Thick film heater with layer-by-layer retreating identification structure and processing method thereof

Abstract

The invention relates to an electric heater technology, and aims to provide a thick film heater with a layer-by-layer retreating identification structure and a processing method thereof. Comprising the following steps: by taking a first target on the surface of a substrate as a positioning reference, coating and sintering the surface of the substrate in sequence to form an insulating dielectric layer and a resistive layer; continuously coating by taking the target in the resistive layer as a positioning reference, and sintering to form an electrode layer; continuously coating by taking the first target as a positioning reference, and sintering to form an encapsulation layer; the edges of the insulating dielectric layer, the resistive layer, the electrode layer and the encapsulation layer form local protruding parts at set areas, and the local protruding parts retract backwards while being stacked layer by layer to form a layer-by-layer withdrawing recognition structure. The layer-by-layer returning recognition structure design provided by the invention can be used for detecting the number of printing layers, measuring the actual thickness of each layer structure and detecting the positioning accuracy of each coating by an image recognition technology, and the comprehensive cost can be reduced while the quality stability is improved.

Description

Technical Field

[0001] The invention relates to electric heater technology, and in particular to a thick film heater with a layer-by-layer step-back identification structure and a processing method thereof. Background Art

[0002] In the field of electric heater technology, the concept of thick film is mainly relative to thin film, which refers to a film layer with a thickness of several microns to tens of microns formed on a substrate by printing and sintering technology. Thick film heating elements are made by printing insulating media, heating resistors, conductor materials, protective media and other materials on the heating element substrate in sequence using screen printing technology, and then sintering at high temperature. Stainless steel has excellent mechanical and thermal shock resistance, moderate cost, and easy processing, making it an ideal choice for substrates for high-power thick film circuits. Then, a slurry with a specific resistivity (usually metal oxides or other conductive materials) is coated on the substrate by screen printing and other methods, and then sintered at high temperature to form a strong and durable resistor layer (the pattern of the resistor layer needs to be designed according to the functional requirements of the product), and according to the design requirements, it is equipped with an electrode layer and a dielectric layer with a matching pattern, and heat can be generated when the power is turned on. This technology has a wide range of application cases in household appliances (such as water heaters), the automotive industry (such as for defrosting / fogging rearview mirrors), medical equipment, aerospace and other fields due to its advantages such as fast response time, high energy efficiency ratio and long service life.

[0003] In the production process of thick film heaters, since the insulating dielectric layer is usually relatively thick, it cannot be completed through one printing and sintering, and needs to be printed and sintered in multiple times. Therefore, in the final thick film heater product, the total number of layers may be more than 6 layers. When designing the product, there will be certain requirements for the thickness of each layer structure. Too thin may cause insulation failure, heating power imbalance, poor electrode firmness and other problems. Too thick will also cause large raw material loss, insufficient heating power and other problems. However, due to multiple printing and sintering, the layers of the structure will be fused due to in-situ coverage and high-temperature heating and cannot be peeled off layer by layer. Therefore, in the prior art, the thickness measurement test for the product can only infer the process control status of each layer by measuring the total thickness, and it is difficult to confirm whether the processing of each layer can meet the thickness requirements of the product design plan.

[0004] In addition, during the printing process of each layer, the existing scheme usually uses a target set on the substrate, and uses the image recognition technology of the CCD automatic alignment system to locate the operating range of the screen printing, so as to achieve in-situ coverage of the multi-layer structure as much as possible. Since the substrate will repeatedly undergo multiple high-temperature sinterings as the processing progresses, the color of the target will change during the process, making it difficult to identify during the image recognition process. There is also an existing technology that uses the target on the substrate when printing the first layer, and the subsequent layers use the pattern on the previous layer as the target for positioning, but this method will produce cumulative errors and cause interlayer misalignment. However, the inability to achieve precise positioning is a very serious technical problem, which is particularly critical for the subsequent printing of the electrode layer. Because the thick film heater has high requirements for temperature uniformity, there are higher requirements for resistance consistency. Unclear recognition or large positioning errors may cause the electrode layer and the resistor layer to be unable to accurately align, resulting in deviations in the length of the resistor track, and ultimately unqualified resistance consistency. There is even a misalignment between the electrode layer and the resistor layer, resulting in the serious consequence that the entire thick film heater cannot form a closed circuit and becomes scrapped.

[0005] Therefore, it is necessary to propose a new solution to solve the above technical problems. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a thick film heater with a layer-by-layer step-back identification structure and a resistance positioning target.

[0007] In order to solve the above technical problems, the solution adopted by the present invention is:

[0008] Provided is a thick film heater with a step-by-step stepped identification structure, the thick film heater comprising: a substrate, used as a supporting body of the thick film heater; a multilayer structure, located on the surface of the substrate, comprising an insulating dielectric layer, a resistor layer, an electrode layer and an encapsulation layer arranged in sequence from bottom to top, each formed by repeatedly coating and sintering corresponding slurries; a step-by-step stepped identification structure, located on the side edge of the multilayer structure, formed by superimposing local protruding portions of the insulating dielectric layer, the resistor layer, the electrode layer and the encapsulation layer in a step-by-step stepped manner; each layer in the structure has the same edge shape and maintains a spacing according to a set size.

[0009] As a preferred solution of the present invention, in the layer-by-layer step-back identification structure, each layer has straight edges that are parallel to each other and maintain the same spacing.

[0010] As a preferred solution of the present invention, in the layer-by-layer step-back identification structure, the straight edge of each layer is perpendicular to the edge of the adjacent multi-layer structure.

[0011] As a preferred solution of the present invention, the substrate is a flat plate or cylindrical structure made of metal or heat-resistant plastic material.

[0012] As a preferred solution of the present invention, the insulating dielectric layer has one or more layers.

[0013] As a preferred embodiment of the present invention, a first target for positioning is provided on the surface of the substrate and is located on the same side of the multilayer structure as the layer-by-layer step-back identification structure; the first target is located at the starting position of coating of the multilayer structure, and the layer-by-layer step-back identification structure is located at the ending position of coating of the multilayer structure.

[0014] As a preferred embodiment of the present invention, in the resistor layer, at least one second target for positioning and at least two wiring terminals for connecting the internal circuit of the resistor layer are formed by coating and sintering; in the electrode layer, at least two wiring electrodes for connecting the external circuit are formed by coating and sintering; the wiring terminals and wiring electrodes are arranged one by one, and the wiring terminals and wiring electrodes in each group are in contact with each other.

[0015] As a preferred solution of the present invention, the wiring terminals and wiring electrodes have a total of a plurality of even groups, and every two groups are correspondingly connected to a conductive loop in the resistance layer to achieve zoned or multi-stage heating control.

[0016] As a preferred solution of the present invention, the wiring terminals and the wiring electrodes are arranged in a cross-cross or right-angled manner.

[0017] As a preferred solution of the present invention, at least one of the wiring terminals is aligned with an edge of a certain insulating medium layer in the step-by-step step-back identification structure.

[0018] The present invention further provides a method for processing a thick film heater having a layer-by-layer step-back identification structure, comprising:

[0019] Forming a first target on the surface of the substrate, cleaning and drying it for later use;

[0020] Using the first target as a positioning reference, an insulating dielectric slurry is coated on the surface of the substrate, and an insulating dielectric layer is formed after sintering; this operation is repeated multiple times so that the total thickness of the insulating dielectric layer after stacking meets the requirements;

[0021] Using the first target as a positioning reference, the conductive paste is continuously coated on the surface of the insulating dielectric layer, and a resistance layer is formed after sintering; the pattern of the resistance layer includes the second target and at least one conductive loop, and each conductive loop includes two wiring terminals;

[0022] Using the second target as a positioning reference, the electrode slurry is continuously coated on the surface of the resistor layer, and the electrode layer is formed after sintering; the pattern of the electrode layer includes wiring electrodes arranged one by one corresponding to the wiring terminals in the resistor layer, and the wiring terminals in each group are in contact with the wiring electrodes;

[0023] Using the first target as a positioning reference, the insulating medium slurry is continuously coated on the surface of the electrode layer, and an encapsulation layer is formed after sintering; a plurality of window areas are reserved in the encapsulation layer, and each window area is arranged correspondingly to the wiring electrode in the electrode layer, so that the wiring electrode is exposed on the surface of the thick film heater;

[0024] The edges of each insulating medium layer, resistance layer, electrode layer and encapsulation layer form a local protrusion at a set area, and retreat backwards while being stacked layer by layer to form a layer-by-layer retreat identification structure.

[0025] As a preferred embodiment of the present invention, the slurry coating operation is performed by screen printing.

[0026] As a preferred solution of the present invention, when the electrode layer is formed by coating and sintering, the connection terminal is aligned with the edge of a certain insulating medium layer in the layer-by-layer step-back identification structure.

[0027] The present invention also provides a method for detecting the thickness of each coating in a thick film heater based on a layer-by-layer step-back identification structure, comprising: using a thickness gauge to measure the thickness of each step-back area in turn for the layer-by-layer step-back identification structure in the thick film heater; and obtaining the actual thickness of each layer structure by a calculation method of subtracting the thickness of adjacent step-back areas.

[0028] The present invention also provides a method for detecting the positioning accuracy of each coating in a thick film heater based on a layer-by-layer step-back recognition structure, including: using a camera to obtain an image of the layer-by-layer step-back recognition structure in the thick film heater, identifying and judging the spacing between the edges of each step-back area; if the spacing value between adjacent edges is within a threshold range, it is deemed to meet the requirements; if the spacing value between adjacent edges exceeds the threshold, it is deemed that there is a deviation in the coating positioning, and a warning message is issued.

[0029] As a preferred embodiment of the present invention, it further includes: using a camera to obtain images of the wiring terminals in the resistance layer and the layer-by-layer retreat identification structure, identifying and judging the alignment of the wiring terminals with the edge of a specified layer; if the alignment distance value between the two is within a threshold range, it is deemed to meet the requirements; if the alignment distance value between the two exceeds the threshold, it is deemed that there is a deviation in the positioning of the resistance layer, and a warning message is issued.

[0030] The present invention also provides a method for detecting the quality of thick film heater products by image recognition, comprising: after completing the preparation of the electrode layer or the encapsulation layer, using a camera to obtain an image of the product surface, identifying and judging the overlapping condition of the wiring terminal and the wiring electrode; if the two remain overlapping, it is considered to meet the requirements; if the two have been separated and no longer overlap, or the change in the overlapping shape exceeds a set range, it is considered that there is a deviation in the positioning of the resistance layer and the electrode layer, and a warning message is issued.

[0031] Compared with the prior art, the technical effects of the present invention are:

[0032] 1. Since the production of thick film heaters uses a multi-layer stacking process, the layer-by-layer retreat identification structure design proposed in the present invention can easily detect whether the number of printed layers is sufficient through human eyes or image recognition technology during the production process; this intuitive judgment method is more direct and efficient.

[0033] 2. Based on the layer-by-layer step-back identification structure design, the present invention can use the thickness gauge to easily measure the actual thickness of each layer of the structure; compared with the thickness measurement scheme of traditional technology, it avoids subjective speculation and can provide a more accurate judgment basis for adjusting process parameters.

[0034] 3. The present invention uses a separate resistor slurry to make a target in the resistor layer, which is used as a positioning basis when coating the electrode layer. Compared with the traditional technology of uniformly using the target on the substrate, the resistor layer and the electrode layer in the product of the present invention fit more closely, the alignment is more precise, the overlapping position relationship between the terminal and the wiring electrode is more stable, and the consistency of the final resistance value between batches of products is also better, which can significantly improve the stability of product quality.

[0035] 4. The present invention can detect the positioning accuracy of each coating in the thick film heater based on the layer-by-layer step-back identification structure, and can also identify the alignment of the terminal block with the edge of a specified layer, as well as the overlapping condition of the terminal block and the wiring electrode, individually or in combination. It can improve the positioning accuracy between layers from multiple directions, thereby further ensuring product quality, reducing the scrap rate of semi-finished products, and reducing overall costs while improving quality stability.

[0036] 3. The present invention combines a multi-point, multi-level alignment solution, which makes the debugging in the production process more efficient and accurate. By using each target and the edge lines in the layer-by-layer step-back recognition structure, the printing error range can be controlled more intuitively and accurately, and the number and thickness detection of each layer structure is also simpler. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of a thick film heater with a layer-by-layer step-back recognition structure and a resistance positioning target.

[0038] Figure 2 Schematic diagram of the evolution of the structure identified by step-by-step retreat.

[0039] Figure 3 An alternative approach for targeting.

[0040] The reference numerals in the figure are: substrate 1, multilayer structure 2, layer-by-layer step-back identification structure 3, first target 4, second target 5; wiring terminal 6; wiring electrode 7. DETAILED DESCRIPTION

[0041] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings.

[0042] like Figure 1 As shown, the thick film heater with a layer-by-layer stepped identification structure described in the present invention includes a substrate 1 and a multilayer structure 2. Among them, the substrate is used as the supporting body of the thick film heater, and can be a flat or cylindrical structure made of metal or heat-resistant plastic material. The multilayer structure 2 is located on the surface of the substrate, including an insulating dielectric layer, a resistor layer, an electrode layer and an encapsulation layer arranged in sequence from bottom to top, which are respectively formed by repeatedly coating and sintering operations of the corresponding slurries. In order to meet the thickness requirements, it is usually impossible to complete the processing of the insulating dielectric layer in one go, and multiple insulating dielectric layers need to be formed through multiple coating and sintering operations. In the example of the present invention, the insulating dielectric layer adopts a 4-layer design.

[0043] The multi-layer coating and sintering process of thick film heaters belongs to the prior art. The present invention focuses on proposing an innovative design of a layer-by-layer step-back identification structure and a resistance positioning target. The coating and sintering process involved still uses the prior art, so the specific implementation method of the multi-layer coating and sintering process will not be repeated.

[0044] The step-by-step step-back identification structure 3 of the present invention is located at the side edge of the multi-layer structure 2, and is formed by stacking the insulating dielectric layer, the resistor layer, the electrode layer and the local protruding parts of the encapsulation layer in a step-by-step step-back manner; each layer in the structure has the same edge shape and maintains a spacing according to a set size. As an optional solution, each layer in the step-by-step step-back identification structure 3 has straight edges that are parallel to each other and maintain the same spacing. Figure 1 As shown in , the straight edge can be perpendicular to the edge of the adjacent multi-layer structure; or, it can also be in the form of an oblique line or a curve with the same curvature.

[0045] A first target 4 is provided on the substrate 1 for positioning during the coating and printing operation. The first target 4 can be punched on the substrate 1, formed into a protrusion, coated with a high temperature resistant coating, etc., and its shape is as follows: Figure 3 As shown in Figure 1 In the example, the first target 4 and the step-by-step step-back identification structure 3 are located on the same side of the multilayer structure 2, the first target 4 is at the coating start position of the multilayer structure 2, and the step-by-step step-back identification structure 3 is at the coating end position of the multilayer structure 2.

[0046] In order to meet the needs of precise positioning and quality monitoring, the present invention also proposes a design concept for resistor positioning targets. That is, at least one second target 5 for positioning is formed in the resistor layer by coating and sintering, as well as at least two wiring terminals 6 for connecting the internal circuit of the resistor layer; optionally, at least one wiring terminal 6 is aligned with the edge of a certain insulating dielectric layer in the step-by-step step-back identification structure 3. Adaptively, at least two wiring electrodes 7 for connecting external circuits are formed in the electrode layer by coating and sintering; the wiring terminals 6 and the wiring electrodes 7 are arranged one-to-one, and the wiring terminals and wiring electrodes in each group are in contact with each other, and can be arranged in a cross-cross or right-angled manner. As a further optional scheme, the wiring terminals 6 and the wiring electrodes 7 have a total of multiple even groups, and each two groups are correspondingly connected to a conductive loop in the resistor layer, and multiple conductive loops can be used to achieve partitioned or multi-stage heating control.

[0047] The present invention further provides a method for processing the thick film heater, comprising:

[0048] A first target 4 is formed on the surface of the substrate 1, which is cleaned and dried for later use; an insulating dielectric slurry is coated on the surface of the substrate 1 with the first target 4 as a positioning reference, and an insulating dielectric layer is formed after sintering; the operation is repeated for multiple times so that the total thickness of the insulating dielectric layer after stacking meets the requirements; a conductive slurry is continuously coated on the surface of the insulating dielectric layer with the first target 4 as a positioning reference, and a resistor layer is formed after sintering; the pattern of the resistor layer includes a second target 5 and at least one conductive loop, and each conductive loop includes two wiring terminals 6; an electrode slurry is continuously coated on the surface of the resistor layer with the second target 5 as a positioning reference, and an electrode layer is formed after sintering; and an electrode slurry is continuously coated on the surface of the resistor layer with the second target 5 as a positioning reference, and an electrode layer is formed after sintering. The pattern of the electrode layer includes wiring electrodes 7 arranged one-to-one with the wiring terminals 6 in the resistor layer, and the wiring terminals 6 in each group are in contact with the wiring electrodes 7; the first target 4 is used as a positioning reference, and the insulating dielectric slurry is continuously coated on the surface of the electrode layer, and an encapsulation layer is formed after sintering; a plurality of window areas are reserved in the encapsulation layer, and each window area is arranged one-to-one with the wiring electrodes 7 in the electrode layer, so that the wiring electrodes 7 are exposed on the surface of the thick film heater; the edges of each insulating dielectric layer, resistor layer, electrode layer and encapsulation layer form a local protrusion at a set area, and retreat backwards while being stacked layer by layer to form a layer-by-layer retreat identification structure 3. The slurry coating operation can be optionally performed by screen printing. When coating and sintering to form the electrode layer, at least one wiring terminal 6 is aligned with the edge of an insulating dielectric layer in the layer-by-layer retreat identification structure 3.

[0049] Based on the design of the layer-by-layer step-back identification structure 3, the present invention can detect the thickness of each coating in the thick film heater, as follows: for the layer-by-layer step-back identification structure 3 in the thick film heater, a thickness gauge is used to measure the thickness of each step-back area in turn; the actual thickness of each layer structure is obtained by the calculation method of subtracting the thickness of adjacent step-back areas.

[0050] Furthermore, visual recognition can also be used to detect the positioning accuracy of each coating in the thick film heater based on the layer-by-layer step-back recognition structure, as follows: a camera is used to obtain an image of the layer-by-layer step-back recognition structure in the thick film heater, and the spacing between the edges of each step-back area is identified and determined; if the spacing value between adjacent edges is within a threshold range, it is considered to meet the requirements; if the spacing value between adjacent edges exceeds the threshold, it is considered that there is a deviation in the coating positioning, and a warning message is issued.

[0051] In addition, in the present invention, a camera can be used to obtain images of the wiring terminals in the resistance layer and the layer-by-layer retreat identification structure, and identify and judge the alignment of the wiring terminals with the edge of a specified layer; if the alignment distance value of the two is within the threshold range, it is considered to meet the requirements; if the alignment distance value of the two exceeds the threshold, it is considered that there is a deviation in the positioning of the resistance layer, and a warning message is issued.

[0052] Similarly, since the various levels of coating of thick film heaters are at the micron level, and the patterned parts of the resistor layer and electrode layer have a significant difference in visual effect from the insulating medium layer and the encapsulation layer due to their composition, the product quality of thick film heaters can be detected by image recognition even when they are covered. Specifically: After the preparation of the electrode layer or the encapsulation layer, the image of the product surface is obtained by a camera to identify and determine the overlapping status of the terminal and the wiring electrode; if the two remain overlapping, it is considered to meet the requirements; if the two have separated and no longer overlap, or the change in the overlapping shape exceeds the set range, it is considered that there is a deviation in the positioning of the resistor layer and the electrode layer, and a warning message is issued.

[0053] The technology of using a camera to obtain image information and further realizing image recognition, analysis and display results, and issuing warnings through a computer built-in program is used to realize product quality monitoring; this is a very mature existing public technology, and there are a large number of mature commercial complete sets of products. Therefore, the specific implementation process of the present invention will not be repeated.

[0054] It can be understood that, based on the human eye's extremely high sensitivity to the recognition of equidistant lines and vertical cross lines, manual recognition can also be used to assist in quality inspection during the production process. By manually selecting unqualified intermediate products in a timely manner, the production line process can be shortened and the production efficiency of the production line can be further improved. Therefore, even if the production line is not equipped with computer image monitoring equipment, basic quality monitoring can be performed by manual detection in the presence of the layer-by-layer retreat recognition structure of the present invention. It can be seen that the design of the present invention has a very broad application prospect.

Claims

1. A thick film heater with a layer-by-layer step-back recognition structure, characterized in that: The thick film heater includes: A substrate, serving as a supporting body of the thick film heater; The multilayer structure is located on the surface of the substrate, and includes an insulating dielectric layer, a resistor layer, an electrode layer and an encapsulation layer arranged in sequence from bottom to top, and is formed by repeatedly coating and sintering the corresponding slurries; The layer-by-layer stepped identification structure is located at the side edge of the multi-layer structure and is formed by stacking the local protruding parts of the insulating medium layer, the resistor layer, the electrode layer and the encapsulation layer in a layer-by-layer stepped manner; each layer in the structure has the same edge shape and maintains a spacing according to a set size.

2. The thick film heater according to claim 1, characterized in that In the layer-by-layer step-back identification structure, each layer has straight edges that are parallel to each other and maintain the same spacing.

3. The thick film heater according to claim 2, characterized in that In the layer-by-layer step-back identification structure, the straight edge of each layer is perpendicular to the edge of the adjacent multi-layer structure.

4. The thick film heater according to claim 1, characterized in that The substrate is a flat plate or cylindrical structure made of metal or heat-resistant plastic material.

5. The thick film heater according to claim 1, characterized in that The insulating medium layer has one or more layers.

6. The thick film heater according to claim 1, characterized in that A first target for positioning is provided on the substrate surface and is located on the same side of the multilayer structure as the layer-by-layer step-back recognition structure; the first target is located at the coating start position of the multilayer structure, and the layer-by-layer step-back recognition structure is located at the coating end position of the multilayer structure.

7. The thick film heater according to any one of claims 1 to 6, characterized in that: In the resistor layer, at least one second target for positioning and at least two wiring terminals for connecting the internal circuit of the resistor layer are formed by coating and sintering; in the electrode layer, at least two wiring electrodes for connecting the external circuit are formed by coating and sintering; the wiring terminals and wiring electrodes are arranged one by one, and the wiring terminals and wiring electrodes in each group are in contact with each other.

8. The thick film heater according to claim 7, characterized in that The wiring terminals and wiring electrodes have a total of a plurality of even groups, and every two groups are correspondingly connected to a conductive loop in the resistance layer, so as to realize zoned or multi-stage heating control.

9. The thick film heater according to claim 7, characterized in that The connection terminals and the connection electrodes are arranged in a cross-cross or right-angled manner.

10. The thick film heater according to claim 7, characterized in that At least one of the wiring terminals is aligned with an edge of an insulating medium layer in the layer-by-layer step-back identification structure.

11. A method for processing a thick film heater with a layer-by-layer step-back identification structure, characterized in that: include: Forming a first target on the surface of the substrate, cleaning and drying it for later use; Using the first target as a positioning reference, an insulating dielectric slurry is coated on the surface of the substrate, and an insulating dielectric layer is formed after sintering; Repeat this operation several times until the total thickness of the insulating dielectric layer after stacking meets the requirements; Using the first target as a positioning reference, the conductive paste is continuously coated on the surface of the insulating dielectric layer, and a resistance layer is formed after sintering; the pattern of the resistance layer includes the second target and at least one conductive loop, and each conductive loop includes two wiring terminals; Using the second target as a positioning reference, the electrode slurry is continuously coated on the surface of the resistor layer, and the electrode layer is formed after sintering; the pattern of the electrode layer includes wiring electrodes arranged one by one corresponding to the wiring terminals in the resistor layer, and the wiring terminals in each group are in contact with the wiring electrodes; Using the first target as a positioning reference, the insulating medium slurry is continuously coated on the surface of the electrode layer, and an encapsulation layer is formed after sintering; a plurality of window areas are reserved in the encapsulation layer, and each window area is arranged correspondingly to the wiring electrode in the electrode layer, so that the wiring electrode is exposed on the surface of the thick film heater; The edges of each insulating medium layer, resistance layer, electrode layer and encapsulation layer form a local protrusion at a set area, and retreat backwards while being stacked layer by layer to form a layer-by-layer retreat identification structure.

12. The method according to claim 11, characterized in that The slurry coating operation is carried out by screen printing.

13. The method according to claim 11, characterized in that When the electrode layer is formed by coating and sintering, the connection terminal is aligned with the edge of a certain insulating medium layer in the layer-by-layer stepped identification structure.

14. A method for detecting the thickness of each coating in a thick film heater based on a layer-by-layer step-back recognition structure, characterized in that: include: For the layer-by-layer stepped-back identification structure in the thick film heater, a thickness gauge is used to measure the thickness of each stepped-back area in turn; the actual thickness of each layer structure is obtained by the calculation method of subtracting the thickness of adjacent stepped-back areas.

15. A method for detecting the positioning accuracy of each coating in a thick film heater based on a layer-by-layer step-back recognition structure, characterized in that: include: The camera is used to obtain the image of the layer-by-layer step-back recognition structure in the thick film heater, and the spacing between the edges of each step-back area is identified and determined; if the spacing value between adjacent edges is within the threshold range, it is considered to meet the requirements; if the spacing value between adjacent edges exceeds the threshold, it is considered that there is a deviation in the coating positioning and a warning message is issued.

16. The method according to claim 15, characterized in that It further includes: using a camera to obtain images of the wiring terminals in the resistance layer and the layer-by-layer retreat identification structure, identifying and judging the alignment of the wiring terminals with the edge of a specified layer; if the alignment distance value between the two is within a threshold range, it is deemed to meet the requirements; if the alignment distance value between the two exceeds the threshold, it is deemed that there is a deviation in the positioning of the resistance layer, and a warning message is issued.

17. A method for detecting the quality of thick film heater products by image recognition, characterized in that: include: After the preparation of the electrode layer or encapsulation layer is completed, the camera is used to obtain an image of the product surface to identify and determine the overlapping status of the terminal block and the wiring electrode; if the two remain overlapping, it is considered to meet the requirements; if the two have been separated and no longer overlap, or the change in the overlapping shape exceeds the set range, it is considered that there is a deviation in the positioning of the resistance layer and the electrode layer, and a warning message is issued.

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