JP2005130071A - Package structure of piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric device capable of reducing its size even when chip parts for matching circuits or the like are loaded on the piezoelectric device and having high electric characteristics. <P>SOLUTION: In an MCF 19, a piezoelectric substrate 2 is adhesively fixed by applying conductive adhesives 7 to prescribed pads 21 formed on the inner bottom of a ceramic package 20, two prescribed recessed parts 23a, 23b are formed on the outer bottom of the ceramic package 20, chip parts L11, C12 constituting an input side matching circuit for an MCF element 10 are loaded on a pad 24 formed in the recessed part 23a, and chip parts L13, C14 constituting an output side matching circuit for the MCF element 10 are loaded on a pad 24 formed in the recessed part 23b. Then side metalized parts 25a, 25b are respectively formed on the whole side walls of the two recessed parts 23a, 23b and a solid earth pattern 26 of a prescribed shape is formed on the outer bottom of the MCF 19 to connect both the recessed parts 23a, 23b. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a package structure of a piezoelectric device, and more particularly to a composite type piezoelectric device having a configuration in which a chip component for a matching circuit is added to the input / output of an MCF in order to reduce the termination impedance in an MCF (monolithic crystal filter). It relates to the package structure.

Due to the rapid progress in price reduction and miniaturization accompanying the widespread use of mobile communication devices such as cellular phones, devices used in these communication devices are rapidly becoming thinner, and SMD type devices that do not use lead terminals are used. The adoption of electronic devices has become mainstream.
Therefore, in the present invention, the package structure will be described below using MCF as an example. The MCF has an electrode pair divided into two on a single quartz substrate, combines one vibration mode and the other vibration mode, and produces a desired filter characteristic by causing so-called acoustic coupling. It is.

  FIG. 7 shows a first external structure example of a conventional MCF. Fig.7 (a) is a top view of the state which has not covered the cover, (b) is front sectional drawing. As shown in FIG. 7, the MCF 1 according to this external example has two excitation electrodes 3a and 3b on one side of the piezoelectric substrate 2 and a common electrode 4 on the other side. After applying and fixing a conductive adhesive 7 to a predetermined pad 6 provided on the inner bottom surface of the ceramic package 5, the opening of the ceramic package 5 is sealed with a lid 8. An external connection pad 9 is provided.

  On the other hand, when the MCF is used, it may be necessary to reduce the termination impedance of the MCF, and when such a request is made, predetermined means are taken to reduce the input / output impedance of the MCF. In order to reduce the input / output impedance of the MCF, it can be easily realized by increasing the area of the excitation electrode. In this case, however, the spurious level is deteriorated and the size of the piezoelectric substrate is increased in order to increase the area of the excitation electrode. Needs to be increased, which hinders the miniaturization of the MCF.

Therefore, in such a case, it is effective to design the input / output impedance of the MCF as high as possible and add a matching circuit to the input / output end of the MCF to reduce the apparent input / output impedance. In this case, since the number of parts of the MCF increases, it is necessary to devise the package structure of the MCF. However, as disclosed in Japanese Patent Laid-Open No. 10-322129, one or more are provided on the outer bottom surface of the ceramic package. There is known a method of forming a predetermined recess portion and mounting chip components of L (inductance element) and C (capacitance element) constituting a matching circuit for external connection in the recess portion.

  FIG. 8 shows a configuration diagram of an example of a matching circuit added to the MCF, in which L11 and C12 are added as matching circuits to the input end of the MCF element 10, and as a matching circuit at the output end of the MCF element 10. In this configuration, L13 and C14 are added. Since the design method of the matching circuit is well known, the description is omitted.

  FIG. 9 is a second external structure example of a conventional MCF. FIG. 9A is a front sectional view, and FIG. 9B is a bottom view. As shown in FIG. 9, the MCF 15 in the second external structure example includes two recesses 17 a and 17 b on the outer bottom surface of the ceramic package 16 in addition to the first external structure example, and a pad provided in the recess 17 a. The chip parts L11 and C12 constituting the matching circuit corresponding to the input of the MCF element 10 are mounted on 18a, and the matching circuit corresponding to the output of the MCF element 10 is formed on the pad 18b provided in the recess 17b. Chip components L13 and C14 are mounted. By adopting such a mounting method, it is possible to mount a chip component for a matching circuit that needs to be newly added without increasing the package size.

Japanese Patent Laid-Open No. 10-322129 Japanese Patent Laid-Open No. 11-195852 JP 2002-232262 A

  However, in the conventional MCF, as shown in the second external structure example, two recesses are formed on the outer bottom surface of the ceramic package, and the L and C chip parts for the matching circuit are respectively connected to the recesses on the input side and the output side. When mounted in the recess, the L on the input side and the L on the output side are coupled and the input signal to the MCF leaks to the output or the output signal leaks to the input. May lead to deterioration.

Further, in the MCF corresponding to the high frequency, as disclosed in Japanese Patent Laid-Open No. 11-195852, when the MCF is mounted on the printed wiring board, the characteristics equivalent to the filter characteristics in the case of the MCF alone before mounting. May not be obtained. This is caused by the influence of the ground potential of the MCF and the ground potential of the printed wiring board, which has a problem in the method of forming the ground pattern and causes noise through other components mounted on the printed wiring board. This is because MCF is induced by MCF.
The present invention has been made to solve the above-described problems. When a chip component for a matching circuit or the like is mounted on a piezoelectric device, the piezoelectric device is miniaturized and has good electrical characteristics. An object is to provide a piezoelectric device.

In order to achieve the above object, the package structure of the piezoelectric device according to the present invention has the following configuration.
The invention according to claim 1 is a structure in which a piezoelectric resonant element is bonded and fixed to an inner bottom portion of a package and hermetically sealed with a lid. The package has a plurality of concave portions formed on an outer bottom surface, and the concave portions are provided with the concave portions. In a piezoelectric device having a structure in which a chip component for external attachment of a piezoelectric resonance element is mounted, side metallization is applied to the entire side wall of the recess, and the side metallization is connected to a ground terminal of an external connection pad.

According to a second aspect of the present invention, the piezoelectric resonant element is an MCF element, and the external chip component is an inductance element and a capacitive element that constitute an MCF matching circuit.

According to a third aspect of the present invention, a solid earth pattern is formed in an area of the external bottom surface of the package according to the first aspect except for the external connection pads provided on the external bottom surface, and the side metallization and the external connection pads are formed. Configure to connect to the ground terminal.

According to a fourth aspect of the present invention, a ground pattern is formed with a predetermined width so as to surround the plurality of recesses, and the ground pattern is connected to the side metallization and the ground terminal of the external connection pad.

The invention according to claim 5 forms two ground patterns independently with a predetermined width so as to surround the periphery of each recess by forming two of the recesses, and connects to the corresponding side metallization, respectively. The two ground patterns are connected to two ground terminals provided on the external connection pads, respectively.

  According to the first and second aspects of the present invention, when a chip component for external connection necessary for constituting the MCF is mounted on the recess provided on the outer bottom surface of the ceramic package, side metallization is formed on the entire side wall of the recess. Since this is connected to the ground pattern, it is possible to prevent electrical coupling between the external connection chip part on the input side of the MCF and the external connection chip part on the output side, which is remarkable in improving the performance of the MCF. Demonstrate the effect.

According to the third to fifth aspects of the present invention, since the solid ground pattern or the ground pattern is provided on the outer bottom surface of the ceramic package, when the MCF is mounted on the printed circuit board, the MCF from the electrical component mounted on the printed circuit board is used. It is possible to eliminate the influence on the above, and exhibit a remarkable effect when using the MCF.

  In the present invention, when the concave portion is formed on the outer bottom surface of the ceramic package and the input / output matching circuit L and C chip components are mounted in the corresponding concave portions, the L on the input side and the L on the output side are Side metallization is formed on the entire side wall of the recess so as not to cause coupling, and connected to the ground terminal of the external connection terminal, and a ground pattern having a predetermined shape is formed on the external bottom surface of the MCF so that a shielding effect can be obtained. The structure was

  FIG. 1 is an external structure showing a first embodiment of the MCF according to the present invention. Referring to FIG. 1, the MCF 19 according to the present embodiment has two excitation electrodes 3a and 3b on one side of the piezoelectric substrate 2 and a common electrode 4 on the other side. After the conductive adhesive 7 is applied and fixed to a predetermined pad 21 provided on the inner bottom surface of the ceramic package 20, the opening of the ceramic package 20 is sealed with a lid 8. An external connection pad 22 is provided.

Two predetermined recesses 23a and 23b are formed on the outer bottom surface of the ceramic package 20, and the pads 24 provided in the recess 23a have chip parts L11 and C12 that constitute a matching circuit corresponding to the input of the MCF element 10. And a pad 24 provided in the recess 23b is similarly mounted with chip parts L13 and C14 constituting a matching circuit corresponding to the output of the MCF element 10.

In this embodiment, as shown in the enlarged view of the recess 23a, side metallization 25a, 25b is formed on the entire side wall of the recess in each of the two recesses 23a, 23b, and a predetermined shape is formed on the outer bottom surface of the MCF 19. The solid earth pattern 26 is formed to connect the two. An enlarged view (a) of the recess 23a shows a front sectional view, and (b) shows a bottom view. In FIG. 6A, a side metallization 27, which is a part of the side metallization 25a, mainly prevents coupling between inductance elements of chip components mounted in the recesses 23a and 23b. The side metallization 28 and the solid earth pattern 26, which are the parts, mainly prevent the coupling between the inductance element mounted on the MCF 19 and the inductance element mounted on the printed wiring board when the MCF 19 is mounted on the printed wiring board. To do.

Next, details of the ceramic package 20 according to the present invention will be described.
FIG. 2 is a front sectional view showing an embodiment of the ceramic package according to the present invention. As shown in FIG. 2, the ceramic package 20 has a structure in which a first layer 29 and a second layer 30 are laminated, and the pattern connection between the layers is a wiring pattern 31 provided between the layers and the first layer of the ceramic package. 29 and the second layer 30 are connected by a via hole 32 penetrating the external connection pad 22 provided on the outer bottom surface of the ceramic package 20 via a side pattern 33 provided on the side surface of the second layer of the ceramic package. And connect. The solid ground pattern 26 provided on the outer bottom surface of the ceramic package 20 is connected to the side metallizations 25a and 25b provided in the recesses 23a and 23b, and is connected to the ground terminal of the external connection pad 22 provided in the ceramic package 20. .

FIG. 3 is a bottom view of the first embodiment of the MCF according to the present invention. As shown in FIG. 3, in the first embodiment, a solid earth pattern 26 is provided on the outer bottom surface of the ceramic package 20, and is connected to the external connection pads 22a and 22b having the function of the earth terminal, and the recesses 23a and 23b. Are connected to the side metallizations 25a and 25b. On the other hand, the external connection pads 22c and 22d are MCF input and output terminals, respectively.
Next, the influence of the solid earth pattern 26 provided on the outer bottom surface of the ceramic package 20 increases as the MCF is adapted to a high frequency.

  FIG. 4 is a bottom view of the MCF according to the second embodiment of the present invention. As shown in FIG. 4, in the second embodiment, a ground pattern 35 is provided on the outer bottom surface of the ceramic package 34. This ground pattern 35 is formed in a recess 36a with a predetermined width around the outer periphery of the recesses 36a and 36b. , 36b are formed so as to surround each of the enclosed earth patterns. The ground pattern 35 is connected to external connection pads 37a and 37b having a function of a ground terminal, and is connected to side metallizations 38a and 38b provided in the recesses 36a and 36b. On the other hand, the external connection pads 37c and 37d are MCF input and output terminals, respectively.

FIG. 5 is a bottom view of the MCF according to the third embodiment of the present invention. As shown in FIG. 5, in the third embodiment, ground patterns 40a and 40b are provided on the outer bottom surface of the ceramic package 39, and the ground pattern has a recess 41a with a predetermined width around the outer periphery of the recess 41a. A ground pattern 40a formed so as to surround and a ground pattern 40b formed so as to surround the recess 41b with a predetermined width around the outer periphery of the recess 41b are separated into two, and the earth pattern 40a is provided in the recess 41a. In addition to being connected to the side metallized 42a, it is connected to an external connection pad 43a having the function of a ground terminal, and the ground pattern 40b is connected to the side metallized 42b provided in the recess 41b and also has an external connection having the function of the ground terminal It connects with the pad 43b. Accordingly, in the third embodiment, the ground pattern 40a on the input side and the ground pattern 40b on the output side of the MCF are separated. On the other hand, the external connection pads 43c and 43d are MCF input and output terminals, respectively.

Next, an outline of the MCF manufacturing procedure according to the present invention will be described.
FIG. 6 is a flowchart for explaining the manufacturing procedure of the MCF according to the present invention. Explaining FIG. 6, first, after manufacturing an MCF element in which excitation electrodes, pads for external connection and the like are formed on a predetermined piezoelectric substrate with a predetermined shape and film thickness in a separate process (step 1), The MCF element is bonded and fixed to the inner bottom pad of the ceramic package processed into a shape using a conductive adhesive and dried (step 2). Next, the frequency of the MCF element is adjusted. As a method for adjusting the frequency, the excitation electrode formed on the MCF element is made thinner than a predetermined film thickness, a new film is formed on the excitation electrode while checking the frequency, and the frequency is adjusted, and the MCF element There is a method in which the excitation electrode to be formed is made thicker than a predetermined film thickness, and the surface of the excitation electrode is scraped off and the frequency is adjusted while checking the frequency (step 3).

When the frequency adjustment is completed, the ceramic package opening is covered and sealed (step 4), and then the matching circuit input side L, C chip component, output side L are formed in the recess formed on the external bottom surface of the ceramic package. , C chip parts are mounted and sealed (step 5), and the electrical characteristics of the filter are measured and the final product inspection is performed (step 6).

As described above, in the present invention, the side metallization is provided in the recess for mounting the matching circuit chip component and the ground pattern is provided on the bottom surface of the ceramic package, thereby preventing the coupling between the input side and the output side of the MCF. At the same time, it has become possible to eliminate the influence on the MCF from the electrical components mounted on the printed wiring board.
In this embodiment, the MCF has been described. However, the present invention is not limited to this, and any composite piezoelectric device having a structure in which a chip part is mounted by forming a recess on the outer bottom surface of the ceramic package. Adaptable.

It is an external appearance structure which shows the 1st Example of MCF concerning this invention. It is front sectional drawing which shows one Example of the ceramic package concerning this invention. It is a bottom view in the 1st example of MCF concerning the present invention. It is a bottom view in the 2nd example of MCF concerning the present invention. It is a bottom view in the 3rd example of MCF concerning the present invention. It is a flowchart explaining the manufacturing procedure about MCF concerning this invention. It is the example of the 1st external appearance structure of the conventional MCF. It is a block diagram of the example of a matching circuit added to MCF. It is a 2nd external appearance structural example of the conventional MCF.

Explanation of symbols

1 .... MCF, 2 .... piezoelectric substrate,
3a, 3b ... excitation electrode, 4 .... common electrode,
5..Ceramic package, 6..Pad,
7 .... conductive adhesive, 8 .... lid,
9 .... Pad for external connection, 10 .... MFC element,
11 .... Inductance element, 12 .... Capacitance element,
13 .... Inductance element, 14 .... Capacitance element,
15 .... MFC, 16 .... Ceramic package,
17a, 17b ... recess, 18a, 18b ... pad,
19 ・ ・ MCF, 20 ・ ・ Ceramic package,
21. ・ Pad
22, 22a, 22b, 22c, 22d .. pad for external connection,
23a, 23b ... recess, 24 ... pad,
25a, 25b ... side metallization, 26 ... solid earth pattern,
27. ・ Side metallization, 28 ・ ・ Side metallization,
29 ... the first layer, 30 ... the second layer,
31 ... Wiring pattern, 32 ... via hole,
33 ... side pattern 34 ... ceramic package,
35..Earth pattern, 36a, 36b..Recess,
37a, 37b, 37c, 37d .. pad for external connection,
38a, 38b ... side metallization, 39 ... ceramic package,
40a, 40b ... Earth pattern, 41a, 41b ... recess,
42a, 42b .. side metallization,
43a, 43b, 43c, 43d .. pad for external connection

Claims (5)

The piezoelectric resonance element is bonded and fixed to the inner bottom portion of the package and hermetically sealed with a lid. The package has a plurality of recesses on the outer bottom surface, and the recesses are used for external attachment of the piezoelectric resonance element. In a piezoelectric device with a structure with chip components mounted,
A package structure for a piezoelectric device, characterized in that side metallization is applied to the entire side wall of the recess, and the side metallization is connected to a ground terminal of an external connection pad.   2. The package structure of a piezoelectric device according to claim 1, wherein the piezoelectric resonant element is an MCF element, and the external chip component is an inductance element and a capacitive element that constitute an MCF matching circuit.   The external bottom surface of the package according to claim 1, wherein a solid ground pattern is formed in an area excluding the external connection pad provided on the external bottom surface, and connected to the side metallization and the ground terminal of the external connection pad. 3. The package structure of a piezoelectric device according to claim 1, wherein the package structure is a piezoelectric device package.   3. The piezoelectric device according to claim 1, wherein a ground pattern having a predetermined width is formed so as to surround the plurality of recesses, and the ground pattern is connected to a ground terminal of the side metallization and the external connection pad. Package structure. Two recesses are formed, two ground patterns are independently formed with a predetermined width so as to surround the periphery of each recess, and connected to the corresponding side metallization, and the two ground patterns are externally connected. 3. The package structure of a piezoelectric device according to claim 1, wherein the package structure is connected to two ground terminals provided on the pad for use.

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