JP3455060B2 - Manufacturing method of thermal head - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a thermal head incorporated as a printer mechanism such as a word processor and a facsimile.

[0002]

2. Description of the Related Art Conventionally, a thermal head incorporated as a printer mechanism of a word processor or the like is nitrided so as to cover the entire upper surface thereof on a substrate 11 made of alumina ceramics having a glaze layer 12 as shown in FIG. And a reinforcing electrode 14, a heat generating resistor 15, an electrode layer 16 and a protective film 17 are respectively deposited on the nitride thin film 13 and the above-mentioned nitride thin film 13 is deposited based on a print signal. A predetermined electric power is applied to the electrode layer 16 to selectively cause the heating resistor 15 to generate Joule heat, and
The generated heat is conducted to the thermal recording medium to form a predetermined print image on the thermal recording medium, thereby functioning as a thermal head.

The glaze layer 12 is a heating resistor 1
The heat generated by No. 5 is accumulated and dissipated to maintain good thermal response characteristics of the thermal head, and is formed of a low heat conductive material such as glass or heat resistant resin.

Further, the nitride thin film 13 protects the glaze layer 12 so that the surface of the glaze layer 12 is not corroded by contact with an etching solution when the heating resistor 15 and the electrode layer 16 are finely processed by etching or the like. And is made of an inorganic material containing a nitrogen element such as Si ₃ N ₄ (silicon nitride) or SiAlON (sialon).

The reinforcing electrode 14 serves to electrically reinforce the electrode layer 16, and the reinforcing electrode 14 is electrically connected to the electrode layer 16 so that the electrode layer 1
6 prevents a large voltage drop from occurring.

Such a conventional thermal head is usually manufactured by the following manufacturing method. (1) First, the ceramic substrate 1 having the glaze layer 12
1 is prepared, and then a nitride thin film 13 is deposited on the entire upper surface of the substrate 11.

(2) Next, a predetermined conductive paste is printed and applied on the nitride thin film 13 by a conventionally known screen printing method or the like, and this is baked at a high temperature to form the reinforcing electrode 14. The conductive paste used at this time is a conductive component for imparting conductivity, a glass component as an adhesive, and an organic component (organic solvent, binder, etc.) for adjusting the viscosity of the paste and maintaining the outer shape. And Bi ₂ O ₃ (bismuth oxide) or PbO (lead oxide) was added as a kind of glass component in order to efficiently perform the baking operation of the paste at a low temperature. In addition, Bi ₂
The content of O ₃ or PbO was in the range of 10 to 15 wt% with respect to the total amount of the conductor component and the glass component in the conductive paste.

(3) Next, a resistive material such as TaN and a metallic material such as Al are sequentially deposited on the glaze layer 12 through the nitride thin film 13 by a thin film forming technique such as sputtering, and the coating is performed. The heat-generating resistor 13 and the electrode layer 16 are processed into a predetermined pattern by applying the well-known photolithography technique to the deposited TaN and Al, and finally S is formed on the heat-generating resistor 13 and the electrode layer 16.
The thermal head was completed by depositing the protective film 17 made of i ₃ N ₄ or the like by sputtering or the like.

[0009]

However, according to such a conventional method of manufacturing a thermal head, when the reinforcing electrode 14 is formed on the nitride thin film 13 by baking the conductive paste, it is included in the conductive paste. The large amount of Bi ₂ O ₃ or PbO present and the nitrogen component such as Si ₃ N ₄ forming the nitride thin film 13 violently react with each other to generate a large amount of gas (N ₂ ) near the interface between the _two. To do.
Therefore, many bubbles remain in the vicinity of the interface between the nitride thin film 13 and the reinforcing electrode 14, and the adhesion strength between the two is significantly reduced. When an external force is applied to the reinforcing electrode 14 by sliding contact of the thermal recording medium or the like, the reinforcing electrode 14 is peeled off from the nitride thin film 13 relatively easily, and the function as a thermal head is lost in a short time. It had the drawback of being.

[0010]

The present invention has been devised in view of the above-mentioned drawbacks, and a method of manufacturing a thermal head according to the present invention comprises forming a glaze layer in a strip shape on a ceramic substrate and at the same time the surface of the glaze layer. And a step of depositing a nitride thin film on the exposed surface of the ceramic substrate, and applying a conductive paste on the nitride thin film, and applying the conductive paste to the substrate 600 to 7
A step of baking at a temperature of 00 ° C. to form a reinforcing electrode,
A step of depositing a heating resistor and a common electrode on the nitride thin film so that a part of the common electrode extends onto the reinforcing electrode, wherein the conductive paste is a conductor component, When the content of Bi ₂ O _{3 and} the content of PbO with respect to the total amount of the conductor component and the glass component are represented by x wt% and y wt%, respectively, the x and y values are composed of a glass component and an organic component. Is in the internal area of the following coordinates A, B, C, and D in FIG. 1 (including on the line segment), however.

Coordinates A (0,8) B (7,0) C
(3,0) D (0,2) Further, the manufacturing method of the present invention comprises the steps of forming a glaze layer over substantially the entire upper surface of the ceramic substrate and depositing a nitride thin film on the surface of the glaze layer, Apply the conductive paste on the nitride thin film and
A step of baking at a temperature of 0 to 700 ° C. to form a reinforcing electrode, and a heating resistor and a common electrode on the nitride thin film,
A step of depositing a part of the common electrode so as to extend onto the reinforcing electrode, wherein the conductive paste comprises a conductor component, a glass component and an organic component, and the conductor component and Bi _{2 with} respect to the total amount of glass components
When the content of O ₃ is represented by x% by weight and the content of PbO is represented by y% by weight, the x and y values are the following coordinates A and B in FIG.
It is characterized in that it is in the internal area of C and D (including the line segment).

Coordinates A (0,8) B (7,0) C
(3,0) D (0,2)

[0013]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below in detail with reference to the accompanying drawings. 1 is an xy graph showing the contents of Bi ₂ O ₃ and PbO in the conductive paste according to the manufacturing method of the present invention, FIG. 2 is a perspective view of a thermal head manufactured according to one embodiment of the present invention, and FIG. FIG. 6 is a sectional view taken along line XX of FIG.
1 is a ceramic substrate, 2 is a glaze layer, 3 is a nitride thin film, 4 is a reinforcing electrode, 5 is a heating resistor, 6 is an individual electrode, 7
Is a common electrode (electrode layer), and 8 is a protective film.

The thermal head shown in FIG. 1 has a glaze layer 2 on a ceramic substrate 1 made of alumina ceramics.
Nitride thin film 3, reinforcing electrode 4, heating resistor 5, individual electrode 6
And the common electrode 7 and the like are adhered respectively.

The glaze layer 2 is applied on the upper surface of the ceramic substrate 1 so as to have an arcuate cross section (width W: 0.5 mm to 1.0 mm, thickness T: 22 μm to 55 μm), and is made of glass or heat-resistant material. It is made of a low heat conductive material such as a conductive resin and accumulates the heat generated by the heat generating resistor 5 to an appropriate temperature to keep the thermal response characteristics of the thermal head good.

The nitride thin film 3 has a glaze layer 2
Over the entire upper surface of the ceramic substrate 1 on which the film is formed.
Deposited with a thickness of 05-0.4 μm
_The glaze layer 2 is formed of an inorganic material containing a nitrogen element such as ₃ N ₄ (silicon nitride) or SiAlON (sialon), and is used when the heating resistor 5, the individual electrode 6 and the common electrode 7 described later are finely processed by etching or the like. This effectively prevents the surface of the substrate from being corroded by contact with the etching solution.

The reinforcing electrode 4 is deposited on the nitride thin film 3 with a thickness of 15 μm to 32 μm, is made of, for example, silver, and is electrically connected to a common electrode 7 which will be described later. 7 is allowed to flow a large current. The reinforcing electrode 4 contains PbO and Bi ₂ O ₃ in a predetermined ratio. More specifically, the content of Bi ₂ O ₃ and PbO is such that, when the content of Bi ₂ O ₃ is represented by x wt% and the content of PbO is represented by y wt%, the x and y values are as shown in FIG. Xy
In the graph, it is located in the internal area of coordinates A, B, C, and D below (including on the line segment).

Coordinates A (0,8) B (7,0) C
(3,0) D (0,2) Further, a plurality of the heating resistors 5 are deposited and arranged near the top of the glaze layer 2 with the nitride thin film 3 interposed therebetween.
Since it is made of a resistance material such as N, TaSiO ₂ or the like, when electric power from an external power source is applied through the individual electrode 6 and the common electrode 7 which will be described later, Joule heat is generated and it is necessary to form a printed image. Predetermined temperature, for example 200
It exotherms to a temperature of ℃ ~ 350 ℃.

The individual electrode 6 and the common electrode 7 are connected to both ends of each heating resistor 5, and the electrodes 6 and 7 apply electric power from an external power source to the heating resistor 5. ing. A part of the common electrode 7 extends to above the reinforcing electrode 4 and is electrically connected to the reinforcing electrode 4 at the extending portion.

Then, the heating resistor 5 and the common electrode 7
And the like are covered with a protective film 8 made of SiO ₂ (silicon oxide) or Si ₃ N ₄ , whereby the heating resistor 5 and the like are oxidatively corroded by the contact of moisture contained in the atmosphere and slidingly contacted with the thermal recording medium. It is designed to protect against wear.

In such a thermal head, a predetermined electric power is applied between the individual electrode 6 and the common electrode 7 in response to a print signal to selectively cause the heating resistor 5 to generate Joule heat, and the generated heat is thermally recorded. It functions as a thermal head by conducting it to a medium and forming a predetermined print image on the thermal recording medium.

Next, a method of manufacturing the above-mentioned thermal head will be described with reference to FIGS.

(1) First, as shown in FIG. 4A, a glaze layer 2 is formed in a strip shape on a ceramic substrate 1, and then, as shown in FIG.
As shown in (b), a nitride thin film 3 is deposited on the surface of the glaze layer 2 and the exposed surface of the ceramic substrate 1.

The ceramic substrate 1 is made of Al ₂ O ₃ , S
A ceramic green sheet is formed by adding a suitable organic solvent or solvent to a ceramic raw material powder such as iO ₂ or MgO to form a slurry, and adopting a conventionally known doctor blade method or calender roll method. After that, the ceramic green sheet is punched into a predetermined shape and fired at a high temperature, and a predetermined glass paste is printed on a predetermined area of the upper surface of the ceramic substrate 1 by a conventionally known screen printing method or the like. Apply and then paste the paste to about 10
The glaze layer 2 is deposited on the ceramic substrate 1 by baking at a high temperature of 00 ° C to 1200 ° C.

The nitride thin film 3 is made of Si ₃ N ₄ , S
It is formed by depositing iAlON, SiON or the like on the surface of the glaze layer 2 and the exposed surface of the ceramic substrate 1 to a thickness of 0.05 to 0.4 μm by a conventionally known sputtering method or the like.

(2) Next, as shown in FIG. 4C, a predetermined conductive paste is applied onto the nitride thin film 3 and the paste is baked to form the reinforcing electrode 4.

Examples of such conductive paste include conductor components (Au, Ag, Cu, etc.) and glass components (SiO ₂ , B).
₂ O ₃ , PbO, etc.) and an organic component (organic solvent, binder, etc.) are mixed in a predetermined ratio, and the content of Bi ₂ O ₃ with respect to the total amount of the conductor component and the glass component is x% by weight, PbO. When the content rate of y is represented by y% by weight, the above x,
In the xy graph of FIG. 1, the y value is represented by the following coordinates A, B, C,
The conductive paste located in the internal area of D (including the line segment) is used.

Coordinates A (0,8) B (7,0) C
(3,0) D (0,2) The conductive paste is printed and applied on the nitride thin film 3 by a conventionally known screen printing method to a thickness of, for example, 25 to 58 μm, and then the applied paste is applied to 60
By baking at 0 to 700 ° C., the reinforcing electrode 4 is deposited on the nitride thin film 3.

When the reinforcing electrode 4 is formed as described above, gas (N) is formed near the interface between the nitride thin film 3 and the reinforcing electrode 4.
₂ ) hardly occurs, and both can be adhered extremely firmly. Therefore, even if an external force is applied to the reinforcing electrode 4 by sliding contact of the thermosensitive recording medium or the like, the reinforcing electrode 4 is not easily peeled off from the nitride thin film 3, and the thermal head is kept in a good state for a long period of time. Can be operated.

The operation and effect of the present invention will be described with reference to Table 1.

[0031]

[Table 1]

Table 1 shows that 24 experimental samples (Nos. 1 to 24) for measuring adhesion strength were prepared and Si ₃ N _{4 of} each sample was prepared.
The adhesion strength between the thin film and the conductive film was measured by the 0.6φ annealed copper wire vertical bending peel test, and after the measurement, each sample was further heat-aged at 150 ° C. for 1000 hours, and the same peel test was performed. Shows the result of measuring the adhesion strength again, and the adhesion strength was comprehensively evaluated in three grades of ◯ Δx. ◯ indicates that sufficient adhesion was obtained, Δ indicates that the adhesion strength was low, and x indicates that the adhesion strength was extremely low. The 24 samples used for this measurement were Al ₂ O having a glaze layer.
_{3 A} Si ₃ N ₄ thin film was deposited on the upper surface of the substrate by a sputtering method to a thickness of 0.1 μm, and Bi ₂ O ₃ , P
While applying 24 kinds of conductive pastes with different bO contents by screen printing,
These are obtained by forming a conductive film by baking these at a temperature of 630 ° C. In addition, Bi ₂ O described in Table 1
_{The 3} content x is the content of Bi ₂ O ₃ with respect to the total amount of the conductor component and the glass component in the conductive paste, and the PbO content y is the content of PbO with respect to the total amount of the conductor component and the glass component in the conductive paste. The contents are expressed in% by weight.

According to such measurement results, Bi ₂ O ₃ and P
bO content (x, y) is (0,15), (0,10), (0,1),
(0,0.5), (15,0), (10,0), (1,0), (0.5,0), (1,1)
, (1,8), (5,3) sample No.1, No.2, No.
6, No.7, No.8, No.9, No.13, No.14, No.15, No.20
, No. 24, sufficient adhesion strength could not be obtained between the Si ₃ N ₄ thin film and the conductive film, whereas the above content (x,
y) in the xy graph of FIG. 1 with the following coordinates A, B, C,
Sample No.3, No.4, No.5, No.10, No.11, No.12, No.1 located in the internal area of D (including the line segment)
6, No.17, No.18, No.19, No.21, No.22, No.23
Then, it can be seen that the adhesion strength between the Si ₃ N ₄ thin film and the conductive film was extremely high.

Coordinates A (0,8) B (7,0) C
(3,0) D (0,2) Here, to analyze the factor of a sample in which the adhesion strength between the Si ₃ N ₄ thin film and the conductive film was extremely low, Bi
Sample No. 6, No. 7, PbO in which the ₂ O ₃ content x was set to 0% by weight and the PbO content y was set to less than 2% by weight
Samples No. 13, No. 14 and Bi ₂ O ₃ content x and PbO content y each set to 1 wt% with the content y set to 0 wt% and the Bi ₂ O ₃ content x set to less than 3 wt%. In Sample No. 15 set to%, it was found that the glass component was not sufficiently softened during the baking, and the baking of the conductive film was incomplete. Samples No. 1, No. 2 and Bi ₂ O with PbO content y set to be higher than 8% by weight
₃ Sample N with content x set to be greater than 7% by weight
o.8, No.9, Bi ₂ O ₃ content x x 1 wt%, Pb
Sample No. 20 with O content y set to 8 wt% and Bi ₂ O ₃ content x set to 5 wt% and Sample No. 24 set PbO content y to 3 wt% had PbO or Bi ₂ O ₃ and the nitrogen component in the underlying Si ₃ N ₄ thin film violently react with each other to generate a large amount of gas (N ₂ ) near the interface between the two, and the interface between the Si ₃ N ₄ thin film and the conductive film. It was found that many bubbles remained in the vicinity.

Therefore, the content x (wt%) of Bi ₂ O _{3 and} the content y (wt%) of PbO with respect to the total amount of the conductor component and the glass component in the conductive paste are shown by the following coordinates A and B in FIG. , C, D must be set so as to be located in the internal area (including the line segment).

Coordinates A (0,8) B (7,0) C
(3,0) D (0,2) In the above experiment, the conductive paste was baked at a temperature of 630 ° C. to form a conductive film.
0 Below the ° C., are not glass components is sufficiently softened in the conductive paste, baking might serve as incomplete, also more than 700 ° C. When the conductive PbO and Bi ₂ contained in the paste O ₃ and the nitrogen component in the nitride thin film 3 violently react with each other, and a large amount of gas (N ₂ ) is generated near the interface between them, so that the nitride thin film 3 and the reinforcing electrode 4
The adhesion strength with may be weakened. Therefore, the baking temperature of the conductive paste must be set within the range of 600 to 700 ° C.

(3) Finally, as shown in FIG. 4D, the heating resistor 5, the individual electrode 6 and the common electrode 7 are provided on the glaze layer 2 on which the nitride thin film 3 is deposited. Are deposited so as to extend onto the reinforcing electrode 4, and these are further covered with a protective film 8.

The heating resistor 5, the individual electrode 6 and the common electrode 7 are formed by applying the well-known sputtering method and photolithography technique to the glaze layer 2,
It is partially deposited on the reinforcing electrode 4 and the like via the nitride thin film 3, and specifically, TaN and Al are given a predetermined thickness by a sputtering method or the like (TaN has a thickness of 0.01 to 0.5 μm, Al is deposited to a thickness of 0.5 μm to 2.0 μm), and thereafter, photolithography technology is adopted, and T
It is deposited by processing aN and Al into a predetermined pattern.

The protective film 8 is made of SiO ₂ , Si ₃ N
₄ or the like is deposited on the heating resistor 5 or the like to a thickness of 3.5 to 13.5 μm by a conventionally known sputtering method or the like,
A thermal head as a product is completed by covering the heating resistor 5 and the like with the protective film 8.

The present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the gist of the present invention. For example, in the above-described embodiments, the present invention is applicable. The manufacturing method described above was applied to the case of manufacturing a partial glaze type thermal head in which the glaze layer 2 is partially formed on the ceramic substrate 1, but instead of this, a glaze layer 2'as shown in FIG. It may be applied when manufacturing a full-glaze type thermal head formed on substantially the entire upper surface of the substrate 1. In this case, instead of the “step of partially forming the glaze layer 2 on the upper surface of the ceramic substrate 1 and depositing the nitride thin film on the surface of the glaze layer 2 and the exposed surface of the ceramic substrate 1” in the above-described embodiment, , "The step of forming the glaze layer 2'on almost the entire upper surface of the ceramic substrate 1 and depositing the nitride thin film 3 on the surface of the glaze layer 2 '" is required.

[0041]

According to the manufacturing method of the present invention, when the reinforcing electrode is formed on the nitride thin film by baking the conductive paste, gas is hardly generated in the vicinity of the interface between the nitride thin film and the reinforcing electrode. Both can be adhered extremely firmly. Therefore, even if an external force is applied to the reinforcing electrode due to sliding contact of the thermosensitive recording medium, the reinforcing electrode does not easily peel off from the nitride thin film, and the thermal head can function in a good state for a long period of time. You can

[Brief description of drawings]

FIG. 1 Bi ₂ in a conductive paste according to the manufacturing method of the present invention
O _3, an xy graph showing the content of PbO.

FIG. 2 is a perspective view of a thermal head manufactured by the manufacturing method of the present invention.

3 is a cross-sectional view taken along line XX of FIG.

4 (a) to 4 (d) are cross-sectional views in each step for explaining the manufacturing method of the present invention.

FIG. 5 is a cross-sectional view of a thermal head manufactured by another embodiment of the manufacturing method of the present invention.

FIG. 6 is a sectional view of a conventional thermal head.

[Explanation of symbols]

1 ... Ceramic substrate 2 ... Glaze layer 3 ... Nitride thin film 4 ... Reinforcing electrode 5: Heating resistor 6 ... Individual electrodes 7 ... Common electrode 8 ... Protective film

Claims (2)

(57) [Claims] 1. A step of forming a glaze layer in the form of a strip on a ceramic substrate and depositing a nitride thin film on the surface of the glaze layer and the exposed surface of the ceramic substrate, and applying a conductive paste on the nitride thin film. With
A step of baking this at a temperature of 600 to 700 ° C. to form a reinforcing electrode; and a heating resistor and a common electrode on the nitride thin film so that a part of the common electrode extends to above the reinforcing electrode. And a step of depositing the conductive paste, wherein the conductive paste is composed of a conductor component, a glass component and an organic component, and the content of Bi ₂ O ₃ is x wt% with respect to the total amount of the conductor component and the glass component. , When the PbO content is represented by y% by weight, the x and y values are the internal regions of the following coordinates A, B, C and D in FIG. 1 (including the line segment).
1. A method of manufacturing a thermal head, comprising: Coordinates A (0,8) B (7,0) C (3,0) D
(0,2) 2. A step of forming a glaze layer over substantially the entire upper surface of a ceramic substrate and depositing a nitride thin film on the surface of the glaze layer; and applying a conductive paste on the nitride thin film,
A step of baking this at a temperature of 600 to 700 ° C. to form a reinforcing electrode; and a heating resistor and a common electrode on the nitride thin film so that a part of the common electrode extends to above the reinforcing electrode. And a step of depositing the conductive paste, wherein the conductive paste is composed of a conductor component, a glass component and an organic component, and the content of Bi ₂ O ₃ is x wt% with respect to the total amount of the conductor component and the glass component. , When the PbO content is represented by y% by weight, the x and y values are the internal regions of the following coordinates A, B, C and D in FIG. 1 (including the line segment).
1. A method of manufacturing a thermal head, comprising: Coordinates A (0,8) B (7,0) C (3,0) D
(0,2)