A heating substrate for a thermal print head to prevent unexpected heating and a manufacturing method thereof

Abstract

The present application provides a heating substrate and manufacturing method for a thermal print head to prevent unexpected heating, which solves the technical problem of unexpected heating that may occur in the existing thermal print head in the power-on standby state; including: insulating protective layer engineering: the surface of the heating resistor and the electrode wire is provided on the insulating substrate, and the insulating protective layer is at least partially formed; also including: high-resistance wear-resistant protective layer engineering: using a target material with carbon as the main component and silicon carbide as an additive, using a DC or AC magnetron sputtering device, passing a mixed gas of nitrogen and argon as a working gas, and forming a high-resistance protective layer on the insulating protective layer; low-resistance wear-resistant protective layer engineering: using a target material with carbon as the main component and silicon carbide as an additive, using a DC or AC magnetron sputtering device, passing argon as a working gas, and forming a low-resistance protective layer on the high-resistance protective layer. The present application 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 heating substrate for a thermal print head that prevents unexpected heating and a manufacturing method thereof. Background Art

[0002] As is known to all, in general, the heating substrate of a thermal print head includes the following structure: using glaze slurry, a bottom glaze layer is formed on the insulating substrate in whole or in part by printing and sintering; electrode wires and a heating resistor powered by the electrode wires are formed on the bottom glaze layer and the insulating substrate, wherein the electrode wires include a common electrode and an individual electrode; an insulating protective layer is formed on the heating resistor and at least a part of the electrode wires connected to the heating resistor by a thick film method or a method using vacuum film forming technology such as sputtering and CVD; in order to reduce the risk of static electricity generated by the thermal print head during the printing process to damage the print head, a vacuum film forming technology such as sputtering and CVD is also used to form a wear-resistant protective layer with a conductive effect in a set area on the insulating protective layer; for example, a protective layer containing a diamond-like carbon (DLC) structure is used, and its resistivity is between 10 -3 Ω·m~10 -1 It is between Ω·m and has good wear resistance, and is usually used as a wear-resistant protective layer for thermal print heads.

[0003] The thermal print head including the above structure will inevitably have pinhole defects due to the insulating protective layer formed by thick film method or vacuum film forming technology. In this way, the insulation impedance between the wear-resistant protective layer and the electrode wire may be too low, for example, the insulation impedance between the wear-resistant protective layer and the electrode wire is hundreds of kiloohms or as low as tens of kiloohms. When the thermal print head is powered on, the wear-resistant protective layer will have a potential close to that of the electrode wire, which may easily cause the wear-resistant protective layer of the thermal print head to form a conductive path with the low-potential printing medium or conductive rubber roller in a humid environment, and the thermal print head may have unexpected heating problems when powered on and in standby mode.

[0004] In order to solve this problem, in the prior art, pinhole defects can be reduced by forming a laminated film on the insulating protective layer and adding a grinding process in the middle of the laminate, but this will result in reduced production efficiency and increased production costs. Summary of the invention

[0005] 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 thermal print head to prevent unexpected heating in a power-on standby state, including: an insulating protective layer process: forming an insulating protective layer at least partially on a surface of an insulating substrate on which a heating resistor and an electrode wire are provided; and also including:

[0006] High resistance and wear-resistant protective layer engineering: using a target material with carbon as the main component and silicon carbide as an additive, using DC or AC magnetron sputtering equipment, introducing a mixed gas of nitrogen and argon as the working gas, to form a high resistance protective layer on the insulating protective layer;

[0007] Low-resistance wear-resistant protective layer project: using a target material with carbon as the main component and silicon carbide as an added component, using DC or AC magnetron sputtering equipment, introducing argon as the working gas, to form a low-resistance protective layer on the high-resistance protective layer.

[0008] Preferably, in the high-resistance wear-resistant protective layer project, the total flow rate ratio of argon gas to the mixed gas is 0% to 50%.

[0009] Preferably, the resistivity ratio of the high-resistance protective layer to the low-resistance protective layer is not less than 1000.

[0010] Preferably, the resistivity of the high resistance protection layer is not less than 100Ω·m.

[0011] Preferably, the thickness of the high resistance protection layer is 10 nm to 1000 nm.

[0012] Preferably, the resistivity of the low resistance protective layer is 10 -3 Ω·m~10 -1 Ω·m.

[0013] Preferably, after the low-resistance wear-resistant protective layer engineering, it also includes:

[0014] 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.

[0015] Preferably, before the insulating protective layer engineering, it also includes:

[0016] Glazing project: forming a glaze coating on one side surface of the insulating substrate;

[0017] Common electrode engineering: forming a common electrode on the surface of the insulating substrate and the glaze coating;

[0018] 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;

[0019] 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.

[0020] The present invention also provides a heating substrate for a thermal print head to prevent 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 powered by the common electrode and the individual electrodes; an insulating protective layer covering the heating resistor and at least a portion of the electrode wire connected to the heating resistor; a high-resistance protective layer covering at least a portion of the insulating protective layer; and a low-resistance protective layer covering the high-resistance protective layer.

[0021] The resistivity ratio of the high-resistance protective layer to the low-resistance protective layer is not less than 1000.

[0022] Preferably, the high-resistance protection layer contains at least one of carbon nitride and silicon nitride in addition to the material of the low-resistance protection layer.

[0023] The beneficial effect of the present invention is that, on the insulating protective layer, under the condition of using the same target material with carbon as the main component and silicon carbide as the additive component, a DC or AC magnetron sputtering device is used to pass nitrogen and a mixed gas of argon accounting for 0% to 50% of the total flow rate as the working gas to form a high-resistance protective layer, and argon is passed as the working gas to form a low-resistance protective layer. First, the composition of the materials of the high-resistance protective layer and the low-resistance protective layer is basically the same, so the bonding force is better. Secondly, the two processes are different, resulting in different final properties. The resistivity of the high-resistance protective layer is more than 1000 times higher than that of the low-resistance protective layer. Therefore, even if the insulating protective layer has defects such as pinholes, the impedance between the electrode wire and the low-resistance protective layer will still be greater than tens of megohms, and the low-resistance protective layer no longer has a potential close to the working potential of the thermal print head. Therefore, it will not form a conductive path with the low-potential printing medium or conductive rubber roller in a humid environment, fundamentally solving the problem of unexpected heating of the thermal print head in the standby state. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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.

[0025] Figure 1 is a simplified manufacturing flow chart of the present invention;

[0026] Figure 2 is a schematic cross-sectional view of the heating substrate of the present invention;

[0027] Figure 3 It is a plan view of the heating substrate of the present invention.

[0028] Explanation of symbols in the figure:

[0029] 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 protective layer; 70. High-resistance protective layer; 80. Low-resistance protective layer; 90. Organic resin layer. DETAILED DESCRIPTION

[0030] 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.

[0031] The heating substrate 01 for a thermal print head and the manufacturing method provided in the embodiment of the present application are now described.

[0032] See also Figure 1 and Figure 2 The manufacturing method of the heat-generating substrate 01 for a thermal print head for preventing unexpected heating of this embodiment includes:

[0033] Glazing process P1: forming a glaze coating 20 on one side surface of the insulating substrate 10; specifically, on the parallel plate-shaped insulating substrate 10 whose main component is aluminum oxide, a glass glaze slurry is printed and sintered to partially form a heat storage glaze coating 20 on one surface of the insulating substrate 10;

[0034] Common electrode process P2: using thick film silver paste, adopting printing and sintering method to form common electrode 30;

[0035] Metal film engineering P3: Using a metal ceramic target, such as a composite material target formed of tantalum and silicon dioxide, a heating resistor layer 40 is formed on the insulating substrate 10 and the glaze coating 20 by magnetron sputtering, and using an aluminum target, an electrode conductor layer 50 is formed on the heating resistor layer 40 by magnetron sputtering;

[0036] Graphics process P4: A photolithography plate for photolithography is designed and manufactured in advance according to necessary information such as printing resolution, and the photolithography is combined with etching to form a plurality of heating resistors 41 and electrode conductors 51 from the heating resistor layer 40 and the electrode conductor layer 50;

[0037] Insulation protection layer process P5: using silicon oxynitride or Sialon ceramic composite target material, using argon as the plasma generating gas, and adopting the radio frequency magnetron sputtering method, the surface of the insulating substrate 10 provided with the heating resistor 41 and the electrode wire 51 is provided with an insulation protection layer 60 at least partially;

[0038] High resistance and wear-resistant protective layer engineering P6: using a target material with carbon as the main component and silicon carbide as an additive, using a DC or AC magnetron sputtering device, introducing a mixed gas of nitrogen and argon accounting for 0% to 50% of the total flow rate as the working gas, to form a high resistance protective layer 70 on the insulating protective layer 60;

[0039] Low-resistance wear-resistant protective layer project P7: using a target material with carbon as the main component and silicon carbide as an additive, using a DC or AC magnetron sputtering device, introducing argon as a working gas, to form a low-resistance protective layer 80 on the high-resistance protective layer;

[0040] Organic resin layer process P8: Using a solder resist material having epoxy resin as a main component, an organic resin layer 90 is formed at least in a set area on the insulating substrate 10 by a method of printing and then heating and curing.

[0041] In this way, the resistivity of the high-resistance protective layer 70 is more than 1000 times higher than that of the low-resistance protective layer 80. Thus, even if there are defects such as pinholes in the insulating protective layer 60, the impedance between the electrode wire 51 and the low-resistance protective layer 80 will still be greater than tens of megohms. The low-resistance protective layer 80 no longer has a potential close to the working potential of the thermal print head, so it will not form a conductive path with the low-potential printing medium or the conductive rubber roller in a humid environment, fundamentally solving the problem of unexpected heating of the thermal print head in the standby state.

[0042] Furthermore, in one embodiment, the high resistance and wear resistant protective layer engineering P6 specifically includes:

[0043] The conductive target material with carbon as the main component and silicon carbide as the additive component is bonded to the copper cathode back plate with indium as the welding material and placed in the vacuum chamber of the magnetron sputtering machine. The copper cathode is connected to a DC power supply or an AC power supply. Under vacuum conditions, a certain flow of nitrogen and argon is introduced into the vacuum chamber. The area of ​​the target material is used as a reference, and the pressure is 3w / cm 2The cathode is energized with a power density of 1000 Å, and the nitrogen and argon gases are ionized by the power, forming a plasma containing nitrogen ions, argon ions, and electrons. Under the action of the electric field, the argon ions and nitrogen ions bombard the target material, and cause the carbon and silicon elements in the target material to separate from the target material in the state of atoms and enter the plasma, and then collide with the ions or electrons in the plasma to form charged particles, which further combine with the nitrogen ions to form more carbon nitrides and silicon nitrides, and adhere to the surface of the insulating protective layer 60 of the insulating substrate 10. Since argon ions usually have a larger mass-to-charge ratio than nitrogen ions, argon ions have a relatively higher atomic yield when bombarding the target material. The percentage of argon gas flow is controlled between 0% and 50%, for example, 20 sccm of argon gas and 60 sccm of nitrogen gas, so that the charged particles have more opportunities to combine with nitrogen ions to form carbon nitrides and silicon nitrides. The power density on the target material is controlled at a lower level, which is also to allow the generated charged particles to have enough opportunities to combine to form nitrides. As more carbon and silicon are combined with nitrogen to become non-conductive nitrides, a high-resistance protection layer 70 with a resistivity of not less than 100 Ω·m is eventually formed on the surface of the insulating protection layer 60 .

[0044] The thickness of the high-resistance protection layer 70 can be controlled in combination with the resistivity of the high-resistance protection layer 70. For example, when the resistivity is 100Ω·m and the thickness is 100nm, the sheet resistance of the high-resistance protection layer 70 is 1000MΩ. Moreover, the film whose main component is carbon has good diffraction performance, so it can produce a good shielding effect on the pinhole defects formed by the insulating protection layer 60.

[0045] Furthermore, in one embodiment, the low-resistance wear-resistant protective layer project P7 specifically includes:

[0046] The same target material and equipment as the high resistance wear-resistant protective layer project P6 are used, and argon is used as the working gas at 6w / cm 2 The cathode is energized with a power density of 1000 Ω. Since argon is an inert gas, the carbon and silicon in the target material will not combine with the argon ions to form new compounds. Therefore, a low-resistance protective layer 80 with a composition similar to that of the target material will be formed on the surface of the same area as the high-resistance protective layer 70.

[0047] Since the pinhole defects of the insulating protective layer 60 have been shielded by the high-resistance protective layer 70, the low-resistance protective layer 80 has almost no chance to contact the electrode wire 51. Therefore, the impedance between the electrode wire 51 and the low-resistance protective layer 80 is similar to or the same as the square resistance of the high-resistance protective layer 70 in most cases.

[0048] In the method of the present invention, when the target material with carbon as the main component and silicon carbide as the additive component is used, a DC or AC magnetron sputtering device is used to introduce a mixed gas of nitrogen and argon accounting for 0% to 50% of the total flow rate as a working gas to form a high-resistance protective layer 70, and argon is introduced as a working gas to form a low-resistance protective layer 80. First, the composition of the materials of the high-resistance protective layer 70 and the low-resistance protective layer 80 is basically the same, so the bonding force is better. Secondly, the two processes are different, resulting in different final properties. The resistivity of the high-resistance protective layer 70 is more than 1000 times higher than that of the low-resistance protective layer 80. Therefore, even if the insulating protective layer 60 has defects such as pinholes, the impedance between the electrode wire 51 and the low-resistance protective layer 80 will still be greater than tens of megohms, and the low-resistance protective layer 80 no longer has a potential close to the working potential of the thermal print head. Therefore, it will not form a conductive path with the low-potential printing medium or the conductive rubber roller in a humid environment, fundamentally solving the problem of unexpected heating of the thermal print head in the standby state.

[0049] The present invention also provides a heating substrate 01 for a thermal print head to prevent unexpected heating. Figure 2 , Figure 3 , which is a structural schematic diagram of a heating substrate for a thermal print head to prevent unexpected heating, the heating substrate 01 for a thermal print head to prevent unexpected heating includes an insulating substrate 10; a glaze coating 20 formed at least partially on the surface of the insulating substrate 10; an electrode wire 51 formed on the surface of the insulating substrate 10 and the glaze coating 20, the electrode wire 51 including a common electrode and an individual electrode; a heating resistor 40 powered by the common electrode and the individual electrode; an insulating protective layer 60 covering the heating resistor 40 and at least a portion of the electrode wire 51 connected to the heating resistor 40; a high-resistance protective layer 70 covering at least a portion of the insulating protective layer 60; and a low-resistance protective layer 80 covering the high-resistance protective layer 70.

[0050] The resistivity ratio of the high resistance protection layer 70 to the low resistance protection layer 80 is not less than 1000.

[0051] In one embodiment, the high resistance protection layer 70 contains at least one of carbon nitride and silicon nitride in addition to the material of the low resistance protection layer 80. The composition of the two materials is basically the same, and the bonding force is better.

[0052] Furthermore, the resistivity of the high resistance protection layer 70 is not less than 100 Ω·m.

[0053] Furthermore, the thickness of the high resistance protection layer 70 is 10 nm to 1000 nm.

[0054] More preferably, the resistivity of the low resistance protection layer 80 is 10 -3 Ω·m~10 -1 Ω·m.

[0055] In one embodiment, the heat generating substrate 01 for a thermal print head for preventing unexpected heating further includes an organic resin layer 90 covering at least a set area on the insulating substrate 10 .

[0056] The heating substrate for the thermal print head formed according to the method of the present invention will not have the problem of abnormal heating even when it is in the power-on standby state in a high temperature and humid environment. The resistivity of the high-resistance protective layer 70 is not less than 100Ω·m, and is more than 1000 times higher than the resistivity of the low-resistance protective layer 80. Even if there are pinhole defects in the insulating protective layer 60, the insulation impedance between the low-resistance protective layer 80 and the electrode wire 51 will be greater than tens of megohms. When the thermal print head is powered on and on standby, the potential on the low-resistance protective layer 80 will be much lower than the potential of the electrode wire 51, and the risk of unexpected heating of the thermal print head will be greatly reduced. In addition, the high-resistance protective layer 70 and the low-resistance protective layer 80 are formed using the same target material, which means that the high-resistance protective layer 70 and the low-resistance protective layer 80 can be formed using the same equipment, so there will be no problem of significantly reduced production efficiency.

[0057] 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 thermal print head to prevent unexpected heating, comprising: an insulating protective layer process: forming an insulating protective layer at least partially on a surface of an insulating substrate on which a heating resistor and an electrode wire are provided; characterized in that: Also includes: High resistance and wear-resistant protective layer engineering: using a target material with carbon as the main component and silicon carbide as an additive, using a DC or AC magnetron sputtering device, introducing a mixed gas of nitrogen and argon as the working gas, to form a high resistance protective layer on the insulating protective layer; Low-resistance wear-resistant protective layer engineering: using a target material with carbon as the main component and silicon carbide as an additive, using DC or AC magnetron sputtering equipment, introducing argon as the working gas, to form a low-resistance protective layer on the high-resistance protective layer; The ratio of the resistivity of the high-resistance protective layer to the resistivity of the low-resistance protective layer is not less than 1000; The resistivity of the high resistance protective layer is not less than 100Ω•m; The resistivity of the low resistance protective layer is 10 -3 Ω•m~10 -1 Ω•m; The high-resistance protection layer contains at least one of carbon nitride and silicon nitride in addition to the material of the low-resistance protection layer.

2. The method for manufacturing a heat-generating substrate for a thermal print head for preventing unexpected heating according to claim 1, wherein: In the high-resistance wear-resistant protective layer project, the argon gas accounts for 0% to 50% of the total flow rate of the mixed gas.

3. The method for manufacturing a heat-generating substrate for a thermal print head for preventing unexpected heating according to claim 1, wherein: The thickness of the high resistance protection layer is 10nm-1000nm.

4. The method for manufacturing a heat-generating substrate for a thermal print head for preventing unexpected heating 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.

5. The method for manufacturing a heat-generating substrate for a thermal print head for preventing unexpected heating according to claim 1, wherein: Before the insulation protection layer engineering, it also includes: Glazing process: forming a glaze coating on one side 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.

6. A heating substrate for a thermal print head that prevents unexpected heating, manufactured by the manufacturing method according to any one of claims 1 to 5, characterized in that: The invention comprises an insulating substrate; a glaze coating formed on at least part of the surface of the insulating substrate; a plurality of heating resistors formed on the surfaces of the insulating substrate and the glaze coating; electrode wires formed on the heating resistors; an insulating protective layer covering the heating resistors and at least part of the electrode wires connected to the heating resistors; a high-resistance protective layer covering at least part of the insulating protective layer; a low-resistance protective layer covering the high-resistance protective layer; the electrode wires comprising a common electrode and an individual electrode; the heating resistors are powered by the common electrode and the individual electrode; Wherein, the resistivity ratio of the high-resistance protective layer to the low-resistance protective layer is not less than 1000.

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