JPH0477576A - Piezoelectric buzzer and paint for forming its electrodes - Google Patents

Abstract

PURPOSE:To obtain the subject coating, containing metallic gold powder, a specific resol type phenolic resin, a saturated or an unsaturated fatty acid (metallic salt thereof) and graphite, and capable of improving capacity of electrodes in a state of excellently kept electric conductivity, screen printability, adhesion, solderability, etc. CONSTITUTION:The objective coating, containing a paste composed of (A) 85-96wt.% metallic gold powder and (B) 15-4wt.% resol type phenolic resin establishing the relations between respective transmittances of (l/n) = 0.8-1.2, (m/n) = 0.8-1.2, (b/a) = 0.8-1.2 and (c/a) = 1.2-1.5 when the infrared transmittances of a 2-monosubstitution product, a 2,4-disubstitution product, a 2,4,6-trisubstitution product, methylol group, dimethylene ether and phenyl group of the aforementioned resin measured by infrared spectroscopy are successively (l), (m), (n), (a), (b) and (c), and further having (C) a saturated or an unsaturated fatty acid (metallic salt thereof) in an amount of 0.1-8pts.wt., based on 100pts.wt. total amount of the components (A) and (B), and (D) graphite in an amount of required pts. wt. based on 100pts.wt. total amount of the components (A) and (B).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a piezoelectric buzzer and a conductive paint for forming its electrodes.

[Conventional technology]

As shown in FIG. 1, the piezoelectric buzzer has electrodes 2 formed on both sides of a piezoelectric vibrator 1, and lead wires 4 connected to the electrodes 2 either directly or via a metal elastic body 3.

Conventionally, silver paste has been used for the electrodes 2 in this piezoelectric buzzer, and as shown in FIG.
is formed, and thereafter, drying, baking, etc. are performed according to the flow shown in the figure, and a piezoelectric buzzer is manufactured.

[Problem to be solved by the invention]

The piezoelectric vibrator 1 of the piezoelectric buzzer is desired to be as thin as possible from the viewpoint of vibration characteristics. However, when thinning the piezoelectric vibrator, silver migration may occur in the electrode 2 when a DC voltage is applied in a humid atmosphere after the baking (approximately 800°C) in the conventional manufacturing method that involves drying, baking, etc. There is a problem in that it is not possible to reduce the thickness of 1.

A known method for thinning the film is heating and curing a conductive paste coating made of metal silver powder and a thermosetting resin, but in this case, the conductivity decreases and the coating on the insulating substrate is reduced. There was a problem that the adhesion of the coating film was poor.

Moreover, the capacity (Cap) of the piezoelectric vibrator by this method is
acity (resonance characteristics) is lower than that in the drying/baking method, and therefore there is also the problem that sufficient sound pressure cannot be obtained.

Therefore, the object of this invention is to solve the above-mentioned problems of the conventional silver paste, which are: 1) has good conductivity, 2) is suitable for screen printing and intaglio printing, and 2) is suitable for coating on insulating substrates. Good adhesion; ■ Capable of forming thin wire circuits; ■ Excellent solderability and soldering strength on paint films; ■ The conductivity of the conductive circuit of the solder coat can be maintained over a long period of time.
■Providing a gold paste that can improve electrode capacity.

[Means to solve the problem]

As a means for solving the above problems, this invention includes 85 to 96% by weight of metal gold powder A, 815 to 4% by weight of resol type phenolic resin, and a total of 100% of both A and B.
The resol type phenolic resin B consists of 0.1 to 8 parts by weight of saturated fatty acids or unsaturated fatty acids or metal salts thereof, and the required parts by weight of graphite, based on the weight part, and the resol type phenolic resin B has a 2-1 substitution product that it has. , 2.4-disubstituted product, 2.4.6-
The infrared transmittance of the trisubstituted product, methylol group, dimethylene ether, and phenyl group by infrared spectroscopy is j! , m, n,
Formation of a piezoelectric buzzer electrode made of a paste that satisfies the following relationship between each transmittance: (a) --0,8 to 1.2 (d) --1,2 to 1.5 when a, b, and c The paint was used for this purpose.

The weight part and particle size of the graphite mixed in the gold paste may be appropriately determined through experiments, etc., but for example, it is preferably 0.5 to 20 parts by weight based on the total of 100 parts by weight of A and B in the paste. The amount is 1 to 10 parts by weight, and the particle size is, for example, 0.1 to 10 fm, preferably 0.1 n to 1 μm.

Further, the total particle size of the gold paste may be 0.1 to 20 f1 m, preferably 1, n or less.

Then, electrodes made of the paste were formed on both sides of the piezoelectric vibrator, and lead wires were connected to the electrodes either directly or via an elastic body to construct a piezoelectric buzzer.

[Effect]

In the gold paste according to the present invention configured as described above, if the amount of metal gold powder blended is less than 85% by weight, the solderability will be poor, and if it exceeds 96% by weight, the metal gold powder will not be sufficiently bound. , the resulting electrode also becomes sagging, making it impossible to obtain the desired soldering strength, resulting in decreased conductivity and poor screen printability.

Preferably, the content in the blend with the resin is 88% by weight or more, more preferably 90 to 93% by weight.

Regarding the resol type phenolic resin used, its chemical amount, the amount of 2-1 substitution product is λ, the amount of 2.4-2 substitution product is μ, 2
．． 4.6-3 If the amount of substituent is ν, the amount of methylol group is α, the amount of dimethylene ether is β, and the amount of phenyl group is γ, then □n of the above structure
This means that ν ν is small. That is,
Compared to the amount of 2-1 substitution product λ and the amount of 2.4-2 substitution product μ,
2.4.6-3 The amount of substituent ν means that there is a large amount.

a a α α becomes. That is, it means that the amount α of methylol groups is larger than the amount β of dimethylene ether and the amount of phenyl groups γ.

In general, as the amount of 2.4.6-3 substitutions ν increases, the crosslinking density of the resol type phenolic resin increases.
n Electricity improves. However, on the contrary, the electrode tends to become hard and brittle, resulting in poor physical properties.

Also, if 2 is small, the solderability of the electrode will be poor. If - is large, the conductivity of the electrode will be poor.

α Therefore, for a resol type phenolic resin that makes the hardness of the obtained electrode appropriate and has both good conductivity and solderability, the n a shown in the above structure should be 1.2 to 1.5. is suitable.

If the blending amount of the resol type phenolic resin is less than 4% by weight, the metal gold powder will not be sufficiently bound, and the resulting electrode will also become weak, resulting in decreased conductivity and poor screen printability. On the other hand, if the overlap exceeds 15%, the solderability will not be favorable.

Saturated fatty acids, unsaturated fatty acids, or metal salts thereof include saturated fatty acids such as palmitic acid, stearic acid, and arachidic acid having 16 to 20 carbon atoms, and unsaturated fatty acids such as seamarin having 16 to 18 carbon atoms. acids, oleic acid, lyric acid, etc., and their metal salts include salts with metals such as potassium, copper, aluminum, sodium, and zinc.

The use of these dispersants is preferable in blending the metal gold powder with the resol type phenolic resin because it promotes fine dispersion of the metal gold powder into the resin and forms an electrode with good conductivity.

The blending amount of saturated fatty acids, unsaturated fatty acids, or metal salts thereof is in the range of 0.1 to 8 parts by weight, preferably 1 to 3 parts by weight, based on 100 parts by weight of the total amount of metal gold powder and resol type phenolic resin. Parts by weight.

If the amount of the dispersant is less than 0.1 part by weight, fine dispersion of the metal gold powder cannot be expected, and if it exceeds 8 parts by weight, the conductivity of the electrode will be reduced and the electrode and piezoelectric vibrator may be damaged. This is not preferable because it leads to a decrease in adhesion with the material.

In order to adjust the viscosity, the gold paste according to the present invention includes:
Common organic solvents can be used as appropriate. For example,
Butyl carpitol, butyl carpitol acetate,
These are known solvents such as butyl cellosolve, methyl isobutyl ketone, toluene, and xylene.

〔Example〕

With the compounding ratio shown in Table 1, the examples had gold powder diameter: 1μ, graphite particle size: 0.7μ, weight ratio to gold powder: 1%, 2.5%.
, 5% each were kneaded for 20 minutes using a tricycle roll to prepare a gold paste. In addition, the resol type phenolic resin has an infrared transmittance ratio of n n
The one with a-=1.31 was used.

As shown in Fig. 2, the gold paste prepared in Example 2 was applied to both sides of the pseudo substrate of the piezoelectric vibrator 1 to form electrodes 2, as shown in Fig. 2, and the capacitance thereof was measured. did. The results of Example 1 are shown in FIG.

This result shows that as the graphite content increases, the capacity increases.

In addition, conductivity, adhesion, solderability, soldering strength, and printability were tested and all were found to be satisfactory.

Figure 4 shows metal gold powder (diameter, 54) and graphite (diameter, 0.7
The degree of change in specific resistance due to gold paste electrodes with varying blending ratios of m) is shown. In this case, the ratio of metal gold powder to resin was 92:8 (wt%).

C Effects of the Invention] The present invention, configured as described above, can achieve a capacity close to that of conventional silver paste while maintaining good performance such as conductivity, screen printability, adhesion, and solderability. Obtainable. This does not cause a decrease in sound pressure and does not require baking, which improves manufacturing efficiency.Also, there is no risk that baking will cause migration later in a humid atmosphere, so it is possible to make the piezoelectric vibrator thinner. It is possible.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of an example of a piezoelectric buzzer according to the present invention, Fig. 2 is a manufacturing explanatory diagram of the same side, Fig. 3 is a graph showing the relationship between graphite addition amount and cavity, and Fig. 4 is a graphite content and ratio. FIG. 5 is a diagram illustrating the manufacturing of a conventional example. 1... Piezoelectric vibrator, 2... Electrode, 3
...Metal elastic body, 4...Lead wire. Patent Applicant Tuck Electric Cable Co., Ltd. Agent Aya Kamata Figure 2 Figure 3 Figure 4

Claims (3)

[Claims] (1) 85 to 96% by weight of metal gold powder A, 15 to 4% by weight of resol type phenolic resin B, and 0.00% of saturated fatty acid or unsaturated fatty acid or a metal salt thereof for a total of 100 parts by weight of both A and B. The resol type phenolic resin B consists of 1 to 8 parts by weight and the required part by weight of graphite.
It has 2-1 substitutions, 2, 4-2 substitutions, 2, 4
, 6-3 substituted product, methylol group, dimethylene ether,
The infrared transmittance of phenyl group by infrared spectroscopy is l, m,
When n, a, b, and c, between each transmittance (a) l/n = 0.8 to 1.2 (b) m/n = 0.8 to 1.2 (c) b/ A paint for forming a piezoelectric buzzer electrode comprising a paste that satisfies the following relationship: a=0.8-1.2 (d) c/a=1.2-1.5. (2) A paint for forming a piezoelectric buzzer electrode according to claim (1), wherein the metal gold powder A has a particle size of 0.1 to 20 μm. (3) Claims (1) to (2) are applied to both sides of the piezoelectric vibrator.
A piezoelectric buzzer consisting of an electrode made of any of the pastes and a lead wire connected to the electrode either directly or through an elastic body.