JP2001113741A - Thermal printing head and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal printing head enhancing printing quality and eliminating other thermal problem by a substrate material high in radiatioan effect. SOLUTION: In a thermal printing head A, a heat accumulating glaze layer 11 is formed on a substrate 10, and electrode patterns 12, 13, a heating resistor 14 and a protective layer 15 are formed on the heat accumulating glaze layer 11. A ceramics substrate comprising aluminum nitride excellent in heat conductivity is used as the substrate 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal print head used for printing by, for example, a thermal transfer method or a thermal method, and a method of manufacturing the same.

[0002]

2. Description of the Related Art A thermal print head is formed by forming a heat storage glaze layer made of glass or the like on a substrate by firing, and further forming an electrode pattern, a heating resistor, and a protective layer on the heat storage glaze layer. It is configured. Further, a driver IC, a connector, and the like for controlling the driving of the heating resistor through the electrode pattern are integrated with the substrate. The driver IC and the connector are electrically connected to each other through a terminal portion provided on a substrate separately from the printing portion, and a terminal pin of the connector is fixed to the terminal portion via an adhesive. .

As a substrate for such a thermal printhead, for example, an oxide-based alumina ceramics substrate made of a sintered body of aluminum oxide has been widely and generally used. The alumina ceramic substrate has a thermal conductivity of about 20 W / m · K. In the printing portion on such a substrate, heat generated from the heating resistor in accordance with the energized state of the electrode pattern is stored in the heat storage glaze layer and is released as printing heat through the protective layer with good thermal responsiveness. On the other hand, excess heat stored in the heat storage glaze layer is expected to be efficiently radiated from the bottom surface or the like through the substrate having the thermal conductivity.

[0004]

However, the alumina ceramic substrate having the above-mentioned thermal conductivity has a heat radiation effect that is not sufficient, and the energizing state of the electrode pattern is repeatedly turned on / off to continue the printing operation. In this case, the temperature difference between the top surface and the bottom surface of the substrate gradually increases as the amount of heat generated from the heating resistor increases, and the entire head warps and deforms due to thermal stress. If printing is performed in such a state in which the head is warped, there has been a problem that the contact state of the head with recording paper or the like becomes nonuniform, which adversely affects printing quality.

On the other hand, in the case of a substrate on which a sufficient heat radiation effect cannot be expected, the temperature of the upper surface in contact with the heat storage glaze layer does not drop sufficiently, and in the worst case, the terminal pins are fixed at the terminal portions on the substrate. The adhesive softens due to the heat,
There is a possibility that a contact failure between the terminal portion and the terminal pin may occur.

Accordingly, the present invention has been conceived in view of the above circumstances, and it is possible to improve the printing quality by using a substrate material having a high heat radiation effect and to solve other thermal problems. An object of the present invention is to provide a thermal print head and a method for manufacturing the same.

[0007]

DISCLOSURE OF THE INVENTION In order to solve the above problems, the present invention employs the following technical means.

That is, in the thermal print head provided by the first aspect of the present invention, a thermal storage glaze layer is formed on a substrate, and an electrode pattern, a heating resistor, and a protective layer are further formed on the thermal storage glaze layer. A thermal printhead formed and formed, wherein the substrate is a non-oxide ceramic substrate having excellent thermal conductivity. For example, a sintered body of aluminum nitride is used as the ceramic substrate.

According to the thermal print head provided by the first aspect in which the above technical measures are taken, the thermal conductivity of a non-oxide ceramic substrate made of a sintered body of aluminum nitride is a conventional one. It is sufficiently higher than an alumina ceramic substrate or the like, for example, 60 to 180
It has a thermal conductivity of about W / m · K. In other words, since the heat dissipation effect is sufficiently exhibited in the ceramic substrate of aluminum nitride, the temperature difference between the top surface and the bottom surface of the substrate is not so large as the amount of heat generated from the heating resistor increases during printing. In addition, the entire head does not significantly warp and deform due to thermal stress. Therefore, the printing operation can be continued without warping and deforming the head, so that the contact state of the head with recording paper or the like becomes uniform, and as a result, the printing quality can be improved.

In a preferred embodiment of the thermal print head according to the first aspect, the substrate includes:
A terminal portion for external connection may be provided, and a terminal pin may be fixed to the terminal portion via an adhesive.

According to such a structure, the aluminum nitride ceramic substrate sufficiently exerts the heat radiation effect as described above, so that the temperature of the upper surface of the substrate in contact with the heat storage glaze layer can be sufficiently reduced. The adhesive fixing the terminal pins in the upper terminal portion is not softened by the heat, so that a contact failure between the terminal portion and the terminal pins can be prevented.

A method of manufacturing a thermal print head according to a second aspect of the present invention includes forming a heat storage glaze layer on a substrate, further forming an electrode pattern and a heating resistor on the heat storage glaze layer, and A method for manufacturing a thermal print head formed by forming a protective layer, wherein a non-oxide ceramic substrate having excellent thermal conductivity is heat-treated at a predetermined high temperature as the substrate, and then further subjected to a heat treatment temperature. The method is characterized in that the heat storage glaze layer is fired at a low temperature. For example, a sintered body of aluminum nitride is used as the ceramic substrate.

According to the method of manufacturing a thermal print head provided by the second aspect in which the above technical means are employed, the same effect can be obtained by obtaining the thermal print head according to the first aspect. .
By the way, when manufacturing a thermal print head, for example, if the heat storage glaze layer is directly baked on a ceramic substrate made of a sintered body of aluminum nitride, a chemical reaction occurs due to the composition of the heat storage glaze layer and the substrate. Bubbles are generated, which causes a problem in the smoothness of the heat storage glaze layer. Therefore, it has been said that it is practically difficult to improve the printing quality even by employing a substrate made of a sintered body of aluminum nitride having excellent thermal conductivity. However, according to the manufacturing method according to the second aspect, the ceramic substrate made of the aluminum nitride sintered body is once subjected to a heat treatment at a high temperature, so that the above-described bubbles are generated during the firing of the heat storage glaze layer. Therefore, a smooth thermal storage glaze layer can be formed on the substrate, and a thermal print head having actually excellent print quality can be produced.

In a preferred embodiment of the method for manufacturing a thermal print head according to the second aspect, when the substrate is subjected to heat treatment, the substrate is subjected to heat treatment at such a high temperature that the surface of the substrate is deteriorated. Configuration.

According to this structure, an oxide layer having a certain thickness is formed on the surface of the substrate, and thereafter, the heat storage glaze layer is formed on the oxide layer by firing. At the time of firing, a chemical reaction between the oxide contained in the thermal storage glaze layer and the nitrogen contained in the substrate can be prevented by using the previously formed oxide layer as a barrier, and there is no bubble due to such a chemical reaction. A heat storage glaze layer can be formed on a substrate.

Other features and advantages of the present invention will become more apparent from the following description of embodiments of the present invention.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a plan view showing one embodiment of a thermal print head according to the present invention, and FIG. 2 is a plan view of FIG.
It is sectional drawing which showed the cross section which follows the II-II line. FIG.
In FIG. 7, fine patterns and details are simplified or shown for convenience.

As shown in these figures, the thermal print head A according to the present invention belongs to a so-called thick-film type, in which a heat storage glaze layer 11 is formed on a substrate 10 and further the heat storage glaze layer 11 is formed. Electrode pattern 12, individual electrode pattern 13 and heating resistor 1
4, and a protective layer 15 and the like are sequentially formed. A heat sink 20 made of aluminum or the like is fixed to the bottom surface 10 b of the substrate 10.
0, the heating resistor 1 through the electrode patterns 12 and 13
4 and a driver IC 30 for driving and controlling the
0 and the like are integrated.

The substrate 10 is a non-oxide ceramic substrate made of, for example, a sintered body of aluminum nitride and has a thermal conductivity of about 60 to 180 W / m · K.
The heat generated from the heating resistor 14 during the printing operation is transmitted to the substrate 10 via the heat storage glaze layer 11, and can be radiated from the bottom surface 10 b side of the substrate 10 via the radiator plate 20.

The heat storage glaze layer 11 is formed on the upper surface 1 of the substrate 10.
A glass paste is printed over the entire area 0a, and the glass paste is fired at a high temperature to form a film having a constant thickness. This heat storage glaze layer 11
Has the effect of discharging the printing heat to the outside with good thermal responsiveness through the protective layer 15 while storing the heat generated from the heating resistor 14. On the other hand, excess heat stored in the heat storage glaze layer 14 that does not contribute to printing is efficiently radiated from the bottom surface 10b side through the substrate 10 having the above-described thermal conductivity. The glass used as the raw material of the heat storage glaze layer 11 is assumed to be softened at a transition point of about 900 ° C., for example.

The common electrode patterns 12 and the individual electrode patterns 13 are arranged so as to alternately intersect in a comb-like shape at a fine equi-pitch interval at a position (printing portion P) where the heating resistors 14 are located. . When a current flows through the heating resistor 14 through the electrode patterns 12 and 13, a sharp temperature rise occurs due to heat generation in each minute portion of the heating resistor 14, thereby performing printing by a thermal transfer method or a heat-sensitive method. It is.

The heating resistor 14 is formed so as to straddle the common electrode pattern 12 and the individual electrode pattern 13 in the printing portion P along a straight line. This heating resistor 14
In some cases, the contact surface pressure against the ink ribbon, the thermal paper, or the like is good because the printing portion P has a cross-sectional shape that is swelled by that amount.

When the ink ribbon or the thermal paper slides while receiving heat from the heating resistor 14, the protective layer 15
It is formed to improve abrasion resistance and slidability. The protective layer 15 is not limited to one layer, and may be formed of two or more layers.

The heat radiating plate 20 has an effect of efficiently radiating the heat transmitted from the heat storage glaze layer 11 through the substrate 10.
This is effective in preventing deformation of the substrate 10 due to heat.

The driver IC 30 includes the individual electrode pattern 1
In addition to being connected to the terminal pattern 31 formed on the surface of the thermal storage glaze layer 11 apart from the electrode portions 12 and 13 by a wire bonding, the terminal pattern 31 is connected to the terminal pattern 31 formed separately from the printing portion P.
The terminal pattern 31 is formed between terminal portions T, which are connection portions of the connector 40 described later.

The connector 40 has terminal pins 41, and the terminal pins 41 are electrically connected to the terminal patterns 31 at the terminal portions T, T. Also, terminal pin 4
1 is securely connected to the terminal pattern 31 in a state where it is sealed with an adhesive 50 such as an ultraviolet curable resin, for example, in order to protect it from outside air while being connected to the terminal pattern 31. The adhesive 50 used in the present embodiment softens at, for example, about 70 ° C.

Next, a method of manufacturing the thermal print head having the above configuration will be described.

First, before the thermal storage glaze layer 11 is formed on the upper surface 10a of the substrate 10 made of a sintered body of aluminum nitride, for example, the substrate 10 is once subjected to 1000 to 1000 hours.
It is exposed to a heat treatment at about 1100 ° C. Then, substrate 1
A very thin oxide layer is produced over the zero surface compared to the whole. This oxide layer exhibits a barrier effect of preventing a chemical reaction at a high temperature between nitrogen of aluminum nitride contained in the composition of the substrate 10 and oxide contained in the heat storage glaze layer 11.

FIG. 3 is a diagram showing the relationship between the thickness of an oxide layer formed by subjecting a sintered body of aluminum nitride to heat treatment and the temperature. Note that a sintered body of aluminum nitride having a thickness of about 10 mm was used. As shown in FIG.
Heat treatment at a lower temperature for about 1 hour,
An oxide layer (Al ₂ O ₃ ) that does not reach 0.5 μm is generated. In this case, nitrogen and oxide react with each other in a formation process of the heat storage glaze layer 11 to be described later, so that NO _X bubbles are generated. Therefore, in the present embodiment, 1000 to 1100 is set so that an oxide layer having a sufficient thickness is generated.
Heat treatment at about ° C. Although heat treatment may be performed at a higher temperature, the thermal conductivity of the entire substrate 10 is reduced by the oxide layer itself.

After heat-treating the substrate 10 at the high temperature as described above, a glass paste is applied on the entire upper surface 10a of the substrate 10 by printing, and the temperature is lower than the heat treatment temperature at the time of forming the oxide layer. Is fired at a temperature lower than the transition point of, for example, about 810 ° C. Thereafter, the substrate 10 is cooled to room temperature, so that the heat storage glaze layer 11 having a certain thickness and being solidified is formed on the upper surface 10a.
Is formed. At this time, since an oxide layer has already been generated on the upper surface 10a of the substrate 10, it is unlikely that the substrate 10 and the thermal storage glaze layer 11 cause a chemical reaction due to high temperature to generate bubbles as described above. Therefore, the heat storage glaze layer 11 is formed uniformly and smoothly. The temperature at which the heat storage glaze layer 11 is baked depends on the temperature of the substrate 10.
Is reduced to a temperature lower than the temperature at which an oxide layer is formed by heat treatment, so that the thickness of the already formed oxide layer does not further increase, and the thermal conductivity of the entire substrate 10 does not decrease. Absent.

Next, electrode patterns 12 and 13 and terminal patterns 31 having a predetermined shape are formed on the heat storage glaze layer 11 by a photolithography method or the like in the same manner as in the prior art. Forming a resistor 14;
Further, the protective layer 15 is formed by a sputtering method or the like as in the conventional case. Finally, the driver IC 30 connected to the individual electrode pattern 13 and the terminal pattern 31 by wire bonding is sealed with the resin 60, and the terminal pins 41 of the connector 40 are bonded and fixed to the terminal pattern 31 with the adhesive 50. Thus, the thermal print head A is completed.

In the thermal print head A obtained as described above, the temperature measured at each part by causing the heating resistor 14 to generate heat is shown in the following table. In addition, as a comparative example, a measurement result in the case where the configuration such as the shape and dimensions is the same as that of the thermal print head A of the present embodiment and the only difference is that the material of the substrate is aluminum oxide (Al ₂ O ₃ ) is shown. . In both the present embodiment and the comparative example, the temperature of the heating resistor was adjusted to 150 ° C. using a thermal print head having a dimensional distance from the printing unit to the terminal unit of about 7 mm, and the temperature of each unit was measured. Was.

[0034]

[Table 1]

As shown in the table, in the aluminum nitride (AlN) substrate 10 according to the present embodiment, the printing portion P
When the surface temperature is 163 ° C., the surface temperature of the terminals T and T does not reach 70 ° C. even when the elapsed time from the start of heat generation is 2 minutes after the adhesive 50 starts to soften. Therefore, the contact state between the terminal pin 41 of the connector 40 and the terminal pattern 31 is reliably maintained via the adhesive 50. On the other hand, the aluminum oxide (A
l ₂ O ₃ ) made of alumina ceramic substrate
One minute after the start of heat generation, the temperature exceeds the temperature at which the adhesive 50 softens, and a contact failure between the terminal pin 41 and the terminal pattern 31 occurs.

Also, a substrate made of aluminum nitride (AlN)
In No. 10, aluminum oxide (Al _TwoO_Three) Compared to the substrate
Because the surface temperature does not rise suddenly,
The heat is efficiently radiated from the surface 10b through the heat radiating plate 20.
It is thought that it is. That is, the substrate 10 of the present embodiment
Temperature difference between the top surface 10a and the bottom surface 10b in the conventional example
It is smaller than the alumina ceramic substrate,
By continuing the printing operation, the emission from the heating resistor 14
Due to the increase in the amount of heat, the thermal stress
A state in which the whole is warped is effectively prevented.

Therefore, according to the thermal print head A formed through the above-described manufacturing process, the substrate 10 made of aluminum nitride ceramics sufficiently exerts a heat radiation effect. As the amount increases, the printing operation can be continued without the entire head being greatly warped and deformed,
By making the contact state of the head with recording paper or the like uniform, the printing quality can be improved as compared with the related art.

Since the aluminum nitride ceramic substrate 10 can be expected to have a sufficient heat radiation effect in combination with the heat radiating plate 20, it is possible to sufficiently lower the temperature of the upper surface 10a of the substrate 10 in contact with the heat storage glaze layer 11. The adhesive 50 fixing the terminal pins 41 of the connector 40 at the terminal portions T, T on the substrate 10 is not softened by heat, and the contact failure between the terminal pattern 31 and the terminal pins 41 is prevented. it can.

Further, when the thermal print head A is manufactured, the ceramic substrate 1 made of aluminum nitride is used.
By heat-treating 0 to form an oxide layer on the surface of the substrate 10, even when the heat storage glaze layer 11 is formed thereafter, a chemical reaction does not occur between the glass and the substrate 10 so that bubbles are not generated. Therefore, a smooth thermal storage glaze layer 11 can be formed on the substrate 10, and a thermal print head A having actually excellent print quality can be produced.

The present invention is not limited to the above embodiment.

For example, the present invention can be applied not only to a thick film type thermal print head but also to a thin film type. Further, as the material of the substrate 10, a material having excellent thermal conductivity other than aluminum nitride may be employed.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of a thermal print head according to the present invention.

FIG. 2 is a sectional view showing a section taken along line II-II of FIG.

FIG. 3 is a diagram showing the relationship between the thickness of an oxide layer formed by performing a heat treatment on a sintered body of aluminum nitride and the temperature.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Substrate (aluminum nitride ceramic substrate) 11 Thermal storage glaze layer 12, 13 Electrode pattern 14 Heating resistor 15 Protective layer 41 Terminal pin 50 Adhesive A Thermal print head T Terminal part

Claims (6)

[Claims] 1. A thermal print head comprising: a heat storage glaze layer formed on a substrate; and an electrode pattern, a heating resistor, and a protective layer formed on the heat storage glaze layer. A thermal printhead, characterized by being a non-oxide ceramic substrate having excellent thermal conductivity. 2. The thermal printhead according to claim 1, wherein a sintered body of aluminum nitride is used as the ceramic substrate. 3. The thermal circuit according to claim 1, wherein a terminal portion for external connection is provided on the substrate, and a terminal pin is fixed to the terminal portion via an adhesive. Print head. 4. A method for manufacturing a thermal print head, comprising forming a heat storage glaze layer on a substrate, and further forming an electrode pattern, a heating resistor, and a protective layer on the heat storage glaze layer, A thermal print head, wherein a non-oxide ceramic substrate having excellent thermal conductivity is heat-treated at a predetermined high temperature as the substrate, and then the heat storage glaze layer is fired at a temperature lower than the heat treatment temperature. Manufacturing method. 5. The method according to claim 4, wherein a sintered body of aluminum nitride is used as the ceramic substrate. 6. The method for manufacturing a thermal print head according to claim 4, wherein, when the substrate is subjected to the heat treatment, the substrate is subjected to the heat treatment at such a high temperature that the surface of the substrate is deteriorated. .