JPH04319447A - Thermal head manufacturing method - 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]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer head used in computers, word processors, facsimile machines, etc.

0002

[Prior Art] Among printing devices, thermal printers are
It has the characteristics of low price, low noise, and is maintenance free, and is widely used, especially for personal use.

However, thermal printers have a problem in that it is difficult to print at high speed on paper with a large surface roughness (rough paper).

In order to solve this problem, conventionally, as shown in FIG. 6, the glass glaze 2 formed on the substrate 1 is
Efforts have been made to improve adhesion to rough paper and obtain good printing by narrowing the width and increasing the thickness of the glass glaze. Generally, in order to narrow the width and increase the thickness of a glass glaze, it is necessary to lower the fluidity of the glass glaze melted during firing of the glass glaze. However, by suppressing the fluidity of the glass glaze during melting, there was a problem in that the surface of the glass glaze did not become smooth and remained as undulations. For this reason, at present, the glass glaze has a width of about 550 microns and a thickness of about 50 microns.

Furthermore, as disclosed in Japanese Patent Publication No. 2-46390, an upper glass glaze layer is further printed and fired on top of the partially formed glass glaze, thereby improving the adhesion of the heat generating part to the paper. A thermal head that prints sharply and clearly has been proposed. However, in a thermal head configured in this way, it is necessary to lower the firing temperature of the upper glass glaze layer than that of the lower glass glaze layer. Thermal heads that print at higher speeds have a lower heat-resistant temperature.
There were problems such as poor thermal durability.

[0006]

The problem to be solved is that it is currently difficult to perform high-speed, high-quality printing on paper with a large surface roughness.

[0007]

[Means for Solving the Problems] The present invention aims to print at higher speed on paper with a large surface roughness by partially removing glass glaze and then baking it. Achieved with large curvature without compromising heat resistance.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a method of manufacturing a thermal head according to an embodiment of the present invention.

A glass frit is printed on a substrate 1 by a general screen printing method and fired to form a glass glaze layer 2 (FIG. 1(a)). Next, a photosensitive resin 4 is coated, and the photosensitive resin 4 is removed from the portion where the glass glaze layer 2 is to be removed. Generally, a hydrofluoric acid-based etching solution is used to partially remove the glass glaze layer 2, but the photosensitive resin 4 may peel off during the etching process. In such a case, the metal layer 3 is formed on the glass glaze layer 2, and the photosensitive resin 4 is further coated, and then the photosensitive resin 4 and the metal layer 3 in the removed portion of the glass layer 2 are removed (see FIG. 1). (b)). Next, the glass glaze layer 2 is removed using a hydrofluoric acid-based etching solution (FIG. 1(c)).
. Furthermore, by removing the photosensitive resin 4 and the metal layer 3, a partially protruding glass glaze layer 2 can be obtained. (FIG. 1(d)) The glass glaze thus obtained has a problem in that the interface (etched edge) 5 between the removed portion and the non-removed portion of the glass glaze becomes sharp, as shown in FIG. There is a point. Next, the etched end 5
I will explain the problem of sharp edges.

FIG. 3 is a diagram showing the manufacturing process of the thermal head. A heating resistor layer 10 is formed by sputtering or the like on the substrate 1 on which the glass glaze 2 described in FIG. 1 is formed. Next, the electrode layer 11 is formed in the same manner (FIG. 3(a)
)). At this time, if the etched edge 5 is sharp, the film cannot be formed uniformly on the wall surface 6 of the step between the etched part and the non-etched part, and the thickness of the heat generating resistor layer 10 becomes thin in some parts. This causes poor thermal durability during heat generation. Further, a photosensitive resin 4 is coated on the electrode layer 11, and the electrode layer 11 is divided into a lead electrode 11-1 and a common electrode 11-2 to form a heat generating part 12 (FIG. 3(b)).
). At this time, since the etched edge 5 is sharp, there is a problem that the thickness of the photosensitive resin 4 is not uniform and the pattern accuracy of the heat generating part 12 is deteriorated (FIG. 3(c)).

The present invention solves these problems by partially removing the glass glaze and then firing it at a temperature equal to or higher than the yield point of the glass glaze.

FIG. 4 is a diagram showing changes in the shape and surface condition of a glass glaze when the firing temperature and firing conditions are changed. FIG. 4(a) shows a state in which the etched edge 5 is not sufficiently blunted due to insufficient firing temperature and time, and FIG. 4(b) shows a state in which the etched edge 5 is not sufficiently blunted due to excessive firing temperature and time. This is the case when a certain curvature cannot be obtained. FIG. 4C shows an ideal state in which the etched edges are sufficiently blunted and the unetched portions have a large curvature remaining. Table 1 summarizes the shapes and surface conditions when the firing temperature and firing time are varied. Regarding the shape, the state in FIG. 4(a) is marked as x, the state in FIG. 4(b) as Δ, and the state in FIG. 4(c) as ○. Also,
The surface condition shows that as it goes from x to △ to ○, the surface becomes smoother than glass. However, the yield point of the glass glaze used in this table is 850°C.

[0013]

[Table 1]

As can be seen from Table 1, as the firing temperature increases, the shape changes from FIGS. 4(a) to 4(b) to 4(c).
). However, as the firing time increases, the surface condition of the glass glaze deteriorates. When fired at a temperature that exceeds the yield point of the glass glaze, a nearly good shape and surface condition can be obtained.For the products tested this time, firing at 920℃ for about 10 to 15 minutes resulted in a good shape and surface condition. It was the best.

The firing temperature and firing time described in this embodiment vary depending on the type of glass glaze and the amount of printing, and are not limited to these.

[0016] The method for removing glass glaze has been described above.
Although removal by etching has been described, removal by grinding is also possible. FIG. 5 describes an example of grinding using a dicing saw.

Forming glass glaze 2 on substrate 1 (
Figure 5(a)). Using the cutting blade 20, the INDEX 21 in the Z direction is set to approximately the thickness of the substrate, and the glass glaze 2 is ground. (FIG. 5(b)) Furthermore, grinding is performed again so that only the glass glaze forming the heat generating portion remains (FIG. 5(c)). By firing the substrate obtained in this way under the above temperature conditions, it is possible to obtain a substrate for a thermal head with a smooth surface and a large curvature of the heat generating part, similar to the substrate removed by etching.

[0018]

Effects of the Invention As explained above, in the thermal head of the present invention, by firing after removing a part of the glass glaze, the curvature of the heating element can be partially increased, so that It has the advantage of having high contact properties and being able to print at higher speeds.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a method for manufacturing a thermal head according to the present invention.

FIG. 2 is a diagram showing the state after etching according to the present invention.

FIG. 3 is a diagram illustrating a problem when the etched edge becomes sharp.

FIG. 4 is a diagram illustrating the shape of glass glaze when the firing temperature is changed.

FIG. 5 is a diagram showing a case where glass glaze is removed by grinding.

FIG. 6 is a diagram showing the shape of a glass glaze in a general thermal head.

[Explanation of symbols]

1 Substrate 2 Glass glaze 3 Metal layer 4 Photosensitive resin 5 Etched end 6 Stepped wall 10 Heat generating resistance layer 11 Electrode layer 11-1 Lead electrode 11-2 Common electrode 12 Heat generating part 20 Cutting blade 21
INDEX in Z direction

Claims (1)

[Claims] 1. A method for manufacturing a thermal head having a substrate, a glass glaze formed on the substrate, and a heat generating part formed on the glass glaze, including the step of removing a part of the glass glaze. 1. A method for manufacturing a thermal head, comprising the steps of: firing the substrate from which a portion of the glass glaze has been removed at a temperature at least equal to or higher than the yield point of the glass glaze.