Method for manufacturing heating substrate for thin film thermal print head

Abstract

The present application provides a method for manufacturing a heating substrate for a thin film thermal print head, which solves the technical problem that the existing thermal print head cannot avoid the occurrence of electrochemical corrosion of the thermal print head and reduce the thickness of the insulating film protective layer; it includes: an insulating protective layer project: on the surface of the insulating substrate provided with a heating resistor and an electrode wire, an insulating film protective layer is at least partially formed; it also includes: a high-resistance wear-resistant protective layer project: a high-resistance wear-resistant protective layer with a thickness of 10 to 1000nm and a resistivity of not less than 100Ω·m is formed on the insulating film protective layer; a low-resistance wear-resistant protective layer project: a high-resistance wear-resistant protective layer with a thickness of 1000 to 6000nm and a resistivity of 10 ‑3 Ω·m~10 ‑1 The invention is widely used in the field of thermal printing technology.

Description

Technical Field

[0001] The present application relates to a thermal print head, and more specifically, to a method for manufacturing a heating substrate for a thin film thermal print head. Background Art

[0002] We know that the heating substrate for the thin film thermal print head includes an insulating substrate with an amorphous glaze coating formed on the surface, a common electrode wire partially arranged on the surface of the insulating substrate or the glaze coating, a heating resistor layer is arranged on the amorphous glaze coating, and a conductor layer covers the heating resistor layer. During the production process, the conductor layer is formed into an electrode wire through photoengraving technology, and the resistor layer is formed into a plurality of heating resistors arranged along the main printing direction. Then, a non-conductive material whose main component is silicon is used to form an insulating film protective layer with a thickness of several thousand nm on the common electrode wire, the heating resistor and at least part of the electrode wire through sputtering. In order to enhance the wear resistance of the thermal print head and prevent static electricity generated by friction between the thermal print head and the printing consumables during the printing process, a conductive material is usually used to stack on the insulating film protective layer to form a conductive hard protective layer of several thousand nm. For example, a composite material whose main components are carbon and silicon carbide can be used to form a conductive hard protective layer with high wear resistance.

[0003] However, the several thousand nm insulating film protective layer of the above-mentioned thermal print head usually needs to be formed by radio frequency magnetron sputtering because it uses non-conductive materials whose main component is silicon, such as silicon dioxide (SiO2), silicon oxynitride (SiON), sialon ceramics (SiAlON), etc. However, radio frequency magnetron sputtering has the problem of low deposition rate compared with DC magnetron sputtering or medium frequency magnetron sputtering. Moreover, the non-conductive material whose main component is silicon is easy to peel off and form foreign matter after being accumulated to a certain thickness in the magnetron sputtering equipment. The foreign matter will greatly increase the probability of pinhole defects in the insulating film protective layer.

[0004] When a conductive hard protective layer is directly laminated on an insulating film protective layer with pinhole defects, the problem of insufficient insulation impedance between the conductive hard protective layer and the electrode wire may easily occur. In this way, when the thermal print head is powered on, a high potential close to the printing voltage of the thermal print head may appear on the conductive hard protective layer, causing the thermal print head to enter an electrochemical corrosion damage mode in a humid printing environment.

[0005] The problem of non-conductive materials in the above-mentioned magnetron sputtering equipment being prone to peeling off after accumulating to a certain thickness can be improved by regularly performing maintenance and cleaning on the chamber, but the frequency of maintenance and cleaning is proportional to the product of the thickness of the insulating film protective layer and the number of production times. The maintenance frequency can be reduced by reducing the thickness of the insulating film protective layer, but the occurrence rate of insufficient insulation impedance between the conductive hard protective layer and the electrode wire may increase.

[0006] To address the problem that non-conductive materials in magnetron sputtering equipment tend to peel off and form foreign matter after accumulating to a certain thickness, which increases the probability of pinhole defects in the insulating film protective layer, the foreign matter can be removed by grinding, but this will increase costs. Summary of the invention

[0007] In order to solve the above problems, the technical solution adopted by the present application is: to provide a method for manufacturing a heating substrate for a thin film thermal print head, including: an insulating protective layer project: forming an insulating thin film protective layer at least partially on the surface of the insulating substrate where a heating resistor and an electrode wire are provided; and also including:

[0008] High-resistance wear-resistant protective layer engineering: using a target material whose main component is carbon and whose additive component is silicon carbide, using DC or AC magnetron sputtering equipment, introducing nitrogen, or a mixture of nitrogen and oxygen, or a mixture of nitrogen and argon as working gas, to form a high-resistance wear-resistant protective layer with a thickness of 10 to 1000nm and a resistivity of not less than 100Ω·m on the insulating film protective layer;

[0009] Low resistance wear-resistant protective layer engineering: using a target material whose main component is carbon and whose additional component is silicon carbide, using DC or AC magnetron sputtering equipment, introducing argon as the working gas, a high resistance wear-resistant protective layer with a thickness of 1000 to 6000nm and a resistivity of 10 -3 Ω·m~10 -1 Ω·m low resistance wear-resistant protective layer.

[0010] Preferably, in the high-resistance and wear-resistant protective layer, the atomic content percentage of nitrogen or the sum of the atomic content percentages of nitrogen and oxygen is not less than 20%.

[0011] Preferably, in the high-resistance wear-resistant protective layer project, in the mixed gas of nitrogen and oxygen, the oxygen accounts for no more than 50% of the total flow rate.

[0012] Preferably, in the high-resistance wear-resistant protective layer project, in the mixed gas of nitrogen and argon, the argon gas accounts for no more than 50% of the total flow rate.

[0013] Preferably, the thickness of the insulating film protective layer is 500-6000 nm.

[0014] Preferably, after the low-resistance wear-resistant protective layer engineering, it also includes:

[0015] Organic resin layer process: Using a solder resist material with epoxy resin as the main component, an organic resin layer is formed at least in a set area on an insulating substrate by a method of heating and curing after printing.

[0016] Preferably, before the insulating protective layer engineering, it also includes:

[0017] Glazing Engineering: Forming a glaze coating on one surface of an insulating substrate;

[0018] Common electrode engineering: forming a common electrode on the surface of the insulating substrate and the glaze coating;

[0019] Metal film engineering: forming a heating resistor layer on the insulating substrate and the glaze coating, and forming an electrode conductor layer on the heating resistor layer;

[0020] Graphical engineering: Using photolithography combined with etching, the heating resistor layer and the electrode conductor layer are formed into several heating resistors and electrode conductors.

[0021] The present invention also provides a heating substrate for a thermal print head that prevents unexpected heating, comprising an insulating substrate; a glaze coating formed at least partially on the surface of the insulating substrate; electrode wires formed on the surfaces of the insulating substrate and the glaze coating, the electrode wires comprising a common electrode and individual electrodes; a heating resistor that is powered by the common electrode and the individual electrodes; an insulating film protective layer covering the heating resistor and at least a portion of the electrode wire connected to the heating resistor; a high-resistance wear-resistant protective layer covering at least a portion of the insulating film protective layer; a low-resistance wear-resistant protective layer covering the high-resistance wear-resistant protective layer;

[0022] The resistivity ratio of the high-resistance wear-resistant protective layer to the low-resistance wear-resistant protective layer is not less than 1000.

[0023] Preferably, the high-resistance wear-resistant protective layer contains at least one of carbon nitride, silicon nitride and silicon oxide in addition to the material of the low-resistance wear-resistant protective layer.

[0024] The beneficial effect of the present invention is that the heating substrate for the thin film thermal print head formed by the method of the present application has a high resistance wear-resistant protective layer with a deposition thickness of 10 to 1000nm and a resistivity of not less than 100Ω·m between the low resistance wear-resistant protective layer and the insulating film protective layer. Even if the insulating film protective layer has defects such as pinholes, the impedance between the electrode wire and the low resistance wear-resistant protective layer will still be greater than tens of megohms. In this way, when the thermal print head is powered on, the potential on the low resistance wear-resistant protective layer will be much lower than the printing voltage of the thermal print head, thereby achieving the effect of reducing the probability of electrochemical corrosion of the thin film thermal print head. In addition, the thickness of the insulating film protective layer is between 500 and 6000nm, which can not only reduce the thickness of the insulating film protective layer, but also avoid the problem of increasing the probability of insufficient impedance between the electrode wire and the low resistance wear-resistant protective layer. In addition, the thickness of the insulating film protective layer is reduced, which reduces the maintenance frequency of the magnetron sputtering equipment and the probability of pinhole defects in the insulating film protective layer, thereby reducing the equipment maintenance cost and the grinding and processing cost of the insulating film protective layer, which is conducive to large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0026] Figure 1 is a simplified manufacturing flow chart of the present invention;

[0027] Figure 2 is a schematic cross-sectional view of the heating substrate of the present invention;

[0028] Figure 3 It is a plan view of the heating substrate of the present invention.

[0029] Explanation of symbols in the figure:

[0030] 01. Heating substrate; 10. Insulating substrate; 20. Glaze coating; 30. Common electrode; 40. Heating resistor layer; 41. Heating resistor; 50. Electrode conductor layer; 51. Electrode wire; 60. Insulating film protective layer; 70. High resistance and wear-resistant protective layer; 80. Low resistance and wear-resistant protective layer; 90. Organic resin layer. DETAILED DESCRIPTION

[0031] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0032] The method for manufacturing the heating substrate for the thin film thermal print head provided in the embodiment of the present application is now described.

[0033] See also Figure 1 The manufacturing method of the heating substrate for the thin film thermal print head of the present embodiment includes a glazing process P1 for forming a heat-resistant glaze coating 20 on one surface of an insulating substrate 10, a common electrode process P2 for forming a common electrode 30 on the insulating substrate 10, a film forming process P3 for forming a heating resistor layer 40 and an electrode conductor layer 50 on the insulating substrate 10 and the heat-resistant glaze coating 20, a graphic process P4 for forming the heating resistor layer 40 and the electrode conductor layer 51 by using a photolithography method, an insulating protective layer process P5 for forming an insulating thin film protective layer 60, a high-resistance wear-resistant protective layer process P6 for forming a high-resistance wear-resistant protective layer 70, a low-resistance wear-resistant protective layer process P7 for forming a low-resistance wear-resistant protective layer 80, and an organic resin layer process P8 for forming an organic resin layer 90. By using the above manufacturing process, a structure such as Figure 2 and Figure 3 The high-performance thin-film thermal print head heat generating substrate shown.

[0034] Furthermore, in one embodiment, the glazing process P1 is to form a heat storage glaze coating 20 partially on one surface of the insulating substrate 10 having a parallel plate shape and a main component of aluminum oxide by printing and sintering a glass glaze slurry;

[0035] The common electrode process P2 uses thick film silver paste and adopts a printing and sintering method to form a common electrode 30;

[0036] The metal film process P3 is to form a heating resistor layer 40 on the insulating substrate 10 and the glaze coating 20 by magnetron sputtering using a metal ceramic target, such as a composite material target formed by tantalum and silicon dioxide, and to form an electrode conductor layer 50 on the heating resistor layer 40 by magnetron sputtering using an aluminum target;

[0037] The patterning process P4 is to design and manufacture a photolithography plate for photolithography in advance according to necessary information such as printing resolution, and to form a plurality of heating resistors 41 and electrode conductors 51 from the heating resistor layer 40 and the electrode conductor layer 50 by means of photolithography combined with etching;

[0038] Insulation protection layer process P5 uses silicon oxynitride or Sialon ceramic composite target material, uses argon as plasma generating gas, and adopts radio frequency magnetron sputtering method to at least partially form an insulation film protection layer 60 on the surface of the insulation substrate 10 provided with the heating resistor 41 and the electrode wire 51;

[0039] The high-resistance wear-resistant protective layer project P6 uses a target material whose main component is carbon and whose additional component is silicon carbide, and uses a DC or AC magnetron sputtering device to form a high-resistance wear-resistant protective layer 70 with a thickness of 10 to 1000 nm and a resistivity of not less than 100Ω·m in a set area on the surface of the insulating film protective layer 60;

[0040] The low-resistance wear-resistant protective layer project P7 uses a target material whose main component is carbon and whose additional component is silicon carbide. It uses the same DC or AC magnetron sputtering equipment and uses argon as the working gas to form a layer with a thickness of between 1000 and 6000 nm and a resistivity of 10 -3 Ω·m~10 -1 Ω·m low-resistance wear-resistant protective layer 80; if the thickness of the low-resistance wear-resistant protective layer 80 is less than 1000nm, there may be a problem of insufficient wear resistance. If the thickness is greater than 6000nm, the heat capacity around the heating resistor 40 will increase, affecting the printing speed and printing effect of the thermal print head.

[0041] The organic resin layer project P8 uses a solder resist material with epoxy resin as the main component, and forms an organic resin layer 90 by a method of post-printing heating and curing, at least in a set area on the insulating substrate 10, and in an area away from the heating resistor 40 and where the insulating film protective layer 60 is not easily deposited.

[0042] In this way, the heating substrate for the thin film thermal print head is formed. Under the condition of using the same carbon and silicon carbide target materials and utilizing the same DC or AC magnetron sputtering equipment, the resistivity of the high-resistance wear-resistant protective layer 70 formed is more than 1000 times higher than the resistivity of the low-resistance wear-resistant protective layer 80. In this way, even if the insulating film protective layer 60 has defects such as pinholes, the impedance between the electrode wire 51 and the low-resistance wear-resistant protective layer 80 will still be greater than tens of megohms, and the low-resistance wear-resistant protective layer 80 no longer has a potential close to the working potential of the thermal print head, thereby fundamentally solving the problem of electrochemical corrosion of the thermal print head in a humid printing environment.

[0043] Furthermore, in one embodiment, the insulating film protective layer 60 is formed by at least partially depositing on the surface of the heating resistor 41, the electrode wire 51, the glaze coating 20 and the insulating substrate 10. The thickness of the insulating film protective layer 60 can be set between 500 and 6000 nm according to the color development characteristics of different printing media. When the thickness of the insulating film protective layer 60 is less than 500 nm, the breakdown voltage of the insulating film protective layer 60 will be lower than 50V, and there is a risk of insufficient tolerance; when the thickness of the insulating film protective layer 60 is greater than 6000 nm, the heat capacity around the heating resistor 41 will increase, affecting the printing speed and printing effect of the thermal print head. Selecting the thickness of the insulating film protective layer 60 within the range of 500 to 6000 nm can not only reduce the thickness of the insulating film protective layer 60, but also avoid the problem of increased probability of insufficient impedance between the electrode wire 51 and the low-resistance wear-resistant protective layer 80. In addition, the thickness of the insulating film protective layer 60 is reduced, which reduces the maintenance frequency of the magnetron sputtering equipment and the probability of pinhole defects in the insulating film protective layer 60, thereby reducing the equipment maintenance cost and the grinding processing cost of the insulating film protective layer 60.

[0044] In one embodiment, in the high-resistance wear-resistant protective layer project P6, the gas introduced is nitrogen, or a mixed gas of nitrogen and oxygen accounting for no more than 50% of the total flow ratio, or a mixed gas of nitrogen and argon accounting for no more than 50% of the total flow ratio as the working gas, and a high-resistance wear-resistant protective layer 70 with a thickness between 10 and 1000nm, a resistivity of no less than 100Ω·m, and an atomic content percentage of nitrogen or the sum of the atomic content percentages of nitrogen and oxygen not less than 20% is deposited. If the atomic content percentage of nitrogen or the sum of the atomic content percentages of nitrogen and oxygen is less than 20%, there may be a lower limit value of the resistivity less than 100Ω·m, and the effect of the impedance between the electrode wire 51 and the low-resistance wear-resistant protective layer 80 being greater than tens of megohms cannot be achieved. The thickness of the high-resistance wear-resistant protective layer 70 can be as low as 10nm, and the resistivity can reach an effect of no less than 100Ω·m.

[0045] The heating substrate for the thin film thermal print head formed by the method of the present application has a high resistance wear-resistant protective layer 70 with a deposition thickness of 10 to 1000 nm and a resistivity of not less than 100 Ω·m between the low resistance wear-resistant protective layer 80 and the insulating film protective layer 60. Even if the insulating film protective layer 60 has defects such as pinholes, the impedance between the electrode wire 51 and the low resistance wear-resistant protective layer 80 will still be greater than tens of megohms. In this way, when the thermal print head is powered on, the potential on the low resistance wear-resistant protective layer 80 will be much lower than the printing voltage of the thermal print head, thereby achieving the effect of reducing the probability of electrochemical corrosion of the thin film thermal print head. In addition, the thickness of the insulating film protective layer 60 is between 500 and 6000 nm, which can not only reduce the thickness of the insulating film protective layer 60, but also avoid the problem of insufficient impedance between the electrode wire 51 and the low resistance wear-resistant protective layer 80. In addition, the thickness of the insulating film protective layer 60 is reduced, which reduces the maintenance frequency of the magnetron sputtering equipment and the probability of pinhole defects in the insulating film protective layer 60, thereby reducing the equipment maintenance cost and the grinding processing cost of the insulating film protective layer 60, which is conducive to large-scale production.

[0046] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for manufacturing a heating substrate for a thin film thermal print head, comprising: an insulating protective layer process: forming an insulating thin film protective layer at least partially on a surface of an insulating substrate provided with a heating resistor and an electrode wire; characterized in that: Also includes: High-resistance wear-resistant protective layer engineering: using a target material whose main component is carbon and whose additional component is silicon carbide, using a DC or AC magnetron sputtering device, introducing nitrogen, or a mixture of nitrogen and oxygen, or a mixture of nitrogen and argon as a working gas, to form a high-resistance wear-resistant protective layer with a thickness of 10 to 1000 nm and a resistivity of not less than 100Ω·m on the insulating film protective layer; Low resistance wear-resistant protective layer engineering: using a target material whose main component is carbon and whose additional component is silicon carbide, using DC or AC magnetron sputtering equipment, introducing argon as the working gas, a high resistance wear-resistant protective layer with a thickness of 1000 to 6000nm and a resistivity of 10 -3 Ω·m~10 -1 Ω·m low resistance wear-resistant protective layer; In the high-resistance and wear-resistant protective layer, the atomic content percentage of nitrogen or the sum of the atomic content percentages of nitrogen and oxygen is not less than 20%.

2. The method for manufacturing a heating substrate for a thin film thermal print head as claimed in claim 1, wherein in the high resistance and wear resistant protective layer process, in the mixed gas of nitrogen and oxygen, the oxygen accounts for no more than 50% of the total flow rate.

3. The method for manufacturing a heat generating substrate for a thin film thermal print head according to claim 1, wherein: In the high-resistance wear-resistant protective layer project, in the mixed gas of nitrogen and argon, the argon accounts for no more than 50% of the total flow rate.

4. The method for manufacturing a heat generating substrate for a thin film thermal print head according to claim 1, wherein: The thickness of the insulating film protection layer is 500-6000nm.

5. The method for manufacturing a heat generating substrate for a thin film thermal print head according to claim 1, wherein: After the low-resistance wear-resistant protective layer engineering, it also includes: Organic resin layer process: using a solder resist material with epoxy resin as the main component, at least in a set area on the insulating substrate, an organic resin layer is formed by a method of heating and curing after printing.

6. The method for manufacturing a heat generating substrate for a thin film thermal print head according to claim 1, wherein: Before the insulation protection layer engineering, it also includes: Glazing process: forming a glaze coating on one surface of the insulating substrate; Common electrode process: forming a common electrode on the surface of the insulating substrate and the glaze coating; Metal film process: forming a heating resistor layer on the insulating substrate and the glaze coating, and forming an electrode conductor layer on the heating resistor layer; Graphical engineering: using photolithography combined with etching to form the heating resistor layer and the electrode conductor layer into a plurality of heating resistors and electrode conductors.

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