JPH0477573A - Piezoelectric buzzer and paint for forming its electrodes - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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. 8, the silver paste is applied to both sides of the piezoelectric vibrator 1 by printing.
is formed, and thereafter, drying, baking, etc. are performed according to the flow shown in the figure, and a piezoelectric buzzer is manufactured.

[Problem I that the invention attempts to solve]

The piezoelectric vibrator 7 of the piezoelectric buzzer is desired to be as thin as possible from the viewpoint of vibration characteristics. However, when thinning the film, conventional manufacturing methods such as drying and baking require the baking (approximately 8
When DC voltage is applied in a humid atmosphere after 00°C), electrode 2
There is a problem that silver migration may occur in the piezoelectric vibrator 1, making it impossible to reduce the thickness of the piezoelectric vibrator 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. ■ Has good conductivity. ■ Can be easily screen printed or intaglio printed. ■ Adhesiveness of the coating film to the insulating substrate. ■Can form thin wire circuits; ■Solderability and soldering strength on the coating film are low; ■The conductivity of the conductive circuit of the solder coat can be maintained for a long time.
■Providing a palladium paste that can improve electrode capacity.

[Means to solve the problem]

As a means for solving the above problems, in this invention, metal palladium powder A85 to 96% by weight, resol type phenolic resin BI5 to 4fif%, and saturated fatty acid or The resol type phenolic resin B is composed of 0.1 to 8 parts by weight of unsaturated fatty acids or metal salts thereof and the required parts by weight of carbon blank, and the resol type phenolic resin B has a 2-1 substitution product, 2.4-2
When the infrared transmittance of t-substituted, 2.4.6-3-substituted, methylol group, dimethylene ether, and phenyl group by infrared spectroscopy is l, m, , n, a, b, and c, each transmission Between the ratios (a) - = 0.8 to 1.2 (o) - = 0.8 to 1.2 (c) - = 0.8 to 1.2 (d) - = 1.2 to 1 We adopted a piezoelectric buzzer electrode forming paint consisting of a paste that satisfies the following relationship:

The weight part and particle size of the carbon blank mixed in the palladium paste may be appropriately determined through experiments, etc., but for example, 0.5
~20 parts by weight, preferably 1~0 parts by weight, and the particle size is, for example, 15 (10-3t) nm-lnm, preferably 100 wl-50 nm.

In addition, the palladium powder particles of the above palladium paste were added to 0.
The electrode can be formed with a thickness of 1 to 20μ, preferably 1μ or less. A carbon blank may be further added as palladium powder particle size within this range.

Then, electrodes made of the paste having the above-described structure were formed on both sides of the piezoelectric vibrator, and lead wires were connected to the electrodes either directly or through an elastic body, thereby constructing a piezoelectric buzzer.

[Effect]

In the palladium paste according to the present invention configured as described above, if the amount of metal palladium powder is less than 85% by weight, the solderability will be poor, whereas if it exceeds 96% by weight, the metal palladium powder will not bind sufficiently. Otherwise, the resulting electrode becomes brittle, the desired soldering strength cannot be obtained, the S conductivity decreases, and the screen printability also deteriorates. 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 weight, the amount of 2-1 substitution product is λ, the amount of 2.4-2 substitution product is μ, and the amount of 2-1 substitution product is μ, 2.
．． 4.6-3 The amount of substituents is ν, the methylol group is α, the amount of dimethylene ether is β, and F! If the amount of phenyl group is γ, this means that the above structure is small. That is, the amount of 2-1 substitution product λ
, 2.4-2 substituent amount μ, means that 2.4.6-3 substituent amount ν is larger.

Electricity improves. However, on the contrary, the electrodes are hard and tend to bend, resulting in poor physical properties.

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

α Therefore, as a resol type phenolic resin that makes the hardness of the obtained electrode appropriate and has both good conductivity and solderability, α α shown in the above structure is used. That is, it means that the methylol group α is larger than the dimethylene ether amount β and the phenyl group amount γ.

In general, as the amount ν of 2.4.6-3 substituents increases, the crosslinking density of the resol type phenolic resin becomes thicker and □ is 1.2 to 1.
．． A value of 5 is appropriate.

If the resol type phenolic resin is less than 4% by weight, the metal palladium powder will not be sufficiently bound, and the resulting electrode will become brittle, resulting in decreased conductivity and poor screen printability. On the other hand, if it exceeds 15% by weight, 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 palladium powder with the resol-type phenolic resin because it promotes fine dispersion of the metal palladium 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 01 to 8 parts by weight, preferably 1 to 3 parts by weight, based on 100 parts by weight of the total amount of metal palladium powder and resol type phenolic resin. Department.

If the amount of the dispersant is less than 0.1 part by weight, fine dispersibility of the metal palladium 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 vibration This is undesirable because it leads to a decrease in adhesion with the child.

In the palladium paste according to the present invention, an ordinary organic solvent can be appropriately used to adjust the viscosity.

For example, butyl carpitol, phthyl carbitol acetate, butyl cellosolf, methyl isobutyl ketone,
Known solvents such as toluene and xylene.

[Example] With the compounding ratio shown in Table 1, Example 1 had palladium powder particle size: 0.8 m, 1. Oμ, 1.3 um, 3.0um, 5
．． Palladium pastes were prepared by kneading seven types of pastes, 0 um, 15 instant, and 20 μs, for 20 minutes each in a three-screw ball. In Example 2, palladium powder diameter: 5.0 trm, carbon black particle diameter: 40 nm, 25 nm, 16 nm,
Weight ratio to palladium powder: 1%, 2.5%, 4%,
A palladium paste was prepared by selecting an appropriate amount from among 5%, 6%, 7.5%, and 9% and kneading each with a triaxial roll for 20 minutes. The resol type phenol resin used had an infrared transmittance ratio of C--1.31.

As shown in FIG. 2, the palladium paste of Example 1.2 prepared as shown in the table was applied to both sides of the substrate of the piezoelectric vibrator 1 to form electrodes 2, as shown in FIG. Capacity was measured. The results of Example 1 are shown in FIG. 3, and the results of Example 2 are shown in FIG. 4.

From this result, it can be seen that as the metal palladium powder diameter becomes smaller, the capacity increases, and as the carbon blank content (added amount) increases, the capacity C/ity also increases.

In addition, when testing conductivity, adhesion, solderability, soldering strength, and printability, it was found that sufficient conductivity could not be obtained with a palladium powder diameter of 0.5 m or less. Although the solderability deteriorated in the following cases, the results were satisfactory in other respects.

As described above, the smaller the particle size of metal palladium powder, the better the capacitance, but problems arise with IT properties and solderability. This is considered to be because the smaller the particle size, the easier it is to enter the surface of the pseudo 4Q substrate (plate voltage vibrator 1), and the degree of bonding is improved. For this reason, it can be seen that it is preferable to apply a plurality of pastes to form the electrode 2 in multiple layers, with small-diameter grains on the piezoelectric vibrator 1 side and large-diameter grains on the lead wire 4 side.

In addition, in the case of metal palladium powder diameter: 5.0 μm and carbon black diameter: 37 nw, metal palladium (
Blending ratio of Ag) and resol type phenolic resin (Re) (
Weight ratio) 86: 14.88: 12.90:
10.92:08.93:07.94:06
The electrode 2 was formed using the palladium paste as described above, and the filling amount of the carbon plaque was varied, and the relationship between the filling amount and the capacity is shown in FIG.

Figure 6 shows the capacitance of palladium paste electrodes with varying amounts of metal palladium powder (particle size: 5μ) (weight ratio to resin; for example, 88 in the figure means palladium powder: resin = 88:12). The relationship with filling amount is shown.

FIG. 7 shows the degree of change in resistivity caused by palladium paste electrodes in which the mixing ratio of metal palladium powder (diameter: 5 μm) and carbon blank (diameter: 40 nm, 25 nm to 116 nm gloss) was varied. In this case, metal palladium powder:
The resin was 92:8 (wt%).

〔Effect of the invention〕

Since the present invention is constructed as described above, it is possible to obtain a cavity electrode close to conventional silver paste while maintaining various properties such as conductivity, screen printability, adhesion, and solderability. Therefore, there is no reduction in sound pressure, and there is no need for baking, which improves manufacturing efficiency.The baking also eliminates the risk of migration in a humid atmosphere, making it possible to make the piezoelectric vibrator thinner. .

[Brief explanation of drawings]

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 diagram showing the relationship between metal palladium powder diameter and capacity, and Fig. 4 is a diagram showing the addition of carbon black. Figure 5 is a diagram showing the relationship between carbon blank addition amount and capacity. Figure 6 is a diagram showing the relationship between metal palladium powder filling amount and capacity. Figure 7 is carbon black content and specific resistance. FIG. 8 is a manufacturing explanatory diagram of a conventional example. 1... Piezoelectric vibrator, 2... Electrode, 3
...Metal elastic body, 4...Lead wire. Patent Applicant Tuck Electric Wire Co., Ltd. Agent Aya Kamata Figure 2 Palladium powder filling amount (weight i1%) Figure 5 P d /Re 6810 wealth 2 4 Carbon black addition m (main gate %) Figure 7 -e- 1finm Figure 3 Figure 4 Figure 8

Claims (3)

[Claims] (1) 85 to 96% by weight of metal palladium powder A, 15 to 4% by weight of resol type phenolic resin B, and both A,
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 carbon black, based on a total of 100 parts by weight of B. 2-1 substitution product, 2,
4-2 substituted product, 2, 4, 6-3 substituted product, methylol group,
When the infrared transmittances of dimethylene ether and phenyl groups measured by infrared spectroscopy are defined as l, m, n, a, b, and c, there is a difference between each transmittance (a) l/n=0.8 to 1. 2 (b) m/n = 0.8 to 1.2 (c) b/a = 0.8 to 1.2 (d) c/a = 1.2 to 1.5 Consists of a paste that satisfies the following relationship. Paint for forming piezoelectric buzzer electrodes. (2) A paint for forming a piezoelectric buzzer electrode according to claim (1), wherein the metal palladium 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.