Thin film thermal print head and manufacturing method thereof

Abstract

The present invention relates to the technical field of thermal print head manufacturing, and more specifically, to a thin-film thermal print head and a method for manufacturing the same, which significantly improves the quality and service life of the print head by utilizing corrosion-resistant, high-temperature-resistant, and low-stress wire electrodes. The invention is characterized in that the electrode wire at least within 300 μm of a heating resistor is an aluminum-based alloy electrode wire, and the aluminum-based alloy electrode wire contains metal aluminum, metal copper, metal chromium, and metal zirconium, wherein metal copper accounts for less than 5% of the total mass of the aluminum-based alloy electrode wire, metal chromium and metal zirconium account for less than 1% of the total mass of the aluminum-based alloy electrode wire, and the remainder is metal aluminum. Compared with the prior art, the resulting wire electrode has better adhesion, heat dissipation, conductivity, and low thermal stress, and can significantly improve the service life and quality of the product.

Description

Technical field:

[0001] The present invention relates to the technical field of thermal print head manufacturing, and in particular to a thin film thermal print head and a manufacturing method thereof, which significantly improves the quality and service life of the print head by means of corrosion-resistant, high-temperature-resistant, low-stress wire electrodes. Background technology:

[0002] As is well known, a thin film thermal print head is provided with a substrate made of insulating material. The electrical part of the thermal print head is composed of a wire electrode, a heating resistor, a control IC, etc. on a ceramic substrate. The electrical part is adhered as a whole to a heat dissipation base. A heat storage layer is made on the substrate, which is the base glaze. Then, a heating resistor is formed on the surface of the substrate and the heat storage layer. A wire electrode electrically connected to the heating resistor is formed above or below the heating resistor. The wire electrode is divided into individual electrodes and common electrodes. Among them, one end of the individual electrode is connected to the heating resistor along the sub-printing direction, and the other end is connected to the control IC. One end of the common electrode is connected to the heating resistor belt along the sub-printing direction, and the other end is connected to the power supply.

[0003] Metals such as Au, Ag, and Cu offer excellent conductivity for conductive electrodes. However, Au is expensive and complex to manufacture, while Ag exhibits poor thermal stability. Cu exhibits poor adhesion to the substrate protective film and poor solderability to ICs. Therefore, thin-film printhead electrodes are typically made of pure aluminum, typically around 1 μm thick. Aluminum is an excellent conductor of electricity, with a resistivity of less than 2.8 x 10-8 Ω·m. It is also a good thermal conductor, with a thermal conductivity exceeding 200 W / mK, facilitating heat dissipation. However, aluminum has a high coefficient of thermal expansion, approximately 23 ppm / °C, compared to 4-9 ppm / °C for other components in thermal printheads. This results in significant thermal stress when using Al for electrode conductors. Furthermore, aluminum has a temperature resistance of only around 600°C. When operating in high-temperature and high-humidity environments, Al electrode conductors are susceptible to corrosion and thermomigration. This occurs when metal atoms in the alloy undergo directional migration under the influence of a temperature gradient. These atoms then aggregate at either the hot or cold end, leading to defects such as voids and cracks. These shortcomings may affect the lifespan of thin-film printheads under high load and high temperature conditions. Therefore, there is an urgent need for a thermal printing electrode lead that has strong adhesion to the substrate protective layer, meets the requirements of high conductivity and good heat dissipation during thermal printing, and exhibits stable resistance to thermal migration, in order to improve the quality of thermal printhead products.

[0004] Existing thermal printhead products, such as the technical proposal described in patent document JP2022078438, mention that the electrode wire is composed of Cu, Cu alloys, Al, Al alloys, Au, Ag, Ni, W, etc., with a thickness of 800nm. However, no further investigation is conducted on the bonding strength of the electrode wire material with the substrate and protective layer, heat dissipation, thermal migration resistance, or process difficulty.

[0005] To improve adhesion between the Al Com and the feed electrode, JP2003154967 proposes a two-layer structure using one of the following metals: Ti, Cr, Nb, Ta, W, or Zr for the adhesion layer and Au or an Au alloy for the corrosion-resistant layer. However, Au is expensive, increasing product costs.

[0006] Patent document US5077563A mentions that the electrical contact portion of each recording electrode of the print head has a thickness of at least one micron and is basically composed of a conductive material for resisting oxidation and degradation. The conductive material is selected from nitrides, and each nitride contains at least one element selected from chromium, titanium, tantalum, zirconium and niobium.

[0007] Patent document 202211551818.3 mentions that the electrode layer includes a first electrode layer and a second electrode layer, with the first electrode layer located on the side of the second electrode layer closer to the insulating substrate. The first electrode layer is made of at least one of aluminum, tungsten, titanium, molybdenum, and silver, or an alloy thereof; the second electrode layer is made of aluminum. Using two layers, one of which is made of materials such as tungsten and titanium to form a corrosion-resistant electrode, is complex and costly compared to pure aluminum or aluminum-based electrodes. Summary of the invention:

[0008] In response to the shortcomings and deficiencies in the prior art, the present invention proposes a thin-film thermal print head and a method for manufacturing the same, which have reasonable cost and simple process, can significantly improve the corrosion resistance and high-temperature resistance of aluminum-based wire electrodes, and reduce the stress of aluminum-based wire electrodes, thereby providing better product quality.

[0009] The present invention is achieved by the following measures:

[0010] A thin film thermal print head comprises an insulating substrate, a base glaze layer is provided on the surface of the insulating substrate, a heating resistor and an electrode wire are provided on the base glaze layer, and the characteristic is that the electrode wire at least within 300 μm from the heating resistor is an aluminum-based alloy electrode wire, and the aluminum-based alloy electrode wire contains metal aluminum, metal copper, metal chromium, and metal zirconium, wherein metal copper accounts for less than 5% of the total mass of the aluminum-based alloy electrode wire, metal chromium and metal zirconium account for less than 1% of the total mass of the aluminum-based alloy electrode wire, and the rest is metal aluminum.

[0011] The ratio of chromium (Cr) to the total mass percentage of chromium (Cr) and zirconium (Zr) in the aluminum-based alloy electrode wire of the present invention is between 35% and 65%. As a result, the aluminum-based alloy electrode wire exhibits a positive interaction while maintaining a low expansion coefficient, forming a network-like structure of alloy elements. This allows for a multi-component Al / Cu alloy electrode with uniform texture and stable component transfer, thereby effectively inhibiting the migration of Al and Cu atoms and improving the poor bonding strength of the Cu component with the base and protective film.

[0012] The electrode conductors described in the present invention can be arranged in two ways according to needs. If the thermal / electrical / chemical stability requirements are high, the electrodes 1 and 2 can be made of aluminum-based alloys. If the conductive weldability requirements are high, a two-section overlap structure can be adopted, in which the electrode conductors within 300um from the heating resistor adopt the aluminum-based alloy electrode conductors as described above, and the electrode conductors greater than 300μm from the heating resistor adopt pure aluminum conductors. The aluminum-based alloy electrode conductors and the pure aluminum conductors are overlapped to form an electrical connection. The thickness of the electrode conductors is 1±0.5μm, and the overlap area is at least 20um.

[0013] The upper surface of the electrode wire of the present invention is also provided with a protective layer, which includes an insulating layer, which can prevent the electrode and the heating resistor from being corroded by external ions, water vapor, etc. A wear-resistant layer can be further formed on the insulating layer according to wear resistance requirements. The wear-resistant layer is made of SIC film. SIC has high hardness and can provide good scratch resistance and wear resistance.

[0014] The present invention also provides a method for manufacturing the thin film thermal print head as described above, comprising first forming an underglaze layer on the surface of an insulating substrate, and then forming a heating resistor and an electrode wire on the underglaze layer on the insulating substrate, wherein the electrode wire comprises an aluminum-based alloy electrode wire, and the formation of the aluminum-based alloy electrode wire comprises the following steps:

[0015] Step 1: Prepare Al / Cu alloy target material using a vacuum induction melting furnace and a graphite crucible. The Al matrix uses 99.99% aluminum particles, and the Cu, Cr, and Zr components use high-purity particles, where Cu ≥ 99.99%, Cr ≥ 99.95%, and Zr ≥ 99.95%. The raw materials remain molten in the melting furnace for a long time. The liquid is in a high-temperature, high-vacuum environment. The temperature, vacuum degree, and heating power are controlled. Inert gas (such as Ar) is filled in as needed and a deoxidizer is added to prevent oxidation and boiling.

[0016] Step 2: On the surface of the insulating substrate where the heating resistor has been made, use the alloy target material obtained in step 1 to plate an alloy film by magnetron sputtering with a thickness of 1±0.5um. In order to make the alloy more evenly distributed, -4Solution treatment is carried out below 550℃ in a Pa vacuum environment to improve corrosion resistance. In order to obtain better conductivity, after solution treatment, annealing treatment is carried out at 150-200℃ to precipitate a very small amount of solid solution components to form a dispersed distribution, reduce the resistivity of the alloy, and improve conductivity;

[0017] Step 3: Electrode patterning: Apply positive photoresist and perform photolithography to retain at least the high-temperature area within a distance of 0 to 300 μm from the heating resistor. Then perform imaging. After imaging, use a wet etching process to remove the alloy without photoresist protection to form an electrode pattern.

[0018] In the method for manufacturing a thin film thermal print head described in the present invention, when the electrode wire that is more than 300 μm away from the heating resistor is an aluminum wire, in step 3, only the positive photoresist within a distance of 0-300 μm from the heating resistor is retained, thereby forming an aluminum-based alloy electrode wire only within a range of 0-300 μm from the heating resistor. Thereafter, an Al target is used to sputter an Al thin film above the aluminum-based alloy electrode wire, and electrode patterning is performed to obtain an Al electrode wire that is more than 300 μm away from the heating resistor and overlaps the aluminum-based alloy electrode wire by at least 20 μm.

[0019] The method for manufacturing a thin-film thermal print head of the present invention further includes forming an insulating layer on the wire electrode to prevent corrosion of the electrode and the heating resistor by external ions, water vapor, etc., and forming a wear-resistant layer on the insulating layer according to wear resistance requirements. The wear-resistant layer is prepared using a thin film SIC. The SIC has high hardness and can provide excellent scratch resistance and wear resistance.

[0020] Compared with the prior art, the present invention sets an aluminum-based alloy electrode wire at least in the high-temperature area (within 300 μm from the heating resistor), which can significantly inhibit the diffusion of Al atoms in the electrode wire under the action of thermal migration, thereby making the electrode more stable. On the basis of adding Cu, Cr and Zr are further added, and the total content of Cr and Zr is controlled below 1% (too high a content will affect the conductivity of the electrode due to the high resistivity of Cr and Zr). The wire electrode shows a positive interaction while maintaining a low expansion coefficient, making the alloy texture uniform, thereby effectively inhibiting the migration of Al and Cu atoms, and improving the problem of poor bonding between the traditional Cu component and the substrate and protective film. It can also weaken the preferential sputtering caused by the difference in injection effect during magnetron sputtering, so that the target material is sputtered more evenly and the generated film quality is also more uniform. The obtained wire electrode has better adhesion, heat dissipation, conductivity and low thermal stress, which can significantly improve the service life and quality of the product. Description of the drawings:

[0021] Attachment Figure 1It is a schematic diagram of the cross-sectional structure of the thin film thermal print head of the present invention.

[0022] Attachment Figure 2 It is a structural schematic diagram of the heating resistor and electrode wire in the present invention.

[0023] Attachment Figure 3 It is a schematic diagram of two-segment electrodes in the present invention.

[0024] Attachment Figure 4 It is a flow chart of the method for manufacturing the thin film thermal print head in the present invention.

[0025] Attachment Figure 5 This is a comparison of the leakage current change curves of Al electrode and Al-Cu alloy electrode over time.

[0026] Attachment Figure 6 This is a schematic diagram comparing the morphologies of aluminum-copper alloys after adding Cr and Zr.

[0027] Attachment Figure 7 Schematic diagram of adhesion test.

[0028] Attachment Figure 8 Comparison histogram of Cr sputtering rate in alloys with and without Zr.

[0029] Reference numerals: ceramic substrate 1 , heat storage layer 2 , heating resistor 3 , electrode 4 , electrode 1 4 - 1 , electrode 2 4 - 2 , individual electrode 4 a , common electrode 4 b , protective film 5 . Specific implementation method:

[0030] Example 1

[0031] This example provides a thin film thermal print head, as shown in the attached Figure 1 As shown, it includes a ceramic substrate 1 with a heat storage layer 2, i.e., a bottom glaze, and a heating resistor is formed on the ceramic substrate 1 by a thin film patterning process. The thin film process is generally implemented by PVD, CVD, ion plating, evaporation, electroplating, chemical plating and other processes. The patterning process adopts processes such as coating photoresist, photolithography, and etching. Etching can adopt RIE dry process or wet process. The heating resistor 3 is composed of Ta-based materials, generally TaSiO2. A similar thin film patterning process is adopted to form a wire electrode. The wire electrode includes an individual electrode 4a and a common electrode 4b. One end of the individual electrode 4a is connected to the heating resistor 3 and the other end is connected to the IC. One end of the common electrode 4b is connected to the heating resistor 3 and the other end is connected to the positive pole of the power supply.

[0032] In this example, the wire electrode is made of a material mainly composed of Al, and other metals are added to Al to form an alloy. Specifically, in this example, Cu is added to aluminum. Cu is a good conductor and is widely used. Cu has good conductivity and a resistivity of 1.7x10E-8Ω·m. Cu has a higher temperature resistance than aluminum, about 1000℃. Cu also has a relatively high thermal conductivity of about 400W / mK. The thermal expansion coefficient of Cu is low, about 16.6ppm / ℃. The amount of Cu added accounts for less than 5% of the total mass of the wire electrode. By adding Cu, Cu is segregated at the grain boundaries of Al atoms, making the Cu-Al bond at the grain boundaries much stronger than the Cu-Cu and Al-Al bonds. This means that Cu strengthens the grain boundaries of Al atoms, thereby inhibiting the grain boundary diffusion of Al atoms, making the electrode more stable. Figure 5 ,It can be seen that compared with the aluminum wire electrode, the aluminum-copper alloy wire electrode has a more stable performance;

[0033] However, aluminum-copper alloys still have the problem of atomic diffusion due to the thermal migration effect. In this example, Cr and Zr are further added on top of Cu. The total content of Cr and Zr is controlled to be less than 1% of the total mass of the electrode wire. This is because when the Cr or Zr content exceeds 1%, the resistivity of the electrode wire increases, affecting the conductivity of the electrode wire.

[0034] Since the electrode wires in this example are used in thin-film thermal print heads, if the thermal expansion coefficient of the electrode wires differs too much from that of other accessories, it will cause large thermal stress, which will affect the service life of the product during use. In order to solve this problem, the Cr addition amount is set in this example to account for 35-65% of the total added mass of Cr and Zr. This is because the thermal expansion coefficient of chromium Cr is 6.2ppm / ℃ and the thermal expansion coefficient of zirconium Zr is 9.6ppm / ℃, which are much smaller than the thermal expansion coefficients of Cu and Al, which can significantly reduce thermal stress. In addition, adding Cr and Zr to the Al-Cu alloy can make the alloy show a positive interaction, so that the alloy elements become a network structure. Figure 6 , a multi-element Al-based alloy electrode with uniform texture can be obtained, thereby effectively inhibiting the migration of Al and Cu atoms. At the same time, the addition of Cr and Zr can also weaken the preferential sputtering caused by the difference in injection effect during magnetron sputtering, making the target material more uniformly sputtered, such as Figure 8 The resulting film quality is also more uniform. Doping only one of Cr or Zr cannot achieve the effect of doping two metals at the same time.

[0035] Adding Cr and Zr can also improve the poor bonding strength between traditional aluminum-copper alloy and substrate (heat storage layer) and protective film (SIALON). Figure 7 As shown, Figure 7 It is considered that the main components of the heat storage layer and the protective layer are both SiO2.

[0036] In this example, the wire electrode adopts an alloy with Al as the main component. In addition to the above advantages, it can also simplify the process. The etching process can basically maintain the same process as pure aluminum. The bonding between the electrode and the upper and lower layers and the IC solderability substrate can be consistent with pure aluminum. Specifically, it mainly includes the following steps:

[0037] Al / Cu alloy targets are made using a vacuum induction melting furnace and a graphite crucible. The Al matrix is ​​made of 99.99% aluminum particles, and the Cu, Cr, and Zr components are high-purity particles (Cu ≥ 99.99%, Cr ≥ 99.95%, Zr ≥ 99.95%). The raw materials remain molten in the melting furnace for a long time, and the liquid is in a high-temperature, high-vacuum environment. The temperature, vacuum, and heating power need to be controlled at all times. Inert gas (such as Ar) can also be filled and a deoxidizer can be added to prevent oxidation and boiling.

[0038] On the surface of the substrate where the heating resistor and the heat storage layer have been prepared, the alloy target is used to plate an alloy film of about 1um by magnetron sputtering. Before the electrode is patterned, in order to make the alloy more evenly distributed, -4 Under a Pa vacuum environment, solution treatment is performed below 550°C to improve corrosion resistance. In order to obtain better conductivity, after solution treatment, annealing is performed at 150-200°C to allow a very small amount of solid solution components to precipitate and form a dispersed distribution, which can reduce the resistivity of the alloy and improve conductivity. After heat treatment, weak bonds, vacancies, and lattice defects are reduced, making the resistivity of the alloy closer to that of Al / Cu aluminum alloy;

[0039] Then apply positive photoresist, perform photolithography, and patterning. After patterning, use a wet etching process such as mixed acid to remove the alloy without photoresist protection to form an electrode pattern. In this example, no distinction is made between electrode 1 and electrode 2, that is, there are only alloy electrodes, so all electrodes are retained during the patterning process, including the area near R and away from R.

[0040] In order to determine the film quality, XRD detection, scratch adhesion detection, four-probe square resistance detection, laser stress testing and other means can be used to characterize and inspect the film quality.

[0041] After the film quality inspection is passed, an insulating layer is formed on the electrode. The insulating layer is made of SIALON film. SIALON has excellent insulation performance and can prevent external ions, water vapor, etc. from corroding the electrodes and heating resistors. According to the need for wear resistance, a wear-resistant layer is formed on the insulating layer. The wear-resistant layer is made of SIC film. SIC has high hardness and can play a good role in scratch resistance and wear resistance.

[0042] Example 2:

[0043] This example provides a thin film thermal print head, including a ceramic substrate with a heat storage layer, i.e., a base glaze. A heating resistor is formed on the substrate using a thin film patterning process. The thin film process is generally implemented using processes such as PVD, CVD, ion plating, evaporation, electroplating, and chemical plating. The patterning process uses processes such as coating photoresist, photolithography, and etching. Etching can be performed using a dry RIE process or a wet process. The heating resistor is made of a Ta-based material, generally TaSiO2. A similar thin film patterning process is used to form individual electrodes 4a and a common electrode 4b in a high-temperature working area near the heating resistor (0-300 μm). One end of the individual electrode 4a is connected to the heating resistor and the other end is connected to an IC. One end of the common electrode 4b is connected to the heating resistor and the other end is connected to the positive pole of a power supply. The electrode near the heating resistor is made of a material mainly composed of Al. Other metals are added to Al to form an alloy. In this example, metal Cu is added. Cu is a good conductor and is widely used. Cu has good conductivity and a resistivity of 1.7x 10E-8Ω·m; Cu has a higher temperature resistance than aluminum, about 1000℃; Cu has a relatively high thermal conductivity, about 400W / mK, and a low thermal expansion coefficient, about 16.6ppm / ℃. The Cu content is controlled below 5%. Adding Cu to Al and utilizing the segregation of Cu at the grain boundaries of Al atoms makes the Cu-Al bond at the grain boundaries much stronger than the Cu-Cu and Al-Al bonds. This means that Cu strengthens the grain boundaries of Al atoms, thereby inhibiting the grain boundary diffusion of Al atoms, making the electrode more stable. However, there is still the problem of atomic diffusion of Cu. To solve the problem, Cr and Zr are further added on the basis of Cu, and the total content of Cr and Zr is controlled below 1% (too high a content will affect the conductivity of the electrode due to the high resistivity of Cr and Zr). Cr accounts for 40-60% of the total mass of Cr and Zr. The thermal expansion coefficient of chromium Cr is 6.2ppm / ℃, and the thermal expansion coefficient of zirconium Zr is 9.6ppm / ℃, which is much smaller than the thermal expansion coefficients of Cu and Al, which can significantly reduce thermal stress. In addition, adding Cr and Zr to Al-Cu alloy can make the alloy show a positive interaction, so that the alloy elements become a network structure. Figure 6 , a multi-element Al-based alloy electrode with uniform texture can be obtained, thereby effectively inhibiting the migration of Al and Cu atoms. At the same time, the addition of Cr and Zr can also weaken the preferential sputtering caused by the difference in injection effect during magnetron sputtering, making the target material more uniformly sputtered, such as Figure 8 The film quality is more uniform. Doping only one of Cr or Zr cannot achieve the effect of doping both metals at the same time. Adding Cr and Zr can also improve the poor bonding strength between traditional aluminum-copper alloy and substrate (heat storage layer) and protective film (SIALON). Figure 7 shown.

[0044] Electrode 1 uses an alloy with Al as the main component. In addition to having the above advantages, it can also simplify the process. The etching process can basically maintain the same process as that of electrode 2, and electrode 2 can be well combined with electrode 2 (pure aluminum). This is because the bonding force of the same metal materials should have better compatibility.

[0045] Al / Cu alloy targets are made using a vacuum induction melting furnace and a graphite crucible. The Al matrix is ​​made of 99.99% aluminum particles, and the Cu, Cr, and Zr components are made of high-purity particles (Cu ≥ 99.99%, Cr ≥ 99.95%, Zr ≥ 99.95%). The raw materials remain molten in the melting furnace for a long time, and the liquid is in a high-temperature, high-vacuum environment. The temperature, vacuum degree, and heating power need to be controlled at all times. Inert gas (e.g., Ar) can also be filled in and a deoxidizer can be added to prevent oxidation and boiling.

[0046] On the surface of the substrate where the heating resistor has been made, the alloy target is used to plate an alloy film of about 1 μm by magnetron sputtering. Before the electrode is patterned, in order to make the alloy more evenly distributed, -4 Solution treatment at temperatures below 550°C in a Pa vacuum environment improves corrosion resistance. To achieve better conductivity, solution treatment is followed by annealing at 150-200°C, allowing a very small amount of solid solution components to precipitate and form a dispersed distribution, which can reduce the resistivity of the alloy and improve conductivity. After heat treatment, weak bonds, vacancies, and lattice defects are reduced, making the resistivity of the alloy closer to that of Al / Cu alloys.

[0047] Then apply positive photoresist and perform photolithography, retaining only the high-temperature part of the photoresist close to the heating resistor, and perform etching. After etching, a wet etching process such as mixed acid is used to remove the alloy without photoresist protection to form an electrode pattern.

[0048] In the low-temperature region away from the heating resistor, individual electrodes 4a and common electrodes 4b are formed using similar thin-film and patterning processes. To ensure good solderability with the IC, electrode 2, located away from the heating resistor, is made of pure aluminum. Electrodes 1 and 2 overlap and conduct electricity. To ensure good conductivity, the overlap area is at least 20 μm. The patterning process for electrode 2 is the same as for electrode 1.

[0049] In order to determine the film quality, XRD detection, scratch adhesion detection, four-probe square resistance detection, laser stress testing and other means can be used to characterize and inspect the film quality.

[0050] After the film quality inspection is passed, an insulating layer is formed on the electrode. The insulating layer is made of SIALON film. SIALON has excellent insulation performance and can prevent external ions, water vapor, etc. from corroding the electrodes and heating resistors. According to the need for wear resistance, a wear-resistant layer is formed on the insulating layer. The wear-resistant layer is made of SIC film. SIC has high hardness and can play a good role in scratch resistance and wear resistance.

[0051] Compared with the prior art, the present invention sets an aluminum-based alloy electrode wire at least in the high-temperature area (within 300 μm from the heating resistor), so that the wire electrode shows a positive interaction while maintaining a low expansion coefficient, making the alloy texture uniform, thereby effectively inhibiting the migration of Al and Cu atoms, and improving the problem of poor bonding between the traditional Cu component and the substrate and protective film. It can also weaken the preferential sputtering caused by the difference in injection effect during magnetron sputtering, so that the target material is sputtered more evenly and the generated film quality is also more uniform. The obtained wire electrode has better adhesion, heat dissipation, conductivity and low thermal stress, which can significantly improve the service life and quality of the product.

[0052] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for manufacturing a thin film thermal print head, wherein: The thin film thermal print head is provided with an insulating substrate, a bottom glaze layer is provided on the surface of the insulating substrate, a heating resistor and an electrode wire are provided on the bottom glaze layer, and the electrode wire within at least 300 μm from the heating resistor is an aluminum-based alloy electrode wire, wherein the aluminum-based alloy electrode wire contains metal aluminum, metal copper, metal chromium, and metal zirconium, wherein metal copper accounts for less than 5% of the total mass proportion of the aluminum-based alloy electrode wire, metal chromium and metal zirconium account for less than 1% of the total mass proportion of the aluminum-based alloy electrode wire, and the rest is metal aluminum; first, the bottom glaze layer is formed on the surface of the insulating substrate, and then the heating resistor and the electrode wire are formed on the bottom glaze layer on the insulating substrate, the electrode wire includes the aluminum-based alloy electrode wire, and the formation of the aluminum-based alloy electrode wire includes the following steps: Step 1: Prepare Al / Cu alloy target using a vacuum induction melting furnace and graphite crucible. The Al matrix uses 99.99% aluminum particles, and the Cu, Cr, and Zr components use high-purity particles, where Cu ≥ 99.99%, Cr ≥ 99.95%, and Zr ≥ 99.95%. The raw materials remain molten in the melting furnace for a long time. The liquid is in a high-temperature, high-vacuum environment. The temperature, vacuum degree, and heating power are controlled. Inert gas and deoxidizer are added as needed to prevent oxidation and boiling. Step 2: On the surface of the insulating substrate where the heating resistor has been made, use the alloy target material obtained in step 1 to plate an alloy film by magnetron sputtering with a thickness of 1±0.5um. In order to make the alloy more evenly distributed, -4 Solution treatment is carried out below 550℃ in a Pa vacuum environment to improve corrosion resistance. In order to obtain better conductivity, after solution treatment, annealing treatment is carried out at 150-200℃ to precipitate a very small amount of solid solution components to form a dispersed distribution, reduce the resistivity of the alloy, and improve conductivity; Step 3: Electrode patterning: Apply positive photoresist and perform photolithography to retain the high-temperature area within 0~300um from the heating resistor and perform imaging. After imaging, use a wet etching process to remove the alloy without photoresist protection to form an electrode pattern.

2. The method for manufacturing a thin film thermal print head according to claim 1, characterized in that: The ratio of chromium Cr in the aluminum-based alloy electrode wire to the total mass percentage of chromium Cr and zirconium Zr is between 35-65%.

3. The method for manufacturing a thin film thermal print head according to claim 1, characterized in that: The electrode wire adopts a two-section overlapping structure, wherein the electrode wire within 300um from the heating resistor adopts an aluminum-based alloy electrode wire, and the electrode wire greater than 300μm from the heating resistor adopts a pure aluminum wire. The aluminum-based alloy electrode wire and the pure aluminum wire are overlapped to form an electrical connection. The thickness of the electrode wire is 1±0.5μm, and the overlapping area is at least 20um.

4. The method for manufacturing a thin film thermal print head according to claim 1, wherein: The upper surface of the electrode wire is further provided with a protective layer, which includes an insulating layer, and the insulating layer is prepared by using a thin film.

5. The method for manufacturing a thin film thermal print head according to claim 3, characterized in that: In the manufacturing method of a thin film thermal print head, if pure aluminum wire is used for the electrode wire that is more than 300 μm away from the heating resistor, then in step 3, only the positive photoresist within a distance of 0-300 μm from the heating resistor is retained, thereby forming an aluminum-based alloy electrode wire only within a range of 0-300 μm from the heating resistor. Thereafter, an Al target is used to sputter an Al thin film above the aluminum-based alloy electrode wire, and through electrode patterning, an Al electrode wire that is more than 300 μm away from the heating resistor and overlaps the aluminum-based alloy electrode wire by at least 20 μm is obtained.

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