set in the bare chip state are packaged on the surface of a wiring circuit board 1 in which a wiring circuit 2 consisting of a wiring conductor and an electrode for component mounting is provided, and a high frequency module provided with a lead terminal to be packaged on a printed circuit board is sealed with a metallic case 7. In other words, electrode pads 2a, 2b for the mounting of the SAW filter 10 set in the bare chip state in the prescribed position of the board 1 that is the base substance of the high frequency device are formed. and also, a through hole 2c is formed as needed. Thereby, it is possible to make the circuit 2 of the SAW filter packaging part of the board 1 into high density, and also, to reduce the height of the module, and to miniaturize the whole device including the case 7, and thereby, the miniaturization and light weight of the high frequency device can be attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency device used for communication equipment and the like, and more specifically to a small and lightweight high frequency device having a surface acoustic wave filter (hereinafter sometimes abbreviated as SAW filter) mounted thereon. The present invention relates to a structure that can be realized.

[0002]

2. Description of the Related Art A mobile communication terminal device represented by a car telephone and a mobile telephone mainly focuses on high integration of a semiconductor IC, and has a high frequency device such as a voltage control oscillator (VCO), a high frequency amplifier, a small size, By mounting general electronic components such as surface mount resistors and capacitors and electronic components such as filters and devices on a high-density printed wiring board, downsizing and weight reduction have been realized.

These mobile communication terminal devices will be used in the future.
It is expected that the size and weight will be further improved while further improving the functions, and for that purpose, further miniaturization and higher performance of the electronic parts and devices used are indispensable elements.

FIG. 5 shows a general structural sectional view of a conventional high frequency device, in which a wiring circuit 2 including conductor wiring paths and electrodes for mounting components is provided on the surface of a wiring circuit board 1.
And a semiconductor device 3, a resistor,
A general electronic component 4 such as a capacitor and a filter 5 such as a SAW filter are mounted.

Further, the printed circuit board 1 is provided with lead terminals 6 for mounting the printed circuit board, and further, for the purpose of ensuring reliability by shielding and environmental protection,
The metal case 7 is covered.

The printed circuit board 1 which is the base of the high frequency device includes organic type such as paper / phenol, glass / epoxy and the like, and ceramic type. Recently, in order to realize reduction in size and weight, The tendency of multi-layering is becoming stronger.

[0007]

As described above, in a high frequency device having a filter mounted thereon, an LC filter, a dielectric filter or a SAW filter is appropriately selected as a filter to be used. The performance and shape of the filter are in inverse proportion to each other, and the higher the performance of the filter, the larger the shape and size, which hinders reduction in size and weight of the device. On the contrary, downsizing of the filter due to the limitation of the device size compels the device performance due to insufficient filter characteristics.

This relationship is no exception in the SAW filter which has been widely used recently for downsizing of equipment. In particular, the SAW filter is a so-called can-sealing package type S in which a device is sealed in a metal case.
Since it is used as an AW filter, it has been a major obstacle to the realization of smaller and lighter equipment.

Therefore, the object of the present invention is to provide a high-frequency device which can be reduced in size and weight by using the SAW filter in a bare chip state without using a can sealed package type as the SAW filter. I am trying.

[0010]

In order to achieve the above object, a high frequency device of the present invention is characterized in that a surface acoustic wave filter is bonded and mounted in a bare chip state on at least one surface of a printed circuit board. And, in particular,
It is characterized in that the printed circuit board is made of a low-temperature multilayer ceramic system in which a highly conductive metal essential for reducing loss of a high frequency device can be used as a wiring material, and has a built-in filter function in a circuit. ..

Further, in the high frequency device of the present invention, at least one cavity is formed on at least one surface of the low temperature multilayer ceramic wiring circuit board, and a surface acoustic wave filter in a bare chip state is embedded in the cavity.
It includes those characterized by being mounted by bonding.

[0012]

[Operation] By mounting the SAW filter in a bare chip state as described above, it is possible to reduce the size and weight of the high-frequency device as compared with the case of mounting the conventional can-sealed package type.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to the embodiments shown in the drawings. The same elements as those of the conventional example shown in FIG. 5 are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 shows a first embodiment of a high-frequency device according to the present invention. This high-frequency device has a surface of a wiring circuit board 1 provided with a wiring circuit 2 composed of wiring conductors and electrodes for mounting components. A semiconductor device 3, general electronic components 4, 4, such as resistors and capacitors, and a SAW filter 10 in a bare chip state by bonding, and a lead terminal 6 for mounting the SAW filter 10 on a printed wiring circuit board. The module is sealed with a metal case 7.

That is, the electrode pads 2a and 2b for mounting the SAW filter 10 in the bare chip state are formed at predetermined positions of the printed circuit board 1 which is the base of the high frequency device, and the through holes 2c are formed if necessary. Form. Mounting the SAW filter 10 in the bare chip state
It can be performed by general bonding, and either wire bonding or flip chip bonding may be used.

The high frequency circuit module having the SAW filter 10 in the bare chip state as described above is
The side of the filter 10 is sealed with a metal case 7, and if necessary, the case 7 is filled with an inert gas such as nitrogen gas or argon gas to ensure environmental reliability.

By mounting the SAW filter 10 in a bare chip state on the surface of the printed circuit board 1 as described above, the wiring circuit 2 in the SAW filter mounting portion of the printed circuit board 1 can be made high in density and the module height can be increased. Since the overall size including the metal case 7 can be reduced,
The shielded high frequency device can be made smaller and lighter.

FIG. 2 shows a second embodiment of the present invention. As a printed circuit board which is a base of a high frequency device,
The ceramic multilayer substrate 20 is used. The ceramic multilayer substrate 20 is provided with a predetermined conductive path 21 for each layer and a via hole 22 for interconnecting each layer, and is, for example, a low temperature type ceramic multilayer that can be fired at a temperature of 850 ° C. to 1000 ° C. The substrate is used.

As a multi-layering method, ceramic green sheets having predetermined conductive paths for each layer and via holes for interconnecting each layer are sequentially laminated, thermocompression-bonded, and simultaneously fired to form. Alternatively, a ceramic green board having a via hole for connecting to a lower conductor is attached to a ceramic wiring substrate having a wiring path formed in advance on a core, and after firing, an upper conductor is printed to form a multilayer structure, or Any method may be used, such as a method in which insulating glass is printed and fired, and a conductor path is formed on the insulating glass in order to form a multilayer structure.

In this embodiment, the ceramic multilayer substrate 20 having a built-in filter function is used in the above-described method, the semiconductor device 3, the general electronic parts 4 and 4 such as resistors and capacitors, and the SAW filter in a bare chip state. The high frequency circuit module in which 10 is mounted and the lead terminals 6 are provided is sealed with a metal case 7 to form a high frequency device.

FIG. 3 shows a third embodiment of the present invention, in which one surface of a ceramic multilayer substrate 20 similar to the above is provided with SA
A cavity 30 for mounting a W filter is provided, and the SAW filter 10 is embedded and mounted in the cavity 30. Since the other configurations are the same as those in FIG. 2, the same elements are designated by the same reference numerals and detailed description thereof will be omitted.

FIG. 4 shows a fourth embodiment of the present invention. In the high frequency device shown in the third embodiment, a metal case 7 covering substantially the entire high frequency circuit module is provided.
Instead, a metal cap 31 is provided to cover only the opening of the cavity 30 in which the SAW filter 10 in the bare chip state is embedded and mounted.

As described above, the SAW filter 10 in a bare chip state is mounted by bonding in the cavity 30 provided on one surface of the ceramic multilayer substrate 20, and
By forming the high frequency device by covering only the opening of the cavity 30 with the metal cap 31, the size and weight of the high frequency device can be further reduced.

The circuit formed on the substrate and the components to be mounted can be designed appropriately according to the purpose of the high frequency device, and the present invention can be applied to high frequency devices having various circuit configurations. ..

[0025]

As described above, in the high frequency device of the present invention, since the surface acoustic wave filter is bonded and mounted on the printed circuit board in a bare chip state, the size and weight can be significantly reduced as compared with the conventional product. In addition, it can contribute to the miniaturization and weight reduction of mobile communication terminal devices and the promotion of high functionality.

[Brief description of drawings]

FIG. 1 is a structural cross-sectional view showing a first embodiment of a high frequency device of the present invention.

FIG. 2 is a structural sectional view showing a second embodiment of the same.

FIG. 3 is a structural sectional view showing a third embodiment of the same.

FIG. 4 is a structural sectional view showing a fourth embodiment of the same.

FIG. 5 is a structural cross-sectional view showing an example of a conventional high frequency device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wiring circuit board 2 ... Wiring circuit 3 ... Semiconductor device 4 ... General electronic component 6 ... Lead terminal 7 ... Metal case 10 ... Bare-chip surface acoustic wave (SAW) filter 20 ... Ceramic multilayer substrate 21 ... Conductive path 2
2 ... Via hole 30 ... Cavity 31 ... Metal cap

Claims (3)

[Claims] 1. A high-frequency device comprising a surface acoustic wave filter bonded and mounted in a bare chip state on at least one surface of a printed circuit board. 2. The high frequency device according to claim 1, wherein the printed circuit board is made of a low-temperature multilayer ceramic system and has a filter function built in in a circuit manner. 3. A low-temperature multilayer ceramic printed circuit board having at least one cavity formed on at least one surface thereof, and a surface acoustic wave filter in a bare chip state being embedded and bonded in the cavity. High frequency device.