JP3471187B2 - Surface acoustic wave device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of constructing a surface acoustic wave device.

[0002]

2. Description of the Related Art A surface acoustic wave device using a piezoelectric material is composed of a piezoelectric substrate and a sound-electric conversion electrode formed on the surface thereof. The piezoelectric substrate is made of, for example, crystal, lithium niobate, lithium tantalate, α-aluminum phosphate, piezoelectric ceramic, or the like. The piezoelectric substrate is formed by forming a piezoelectric film, for example, a vapor-deposited film or sputtered film of cadmium sulfide, zinc oxide, aluminum nitride or the like on a predetermined substrate. These surface acoustic wave devices are used in various applications by combining the above-mentioned piezoelectric material with various shapes of acoustic-electric conversion electrodes.

An example of the surface acoustic wave device will be described with reference to the high frequency bandpass filter composed of the lithium niobate substrate shown in FIG. FIG. 2 is an example of a surface acoustic wave device 16 for in-band characteristics. 1A is an element chip for in-passband characteristics, 2 is a sound-electric conversion pattern for in-passband characteristics, 4A is a package,
5A, 5B, 5C and 5D are pads for wire bonding on the chip side, 7A, 7B, 7C and 7D are pads for wire bonding on the package side, 9A, 9B, 9C and 9D are bonding wires, and 11 and 12 are matching The circuit, 15A and 15B, is ground. In-passband characteristic element chip 1 in which in-passband characteristic sound-electric conversion pattern 2 having a small number of comb-shaped electrode pairs is formed
Die-bonding A to one package 4A, and bonding pads 5A, 5B, 5C, 5D for input, output, ground, etc. of element chip 1A for pass band characteristics, and external connection terminals for input, output, ground, etc. of package 4A 7A, 7B, 7C and 7D are connected by bonding wires 9A, 9B, 9C and 9D, the package is sealed with a cap, and the surface acoustic wave device 16 for in-passband characteristics is completed. Similarly, FIG. 3 is an example of the surface acoustic wave device 17 for out-of-band characteristics, 1B is an element chip for out-of-band characteristics,
3 is an out-of-band characteristic sound-electric conversion pattern, 4B is a package, 6
A, 6B, 6C and 6D are pads for wire bonding on the chip side, 8A, 8B, 8C and 8D are pads for wire bonding on the package side, 10A, 10B, 10C and 10D are bonding wires, and 13 and 14 are matching. The circuits, 15C and 15D, are ground. One out-of-band characteristic element chip 1B in which the out-of-band characteristic sound-electric conversion pattern 3 having a large number of comb-shaped electrode pairs is formed.
Bonding pads 6A, 6B, 6C, 6D for input, output, ground, etc. of element chip 1B for characteristics within pass band and external connection terminals 8A, 8B for input, output, ground, etc. of package 4B by die bonding to one package 4B , 8C, 8D are connected by bonding wires 10A, 10B, 10C, 10D, and the package is sealed with a cap to complete the surface acoustic wave device 17 for in-passband characteristics. These two elements are, for example, on the reception side of the radio device, through the matching circuit 11 after the antenna, the device 16 for characteristics within pass band, then the matching circuit 12,
Device 17 for out-of-band characteristics via amplifier and matching circuit 13, matching circuit 14, and ground terminal if necessary
It is configured as a high-frequency bandpass filter by 15A, 15B, 15C and 15D.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
Two elements, a device for in-pass band characteristics and a device for out-of-band characteristics, are required for one high-frequency band-pass filter. The dicing process is performed by cutting out from the piezoelectric substrate on which the element pattern is formed and forming the chip into a package. Die bonding work to fix, work to seal the cap in the package, work to check the device characteristics, etc., and many other parts and materials required for the work, and the defect that the parts and materials are approximately doubled. However, there was a drawback that the mounting work was about doubled.

In general, the element that achieves one frequency characteristic specification is in principle one element,
In a high frequency element such as a surface acoustic wave device, it may be difficult for one element to satisfy the frequency characteristic depending on the frequency characteristic specification. For example, in a high frequency band pass filter using a surface acoustic wave device, there are pass band in-band characteristics and out band characteristics in frequency characteristic specifications. The in-pass band characteristics are more advantageous when the number of pairs of comb electrodes is smaller, and the out-of-band characteristics cannot be achieved unless the number of pairs of comb electrodes is large. As described above, in a high-frequency bandpass filter using a surface acoustic wave device, in order to form a comb-shaped electrode suitable for frequency characteristics with one element, a sufficient frequency characteristic can be obtained by designing with a limited number of electrode pairs. It had the drawback of being difficult to achieve.

The present invention solves these drawbacks by
The purpose is to configure one high-frequency bandpass filter in one package.

[0007]

In order to achieve the above-mentioned object, the present invention forms an in-passband characteristic element pattern and an out-of-band characteristic element pattern in one chip by one high-frequency bandpass filter, It is designed to be assembled and mounted in one package.

[0008]

The structure of the present invention will be described below with reference to an embodiment in which the present invention is applied to a high frequency band pass filter.

An assembled mounting diagram of a high frequency bandpass filter according to an embodiment of the present invention will be described with reference to the conceptual diagram of FIG. The reference numerals used in FIG. 1 are the same as those used in the description of the prior art, and the other symbols 4 are packages.

First, as shown in FIG. 1, on the surface of a lithium niobate substrate 1 having a predetermined plate thickness, the surface of which is mirror-polished, a sound-electricity conversion electrode pattern 2 for in-passband characteristics and an out-of-band characteristic The sound-electric conversion electrode pattern 3 is formed at a position orthogonal to the surface acoustic wave propagation direction 18. In this embodiment, the arrangement of the in-passband characteristic acoustic-electric conversion electrode pattern 2 and the out-of-band characteristic acoustic-electric conversion electrode pattern 3 will be described side by side, but it is clear that the same effect can be obtained in vertical arrangement. For the sound-electric conversion electrodes 2 and 3, a material having a small electric resistance and a light weight, for example, an aluminum or aluminum alloy film formed by a vacuum deposition method is used in order to improve the sound-electric conversion function.

A pair of the in-passband characteristic acoustic-electric conversion electrode pattern 2 and the out-of-band characteristic acoustic-electric conversion electrode pattern 3 formed on the surface of the lithium niobate substrate 1 is made into one chip and cut out by dicing, for example, 8 terminals. Die-bonding to the package 4 having Sonic conversion electrode pattern 2 for in-passband characteristics, S / E conversion electrode pattern 3 for out-of-band characteristics
Input, output, ground bonding pads 5A, 5B, 5C, 5D, 6A, 6B, 6C, 6D and package 4 input, output, ground and other external connection terminals 7A, 7B, 7C, 7
Bonding wires 9A, 9B, 9C, 9 for D, 8A, 8B, 8C, 8D
Connect with D, 10A, 10B, 10C, 10D. The surface acoustic wave device is completed by sealing the package 4 with a cap.

This device is, for example, on the receiving side of a radio device, through a matching circuit 11 next to an antenna, a device 16 for characteristics in pass band, then a matching circuit 12, an amplifier,
The device 17 for out-of-band characteristics, the matching circuit 14, and the ground terminals 15A and 15 as necessary through the matching circuit 13.
B, 15C, and 15D form a high-frequency bandpass filter.

Although the present invention has been specifically described based on the above embodiment, it is obvious that the present invention is not limited to the above embodiment and can be variously modified without departing from the scope of the invention. For example, in the present invention, the substrate may be made of a piezoelectric material such as quartz, lithium tantalate, or zinc oxide. Further, in the above embodiment, the in-passband characteristic device 16 and the out-of-band characteristic device 17 are arranged parallel to the surface acoustic wave propagation direction 18, but as shown in FIG.
Device for in-band characteristics 16 and device for out-of-band characteristics 17
Are arranged on the same straight line with respect to the surface acoustic wave propagation direction 18, it is possible to improve the recovery efficiency of the input signal and reduce the total insertion loss. At this time, the in-passband characteristic device 16 and the out-of-band characteristic device 17, or the plurality of passband in-characteristic devices 16 and the plurality of out-of-band characteristic devices 17 are appropriately arranged in the same substrate to obtain a desired property. Obviously, it is possible to obtain the frequency characteristic of.

[0014]

According to the present invention, when a plurality of elements are formed on the same piezoelectric substrate in the assembly and configuration of the surface acoustic wave device using the sound-electric conversion electrode pattern formed on the piezoelectric substrate, for example, within the pass band. By arranging the device for characteristics and the device for characteristics outside the band on the same straight line in the propagation direction of the surface acoustic wave, the distance between the device for characteristics within pass band and the device for characteristics outside band can be The inter-position between the internal specification element comb-shaped electrode and the out-of-band specification element comb-shaped electrode is set to an integer multiple of [target frequency wavelength / 4] to improve input signal recovery efficiency and reduce overall insertion loss. That is, the surface acoustic wave is a “wave” by utilizing the complicated interference between the in-band specification element comb-shaped electrode and the out-band specification element comb-shaped electrode due to surface wave and surface wave reflection. Within the band Like to reduce the ripple, superior properties than the frequency characteristics which is formed by combining individual elements into a plurality of substrates can be obtained. At the same time, by forming the device for in-band characteristics and the device for out-of-band characteristics on the same chip, the dicing work for cutting out from the piezoelectric substrate on which the element pattern is formed into chips and halving the chips is fixed to the package. A lot of assembly work such as die bonding, cap sealing in the package, device characteristic check work, etc., and it is possible to halve the parts such as package cap in the package. Various surface acoustic wave devices can be manufactured in a short time. In addition, it is possible to avoid a pairing failure such as an unexpected drop in in-band insertion loss that occurs when the individual elements are combined.

Further, the characteristics which are superior to the frequency characteristics, for example, the characteristics such as the reduction of the insertion loss and the reduction of the in-band ripple, which are difficult due to the distance between the devices, are eliminated. Easy to improve.

[Brief description of drawings]

FIG. 1 is an assembly mounting diagram of a high-frequency bandpass filter according to an embodiment of the present invention.

FIG. 2 is an assembly mounting diagram of a device within a pass band of a conventional high frequency band pass filter.

FIG. 3 is an assembly mounting diagram of an out-of-band device of a conventional high-frequency bandpass filter.

FIG. 4 is an assembly mounting diagram of a high-frequency bandpass filter according to an embodiment of the present invention.

[Explanation of symbols]

1: Piezoelectric substrate, for example, lithium niobate substrate, 2: Sonic conversion electrode pattern for in-passband characteristics, 3: Sonic conversion electrode pattern for out-of-band characteristics, 4: Mounting package, 4
A, 4B: Conventional mounting package, 5A, 5B, 5C, 5D, 6
A, 6B, 6C, 6D: Bonding pads for input, output, ground, etc., 7A, 7B, 7C, 7D, 8A, 8B, 8C, 8D: External connection terminals for package input, output, ground, etc., 9A,
9B, 9C, 9D, 10A, 10B, 10C, 10D: Bonding wire, 11, 12, 13, 14: Matching circuit, 15A, 15
B, 15C, 15D: Ground terminal

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H03H 9/64 H03H 3/08 H03H 9/145

Claims (4)

(57) [Claims] 1. A pass band used for a high frequency band pass filter on a substrate having a piezoelectric substrate or a piezoelectric film substrate.
In-characteristic element pattern and out-of-band characteristic element pattern
To form the element pattern for characteristics within the pass band.
Element pattern for out-of-band characteristics by connecting to an external connection terminal
Connected to the corresponding external connection terminal, and connect them to the same board.
Form devices for over-band characteristics and out-of-band characteristics
A surface acoustic wave device having the above structure. 2. The surface acoustic wave device according to claim 1.
The number of comb-shaped electrode pairs of the out-of-band characteristic element pattern is
More than the number of comb-shaped electrode pairs in the element pattern for in-passband characteristics
A surface acoustic wave device characterized in that 3. A surface acoustic wave device as claimed in claim 1 or claim 2 wherein, for the out-of-band characteristic and the pass band characteristic element pattern
A surface acoustic wave device characterized in that an element pattern is formed on the same straight line as a surface acoustic wave propagation direction. 4. A piezoelectric substrate or a piezoelectric film substrate is provided.
Form a metal film containing at least aluminum on the substrate
And the metal film is processed into a comb-shaped electrode pattern
And the piezoelectric film substrate or the piezoelectric film substrate.
Fixing the substrate to be cut out to the package, and
Package external connection terminals and the comb-shaped electrode pattern
Wiring with bonding pad with bonding wire
And a process including a step of sealing with a sealing member
In addition, in order to achieve the frequency characteristic specification, the element for characteristic in the pass band is
The child pattern and the element pattern for out-of-band characteristics are the same.
On the substrate having the piezoelectric substrate or the piezoelectric film substrate
In the formed surface acoustic wave device, in the pass band characteristic element pattern and the out-of-band characteristic element
Element pattern is formed on the same straight line as the surface acoustic wave propagation direction
However, the element pattern for characteristics in the pass band and the out-of-band characteristic
Set the position between the sex element patterns to an integer multiple of the target frequency wavelength.
Or a surface acoustic wave device characterized by being configured to be an integral multiple of 1/4 .