JPH0477570A - Coating for forming piezoelectric buzzer and its electrode - Google Patents

Abstract

PURPOSE:To obtain the subject coating, containing metallic nickel powder, a specific resol type phenolic resin, a saturated or an unsaturated fatty acid (metallic salt thereof) and a metallic chelating material, and excellent in adhesion of films onto insulating substrates, solderability, soldering strength, etc. CONSTITUTION:The objective coating which is a paste is obtained by blending (A) 100pts.wt. mixture composed of (i) 85-96wt.% metallic nickel powder and (ii) 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 measured by infrared spectroscopy are (l), (m), (n), (a), (b) and (c) with (B) 0.1-8pts.wt. (un)saturated fatty acid (metallic salt thereof) and (C) 1-50pts.wt. metallic chelating material.

Description

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

[Prior art]

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 film, conventional manufacturing methods such as drying and baking require the baking (approximately 8
00° C.), if a DC voltage is applied in a humid atmosphere, there is a risk that silver migration will occur in the electrode 2, and there is a problem that the piezoelectric vibrator 1 cannot be made into 1llllI.

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 were problems such as poor adhesion of the paint film.

Therefore, the object of this invention is to solve the above-mentioned problems of the conventional silver paste, which are as follows: 1) It has good conductivity, 2) It is suitable for screen printing and intaglio printing, and 2) It is suitable for coating on insulating substrates. We propose a nickel paste that has good adhesion, ■ allows the formation of thin wire circuits, ■ has excellent solderability and soldering strength on coatings, and ■ maintains the conductivity of conductive circuits in solder coats over a long period of time. It is in.

(Means for solving one problem) In order to solve the above problem, in the present invention, 85 to 96% by weight of metal nickel powder A, 815 to 4% by weight of resol type phenolic resin, and both A , B total 10
0 parts by weight, 0.1 to 8 parts by weight of saturated fatty acids or unsaturated fatty acids or metal salts thereof, and 1 to 50 parts by weight of a metal chelate forming agent, and the resol type phenolic resin B is 2-1 substitution product having 2.4-2
When the infrared transmittance of the substituted product, 2.4.63 substituted product, methylol group, dimethylene ether, and phenyl group by infrared spectroscopy is expressed as l, m, n, a, b, and c, each transmittance is Between (a) - = 0.8 to 1.2 (b) - = 0.8 to 1.2 (c) - 0,8 to 1.2 (d) - 1,2 to 1.5 We adopted a piezoelectric buzzer electrode-forming paint consisting of a paste that satisfies the following relationship.

The above metal nickel powder A has an average particle diameter of 0°1 to 207
111, preferably 1n or less.

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]

The nickel paste according to the present invention configured as described above has poor solderability when the amount of metallic nickel powder is less than 85% by weight, and conversely, when it exceeds 96% by weight, the metallic nickel powder is sufficiently bound. Otherwise, the resulting electrode will be weak, the desired soldering strength will not be obtained, the conductivity will be reduced, and the screen printability will also be poor. 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 phenol resin used, its chemical weight, the amount of 2-1 substitution product is λ, the amount of 2.4-2 substitution product is p, 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 T, then the fact that L of the above structure is large means that J −
is n
This means that ν ν is small. That is, it means that the amount of 2.4.6-3 substitution product V is larger than the amount λ of 2-1 substitution product and the amount of 2.4-2 substitution product μ.

Also, if ``2 -'' in the above configuration is large, a
a This means that 17 is small and α
α, which means that the amount α of methylol groups is larger than the amount β of dimethylene ether and the amount T of phenyl groups.

Generally, as the amount ν of 2.4.6-3 substituents increases, the crosslinking density of the resol type phenolic resin increases, so the above-mentioned 21. The smaller is ν, that is, ``L, and the larger is the electrode conductivity n.
n Electricity improves. However, on the contrary, the electrode tends to become hard and brittle, resulting in poor physical properties.

Also, if the width is small, the solderability of the electrode will be poor. If the top 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, z b shown in the above structure is 0.8 to 1.2, respectively.
It is suitable that n na 'yo is 1.2 to 1.5.

If the blending amount of the resol type phenolic resin is less than 4% by weight, the metal nickel powder will not be sufficiently bound, and the resulting electrode will also 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, such as oleic acid and lyric acid, 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 metallic nickel powder with the resol type phenolic resin because it promotes fine dispersion of the metallic nickel 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 8 parts by weight, based on 100 parts by weight of the total amount of metal nickel powder and resol type phenolic resin. It is 3 parts by weight.

If the amount of the dispersant is less than 0.1 part by weight, fine dispersion of the metal nickel 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.

As the metal chelate forming agent, at least one selected from aliphatic amines such as monoethanolamine, jetanolamine, triethanolamine, ethylenediamine, triethylenediamine, and triethylenetetraamine is used.

The metal chelate forming agent added prevents oxidation of the metal nickel powder, contributes to maintaining conductivity, and further improves solderability.

The amount of the metal chelate forming agent used is in the range of 1 to 50 parts by weight based on 1.00 parts by weight of the total amount of the metal nickel powder and the resol type phenolic resin.

If the amount of the metal chelate forming agent is less than 1 weight, the conductivity will decrease and the solderability will not be favorable.

On the other hand, when it exceeds 50 parts by weight, the viscosity of the paste itself decreases too much, which impairs printability, which is not preferable.

In the nickel paste according to the present invention, an ordinary 411 solvent can be appropriately used to adjust the viscosity. For example, known solvents include butyl carpitol, butyl carpitol acetate, butyl cellosolve, methyl isobutyl ketone, toluene, xylene, and the like.

〔Example〕

Particle size 1. n metallic nickel powder, a resol type phenolic resin with an infrared transmittance ratio shown in Table 1, an oleic resin potassium, and triethanolamine in the proportions shown in Table 2 (parts by weight), and some butyl calpitol as a solvent. In addition, a nickel paste was prepared by kneading with a tricycle roll for 20 minutes.

In particular, in Example 3, the average particle size of the metallic nickel powder was: 1-
1 and 2 had the same average particle size: 0.5 Jlll.

As shown in the flowchart of FIG. 2, each of these examples is coated on both sides of the pseudo substrate of the piezoelectric vibrator 1 by screen printing to form the electrodes 2. In order to examine the various characteristics of the electrodes 2, first, Each piezoelectric vibrator 1 with electrodes 2 is immersed in an organic acid flux bath for 4 seconds, and then immersed in a 250°C molten solder bath (P
b/5n-40/60) for 5 seconds, and at the same time, was blown with hot air at 2 to 6.0 atm and 220 to 230°C, and then washed.

At this time, the average thickness of the solder coat soldered to the electrode 2 is 1
It was 0n.

Table 2 shows the results of examining various characteristics of electrode 2 that were obtained during this process.

Here, the electrical conductivity of the electrode is a value obtained by measuring the volume resistivity of the electrode 2 that has been heat-cured.

The adhesion of an electrode is determined by drawing 11 vertical and horizontal parallel lines at 1 m+ intervals on the coating film that will become the electrode, in accordance with the base grain test method of JIS K5400 (1979).
Make cuts in the shape of substrate so that 100 squares are formed in cii, and when the coating film is peeled off with cellophane tape, calculate the number of substrate squares of the coating film remaining on the insulating substrate. It is something that

Solderability was evaluated by observing the soldered state on the electrode 2 using a low magnification stereoscopic microscope and using the following criteria.

○ mark: The surface is smooth and the solder is adhered to the entire surface. △ mark: The electrode is partially exposed. × mark: The solder is only partially attached. Printability refers to the viscosity adjustment. When forming the electrode 2 by a screen printing method using the NINKEL paste obtained in the above, the ease of printing was observed and evaluated according to the following criteria.

O mark: Good formation of electrode 2 △ mark: Slightly difficult formation of electrode 2 × mark: Case where formation of electrode 2 is difficult (For example, G10) with a land with a diameter of 3 strokes and a thickness of 25 mm.
Form a coating film of ~30tna and heat at 130~180°C
After curing the coating film by heating for 10 to 60 minutes, a lead wire (tin-plated annealed copper wire of 0.8++ mφ) is vertically soldered (using 63Sn eutectic solder) onto the land, and The lead wire was pulled vertically at a tensile speed of 50 wa/min with the lead wire fixed, and its strength was determined.

As can be seen from the results, each example has an appropriate combination of specific compounded materials, resulting in improved conductivity of the electrode (coating film), adhesion of the electrode, solderability, soldering strength, and printability. It has good properties such as: Further, the obtained cured electrode can be directly soldered using a normal organic acid fluxing agent.

Next, regarding Comparative Examples, in Comparative Examples 1, 2, and 3, the infrared transmittance ratio of the resol-type phenolic resin used was not appropriate, and therefore the electrode 2 with preferable solderability could not be obtained. Comparative Example 4 is not preferable because the amount of metal 2.2 Kel powder is small, so that the solder only partially adheres to the piezoelectric vibrator 1 during soldering. In Comparative Example 5, there was a large amount of metallic nickel powder, and the metallic nickel powder was not sufficiently bound, so the conductivity of the electrode was unstable, and the resulting electrode 2 was also unstable.
In addition, screen printability is somewhat difficult, which is not preferable.

〔Effect of the invention〕

As explained in detail above, the piezoelectric buzzer in which electrodes are formed using the electrode forming paint according to the present invention improves manufacturability because baking is not required when forming the electrodes, and the baking can be done later. Since there is no fear of migration in a humid atmosphere, the piezoelectric vibrator can be made thinner.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of a piezoelectric buzzer according to the present invention, FIG. 2 is an explanatory diagram of manufacturing the same embodiment, and FIG. 3 is an explanatory diagram of conventional manufacturing. 1... Piezoelectric vibrator, 2... Electrode, 3
...Metal elastic body, 4...Lead wire. Margin Table Below Margin Figure 1 Figure 2 Figure 3

Claims (3)

[Claims] (1) Metallic nickel powder A85-96% by weight, resol type phenolic resin B15-4% by weight, and both A and B
The resol type phenolic resin B consists of 0.1 to 8 parts by weight of a saturated fatty acid or an unsaturated fatty acid or a metal salt thereof, and 1 to 50 parts by weight of a metal chelate forming agent based on a total of 100 parts by weight of 2-1 substitution product it has,
Let the infrared transmittance of the 2,4-2 substituted product, 2,4,6-3 substituted product, methylol group, dimethylene ether, and phenyl group by infrared spectroscopy be l, m, n, a, b, and c. When,
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 (ni) ) A paint for forming piezoelectric buzzer electrodes comprising a paste satisfying the following relationship: c/a=1.2 to 1.5. (2) The metal nickel powder A has an average particle diameter of 0.1 to
The coating material for forming a piezoelectric buzzer electrode according to claim 1, wherein the coating material has a thickness of 20 μm. (3) The above-mentioned claim (1) or (
A piezoelectric buzzer comprising an electrode made of the paste described in 2) and a lead wire connected to the electrode directly or through an elastic body.