JPH06255155A - Thermal head and its manufacture - Google Patents

Abstract

PURPOSE:To provide a thermal head wherein dispersion in resistance values of all resistors is little and its manufacture. CONSTITUTION:A gold pattern of an IC side individual electrode 72, a common electrode side individual electrode 74, and a common electrode body 76 is formed on a substrate. A band like resistor 80 is formed above the IC individual electrode 74 and the common electrode side individual electrode 74. Overglazes 92, 94 are formed on the band like resistor 80 and the individual electrode 74 and on the common electrode body part 76 excepting a gap part containing edge parts 742, 746. A pulse is applied to between the common electrode side individual electrode 74 and the adjacent IC side individual electrode 72 to carry out trimming each half bit. Thereafter, a connection part 100 which connects the common electrode side individual electrode 74 to the common electrode body part 76 is printed and burnt at 200 deg.C or lower in burning temperature to form a gap part 95. A seal part 110 is formed on an upper surface of the connection part 100 by printing and burning that at 200 deg.C or lower in burning temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head in which a plurality of heating resistors are arranged in parallel in the main scanning direction, and more particularly to a thermal head applicable to a printer or the like aiming at high quality recording.

[0002]

2. Description of the Related Art Conventionally, a thick film type thermal head has electrodes 3 and 4 which are alternately drawn on a substrate, and a heating resistor 6 which is arranged in the main scanning direction so as to connect the electrodes 3 and 4. And an overglaze layer 2 covering the surface (see FIG. 12). One end of the electrode 4 is connected to the common electrode 5, and when the common electrode 5 and, for example, the individual electrode 3c are energized, the B portion of the heating resistor 6 generates heat and contacts the B portion of the heating resistor 6. The color of the thermal paper. Since the recording density of the thermal paper at this time depends on the heat generation amount per bit of the heating resistor of the thermal head, if the resistance value varies among the heating bits, the heat generation amount for each bit is different. This caused uneven printing density.

Therefore, when a thermal head having a high image quality is manufactured, a resistance value is corrected by applying a high charge pulse to the heating resistor 6. For example, when a pulse is applied between the common electrode 5 and the electrode 3c to correct the resistance value, the electrode 4
c between the electrode 3c and the heating element b, the electrode 3c and the electrode 4d
The resistance value of the heating element portion b ′ between and is simultaneously corrected. As described above, when the resistance value is corrected bit by bit, the resistance values can be accurately matched as the combined resistance of the heating element parts b and b ′. The resistance values of 'are not the same. Therefore, in the resistance value measurement for each bit, even if the resistance variation is within 1% due to the maximum variation, the resistance values of the resistor parts b and b ′ in the same bit are actually the same because of the variation. This also resulted in uneven print density within the bit.

Therefore, a trimming (correction of resistance value) method for eliminating variation in resistance value in the same bit (Japanese Patent Laid-Open No. 63-
(See Japanese Patent Publication No. 59555, Japanese Patent Laid-Open No. 2-72969)
In order to perform the above, the electrodes on the common electrode 40 side of the electrodes 30 and 40 alternately drawn as shown in FIG.
a, 40b, 40c ... 40f) are formed separately. In the trimming in this case, for example, a pulse can be separately applied between the electrode 40c and the electrode 30c and between the electrode 40d and the electrode 30c, so that the resistance values of the heating elements b and b'are independently adjusted. You can Then, after the correction of all the bits is completed, each electrode on the side of the common electrode 40 is printed and fired with an electrically conductive material such as a current-carrying paste to be connected and connected.

[0005]

However, when the connecting material is printed and fired on the common electrode side after the trimming process to form the connecting portion, the resistance value variation suppressed by the trimming in the firing process is widened again. There has occurred. The applicant experimented with the variation of the resistance value variation of the heating resistor with respect to the annealing temperature in the thermal head after the pulse trimming process. The change rate of the variation in resistance value was expressed by obtaining the difference between the variation width after annealing and the variation width after trimming. Then, the firing time is set to 30 minutes,
The experimental temperature was measured from 100 ° C to 700 ° C at every 100 ° C. The results are shown in the graph of FIG. In this graph, the horizontal axis represents the annealing temperature, and the vertical axis represents the rate of change in resistance value variation (resistance value variation = resistance value variation after annealing (SIGMA) -resistance value variation after trimming (SI
GMA)) is shown. From this result,
It can be seen that the higher the annealing temperature, the higher the rate of change of the resistance value, and the wider the variation of the resistance value after annealing. And
It was also found that when the anneal temperature was set to 200 ° C. or less, the variation in the resistance value after trimming and after anneal hardly changed.

From the results of this experiment, according to the present invention, the operating temperature after trimming at the time of making the thermal head is 200.degree.
By the following, it is possible to provide a belt-shaped thermal head with extremely small variation in resistance value by preventing the variation in resistance value that is aligned by the half (half) bit trimming.

[0007]

SUMMARY OF THE INVENTION A thermal head according to the present invention comprises a strip-shaped common electrode body extending on the insulating substrate in the main scanning direction and a common electrode body extending in the multiple scanning direction on the insulating substrate. An individual electrode having a plurality of individual electrodes that can be connected to the IC side that are separated and extended, and a plurality of individual electrodes that can be connected to the common electrode body, and a strip-shaped main electrode above or below the plurality of individual electrodes A heating resistor formed in the scanning direction, an overglaze covering the upper surfaces of the individual electrodes, the heating resistor and the common electrode body except for the gap, and the common electrode body and the common electrode body A connection part made of a conductor disposed between an individual electrode that can be connected to the sheet and a shield formed on the connection part.
And a connecting part and a seal part have a firing temperature of 20.
It has a structure made of a material that can be fired at 0 ° C. or lower.

In the method for manufacturing a thermal head according to the present invention, a strip-shaped common electrode body portion extending in the main scanning direction and a large number of individual electrodes extending from the body portion in the sub-scanning direction are formed on the substrate. And a step of connecting the individual electrodes to form a strip-shaped heating resistor extending along the main scanning direction,
Forming a gap along one end of the individual electrode and one end of the common electrode body to form an overglaze on the upper surface of the individual electrode, the heating resistor, and the common electrode body; Connection for connecting the common electrode body and the individual electrode connected to the common electrode body with the process of applying a pulse between the electrode and the adjacent individual electrode to correct the resistance value of the heating resistor for each half bit And a step of forming the seal portion on the upper surface of the connection portion by baking after printing at a baking temperature of 200 ° C. or less.

[0009]

The connecting portion for connecting the individual electrode constituting the thermal head and the common electrode body is formed along the gap of the overglaze, so that the individual electrode and the common electrode are surely integrated. Can be converted. Further, since the connecting portion and the seal portion formed on the upper surface of the connecting portion are made of a material capable of being fired at a firing temperature of 200 ° C. or less, the resistance value of the heating resistor can be corrected (trimmed) after the work. The firing temperature can be lowered. Then, by extremely reducing the resistance value variation due to firing after trimming the heating resistor, it is possible to manufacture a belt-shaped thermal head corresponding to high image quality in which the resistance values of the two heating portions in the same bit of the belt-shaped resistor have less variation. .

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic view of a thermal head according to the present invention, FIG. 2 is a sectional view taken along line AA of FIG. 1, and FIGS.
Reference numeral 0 is an explanatory view of the manufacturing process of the thermal head. First, the structure of the thermal head will be described in the order of steps. First Step A gold pattern is formed on a substrate (see FIGS. 3 and 4). A MOD gold film is formed so as to cover the partial glaze 62 of the ceramic substrate 60, and a strip-shaped common electrode main body portion 76 extending along the direction X which is the main scanning direction is separated by photolithography etching. A large number of common electrode side individual electrodes 7 extending in the sub scanning direction Y.
4 and the tips of the common electrode side individual electrodes 76 and the tips thereof are arranged in a staggered manner to form a gold pattern of a large number of IC side individual electrodes 72 extending to the IC side.

Second step A band-shaped resistor is formed on the gold pattern of the substrate (see FIGS. 5 and 6). A negative resist is spin-coated on the gold pattern, and an opening is formed by photolithographic etching at a position where a resistor is to be formed, that is, a portion where the common electrode side individual electrode 74 and the IC side individual electrode 72 are alternately overlapped. . Next, a resistor paste is embedded in the opening by printing, dried, lapped to flatten the surface and baked. In this baking, the resist is burned off, and a strip-shaped resistor extending in the main scanning direction is formed so that the electrode 74 and the electrode 72 are continuous at the portion where the common electrode side individual electrode 74 and the IC side individual electrode 72 are alternately overlapped. A body 80 is formed.

Third step: An overglaze layer is formed (see FIGS. 7 and 8). The overglaze 90 has an individual electrode side overglaze 92 and a common electrode main body side overglaze 94 with a gap 95 therebetween, and is formed by printing and firing. Individual electrode side over glaze 92
Is formed on the entire surface of the common electrode side individual electrode 74 except for the individual electrode end portion 742 of the common electrode main body portion 76 side, which covers the IC side individual electrode 72 and the resistor 80. The common electrode body side overglaze 94 is an IC on the common electrode body portion 76.
The part other than the common electrode end 762 on the side individual electrode 72 side, from the individual electrode side overglaze 92 to the gap 9
The common electrode body 76 is formed on the upper surface of the common electrode body 76 with a distance of 5. The gap 95 is between the individual electrode side overglaze 92 and the common electrode body side overglaze 94.
It is a portion where there are no scratches and has an individual electrode end portion 742 and a common electrode end portion 762.

Fourth Step Pulse trimming is performed (see FIGS. 7 and 8). Trimming is performed on the common electrode side individual electrode 74
Then, a pulse is applied between the adjacent IC-side individual electrodes 72 for every half bit. At this time, the individual electrode end portion 742 in the gap portion 95 on the common electrode side individual electrode 74 side contacts the probe of the prober as an electrode pad. For example, a voltage is applied between the common electrode side individual electrode 74a and the IC side individual electrode 72a to trim the resistor b portion, and then a voltage is applied between the common electrode side individual electrode 74b and the IC side individual electrode 72a. The resistor b'part is trimmed.

Fifth step A connecting portion between the common electrode side individual electrode and the common electrode main body portion is formed in the gap of the overglaze (see FIGS. 9 and 10). The connection part 100 is printed with an epoxymelamine-based silver epoxy resin in the gap 95 formed on the individual electrode end 742 and the common electrode end 762 without overglazing, and baked. To form. Firing at this time was performed at a firing temperature of 180 ° C. for 30 minutes. The individual electrode end portion 742 and the common electrode end portion 762 are connected via the connection portion 100, and the common electrode side individual electrode 7
4 and the common electrode body 76 are integrated.

Sixth step The connecting portion is sealed to form a thermal head (see FIGS. 1 and 2). Seal part 11
0 is formed on the connection part 100 by printing and baking a phenol resin. The firing temperature is 180 ° C and the firing time is 3
It was set to 0 minutes. In the thermal head configured as described above, the connection portion 100 and the seal portion 110 are formed by using a material capable of achieving firing at a firing temperature of 180 ° C., an epoxy melamine-based silver epoxy resin and a phenol resin. Therefore, in the firing work in the fifth step and the sixth step after trimming the resistance value, it is possible to work at a firing temperature of 200 ° C. or less, and the resistance value of the heating resistor of the thermal head after firing is trimmed. Can be maintained at the resistance value of.

In the method of manufacturing the thermal head of this embodiment, the individual electrodes 7 are surely filled by filling the gaps 95 of the overglades 92 and 94 with a conductive material and firing it.
4 and the common electrode body 76 can be integrated so as to be able to conduct electricity. Furthermore, since the thermal head after the resistance value of the heating resistor is corrected is not processed at high temperature, the variation in the resistance value after trimming hardly increases, and the manufactured thermal head has an extremely large variation in the resistance value. We were able to realize a thermal head that is compatible with low image quality.

[0017]

Advantageous Effects of Invention A server having a strip-shaped heating resistor of the present invention
Since the Mullhead can correct the resistance value of the heating resistor for each half bit, there is no variation in the resistance value of the two heating portions in the same bit of the heating resistor. Moreover, since the connecting portion and the seal portion are made of a material that can be fired at a low temperature (200 ° C. or less), there is no change in the resistance value of the heating resistor during the construction of the thermal head, and the correction is performed by pulse trimming. It is a thermal head that can maintain high resistance and satisfy high gradation, and can be used for high image quality.

According to the method of manufacturing a thermal head of the present invention, after the variation of the resistance value of the entire heating element and the variation of the resistance value in the same bit are corrected in the step of correcting the resistance value of each half bit of the heating resistor,
Since high temperature processing is not performed in the connection part formation process and the seal part formation process, the resistance value of the entire resistor and the resistance value in the same bit corrected in the correction process of the resistance value for each half bit can be maintained, and the variation in resistance value can be expanded. A manufacturing method that does not cause
It is possible to obtain a thermal head having no variation in resistance value. Further, in forming the common electrode, the individual electrode and the common electrode main body can be surely integrated so as to be able to conduct electricity only by firing the conductive material in the gap of the overglaze.

[Brief description of drawings]

FIG. 1 is a top view of a thermal head according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an explanatory diagram of a first step.

4 is a sectional view taken along line AA of FIG.

FIG. 5 is an explanatory diagram of a second step.

6 is a sectional view taken along line AA of FIG.

FIG. 7 is an explanatory diagram of a third step and a fourth step.

8 is a cross-sectional view taken along the line AA of FIG.

FIG. 9 is an explanatory diagram of a fifth step.

10 is a cross-sectional view taken along the line AA of FIG.

FIG. 11 is a graph showing the rate of change in resistance value variation with annealing temperature.

FIG. 12 is an explanatory view of a conventional thermal head.

FIG. 13 is an explanatory view of a conventional thermal head.

[Explanation of symbols]

60 ceramic substrate, 72 IC side individual electrode, 74
Common electrode side individual electrode, 76 common electrode main body, 80 strip resistors, 92, 94 overglaze, 100 connection part, 110 seal part.

Claims (2)

[Claims] 1. A strip-shaped common electrode body portion extending in the main scanning direction on an insulating substrate, and a plurality of individual electrodes extending in the multiple scanning direction on the insulating substrate at positions separated from the common electrode body portion. , A plurality of individual electrodes, or a heating resistor formed in a strip shape in the main scanning direction below or below the electrode, and a gap portion in which there is no overglaze are provided. An overglaze formed on the upper surface, a connecting portion made of a conductor disposed in a gap between the overglaze, and a seal portion formed on the upper portion of the connecting portion. A thermal head, wherein the individual electrodes are a plurality of individual electrodes that can communicate with the IC side,
Having a plurality of individual electrodes that can communicate with the common electrode body,
The gap portion is disposed so as to include an end portion on the common electrode body portion side of the individual electrode that can communicate with the common electrode body portion, and an end portion on the individual electrode side of the common electrode body portion. -The thermal head is characterized by being formed of a material capable of firing at a firing temperature of 200 ° C or less. 2. A step of forming, on a substrate, a strip-shaped common electrode main body extending in the main scanning direction and a plurality of individual electrodes isolated from the main body and extending in the sub-scanning direction; Between the step of connecting and forming a strip-shaped heating resistor extending along the main scanning direction, and between the end of the individual electrode on the side of the common electrode main body and the end of the common electrode on the side of the individual electrode. −
A step of forming an overglaze on the upper surface of the individual electrode, the heating resistor, and the common electrode main body by providing a gap portion in which there is no overglaze, and between the individual electrode and the adjacent individual electrode Pulse is applied to each half bit to modify the resistance value of the heating resistor, and a conductive material is placed in the gap of the overglaze to separate the common electrode body and individual electrodes. The method includes a step of forming a connecting portion to be connected and a step of forming a seal portion on the upper surface of the connecting portion. The connecting portion and the seal portion are made of a material that can be fired at a low temperature, and the firing temperature is 200 A method of manufacturing a thermal head at a temperature of ℃ or less.