JPS60151071A - thermal head - 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 The present invention relates to a method of forming a heating element for a thermal head.

Currently, impact printers and non-impact printers are used as printer devices. Impact printers currently account for a large portion of the printer market, but due to noise during printing, they are gradually being replaced by non-impact printers. Among non-impact printers, discharge rupture inkjet printers, thermal printers, and other printers are currently in use, but in recent years, thermal printers have dominated the market because they are easier to maintain, smaller, lighter, and faster. The proportion is increasing.

Here, we will describe the manufacturing process of the thermal head used in the heat-sensitive method.

Usually, an alumina substrate is used as the base substrate for the thermal head because of its good thermal conductivity. If a heating resistor is formed directly on an alumina substrate, the energy required to raise the temperature of the heating resistor to a predetermined temperature will be large due to its good heat dissipation properties. A layer is formed. When the glaze layer becomes thicker, the temperature of the resistor rises more easily, but the heat dissipation characteristics deteriorate, and if the printed characters smear or are too large, they can be printed even when the head is in the off state. Furthermore, if the glaze layer is too thin, the amount of energy required for printing increases, which determines the optimum value for the glaze layer.

Usually, a resistive heating element is formed on this substrate by sputtering. The heating element is Ta2N.

T a-5i 02, T a-8i, etc. are used. Next, 0r-Au, which will become the lead wires of the heating element, is formed on the heating element by vapor deposition, and etched into a predetermined pattern using a photoresist method. I do. Then apply 8102 protective film to prevent thermal oxidation of the heating element.

A Ta2011 protective film for improving the wear resistance of the head is formed by sputtering to produce a thermal head. As described above, many vacuum processes are involved in the thermal head manufacturing process, making it difficult to reduce costs.

The present inventors have already discovered that the electroless N1-W-P coating is excellent as a heating resistor for a thermal head.

This was aimed at significantly reducing the cost of the thermal head by replacing the heating resistor with a wet plating method and eliminating some of the vacuum process.

However, this N1-W-P coating had poor adhesion to the glaze layer and the alumina substrate, and could not be put to practical use as it was.

The present invention is characterized in that a metal oxide film is formed on the substrate in order to increase the adhesion strength of this N1-W-P film.

Next, the manufacturing process of this thermal head will be described.

'Ii'02 is formed by forming a 5n02 film on a glazed alumina substrate by OVD, or by immersing a glazed alumina substrate in a solution containing an organometallic compound and firing.

A metal oxide film such as 5nO1, 'ra, o, etc. is formed. The firing temperature is desirably 200°C to below the softening point of Daleze. If the temperature is 200° C. or lower, the reaction of dehydration condensation after hydrolysis of the organometallic compound does not occur, making it difficult to obtain a uniform and strong metal oxide film. Further, when heated above the softening point of the glaze layer, the glaze layer is deformed. Film thickness is 1
A value of 0 to 1000 is appropriate. If the film thickness is less than 1 [IX, the adhesion strength will be poor, and if a filter that forms a metal oxide film of 2000X or more is applied all at once using the OVD method or dipping method, the film will easily crack and the adhesion strength will deteriorate. This is because you will not be able to raise it.

The substrate thus obtained is subjected to a conventional electroless plating pretreatment process. This is a sensitizing process in which divalent tin ions are adsorbed onto the surface of the substrate by immersing it in an acidic solution of stannous chloride in hydrochloric acid, and after rinsing the substrate with pure water, it is immersed in an acidic solution of palladium chloride in hydrochloric acid. This is an activating process in which palladium, which becomes the catalyst nucleus for electroless plating, is adsorbed. In the activating process, S n2+ -1-P (L”+ →P d' +S
This means that a reaction called n'+ occurs on the surface of the substrate.

After this, by electroless plating, Ni is the main component and P: 3
-10w/. , W: 1~so''10-containing 1tylf[ is formed by electroless plating. On this N1-W-P film, 2μ of N 1- Or -Au is normally formed as a lead terminal by vapor deposition.

A negative resist is applied on top of this by a roll coater method, an alkaline dipping method, a spinner method, etc.
1A, only the part that will become the heating element of 9 is exposed in a predetermined pattern, and after dissolving and removing unnecessary parts of the resist, Ni-0r is applied.
- Perform Au etching. After that, a positive resist was applied in the same manner, exposed to light in a predetermined pattern, and unnecessary portions of the resist were dissolved and removed, followed by Ni-Or-Au, Ni-W.
- Etch P. As a result, ten lead terminal portions are formed.

When 5nO6 (transparent conductive film) is used as the metal oxide film, this underlayer is etched using a redox system. For example, 0rOt3 ・6H20
After dissolving 100f in 1 t of 20% hydrochloric acid solution, heating to 60°C, using a carbon electrode with a surface area of 20 ct/l,
Apply current of 0A/d-. By this, ○r3 in the solution
+ is reduced to Or” 10. After 30 minutes of electricity,
The substrate with herecyst is immersed in this solution. After soaking for 60 seconds to 1 minute, the 5n02 is completely etched.

The immersion time depends on the film thickness of SnO. The reaction at this time is as follows.

SnO, +20r"++ 2H1-+ 5nO-)2O
r”+H2O5nO-1-2HO4-+ 5nO42+
H20 Unnecessary resist was dissolved and removed from the thus obtained substrate, washed, dried, and sputtered to form SiO21 to 3 μm thick as an oxidation protective film for the heating element and Ta2O2 μm thick as a wear-resistant protective film. This completes the thermal head.

The adhesion strength of the N1-W-P plating film obtained by this method was 100 f//wn or more, which poses no problem in practical use.

Next, a detailed explanation will be given using "Execution 1".

Implementation F! 1IJ1 A 400× thick SnO 2 film was formed using OVD on a substrate in which high melting point glass was formed as a glaze layer with a thickness of 50 μm on an aluminum oxide plate. After cleaning this substrate, it is immersed for 1 minute in a solution of stannous chloride i y7t and hydrochloric acid 1 cr/l. After immersion, it was washed with water, immersed for 1 minute in a 5-fold diluted solution of Red Schumer manufactured by Nippon Kanigen Co., Ltd. After washing with water, it was immersed in a plating bath of 80° C. having the following composition for 4 minutes.

As a result, an N1-W-P plating film having a film thickness of 3 oooX and a specific resistance of 150 μΩm was obtained. After washing and drying this substrate, about 2 μm of Ni-Or-Au was deposited by regular vapor deposition. A predetermined pattern is formed using a negative resist and a positive resist. Thereafter, the SnO2 between the lead terminals is etched using a redox-based etching solution of Or"10r3+.The surface area of the carbon electrode in the solution is 60ca, and the surface area of the carbon electrode in the solution is 10A.
/dJ for 30 minutes. Among these Q this board is 60
Immersed for seconds. This eliminates unnecessary S on the alumina substrate.
nO□ was completely dissolved.

Next, the positive resist and negative resist were dissolved with the stripping solution, washed, and dried. Thereafter, a thermal head was fabricated by sputtering to form a heat-resistant oxidation protective film of 5102 of 2 μm and a wear-resistant protective film of Ta2O of 5 μm. Is the adhesion strength of the lead terminal part of this thermal head 1Q5? There were no problems beyond practical use.

The results of the dynamic characteristic test of this thermal head are shown in FIG.

Dynamic characteristics is a test in which voltage is sequentially applied to a heating element until the heating element is destroyed, and its lifespan is estimated based on the wattage.

12 in FIG. 3 is the dynamic characteristic of the heating element for a thermal head of the present invention, and 11 is the dynamic characteristic of the conventional Ta2N heating element, indicating that the heating element of the present invention can withstand higher heat generation conditions. I understand.

Implementation row 2 A substrate on which high-melting point glass was formed as a glaze layer every 50μ thick on an aluminum oxide plate was immersed in a mixed solution, pulled up at a constant speed of 50-/-, and then It was baked at 500°C for 1 hour.

After that, N1-W-P plating was performed in the same manner as in υ1 to produce a thermal head. The adhesion strength of the lead terminal portion of this thermal head was 909/rran, which was not a problem in practical use.

The results of the dynamic characteristic test were also similar.

Example 3 A substrate in which a high melting point glass was formed as a glaze layer with a thickness of 30 μm on an aluminum oxide plate was immersed in a mixed solution, pulled up at a constant speed of 15 cm/1 titrr, and then heated at 500°C. Baked for 1 hour. As a result, a Ta205 film having a thickness of 500 mm was obtained. After that, N1-W-P plating was performed in the same manner as in Example 1 to produce a thermal head. The adhesion strength of the lead terminal portion of this thermal head was 100 f/mm, which was not a problem in practical use. The results of the dynamic characteristic test were also similar.

Example 4 A SnO2 film with a thickness of 300 μm was formed using avD on a substrate in which high-melting point glass was formed as a glaze layer with a thickness of 50 μm on an aluminum oxide plate. After cleaning this substrate, a predetermined electroless plating pretreatment step was performed, and the substrate was immersed in a plating bath having the following composition at 80° C. for 5 minutes.

As a result, an N1-W-P plating film having a film thickness of 3 oooX and a specific resistance of 160 μΩm was obtained.

Regarding this dynamic characteristic, results similar to those obtained in the experiment Jl were obtained.

When a thermal head was manufactured using the resistance heating elements obtained by the methods of Examples 1 to 4 and actual printing was performed, it was found that printing on the lower line or higher was possible.

From the above, it was found that the thermal head of the present invention has a lifespan that is long enough to be put into practical use.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the thermal head of the present invention. 1... Ceramic substrate 2... Glaze layer 6... Metal oxide layer 4... Electroless Nickel plating film 5...
...... Lead wire 6 ... Oxidation-resistant protective film 7 ... Wear-resistant protective film Figure 2, How to make the thermal head of the present invention 8・・・・・・
...Resist part 9 ...Heating element part 10 ... Lead wire Figure 3, dynamic characteristic test results 11 ... Dynamic characteristics of Ta and N 12・・・
...Dynamic characteristics of the thermal head of the present invention Applicant Suwa Seikosha Co., Ltd. Agent Patent attorney Yo Mogami

Claims (1)

[Claims] A glaze layer 2 is formed on a smooth substrate 1 with good thermal conductivity, and after forming a metal oxide film on this, a normal electroless plating pretreatment is performed, and the substrate is immersed in an electroless plating bath. By doing so, an electroless plating film 4 is formed on the surface, and a lead wire 5. is formed by a predetermined method. Oxidation-resistant protective film6. A thermal head characterized in that a wear-resistant insurance film 7 is formed.