JPH04117014A - Packing structure for ultra thin piezoelectric resonator - Google Patents

Abstract

PURPOSE:To fix an ultra thin piezoelectric resonator without use of an adhesives by pressing the four corners of the ultra thin piezoelectric resonator with a fork shaped elastic claw projected from a package inner wall to fix the ultra thin piezoelectric resonator. CONSTITUTION:The resonator is pressed and fixed to a package 8 by using an elastic claw 16 projected from a package inner wall or its inner bottom face. Moreover, an electrode 5 of the resonator 1 facing the package inner bottom face is led to a conductor pad 19 provided to other face of the resonator 1 via a conductor film attached to a recessed part of the resonator end face or an inner face of a throughhole 18 penetrated through a proper part of the resonator to be connected to an outer lead terminal 11 of the package 8. Thus, the resonator 1 and the package 8 are fixed without direct adhesion of an adhesives and the electric connection to the package outer lead 11 is attained.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a packaging structure for an ultra-thin piezoelectric resonator, and in particular, to a packaging structure for an ultra-thin piezoelectric resonator, in particular, the present invention is directed to a packaging structure for an ultra-thin piezoelectric resonator, in which at least the resonator and the package are not directly fixed with a conductive adhesive. Concerning the structure for packaging.

(Prior art) In recent years, demands for higher frequencies and higher frequency stability have become stricter in various electronic devices and communication devices. Although the crystal resonator has extremely excellent temperature-frequency characteristics, its resonant frequency is inversely proportional to the plate thickness, so from the viewpoint of manufacturing technology and mechanical strength, 50MH
The limit was about z.

As a method to solve this problem, so-called overtone oscillation means, which extracts the harmonic components of an AT-cut crystal resonator and obtains a frequency that is an odd multiple of the fundamental resonance frequency, is widely used. Since it requires an LC tuning circuit, it is inconvenient to integrate the oscillation circuit into a semiconductor integrated circuit, and the capacitance ratio is large (and the impedance level becomes high, so oscillation may be difficult).

On the other hand, surface acoustic wave resonators, whose resonant frequency is determined by the electrode finger pitch of the interdigital transducer electrodes, have developed IGH technology due to advances in photolithography technology.
Although it has become possible to achieve resonance up to the order of z, there is a problem in that the temperature-frequency characteristics of the piezoelectric substrate that can be used for this are significantly inferior to that of AT-cut crystal.

In order to solve the above-mentioned problems, conventionally, the center of at least one main surface of a piezoelectric block is recessed by mechanical polishing or etching to make the chain part ultra-thin, and its periphery is integrally formed with a thick annular surrounding part. A resonator using a piezoelectric plate that is supported by a piezoelectric plate and that can maintain the mechanical shape of the ultra-thin vibrating part has been researched.

In addition, as an electrode structure for constructing a resonator using a piezoelectric element plate having a cut-off shape, the inventor of the present invention disclosed in Japanese Patent Application No. 1-52529 that the concave side of the piezoelectric element plate is made the entire surface electrode, and the opposite side thereof is We proposed that partial electrodes and electrode leads extending from them to the edges of the piezoelectric element should be formed on the flat surface of the surface.In this way, there would be no need to use special methods for electrode formation, and this resonator could be packaged in a flat type package. When storing and fixing the resonator, fixing the full electrode side to the conductive film provided on the inner bottom of the package using a conductive adhesive makes it easy to fix the resonator to the package and connect one electrode to the external lead. suggested that it might happen.

However, when we actually prototyped the ultra-thin piezoelectric resonator as described above, we found that the resonator was originally 3 m in planar size.
Since the aim was to realize an ultra-small resonator of approximately m x 3 mm and meet the strict demands for ultra-miniaturization of various electronic devices, one edge of the resonator was bonded to the inner bottom of the flat package with conductive adhesive. When fixing, it is not only difficult to limit the contact resistance, but also the strain caused by the hardening of the adhesive is applied directly to the resonator, causing fluctuations in the resonant frequency before and after packaging, and variations in temperature-frequency characteristics after packaging. It has become clear that an increase in the amount of electricity will inevitably cause a defect.

(Objective of the Invention) The present invention has been made in order to eliminate the above-mentioned packaging-related defects in ultra-thin piezoelectric resonators, without directly bonding the resonator and package with adhesive. It is an object of the present invention to provide a packaging structure that can be fixed and electrically connected to external leads of the package.

(Summary of the Invention) In order to achieve the above object, the resonator packaging structure according to the present invention presses and fixes the resonator to the package using elastic claws protruding from the inner wall or inner bottom surface of the package, and
Regarding the resonator electrode facing the inner bottom of the package,
This is guided to a conductor pad provided on the other side of the resonator through a conductive film attached to the inner surface of a through hole that passes through the resonator at a proper location or to a recess on the end face of the resonator, and is connected to the external lead terminal of the package. Configure it as follows.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

Prior to describing the embodiments, in order to aid understanding of the present invention, the packaging structure of an ultra-thin piezoelectric resonator that has been studied in the past will be briefly explained.

Fifth! ! ! if(a) to (c) are a perspective view, an AA sectional view, and a sectional view showing a packaged state of an ultra-thin piezoelectric resonator to which the present invention is applied, respectively.

In these figures (a) and (b), the symbol l is a piezoelectric block such as a crystal, and its − principal surface is the radial block. The bottom surface of the recess 2 is made into contact with the recess by polishing or etching, and the ultra-thin vibrating section 3 is formed on the bottom surface of the recess 2.
At the same time, the periphery of the front vibrating portion 3 is integrally supported by the annular surrounding portion 4 formed on the outer periphery of the piezoelectric block 1.

A whole surface electrode 5 is formed on the recess 2 side of the piezoelectric element plate having such a shape, and a partial electrode 6 and an electrode lead part 7 extending from this to the end of the element plate are formed on the opposite surface to form an ultra-thin plate piezoelectric resonator. .

The ultra-thin plate piezoelectric resonator as described above is suitable for being housed and fixed with its concave side facing the inner bottom surface of a dish-shaped package, as shown in FIG. 2(c). That is, a dish-shaped package 8 made of sintered ceramics or the like has a conductive film 9 on its inner bottom surface.
A conductor pad 10 is provided on the stepped portion of the inside wall, and these are electrically connected to external leads 11 and 12 which are exposed to the outside by passing through the inside wall of the package in a hermetically sealed manner. is bonded to the inner bottom surface conductor film 9 of the package 8 on the surface of the annular surrounding portion 4 with a conductive adhesive 13, and the end portion of the electrode lead 7 of the partial electrode 6 facing the entire surface electrode 5 and the inner wall of the package. After connecting the conductive pads 10 provided at the steps with bonding wires 14, the piezoelectric resonator is sealed with a lid 15 to complete an ultra-thin piezoelectric resonator as a device.

The ultra-thin piezoelectric resonator having the above-mentioned structure has a built-in resonator element plate that is extremely small, so if one edge of the annular surrounding part is fixed to the inner bottom of the package with a conductive adhesive, the adhesive As mentioned above, the strain caused by hardening is directly applied to the base plate, causing fluctuations in the resonant frequency of the resonator and increased variations in temperature-frequency characteristics.

In order to solve this problem, the ultra-thin piezoelectric resonator according to the present invention basically has a packaging structure as shown in FIGS. 1(a) to 1(d).

That is, the conventional method of directly fixing the ultra-thin piezoelectric resonator 1 to the inner bottom surface of the package 8 using a conductive adhesive was abandoned, and the four corners of the fork-shaped elastic claws 1 protruded from the inner wall of the package 8.
6.16, . . . to be fixed by pressing.

A package equipped with the above-mentioned claws 16, 16, . . . is made by cutting out a plate of an elastic material such as a phosphor blue fI4J plate into a shape protruding from the lead frame 17 by etching or the like, as shown in this figure. If the lead frame 17 is embedded in the inner wall of the package 8 when the package 8 is sintered and formed after the necessary shaping, it will be possible to manufacture the package easily.

Also, as is clear from the figure, the nail mentioned above is 16.16%.
When inserting resonator 1 into package 8 having... It will be understood that at the same time, the claws 1616 return to their original state due to their elasticity and press the four corners of the resonator I.

By the way, when the method of storing and fixing the resonator 1 in the package 8 as described above is used, the electrical connection between the entire surface electrode 5 of the resonator 1 on the side of the recess 2 and the inner bottom conductor film 9 of the package 8 is a simple contact and is stable. There is no hope for continuity.

In order to solve this problem, as shown in FIG.
The entire surface electrode 5 of the resonator is electrically connected to the conductor pad 19 on the opposite surface through the conductor film on the inner surface of the through hole 18, and the conductor pad 19 is connected to another conductor pad 20 provided on the step on the inner wall of the package. The pad 20 may be connected to the external lead 11 via the package inner bottom surface conductor film 9, for example, while connecting with the bonding wire 21.

Although the basic embodiments of the resonator packaging structure according to the present invention have been described above, the present invention is not limited thereto. For example, as shown in FIGS. .16, . . . may be made to stand up from the inner bottom surface of the package.

In this case, if the claws 16, 16, . It would be convenient to do so.

Incidentally, since the ceramic package housing the filter element requires sufficient case grounding, there is no need to explain that it requires a large-area conductor film as described above.

By the way, as mentioned above, pressing the four corners of the resonator with the claws is very difficult because both the resonator element plate and the claws are extremely small, so machining the claws and aligning the resonator when inserting it into the package are quite difficult. be. In order to solve this problem, the present invention may be modified as shown in FIGS. 3(a) and 3(b).

That is, the claws 22, 22, . The conductive pad 19 forming the land of the through-hole 18 of the resonator is pressed with each claw, and the tip of the claw 22 and the pad 19 are bonded with a conductive adhesive 23.

By doing so, it is possible to ensure the electrical connection between the entire surface electrode 5 of the resonator and the external lead 11 of the package 8, and also eliminate the difficulty of machining the tips of the claws and aligning the engagement positions of the resonator and the claws. It is possible to ensure that the position of the child is fixed within the package.

Note that the method of connecting the resonator concave-side full-surface electrode 5 to the conductor pad on the opposite surface is not limited to through-holes;
For example, as shown in FIGS. 4(a) to 4(c), a recess 24 formed on the end face of the resonator may be used.

That is, an ultra-thin piezoelectric resonator to which the present invention is applied is produced by aligning and forming a large number of element patterns on a piezoelectric wafer at once, as shown in FIG. Since a through hole is formed across the boundary 25, a conductive film is attached to the inner wall of the through hole, and then the desired shape and structure are obtained by cutting the resonator. It is possible to obtain the resonator side end face recess 24.Thus, the resonator recess side full surface electrode 5 and the conductor pad 26 on the opposite surface are electrically connected through such a recess 24, and the pad 26 is connected to the claw 16 or 22 and fixing with a conductive adhesive 23, it is possible to securely fix the resonator facing the package and electrically connect the entire surface electrode to the package external lead 1.

In addition, in this figure (b), when the piezoelectric element to be housed is a vibrator, the package internal bottom conductor film 9 is not necessarily necessary, so the entire surface electrode 5 of the vibrator 1 is connected to the package external lead 11 via the claw 22. This figure (c) shows an example in which the piezoelectric element to be housed is connected to the
In the case of a filter element, the entire surface electrode 5 serves as a ground electrode, so in order to sufficiently ground it, the entire surface electrode 5 is not only connected to the ground terminal 11 via the claw 16, but also connected to the terminal 11 inside the package. The bottom conductor film 9 and the entire surface electrode 5 are brought into contact with each other.

By doing this, almost no stress is applied to the ultra-thin piezoelectric resonator that would change its resonant frequency or affect its temperature-frequency characteristics, and moreover, the resonator's electrodes and external terminals are Sufficient conduction between the two can be ensured.

(Effects of the Invention) Since the present invention is constructed as described above, it is possible to minimize fluctuations in resonance frequency before and after packaging an ultra-thin piezoelectric resonator and variations in temperature-frequency characteristics after packaging. This has a significant effect on improving yield and reliability.

Moreover, these effects more than compensate for the increased cost due to the smaller and more complex package.

[Brief explanation of the drawing]

FIG. 1(a) is a plan view showing a basic embodiment of the packaging structure of an ultra-thin piezoelectric resonator according to the present invention, and FIG. 1(b)
, (c) and (d) are B-B and C-C in (a) of the same figure, respectively.
and DD sectional view, FIG. 2(a) is a partial sectional view showing another embodiment of the present invention, FIG. (a) and (b) are a plan view and an EE sectional view showing a third embodiment of the present invention, respectively. 411(a) to (C) are perspective views and partial sectional views showing still other embodiments of the present invention, and FIGS. 5(a) to (c) are ultra-thin plate piezoelectric resonances to which the present invention is applied, respectively. FIG. 1 is a perspective view showing the basic structure of the child, a sectional view taken along line A-A, and a sectional view showing a conventional packaging method. DESCRIPTION OF SYMBOLS 1... Piezoelectric element plate, 2... Recessed part, 3... Vibrating part,
4... Annular surrounding part, 5... Electrode facing the inner bottom surface of the package (full surface electrode), 8... Flat type package, 16 and 22... Elastic claw 18... Through hole,
19...Conductor pad, 11...Lead terminal, 23...
...Conductive adhesive, 24... Resonator side end face concavity Patent applicant Toyo Tsushinki Co., Ltd.

Claims (3)

[Claims] (1) An ultra-thin piezoelectric resonator is formed by the annular surrounding part of an ultra-thin piezoelectric resonator using a piezoelectric plate that integrally comprises an ultra-thin vibrating part and a thick annular surrounding part that supports the periphery of the vibrating part. By arranging the concave surface of the piezoelectric material plate so as to face the inner bottom surface of the flat package, and pressing the other surface of the piezoelectric material plate with an elastic claw protruding from the inner wall or inner bottom surface of the package, A packaging structure for an ultra-thin piezoelectric resonator characterized by fixing the resonator to the package. (2) The electrode lead on the side facing the inner bottom surface of the package of the resonator is connected to the other surface of the piezoelectric element plate through a through hole penetrating the annular surrounding portion or a recess provided on the end surface on the resonator side. 2. The ultra-thin piezoelectric resonator packaging structure according to claim 1, wherein the ultra-thin piezoelectric resonator is electrically connected to a pad and connected to a lead terminal exposed on an outer wall of the package via the pad. (3) An elastic claw protruding from the inner wall or inner bottom surface of the package is made of a conductor, and is connected to a lead terminal exposed on the outer wall of the package, and a conductor pad provided on the other surface of the piezoelectric plate is connected to the conductor. 3. The packaging structure for an ultra-thin piezoelectric resonator according to claim 1, wherein the ultra-thin piezoelectric resonator is pressed with an elastic claw and is fixed with a conductive adhesive.