Spliced thermal printhead and method of manufacturing the same

Abstract

The present application relates to the technical field of thermal printing head manufacturing, in particular to a spliced thermal printing head suitable for wide printing and capable of avoiding the collapse of adjacent spliced units due to thermal stress and effectively improving printing quality, and a manufacturing method thereof, which is provided with a metal heat dissipation platform, the upper surface of the metal heat dissipation platform is provided with two or more than two thermal printing units adjacent to each other, characterized in that a composite ceramic lining with a thermal expansion coefficient of 4x10 ‑6 ‑9x10 ‑6 mm / ℃ is arranged on the upper surface of the metal heat dissipation platform, the thickness of the lining ranges from 0.3 to 3.0 mm, two or more than two thermal printing units adjacent to each other are arranged on the lining, and the lining is a ceramic film made of high-purity alumina with more than 96% of silicon carbide added.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermal printing head manufacturing, in particular to a spliced thermal printing head suitable for wide printing and capable of avoiding the collapse of adjacent spliced units due to thermal stress and effectively improving printing quality. BACKGROUND

[0002] As known, a plurality of thermal heating body units are linearly arranged on the thermal printing head according to a certain resolution, and the thermal heating body units generate Joule heat effect by applying a corresponding pulse voltage to each heating body unit to convert the applied electrical energy into heat energy, and the heat energy generated by the heating body units is used to act on the thermal medium to make the thermal medium develop color.

[0003] In the fields of large-format advertising photos, power signs, soft packaging, etc., inkjet printing is generally used, and ink cartridges and toner cartridges are consumables for inkjet printing, which causes great burden to the environment. Thermal printing is a direct printing or transfer printing of graphic information on thermal paper or color ribbon by the color development of the printing head. In addition to thermal paper and color ribbon, no other consumables are required, which is green and environmentally friendly. In addition, thermal printing is fast and has high resolution, and can achieve fine printing of 300 dpi or above. The printing width of a thermal printing head is from 4.2 mm to 216 mm, which is a conventional specification. Now, as the application field needs, the printing width has been expanded to about 300 mm. However, the above-mentioned applications such as advertising photos require a width of more than 1 m, and the current specifications cannot meet the application, so the only way to achieve wide printing is to splice the printing heads.

[0004] The existing thermal printing head is mainly composed of a ceramic substrate, a PCB circuit board and a metal heat sink. In general, the thermal conductivity coefficient of ceramic material at room temperature is only 5-24 W / m·K, so the ceramic substrate can complete the heat storage and heat preservation function in the initial printing stage to improve the printing density of the initial printing area. However, as the printing time is prolonged, the heat accumulation effect is intensified, and the excessive heat accumulation not only causes the printing to be too deep, but also easily damages the electrical devices on the thermal printing head. Therefore, the ceramic substrate of the thermal printing head needs to be arranged on a metal base with good heat dissipation performance to ensure heat dissipation during long-time continuous printing.

[0005] For a spliced wide thermal printing device, a plurality of spliced unit bodies (thermal printing units) are arranged closely on the metal heat dissipation base. Obviously, the smaller the joint gap between the spliced unit bodies, the better the overall printing effect. However, due to the difference in thermal expansion of different materials during temperature change, the relative thermal displacement amount is inconsistent, which may cause the substrate at the joint gap to be squeezed and the substrate to be collapsed, and other product defects. At the same time, the difference in thermal expansion coefficient causes the substrate to be bent and deformed when the epoxy resin glue is heat-cured, and the width of the surface of the long-size substrate fluctuates greatly, which affects the printing effect.

[0006] The invention patent with the patent number 201820918273.8 and the name of a spliced thermal print head records the substrate splicing method, and the shape of the spliced substrate is required to be processed, and the patent number 200920309388.8 mainly processes the resistance value at the spliced joint to avoid low density at the spliced joint. The above-mentioned patent solves the problem of uneven density by splicing the method of the print head and processing the resistance value at the spliced joint. However, the print head is at high temperature during printing, and the difference in thermal expansion coefficient between different materials is not considered. There are a series of problems of poor printing caused by extrusion and tooth of the substrate at the spliced joint and bending deformation of the long size. The spliced joint of the above-mentioned spliced thermal print head device has a significant difference due to thermal expansion and contraction. The spliced joint width d2 needs to be kept more than 0.4mm, and in order to realize seamless, at least 5 or more heating body overlapping points are required to be ensured, which cannot meet the requirement of high printing quality. SUMMARY

[0007] The present application provides a spliced thermal print head and a manufacturing method thereof, which has reasonable structure, simple process and can significantly improve the wide printing quality.

[0008] The present application achieves the following measures:

[0009] A spliced thermal print head is provided with a metal heat dissipation platform, and the upper surface of the metal heat dissipation platform is provided with two or more thermal print units adjacent to each other, characterized in that a composite ceramic lining with a thermal expansion coefficient of 4x10 -6 -9x10 -6 mm / ℃ is arranged on the upper surface of the metal heat dissipation platform, the thickness of the lining ranges from 0.3mm to 3.0mm, and two or more thermal print units adjacent to each other are arranged on the lining. The lining is a ceramic film made of more than 96% high-purity alumina and silicon carbide.

[0010] The lining is made of Al2O3 ceramic powder and more than 5% of nano-SiC particles or silicon carbide whiskers by volume, so that the lining has good thermal shock resistance and heat conduction performance. Specifically, when the volume fraction of SiC is more than 5%, the critical thermal shock temperature difference of the obtained composite ceramic lining is increased from 70℃ to 185℃, so that the thermal print units adjacent to each other on the upper side of the lining are not affected by the thermal stress of the metal heat dissipation platform below.

[0011] The two or more heat-sensitive printing units adjacent to each other in the application include staggered B-type heat-sensitive printing units and C-type heat-sensitive printing units, the insulation ceramic substrate of the B-type heat-sensitive printing unit is narrow on the paper side and wide on the paper feeding side, the insulation ceramic substrate of the C-type heat-sensitive printing unit is wide on the paper side and narrow on the paper feeding side, further, the heating elements at the corresponding joint seams of the adjacent B-type heat-sensitive printing unit and C-type heat-sensitive printing unit are located on the same joint plane and staggered up and down in parallel with each other, and at least 2 heating points are overlapped.

[0012] The heat-sensitive printing unit in the application includes an insulation ceramic substrate, the surface of the insulation ceramic substrate is provided with a heat storage glaze coating, a heating resistor and an electrode wire, wherein the heating resistor and the electrode wire are further provided with a protective layer, the pin end of the electrode wire is connected with a driving IC through pressure welding or flip chip welding, the external circuit board or the flexible circuit board of the external control end is connected with the driving IC through pressure welding pads or flip chip welding, and the IC, the bonding site and the exposed electrode wire area are covered with epoxy resin glue; further, the protective layer is provided with an insulation protective layer, the material of the insulation protective layer is SION or SIALON, the upper surface of the insulation protective layer is provided with a silicon carbide protective layer, because the film layer is prone to form a protrusion at the edge due to tension in the sintering process, which leads to the decrease of the joint seam density and affects the flatness of the joint surface, and under the condition of cold and hot changes, the film layer is prone to be peeled off and warped due to the extrusion of the film layer on both sides of the joint seam, therefore, the insulation protective layer is provided starting from 0.1 mm away from the edge of the substrate, the C-SIC layer is provided on the insulation protective layer through a magnetic control sputtering method or the like, starting from 0.3 mm away from the edge of the substrate, and the SiO2 is provided on the silicon carbide, starting from 0.5 mm away from the edge of the substrate, so that a stepped protective layer is formed at the joint, at this time, because the film coating edges of the film layers in the protective layer are not concentrated, each protective film can effectively release the film stress at the film layer edge, avoiding the film layer from falling off due to excessive stress, and the concave at the joint can effectively avoid the problems of color band scratching and other printing consumables when the thermal transfer ribbon or other printing consumables pass through.

[0013] The application further provides a manufacturing method of the joint heat-sensitive printing head, and the manufacturing method comprises the following steps.

[0014] Step 1: preparing a buffer layer on the surface of a metal heat dissipation platform:

[0015] Step 1-1: obtaining a nano-scale mixed powder for preparing the buffer layer: adopting alumina with a purity of more than 96%, nano-scale silicon carbide particles or silicon carbide whiskers, and obtaining a nano-scale composite powder after ball milling and screening into fine powder;

[0016] Step 1-2: obtaining a buffer layer with a thickness of 0.3-3.0 mm on the metal heat dissipation platform through a spraying process or a deposition process;

[0017] Step 2: preparing the spliced thermal printing unit, including the B-type thermal printing unit and the C-type thermal printing unit, cutting the substrate by the dicing process, and controlling the substrate cutting precision to 30 microns;

[0018] Step 3: interlacing the B-type thermal printing unit and the C-type thermal printing unit on the upper surface of the liner obtained in step 1, and fixing them by adhesive, wherein the heating resistors of the adjacent B-type thermal printing unit and C-type thermal printing unit are located in the same splicing plane, and are staggered up and down parallel to each other, and overlap no more than 2 heating points.

[0019] In step 1-1 of the present application, the ratio of alumina to silicon carbide powder is 52%-65%: 35%-48% by volume percentage, a nano-sized composite liner is prepared by ball milling and other processes, alumina with a purity of more than 96% is mixed with nano-sized silicon carbide, and the mixture is ball milled and sieved into fine powder, at this time, the mixed powder is subjected to strong plastic deformation, repeated welding and fracture under the action of steel ball collision, resulting in a sharp increase in internal defect density, the grain size reaches the nano level, and the mixed powder is further refined and uniformly and dispersedly distributed to form a nano composite powder.

[0020] In step 1-2 of the present application, in order to fully combine the liner with the bottom metal heat sink, the liner formed by spraying or deposition has a thickness of not less than 0.3 mm, the liner needs to fully relieve the difference in thermal expansion coefficient between the metal heat sink and the alumina ceramic substrate, and adapt to the thermal conductivity of high-speed printing and consider the processing cost, the upper limit of the thickness of the liner is not more than 3 mm: the thermal expansion coefficient of the liner is equivalent to that of the ceramic substrate, and the thermal conductivity is 4-7 times that of the alumina ceramic substrate used as the thermal printing ceramic substrate, which can meet the heat dissipation requirements of the print head of high-speed printing, in addition, the liner formed by spraying or deposition does not undergo high-temperature sintering, and there is no obvious substrate deformation, which is more convenient for bonding the heating substrate and the liner.

[0021] In step 3 of the present application, the MARK pattern formed by laser cutting of the insulating substrate in the spliced printing unit is used as the alignment pattern for precise substrate cutting, achieving high-precision cutting and X, Y direction precise splicing seam, and the splicing seam size is controlled to 80 microns.

[0022] The present application is aimed at the multiple thermal printing units in the prior art spliced thermal printing head, due to the change of ambient temperature after splicing, the product problems such as the substrate extrusion and the substrate edge collapse at the splicing seam, and proposes a thermal printing unit suitable for splicing, which has strong weather resistance, high printing quality, fast printing speed and can meet the demand of 1m or more wide printing, and a thermal printing head, by setting a lining layer with a thermal expansion coefficient equivalent to that of the ceramic substrate between the metal heat dissipation base and the thermal printing unit, the influence of the stress generated by the metal heat dissipation plate under heat on the thermal printing unit is effectively relieved under the premise of ensuring good heat dissipation effect of the thermal printing unit during operation, thereby avoiding the problems such as the extrusion, rupture and bending of the ceramic substrate during the operation of the spliced thermal printing head. BRIEF DESCRIPTION OF DRAWINGS

[0023] FIG. 1 is a sectional structure diagram of the present application. Figure 1

[0024] FIG. 2 is a second sectional structure diagram of the present application. Figure 2

[0025] FIG. 3 is a third sectional structure diagram of the present application. Figure 3

[0026] FIG. 4 is a structure diagram of the present application. Figure 4

[0027] FIG. 5 is a setting diagram of the heating resistor body in the adjacent thermal printing unit in the present application. Figure 5

[0028] FIG. 6 is a structure diagram of the B-type thermal printing unit and the C-type thermal printing unit staggered splicing in the present application. Figure 6

[0029] FIG. 7 is a protective layer structure diagram of the adjacent thermal printing unit in the present application. Figure 7

[0030] FIG. 8 is a comparative curve diagram of the heating body bending amount in embodiment 1 of the present application and the heating body bending amount of the traditional spliced thermal printing device. Figure 8

[0031] FIG. 9 is a comparative curve diagram of the heating body bending amount change at different temperatures in embodiment 1 of the present application. Figure 9

[0032] FIG. 10 is a fluctuation amount curve diagram of the heating resistor body and the edge of the thermal printing unit in embodiment 3 of the present application. Figure 10

[0033] FIG. 11 is a comparative curve diagram of the heating resistor body bending degree change with temperature in embodiment 2 and embodiment 1 of the present application under the same printing width. Figure 11 ​​​​​​​​​​​

[0034] The figure marks: the lining layer 1, the heat-sensitive printing heat-generating substrate 2, the circuit board 3, the adhesive tape 4, the heat-accumulating glaze coating 5, the heat-generating resistor 6, the electrode wire 7, the protective layer 8, the first insulating protective layer 81, the silicon carbide protective layer 82, the SiO2 protective layer 83, the driving IC 9, the epoxy resin layer 10, the anisotropic conductive adhesive film layer 11, the ultraviolet glue 12, the heat-conducting silicone or heat-conducting silicone grease 13, the metal heat-dissipating platform 14, the B-type heat-sensitive printing unit 15, the C-type heat-sensitive printing unit 16. DETAILED DESCRIPTION

[0035] The present application is further illustrated below in conjunction with the drawings and examples.

[0036] Example 1

[0037] As shown in the drawings Figure 1 and the drawings Figure 2 , the present example provides a spliced heat-sensitive printing head and a manufacturing method, the present example is provided with a metal heat-dissipating platform 14, the upper surface of the metal heat-dissipating platform 14 is provided with two or more heat-sensitive printing units adjacent to each other, wherein the upper surface of the metal heat-dissipating platform 14 is provided with a composite ceramic lining layer 1 of silicon carbide and aluminum oxide with a thermal expansion coefficient of 4.5x10 -6 mm / ℃, the thickness of the lining layer 1 is 1 cm, and the two or more heat-sensitive printing units adjacent to each other are arranged on the lining layer;

[0038] In the present example, the composite thermal expansion coefficient of the heat-sensitive printing head heat-generating substrate in the heat-sensitive printing unit is about 4.7x10 -6 mm / ℃, the thermal conductivity of the lining layer 1 is slightly lower than that of the heat-generating substrate, which can effectively avoid the problem of extrusion deformation at the joint, and seamless splicing can be realized, the lining layer 1 in the present example is made of nano-SIC powder with a volume percentage controlled within 50% and aluminum oxide powder with a purity of more than 96% during preparation, and the thermal conductivity of the obtained lining layer 1 is 28-30 W / m.K.

[0039] The heat-sensitive printing unit described in the present example is provided with a heat-sensitive printing heat-generating substrate 2 as shown in the drawings Figure 1 or the drawings Figure 2 , the heat-sensitive printing heat-generating substrate 2 is provided with a heat-accumulating glaze coating 5, the upper side of the heat-accumulating glaze coating 5 is provided with a heat-generating resistor 6 and an electrode wire 7, the electrode wire 7 is further connected to the functional circuit on the circuit board 3 through a driving IC 9, and the upper side of the heat-generating resistor 6 and the electrode wire 7 is further provided with a protective layer 8, the protective layer 8 includes a first insulating protective layer 81 and a wear-resistant layer 82.

[0040] The spliced heat-sensitive printing head described in the present example is prepared by the following method:

[0041] Step 1: Obtain the nano-composite powder required for preparing the backing layer: take the components in the volume percentage of 55%:45% of alumina and silicon carbide, the alumina uses alumina with a purity of more than 96%, and the silicon carbide uses nano-sized silicon carbide powder, which is finely powdered through ball milling and screening. The mixed powder, under the impact of steel ball collision, undergoes strong plastic deformation, repeated welding and fracture, resulting in a sharp increase in internal defect density, and the grain size reaches the nano level. At the same time, it is further refined and uniformly and dispersedly distributed to form a nano-composite powder. In this example, SiC nanoparticles are added to Al2O3 ceramic powder. Performance verification shows that when the volume fraction of SiC powder added is more than 5%, the thermal shock resistance of the ceramic can be significantly improved, and the critical thermal shock temperature difference of alumina ceramic can be increased from 70°C to 185°C.

[0042] Step 2: Form a backing layer with a thickness of not less than 0.3mm on the upper surface of the metal heat sink 14 by spraying process, specifically:

[0043] A cold spraying system is used to prepare the silicon carbide and alumina nano-composite ceramic coating, which includes a high-pressure gas source, a control cabinet, a cold spraying gun, a high-pressure powder feeder, and a high-pressure gas heater. The spraying gun is a key component of the cold spraying system, which is a converging-diverging Laval nozzle with a throat diameter of 2mm. Nitrogen is used as the accelerating gas and powder feeding gas during the spraying process. The specific spraying parameters are shown in Table 1. The substrate material used in this example is pure aluminum plate, and the sample size is 1500mm x 10mm x 5mm. Before spraying, 700μm(24 mesh) brown corundum sand is used for sandblasting treatment

[0044]

[0045] In this example, a composite ceramic backing layer with a thickness of 0.3-3mm and a length of 1.515m is bonded to the upper surface of the metal heat sink by spraying on a 1.6m metal heat sink.

[0046] Step 3: Prepare the thermal printing unit for splicing, including B-type thermal printing unit and C-type thermal printing unit. Specifically, design the B-type structure(out paper side narrow, paper side wide) and C-type structure(out paper side wide, paper side narrow) of the two monomers, wherein the insulation substrate of the splicing printing unit uses a heating element structure and wiring design that does not affect splicing and cutting, and the MARK pattern formed by scribing and cutting is used as the alignment pattern for precise substrate cutting, achieving high-precision cutting and precise splicing in X and Y directions.

[0047] Step 4: Interleave and fix the B-type thermal printing unit and C-type thermal printing unit on the surface of the backing layer obtained in step 1, as shown in the attached Figure 6As shown, the B-outer structure and the C-outer structure print heads are arranged alternately, and the substrate is cut by laser with low precision of about 0.05mm, the thermal expansion coefficient of the metal heat dissipation plate 14 and the lining layer is 4.0-9.0x10 -6 mm / ℃, the relative thermal displacement of the two during the print head storage and printing process is basically the same, so theoretically, the gap d2 between the adjacent monomers of the ceramic substrate in the X direction can be set to 0mm, and usually for safety, d2>0.08mm, and the heating resistor bodies on both sides of the gap are staggered and overlap at most 2 heating points, as shown in the accompanying Figure 5 illustration, achieving seamless splicing.

[0048] In this example, the thickness of the lining layer 1 is not less than 0.3mm, because the lining layer needs to fully alleviate the difference in thermal expansion coefficient between the metal heat dissipation plate and the thermal sensitive printing ceramic substrate, and a thickness lower than 0.3mm will cause the lining layer 1 to be easily deformed or cracked. In addition, the lining layer 1 needs to meet the heat dissipation requirements during continuous high-speed printing, so the thickness of the lining layer is not more than 3mm.

[0049] The thermal expansion coefficient of the lining layer 1 obtained by the example is similar to that of the thermal sensitive printing ceramic substrate in the spliced thermal sensitive printing unit, and the thermal conductivity is 4-7 times that of ordinary ceramic substrates (mainly alumina ceramic), which can meet the heat dissipation requirements of the print head during high-speed printing. In addition, the lining layer formed by spraying in this example does not undergo high-temperature sintering, and there is no obvious substrate deformation, which is more convenient for the thermal sensitive printing unit and the lining layer to be bonded and used, thereby obtaining a spliced thermal sensitive printing device with better flatness of the heating resistor body.

[0050] Comparing the spliced thermal sensitive printing device obtained by the example with the traditional spliced thermal sensitive printing device, as shown in the accompanying Figure 8 illustration, under the same width conditions, the flatness of the heating resistor body of the spliced thermal sensitive printing device obtained by the example is better.

[0051] Further limiting the printing width to 303mm, the spliced thermal sensitive printing device obtained by the example and the traditional spliced thermal sensitive printing device are continuously high-speed printed, and as the printing time increases, the temperature of the heating resistor body gradually rises, as shown in the accompanying Figure 9 illustration, the measured curve of the bending amount of the heating resistor body with the increase of temperature shows that under the same printing width conditions, the bending amount of the heating resistor body of the spliced printing device obtained by the example is significantly smaller than that of the traditional spliced thermal sensitive printing device, thereby effectively showing that the example can overcome the adverse effects of bending deformation caused by thermal stress.

[0052] Example 2:

[0053] This example presents a spliced ​​thermal printhead, comprising a bottom metal heat sink 14, a liner 1 on the metal heat sink 14, and tightly spliced ​​thermal printing units on the upper surface of the liner 1. In this example, the liner 1 is made of alumina and silicon carbide powder in a volume percentage ratio of 52%-65%:35%-48%. Furthermore, this example uses the method described in the attached... Figure 3 The structure shown has a thickness of 0.6-15mm for the liner 1. Grooves are formed on the surface of the liner 1, and the grooves are filled with 0.3mm thick thermally conductive silicone or thermally conductive grease.

[0054] In this example, the lower surface of the heating substrate 2 for the thermal printhead in the thermal printing unit is fixedly connected to the liner 1 via thermally conductive silicone or thermally conductive grease, which can further improve the heat conduction and heat dissipation effect. The groove is formed on the upper surface of the liner 1 in the area corresponding to the heating resistor 6 on the heating substrate 2 for the thermal printhead. The heating resistor 6 is in full contact with the liner 1 for heat dissipation. The width of the groove is slightly wider than the width of the heating resistor 1, resulting in a larger and stronger bonding area. Therefore, the width range of the groove is limited to 0.2-0.5mm.

[0055] This example significantly improves the local thermal conductivity of the liner 1 corresponding to the heating resistor area by adding grooves and thermally conductive silicone or thermal grease. This allows the liner thickness to be maintained within a relatively large range, thus better isolating the thermal stress of the metal heat sink 14 and significantly reducing the fabrication difficulty of the liner. Simultaneously, the grooves effectively alleviate various stresses; as shown in the attached figure. Figure 11 As shown, under the condition of equal printing width, compared with Example 1, the heating resistor in this example bends less as the temperature increases, resulting in better printing effect.

[0056] Example 3:

[0057] This example proposes a spliced ​​thermal printhead, which has a metal heat sink 14 at the bottom, a liner 1 on the metal heat sink 14, and a tightly spliced ​​thermal printing unit on the upper surface of the liner 1. The liner 1 is the same type as that in Example 1. In this example, the liner 1 is obtained by a deposition process: molten AL matrix metal liquid is atomized and sprayed outward in a high-speed flowing inert gas, and composite ceramic particles are added to the atomized metal liquid at the same time, so that the two are mixed during the sedimentation process, and finally deposited together on the pretreated AL matrix to obtain the desired composite ceramic liner.

[0058] As attached Figure 7As shown, the protective layer 8 of the adjacent thermal printing unit in this example has a stepped structure: the insulating protective layer 81 is arranged starting from 0.1 mm away from the edge of the substrate, the C-SIC silicon carbide protective layer 82 is arranged on the insulating protective layer 81 by a magnetron sputtering method or the like, and is arranged starting from 0.3 mm away from the edge of the substrate, the SiO2 protective layer 83 is further arranged on the silicon carbide protective layer 82, and is arranged starting from 0.5 mm away from the edge of the substrate, so that a stepped structure is formed at the splicing position.

[0059] In the conventional splicing thermal printing device, the edge glaze layer of the heating resistor at the splicing position is tightened due to stress, and is higher than that far away from the edge, which is generally called the horn phenomenon, resulting in large fluctuations of the edge glaze layer: the width is 30-40 microns, and the fluctuation amount is 6-10 microns; by using the stepped protective layer of this example, the edge protrusion is effectively reduced, such as Figure 10 As shown, the edge protrusion is reduced to within 20 microns, and the fluctuation amount of the heating resistor is reduced to within 5 microns, so as to be beneficial to obtain higher printing quality.

[0060] The manufacturing method provided by the present application can effectively alleviate the edge extrusion of the substrate at the splicing position caused by the difference in the thermal expansion coefficient between different materials, and avoid the expansion of the crack at the splicing position caused by the shrinkage during cooling, so as to prevent the incomplete splicing of the printing and the obvious blank printing.

Claims

1. A splicing thermal printhead, comprising a metal heat sink, wherein two or more adjacent thermal printing units are disposed on the upper surface of the metal heat sink, characterized in that... The surface of the metal heat sink has a thermal expansion coefficient of 4 x 10. -6 -9x10 -6 A composite ceramic liner with a thickness ranging from 0.3 to 3.0 mm / ℃, wherein two or more adjacent thermal printing units are disposed on the liner, and the liner is a ceramic film made of high-purity alumina with silicon carbide added to a purity of over 96%. The liner is made of Al2O3 ceramic powder and nano-SiC particles or silicon carbide whiskers with a volume percentage of more than 5% of the total, thereby giving the liner good thermal shock resistance and thermal conductivity. Two or more adjacent thermal printing units include staggered B-type thermal printing units and C-type thermal printing units. The insulating ceramic substrate of the B-type thermal printing unit is narrow on the paper output side and wide on the paper input side, while the insulating ceramic substrate of the C-type thermal printing unit is wide on the paper output side and narrow on the paper input side. The thermal printing unit includes an insulating ceramic substrate. The surface of the insulating ceramic substrate is provided with a heat-storing glaze coating, a heating resistor, and electrode wires. The heating resistor and electrode wires are also provided with a protective layer. The protective layer has an insulating protective layer starting 0.1 mm from the edge of the substrate, a C-SiC layer starting 0.3 mm from the edge of the substrate on the insulating protective layer, and a SiO2 layer starting 0.5 mm from the edge of the substrate on the silicon carbide, thereby forming a stepped shape at the splicing point. The B-type thermal printing unit and the C-type thermal printing unit are staggered and spliced ​​on the upper surface of the substrate and fixed with adhesive.

2. The splicing thermal printhead according to claim 1, characterized in that, The heating elements at the seams of adjacent Type B thermal printing units and Type C thermal printing units are located on the same splicing plane, are parallel to each other and staggered vertically, and overlap by at least two heating points.

3. A method for manufacturing a splicing thermal printhead as described in any one of claims 1-2, characterized in that, Includes the following steps: Step 1: Prepare a liner on the upper surface of the metal heat sink: Step 1-1: Obtaining nanoscale mixed powder for preparing the liner: using high-purity alumina (96% or higher) and nanoscale silicon carbide particles or silicon carbide whiskers, the nanoscale composite powder is obtained after ball milling and screening into fine powders; Steps 1-2: Using a spraying or deposition process, obtain a liner with a thickness of 0.6-3.0 mm on the metal heat sink; Step 2: Prepare the thermal printing unit for splicing, including the B-type thermal printing unit and the C-type thermal printing unit. The substrate is cut using a dicing process, and the substrate cutting accuracy is controlled within 30 micrometers. Step 3: Interlock the type B thermal printing unit and the type C thermal printing unit on the upper surface of the liner obtained in step 1, and fix them with adhesive. The heating resistors of adjacent type B thermal printing units and type C thermal printing units are located on the same splicing plane, are parallel to each other and staggered vertically, and overlap by no more than 2 heating points.

4. The manufacturing method of a splicing thermal printhead according to claim 3, characterized in that, In step 1-1, the ratio of alumina to silicon carbide powder is 52%:48%-65%:35% by volume. A composite liner with nanoscale particle size is prepared by ball milling and other processes. High-purity alumina (96% or higher) and nanoscale silicon carbide or aluminum silicon carbide are ball-milled and screened into fine powders. Under the impact of steel balls, the mixed powder undergoes strong plastic deformation, repeated welding and fracture, which leads to a sharp increase in the density of internal defects and the grain size reaches the nanoscale. At the same time, it is further refined and uniformly and diffusely distributed to form nanocomposite powder. The mixed powder is then made into composite ceramic powder.

5. The manufacturing method of a splicing thermal printhead according to claim 3, characterized in that, In steps 1-2, in order to fully bond the liner with the bottom metal heat sink, the thickness of the liner formed by spraying or deposition should not be less than 0.3mm. The liner needs to fully mitigate the difference in thermal expansion coefficients between the metal heat sink and the alumina substrate, and take into account the thermal conductivity and processing cost considerations for high-speed printing. The upper limit of the liner thickness should not exceed 3mm. The thermal expansion coefficient of the liner is comparable to that of the ceramic substrate, while the thermal conductivity is 4-7 times that of the alumina substrate, which can meet the heat dissipation requirements of the printhead in high-speed printing. In addition, the liner formed by spraying or deposition does not undergo high-temperature sintering, and there is no obvious substrate deformation, which makes it easier to bond the heat-generating substrate and the liner for use.

6. The manufacturing method of a splicing thermal printhead according to claim 3, characterized in that, In step 3, the insulating substrate in the splicing printing unit uses the MARK pattern formed by laser cutting as the alignment pattern for precise substrate cutting, achieving high-precision cutting and precise splicing in the X and Y directions, with the splicing size controlled within 80 micrometers.

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