JPH0592595A - Manufacture of thermal head - Google Patents

Abstract

PURPOSE:To improve image print quality and dimensional precision in manufacture by a method wherein a metal layer is made on an insulating substrate, it is etched so as to form a common electrode member and individual electrode members, thereafter, these are etched so as to form a plurality of heating elements and a common electrode. CONSTITUTION:In a thermal head 17, a glazed layer 12, a heat generating resistor layer 13, an electrode layer consisting of a plurality of individual electrodes 14a and a common electrode 14b partitioned by a notch 26, and a protective layer 15 for covering these members are formed in sequence on an insulating substrate 11. In this case, at manufacturing, a metallic layer 22 is firstly formed on the insulating substrate 11. The metal layer 22 is etched so as to form a common electrode member 25 and a plurality of individual electrode members 28 which are in parallel with each other are formed, respectively. The individual electrode members 28 and the common electrode member 25 are etched. The heat generating resistor layer 13 is exposed at an area 27 of the individual electrode members 28 so as to form a plurality of heating elements 16. Further, the common electrode 14b having a predetermined width is formed on the common electrode member 25.

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 mounted on a thermal printer which is widely used as, for example, a print output device of a word processor.

[0002]

2. Description of the Related Art FIG. 6 is a typical prior art cross section. In the thermal head 7, the glaze layer 2 is formed on the ceramic electrically insulating substrate 1, the heating resistor layer 3 is formed on the substrate 1 and the glaze layer 2, and a plurality of layers are formed by photoetching on the heating resistor layer 3. The individual electrode 4a and the common electrode 4b are formed with a space between them, and these electrode 4
The heating resistor layer 3 is exposed between a and 4b, and the printing element 6 is formed. In order to prevent abrasion of the electrodes 4a and 4b and the printing element 6 of the heating resistor layer 3 during printing, and to prevent oxidation of the heating resistor layer 3 in the printing element 6 due to heat generation,
The protective film 5 is formed. Due to the selective heat generation of the heating resistor layer 3 in the printing element 6, the heat is transmitted through the protective film 5 to add heat to the ink ribbon or heat to the thermal paper, thereby printing is performed.

In the manufacturing process of such a thermal head 7, the glaze layer 2 is formed on the substrate 1, and the heating resistor layer 3 and the metal layer 4 forming the electrodes 4a and 4b are sputtered on the substrate 1. And the like. Next, as shown in FIG. 7, a plurality of notches 8 extending in two layers of the heating resistor layer 3 and the metal layer 4 and parallel to each other are formed by a method such as etching. Next, with respect to the laminated body of the heating resistor layer 3 and the metal layer at this stage, the formation region 9 of the printing element 6 shown by the broken line in FIG.
Remove only. Thereby, the individual electrode 4a and the common electrode 4
b is divided, and a plurality of printing elements 6 are linearly arranged so as to be sandwiched between them. After that, a polishing process as shown in FIG. 6 is performed on the end portion of the substrate 1 so that the distance L1 between the printing element 6 and the end portion of the substrate 1 is set to a predetermined dimension of, for example, 350 μm, and removed. The portion 10 is polished and removed.

On the other hand, in recent years, the distance L1 has been made as small as possible because of the demand for higher image quality and higher speed of the thermal printer. Assuming that thermal transfer is performed using an ink ribbon, for example, the time until the ink ribbon is peeled off from the protective film 5 depends on the distance from the central position 6a of the printing element 6 to the end 1a of the substrate 1. L
Corresponds to 1. If this distance L1 is too long, the once melted ink of the ink ribbon starts to solidify again, so that printing is performed with many voids, that is, there are many portions where the ink does not adhere sufficiently to the recording paper, and the printing quality deteriorates. Resulting in. Therefore, it is necessary to make this distance L1 as short as possible.

On the other hand, if the printing operation is speeded up, it is necessary to increase the current density required for one printing, and it is necessary to increase the width of the common electrode 4b in the left-right direction in FIG. Therefore, the end 8a of the notch 8 on the side of the common electrode 4b is shifted to the left in FIG. 7, and each printing element 6 is completely divided by the notch 8 as shown in FIG. As shown in 7 (1), a technique has been proposed in which the printing elements 6 are connected on the common electrode 4b side. As an example of such a conventional example, there is JP-A-3-61551. This conventional example is intended to improve the print density by improving the heat distribution of each print element 6 in the vertical direction in FIG.

[0006]

On the other hand, if an attempt is made to speed up the printing operation in the thermal head 7 as described above, the current density supplied to each printing element 6 increases, and therefore the common electrode 4b. In FIG. 7, it is necessary to make the width in the left-right direction as wide as possible. As described above, when it is intended to form the printing element 6 by etching only the metal layer 4 with respect to the laminated body of the heating resistor layer 3 and the metal layer 4 at the stage where the notch 8 is formed as described above, The etching process is performed by leaving a region on the insulating substrate 1 where the printing element 6 is to be formed and forming a mask made of a synthetic resin material or the like to cover the remaining region.

When a through hole corresponding to the formation region 9 is formed in this mask, due to an alignment error in determining the position of the formation region 9, the printing element 6 should be originally formed in a region shown by a broken line in FIG. An actual printing element 6 is formed on the side of the common electrode 4b as shown in FIG. 7 (1) with respect to the formation area 9 shown, or is formed on the side of the individual electrode 4a as shown in FIG. 7 (2). It may be formed with a shift.

In the case of FIG. 7B, the formation region 9 is shown in FIG.
Even if it shifts to the individual electrode 4a side of (2), the end portion 8 of the notch 8
It is known that “a” serves as a guideline for alignment, and a large displacement is avoided, and in the case of such displacement, the common electrode 4b becomes wide, and the thermal head 7 as a product is relatively free from defects. ing.

On the other hand, when the formation region 9 is displaced toward the common electrode 4b side, the width of the common electrode 4b in the left-right direction in FIG.
The wiring resistance of the common electrode 4b becomes large, and the current density becomes excessive, which causes a large voltage drop and power loss. As a result, as the number of printing elements 6 that generate heat at the same time increases, the printing density decreases, and the printing quality is greatly reduced, such as the printed characters are blurred.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above technical problems and to provide a method of manufacturing a thermal head which can significantly improve the printing quality and the dimensional accuracy in manufacturing.

[0011]

According to the present invention, a glaze layer, a resistor layer, an electrode layer composed of a plurality of individual electrodes and a common electrode which are separated from each other by interposing a notch, and an electrode layer on the insulating substrate. In a method of manufacturing a thermal head in which a protective layer to be coated is sequentially formed, a metal layer is formed on an insulating substrate on which a glaze layer and a resistor layer are formed on a main surface, and then the metal layer is etched. A step of processing to form a common electrode member and a plurality of individual electrode members parallel to each other; and etching the individual electrode member and the common electrode member to expose the resistor layer in the region of the individual electrode member And the step of forming a common electrode having a predetermined width on the common electrode member.

[0012]

The thermal head according to the present invention comprises a glaze layer, a resistor layer, an electrode layer composed of a plurality of individual electrodes and a common electrode which are separated from each other by interposing notches, and a protective layer covering these layers on an insulating substrate. And layers are sequentially formed. At this time, a metal layer is formed on an insulating substrate on which a glaze layer and a resistor layer are formed on the main surface, and a plurality of notches parallel to each other are formed to form a plurality of individual electrode members and a common electrode. And forming a plurality of heating elements by exposing the resistor layer in the formation region including the region of the individual electrode member in the region extending between the individual electrode member and the common electrode member. A groove parallel to the arrangement direction of the heating elements is formed at a predetermined distance from the end on the common electrode side of the area where the heating elements are formed.

Therefore, the width of the common electrode in the direction perpendicular to the arrangement direction of the heating elements is defined by the interval between the end of the plurality of notches on the common electrode side or the end of the formation region on the common electrode side and the groove. To be done. This interval is fixed on the mask used for forming the groove portion and the like. Therefore, even if the formation region is deviated in both directions intersecting the arrangement direction of the heating elements, the groove portion is interlocked with this. Since the formation position of is moved, a common electrode having a constant width can be obtained.

As a result, it is possible to prevent a situation in which the common electrode is undesirably narrowed to cause a large voltage drop or power loss with respect to the current flowing through the common electrode, and it is possible to prevent the print quality from being deteriorated. ..

Further, when the end portion of the insulating substrate such as the common electrode is polished, the groove portion can be used as a guide for determining the progress of polishing. As a result, the dimensional accuracy in manufacturing is significantly improved.

[0016]

1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a plan view of the embodiment shown in FIG. In the thermal head 17 for a serial printer, a glaze layer 12 is formed on a substrate 11 made of an electrically insulating material such as alumina ceramic. This glaze layer 12
Is made of, for example, glass containing SiO ₂ as a main component. The heating resistor layer 13 is formed on the glaze layer 12 and the substrate 11.
Is formed. Further, a metal layer 14 made of a metal, for example, a material such as aluminum or copper is formed over the entire surface, and the individual electrode 14a and the common electrode 14b are formed by the photoetching technique. Between the plurality of individual electrodes 14a and the common electrode 14b common to them, the heating resistor layer 13 is exposed and the printing element 16 is formed.

A protective film 15 is formed on the common electrodes 14a and 14b, the printing element 16 and other surfaces. The protective film 15 is formed of, for example, Si ₃ N ₄ or Ta ₂
It consists of O ₅ etc. The protective film 15 functions to prevent abrasion of the individual electrode 14a and the common electrode 14b during printing and also to prevent oxidation of the heating resistor layer 13 in the printing element 16 due to heat generation.

The common electrode 14b has a width W in the sub-scanning direction.
1 (for example, 50 μm), and the common electrode 14
b and a groove 20 having a width W2 (for example, 20 μm) where the heating resistor layer 13 is exposed are formed on the end side of the substrate 11 and the common electrode 14b and the same material and the same manufacturing as the common electrode 14b with the groove 20 separated. Width W3 (eg 35
μm) dummy line 21 is formed.

FIG. 3 is a process diagram for explaining the manufacturing process of the thermal head 17 of this embodiment, and FIGS. 4 and 5 are diagrams for explaining this manufacturing process. In step a1, FIG.
As shown in (1), the glaze layer 12 made of glass or the like is formed on the substrate 11. In step a2, the heating resistor layer 13 and the metal layer 22 made of, for example, aluminum are formed on the substrate 11 by a technique such as sputtering.

In step a3, the heating resistor layer 13 and the metal layer 22 are both etched in the same step to form a peripheral portion 23 of the substrate 11, and a dummy line formed from the metal layer 22 as described later. The common electrode member 25 is formed to have a width that can include the dummy line formation region 24 in which is formed. Further, in order to form the plurality of individual electrodes 14a, a plurality of notches 26 having a width W5 are formed in parallel with each other with a space W4 therebetween. The common electrode member 2 of this notch 26
The fifth-side end portion 26a is formed so as to be located in the printing element forming region 27 in which the printing element 16 is formed. As a result, a plurality of individual electrode members 28 are formed.

In step a4, with respect to the substrate 11 in the manufacturing stage shown in FIG. 4 (4), the metal within the printing element forming region 27 and the groove forming region 29 shown by the two-dot chain line in FIG. 4 (4) is formed. Only layer 22 is etched. As a result, as shown in FIG. 5A and FIG. 2, the heating resistor layer 23 is exposed for each individual electrode 14 a in the range extending over the individual electrode 28 and the common electrode member 25, and the printing element 16 is formed. .. A groove 20 having a width W2 is formed at a distance W1 shown in FIG. 2 from the printing element 16, and a dummy line 21 having a strip-shaped metal layer 22 is formed on the opposite side of the groove 20 from the common electrode 14b. It That is, the printing element 16 and the groove 20 are formed by the same mask that exposes the photoresist in a photo process using a photoresist or the like used when performing such etching.

In step a5, as shown in FIG. 5B, the protective film 15 is formed on the substrate 11 in the manufacturing stage. In step a6, the distance L2 between the central position of the heating element 16 and the end of the insulating substrate 11 is set to a desired value as small as possible for the purpose of improving the printing quality of the thermal head 17 and increasing the speed. In addition, the end side of the substrate 11 is shown in FIG.
As shown in (2), polishing is performed from the original end 11a of the substrate 11 to the end face 30.

At this time, when the polishing position on the front surface side of the substrate 11 reaches the common electrode 14b, the common electrode 14b is polished.
Is undesirably narrowed and the area is reduced, resulting in the problems described in the section of the prior art. Therefore, in this embodiment, when performing the polishing process, the dummy line 21
Use as a guide. That is, both the common electrode 14b and the dummy line 21 are made of a metal such as aluminum, and are visually recognized as white. On the other hand, in the groove 20, the metal layer 22 is peeled off, and the heating resistor layer 13 is seen as black.

Therefore, the polishing work is performed on the dummy line 21.
Is on the way, or the groove 20 is in the dummy line 21.
It is sandwiched between the common electrode 14b and the common electrode 14b, and the process is finished with a degree of being clearly visible. If the polishing is excessive, the groove 20 disappears and the polishing member enters the common electrode 14b, and the common electrode 14b becomes narrow, which causes a problem as described in the section of the prior art. Prevent the occurrence of serious problems.

As described above, in this embodiment, the heating resistor layer 13 and the metal layer 22 are formed on the substrate 11, and the notch 26 is formed.
The printing element formation region 2
7 and the groove formation region 29 were etched using the same photomask. As a result, the photomask is misaligned, and the printing element forming area 27 is formed in FIG.
Even if it shifts to the right side in (4), the groove 20 shifts to the right side in FIG. 4 similarly, and the width W1 in the left-right direction in FIG. 2 of the common electrode 14b sandwiched between the printing element forming region 27 and the groove forming region 29. Is constant. As a result, it is possible to prevent the width of the common electrode from being undesirably reduced and the print quality from being deteriorated, as described in the section of the related art.

Further, in the polishing process for manufacturing the thermal head 17, the dummy line 21 and the groove 20 serve as a measure of the progress of polishing, and the polishing operation can be performed with high accuracy.

[0027]

As described above, the thermal head according to the present invention has a glaze layer, a resistor layer, and an electrode layer composed of a plurality of individual electrodes and a common electrode which are separated from each other by interposing notches, on an insulating substrate. And a protective layer that covers these and are sequentially formed. At this time, a metal layer is formed on the insulating substrate on which the glaze layer and the resistor layer are formed on the main surface,
Forming a plurality of notches parallel to each other to form a plurality of individual electrode members and a common electrode member, in the formation region including the region of the individual electrode member in the region across the individual electrode member and the common electrode member, Exposing the resistor layer to form multiple heating elements,
At the same time, in the common electrode member, a groove parallel to the arrangement direction of the heating elements is formed at a predetermined distance from the end on the common electrode side of the area where the heating elements are formed.

Therefore, the width of the common electrode in the direction perpendicular to the arrangement direction of the heating elements is determined by the end of the plurality of notches on the common electrode side or the interval between the end of the formation region on the common electrode side and the groove. To be done. This interval is fixed on the mask used for forming the groove portion and the like. Therefore, even if the formation region is deviated in both directions intersecting the arrangement direction of the heating elements, the groove portion is interlocked with this. Since the formation position of is moved, a common electrode having a constant width can be obtained. As a result, it is possible to prevent a situation in which the common electrode becomes undesirably narrow and causes a large voltage drop or power loss with respect to the current flowing through the common electrode, and it is possible to prevent the print quality from being deteriorated.

Further, when the end portion of the insulating substrate or the like on the common electrode side is polished, the degree of progress of polishing can be determined by using the groove portion as a guide. As a result, the dimensional accuracy in manufacturing is significantly improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a thermal head 17 according to an embodiment of the present invention.

FIG. 2 is a plan view of a thermal head 17.

FIG. 3 is a process drawing showing a manufacturing process of the thermal head 17 of the embodiment of the present invention.

FIG. 4 is a diagram illustrating this manufacturing process.

FIG. 5 is a diagram illustrating this manufacturing process.

FIG. 6 is a cross-sectional view of a conventional thermal head 7.

FIG. 7 is a plan view illustrating a problem of a conventional example.

[Explanation of symbols]

 11 substrate 11a end part 13 heating resistor layer 14a individual electrode 14b common electrode 16 printing element 17 thermal head 20 groove 21 dummy line 22 metal layer 26 notch 27 printing element forming area

Claims (1)

[Claims] 1. A glaze layer, a resistor layer, an electrode layer composed of a plurality of individual electrodes and a common electrode which are separated from each other by interposing notches, and a protective layer which covers these layers are sequentially formed on an insulating substrate. In the method of manufacturing a thermal head, a metal layer is formed on an insulating substrate on which a glaze layer and a resistor layer are formed on the main surface, and then the metal layer is subjected to an etching process so as to interact with the common electrode member. A step of forming a plurality of individual electrode members parallel to each other, and etching the individual electrode member and the common electrode member, exposing the resistor layer in the region of the individual electrode members to form a plurality of heating elements, And a step of forming a common electrode of a predetermined width on the common electrode member.