Thick film heater with layer-by-layer retreating identification structure

Abstract

The utility model relates to the technology of electric heaters, and aims to provide a thick film heater with a layer-by-layer retreating identification structure. The thick film heater comprises a substrate used as a supporting body and a multi-layer structure located on the surface of the substrate. The insulating medium layer, the resistance layer, the electrode layer and the encapsulation layer are sequentially arranged from bottom to top and are formed by coating and sintering corresponding slurry for multiple times; the side edge of the multi-layer structure is provided with a layer-by-layer backstage identification structure, and the layer-by-layer backstage identification structure is formed by overlapping local protruding parts of an insulating medium layer, a resistance layer, an electrode layer and an encapsulation layer in a layer-by-layer backstage mode; all layers in the structure have the same edge shape, and the intervals are kept according to the set size. The layer-by-layer returning identification structure can be used for detecting whether the number of printing layers is enough or not by using a human eye or image identification technology in the production process, and the actual thickness of each layer structure in a product is measured by using a thickness gauge, so that a more accurate judgment basis is provided for adjusting process parameters.

Description

Technical Field

[0001] This utility model relates to electric heater technology, and in particular to a thick film heater with a layer-by-layer step-down identification structure. Background Technology

[0002] In the field of electric heater technology, the concept of thick film is mainly relative to thin film, referring to a film layer with a thickness of several micrometers to tens of micrometers formed on a substrate using printing and sintering technology. Thick film heating elements are produced by screen printing, sequentially printing insulating media, heating resistors, conductor materials, and protective media onto a heating element substrate, followed by high-temperature sintering. Stainless steel, with its excellent resistance to mechanical and thermal shock, moderate cost, and ease of processing, is an ideal substrate for high-power thick film circuits. Then, a paste with a specific resistivity (usually a metal oxide or other conductive material) is coated onto the substrate using screen printing or other methods, followed by high-temperature sintering to form a robust and durable resistive layer (the pattern of the resistive layer needs to be designed according to the product's functional requirements). Electrode layers and dielectric layers with matching patterns are then added according to the design requirements, enabling heating when power is applied. This technology, due to its advantages such as fast response time, high energy efficiency, and long service life, has wide applications in household appliances (such as water heaters), the automotive industry (e.g., for rearview mirror defrosting / fogging), medical equipment, and aerospace.

[0003] In the production process of thick-film heaters, the insulating dielectric layer is typically quite thick, making it impossible to complete in a single printing and sintering process. Therefore, the final thick-film heater product may have more than six layers. Product design imposes specific thickness requirements on each layer; excessive thinness can lead to insulation failure, unbalanced heating power, and reduced electrode stability, while excessive thickness results in significant raw material loss and insufficient heating power. However, due to the multiple printing and sintering processes, the layers fuse together through in-situ covering and high-temperature heating, preventing individual peeling. Therefore, current thickness measurement techniques can only infer the process control status of each layer by measuring the total thickness, making it difficult to confirm whether the processing of each layer individually meets the thickness requirements of the product design.

[0004] Furthermore, during the printing process of each layer, existing solutions typically use a target placed on the substrate, employing image recognition technology from a CCD automatic alignment system to locate the operating area for screen printing, aiming to achieve in-situ coverage of the multi-layer structure as much as possible. However, because the substrate undergoes repeated high-temperature sintering as the processing progresses, the target's color changes during this process, making it difficult to identify during image recognition. Some existing technologies use the target on the substrate during the first layer printing, with subsequent layers using the pattern from the previous layer as a target for positioning. However, this approach introduces cumulative errors, leading to inter-layer misalignment. The inability to achieve precise positioning is a very serious technical problem, especially critical for subsequent electrode layer printing. Because thick-film heaters have high requirements for temperature uniformity, resistance consistency becomes even more critical. Unclear identification or large positioning errors can lead to inaccurate alignment between the electrode and resistor layers, causing deviations in the length of the resistor tracks, ultimately resulting in unacceptable resistance consistency. In severe cases, misalignment between the electrode and resistor layers can even prevent the entire thick-film heater from forming a closed circuit, rendering it unusable.

[0005] Therefore, it is necessary to propose new solutions to address the aforementioned technical problems. Utility Model Content

[0006] The technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and provide a thick film heater with a layer-by-layer step-down identification structure and a resistance positioning target.

[0007] To solve the above-mentioned technical problems, the solution adopted by this utility model is:

[0008] A thick film heater with a layer-by-layer step-back identification structure is provided. The thick film heater includes: a substrate serving as a support body for the thick film heater; a multilayer structure located on the surface of the substrate, including an insulating dielectric layer, a resistive layer, an electrode layer, and an encapsulation layer arranged sequentially from bottom to top, each formed by repeated coating and sintering operations of its corresponding paste; and a layer-by-layer step-back identification structure located at the side edge of the multilayer structure, formed by stacking locally protruding portions of the insulating dielectric layer, resistive layer, electrode layer, and 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.

[0009] As a preferred embodiment of this utility model, 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 embodiment of this utility model, in the step-by-step 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 embodiment of this utility model, the substrate is a flat or cylindrical structure made of metal or heat-resistant plastic.

[0012] As a preferred embodiment of this utility model, 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 coating start position of the multilayer structure, and the layer-by-layer step-back identification structure is located at the coating end position of the multilayer structure.

[0014] As a preferred embodiment of this utility model, at least one second target for positioning and at least two terminals for connecting the internal circuit of the resistor layer are formed in the resistive layer by coating and sintering; at least two terminals for connecting external circuits are formed in the electrode layer by coating and sintering; the terminals and terminals are arranged in a one-to-one correspondence, and the terminals and terminals in each group are in contact with each other.

[0015] As a preferred embodiment of this utility model, the wiring terminals and wiring electrodes have multiple even groups, and each pair of groups is connected to a conductive circuit in the resistor layer to realize zoned or multi-level heating control.

[0016] As a preferred embodiment of this utility model, the wiring terminals and wiring electrodes are arranged in a cross or right-angle connection manner.

[0017] As a preferred embodiment of this utility model, at least one of the terminals is aligned with the edge of an insulating dielectric layer in the step-by-step step-back identification structure.

[0018] Compared with the prior art, the technical effects of this utility model are:

[0019] 1. Since the production of thick film heaters uses a multi-layer stacking process, the layer-by-layer step-back identification structure design proposed in this utility model can easily detect whether the number of printing layers is sufficient through human eyes or image recognition technology during the production process; this intuitive judgment method is more direct and efficient.

[0020] 2. Based on the layer-by-layer step-down identification structure design, the actual thickness of each layer in the product can be easily measured using a thickness gauge; compared with the traditional thickness measurement scheme, subjective guessing is avoided, and more accurate judgment basis can be provided for adjusting process parameters.

[0021] 3. In this invention, a target is created using a separate resistive paste within the resistive layer, which is then used as a positioning reference when coating the electrode layer. Compared to the traditional technique of using a target uniformly on the substrate, the resistive and electrode layers in this invention fit more tightly, are more precisely aligned, have a more stable overlap between the terminals and electrodes, and exhibit better consistency in resistance values ​​across batches, significantly improving product quality stability.

[0022] 4. In this utility model product, the positioning accuracy of each coating in the thick film heater can be detected based on the layer-by-layer step-back identification structure. It can also identify the alignment of the wiring terminal with the edge of a specified layer, as well as the overlap of the wiring terminal and the wiring electrode, either individually or in combination. This 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.

[0023] 3. The product design of this utility model incorporates a multi-point, multi-level alignment scheme, resulting in higher debugging efficiency and greater accuracy during the production process. By using various targets and layer-by-layer step-back identification of edge lines in the structure, the printing error range can be controlled more intuitively and accurately, while also simplifying the detection of the quantity and thickness of each layer. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a thick film heater with a layer-by-layer step-down identification structure and a resistance positioning target.

[0025] Figure 2 A schematic diagram illustrating the evolution of the step-by-step receding structure.

[0026] Figure 3 This is an optional solution for locating the target.

[0027] The attached figures are labeled as follows: 1. Substrate; 2. Multilayer structure; 3. Layer-by-layer step-back identification structure; 4. First target; 5. Second target; 6. Wiring terminal; 7. Wiring electrode. Detailed Implementation

[0028] The specific embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0029] like Figure 1As shown, the thick-film heater with a layer-by-layer step-down identification structure of this utility model includes a substrate 1 and a multilayer structure 2. The substrate serves as the support body of the thick-film heater and can be a flat or cylindrical structure made of metal or heat-resistant plastic. The multilayer structure 2 is located on the surface of the substrate and includes, from bottom to top, an insulating dielectric layer, a resistive layer, an electrode layer, and an encapsulation layer, each formed by repeated coating and sintering operations of its corresponding paste. To meet thickness requirements, the insulating dielectric layer cannot usually be processed in one step and requires multiple coating and sintering operations to form a multilayer insulating dielectric layer. In this example, a four-layer insulating dielectric layer design is used.

[0030] The multi-layer coating and sintering process of thick film heaters is existing technology. This utility model focuses on the innovative design of the layer-by-layer step-down identification structure and the resistance positioning target in the product. The coating and sintering process involved in the production process still uses existing technology, so it will not be described in detail.

[0031] The step-back identification structure 3 of this invention is located on the side edge of the multilayer structure 2. It is formed by stacking locally protruding portions of an insulating dielectric layer, a resistive layer, an electrode layer, and an encapsulation layer in a step-back manner. Each layer in this structure has the same edge shape and maintains a spacing according to a set size. Alternatively, each layer in the step-back identification structure 3 may have parallel straight edges that maintain the same spacing. Figure 1 As shown, the straight edge can be perpendicular to the edge of the adjacent multi-layer structure; or it can be a diagonal line or a curve with the same curvature.

[0032] A first target 4 is provided on the substrate 1 for positioning during the coating and printing operation. The first target 4 can be configured by drilling holes in the substrate 1, constructing protrusions, or coating with a high-temperature resistant coating, etc., and its shape is shown in the example below. Figure 3 As shown. In Figure 1 In the example, the first target 4 and the layer-by-layer step-back identification structure 3 are located on the same side of the multilayer structure 2. The first target 4 is located at the coating start position of the multilayer structure 2, and the layer-by-layer step-back identification structure 3 is located at the coating end position of the multilayer structure 2.

[0033] To enhance the accuracy of positioning and quality monitoring, this invention also proposes a design concept for a resistance positioning target. Specifically, at least one second target 5 for positioning and at least two terminals 6 for connecting to the internal circuitry of the resistance layer are formed in the resistance layer through a coating and sintering process. Optionally, at least one terminal 6 is aligned with the edge of an insulating dielectric layer in the step-by-step identification structure 3. Correspondingly, at least two electrodes 7 for connecting to external circuitry are formed in the electrode layer through a coating and sintering process. The terminals 6 and electrodes 7 are arranged in a one-to-one correspondence, and the terminals and electrodes within each group are in contact with each other, optionally arranged in a cross-shaped or right-angled configuration. As a further optional solution, the terminals 6 and electrodes 7 have multiple even groups, with each pair of groups correspondingly connected to a conductive loop in the resistance layer. These multiple conductive loops can be used to achieve zoned or multi-level heating control.

[0034] For ease of understanding, the processing procedure of this utility model product is described below:

[0035] First, a first target 4 is formed on the surface of substrate 1, and then cleaned and dried for later use. Using the first target 4 as a positioning reference, an insulating dielectric paste is coated on the surface of substrate 1, and after sintering, an insulating dielectric layer is formed. This operation is repeated multiple times to ensure that the total thickness of the stacked insulating dielectric layers meets the requirements. Using the first target 4 as a positioning reference, a conductive paste is further coated on the surface of the insulating dielectric layer, and after sintering, a resistive layer is formed. The pattern of the resistive layer includes a second target 5 and at least one conductive loop, each conductive loop including two terminals 6. Using the second target 5 as a positioning reference, an electrode paste is further coated on the surface of the resistive layer, and after sintering, an electrode layer is formed. The electrode layer pattern includes terminals 7 arranged one-to-one with terminals 6 in the resistor layer, and terminals 6 and terminals 7 in each group are in contact with each other. Using the first target 4 as a positioning reference, an insulating medium paste is applied to the surface of the electrode layer, and after sintering, an encapsulation layer is formed. Multiple window areas are retained in the encapsulation layer, and each window area is arranged one-to-one with the terminals 7 in the electrode layer, so that the terminals 7 are exposed on the surface of the thick film heater. The edges of each insulating medium layer, resistor layer, electrode layer and encapsulation layer form local protrusions at designated areas, which recede backward while being stacked layer by layer to form a step-back identification structure 3. The paste application operation can be performed by screen printing. When coating and sintering to form the electrode layer, at least one terminal 6 is aligned with the edge of an insulating medium layer in the step-back identification structure 3.

[0036] Based on the design of the layer-by-layer step-down identification structure 3, the thickness of each coating in the thick film heater can be detected, as follows: For the layer-by-layer step-down identification structure 3 in the thick film heater, the thickness of each step-down area is measured sequentially using a thickness gauge; the actual thickness of each layer is obtained by subtracting the thickness of adjacent step-down areas.

[0037] Furthermore, based on the layer-by-layer step-back identification structure, visual recognition can be used to detect the positioning accuracy of each coating in the thick film heater. Specifically, the image of the layer-by-layer step-back identification structure in the thick film heater is acquired by a camera, and the spacing between the edges of each step-back area is identified and judged. If the spacing between adjacent edges is within the threshold range, it is considered to meet the requirements. If the spacing between adjacent edges exceeds the threshold, it is considered that there is a deviation in the coating positioning, and a warning message is issued.

[0038] In addition, a camera can be used to acquire images of the terminals and the step-by-step identification structure in the resistor layer, identify and judge the alignment of the terminals with the edge of a specified layer; if the alignment distance is within the threshold range, it is considered to meet the requirements; if the alignment distance exceeds the threshold, it is considered that there is a deviation in the positioning of the resistor layer, and a warning message is issued.

[0039] Similarly, since the coatings of thick-film heaters are at the micron level, and the patterned portions in the resistive and electrode layers differ significantly in composition and visual appearance from the insulating dielectric and encapsulation layers, image recognition can be used to detect the product quality of thick-film heaters even when they are covered. Specifically: after the electrode or encapsulation layer is prepared, an image of the product surface is captured by a camera to identify and determine the overlap of the terminals and electrodes. If they remain overlapped, it is considered compliant; if they have separated and no longer overlap, or if the overlap shape changes beyond a set range, it is considered that there is a positioning deviation between the resistive and electrode layers, and a warning message is issued.

[0040] The technology of using cameras to acquire image information and then using computer-built-in programs to realize image recognition, analysis and display of results and issue warnings is used to achieve product quality monitoring. This is a very mature existing public technology, and there are already a large number of mature commercial complete products available, which can be selected according to the actual situation.

[0041] It is understandable that, given the human eye's high sensitivity to equidistant and perpendicularly intersecting lines, manual identification can be used to assist in quality inspection during production. By manually selecting defective intermediate products, production line processes can be shortened, further improving production efficiency. Therefore, even production lines without computer image monitoring equipment can perform basic quality control through manual inspection, provided the layer-by-layer identification structure is in place. Thus, the design described in this invention has a very broad range of applications.

Claims

1. A thick film heater with a layer-by-layer step-down identification structure, characterized in that, The thick film heater includes: The substrate serves as the support body for the thick film heater; The multilayer structure, located on the substrate surface, includes an insulating dielectric layer, a resistive layer, an electrode layer and an encapsulation layer arranged sequentially from bottom to top, each formed by repeated coating and sintering operations of its corresponding paste; The step-back identification structure, located on the side edge of a multi-layer structure, is formed by stacking locally protruding portions of an insulating dielectric layer, a resistive layer, an electrode layer, and an encapsulation layer in a step-back manner; each layer in this structure has the same edge shape and maintains a spacing according to a set size.

2. The thick film heater with a layer-by-layer step-down identification structure 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 with a layer-by-layer step-down identification structure according to claim 2, characterized in that, In the layer-by-layer step-back identification structure, the straight edges of each layer are perpendicular to the edges of the adjacent multi-layer structure.

4. The thick film heater with a layer-by-layer step-down identification structure according to claim 1, characterized in that, The substrate is a flat or cylindrical structure made of metal or heat-resistant plastic.

5. The thick film heater with a layer-by-layer step-down identification structure according to claim 1, characterized in that, The insulating dielectric layer has one or more layers.

6. The thick film heater with a layer-by-layer step-down identification structure 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 identification structure; the first target is located at the coating start position of the multilayer structure, and the layer-by-layer step-back identification structure is located at the coating end position of the multilayer structure.

7. The thick film heater with a layer-by-layer step-down identification structure according to any one of claims 1 to 6, characterized in that, In the resistive layer, at least one second target for positioning and at least two terminals for connecting the internal circuit of the resistive layer are formed by coating and sintering. In the electrode layer, at least two terminals for connecting external circuits are formed by coating and sintering. The terminals and terminals are arranged in a one-to-one correspondence, and the terminals and terminals in each group are in contact with each other.

8. The thick film heater with a layer-by-layer step-down identification structure according to claim 7, characterized in that, The terminals and electrodes have multiple pairs of arrays, with each pair of arrays corresponding to a conductive loop in the resistive layer, used to achieve zoned or multi-level heating control.

9. The thick film heater with a layer-by-layer step-down identification structure according to claim 7, characterized in that, The terminals and electrodes are arranged in a cross or right-angle connection manner.

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

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