JPH0626911B2 - Thermal print head - Google Patents

Description

The present invention relates to a thermal print head used in a thermal type or thermal transfer type printer.

<Prior Art> In general, as a thermal print head of this type, there is one as shown in a plan view of FIG. 4, for example. In the figure,
Reference numeral 1 is an insulating substrate, and a glaze layer 2 (see FIG. 5) is formed on one surface of the insulating substrate 1, and a heating resistor 3 is formed via the glaze layer 2. The heating resistor 3 is composed of a strip-shaped continuous resistor,
Each of the printing dot units is individually connected to the drive circuit 4 and the common electrode 5. The drive circuit 4 controls energization of the heating resistor 3 for each print dot unit based on a control signal, and is mounted on the insulating substrate 1. The drive circuit 4 and the common electrode 5
And the heating resistor 3 are connected by a plurality of lead electrodes 6a and 6b formed on the insulating substrate 1, respectively.

As shown in FIG. 5, the thermal printing head having such a structure usually prints and fires the glaze layer 2 on one surface of the insulating substrate 1 with a predetermined thickness, and then the glaze layer 2 and the insulating substrate 2 are heated. The lead electrodes 6a and 6b are printed and fired by a screen printing method over the upper surface of the substrate 1, and the heating resistor 3 is printed and fired so as to cross the ends of the lead electrodes 6a and 6b.

<Problems to be Solved by the Invention> By the way, conventionally, the lead electrodes 6a and 6b are made of gold (A
It is composed of a conductive material containing u) as a main component, for example, a gold paste obtained by mixing a resin with gold, but in this case, printing and firing only once by the screen printing method described above,
Due to the material characteristics of the gold paste, the sintering of gold is first carried out and agglomerated in the paste, and as a result, as shown in FIG. 7, a portion where gold is present at a high density in the formed electrode layer. A (7th
(Indicated by hatched portions in the figure) and a portion where the gold is sparse, that is, a so-called transparent portion B, is formed, and the gold film is not densely formed. Therefore, conventionally, when the lead electrodes 6a and 6b are formed, they are printed and fired once, and then are printed and fired once or twice more, and finally the skein portion B is eliminated. , The conductor resistance was adjusted.

However, the lead electrodes 6a and 6 thus formed are
Since b has a considerably large thickness of 2 μm to 6 μm, it has the following problems.

First, in such a thermal print head, it is usually necessary to raise the surface temperature of the heating resistor 3 to about 300 ° C. to 500 ° C. at the time of driving, but with the thick lead electrodes 6a, 6b, As a result, the heat dissipation effect is also increased. Therefore, in the past, in order to prevent the heat radiation effect of the lead electrodes 6a and 6b from affecting the driving of the heating resistor 3, it was necessary to increase the thickness of the glaze layer 2.

Further, when the lead electrodes 6a and 6b have a large thickness in this manner, as shown in FIG. 5, irregularities due to the thickness of the lead electrodes 6a and 6b occur on the surface of the heating resistor 3. Therefore, as shown in FIG. 6, when the heating resistor 3 is printed, bleeding b occurs in a portion sandwiched between the lead electrodes 6a and 6b, resulting in a problem in print quality. Also becomes.

Furthermore, as the thickness of the lead electrodes 6a and 6b increases,
Since the amount of gold paste used increases, there is a problem that the manufacturing cost is high.

The present invention has been made to eliminate such conventional problems, and suppresses the heat dissipation effect of the lead electrodes,
It is intended to improve the printing quality and reduce the manufacturing cost.

<Means for Solving Problems> In order to achieve such an object, the present invention is characterized in that a conductor such as a lead electrode is made of a material obtained by kneading a gold paste and an organic gold paste. It is a thing.

<Examples> Hereinafter, the present invention will be described in detail based on Examples shown in the drawings. The thermal print head of this embodiment has substantially the same structure as the thermal print head of the conventional example shown in FIG. 4, and the same parts as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted. Omit it.

FIG. 1 is an enlarged plan view of an essential part of this embodiment, FIG. 2 is a sectional view taken along the section line II-II in FIG.
The drawing is a sectional view taken along the section line III-III in FIG. In these drawings, a lead electrode 60a wired between a drive circuit (not shown) and the heating resistor 3 and a lead electrode 6 wired between the common electrode 5 and the heating resistor 3
0b is arranged so as to face each other with the heating resistor 3 interposed therebetween, and the heating resistor 3 of both the lead electrodes 60a and 60b.
The connecting portions with and are arranged in a comb shape in a state of alternately intersecting.

Each of the lead electrodes 60a and 60b is made of a material obtained by kneading a gold paste and an organic gold paste.

This gold paste is a publicly known one made by mixing resin into particulate gold. Further, the organic gold paste is composed of an organic compound of gold and a resin, and for example, there is one sold by Engelhard Co., Ltd. in the United States under the product name of “Metal Organics”.

The organic gold paste and the normal gold paste are kneaded in the paste state in a ratio of 1: 1. As a device used for kneading these conductive materials, a known device such as a roller-type kneading machine or a rock mass machine is used.

The conductive paste material obtained by kneading the gold paste and the organic gold paste has a small shrinkage amount of gold in the material during firing and is evenly distributed over the entire printing layer.
A dense electrode layer is formed. In addition, the lead electrode 60a,
60b is set to a thickness of about 0.5 μm to 1 μm, but even such a thin film does not cause a scaly portion in the electrode layer. Therefore, a dense electrode layer having a specified thickness can be formed by printing and firing only once.

The lead electrodes 60a and 60b may be composed of only the organic gold paste, but in this case, the organic gold paste is 0.2 μm or more when printed and fired only once.
Since only an electrode layer having a thickness of about 0.3 μm can be obtained, the conductor resistance becomes too large. For this reason, if the lead electrodes 60a and 60b are formed using the organic gold paste alone,
Printing and firing must be repeated about once, and the production process becomes complicated accordingly.

Since each of the lead electrodes 60a and 60b has a thickness of only half or less as compared with the conventional example, the heat radiation effect on the heating resistor 3 is suppressed. Therefore, when forming the glaze layer 2 that functions as a heat storage layer, its thickness can be reduced.

Further, since the heating resistor 3 is formed on the lead electrodes 60a, 60b, as shown in FIG. 3, the surface of the heating resistor 3 on the lead electrodes 60a, 60b is the other part. While swelling from the surface of the sheet, some bleeding occurs at the time of printing. In this respect as well, since the thickness of the lead electrodes 60a and 60b is small, there is no unevenness enough to affect the print quality. . Further, the amount of gold used also decreases as the thickness decreases.

In addition, according to each of the above-mentioned examples, it has been proved that the manufacturing cost can be reduced by about 50% by reducing the gold content. Further, it is possible to suppress the variation in the resistance value of the lead electrodes 60a and 60b to ± 15%.

<Effects of the Invention> As described above, according to the present invention, after the conductor for energization connected to the heating resistor is made of the material obtained by kneading the gold paste and the organic gold paste, the conductor is made to have a thickness of about 1 μm. It can be formed with a small thickness. Therefore, the heat radiation effect of this conductor can be suppressed, and for example, in the case of the one having the glaze layer, the thickness of these can be reduced. Further, the pattern of the heating resistor after printing becomes clear, variation in resistance value is suppressed, and printing quality is improved. Furthermore, since a thickness of about 1 μm can be obtained by printing and firing once, the number of printings can be reduced and the amount of expensive gold used can be reduced, which can significantly reduce the manufacturing cost. become.

[Brief description of drawings]

1 to 3 show an embodiment of the present invention, FIG. 1 is an enlarged plan view of an essential part of this embodiment, FIG. 2 is a sectional view taken along the section line II-II in FIG. FIG. 4 is a sectional view taken along the section line III-III in FIG. 2, FIG. 4 is a plan view of a general thermal printing head, FIG. 5 is a longitudinal sectional view of a main part of a conventional example, and FIG. 6 is FIG. FIG. 7 is a cross-sectional view taken along the line VI-VI in FIG. 7, and FIG. 7 is a partially taken out plan view showing an inconvenient formation state of the lead electrode. 1 ... Insulating substrate, 2 ... Glaze layer, 3 ... Heating resistor, 60a, 60b ... Lead electrode (conductor),

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location H05K 1/16 6921-4E

Claims (1)

[Claims] 1. A thermal printing head comprising a heating resistor and a conducting conductor connected to the heating resistor, wherein the conductor is made of a material obtained by kneading a gold paste and an organic gold paste. Characteristic thermal print head.