JPS5821833B2 - Craze substrate for thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a glazed substrate in which a glazed layer is formed on an insulating substrate.

Insulating substrates such as ceramic plates and glass plates that have electrical insulation properties are used to maintain insulation properties and adjust heat dissipation.
It is often used as an insulating substrate whose surface is coated with glass and has a glaze layer formed thereon.

For example, a thermal head is formed by disposing a resistive heating element on such an insulating substrate, and is used as a thermal element for a thermal type of facsimile printing.

The importance of recording information such as data and graphics has been increasing in recent years, but there is a strong demand for efficient recording methods, and there are various recording methods, but thermal recording methods are particularly popular. This method has attracted a lot of attention, and in the case of this method, recording is performed using a thermal head mainly composed of a heating resistor provided on the above-mentioned glazed insulating substrate.

That is, for example, a thermal head is used that is made of an insulating substrate such as an alumina substrate with a glaze layer formed on the surface, and these are used as many small heating elements, and pulsed power is applied to them to generate heat. Thermal energy is supplied to the thermal recording paper that passes over these heating elements to cause color development and predetermined recording.

The characteristics required for such a thermal head are long life, reliability, high-speed printing with excellent print quality, and
In addition, the power consumption must be as low as possible.

However, when performing thermal recording using a thermal head with such characteristics, the heating element disposed on the glaze layer generates heat and cools over and over again in order to receive repeated application of power. As a result, the glaze layer directly under the heating element will also be subjected to thermal shock.

As a result, the brace layer may bulge or breakage occurs, resulting in damage to the heating element, shortening its lifespan, and making long-term thermal recording impossible.

Conventionally, when glazing the surface of an insulating substrate, etc., only the ease of glazing was considered, and the composition of the glaze layer was determined based on how well it would adhere to the substrate and how it could be formed while increasing the aesthetic effect. The composition of the glass to be used was determined.

Therefore, when subjected to the above-mentioned thermal shock, various problems such as blistering occur, and this has many drawbacks, especially as an insulating substrate used in a thermal head.

The present invention has been made to eliminate such defects, and the glaze layer becomes defective when subjected to thermal shock due to repeated heat generation from a resistance heating element formed on the glazed surface. The present invention provides an improved glaze substrate that is free from glaze.

In other words, the transition point, softening point, thermal expansion coefficient, thermal conductivity, composition, etc. of the glass that makes up the glaze layer formed on the substrate are specified, and the glaze layer is formed to have good characteristics against thermal shock. The method is characterized by obtaining a glazed substrate.

Embodiments of the present invention will be described below using an insulating substrate used in a thermal head as an example.

As shown in FIGS. 1 and 2, a glaze layer 2 is formed by coating and baking glass on an alumina substrate 1. On top of this, a metal paste is coated in a predetermined pattern and baked to form a resistive heating element 3 and electrodes. Lead 4 is formed.

A wear-resistant layer 5 is formed to cover the entire heating element to obtain a thermal head.

Since a thermal head generates heat by passing a current through the heating element, power consumption is essentially high.

However, the more energy that is injected into the element that is used to raise the temperature of the element, the more efficient thermal printing can be achieved, so the printer is configured that way, and heating and cooling with a large temperature difference are repeated. The glaze layer will undergo a thermal shock.

When subjected to such a thermal shock, the transition point or softening point of the glass constituting the glaze layer becomes a problem.

That is, if the transition temperature of the glass is higher than the maximum temperature of the heating element when it generates heat, the occurrence of defects can be prevented.

This temperature is 550°C or higher.

Cracks or deformation occur when the temperature is less than 550°C.

The transition point of the glass is preferably 600°C, most preferably 650°C.

Further, in order to prevent any defects from occurring in the glaze layer and not to affect the resistance heating element, the glass constituting the glaze layer may have a softening point of 700° C. or higher.

Preferably it is 800°C, most preferably 820°C.

Furthermore, the thermal expansion coefficient and thermal conductivity of the glass constituting the glaze layer are 45 to 70X10-7/C and 1, respectively.
, 8~2.8X10'' cal 7cm, s 0°C.

If the coefficient of thermal expansion is outside the above range, cracks will appear in the glass.

In addition, when the thermal conductivity is outside the above range, 1.8×10-3
If it is smaller than cal/crrL, s, °C, when a constant pulse current is applied to the heating element, the temperature of the heating resistor element will rise rapidly due to the small thermal conductivity, but even if the pulse current is cut off, the temperature will rise rapidly. It is difficult to cool down until the application of 2.8 × 10-” cal 7c
When m, s, and 'C are larger, contrary to the case where they are smaller, the temperature rises slowly, the maximum temperature becomes low, the print density becomes low, and more power is required.

Further, representative examples of the compositions of these glasses are listed in the following table (described later).

On the other hand, a ceramic plate is suitable as a substrate on which a glaze layer is formed on which a heating element is arranged, and among ceramic plates, those made of alumina exhibit particularly excellent effects. Preferably 90-99
．． A material made of 5% alumina is preferable.

Glass sample number for table craze 12345 Composition (a) S 102 50.0 6.5 54.3 46.
0 30.0Ba0 24.4 10 -
20.0 - Sample number 12345 Composition (a) Ca0 10.3-7.1 8.0 -A
A2036.9 2.0 8.9 6.4 4.
138O5,4-9,66,39,9 3 ゞ°・0 °゛230°35) 1.2-0°04 to 20
0.18 0.11 - 1.24P
bO-12,411,054,3 Mg0 6.5 ---
Zn0 1・6
-Sample number 12345 Properties 5 Transition point 668 700 586 627 445 Softening point 840 880 700 780 595 Coefficient of thermal expansion 64.858.063.064.060.0 (XI
O() Thermal conductivity (x1o') 2.4 2.2 2.2 2.2 1
．． 9 The units of transition point and softening point are °C, and the unit of thermal expansion coefficient is 7.
The unit of °C1 thermal conductivity is cal 7cm, s, °C.

1 to 4 are those of the present invention, and 5 is a conventional example.

As can be seen from this table, the product of the present invention is extremely suitable for use in thermal heads.

The following types of glasses are particularly suitable for use in the present invention.

(1) S 102 , A1203BaO system (2)
ZnO-B2O3-8in2 system (3) P bo
S i02 B203 series (4) S iO□-
BaO-CaO system (5) S r ()2B a O
PbO system (6) PbO-ZnO-B2O3 system (7) 5I02-BaO-CaO-A403-B2
03 series (8) 5in2-B203-PbO-Al,
;03-CaO-MgO system (9) 8102 BaOPbOCaOA403-B2
O3 system

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a part of the general shape of the thermal head, and FIG. 2 is a cross-sectional view of FIG. 1 taken along the line A-A. DESCRIPTION OF SYMBOLS 1... Alumina substrate, 2... Glaze layer, 3... Resistance heating element, 4... Electrode lead, 5... Wear resistance layer.

Claims (1)

[Claims] 1. On a ceramic substrate containing 90 to 99.5% alumina, the material has a transition point of 550°C or higher, a softening point of 700°C or higher, and a thermal expansion coefficient of 45 to 70×10”-7. /C and the thermal conductivity is 1.8 to 2.8×10-”ca
A glaze substrate for a thermal head, which is formed by coating glass with l/crn, s, and c to form a glaze layer. 2. The glaze substrate for a thermal head according to claim 1, wherein the glass constituting the glaze layer has a transition point of 600°C. 3. The glaze substrate for a thermal head according to claim 1, wherein the glass constituting the glaze layer has a transition point of 650°C. 4. The glaze substrate for a thermal head according to claim 1, wherein the glass constituting the glaze layer has a softening point of 800°C. 5. The glaze substrate for a thermal head according to claim 1, wherein the glass constituting the glaze layer has a softening point of 820°C. 6 The glass constituting the glaze layer is 5iO2-BaO-
CaO-A1203-B203 glass, S t 02
-AJ! ! 20a BaO glass, SiO□-B2
03-PbO-A1203-CaO-MgO glass,
5iO2-BaO-PbO-CaO-A1203-B2
03 series glass, ZnOB2O38102 series glass, S
t 02-BaO-CaO glass, PbO-8iO
2-B203 series glass, P b OZ n OB 20
The glaze substrate for a thermal head according to claim 1, which is s-based glass or SiO□-BaO-PbO-based glass.