Performance optimization design method of thick film printing ceramic heater

Abstract

The invention discloses a performance optimization design method for a thick film printing ceramic heater, and relates to the technical field of ceramic heaters, and the method comprises the following steps: S1, collecting basic parameters for manufacturing the ceramic heater; s2, establishing an initial three-dimensional model of the ceramic heater and the internal thick film printed circuit layer; and S3, importing the established initial three-dimensional model of the ceramic heater and the internal thick film printed circuit layer into grid division software, dividing grids in the grid division software, and exporting a grid file according to a format required by used simulation software after the division is completed. The method is used for conducting numerical simulation on the surface temperature of the thick film printing ceramic heater, data such as the surface temperature distribution condition of the heater, the temperature rising speed and the printing thickness of a heating circuit can be conveniently and rapidly obtained, reference is provided for optimization of the internal heating circuit, and the product quality of the thick film printing ceramic heater can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic heaters, and particularly to a method for optimizing the performance design of a thick-film printed ceramic heater. Background Art

[0002] Ceramic heaters have obvious advantages over metal heaters in terms of heating uniformity, high-temperature stability, heating rate, etc. There are generally two ways to fabricate ceramic heaters: dry pressing and tape casting. The internal heating circuit of a ceramic heater fabricated by dry pressing is a heating wire that is pre-processed as needed, and then the heating wire is pressed into the ceramic during the dry pressing process. Compared with tape casting, dry pressing has the advantages of high production efficiency, simple process, and low cost. However, it is difficult to fabricate heaters with complex shapes and high precision requirements. For such high-performance heaters, tape casting is suitable. The internal heating circuit of a tape-cast ceramic heater is fabricated by screen printing a metal paste. Compared with dry pressing, it has higher precision, can adapt to ceramic heater products with complex shapes, and has good product quality and consistency. Therefore, tape-cast ceramic heaters are usually used in high-precision equipment, such as aluminum nitride ceramic heaters and silicon carbide ceramic heaters.

[0003] High-precision equipment has high requirements for the surface temperature uniformity and heating rate of ceramic heaters. Currently, most in the industry improve the temperature uniformity and heating rate of ceramic heaters by optimizing the heating circuit distribution, increasing the thermal conductivity of the ceramic, and thickening the ceramic heater. Optimizing the heating circuit distribution is the main means, but most in the industry mainly optimize through production experience, resulting in poor optimization effects, long optimization cycles, and high optimization costs. For metal heaters using uniform heating elements, the simulation means in the publicly disclosed patents have high limitations and are not applicable to the simulation and optimization design of high-temperature thick-film printed high-precision ceramic heaters. Moreover, it assumes that the heat source is a uniformly heating wire rather than a resistance heating, which has a certain error from the actual situation. At the same time, the adjustable and optimizable space of the heating element is much smaller than that of the screen-printed thick-film circuit. Therefore, a method for optimizing the performance design of a thick-film printed ceramic heater is proposed. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems in the prior art, and a method for optimizing the performance design of a thick-film printed ceramic heater is proposed.

[0005] A method for optimizing the performance design of a thick-film printed ceramic heater includes the following steps:

[0006] S1. Collect the basic parameters for fabricating the ceramic heater;

[0007] S2. Establish an initial three-dimensional model of the ceramic heater and the internal thick-film printed circuit layer;

[0008] S3. Import the initially established 3D model of the ceramic heater and the internal thick-film printed circuit layer into the meshing software, mesh in the meshing software, and export the mesh file in the format required by the simulation software used after completion of meshing;

[0009] S4. Set the material parameters of the ceramic heater and the internal thick-film printed circuit layer in the simulation software according to the material properties of the materials used;

[0010] S5. Set the initial conditions and boundary conditions of the simulation;

[0011] S6. Conduct simulation operations, and adjust the series-parallel form, wire diameter, circuit layout range and position, spacing, printing thickness, number of printing layers, and material parameters of the printed circuit layer according to the simulation results of the temperature field and resistance value until the difference between the maximum value and the minimum value of the temperature on the working surface of the ceramic heater is within the range of the design requirements;

[0012] S7. Export the 3D model of the thick-film printed circuit layer when the difference between the maximum value and the minimum value of the temperature on the working surface of the ceramic heater meets the design requirements to draw the die drawings for the production and manufacture of the ceramic heater.

[0013] Preferably, in the step S1, the basic parameters include the specific dimensions, working temperature, working voltage, actual working conditions of the ceramic heater, and the requirements for resistance, rated power, heating rate, and temperature uniformity, and also include the material parameters of the ceramic heater and the printing paste.

[0014] Preferably, in the step S2, the 3D modeling tools used are one or more software among Solidworks, CAD, and Creo.

[0015] Preferably, in the step S3, the temperature simulation software used is one or more software among LS-Dyna, Ansys, and ABAQUS.

[0016] Preferably, in the step S4, the material parameters include material type, specific heat capacity, density, thermal conductivity, and conductivity-temperature curve of the thick-film printed circuit layer material.

[0017] Preferably, in the step S5, the initial condition is the temperature initial condition, that is, the initial temperature value of the entire model before heating, and the boundary conditions include the convective heat transfer coefficient and boundary, ambient temperature, radiative heat transfer coefficient and boundary, input voltage and output voltage boundary.

[0018] Compared with the existing technology, the advantages of the present invention are as follows:

[0019] The present invention provides a numerical simulation method for numerically simulating the surface temperature of a thick-film printed ceramic heater, facilitating the rapid acquisition of data such as the surface temperature distribution, heating rate, and printing thickness of the heating circuit of the heater, providing a reference for the optimization of the internal heating circuit, and being conducive to improving the product quality of the thick-film printed ceramic heater. Description of the Drawings

[0020] Figure 1 It is a flowchart of the present invention.

[0021] Figure 2 It is a circuit model diagram before simulation optimization in the present invention.

[0022] Figure 3 It is a temperature contour map before circuit optimization in the present invention.

[0023] Figure 4 It is a circuit model diagram after multiple simulation optimizations and adjustments in the present invention.

[0024] Figure 5 It is a temperature contour map after circuit optimization in the present invention.

[0025] Figure 6 It is a measured temperature uniformity map of the product in the present invention. Detailed Embodiments

[0026] To make the technical means, creative features, achieved purposes, and functions of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0027] Refer to Figure 1 As shown, a performance optimization design method for a thick-film printed ceramic heater includes the following steps:

[0028] S1. Collect the basic parameters for manufacturing the ceramic heater;

[0029] S2. Establish an initial three-dimensional model of the ceramic heater and the internal thick-film printed circuit layer, and the ceramic heater and the internal thick-film printed circuit layer need to be constructed according to the physical size of 1:1;

[0030] S3. Import the established initial three-dimensional model of the ceramic heater and the internal thick-film printed circuit layer into the mesh generation software, and generate meshes in the mesh generation software. After completion, export the mesh file according to the required format of the simulation software used;

[0031] S4. Set the material parameters of the ceramic heater and the internal thick-film printed circuit layer in the simulation software according to the material properties of the materials used;

[0032] S5. Set the initial conditions and boundary conditions of the simulation;

[0033] S6. Conduct simulation operations, and adjust the series-parallel form, wire diameter, circuit layout range and position, spacing, printing thickness, number of printing layers, and material parameters of the printed circuit layer according to the simulation results of the temperature field and resistance value until the difference between the maximum and minimum temperatures (i.e., temperature uniformity) on the working surface of the ceramic heater is within the range of the design requirements. Generally, the maximum temperature difference is controlled within 2°C.

[0034] S7. Export the 3D model of the thick-film printed circuit layer when the difference between the maximum and minimum temperatures on the working surface of the ceramic heater meets the design requirements to draw the die drawings for the production and manufacture of the ceramic heater.

[0035] In the step S1, the basic parameters include the specific dimensions, operating temperature, operating voltage, actual working conditions of the ceramic heater, as well as the requirements for resistance, rated power, heating rate, and temperature uniformity, and also include the material parameters of the ceramic heater and the printing paste.

[0036] In the step S2, the 3D modeling tools used are one or more software among Solidworks, CAD, and Creo.

[0037] In the step S3, the temperature simulation software used is one or more software among LS-Dyna, Ansys, and ABAQUS.

[0038] In the step S4, the material parameters include material type, specific heat capacity, density, thermal conductivity, and conductivity-temperature curve of the thick-film printed circuit layer material.

[0039] In the step S5, the initial condition is the temperature initial condition, that is, the initial temperature value of the entire model before heating. The boundary conditions include the convective heat transfer coefficient and boundary, ambient temperature, radiative heat transfer coefficient and boundary, input voltage and output voltage boundary.

[0040] Embodiment

[0041] (1) Collect basic parameters: The size of the ceramic heater is 28*28*2.5 mm, with a single-zone double-layer printed parallel circuit inside. The thick-film printed circuit material is conductive tungsten paste, with a resistivity of 1.0E-6 Ω·m, a resistance temperature coefficient TCR = 4500, and a density of 19250 kg / m 3 , an elastic modulus E = 407 GPa, a Poisson's ratio μ = 0.284, a specific heat capacity C = 130 J / (K·kg), and a thermal conductivity of 164 W / (m·K); the heater material is aluminum nitride ceramic, with a density of 3260 kg / m 3 , an elastic modulus E = 300 GPa, a Poisson's ratio μ = 0.2, a specific heat capacity C = 780 J / (K·kg), and a thermal conductivity of 150 W / (m·K). The electrode wire material is kovar alloy, and the K-type thermocouple material is an alloy, mainly composed of Ni metal.

[0042] (2) According to the design experience, draw a preliminary internal thick-film printed circuit layer, and then establish an initial 3D model of the ceramic heater and the internal thick-film printed circuit layer: Use industrial software SolidWorks to perform 3D modeling on the ceramic heater with appropriate geometric simplification and the preliminarily designed internal thick-film printed circuit layer. The ceramic heater and the internal thick-film printed circuit layer need to be modeled at a 1:1 physical size, as Figure 2 shown.

[0043] (3) Import the established initial 3D model of the ceramic heater and the internal thick-film printed circuit layer into the mesh generation software Hypermesh, and generate structured meshes in Hypermesh. After completion, export the mesh file according to the format required by the simulation software used.

[0044] (4) Set the material parameters: According to the material properties of the materials used, set the material parameters of the ceramic heater and the internal thick-film printed circuit layer in the simulation software respectively.

[0045] (5) Set the initial conditions and boundary conditions of the simulation. The initial temperature and the initial ambient temperature are set to 299 K (about 26 °C), the ambient convective heat transfer coefficient is 15, the boundary radiation emissivity of the ceramic heater is 0.88. Assign a potential difference of 186 V to the positive and negative electrodes of the thick-film printed circuit, and set the current to flow only within the printed circuit. Input the conductivity-temperature curve and the voltage curve according to the temperature coefficient of resistance of the printed circuit material, so that the heater quickly heats up to the operating temperature and then stabilizes at the operating temperature.

[0046] (6) Perform simulation calculations. By comparing the heating rate of the preliminary simulation model with the required heating rate of the design, the required resistance value of the circuit can be roughly determined. The resistance can be mainly adjusted by adjusting the overall line width, printing thickness, and parallel connection of double-layer or multi-layer circuits. The temperature field obtained from the unoptimized circuit simulation is as Figure 3 shown. The maximum temperature difference on the working surface is about 5 °C. According to the temperature contour map, the temperature in the lower area where the heater electrode leads out is relatively low. The power density of the relatively low-temperature area can be increased by appropriately reducing the line spacing and the line width, so as to optimize the temperature uniformity. In addition, the temperature uniformity can also be improved by modifying the circuit layout method and adjusting the wiring range until the difference between the maximum and minimum temperatures (temperature uniformity) on the working surface of the ceramic heater is within the range of the design requirements, generally with the maximum temperature difference controlled within 2 °C.

[0047] (7) After adjusting the circuit multiple times and performing simulation optimization, the internal circuit model is as Figure 4 , and the obtained temperature contour map is as Figure 5As shown, the lowest temperature of the heater is 629.2 K, the highest temperature is 630.3 K, and the maximum temperature difference is 1.1 K, that is, the maximum temperature difference on the working surface is less than 2 °C, meeting the design requirements. The designed resistance is 20 Ω, and the heating rate at full power is 203 °C / s.

[0048] (8) Export the 3D model of the thick-film printed circuit layer that meets the requirements after optimization to draw the drawing of the screen printing stencil mold for the printing production of the circuit layer, and export other relevant data for the production of the ceramic heater.

[0049] (9) The measured temperature uniformity of the ceramic heater product made in (8) is controlled within a maximum temperature difference of 2.1 °C (when the working temperature is 350 °C, five temperature measurements are taken in the actual required working area according to the product technical requirements). The measured room temperature resistance value is 18.6 Ω, and the measured heating rate at full power is 209 °C / s. All performance indicators meet the expectations. Figure 6 As shown, the measured room temperature resistance value is 18.6 Ω, and the measured heating rate at full power is 209 °C / s. All performance indicators meet the expectations.

[0050] In summary, the performance optimization design method of a thick-film printed ceramic heater provided by the present invention provides a numerical simulation method for numerically simulating the surface temperature of the thick-film printed ceramic heater, facilitating the rapid acquisition of data such as the surface temperature distribution, heating rate, and printing thickness of the heating circuit of the heater, providing a reference for the optimization of the internal heating circuit, and changing the existing general method of relying on experience to complete the optimization of heating elements.

[0051] As is known by common technical knowledge, the present invention can be implemented by other embodiments without departing from its spirit or essential characteristics. Therefore, the above-disclosed embodiments are illustrative in all respects and not exclusive. All changes within the scope of the present invention or equivalent to the present invention are encompassed by the present invention.

Claims

1. A performance optimization design method for a thick film printed ceramic heater, characterized in that: The following steps are involved: S1. Collect basic parameters for making ceramic heaters; S2, establishing an initial three-dimensional model of the ceramic heater and the internal thick film printed circuit layer; S3, importing the established initial three-dimensional model of the ceramic heater and the internal thick film printed circuit layer into a meshing software, and meshing the model in the meshing software, and after the meshing is completed, exporting the mesh file according to the format required by the simulation software used; S4. According to the material properties of the materials used, the material parameters of the ceramic heater and the internal thick film printed circuit layer are set in the simulation software respectively; S5. Setting the initial conditions and boundary conditions of the simulation; S6. Perform simulation operations, and adjust the series-parallel form, wire diameter, circuit layout range and position, spacing, printing thickness, number of printing layers, and material parameters of the printed circuit layer according to the simulation results of the temperature field and the resistance value, until the difference between the maximum and minimum temperatures of the working surface of the ceramic heater is within the range of the design requirements; S7. Export the three-dimensional model of the thick film printed circuit layer when the difference between the maximum and minimum values ​​of the working surface temperature of the ceramic heater meets the design requirements and draw a mold drawing for the production of the ceramic heater.

2. The performance optimization design method of a thick film printed ceramic heater according to claim 1, characterized in that: In step S1, the basic parameters include the specific size, operating temperature, operating voltage, actual working conditions, and requirements for resistance, rated power, heating rate, and temperature uniformity of the ceramic heater, as well as the material parameters of the ceramic heater and the printing paste.

3. The performance optimization design method of a thick film printed ceramic heater according to claim 1, characterized in that: In step S2, the three-dimensional modeling tool used is one or more software of Solidworks, CAD, and Creo.

4. The performance optimization design method of a thick film printed ceramic heater according to claim 1, characterized in that: In step S3, the temperature simulation software used is one or more of LS-Dyna, Ansys, and ABAQUS.

5. The performance optimization design method of a thick film printed ceramic heater according to claim 1, characterized in that: In the step S4, the material parameters include material type, specific heat capacity, density, thermal conductivity, and conductivity-temperature curve of the thick film printed circuit layer material.

6. The performance optimization design method of a thick film printed ceramic heater according to claim 1, characterized in that: In step S5, the initial condition is the temperature initial condition, that is, the initial temperature value of the entire model before heating, and the boundary conditions include the convection heat transfer coefficient and boundary, ambient temperature, radiation heat transfer coefficient and boundary, input voltage and output voltage boundary.

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