JPH06152307A - Surface mounted piezo-electric vibrator - Google Patents

Abstract

PURPOSE:To provide a surface mounted piezo-electric vibrator excellent in shock resistance. CONSTITUTION:In the surface mounted piezo-electric vibrator having structure forming conductive plating parts 11 on the bottom part of a ceramic base 10 and sticking and fixing a holding fixture base part (not shown in a figure) for conductively holding piezo-electric vibrator chips on short dashes line parts, alloy containing palladium is applied to the plating parts 11 to generate oxide films, so that adhesive force is increased. On the other hand, slits 11a are formed on the plating parts 11 so as to expose a part of ceramic ground and parts including the exposed ground are stuck and fixed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount type piezoelectric vibrator in which a piezoelectric vibrator piece is held in a ceramic package and a package base and a cap are sealed with a low melting point glass seal.

[0002]

2. Description of the Related Art It is widely practiced to seal a piezoelectric vibrator piece made of a crystal or a ceramics piezoelectric body in a package for surface mounting. FIG. 5 is a side view of the surface-mounted piezoelectric vibrator, in which both ends of the piezoelectric vibrator piece 50 are conductively held by the free ends of the pair of inner leads 51, which are holding metal fittings, respectively. The base is adhered and fixed to the bottom of the ceramic base 52 that is the package base. Further, the edge of the ceramic cap 54 is brought into contact with the low-melting glass seal 53, and the glass seal 5
Both are sealed by melting and hardening 3.

The bottom surface of the ceramic base 52 is shown in FIG.
As shown in FIG. 5, a conductive plated portion 55 is formed for connecting the piezoelectric vibrator piece 50 to a circuit component (not shown). The bottom surface of the ceramic base 52 is ensured through the conductive plated portion 55. Fixed to the section.

Usually, the piezoelectric vibrator piece 50 and the free end of the inner lead 51, the base of the inner lead 51 and the conductive plating 55, and the base of the inner lead 51 and the bottom of the ceramic base 52 are fixed to each other by soldering or soldering. Although an organic conductive adhesive is used, in the case of sealing with a low melting point glass as shown in FIG. 5, heating at about 350 to 400 ° C. is required, so that it is more heat resistant than solder bonding. There is no choice but to rely on organic conductive adhesives. Therefore, conventionally, the imide-based heat-resistant conductive adhesive 56 has been often used.

[0005]

As described above, as the heat-resistant conductive adhesive 56 in the case of sealing with a low melting point glass, the conventional
Although an imide-based adhesive is used, when the imide-based adhesive 56 is also heated at 350 to 400 ° C., the resin itself is decomposed and a loss on heating of about 5% occurs. For example, in the case of the most frequently used polyimide adhesive, 1
At 50 ° C, the solvent first escapes, and at 350 ° C, crosslinking proceeds.
Then, the decomposition of the resin begins at 360 ° C. Therefore, 400
When heated at ℃, the adhesive force of the resin becomes small. In particular, when a silver filler is used for imparting conductivity, the silver filler catalytically acts on the polyimide to further lower the decomposition initiation temperature and promote the reduction of the adhesive strength. Therefore, there is a problem that each adhesive fixing part cannot withstand the impact applied when the piezoelectric vibrator is automatically mounted on a circuit board or the like, or the frequency largely drifts due to a change with time of each fixing part.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a surface mount type piezoelectric vibrator having sufficient impact resistance even by sealing with a low melting point glass. is there.

[0007]

Polyimide-based adhesives are the most excellent current heat-resistant conductive adhesives. Therefore, in the present invention, the above object is achieved by adopting an adhesive constitution in which sufficient impact resistance is obtained even if the adhesive force is reduced due to the decomposition of the resin.

Specifically, a conductive plated portion is formed on the bottom surface of the package base, and the base portion of the piezoelectric vibrator piece or a holding metal member for holding the piezoelectric vibrator piece in conduction is bonded to the conductive plated portion. In the surface-mounted piezoelectric vibrator fixed, the conductive plated portion is formed of a metal material having an oxide film formed on its surface, for example, an alloy containing palladium.

In addition, a slit is formed at the adhesive fixing portion of the conductive plated portion to partially expose the bottom surface portion of the package base, and the piezoelectric vibrator piece or the holding member is held on the exposed base member and conductive plated portion. The metal fitting base is adhered and fixed, or a slit is formed in the electrode film of the piezoelectric vibrator piece to expose a part of the surface of the piezoelectric vibrator piece, and the exposed surface of the piezoelectric vibrator piece and the electrode film are attached to the holding metal fitting. It was adhered and fixed to the free end or the conductive plated portion.

In the above structure, the adhesive used for the adhesive fixing is the first heat-resistant conductive adhesive applied to the bonding site and the second heat-resistant conductive adhesive covering the first heat-resistant conductive adhesive. And a heat resistant conductive adhesive, and the second heat resistant conductive adhesive has a higher heat resistance than the first heat resistant conductive adhesive.

[0011]

When the conductive plated portion is formed of an alloy containing palladium, an oxide film is formed on the surface thereof. By bonding and fixing the inner base base or the like on this oxide film, the adhesive force is increased in combination with the condensing force of the adhesive, and the impact resistance is improved.

Further, by forming a slit in the conductive plated portion or the electrode film and adhering and fixing the slit together with the partially exposed surface of the package base or the surface of the piezoelectric vibrator, the adhering area is increased and the impact resistance is improved.

Further, at the time of adhesive fixing, first the first heat resistant conductive adhesive is applied to the bonding site and cured, and then it is covered with the second heat resistant conductive adhesive having high heat resistance.
It is possible to compensate for the decrease in the adhesive strength of the first heat resistant conductive adhesive.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view of a surface mount type piezoelectric vibrator according to an embodiment of the present invention. 10 is a ceramic base which is a package base, 11 is a conductive plated portion, and 12 is a glass seal. The glass seal 12 is the same as the conventional product. The conductive plated portion 11 is formed of a metal material that produces an oxide film on its surface, for example, an alloy of silver and palladium. Then, the base of the inner lead 51 (see FIG. 5) was adhesively fixed on the oxide film formed on the surface of the conductive plated portion 11. As a result, the adhesive force is increased in combination with the condensing force of the adhesive itself, and the impact resistance is remarkably improved as compared with the conventional conductive plated portion using a stable substance such as gold.

In the present embodiment, the conductive plated portion 11 is also used.
A slit 11a was formed in the substrate to expose a part of the bottom surface portion of the ceramic base 10. Then, the base portion of the inner lead 51 was adhesively fixed at a portion surrounded by the broken line in FIG. 1 including the exposed portion. Since the surface of the ceramic has more irregularities than the metal surface, the adhesive area is increased, the adhesive strength is strengthened compared to the conventional one, and the impact resistance is improved. For the same reason, as shown in FIG. 2, the electrode film 2 of the piezoelectric vibrator piece 20 is
1 to form a slit 21a to expose a part of the piezoelectric vibrator piece 20, and to expose the electrode film 21 and the exposed piezoelectric vibrator piece 20.
The surface was adhesively fixed to the free end of the inner lead 51. The slit 11a of the electroconductive plated portion 11 shown in FIG. 1 and the slit 21a of the piezoelectric vibrator piece 20 shown in FIG. 2 are preferably used in combination, but either one can be an effective means for enhancing the impact resistance. .

Next, the heat-resistant conductive adhesive that is adhesively fixed will be described.

FIG. 3A is a diagram showing how the ceramic base and the base of the inner lead 51 are adhesively fixed, and FIG. 3B is a diagram showing how the piezoelectric vibrator piece 20 and the inner lead 51 free end are adhesively fixed. In this embodiment, a polyimide-based adhesive is used as in the conventional case, but aluminum filler is used instead of the conventional silver filler adhesive (first heat-resistant conductive adhesive) (second heat-resistant conductive agent). Adhesive) was also used together. An adhesive containing aluminum as a filler has a resin decomposition initiation temperature of 460 ° C., which is higher than that of silver, so that the adhesive strength can be maintained. However, since the aluminum filler has a large volume resistivity of 1 × 10 ⁶ [Ω · cm], as shown in FIGS. 3 (a) and 3 (b), first, adhesion of a silver filler having higher conductivity is performed. Adhesive while maintaining continuity with agent 31, and then adhesive 3 of aluminum filler
2 was applied and cured. As a result, even if the glass is sealed with a low melting point glass, the decrease in adhesive strength due to heat can be compensated by the second heat-resistant conductive adhesive, and the conventional problems can be solved.

The above is an example in which the piezoelectric vibrator piece 20 elastically held by the inner lead 51 is arranged in the ceramic base 10. However, the present invention is effective even when the piezoelectric vibrator piece 20 is directly adhered and fixed to the ceramic base. It becomes a means.

FIG. 4 is a sectional view of the package of the surface mount type piezoelectric vibrator showing the embodiment, and the electrode films 21 are formed on both sides of the package.
One end of the piezoelectric vibrator piece 20 in which the slit 21a and the slit 21a are formed is bonded and fixed to the supporting portion 41 of the ceramic base 40 as shown in the drawing.

The supporting portion 41 is plated with a conductive material. As described above, a slit is formed in the plated portion to partially expose the ceramic background. Further, as the adhesive 42, a silver filler is applied first, and then an aluminum filler is applied. After the adhesive 42 is cured, the glass base 43 is used to apply the ceramic base 40.
And the ceramic cap 44 are sealed. This allows
It is possible to obtain a surface mount type piezoelectric vibrator having excellent impact resistance. Although FIG. 4 shows an example of so-called one-sided support, the same effect can be obtained in the case of supporting both ends of the piezoelectric vibrator piece 20.

[0022]

As described above, in the present invention, the conductive plated portion for adhering the piezoelectric vibrator piece or the holding metal member is formed of a metal material having an oxide film formed on its surface, for example, an alloy containing palladium. Therefore, there is an effect that the adhesive force by the adhesive is increased as compared with the case of plating with a stable substance such as gold.

In the present invention, a slit is formed in the adhesive fixing portion of the conductive plated portion or the electrode film of the piezoelectric vibrator piece to partially expose the bottom surface of the package base or the piezoelectric vibrator piece surface. Since the adhesive is fixed by including the portion, the adhesive area becomes wider and the adhesive force is increased as compared with the case of only the plated portion or the electrode film.

Further, at the time of bonding and fixing, the first heat resistant conductive adhesive is first applied to the bonding site, and then the surface is covered with the second heat resistant conductive adhesive having high heat resistance.
A decrease in adhesive strength during heating is prevented.

As a result, it is possible to provide a surface-mounted piezoelectric vibrator having sufficient impact resistance even by sealing with a low melting point glass.

[Brief description of drawings]

FIG. 1 is a front view of a surface-mounted piezoelectric vibrator according to an embodiment of the present invention.

FIG. 2 is a front view of a piezoelectric vibrator piece used in this example.

FIG. 3 is an explanatory view of adhesive fixing according to the present embodiment,
(A) shows a bonded state between the base of the inner lead and the ceramic base, and (b) shows a bonded state between the piezoelectric vibrator piece and the free end of the inner lead.

FIG. 4 is a side sectional view of a surface-mounted piezoelectric vibrator according to another embodiment of the present invention.

FIG. 5 is a side view of a conventional surface mount type piezoelectric vibrator sealed with a low melting point glass.

FIG. 6 is a plan view of a ceramic base of a conventional surface mount piezoelectric vibrator.

[Explanation of symbols]

10, 40, 52 ... Ceramic base (package base) 11, 55 ... Conductive plated part 11a ... Slit 20 ... Piezoelectric vibrator piece 21 ... Electrode film 21a ... Slit 31, 32 ... Heat resistant conductive adhesive 51 ... Inner lead Section (holding bracket)

Claims (6)

[Claims] 1. A conductive plated portion is formed on a bottom surface of a package base, and a piezoelectric vibrator piece or a base of a holding metal member for holding the piezoelectric vibrator piece in conduction is adhered and fixed to the conductive plated portion. In the surface mount type piezoelectric vibrator, the conductive plated portion is made of a metal material having an oxide film formed on the surface thereof. 2. The surface-mounted piezoelectric vibrator according to claim 1, wherein the metal material is an alloy containing palladium. 3. A conductive plating portion is formed on a bottom surface portion of a package base, and a piezoelectric vibrator piece or a base portion of a holding metal member for holding the piezoelectric vibrator piece in conduction is adhesively fixed to the conductive plating portion. In the surface mount type piezoelectric vibrator, a slit is formed at the adhesive fixing portion of the conductive plated portion to partially expose the bottom surface of the package base, and the exposed base member and conductive plated portion. A surface mount type piezoelectric vibrator, wherein the piezoelectric vibrator piece or the base of a holding metal is bonded and fixed to the. 4. A conductive plated portion is formed on the bottom surface of the package base, and a piezoelectric vibrator piece or a base of a holding metal member for holding the piezoelectric vibrator piece in conduction is adhered and fixed to the conductive plated portion. In the surface mounted piezoelectric vibrator, a slit is formed in the electrode film of the piezoelectric vibrator piece to expose a part of the surface of the piezoelectric vibrator piece, and the exposed surface of the piezoelectric vibrator piece and the electrode film are held by the holding metal fitting. A surface-mounted piezoelectric vibrator, wherein the surface-mounted piezoelectric vibrator is adhesively fixed to the free end of the plate or the conductive plating part. 5. The adhesive used for the adhesive fixing is a first heat resistant and highly conductive adhesive applied to the bonding site, and a second heat resistant conductive adhesive covering the first heat resistant conductive adhesive. 5. The surface mount type adhesive according to claim 1, wherein the second heat resistant conductive adhesive has higher heat resistance than the first heat resistant conductive adhesive. Piezoelectric vibrator. 6. The surface mount piezoelectric vibrator according to claim 5, wherein the first and second heat resistant conductive adhesives are polyimide adhesives containing fillers of different components.