JPH0435106A - Electrode lead connection structure of ultra thin piezoelectric resonator - Google Patents

Abstract

PURPOSE:To increase the connection strength between an electrode lead end and an external lead at the package side by maximizing a pressurizing force by a wire bonder. CONSTITUTION:A conductor pad 35 connecting to an external lead 32 is arranged on a step difference in a package opposite to a pad 34. While one ridge of an annular surrounding part being an opposite face of the pad 34 is bonded to a package inner bottom face, pads 34, 35 are connected by a wire 33. Then one face of one ridge of an ultra thin piezoelectric raw material plate is used as a bonded part of a bottom face in the package, the pad 34 is formed to the other face and the pad 34 is wire-bonded to the pad 35 provided on a step difference of the package inner wall opposite to the said ridge, then the said bonded part acts effectively to enhance the bonding strength when the pad 34 is pressurized by the bonder head.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to the structure of an electrode lead in a piezoelectric resonator using an ultra-thin plate.

(Prior Art) Piezoelectric devices, especially piezoelectric devices that utilize thickness-shear vibration, have traditionally had lead parts extending from electrodes deposited on both sides of a piezoelectric substrate whose main surface is supported in a substantially vertical posture. The base is sandwiched by conductor clips at the tips of a pair of external lead members that pass through the base in an airtight manner near the edges, and the clamping portions are bonded with a conductive adhesive to mechanically fix the piezoelectric substrate and connect the electrode lead portion and the conductor clip. Alternatively, the piezoelectric substrate may be placed in a flat package with its main surface horizontally, and the electrode leads on both sides of the piezoelectric substrate may be hermetically penetrated through the wall of the package and exposed at appropriate locations inside the package. It was common to adhesively fix the lead terminal with a conductive adhesive.

In the conventional piezoelectric resonator described above, electrode lead parts are arranged on the front and back sides of the piezoelectric substrate, respectively, in order to avoid overlapping of the electrode lead parts. This is to support the piezoelectric resonator on the external lead members and lead terminals in a well-balanced manner, and to facilitate electrical connection of the external lead members and the like to the ends of the front and back electrode plates, respectively.

By the way, in recent years, demands for higher frequencies and higher frequency stability have become stricter in various electronic devices 2 communication devices, but general AT-cut crystal oscillations, which have been widely used as piezoelectric devices (vibration Y-, filters), have become stricter in recent years. Although the plate 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, the limit was about 40 M If z.

As one method to solve this problem, so-called overtone oscillation means is widely used to extract the harmonic components of an AT-cut crystal oscillator to obtain the odd-numbered frequency of the fundamental resonance frequency. It is inconvenient to integrate the oscillation circuit into a semiconductor integrated circuit because it requires a 0-tuned circuit. was there.

On the other hand, the surface acoustic wave resonator, whose oscillation frequency is determined by the electrode finger pitch of the ink digital transducer electrode, has been developed due to advances in photolithography technology.
Although it has become possible to achieve resonance up to about l-1z, 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 problems, a piezoelectric resonator as shown in FIG. 2 (al(b)) has been proposed.

That is, as shown in the same figure, this piezoelectric resonator is made by machining or etching the center part of the =- face of the A'F cut crystal block I4 to form the recessed part 15, and
The thickness of the vibrating part 16 located at the bottom surface of the recessed part 15 is set to about 17 μm, for example, if the fundamental resonance frequency of I OOM 1-17 is to be obtained.

As a result of forming the recessed part 15, a thick rectangular annular surrounding part (rib) I7 supporting the peripheral edge of the ultra-thin plate-like vibrating part 16 is formed on the block surface (surface) on the side of the recessed part 15. 16
Since it is formed integrally with the ultra-thin vibrating section, it is possible to mechanically hold the ultra-thin vibrating section. Therefore, the bottom surface of the concave portion 15 (vibrating portion 1
A conductive film 18 is applied to the entire concave side surface of the block 14, including the surface of the block 14, and an electrode (divided electrode in this figure) 9 is placed on the back surface of the block 14.
By forming I9, a vibrator or filter element having a resonant frequency or center frequency approximately equal to the resonant frequency of the ultra-thin vibrating portion can be obtained.

The piezoelectric resonator as described above is suitable for being sealed in a flat package as shown in FIG. 3(a), for example, as one might imagine from its structure.

That is, the conductive film 21 is attached to the entire bottom surface of the dish-shaped base (package) 20, and both of these are placed in the appropriate positions using L, which is arranged so that the face faces the concave side to which the full-surface electrode 18 of the resonator 14 is attached. Once fixed with conductive adhesive 22, the lead end of one electrode facing the entire surface electrode I8 of the resonator can be connected to the conductor pad 23 exposed in the dish-shaped base 20 with a wire 24.

Needless to say, the conductor film 21 and conductor pad 23 attached to the bottom of the old base 20 pass through the wall of the base in an airtight manner and are connected to the external leads 25 and 26 provided on the outer wall of the base. When wire-bonding the reed end extending from one electrode 19 and the pad 23, there is no need to form a special structure on the base bottom [1] due to the shape of the resonator, so the base can be easily manufactured at low cost. It has the following characteristics.

An ultra-thin piezoelectric resonator having the structure described above is used as a multiplexer.
When applied to a filter element, its electrodes and the electrode lead pattern extending therefrom will be as shown in FIG. 3(b).

That is, split electrodes 6 and 7 are attached to, for example, a flat surface of an ultra-thin piezoelectric element plate, electrode leaves 8 and 9 extending from these are oriented toward both edges of the element plate, and wire bonding pads 27 and There will be 28.

However, the above pads 27 and 28 are packaged 2 respectively.
When trying to connect the external lead connection pads 29 and 30 exposed inside the package with bonding wires, as is clear from the figure, the edge of the piezoelectric element plate where the bonding wires are attached is slightly lifted from the bottom of the package. When the pad is pressurized by the bongoo, the free end portion is elastically deformed toward the inner bottom surface of the package, reducing the pressurizing force. As a result, the connection between the electrode lead part and the wire becomes uncertain.
Accidents such as wires coming off often occurred during production tests, sample vibration, and impact tests.

(Object of the Invention) The present invention has been made in view of the problems expected in the structure and manufacturing of the connecting portion of the electrode lead of the ultra-thin piezoelectric resonator as described above, and is an object of the present invention. An object of the present invention is to provide an electrode lead structure that can improve the connection strength when electrically connecting resonators by wire bonding.

(Summary of the Invention) In order to achieve the above object, in the electrode lead connection structure of the ultra-thin piezoelectric resonator according to the present invention, the electrode lead connection structure of the ultra-thin piezoelectric resonator according to the present invention includes It is characterized in that one edge of the annular surrounding portion is adhered to the inner bottom surface of the package.

(Embodiments of the Invention) The present invention will be described in detail below based on embodiments with reference to the drawings.

FIG. 1 is a cross-sectional view showing a configuration in which a vibrator using an ultra-thin piezoelectric element plate according to the present invention is bonded inside a package. Alternatively, a recess 15 is formed by etching, and an ultra-thin bottom portion of the recess is used as a vibrating portion 16, which is mechanically supported by a thick annular surrounding portion 17 around the vibrating portion 16.

A conductive film is attached to the entire surface of the concave side of the crystal block 14 to form a full surface electrode 18, and a partial electrode 6 is formed on the opposite flat surface.
An electrode lead 31 is formed extending from the partial electrode 6, and the end of the lead 31 is used as a butt 34 for bonding to an external lead 32 with a wire 33. A conductor pad 35 connected to the external lead 32 is arranged on the step inside the package facing the pad 34.

Then, one edge of the annular surrounding portion, which is the opposing surface of the pad 34, is adhered to the inner bottom surface of the package, and then the pad 34, 35
A wire 33 connects between them.

In this way, one surface of the same edge of the ultra-thin piezoelectric element plate is used as an adhesive part with the inner bottom surface of the package, and a pad 34 is formed on the other surface, and this pad 34 is attached to the package facing the edge. Since wire bonding is performed with the pad 35 provided on the step of the inner wall, the pad 34 is bonded with the bonder head.
When applying pressure, the adhesive portion effectively acts to increase the connection strength.

(Effects of the Invention) Since the present invention is constructed as described above, it is possible to maximize the pressure applied by the wire bonder when electrically connecting a piezoelectric element plate and a package containing the same. This has a remarkable effect in increasing the connection strength between the electrode lead end and the external lead on the package side and improving reliability.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing an example of how an ultra-thin piezoelectric element plate to which the electrode lead connection structure according to the present invention is applied is housed in a package, and FIG.
Figures (a) and (b) are a tilted view and an A-A sectional view showing the structure of an ultra-thin piezoelectric resonator to which the present invention is applied, and Figure 3 (a).
) and (b) are side cross-sectional views illustrating a general method of sealing an ultra-thin piezoelectric resonator into a package, and a diagram illustrating a conventional method of configuring electrode leads for a multi-moat filter element when applied to an ultra-thin piezoelectric element plate. FIG. 3 is a plan view for explaining defects. 14... Ultra-thin piezoelectric element plate 16... Vibrating part 17...
Annular surrounding part 6.7... Electrode 8.9.31... Electrode lead part 34.35... Pad patent applicant Toyo Tsushinki Co., Ltd.

Claims (1)

[Claims] A partial electrode is provided on one surface extending from the vibrating portion to the annular surrounding portion of a piezoelectric element plate that integrally comprises an ultra-thin vibrating portion and a thick annular surrounding portion that supports the periphery of the vibrating portion; An ultra-thin piezoelectric resonator characterized in that an electrode lead part and an electrode lead end pad are formed extending to the outer edge, and one edge of the annular surrounding part, which is the opposing surface of the electrode lead end pad, is adhered to the inner bottom surface of the package. Electrode lead connection structure.