JPS62201265A - Membrane type thermal head - Google Patents

Abstract

PURPOSE:To obtain a membrane type thermal head having high heat resistance, long life and high inherent resistivity and adjustable in temp. coefficient, by providing a heat generating resistor membrane based on a high m.p. metal, aluminum and nitrogen to substrate having a heat insulating layer and forming an abrasion resistant protective film on the surface thereof and, further connecting a power supply electrode to said resistor membrane. CONSTITUTION:A glaze layer 2 is formed to the surface of a glazed ceramic substrate 1. The glaze layer 2 comprises oxide corresponding to the glaze of porcelain and contains silicon oxide and aluminum oxide. A membrane heat generating resistor 3 is formed on the glaze layer 2 in a film form and a power supply electrode 4 is further formed in a film form and, at last, an abrasion resistance protective film (e.g., an Al-O-N system, an Al-O system, an Al-Si-O system) 6 is formed in a film form. The heat generating resistor 3 is an oxide containing aluminum and a high m.p. metal (at least one of Ti, Mo, W, Hf, Ni, V, Zr, La, Cr, Ta, Fe and Co). This high m.p. metal is used alone or in combination thereof and largely varies in the resistivity range of 10<7>-10<2>muOMEGAcm of the heat generating resistor in both cases.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a thin film thermal head, and more particularly to a thin film thermal head having an improved thin film heating resistor.

[Prior Art and its Problems] Thin-film thermal heads using thin-film heating resistors are widely used as print heads in computers, word processors, facsimile machines, and the like. The thermal head has a large number of resistive heating element dots arranged, and selectively energizes them to generate heat in a desired pattern or character shape, thereby thermally transferring the color material of the printing ribbon to the paper surface. Various resistance heating elements are known or used, but the most commonly used material is Ni.
-Cr, Ta2N, Ta-8i02, cr-s
There are i etc.

Although these have excellent properties as resistance heating elements for thermal heads, they also have various drawbacks. Metal-based heating resistors such as alloys have poor heat resistance and oxidation resistance, and when the energy required for printing is repeatedly applied, oxidation occurs in the heating resistor due to heat generation, causing an increase in resistance value. This may lead to deterioration of printing characteristics.

In addition, these metal heating resistors undergo large thermal expansion and contraction when placed under rapid thermal cycles due to heat pulses caused by repeated energization, creating large stress between the underlying substrate and the surface wear-resistant protective film. It causes the cow to crank. on the other hand,
In the case of oxides and nitrides such as Ta5i02, their thermal conductivity is low, so they lack heat uniformity within the heating element, resulting in a decrease in printing quality.

In addition, metal-based heating resistors have a small specific resistivity, and the compound-based heating resistors mentioned above also have a small specific resistance (T
200 to 300 μΩcm for a2N, approximately 2000 μΩcm for Ta-3i02>, and in order to obtain the sheet resistance of around 1 difference/m2 required for 4 normal heads, it is necessary to realize a heating resistor of tens of thin films, which is unstable. difficult to manufacture. The curved manufacturing method is a well-known semiconductor process technology such as sputtering, ion blasting, or CVD, but it is difficult to control the process unless the film thickness is about 1,000. Furthermore, the temperature coefficient of resistance of these heating elements is relatively insensitive to the component ratio, and it is difficult to control them to a desired value. Furthermore, in the case of a metal type, a reaction occurs between the heating element and the power supply electrode, which causes defects such as fluctuations in the resistance value of the heating resistor and disconnection.

[Objective of the Invention] Therefore, the object of the present invention is to provide a material with high heat resistance, long life, and
An object of the present invention is to provide a thin film type thermal head using a thin film heating resistor having a large specific resistivity and an adjustable temperature coefficient.

[Summary of the Invention] The present invention is characterized in that a thin film heating resistor contains a high melting point metal, aluminum, and nitrogen as main components. That is, it is an M-Al2-N heating resistor. Here H is a high melting point metal, 11, No, w 1tH
, Ni, V, Zr, 1-alTa, Fe1C
It is at least one selected from o and Cr.

Due to the presence of the high melting point metal, the resistivity of the heating element does not change over a long period of time even with repeated heat pulses, resulting in a stable thermal head. Also, unlike metal-based materials, since it is an oxy-nitride, thermal expansion and contraction are small, and large internal stress due to the difference in thermal expansion coefficient between the upper and lower layers does not occur, and cracks do not occur.

Increasing the subsidence of metal or AlN improves thermal conductivity, improves heat uniformity, and improves power efficiency as a thermal head. Further, due to the presence of sufficient oxygen, the properties are stabilized without fear of oxidation over time.

Furthermore, since the specific resistivity changes greatly depending on the content of high melting point metal, controlling the content increases the control range of the characteristics of the thermal head.
It is also possible to easily design a heating element resistance such as Ωcm resistance temperature coefficient ±1100 pI)/'C. With such a high resistivity, the thin film of the heating element should preferably have a thickness of around 1000.
Film formation becomes easy.

[Detailed Description of the Invention] The outline of the structure of the thin film type thermal head of the present invention is shown in FIG. In the figure, 1 is a glazed ceramic substrate, on the surface of which a glazed layer 2 is formed. The glaze layer 2 is an oxide corresponding to a porcelain glaze, and contains oxides of silicon and aluminum, and more preferably also contains the same high melting point metal used in the heating resistor-4 integral layer.

A thin film resistance heating element 3 of the present invention is formed on the glaze layer 2 by, for example, a known sputtering method, and a power supply electrode (formerly made of Cr, Al, etc., especially Al) 4 is formed by vapor deposition or sputtering. Finally, a known wear-resistant protective film (e.g. A2-0-N system, Al-0 system, Al1-3 system) is applied.
(i-0 series, etc.) 6 is formed by sputtering or the like.

According to the present invention, the heating resistor 3 is made of aluminum and a high melting point metal M (Ti, No, W, Hf, Ni, V
, Zr1La, Cr1Ta, and Fe1Co). These high melting point metals have different effects depending on the type, but regardless of whether they are used alone or in any combination, the resistivity of the heating resistor is 107 to 1.
It fluctuates greatly within the range of 0.02 μΩcm. Furthermore, by selecting a specific high-melting point metal, it is possible to design a heating element with a desired resistivity and temperature coefficient. For example, resistivity 104μΩc
If m is selected, the film thickness can be 1000 Å or more. Generally, the high melting point metal can be selected in a range of 20 to 60 wt%. This point will be specifically illustrated in Examples.

AN can form a heat-resistant and acid-resistant nitride, and by changing the ratio, it is possible to maintain heat resistance and change the resistivity. For example, drunkenness N has a resistivity of >>1
07μΩcm, temperature coefficient -1500ppm/°C
However, when the content of the high melting point metal M is 10W1% or more, it is possible to obtain a value of 107 μΩcm or less and −100 ppm/°C or more.

It is preferable to select a wear-resistant protective layer 6 containing at least two of H, Al, and H, since the heating resistor of the present invention will fit well into the wear-resistant protective layer and the difference in thermal expansion coefficient will be reduced. Furthermore, it is preferable to use A12 for the electrodes 4 and 5, as this also improves the fit between the electrodes and the heating resistor.

The heating resistor of the present invention can be manufactured particularly by a sputtering method. For example, solid powder having a desired composition ratio is produced in advance, compression molded to form pellets 1 to 1, and this is used as a target using Ar as a sputtering gas, with N2 gas etc. coexisting as necessary. Ions are bombarded with a target, and the released ions or atoms are deposited on a substrate. The film composition can be adjusted by changing the pellet composition and sputtering conditions.

Example composition 14oA. , 23 NO, 45 pellets were used as the sputtering gas, Ar of 1 to 6 mTorr was used as the sputtering gas, and the target-substrate distance was 60 #, R.
[Power 1~10W/cnF, substrate temperature 200~40
A heating resistor having the above composition was manufactured by adjusting the 0°C conditions, and a thermal head was created by roughly forming an Al electrode and a protective film in this order.

Note that the substrate surface layer and the protective layer contain N in addition to Al and Si.
Contains a small amount of o. The following tests were conducted on the obtained thermal head.

Figure 2 shows the rate of change in resistance when a heat pulse with a pulse width of 0.3 msec and a period of 2 msec was applied to a sample with x = 0.32. Further, the resistivity and temperature coefficient of resistance depending on the No content are shown in FIG. As control samples, the results of heat resistance pulse testing for a conventional Ta2N heating resistor A and a Zr-8i heating resistor C are also shown in FIG. B in FIG. 2 shows a thermal head using a heating resistor according to the present invention.

[Function and Effect] As can be seen from Fig. 2, the thermal head using the to-Al-N non-heating resistor B of the present invention does not change its resistance value even when a large number of heat pulses are applied, and its heat resistance deteriorates. . When a certain number of heat pulses are exceeded in conventional heating resistors A (Ta2N) and C (Zr-3i), the change in resistance becomes large.

As can be seen from FIG. 3, the resistivity and temperature coefficient of resistance of the heating resistor of the present invention vary greatly depending on the content of the high melting point metal. Therefore, these values can be designed to desired values by adjusting the content of the high melting point metal.

The improvement in heat resistance is thought to be due to the uniformity of the temperature distribution within the plane of the heating element and the reduction in the coefficient of thermal expansion.

Furthermore, since the heating element contains ^l, even if the AI2 electrode is used, there is no fear that it will diffuse into the heating element, and therefore an inexpensive Al electrode can be used for power supply. In addition, if a material containing Mo, Al, and N is used for the wear-resistant protective film, the mutual compatibility will be improved, the adhesion will be improved, and it will be resistant to thermal shock, etc., and the occurrence of cracks and peeling will be suppressed. Ru. Further, the heating resistor of the present invention has excellent chemical resistance and is hardly affected by alkali or moisture.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the structure of a thermal head, FIG. 2 is a graph showing a heat resistance test of a thermal head using the heating resistor of the present invention and a conventional example, and FIG. 3 is a graph showing heat generation in the thermal head of the present invention. It is a graph showing the relationship between a high melting point metal contained in a resistor, resistivity, and resistance temperature coefficient.

Claims (1)

[Claims] 1. A heat generating resistor thin film containing a high melting point metal, aluminum and nitrogen as main components is provided on a base substrate having a heat insulating layer,
A thin film type thermal head, which has a wear-resistant protective film formed on its surface, and further has a power supply electrode connected to the resistor. 2. High melting point metal is Ti, Mo, W, Hf, Ni, V, Z
2. The thermal head according to item 1, which is selected from the group consisting of r, La, Cr, Ta, Fe, and Co. 3. The first wear-resistant protective film contains at least two elements selected from nitrogen, aluminum, and a high melting point metal.
Thermal head described in section. 4. The thermal head according to any one of items 1 to 3 above, wherein the power supply electrode is an Al single layer.