JP4280095B2 - Manufacturing method of thermal head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a thermal head incorporated as a printer mechanism such as a word processor or a facsimile.
[0002]
[Prior art]
Conventionally, a thermal head incorporated as a printer mechanism such as a word processor is provided with a plurality of heating resistors and a pair of electrode layers on a substrate made of alumina ceramic or the like via a glass glaze layer. The thermal head has a structure covered with a protective film, and the thermal head selectively generates Joule heating of the heating resistors between the pair of electrode layers based on image data from the outside, and heats the generated heat. The thermal head is made to function by being conducted to a recording medium such as paper and forming a predetermined print on the recording medium.
[0003]
The protective film is for protecting the heating resistor and the like from wear due to sliding contact of the recording medium and corrosion due to contact with moisture contained in the atmosphere. And a SiC-based upper protective film, which are formed by a conventionally well-known thin film forming technique, specifically, a sputtering method, a CVD method, or the like.
[0005]
[Problems to be solved by the invention]
However, in this conventional thermal head, a corner is formed between the ends of the pair of electrode layers and the upper surface of the heating resistor, so that a large stress is applied to the lower protective film located in the vicinity of the corner. Is inherent. In addition, since a step portion corresponding to the corner portion is formed on the surface of the lower protective film, a large stress is inherent in the upper protective film located in the vicinity of the step portion. Further, a step portion is formed on the surface of the upper protective film.
[0006]
For this reason, when printing is performed while the recording medium is in sliding contact with the surface of the protective film, the lower protective film and the upper protective film are cracked by the sliding contact pressure, or the upper protective film and the lower protective film are easily peeled off. In addition, the heating resistor and the electrode layer may be corroded by contact with moisture in the atmosphere.
[0007]
In addition, the recording medium is scraped off by the step portion formed on the surface of the upper protective film, and a large amount of paper waste is generated, making it difficult to conduct heat from the heating resistor to the recording medium satisfactorily. It was.
[0008]
The present invention has been devised in view of the above problems, and an object thereof is to provide a method for manufacturing a high-performance thermal head capable of forming a high-quality print over a long period of time.
[0009]
[Means for Solving the Problems]
The method for manufacturing a thermal head according to the present invention deposits a heating resistor and a pair of electrode layers on a substrate, and at least a bias sputtered film on the heating resistor and the electrode layer and a non-layer deposited thereon. a lower protective layer having a bias sputtering film, the thermal head comprising sequentially laminating a cover material film, prior to the formation of the prior SL upper protective film, subjected to lapping treatment to the non-bias sputtering film surface of the lower protective layer , is characterized in that the removal of the step than the non-bias sputtering film surface.
[0010]
The manufacturing method for a thermal head of the present invention, it is preferable to form the non-bias sputtering film as a base before Fang bias sputtered film. The method for producing a thermal head according to the present invention includes a step of using a wrapping film in the wrapping process, moving the wrapping film in the main scanning direction with respect to the lower protective film, and protecting the wrapping film with the lower protective layer. The step of sliding the film in the sub-scanning direction is preferably performed a plurality of times.
[0011]
According to the present invention, the heating resistor and the pair of electrode layers are deposited on the substrate, and at least the bias sputtering film and the non-bias sputtering film deposited thereon are deposited on the heating resistor and the electrode layer. a lower protective layer having, in a thermal head composed by sequentially laminating a cover material film, prior to the formation of the prior SL upper protective film, subjected to lapping treatment to the non-bias sputtering film surface of the lower protective layer, the non-bias Since the step is removed from the surface of the sputtered film, the surface of the upper protective film deposited on the lower protective film can be formed into a smooth flat surface or curved surface. Therefore, during the recording operation, the recording medium that is in sliding contact with the surface of the upper protective film is not scraped off and a large amount of paper waste is generated, and the heat from the heating resistor can be conducted well, As a result, the thermal efficiency of the thermal head and the thermal printer can be improved and the printing quality can be improved.
[0013]
Further, according to the present invention, by forming a non-bias sputtered film as a base of the bias sputtered film , the stress inherent in the lower protective film at the boundary between the heating resistor and the pair of electrode layers becomes relatively small, Adhesiveness to the heating resistor and the pair of electrode layers is increased. Therefore, the problem that the lower protective film is peeled off from the base when the thermal head is used is effectively prevented, and the lower protective film can function for a long time.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an embodiment of the thermal head of the present invention, wherein 1 is a substrate, 3 is a heating resistor, 5 is a lower protective film, and 6 is an upper protective film.
[0015]
The substrate 1 is made of various materials such as an electrically insulating material such as alumina ceramics and glass, and a semiconductor material such as silicon, and on its upper surface, the glaze layer 2, the heating resistor 3, the electrode layer 4, the lower protective film 5, and the upper layer are formed. It functions as a support base material for supporting the protective film 6 and the like.
[0016]
When the substrate 1 is made of alumina ceramics, first, an appropriate organic solvent and solvent are added to and mixed with ceramic raw material powders such as alumina, silica, and magnesia to form a slurry, and this is made into a conventionally known doctor blade method or A ceramic green sheet is formed by adopting a calendar roll method or the like, and then the ceramic green sheet is punched into a predetermined shape and then fired at a high temperature.
[0017]
Further, on the upper surface of the substrate 1, a glaze layer 2 having a band shape along one side thereof is partially deposited and formed to a thickness of 20 μm to 60 μm.
[0018]
The glaze layer 2 is formed of a low thermal conductive material such as glass or polyimide resin, and accumulates a part of the heat generated by the heating resistor 4 in the interior thereof to maintain the thermal response characteristics of the thermal head in a good manner. Action, specifically, acts as a heat storage layer that raises the temperature of the heating resistor 4 to a predetermined temperature required for printing in a short time.
[0019]
When the glaze layer 2 is made of, for example, glass, a predetermined glass paste obtained by adding and mixing an appropriate organic solvent to glass powder is printed in a band shape on the upper surface of the head substrate 1 by screen printing or the like known in the art. Formed by applying and baking at high temperature.
[0020]
On the top of the glaze layer 2, a plurality of heating resistors 3 are linearly deposited and arranged in the main scanning direction at a density of, for example, 300 dpi (dot per inch). A pair of electrode layers 4 and 4 are electrically connected to both ends.
[0021]
The heating resistor 3 is made of a resistive thin film made of an electrical resistance material such as TaSiO, TaSiNO, TiSiO, TiSiCO, NbSiO, TiSiNi, and has a predetermined electrical resistivity, and thus has a pair of electrodes. When the power supply is applied through the layers 4 and 4, Joule heat is generated, and a predetermined temperature necessary for forming a print on the recording medium, for example, a temperature of 250 ° C. to 400 ° C. is obtained.
[0022]
On the other hand, the pair of electrode layers 4 and 4 connected to both ends of the heating resistor 3 are made of metal such as aluminum (Al) or copper (Cu), and cause the heating resistor 3 to generate Joule heat. It acts to apply a predetermined electric power required for.
[0023]
The plurality of heating resistors 3 and the pair of electrode layers 4 and 4 employ a conventionally well-known thin film technique, specifically, a sputtering method, a photolithography technique, an etching technique, etc., for example, TaSiO and Al are glazed. Formed by depositing a predetermined pattern on the upper surface of the layer 2 (thickness of the resistance thin film constituting the heating resistor 3 is 0.02 μm to 0.08 μm, thickness of the electrode layer 4 is 0.8 μm to 1.0 μm). Is done.
[0024]
An upper protective film 5 and a lower protective film 6 are sequentially deposited on the upper surfaces of the heating resistor 3 and the pair of electrode layers 4, 4.
[0025]
The lower protective film 5 is for protecting the heating resistor 3 and the pair of electrode layers 4 and 4 from corrosion due to contact with moisture or the like contained in the atmosphere and wear due to sliding contact of the recording medium. It is formed to a thickness of 6.7 μm to 7.8 μm (8.5 μm to 9.5 μm before the lapping process) with a SiON-based, SiN-based, or SiO-based inorganic material, and covers the heating resistor 3 and the pair of electrode layers 4. It is formed in this way.
[0026]
The lower protective film 5 has a three-layer structure in which a non-bias sputtered film 5a, a bias sputtered film 5b, and a non-bias sputtered film 5c are sequentially stacked. The thickness of the bias sputtered film 5b as an intermediate layer is the outermost layer. The thickness is set to 0.2 to 0.4 times the thickness of the non-bias sputtering film 5c (0.11 to 0.18 times before the lapping process).
[0027]
The lower protective film 5 preferably contains 35 atomic% to 65 atomic% of silicon, 10 atomic% to 40 atomic% of oxygen, and 15 atomic% to 40 atomic% of nitrogen. In particular, oxygen is set in the range of 10 atomic% to 40 atomic%, and the difference in oxygen content of the non-bias sputtered film 5a, bias sputtered film 5b, and non-bias sputtered film 5c is set in the range of 10 atomic%. As a result, the difference in compressive stress between the sputtered films 5a, 5b, and 5c is reduced, so that the adhesion strength can be increased and the film formation rate is increased to improve the productivity of the thermal head. Can also be provided.
[0028]
On the other hand, the upper protective film 6 is made of an inorganic material having excellent wear resistance such as SiC, SiN, and SiON, and the upper protective film 6 covers the heating resistor 3 and the pair of electrode layers 4. Thus, the heating resistor 3 and the pair of electrode layers 4 are protected from abrasion due to the sliding contact of the recording medium.
[0029]
Thus, the thermal head described above applies a predetermined electric power to the pair of electrode layers 4-4 based on the image data from the outside, selectively causes the heating resistors 3 to individually generate Joule heat, and generates the generated heat. It conducts to a recording medium such as thermal paper and functions as a thermal head by forming a predetermined print on the recording medium.
[0030]
Next, a method for forming the above-described upper protective film 5 and lower protective film 6 of the thermal head will be described in detail with reference to FIG.
[0031]
(1) First, a substrate 1 having a glaze layer 2, a heating resistor 3, and a pair of electrode layers 4 is prepared (FIG. 2A).
[0032]
(2) Next, a lower protective film 5 is deposited on the heating resistor 3 and the pair of electrode layers 4 (FIG. 2B).
[0033]
The lower protective film 5 is formed by combining conventionally known sputtering and bias sputtering.
[0034]
That is, first, the substrate 1 on which the heating resistor 3 and the pair of electrode layers 4 are deposited and the SiON target are respectively disposed on the cathode electrode and the anode electrode in the high-frequency magnetron sputtering apparatus, and then the sputtering apparatus is evacuated. At the same time, a non-bias power of 1.5 kW to 5.0 kW is applied between the cathode electrode and the anode electrode while introducing a predetermined amount of Ar (argon) gas into the device, whereby the heating resistor 3 and the pair of A non-bias sputtered film 5a is deposited on the electrode layers 4 and 4 to a thickness of 4.8 μm to 5.2 μm, and subsequently, 1.0 kW to 4 smaller than the above-mentioned non-bias power between the cathode electrode and the anode electrode. A bias power of 0.0 kW is applied to deposit the bias sputtering film 5b to a thickness of 0.4 μm to 0.6 μm, and finally A non-bias power of 1.5 kW to 5.0 kW larger than the bias power described above is applied between the cathode electrode and the anode electrode to deposit the non-bias sputtered film 5c to a thickness of 3.3 μm to 3.7 μm. As a result, the lower protective film 5 described above is formed to a thickness of 8.5 μm to 9.5 μm. Note that setting the non-bias power when forming the bias sputtered film to be smaller than the bias power when forming the non-bias sputtered film increases the deposition rate of the bias sputtered film and increases the productivity of the thermal head. It is for improving.
[0035]
Here, on the lower protective film 5, a stepped portion 5a corresponding to the shape of the corner formed by the heating resistor 3 and the pair of electrode layers 4 is formed.
[0036]
(3) Next, the step portion is removed by performing a lapping process on the lower protective film 5 (FIG. 2C).
[0037]
The wrapping treatment is performed by, for example, forming a wrapping film 7 having a configuration in which a large number of SiC particles having an average particle size of 0.5 μm to 5 μm are deposited on a base film made of polyester or the like on the non-bias sputtering film 5c of the lower protective film 5 The stepped portion on the lower protective film 5 is removed by sliding it in the sub-scanning direction (a direction orthogonal to the main scanning direction) using a platen roller disposed on the thermal head while being pressed against the surface. To do.
[0038]
At this time, since the lower protective film 5 has the non-bias sputtering film 5a as the lowermost layer, the stress at the boundary between the heating resistor 3 and the pair of electrode layers 4 is relatively small, and the heating resistor 3 and the pair of electrode layers 4 are high in adhesion. Therefore, the problem that the lower protective film 5 is peeled off from the base when the thermal head is used can be effectively prevented, and the lower protective film 5 can function for a long time.
[0039]
Further, since the thickness of the bias sputtering film 5b, which is an intermediate layer of the lower protective film 5, is set to 0.11 to 0.18 times the thickness of the outermost non-bias sputtering film 5a, the sliding contact pressure by the lapping process is set. Even when the non-bias sputter film 5c does not peel off from the bias sputter film 5b or the bias sputter film 5b peels off from the non-bias sputter film 5a due to the sliding contact pressure, the yield of the thermal head is not increased. It can be used for improvement.
[0040]
Here, if the thickness of the bias sputtering film 5b, which is an intermediate layer of the lower protective film 5, is smaller than 0.11 times the thickness of the outermost non-bias sputtering film 5c, the step coverage of the bias sputtering film 5b deteriorates. However, the adhesion strength of the bias sputtered film 5c deposited thereon tends to be low, while the thickness of the bias sputtered film 5b that is an intermediate layer of the lower protective film 5 is less than the thickness of the non-bias sputtered film 5c. If it is larger than 18 times, the compressive stress of the bias sputtered film 5b becomes too large, and the non-bias sputtered film 5c tends to be more easily separated from the bias sputtered film 5b. Therefore, it is important to set the thickness of the bias sputtering film 5b, which is an intermediate layer of the lower protective film 5, to be 0.11 to 0.18 times the thickness of the outermost non-bias sputtering film 5a. is there.
[0041]
Further, when the wrapping process is performed, the wrapping film 7 is not slid in the sub-scanning direction at the same place, but is moved in the main scanning direction with respect to the lower protective film 5, and then the wrapping film 7 is moved to the lower protective film 5. When the surface state of the wrapping film 7 varies depending on the region, or the wrapping film 7 is slidably contacted in the sub-scanning direction and moved again in the main scanning direction with respect to the lower protective film 5 again. Even when the flatness of the platen roller that moves the surface is different for each region, it is possible to effectively prevent a large difference in the way the surface of the lower protective film 5 (non-bias sputtering film 5c) is scraped. Therefore, the wrapping film 7 is not always slid in the sub-scanning direction at the same position, but the wrapping film 7 is moved in the main scanning direction, and then the wrapping film 7 is slid in the sub-scanning direction several times. It is preferable.
[0042]
The thickness of the non-bias sputtered film 5c after lapping is 1.5 μm to 2.0 μm, and the thickness of the bias sputtered film is 0.2 to 0.4 times the thickness of the non-bias sputtered film.
[0043]
(4) Finally, the upper protective film 6 is deposited on the lower protective film 5 (FIG. 2D).
[0044]
The upper protective film 6 is formed to a thickness of 2.5 μm to 3.5 μm by employing a conventionally well-known thin film forming technique, specifically, a conventionally known sputtering, CVD method or the like.
[0045]
At this time, since the step portion on the lower protective film 5 is removed in the step (3), the surface of the upper protective film 6 deposited on the lower protective film 5 can be formed into a smooth flat surface or curved surface. it can. Therefore, during the recording operation, the recording medium that is in sliding contact with the surface of the upper protective film 6 is not scraped off and a large amount of paper waste is not generated, and the heat from the heating resistor 3 can be conducted well. As a result, the thermal efficiency of the thermal head and the thermal printer can be improved and the print quality can be improved.
[0046]
When the upper protective film 6 is made of a SiC-based inorganic material, the SiC-based inorganic material tends to be brittle. Therefore, when the upper protective film 6 is formed by the bias sputtering method, the internal stress of the bias sputtered film is large. As a result, the upper protective film 6 itself becomes very brittle, and it may be difficult to maintain high wear resistance. Therefore, when the upper protective film 6 is made of a SiC-based inorganic material, it is preferably formed by a conventionally known non-bias sputtering method.
[0047]
The present invention is not limited to the above-described embodiment, and various modifications and improvements can be made without departing from the scope of the present invention.
[0048]
For example, in the above-described embodiment, the glaze layer 2 is partially formed on the upper surface of the substrate 1. However, instead of this, as shown in FIG. Absent.
[0049]
In the above-described embodiment, the surface of the upper protective film 6 may be lapped, and in this case, the surface of the upper protective film can be further smoothed to effectively prevent the sticking of the recording medium and the like. is there.
[0050]
【The invention's effect】
According to the present invention, the surface of the upper protective film deposited on the lower protective film can be formed into a smooth flat surface or curved surface, and is in sliding contact with the surface of the upper protective film during the recording operation. The recording medium is not scraped off and a large amount of paper waste is not generated, and the heat from the heating resistor can be conducted well. As a result, the thermal efficiency of the thermal head and the thermal printer can be improved and the printing quality can be improved.
[0051]
Further, according to the present invention, by forming a non-bias sputtered film as a base of the bias sputtered film, the stress inherent in the lower protective film at the boundary between the heating resistor and the pair of electrode layers becomes relatively small, Adhesiveness to the heating resistor and the pair of electrode layers is increased. Therefore, the problem that the lower protective film is peeled off from the base when the thermal head is used is effectively prevented, and the lower protective film can function for a long time.
[0052]
According to the invention, in the wrapping process, a wrapping film is used, the wrapping film is moved in the main scanning direction with respect to the lower layer protective film, and the wrapping film is subordinate to the lower layer protective film. The surface state of the wrapping film varies from region to region, or the flatness of, for example, a platen roller that moves the wrapping film varies from region to region, by performing the sliding contact in the scanning direction a plurality of times. However, it is possible to effectively prevent a large difference in how the surface of the non-bias sputtered film is scraped .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a thermal head manufactured by a manufacturing method of the present invention.
FIG. 2 is a cross-sectional view of each step for explaining a manufacturing method according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Glaze layer 3 ... Heating resistor 4 ... Electrode layer 5 ... Lower layer protective film 5a ... Non-bias sputtering film 5b ... Bias sputtering film 5c ... Non-bias sputtered film 6 ... upper layer protective film 7 ... wrapping film

Claims (3)

A heating resistor and a pair of electrode layers are deposited on the substrate, and a lower protective film having at least a bias sputtering film and a non-bias sputtering film deposited thereon on the heating resistor and the electrode layer, In the thermal head formed by sequentially laminating the upper protective film ,
Prior to the formation of the prior SL upper protective film, subjected to lapping treatment to the non-bias sputtering film surface of the lower protective layer, a method of manufacturing a thermal head is characterized in that the removal of the step than the non-bias sputtering film surface. A thermal head manufacturing method according to claim 1, characterized in that to form a non-bias sputtering film as a base before Fang bias sputtered film. In the wrapping process, using a wrapping film, moving the wrapping film in the main scanning direction with respect to the lower protective film, and sliding the wrapping film in the sub-scanning direction with respect to the lower protective film And the thermal head manufacturing method according to claim 1, wherein the thermal head is performed a plurality of times.

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