JPH01272783A - Enameled base plate and production thereof - Google Patents

Abstract

PURPOSE:To produce an enameled base plate having an enamel layer controlled in heat conductivity by coating a metallic base plate with both an inner layer high in porosity having large blister diameter and an outer layer low in porosity having small blister diameter. CONSTITUTION:A first layer (inner layer) having about 50-200mum thickness is electrodeposited with electrophoresis by immersing a metallic base plate in slurry wherein the crystallized enamel frits having 10-20mum average particle diameter and comparatively large particle diameter are dispersed. Then while this electrodeposited layer is not dried, the base plate is immersed in slurry having particle diameter smaller than the above-mentioned slurry wherein the crystallized enamel frits having 0.5-5mum average particle diameter and small particle diameter are dispersed and a second (outer layer) having about 5-50mum thickness is electrodeposited thereon. Furthermore after drying the base plate electrodeposited with the first and second layers, it is calcined at about 800-950 deg.C to form the enamel layer made of two-layer ceramic on the metallic base plate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an enamel substrate with improved characteristics.

More specifically, regarding an enamel substrate having an enamel layer with adjusted thermal conductivity, it is particularly useful for controlling heat diffusion when applied to a substrate for a thermal printer head.
This invention relates to an enamel substrate with improved printing efficiency.

[Conventional technology]

The characteristics required of a substrate for a thermal printer head are that when current is passed through the heating circuit, the temperature rises to a high temperature of 300 to 400°C in an extremely short time of several 7 FL sec or less, and when the current is turned off, the temperature remains the same. There is a need for properties that allow the temperature to drop to room temperature in a short period of time at a certain speed.

In contrast, alumina substrates are currently mainly used, but the thermal conductivity of alumina substrates is too high for the above-mentioned required characteristics, making it difficult to raise the temperature in a short period of time. Therefore,
In order to eliminate this drawback, an RFJ glass layer with low thermal conductivity is provided on the surface of the alumina substrate, and then a circuit is formed and used.

However, in an alumina substrate provided with a glass layer in this way, if it is repeatedly turned on and off by energization,
It has the disadvantage that heat gradually accumulates in the alumina base material, resulting in poor cooling performance. For this reason, currently, a heat sink is attached to this alumina substrate.

To solve this problem, there is a tendency to use an enamel substrate in which an enamel layer is provided on a metal core.

Since the metal core has high thermal conductivity, it can solve the problem of temperature drop.

A known example of using an enamel substrate for a thermal printer head is JP-A-62-109,984.

This is an insulating enamel substrate formed by electrodepositing glass powder onto a gold R substrate using a suspension of crystallized glass and firing it.

[Problem to be solved by the invention]

In the case of an enameled substrate, as mentioned above, the glass on the surface acts as a heat storage layer, and when the current is turned off, heat escapes to the metal core, making it suitable for use as a substrate for thermal printer heads. Therefore, the above-mentioned known enamel substrate can be used as is for a normal thermal printer head.

When using an enameled substrate as a substrate for a thermal printer head, various characteristics are required.

■Acid resistance, heat resistance... Good if crystallized glass enamel is used. 0 Surface smoothness: Good surface smoothness can be obtained by using fine glass. ■Heat dissipation property: The board as a whole needs to have good heat dissipation property, and the enamel board has good heat dissipation properties as a whole because the enamel is applied on the metal core. ■Surface heat storage layer: A heat storage layer with low thermal conductivity is required on the substrate surface. This is to instantaneously and sufficiently raise the temperature when a current is passed through the heating element formed on the surface of the substrate. However, this layer must not be very thick and must have an appropriate thermal conductivity so that the temperature drops immediately when the current is turned off.

For normal thermal printer heads, the known enamel substrate can be used as is, but in order to further increase efficiency, that is, print faster with less power, it is necessary to lower the thermal conductivity of the glass. .

However, in order to lower thermal conductivity, changing to glass made of a material with low thermal conductivity has the disadvantage that acid resistance and heat resistance will be insufficient.

An object of the present invention is to provide an enamel substrate suitable for use in a highly efficient thermal printer head, which has a low thermal conductivity of the enamel layer while maintaining surface smoothness, acid resistance, and heat resistance.

[Means to solve the problem]

The present inventors conducted extensive research to solve the above problems. As a result, the problem can be solved by having two enamel layers, using glass with good acid resistance, heat resistance, and smoothness for the upper layer, and glass with low heat conductivity S coefficient for the lower layer. The present invention has been completed by discovering that the problem can be solved by retaining a large number of bubbles with a large diameter in the glass.

That is, the present invention is an enamel substrate formed by covering a metal substrate with an inner layer having a large bubble diameter and a high porosity, and an outer layer having a small bubble diameter and a low porosity than the inner layer.

In addition, the manufacturing method includes immersing a metal substrate in a slurry in which crystallized enamel frit with a relatively large average particle size of 10 to 20 μm is dispersed, and then electrodepositing the first layer by electrophoresis. Immediately without drying the electrodeposited layer, the particle size is smaller than that of the slurry, and the average particle size is 0.5.
The substrate is immersed in a slurry containing small crystallized enamel frits of ~5 μm, and a second layer is electrodeposited with N.
The method for manufacturing the above-mentioned bowlou substrate is characterized by comprising a step and a step of firing the 11il and the second FM after electrodeposition.

In order to form an enamel layer with small bubble diameter and low porosity as an outer layer, fine crystallized glass having an average particle size of 0.5 to 5 μm may be used.

On the other hand, to lower the thermal conductivity of the inner enamel layer, you can of course use glass that has a low thermal conductivity, but such glass generally has poor acid resistance and heat resistance in many cases. Therefore, in the present invention, a glass is used that forms a glass layer containing many large bubbles (voids) after firing. In order to form a glass layer containing many bubbles, it is necessary to use a large crystallized glass with an average particle size of 10 to 20 μm during electrodeposition, and the maximum bubble size is about 50 μm.
The porosity can be 10% or more.

This allows the thermal conductivity to be lowered.

Here, the particle size is 10 to 20 μm because the particle size is 10 μm.
This is because if it is less than 20 μm, the bubble diameter and porosity become small, so that the thermal conductivity does not decrease, and if it exceeds 20 μm, it will adversely affect the condition of the enamel surface. Of course, foamable glass may be used to contain more air bubbles.

The inner Fy4 (lower layer) has a film thickness of 50 to 200 after firing.
It is preferable that the outer layer (upper layer) has a thickness of about 5 to 50 μm.

In performing this two-layer coating, ffi deposition by electrophoresis is effective. In other words, the electrodeposition method has good throwing power, so it can be deposited to a uniform thickness over the entire surface, and not only does it avoid thick deposits on the edges, but also allows the upper and lower layers to be made to any desired thickness. This is because the thermal conductivity can be easily adjusted. During electrodeposition, the lower layer is first electrodeposited, and without drying, it is immediately placed in a separate electrodeposition bath and the upper layer is electrodeposited. This is because if the glass layer is dried for a second time, the glass layer will crack and peel off when it is placed in the bath again. Furthermore, if the lower layer is once dried and fired, an insulating layer is formed on the surface of the substrate, making it impossible to apply nitrogen again to the upper layer.

To explain the electrodeposition of glass fine particles in more detail, the glass material is first melted at a high temperature and then cooled in a cooler to obtain a glass ceramic cullet. This is pulverized using a pulverizer such as a ball mill. After that, some large particles were removed, and glass ceramic powder and isopropyl alcohol were added to a ball mill, and the average particle size in the multilayer cumulative particle size distribution of glass ceramics (50 wt.
% value) is 10 to 20 μm to create a suspension (slip), and put it in an electrophoresis tank.
Glass ceramics are electrophoretically electrodeposited at a voltage of 50-600V. After this, without drying, immediately fill a separate electrophoresis tank with the milled slip to an average particle size of 0.5 to 5 μm, transfer it to this tank, perform electrodeposition, and adjust the film thickness after firing. In terms of lower layer 50 to 200 μm,
Electrodeposition is performed for a time such that the upper layer has a thickness of 5 to 50 μm.

After the substrate is pulled up and dried, it is fired at 800 to 950°C to obtain two smooth enamel layers of glass ceramics on the core metal.

A heating resistor, lead electrodes, and a wear-resistant layer are formed as thin films on this insulating substrate to produce a thermal head.

〔Example〕

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited thereto in any way.

After cleaning the stainless steel plate with a smooth surface, two-layer coating is applied.
After firing, the glass was peeled off and the thermal conductivity was measured by a laser flash method.

Usually, a steel plate for enameling is used as the metal core, and after surface treatment such as degreasing, pickling, and Ni plating, coating is performed.
Firing is performed, and the reason why a smooth stainless steel plate is used here is to make it easier to peel off the glass.

After cleaning a smooth stainless steel plate, a crystallized glass with a large particle size (average particle size 15 μm) (Bad shown in Japanese Patent Publication No. 61-2970) is prepared.

S t 02. B2O3, VOO glass) was coated by electrodeposition. Subsequently, crystallized glass having the same composition and smaller particle size (average particle size 3 μTrL) was electrodeposited, dried, and fired (850° C., 10 minutes).

The film thickness was such that the first layer (lower layer) was 200 μm and the second layer (upper layer) was 50 μm after firing.

When this glass was peeled off from a stainless steel plate and its thermal conductivity was measured using the laser flash method, it was found to be 0.002.
4 cal/c-sec-"C.

In the case of glass of the same composition, with only one layer of glass with an average particle size of 9 μm electrodeposited and fired, the thermal conductivity is 0.0029c.
al /z-sec ・'C In this example, the thermal conductivity could be lowered by about 17% compared to Lunotekore.

(Comparative example) In the example, the average grain size of the first layer of crystallized glass was 8 μm.
The procedure was the same as in the example except that the glass layer was peeled off from the stainless steel plate and the thermal conductivity was measured by the laser flash method.When the average particle size was 8 μm, the thermal conductivity was 0.0030 Cal/cII. -sec
, °C, and no effect of having two layers was observed. Furthermore, when the average particle size is 21 μm, the thermal conductivity is 0.00.
The temperature was 23 cal/cm·sec·°C, which achieved the objective, but the surface smoothness deteriorated.

In addition, the procedure was carried out as in the example except that the average particle size of the 21st crystallized glass was 0.3 μm and 7 μm, and the glass layer was peeled off from the stainless steel plate and the thermal conductivity was measured by the laser flash method. Both 0.0024ca
1/3-se (e"c, which was satisfactory in terms of thermal conductivity. However, with an average particle size of 0.3 μm, the average bubble diameter becomes smaller, but the softening and flow time during firing becomes shorter, and desorption becomes more difficult. A smooth surface could not be obtained, probably because it was difficult to form bubbles.

Further, when the average particle size was set to 7 μm, the average bubble size generated was large and a smooth surface could not be obtained.

(Effects of the Invention) It was possible to reduce the thermal conductivity of the entire glass layer while maintaining the surface properties of the enamel substrate, such as acid resistance, heat resistance, and smoothness.

Moreover, the value could be changed freely within a certain range.

Therefore, when this substrate is used in a thermal printer head,
This means you can print faster and with less power.
Combined with rapid heat dissipation due to the enamel substrate, extremely Br
Enables Ie rate printing.

This invention has great practical effects.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating a 133x microscopic photograph of a cross section of the enamel substrate of the present invention. Applicant's agent Hiroshi Fujimoto Public name 1

Claims (1)

[Scope of Claims] 1. An enamel substrate formed by covering a metal substrate with an inner layer having large bubble diameters and high porosity, and an outer layer having smaller bubble diameters and lower porosity than the inner layer. 2. A metal substrate is immersed in a slurry in which crystallized enamel frit with a relatively large average particle size of 10 to 20 μm is dispersed, and the first layer is electrodeposited by electrophoresis. Immediately, without drying, the substrate is immersed in a slurry in which small crystallized enamel frits having a particle size smaller than that of the slurry and an average particle size of 0.5 to 5 μm are dispersed, and an electrodeposition process is carried out to electrodeposit a second layer. 2. The method of manufacturing an enameled substrate according to claim 1, further comprising a step of depositing the first layer and the second layer and then firing the first layer and the second layer after electrodeposition.