A printing jig design method based on ultra-thin circuit board printing technology

Abstract

The application belongs to the technical field of printing, and particularly relates to a printing jig design method based on ultra-thin circuit board printing technology. The application aims to solve the problems that the existing jig design is difficult to adapt to the ultra-thin circuit board, the printing precision and yield are low, the design cycle is long and the like due to the fact that the ultra-thin circuit board is extremely thin and easy to deform and warp. The method comprises the following steps: obtaining geometric and mechanical parameters of the ultra-thin circuit board; establishing an accurate deformation mechanical model of the ultra-thin circuit board under printing composite load; predicting the deformation behavior based on model simulation; optimizing the jig structure layout, support scheme and material selection according to the simulation result; and optimizing the jig design. Through the above technology, the application can effectively prevent the deformation and warping of the ultra-thin circuit board, significantly improve the printing precision and yield, shorten the design cycle, reduce the production cost, and promote large-scale and efficient production.

Description

Technical Field

[0001] This invention belongs to the field of printed circuit board manufacturing technology, specifically relating to a method for designing a printing fixture based on ultra-thin circuit board printing technology. Background Technology

[0002] With the rapid development of electronic information technology, circuit boards, as the core carrier of various electronic products, face increasingly stringent requirements in terms of manufacturing processes and performance. Especially with the current trend of electronic products evolving towards miniaturization, high integration, and high reliability, the application of ultra-thin circuit boards is becoming increasingly widespread. Due to their significant thinness and flexibility, ultra-thin circuit boards have shown great potential in fields such as smart wearables, high-end medical equipment, and aerospace. However, their precision manufacturing process, particularly the printing stage, presents unprecedented challenges to accuracy and yield.

[0003] Ultra-thin circuit boards, due to their extremely low thickness, are highly susceptible to deformation and warping under external stress during the printing process, leading to increased printing misalignment and defects. Therefore, printing fixtures play a crucial role in the manufacturing of ultra-thin circuit boards. Their main functions are to precisely position the circuit board, provide stable support, and effectively prevent deformation to ensure printing accuracy and quality. However, existing fixture design methods are typically developed for circuit boards of conventional thickness, and their structural design, material selection, and mechanical analysis models are insufficient to fully adapt to the special physical characteristics and micron-level precision requirements of ultra-thin circuit boards.

[0004] Existing technologies for ultra-thin PCB printing fixture design have several shortcomings. Traditional design methods often lack the ability to accurately model and simulate the deformation behavior of ultra-thin PCBs under combined loads such as printing pressure and temperature changes, making it difficult to effectively predict and compensate for potential deformations. Furthermore, the selection of fixture materials and structural layout fail to fully consider the flexibility of ultra-thin boards, potentially introducing new stress concentrations or uneven support during the fixing process. In addition, the lack of automated design processes and optimization algorithms makes fixture design highly dependent on engineer experience, resulting in long design cycles, high iteration costs, and difficulty in ensuring consistency and optimal performance across different batches of fixtures, ultimately affecting printing yield and severely restricting the large-scale, efficient production of ultra-thin PCBs. Therefore, a printing fixture design method based on ultra-thin PCB printing technology is desired. Summary of the Invention

[0005] With the rapid development of electronic information technology, circuit boards, as the core carrier of various electronic products, face increasingly stringent manufacturing processes and performance requirements. Especially with the current trend of electronic products evolving towards miniaturization, high integration, and high reliability, the application of ultra-thin circuit boards is becoming increasingly widespread. Due to their significant thinness and flexibility, ultra-thin circuit boards have shown great potential in fields such as smart wearables, high-end medical devices, and aerospace. However, their precision manufacturing process, particularly the printing stage, presents unprecedented challenges to accuracy and yield. During the printing process, ultra-thin circuit boards, due to their extremely low thickness, are highly susceptible to deformation and warping under external stress, leading to increased printing misalignment and defects. Therefore, printing fixtures play a crucial role in the manufacturing of ultra-thin circuit boards. Their main functions are to accurately position the circuit board, provide stable support, and effectively prevent deformation to ensure printing accuracy and quality. Existing fixture design methods are typically developed for circuit boards of conventional thickness. Their structural design, material selection, and mechanical analysis models are insufficient to fully adapt to the special physical characteristics and micron-level precision requirements of ultra-thin circuit boards. Traditional design methods often lack the ability to accurately model and simulate the deformation behavior of ultra-thin circuit boards under combined loads such as printing pressure and temperature changes, making it difficult to effectively predict and compensate for potential deformations. Furthermore, the selection of fixture materials and structural layout often fail to fully consider the flexibility of ultra-thin boards, potentially introducing new stress concentrations or uneven support during the fixing process. In addition, the lack of automated design processes and optimization algorithms makes fixture design highly dependent on engineer experience, resulting in long design cycles, high iteration costs, and difficulty in ensuring consistency and optimal performance across different batches of fixtures. Ultimately, this affects printing yield and severely restricts the large-scale, efficient production of ultra-thin circuit boards.

[0006] To address the aforementioned technical problems, this application is proposed. Embodiments of this application provide a printing fixture design method based on ultra-thin circuit board printing technology. This method establishes a precise deformation mechanical model of the ultra-thin circuit board during the printing process, uses simulation analysis to predict its deformation behavior, and optimizes the structural layout, support scheme, and material selection of the printing fixture accordingly. Simultaneously, it introduces automated design processes and optimization algorithms. This overcomes the shortcomings of existing fixture design methods that cannot adapt to the special physical characteristics and high precision requirements of ultra-thin circuit boards, effectively preventing deformation and warping, improving printing accuracy and yield, shortening the design cycle, reducing production costs, and thus promoting the large-scale and efficient production of ultra-thin circuit boards.

[0007] According to one aspect of this application, a method for designing a printing fixture based on ultra-thin circuit board printing technology is provided, comprising:

[0008] Obtain the geometric and material mechanical parameters of the ultrathin circuit board to be designed for the printing fixture;

[0009] Establish a deformation mechanical model of ultrathin circuit boards under combined loads during the printing process;

[0010] Simulation analysis based on deformation mechanics model is used to predict the deformation behavior of ultrathin circuit boards.

[0011] Based on the simulation analysis results, the structural layout and support scheme of the printing fixture are designed, and the fixture material is selected.

[0012] The design of the printing fixture is optimized to meet the requirements of printing accuracy and yield.

[0013] According to a specific embodiment of this application, the geometric parameters and material mechanical parameters of the ultrathin circuit board adapted to the printing fixture to be designed are obtained, specifically including:

[0014] Obtain the thickness, length, width, and number of layers of the ultra-thin circuit board;

[0015] To obtain the elastic modulus, Poisson's ratio, coefficient of thermal expansion, and yield strength of the substrate and conductor materials used in ultra-thin circuit boards;

[0016] Obtaining the geometric and material mechanical parameters of ultra-thin circuit boards can be accomplished by consulting circuit board design drawings, material supplier datasheets, and conducting at least one of the following: physical performance tests.

[0017] According to a specific embodiment of this application, a deformation mechanical model of an ultra-thin circuit board under composite loads during the printing process is established, specifically including:

[0018] The ultrathin circuit board is discretized into finite element mesh elements, and corresponding material properties are defined for each mesh element.

[0019] Define the composite load that ultrathin circuit boards bear during the printing process. The composite load includes at least one of the following: printing squeegee pressure, screen tension, ambient temperature change, vacuum suction force, and fixture clamping force.

[0020] A finite element model is established that considers the nonlinear behavior, large deformation characteristics, and thermo-mechanical coupling effect of ultrathin circuit board materials. In the finite element model, a multi-scale mechanical model is further established to simulate the influence of microstructures such as wires and dielectric layers on macroscopic deformation behavior.

[0021] According to a specific embodiment of this application, simulation analysis is performed based on a deformation mechanics model to predict the deformation behavior of an ultrathin circuit board, specifically including:

[0022] Static analysis of the finite element model was performed using finite element analysis software to predict the displacement, stress, and strain distribution of the ultrathin circuit board under stable printing pressure.

[0023] The finite element analysis software was used to perform transient dynamic analysis on the finite element model to simulate the deformation response during dynamic processes such as the movement of the printing squeegee and temperature changes.

[0024] Buckling analysis was performed on the finite element model using finite element analysis software to assess the possibility of structural instability of the ultrathin circuit board under printing pressure.

[0025] Multi-condition prediction of the deformation behavior of ultra-thin circuit boards under different combinations of printing parameters, including different squeegee pressure, squeegee speed and printing temperature.

[0026] The simulation analysis results are output, including the maximum displacement of key areas, local warping, stress concentration areas, and the expected printing alignment error.

[0027] According to a specific embodiment of this application, based on simulation analysis results, the structural layout and support scheme of the printing fixture are designed, and the fixture material is selected, specifically including:

[0028] Based on the deformation characteristics determined by simulation analysis, the distribution of support points or support surfaces of the printing fixture is optimized to uniformly distribute the load borne by the ultra-thin circuit board and avoid stress concentration.

[0029] The clamping mechanism of the printing fixture is designed to use flexible clamping or vacuum adsorption to avoid physical damage to the ultra-thin circuit board or introduce new deformation.

[0030] The positioning mechanism of the printing fixture is designed, including high-precision positioning pins and edge clamping components, to ensure the precise position of the ultra-thin circuit board during the printing process.

[0031] The body material of the printing fixture is selected to have high rigidity, low coefficient of thermal expansion and excellent wear resistance. The body material includes high-strength aluminum alloy or engineering ceramics.

[0032] The material for the contact surface between the printing fixture and the ultra-thin circuit board is selected. The contact surface material is flexible, has a low coefficient of friction, and is antistatic. The contact surface material includes silicone rubber or polyurethane elastomer.

[0033] According to a specific embodiment of this application, the design of the printing fixture is optimized to meet the requirements of printing accuracy and yield, specifically including:

[0034] Set optimization goals, including minimizing printing deformation of ultra-thin circuit boards, minimizing printing alignment error, and maximizing printing yield.

[0035] The structure of the printing fixture is optimized by applying a topology optimization algorithm to reduce weight and optimize material distribution while maintaining the necessary stiffness.

[0036] The application of parameter optimization algorithms iteratively adjusts the geometric dimensions, support parameters, and material selection of the printing fixture, and finds the optimal combination of design parameters through repeated simulation analysis;

[0037] The mechanical modeling, deformation simulation, fixture structure design and optimization algorithm of ultra-thin circuit boards are integrated into the automated design platform to achieve parametric and rapid design iteration;

[0038] We conducted actual printing verification by prototyping sample fixtures, and provided feedback and further optimization of the fixture design based on the actual printing results.

[0039] Compared with existing technologies, this application provides a printing fixture design method based on ultra-thin circuit board printing technology. By obtaining detailed geometric and material mechanical parameters of the ultra-thin circuit board, it establishes an accurate deformation mechanics model considering composite loads, material nonlinearity, and thermo-mechanical coupling effects. Furthermore, multi-dimensional simulation analysis is performed using finite element analysis software to accurately predict the deformation behavior of the ultra-thin circuit board during the printing process. Based on this, the structural layout and support scheme of the printing fixture are systematically designed according to the simulation results, and the fixture materials are scientifically selected. In particular, by optimizing the distribution of support points, designing a flexible clamping mechanism, and selecting high-performance materials, the problem of easy deformation and warping of ultra-thin circuit boards during the printing process is effectively solved. This application also introduces topology optimization and parameter optimization algorithms and constructs an automated design platform, which greatly shortens the design cycle, reduces reliance on engineer experience, and ensures the consistency and optimal performance of the fixture design. Thus, this application can significantly improve the printing accuracy and yield of ultra-thin circuit boards, overcome the shortcomings of existing technologies in handling the special physical characteristics and high precision requirements of ultra-thin circuit boards, provide solid technical support and a brand-new solution for the large-scale and efficient production of ultra-thin circuit boards, and further promote the development of electronic manufacturing technology in the fields of miniaturization and high integration. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the overall technical solution architecture of the printing fixture design method based on ultra-thin circuit board printing technology proposed in this invention;

[0041] Figure 2 This is a schematic diagram of the core principle framework for modeling and simulation analysis of the deformation mechanics of ultra-thin circuit boards in this invention. Detailed Implementation

[0042] In the following description, specific terminology and structures are used to illustrate embodiments of the invention for ease of understanding. However, these descriptions are not intended to limit the invention, and those skilled in the art will understand that various modifications and substitutions can be made without departing from the spirit and scope of the invention. The accompanying drawings are for illustrative purposes only, are not drawn to scale, and should not be construed as limiting the invention.

[0043] Ultra-thin circuit board (PCB) printing technology plays a crucial role in the manufacturing of miniaturized electronic products. However, its inherent flexibility and fragility make it highly susceptible to deformation (such as warping and bending) during traditional printing processes, leading to a significant decline in printing quality. This manifests as misalignment, insufficient filling, or overflow of solder paste or ink, ultimately drastically reducing production yield and significantly increasing manufacturing costs. Existing printing fixture design methods primarily target rigid conventional PCBs, failing to fully consider the complex mechanical behavior of ultra-thin PCBs under the influence of multiple factors such as printing pressure, temperature variations, and their own gravity. Consequently, fixture support schemes are insufficient to effectively suppress deformation, and their design process often relies on experience and repeated trial and error, resulting in long processing times and low efficiency, which cannot meet the stringent requirements of high precision and high efficiency in modern electronics manufacturing. These issues collectively constitute a pressing technical challenge in the field of ultra-thin PCB printing technology.

[0044] To address the aforementioned technical problems, this application proposes a printing fixture design method based on ultra-thin circuit board printing technology. By introducing sophisticated ultra-thin circuit board deformation mechanics modeling and simulation analysis technology, it systematically evaluates the dynamic mechanical response of ultra-thin circuit boards during the printing process and intelligently optimizes the fixture's support structure and fixing scheme based on simulation results. This allows for precise offsetting or significant suppression of circuit board deformation. This method transforms traditional experience-based design into data-driven scientific design, achieving quantitative control over the distribution of fixture support points, support mechanical parameters, and material selection. This effectively improves the accuracy and yield of ultra-thin circuit board printing, providing a solid technical guarantee for the manufacturing of high-density, miniaturized electronic products.

[0045] In particular, this application proposes a method for designing printing fixtures based on ultra-thin circuit board printing technology. Figure 1 This is a schematic diagram of the overall technical solution architecture of the printing fixture design method based on ultra-thin circuit board printing technology according to an embodiment of this application. Figure 2 This is a schematic diagram illustrating the core principle framework of ultra-thin circuit board deformation mechanics modeling and simulation analysis according to embodiments of this application. Figure 1 and Figure 2 As shown, the printing fixture design method based on ultra-thin circuit board printing technology according to an embodiment of this application includes:

[0046] S110, obtain the design parameters and printing process requirements for ultra-thin circuit boards;

[0047] S120, constructing a deformation mechanical model for ultra-thin circuit boards;

[0048] S130, perform deformation mechanics simulation analysis to predict printing deformation;

[0049] S140, Design the fixture support structure and fixing scheme based on the deformation analysis results;

[0050] S150, for fixture design verification and optimization.

[0051] In the aforementioned method for designing printing fixtures based on ultra-thin circuit board printing technology, step S110 involves obtaining the design parameters and printing process requirements of the ultra-thin circuit board. This step aims to provide comprehensive foundational data for subsequent deformation mechanics modeling and simulation analysis, ensuring that the designed fixture accurately meets the manufacturing requirements of a specific ultra-thin circuit board and adapts to actual printing process conditions. Specifically, obtaining the ultra-thin circuit board design parameters includes, but is not limited to, the following data: circuit board geometry (length, width, and crucially, thickness, typically less than 0.2 mm), circuit board material properties (e.g., elastic modulus, Poisson's ratio, coefficient of thermal expansion of the substrate material, and mechanical and thermal parameters of the copper layers), layer stack information (thickness and arrangement order of each layer), and the location and size distribution of key pads. These parameters directly determine the mechanical response characteristics of the circuit board under stress and heat. Obtaining printing process requirements covers all key process variables involved in the printing process, such as the type of solder paste or ink used (its viscosity, thixotropy, and other rheological properties), stencil thickness, squeegee pressure, squeegee speed, printing ambient temperature, reflow soldering temperature profile, and ambient humidity. These process parameters will serve as external loads and boundary conditions in the mechanical model.

[0052] Specifically, obtaining design parameters and printing process requirements for ultra-thin circuit boards involves multiple data sources and acquisition mechanisms. Circuit board geometry and stack-up information are typically obtained from computer-aided design (CAD) files or exported data from circuit board design software; for example, detailed stack-up information and geometric topology can be extracted by parsing ODB++ format files. Circuit board material properties are derived from material supplier datasheets or obtained through laboratory testing (e.g., tensile tests, dynamic thermomechanical analysis), with accurate values ​​of elastic modulus and Poisson's ratio being crucial for predicting deformation. Pad location and size information are extracted directly from circuit board routing design documents. Printing process requirements are obtained through communication with the production department, reviewing process specifications, or from existing printing equipment parameter settings. To ensure data accuracy and consistency, data verification mechanisms must be introduced during the acquisition process, such as checking the legality range of acquired parameters, standardizing units, and cross-referencing between different data sources to identify and correct potential data errors or inconsistencies. For example, if the circuit board thickness data exceeds the typical range for ultra-thin circuit boards (e.g., less than 0.05 mm or more than 0.2 mm), an anomaly warning may be triggered, prompting further verification. All acquired parameters will be structured and stored in the design parameter database for subsequent modeling and simulation modules to use. Their physical or logical meanings will be clearly labeled, such as "elastic modulus, unit: gigapascal (GPa)" and "scraper pressure, unit: pascal (Pa)".

[0053] In the aforementioned printing fixture design method based on ultra-thin circuit board printing technology, step S120 involves constructing a deformation mechanics model for the ultra-thin circuit board. It should be understood that constructing this model aims to abstract the physical entity of the ultra-thin circuit board and its stress state during the printing process into a mathematical physical model, thereby enabling quantitative analysis and prediction of its deformation behavior. Due to its extremely small thickness, the mechanical behavior of ultra-thin circuit boards differs significantly from that of traditional thick boards, making it more suitable for description using thin-plate or ultra-thin-shell theories. Specifically, this step, based on the obtained circuit board design parameters and printing process requirements, establishes a mathematical model that accurately reflects the mechanical response of the circuit board under various loads. This model not only considers the material heterogeneity of the circuit board (e.g., the composite structure of the dielectric substrate and copper foil), but also its anisotropy and the thermal expansion effect during printing and heating processes.

[0054] Specifically, constructing a deformation mechanical model for ultrathin circuit boards mainly includes the following sub-steps:

[0055] First, a suitable mechanical theory model is selected. Given the characteristics of ultra-thin circuit boards, a shear deformation plate model based on Mindlin-Reissner theory or the more simplified but computationally efficient Kirchhoff thin plate theory is typically used for modeling.

[0056] The Mindlin-Reissner theory considers the transverse shear deformation effect of the board and is more suitable for ultra-thin circuit boards with a small thickness-to-planar-dimension ratio but where shear deformation cannot be ignored. Its stress-strain relationship and displacement field function can more accurately describe the actual situation. In contrast, the Kirchhoff thin-plate theory assumes zero transverse shear strain and is suitable for extremely thin circuit boards, but may have deviations in high stress concentration areas. The choice of model depends on the accurate thickness of the circuit board and the desired level of accuracy.

[0057] Secondly, the constitutive relations of the circuit board materials need to be defined. Circuit boards are typically composed of multilayer composite materials, including an epoxy resin substrate, glass fiber reinforcement, and copper foil. Therefore, it is necessary to establish the equivalent mechanical parameters or layered material models of the composite materials. For each layer, the elastic modulus, Poisson's ratio, shear modulus, and coefficient of thermal expansion obtained in step S110 need to be input. In some cases, if the circuit board material exhibits significant nonlinear elastic, plastic, or creep behavior, a more complex nonlinear constitutive model needs to be introduced.

[0058] Then, boundary conditions and load conditions are applied. Based on the printing process requirements obtained in S110, the actual stress conditions during the printing process are transformed into loads in the model. This includes:

[0059] Scraper pressure load: The vertical pressure exerted on the solder pad area by the scraper as it slides above the stencil. This pressure distribution is usually non-uniform and can be approximated as a uniformly distributed load over a specific area, or its dynamic distribution can be calculated using a more accurate fluid dynamics model. Circuit board self-weight load: Although ultra-thin circuit boards are lightweight, their self-weight can still cause slight deformations when they are large, especially in unsupported areas.

[0060] Thermal load: Changes in the printing environment temperature and the temperature gradient during the subsequent reflow soldering process may cause differential thermal expansion of the circuit board, resulting in thermal stress and thermal deformation.

[0061] Initial support conditions: Before designing the fixture, we can assume the initial contact or ideal boundary conditions such as simply supported or fixed support of the circuit board on the printing table to provide a benchmark for subsequent evaluation of free deformation.

[0062] Aerodynamic loads: In some high-speed printing or cleanroom environments, airflow may also exert a small force on the circuit board, but this is usually negligible.

[0063] For example, the deflection w(x,y) of a rectangular thin plate subjected to a uniformly distributed pressure load q under simply supported boundary conditions can be described by the following elastic thin plate deflection equation:

[0064]

[0065] Here, w is an unknown function representing the displacement of the thin plate in the direction perpendicular to its plane, i.e., deflection. It is a function of the position coordinates x and y, and w(x,y) describes the vertical displacement of every point on the thin plate. These are the fourth-order partial derivatives of w with respect to x and y. They represent the rates of change of the rate of change of the deflection w in the x and y directions, respectively. q(x,y) is the distributed load, representing the force acting on a unit area of ​​the thin plate. D is the bending stiffness, calculated using the following formula:

[0066]

[0067] Where E is the elastic modulus of the material, h is the thickness of the circuit board, and v is Poisson's ratio. This equation describes the deformation behavior of a thin board under vertical load. The bending stiffness D directly reflects the circuit board's ability to resist bending deformation and is proportional to the material properties and the cube of its thickness, highlighting the significant impact of the thickness on the mechanical properties of ultra-thin circuit boards. By solving this partial differential equation, the displacement field of the circuit board under specific loads and boundary conditions can be obtained, thus quantifying its deformation degree. This model forms the basis for subsequent simulation analysis and provides a theoretical foundation for identifying deformation hotspots.

[0068] In the aforementioned design method for printing fixtures based on ultra-thin circuit board printing technology, step S130 involves performing deformation mechanics simulation analysis to predict printing deformation. This step aims to utilize the aforementioned constructed mechanical model to simulate the actual deformation of the circuit board under various loads and boundary conditions during the printing process using numerical calculation methods. This quantifies the degree of deformation, identifies deformation areas, and assesses deformation risks. Accurate deformation prediction provides data support for fixture design, avoiding the blind spots inherent in traditional experience-based design.

[0069] Specifically, step S130 involves performing deformation mechanics simulation analysis to predict printing deformation, including:

[0070] S131, Define simulation boundary conditions and load parameters;

[0071] S132, Perform finite element analysis to obtain deformation data.

[0072] Specifically, step S131 defines the simulation boundary conditions and load parameters. This step, as you can understand it, transforms the actual printing process requirements obtained in S110 and the abstract loads and boundary conditions in the mechanical model constructed in S120 into quantifiable inputs that the simulation software can recognize. Its purpose is to ensure a high degree of consistency between the simulation scenario and the actual printing environment, thereby improving the accuracy of the prediction results. Specifically, this step refines the following parameters:

[0073] First, the geometric model is imported and meshed. The CAD geometric model of the ultra-thin circuit board is imported into the simulation analysis software, and a high-quality mesh is generated. Given the thinness and intricate structure of the circuit board (such as solder pads), an appropriate mesh type (e.g., shell elements, 3D solid elements) is required, ensuring that the mesh density is sufficiently fine in critical areas (such as solder pad areas and high stress gradient regions) to accurately capture local deformations. The quality of the mesh generation directly affects the convergence and accuracy of the simulation results.

[0074] Secondly, material properties are precisely applied. Based on the elastic modulus, Poisson's ratio, shear modulus, density, and coefficient of thermal expansion of each layer of material obtained from S110, these values ​​are precisely assigned to the corresponding mesh elements, and the laminate properties of the composite material are taken into account, such as defining the elastic tensor of anisotropic materials.

[0075] Then, set the specific load parameters.

[0076] Scraper pressure distribution: The scraper pressure value (e.g., 0.2 to 0.5 MPa) is mapped to the circuit board surface area corresponding to the stencil opening. A uniform pressure or a dynamically changing pressure profile can be applied based on the contact model between the scraper and the stencil. If the scraper's elasticity is considered, the pressure distribution may not be a simple uniform distribution.

[0077] Temperature load: If there are significant temperature changes or gradients in the printing environment or reflow process, a temperature field needs to be defined. This can be applied through a preset temperature profile or coupled with thermal simulation results. For example, the thermal expansion effect of a circuit board rising from room temperature to printing temperature (e.g., from 25 degrees Celsius to 30 degrees Celsius) or reflow peak temperature (e.g., 240 degrees Celsius).

[0078] Gravity load: The force applied to the circuit board itself.

[0079] Finally, define the boundary conditions.

[0080] Initial support conditions: In the absence of a fixture, it is typically assumed that the circuit board is placed on a flat printing table, which can be simulated by applying fixed constraints or elastic supports to the bottom edge or certain areas. For example, the support function of the pad can be simulated by setting certain nodes on the edge of the circuit board to have zero displacement or applying elastic supports.

[0081] Symmetrical boundary conditions: If the circuit board has geometric and load symmetry, symmetric boundary conditions can be used to simplify the calculation model and reduce the amount of calculation.

[0082] To ensure the correctness of the simulation input, all defined boundary conditions and load parameters need to be visually checked and logically verified. For example, this includes checking whether the pressure direction and constraint positions meet expectations, and whether the numerical values ​​are within a physically reasonable range. Specifically, in step S132, finite element analysis is performed to obtain deformation data. It should be understood that finite element analysis, as a powerful numerical computation method, aims to accurately solve the deformation response of the circuit board under the loads and boundary conditions defined in step S131 by discretizing a complex continuum into a finite number of elements and using unknowns at the nodes (such as displacement and temperature) to approximate the true solution. Specifically, this step includes the following detailed procedures:

[0083] First, preprocessing and model building. Import the aforementioned geometric model, mesh it, and set material properties and load boundary conditions in professional finite element analysis software (e.g., Ansys, Abaqus, or MSCMarc). This generates a complete finite element model file.

[0084] Secondly, solver configuration and selection. A suitable finite element solver is selected based on the complexity of the deformation mechanics model (e.g., linear or nonlinear, static or transient). For deformation prediction of ultra-thin circuit boards, static linear structural analysis or analysis modes considering geometric nonlinearity are typically used. If the dynamic effect of the squeegee during printing is considered, transient dynamic analysis may be necessary. The solver calculates the displacement of nodes by establishing and solving a large system of sparse matrix equations. Commonly used solution algorithms include direct methods (e.g., Cholesky decomposition) and iterative methods (e.g., the conjugate gradient method).

[0085] Then, the solution process is executed. The finite element solver is started for calculation. During the calculation, the system will monitor convergence; for example, for iterative solvers, it will check whether the residual norm has reached the preset convergence criterion. If non-convergence or calculation interruption occurs, the model settings, mesh quality, loads, and boundary conditions need to be checked for rationality.

[0086] Finally, post-processing and result extraction. After solving the problem, the obtained raw simulation results are post-processed. This includes: displacement field visualization: generating displacement contour maps of the circuit board in the X, Y, and Z directions, visually displaying the overall deformation trend and the area of ​​maximum deformation of the circuit board. Special attention is paid to the Z-axis displacement (deflection), as it directly affects printing accuracy.

[0087] Stress and strain distribution: Displays a contour map of stress (e.g., Von Mises stress, principal stresses) and strain distribution within the circuit board. High-stress areas may indicate potential material failure risks or deformation hotspots.

[0088] Deformation data extraction: Extracting key data from simulation results, such as:

[0089] Maximum deflection value and its location: Identify the point on the circuit board that deviates the most from the original plane.

[0090] Relative displacement of each pad area: Calculate the relative height difference and planar displacement within the same pad or between different pads. These are key indicators that directly affect printing accuracy.

[0091] Deformation gradient: Analyze the rate of deformation change with location; high gradient regions may require denser support.

[0092] All extracted deformation data will be stored in a structured format (e.g., node numbers, coordinates, displacement vectors), such as as a text file, CSV file, or a specific binary data file, for use in the subsequent fixture design step S140. It should be understood that obtaining deformation data provides a quantitative basis for selecting fixture support points and determining support mechanical parameters, and is a core step in achieving precision fixture design.

[0093] In the above-described printing fixture design method based on ultra-thin circuit board printing technology, step S140 involves designing the fixture support structure and fixing scheme based on the deformation analysis results. It should be understood that this step is the core of the invention; its goal is to systematically design a fixture that can effectively counteract, suppress, or compensate for the deformation of the ultra-thin circuit board during the printing process, based on the precise deformation data obtained in step S130. This design method transforms traditional experience-based design into a data-driven optimization process, thereby ensuring that the fixture can provide optimal support and fixation for the circuit board, significantly improving printing accuracy and product yield.

[0094] Specifically, step S140 involves designing the fixture support structure and fixing scheme based on the deformation analysis results, including:

[0095] S141, Determine the distribution of fixture support points and support mechanical parameters;

[0096] S142, Design the overall structure and auxiliary functional modules of the fixture.

[0097] Specifically, step S141 involves determining the distribution and mechanical parameters of the fixture's support points. This step aims to accurately identify and configure the critical support locations where the fixture contacts the ultra-thin circuit board, and to set the required mechanical properties for each support point to maximize the suppression of circuit board deformation. The rationality of the distribution and mechanical parameters of the support points directly determines the performance of the fixture. Specifically, step S141, determining the distribution and mechanical parameters of the fixture's support points, includes:

[0098] S1411, Determine the initial support point based on deformation hotspot identification;

[0099] S1412, optimize the layout and number of support points;

[0100] S1413, Determine the support material and support morphology.

[0101] Specifically, step S1411 involves determining initial support points based on deformation hotspot identification. It should be understood that the purpose of this step is to utilize the circuit board deformation simulation results obtained in step S130 to accurately identify the areas on the circuit board with the most significant deformation and the greatest impact on printing quality, and to prioritize these areas as the initial support points for the fixture. In this way, the fixture's support design can focus on addressing the most vulnerable and easily deformed areas of the circuit board, thereby achieving precise suppression of deformation. Specifically, the deformation hotspot identification process includes the following aspects:

[0102] First, the maximum deflection points are identified. In the Z-axis displacement contour map of the circuit board acquired in S132, all points with local or global maximum deflection are identified. These points are typically the areas where the circuit board first bends or warps under printing pressure; applying support to these points can directly reduce overall deformation.

[0103] Secondly, high stress concentration areas are identified. The stress distribution map obtained from S132 (e.g., Von Mises stress or principal stresses) is analyzed to identify stress concentration areas. Although high stress itself does not directly indicate deformation, it is often accompanied by large strain and is a potential area for material failure; supporting these areas helps to disperse the stress.

[0104] Next, assess the deformation of critical pad areas. Focus on examining deformation associated with pad areas, especially large pads, dense pad arrays, or areas containing pins of precision devices. If these areas have relative displacements or height differences that exceed tolerances, their surroundings or interiors should be used as support points.

[0105] Finally, edge and corner deformation must be considered. The edges and corners of ultra-thin circuit boards are prone to warping due to variations in constraints. Therefore, initial support points should also be considered in these areas.

[0106] The identified set of deformation hotspots will serve as candidate support points. Each hotspot includes its three-dimensional coordinates and corresponding deformation characteristic values ​​(e.g., maximum deflection value, stress value). The output of this step is an initial, prioritized list of support point coordinates, providing input for subsequent support point optimization.

[0107] Specifically, step S1412 optimizes the layout and number of support points. It should be understood that after determining the initial support points, the goal of this step is to use a systematic optimization algorithm to adjust the positions of the support points, determine the final number of support points, and their spacing, in order to minimize interference with the circuit board printing operation and consider manufacturing costs while meeting the deformation suppression objective. The optimized support point layout should enable the circuit board to maintain optimal flatness during the printing process.

[0108] Specifically, step S1412 optimizes the layout and number of support points, including:

[0109] S1412-1, Construct the influence matrix of support point distribution;

[0110] S1412-2, Calculate the stability index of the support point distribution;

[0111] S1412-3, Adjust the position of the support point based on the stability index.

[0112] Specifically, step S1412-1 involves constructing the influence matrix of the support point distribution. This step aims to quantify the influence of a single support point on the overall deformation behavior of the circuit board, as well as the interaction between different support points. By establishing this influence matrix, the impact of adjusting the position or mechanical parameters of a support point on the deformation of the entire circuit board can be more effectively evaluated, thus providing crucial sensitivity information for the optimization algorithm. Specifically, the construction of the influence matrix involves the following aspects: First, defining the influence coefficient. For each grid node i (or critical pad area) on the circuit board, and for each candidate support point j, an influence coefficient C is defined. ij This coefficient can be expressed as: the change in deflection of node i when a unit support force is applied at support point j; or, the change in deflection of node i when support point j undergoes a unit displacement. The influence coefficient can be calculated by applying a disturbance individually to each support point in the mechanical model constructed in S120 and obtaining the response using finite element analysis (S132).

[0113] Secondly, construct the matrix. Include all influence coefficients C. ij Organized into a matrix C, where rows represent the nodes under test on the circuit board and columns represent candidate support points. This matrix reflects the complex coupling relationship between the support points and the deformation of the circuit board.

[0114] Next, consider interactions. If multiple support points exist simultaneously, they may interact with each other; for example, an increase in the stiffness of one support point may affect the effective range of neighboring support points. In more complex scenarios, the influence matrix can consider nonlinear or coupling effects.

[0115] For example, let N be the number of critical nodes (or deformation hotspots) on the circuit board, and M be the number of candidate support points. For each critical node i, its initial deflection without fixture support is w. i,0 When a force F is applied at the support point j j At that time, the change in deflection at node i can be expressed as K. ij F j K ijLet be the coefficient of influence of support point j on the deflection of node i. Then, the total deflection w of node i under the fixture support... i,0 It can be represented as:

[0116]

[0117] If we express the deflection and support force of all key nodes in vector form, then we have:

[0118] w = w0 - KF

[0119] Where w is the final nodal deflection vector, w0 is the initial deflection vector, F is the support force vector, and K is the support point distribution influence matrix. It should be understood that the elements K of this matrix K... ij The effect of applying a unit force at support point j on the deflection of node i is quantified. This value is typically obtained by applying a unit load in a finite element model and calculating the response. This matrix provides optimization algorithms with information on the circuit board's sensitivity to changes in support points, enabling the optimization process to efficiently find the optimal support point configuration.

[0120] Specifically, step S1412-2 calculates the stability index of the support point distribution. It should be understood that the stability index is a key performance parameter for quantifying the effectiveness of the current support point layout. Its purpose is to comprehensively evaluate the overall flatness of the circuit board, the level of residual deformation, and its ability to resist external disturbances under fixture support. This index will serve as the objective function or constraint condition for subsequent support point optimization algorithms. Specifically, the calculation of the stability index covers the following aspects:

[0121] First, residual deformation indices. Based on the deflection equation defined in S1412-1, the residual Z-axis displacement of each key node (or all grid nodes) of the circuit board is calculated under the current support point layout. This can be quantified in several ways:

[0122] Maximum residual deflection: The goal is to minimize this value.

[0123] Mean square residual deflection: Reflecting the overall flatness, the goal is to minimize this value.

[0124] Critical area deformation difference: For a specific pad or device area, calculate the maximum height difference within it, with the goal of making it less than the preset tolerance.

[0125] Secondly, the stiffness matching index. This assesses the degree of matching between the overall stiffness of the fixture support points and the local stiffness of the circuit board. Insufficiently soft support may lead to localized deformation, while excessively stiff support may introduce new stress concentrations. This index measures the adaptability of the support system to the deformation modes of the circuit board.

[0126] Next, the contact pressure uniformity index is evaluated. If the support points are elastic supports, the contact pressure distribution between each support point and the circuit board is assessed. Overly concentrated pressure may damage the circuit board, while uneven pressure distribution may lead to localized warping. Finally, the robustness index for disturbance resistance is evaluated. The robustness of the current support point layout is assessed by simulating the impact of minor external disturbances (e.g., squeegee pressure fluctuations during printing, circuit board placement errors) on circuit board deformation.

[0127] For example, a commonly used stability index (or objective function J) can be defined as the weighted sum of the mean square residual deflection and the uniformity of the support force in all critical areas of the circuit board, expressed as:

[0128]

[0129] Where α and β are weighting coefficients, N is the number of key nodes, M is the number of support points, and w i F is the residual deflection of node i. j It is the supporting force of the j-th support point. This is the average value of all support forces. It should be understood that the left-hand side of the formula aims to minimize the overall residual deformation of the circuit board, ensuring its flatness; the right-hand side aims to ensure that the support forces at each support point are as uniform as possible, avoiding damage to the circuit board or the introduction of new deformation due to excessive local pressure. By adjusting the weighting coefficients α and β, the focus can be shifted to minimizing deformation or ensuring uniform support forces according to specific printing requirements, thereby achieving refined control of the fixture performance.

[0130] Specifically, step S1412-3 involves adjusting the support point positions based on stability indices. This step is the iterative core of the support point optimization process, aiming to optimize the stability index calculated in step S1412-2 by repeatedly adjusting the coordinates and / or number of support points in the two-dimensional plane. This is typically achieved by systematically exploring the support point layout space using optimization algorithms. Specifically, the adjustment process encompasses the following aspects:

[0131] First, select the optimization algorithm. Choose a suitable optimization algorithm based on the characteristics of the stability metric (e.g., whether it is differentiable, whether multiple local optima exist).

[0132] Gradient descent method: If the partial derivative of the stability index with respect to the position of the support point can be calculated or approximated, then gradient descent or its variants (such as the conjugate gradient method) can be used to iteratively adjust the position of the support point in the negative gradient direction.

[0133] Genetic Algorithm (GA): When the stability index is complex and difficult to differentiate, the genetic algorithm performs a global search in the solution space of the support point layout by simulating the mechanisms of natural selection and inheritance. It is suitable for finding the global optimal solution.

[0134] Particle Swarm Optimization (PSO): By simulating the foraging behavior of bird flocks, PSO performs a cooperative search in the solution space and is suitable for multidimensional continuous optimization problems.

[0135] Simulated annealing algorithm: It escapes local optima by accepting inferior solutions with a certain probability, and is suitable for optimization problems with complex nonlinear characteristics.

[0136] Secondly, iterative adjustments and convergence criteria are implemented. The optimization algorithm adjusts the positions of one or more support points in each iteration based on the selected strategy, then recalculates the deformation of the circuit board under the fixture support (by re-calling the finite element analysis of S132, but this time with the boundary conditions including the fixture support), and updates the stability index. Iteration continues until the change in the stability index is less than a preset threshold, or the maximum number of iterations is reached, indicating that the optimization process has converged.

[0137] Then, the number of support points is dynamically adjusted. In addition to adjusting their positions, the optimization algorithm can also dynamically increase or decrease the number of support points by introducing a decision variable of "on / off" support points. For example, if a support point does not significantly improve the stability index, or its support force is too weak, it may be removed; conversely, the density of support points can be increased in deformation hotspot areas.

[0138] Finally, constraint handling. During optimization, actual design constraints need to be considered, such as: support points cannot be located above pads (to avoid affecting printing), minimum distance between support points, and support points cannot exceed the circuit board boundaries. These constraints can be integrated into stability metrics in the form of penalty functions, or checked and corrected in each iteration using heuristic rules.

[0139] Through the above iterative adjustment process, an optimal support point layout scheme can be found, which minimizes the residual deformation of the circuit board during printing, while meeting other design and process requirements.

[0140] Specifically, step S1413 involves determining the support material and support morphology. This step aims to select a suitable physical implementation for the optimized support point layout, i.e., determining the specific material of the support point and the geometry of its contact interface with the circuit board. Material selection and morphology design directly affect the mechanical properties, wear resistance, chemical corrosion resistance, and potential damage to the circuit board of the support point, and are crucial for ensuring the long-term stability of the fixture and printing quality.

[0141] Specifically, step S1413, determining the support material and the morphology of the support component, includes:

[0142] S1413-1, conduct mechanical property evaluation and selection of support materials;

[0143] S1413-2, Design the morphology of the interface between the support component and the circuit board;

[0144] S1413-3, Optimize the interaction mechanics of the contact interface between the support and the circuit board.

[0145] Specifically, step S1413-1 involves evaluating and selecting the mechanical properties of the support material. It should be understood that the purpose of this step is to select the most suitable support material based on the load the fixture support point needs to withstand, the working environment conditions, and the sensitivity of the circuit board. The choice of material directly affects the stiffness, elasticity, hardness, wear resistance, temperature resistance, and surface friendliness of the support point. Specifically, the material evaluation and selection considers the following aspects:

[0146] First, mechanical performance requirements.

[0147] Hardness: The support material needs to be hard enough to withstand the printing pressure, but not too hard to avoid scratching the surface of the ultra-thin circuit board. Materials with a hardness slightly lower than the surface material of the circuit board (such as solder mask or copper pads) are typically chosen. For example, engineering plastics with a Shore D hardness between 60 and 80, or rubbers with specific hardness levels, can be used.

[0148] Modulus of elasticity: The support point needs to have a certain degree of elasticity to accommodate minor unevenness of the circuit board and provide uniform support force. Too high a modulus of elasticity may lead to stress concentration, while too low a modulus of elasticity will result in poor support.

[0149] Compressive strength and fatigue resistance: The support material needs to be able to withstand repeated printing pressure over a long period of time without plastic deformation or fatigue failure.

[0150] Secondly, thermal performance requirements.

[0151] Coefficient of thermal expansion: The coefficient of thermal expansion of the support material should be as close as possible to that of the circuit board material, or have a small difference, in order to reduce additional stress or deformation caused by thermal expansion mismatch when the printing environment temperature changes.

[0152] Temperature resistance: The support material must be able to withstand the corresponding operating temperature during printing and possible cleaning processes (e.g., room temperature printing or high temperature printing).

[0153] Finally, the compatibility of chemistry and physics.

[0154] Chemical resistance: The support material should be able to resist corrosion from chemicals such as solder paste, flux, and cleaning agents to ensure long-term performance.

[0155] Coefficient of friction: The coefficient of friction between the support material and the circuit board should be moderate, so as to effectively fix the circuit board and prevent it from sliding, without generating excessive shearing force during the picking and placing process.

[0156] Conductivity / Insulation: Select conductive or insulating materials based on the electrical requirements of the circuit board.

[0157] Commonly used support materials include engineering plastics (such as polyetheretherketone, polyoxymethylene), rubber or silicone, polyurethane with specific hardness, and composite materials. The selection process may involve mechanical testing, thermal testing, and environmental adaptability testing of different materials, combined with cost-benefit analysis.

[0158] Specifically, step S1413-2 involves designing the morphology of the contact interface between the support and the circuit board. It should be understood that the purpose of this step is to optimize the geometry of the direct contact area between the support and the ultra-thin circuit board to achieve the best support effect, including uniformly distributing contact pressure, minimizing stress concentration, preventing circuit board damage, and improving adaptability to minor deformations of the circuit board. The morphology design of the contact interface is particularly critical for ultra-thin circuit boards because they are extremely sensitive to localized pressure. Specifically, the morphology design considers the following aspects:

[0159] First, consider the contact area and pressure distribution. Design an appropriate contact area based on the required support force. Too small a contact area can lead to excessively high localized pressure, potentially damaging the circuit board or causing localized indentations; too large a contact area may affect the printed area or result in excessive spacing between support points. The goal is to achieve a uniform distribution of contact pressure, avoiding stress concentration at the contact edges.

[0160] Secondly, geometric shape.

[0161] Planar contact: For relatively flat areas, planar contact can be used, but the edges need to be chamfered or rounded to avoid sharp edges scratching the circuit board.

[0162] Curved or spherical contact surfaces: For areas that need to accommodate minor curvature deformations of the circuit board, or for better stress distribution, curved or spherical contact surfaces can be used. For example, a spherical surface with a large radius can ensure a certain degree of accommodation for minor warping of the circuit board while providing a larger effective support area.

[0163] Conical or cylindrical surfaces: These may be used for certain positioning requirements, but their contact with the circuit board must be strictly controlled to avoid excessive local stress.

[0164] Spring or flexible material integration: To provide more adaptive support, springs or materials with a specific flexible modulus can be integrated into the support, enabling it to provide cushioning and adaptive support force according to the actual deformation of the circuit board.

[0165] Next, surface roughness and treatment. The surfaces of the support contact surfaces should have low roughness, typically polished or finely machined to reduce wear on the circuit board surfaces (e.g., solder mask or copper surfaces). Specific coating treatments may also be applied to the surface, for example, to increase wear resistance or reduce the coefficient of friction.

[0166] Finally, arraying or microstructuring: For large-area support requirements, an array of multiple tiny support units can be designed, such as a micro-column or mesh structure, to achieve more precise support control and pressure distribution.

[0167] By meticulously designing the contact interface morphology between the support component and the circuit board, effective support can be ensured while maximizing the protection of the ultra-thin circuit board from damage and optimizing printing quality.

[0168] Specifically, step S1413-3 optimizes the interaction mechanics of the contact interface between the support and the circuit board. This step aims to finely adjust the local mechanical behavior of the contact area between the support and the circuit board through detailed mechanical analysis and numerical simulation, thereby ensuring optimal support performance and avoiding any form of damage to the ultra-thin circuit board. This includes quantitative analysis of contact pressure, shear force, friction, and local deformation. Specifically, optimizing the interaction mechanics involves the following aspects:

[0169] First, a contact mechanics model is established. Based on the shape of the support component designed for S1413-2, a contact mechanics model is established between it and the ultra-thin circuit board. This can be achieved using Hertz contact theory or the more general finite element contact analysis method. The model needs to consider the elastic modulus, Poisson's ratio, and friction coefficient of the support material, as well as the local mechanical properties of the circuit board.

[0170] Secondly, the contact pressure distribution is evaluated. After applying the support force optimized in S1412-2, the pressure distribution on the contact interface is simulated and calculated. The goal is to ensure that the contact pressure is uniform throughout the contact area and that the maximum contact pressure value is lower than the allowable compressive stress of the circuit board material to prevent the circuit board from being indented or damaged. If uneven pressure distribution or stress concentration is found, the topography design in S1413-2 needs to be retrospectively adjusted.

[0171] Next, shear force and friction analysis is performed. The in-plane shear forces that may occur during the printing process are assessed. As the squeegee moves across the stencil, it exerts shear forces on the circuit board through the stencil and solder paste (or ink). The fixture's fixation scheme needs to resist these shear forces to prevent minor in-plane movement of the circuit board during printing. Simultaneously, the friction between the support points and the circuit board is analyzed to ensure that, without affecting positioning, the friction is not excessive and could cause wear to the circuit board.

[0172] Finally, local deformation and stress concentration analysis were performed. In a high-precision finite element model, the circuit board near the support point was locally meshed to simulate the microscopic deformation and stress distribution when the support contacted the circuit board. Particular attention was paid to whether stress concentration occurred at the contact edges or abrupt shape changes. If the stress concentration exceeded the material's elastic limit or fatigue limit, the support morphology needed to be redesigned or the support force adjusted.

[0173] By finely optimizing these interaction mechanics, it can be ensured that the fixture support macroscopically suppresses the overall deformation of the circuit board, while microscopically causing no damage to the ultra-thin circuit board, thereby achieving high planar stability and printing quality of the circuit board during the printing process.

[0174] Specifically, step S142 involves designing the overall structure and auxiliary functional modules of the fixture. It should be understood that, after determining the core support point distribution and mechanical parameters, this step aims to integrate these support functions into a complete, practical, and efficient fixture structure, and equip it with necessary auxiliary functions to meet the requirements of ease of operation, precision, durability, and cost-effectiveness in actual production environments. This step transforms the abstract design scheme into a manufacturable physical product. Specifically, the design of the overall fixture structure and auxiliary functional modules covers the following aspects:

[0175] First, the main frame design. The main frame of the fixture should have sufficient rigidity and stability to resist the pressure applied by the squeegee during printing and prevent deformation. The frame material is typically a high-strength metal with a low coefficient of thermal expansion (e.g., aluminum alloy, stainless steel) or a high-density engineering plastic. The frame structure design should consider the force flow path to ensure that the supporting force can be effectively transferred from the bottom of the fixture to the support points.

[0176] Secondly, support component integration. The support points and their morphological designs determined in S141 are integrated into the main frame. This can be achieved in several ways, for example:

[0177] Fixed support: The support components are directly fixed to the main body of the fixture through machining or bonding.

[0178] Adjustable support: To accommodate different circuit board models or to allow for fine-tuning, the support can be designed as a detachable, replaceable, or height-adjustable structure (e.g., via threads or fine-tuning mechanisms).

[0179] Suction cup or vacuum adsorption: For extremely thin or large-area circuit boards, vacuum suction cup technology can provide uniform bottom support while reducing the number of contact points on the circuit board.

[0180] Then, the circuit board fixing and positioning mechanism.

[0181] Edge clamping or pressing: Adjustable clamps or pressure bars are designed to fix the circuit board by applying uniform pressure to the edge of the circuit board, preventing in-plane movement during the printing process.

[0182] Locating pins: Using locating holes on the circuit board, high-precision locating pins are used to precisely align the circuit board into the reference coordinate system of the fixture. The material and tolerances of the locating pins must be strictly controlled to ensure repeatability and accuracy.

[0183] Quick loading and unloading mechanism: The design features an easy-to-operate locking or releasing mechanism, allowing operators to quickly and accurately load and unload circuit boards, thereby improving production efficiency.

[0184] Finally, the design of auxiliary function modules.

[0185] Cleaning and maintenance access: The fixture design should take into account the ease of cleaning solder paste or ink residue, for example, by designing an easily disassembled modular structure or leaving cleaning access.

[0186] Visualization or inspection window: Without affecting the support, reserve a portion of the area to allow the operator to observe the printing process or perform optical inspection.

[0187] Anti-static design: Since ultra-thin circuit boards are sensitive to static electricity, the materials and structure of the fixture should take into account anti-static measures, such as using conductive materials, grounding design or anti-static coating.

[0188] Modular and standardized: The modular design of the components facilitates quick configuration and interchange according to different circuit board sizes or process requirements, reducing the customization cost and replacement time of the fixtures.

[0189] Through these comprehensive design considerations, a fully functional, high-performance, and easy-to-operate ultra-thin circuit board printing fixture can be constructed.

[0190] In the above-described printing fixture design method based on ultra-thin circuit board printing technology, step S150 involves fixture design verification and optimization. This step is understood to be a closed-loop link in the fixture design process. Its purpose is to systematically evaluate whether the fixture designed in step S140 can effectively suppress the deformation of the ultra-thin circuit board and meet all preset printing quality requirements. Through rigorous verification, potential problems in the design can be identified and necessary adjustments and optimizations can be made, thereby ensuring that the fixture finally put into production has high reliability and excellent performance.

[0191] Specifically, the design verification and optimization of fixtures mainly includes the following sub-steps:

[0192] First, a re-verification based on finite element analysis is performed. The fixture support structure and fixing scheme designed in step S140 are integrated into the ultra-thin circuit board mechanical model constructed in step S120 as new boundary conditions. Then, the deformation mechanics simulation analysis in step S130 is executed again. The simulation results are compared with the initial deformation data without fixture support, focusing on evaluating the improvement effect of the fixture on the maximum deflection of the circuit board, the relative displacement of key pad areas, and the overall flatness. If the simulation results show that the residual deformation still exceeds the preset tolerance, it is necessary to backtrack to step S141 or S142, readjust the support point layout, support material, or fixture structure, and conduct a new round of optimization iterations.

[0193] Secondly, physical prototype manufacturing and testing. Based on the final fixture design, one or more physical prototypes of the fixture are manufactured. Then, a series of trial printing tests are conducted on the actual printing production line using ultra-thin circuit boards.

[0194] Deformation Measurement: During the trial printing process, high-precision optical measurement equipment (such as 3D scanners, laser displacement sensors, or digital image correlation technology) is used to measure the actual deformation of the ultra-thin circuit board in real time or at key stages. The measured deformation data is compared with the simulation prediction data to verify the accuracy of the mechanical model.

[0195] Printing quality assessment: Rigorous quality inspection is performed on the printed circuit boards. This includes the uniformity of solder paste or ink thickness, printing position accuracy (deviation from the design position), bridging, missing prints, cold solder joints, and other defect types and their occurrence rates. Automated inspection is performed using optical inspection (AOI) equipment, X-ray inspection equipment, etc.

[0196] Production efficiency and ease of operation assessment: Evaluate the loading and unloading speed, operational difficulty, ease of cleaning, and compatibility with existing equipment of the fixture on the actual production line, and collect operator feedback.

[0197] Next, performance indicators are quantified and compared. Test data is statistically analyzed to quantify various performance indicators of the fixture, such as the percentage improvement in printing yield, maximum residual deformation, and printing accuracy indicators (e.g., root mean square value of pad center offset). These quantified indicators are compared with design goals and existing technology levels to evaluate the superiority of the fixture design of this invention. Finally, optimization and feedback loops are implemented. If the verification results do not fully meet the expected goals, or new problems are discovered (e.g., wear after prolonged use, compatibility issues with specific batches of circuit boards), an optimization feedback loop needs to be initiated. Based on the specific problems in the verification results, their root causes are analyzed, and the fixture design is modified accordingly. For example, if significant deformation is still found in a specific area, it may be necessary to increase the number of support points in that area; if the support wears too quickly, it may be necessary to replace it with a more wear-resistant material or improve its morphology. Through continuous verification, analysis, and optimization, a high-performance ultra-thin circuit board printing fixture design that meets production requirements is finally obtained.

[0198] In summary, the printing fixture design method based on ultra-thin circuit board printing technology, as described in this application, is elucidated. It systematically acquires circuit board design parameters and printing process requirements, constructs an accurate deformation mechanics model of the ultra-thin circuit board, and conducts detailed deformation mechanics simulation analysis to predict printing deformation. Subsequently, based on the simulation analysis results, the distribution of support points, support mechanical parameters, support materials, and morphology of the fixture are intelligently optimized, and a complete fixture structure and auxiliary functional modules are designed. Finally, the fixture design is comprehensively evaluated and optimized through rigorous simulation and physical verification. This method transforms empirical design into data-driven scientific design, achieving precise design and performance optimization of ultra-thin circuit board printing fixtures. It effectively solves the industry problem of easy deformation of ultra-thin circuit boards during printing, leading to a decrease in yield, and significantly improves printing accuracy and production efficiency.

Claims

1. A method for designing a printing fixture based on ultra-thin circuit board printing technology, characterized in that, include: Obtain the geometric and material mechanical parameters of the ultrathin circuit board to be designed for the printing fixture; A deformation mechanical model of ultrathin circuit boards under combined loads during the printing process is established. The mechanical model considers the nonlinear behavior of materials, large deformation characteristics and thermo-mechanical coupling effects. Based on the aforementioned deformation mechanics model, simulation analysis is performed to predict the deformation behavior of ultra-thin circuit boards under combined loads. This deformation behavior includes displacement distribution, stress distribution, local warpage, and printing alignment error. The process includes: static analysis of the mechanical model using finite element analysis software to predict the displacement, stress, and strain distributions of the ultra-thin circuit board under stable printing pressure; transient dynamic analysis of the mechanical model using finite element analysis software to simulate the deformation response during the dynamic process of squeegee movement and temperature changes; buckling analysis of the mechanical model using finite element analysis software to assess the possibility of structural instability of the ultra-thin circuit board under printing pressure; multi-condition prediction of the deformation behavior of the ultra-thin circuit board under different combinations of printing parameters, including different squeegee pressures, squeegee speeds, and printing temperatures; and outputting simulation analysis results, including the maximum displacement of key areas, local warpage, stress concentration areas, and predicted printing alignment error. Based on the simulation analysis results, the structural layout, support scheme, clamping mechanism, and positioning mechanism of the fixture are designed, and appropriate fixture materials are selected. This includes: optimizing the distribution of support points or support surfaces of the printing fixture based on the deformation characteristics determined by the simulation analysis results to evenly distribute the load borne by the ultra-thin circuit board and avoid stress concentration; designing the clamping mechanism of the printing fixture, which adopts flexible clamping or vacuum adsorption; designing the positioning mechanism of the printing fixture, which includes high-precision positioning pins and edge clamping components; selecting the body material of the printing fixture, which has high rigidity, low coefficient of thermal expansion, and excellent wear resistance, and the body material covers high-strength aluminum alloy or engineering ceramics; and selecting the contact surface material between the printing fixture and the ultra-thin circuit board, which has flexibility, low coefficient of friction, and anti-static properties, and the contact surface material covers silicone rubber or polyurethane elastomer. The design of the printing fixture is optimized to minimize the printing deformation and printing alignment error of the ultra-thin circuit board and maximize the printing yield.

2. The printing fixture design method based on ultra-thin circuit board printing technology according to claim 1, characterized in that, The specific steps of obtaining the geometric and material mechanical parameters of the ultrathin circuit board to be designed for the printing fixture include: Obtain the thickness, length, width, and number of layers of the ultrathin circuit board; The elastic modulus, Poisson's ratio, coefficient of thermal expansion, and yield strength of the substrate material and conductor material used in the ultra-thin circuit board are obtained. The geometric parameters and material mechanical parameters of the ultrathin circuit board are obtained by consulting the circuit board design drawings, the data manual provided by the material supplier, and conducting physical performance tests, and a data verification mechanism is introduced.

3. The printing fixture design method based on ultra-thin circuit board printing technology according to claim 1, characterized in that, The establishment of the deformation mechanical model of the ultrathin circuit board under the combined load during the printing process specifically includes: The ultrathin circuit board is discretized into finite element mesh elements, and corresponding material properties are defined for each mesh element. Define the composite load that the ultra-thin circuit board bears during the printing process, the composite load including printing squeegee pressure, screen tension, ambient temperature change, vacuum suction force and fixture clamping force; In the aforementioned mechanical model, a multi-scale mechanical model is further established to simulate the influence of microstructure on macroscopic deformation behavior.

4. The printing fixture design method based on ultra-thin circuit board printing technology according to claim 3, characterized in that, Establishing the deformation mechanical model of the ultrathin circuit board under combined loads during the printing process further includes: Choose at least one of the shear deformation plate model based on Mindlin-Reissner theory or Kirchhoff thin plate theory as the mechanical theory model to describe the mechanical behavior of the ultrathin circuit board. Establish equivalent mechanical parameters or a layered material model of the composite material of the ultrathin circuit board composed of dielectric substrate and copper foil; Apply boundary conditions and load conditions, which include the self-weight load of the circuit board, thermal load, and the initial support conditions of the printing table.

5. The printing fixture design method based on ultra-thin circuit board printing technology according to claim 1, characterized in that, The simulation analysis based on the aforementioned deformation mechanics model further includes: The geometric model of the ultrathin circuit board is imported into the simulation analysis software, high-quality mesh generation is performed, and the elastic modulus, Poisson's ratio, shear modulus, density and thermal expansion coefficient of each layer of the ultrathin circuit board are accurately applied. Precisely set load parameters, including mapping the scraper pressure value to the circuit board surface area corresponding to the stencil opening, defining temperature load, and applying the circuit board's own gravity. Define boundary conditions, which include initial support conditions or symmetrical boundary conditions for the circuit board to be placed on the printing table. The simulation results are post-processed, including displacement field visualization, stress and strain distribution, and extraction of maximum deflection value, relative displacement of each pad region, and deformation gradient.

6. The printing fixture design method based on ultra-thin circuit board printing technology according to claim 1, characterized in that, Optimize the distribution of support points or support surfaces of the printing fixture, and design the clamping mechanism and positioning mechanism, specifically including: Based on the deformation hotspot identification in the simulation analysis results, the initial support point is determined. The deformation hotspot identification includes the identification of the maximum deflection point, the identification of high stress concentration areas, the deformation assessment of key pad areas, and the consideration of edge and corner deformation. The layout and number of support points are optimized. The optimization includes constructing a support point distribution influence matrix to quantify the influence of a single support point on the overall deformation behavior of the circuit board, calculating the stability index of the support point distribution to comprehensively evaluate the overall flatness and residual deformation level of the circuit board, and adjusting the position of the support points based on the stability index.

7. The printing fixture design method based on ultra-thin circuit board printing technology according to claim 1, characterized in that, The selection of the body material of the printing fixture and the material of the contact surface with the ultra-thin circuit board specifically includes: The mechanical properties of the supporting materials are evaluated and selected, and the evaluation considers hardness, elastic modulus, compressive strength, fatigue resistance, coefficient of thermal expansion, temperature resistance, chemical corrosion resistance, coefficient of friction, and electrical or insulating properties. The design of the morphology of the contact interface between the support component and the circuit board takes into account the contact area and pressure distribution, geometry, surface roughness, and arraying or microstructuring. Optimize the interaction mechanics between the support component and the circuit board contact interface. Optimization includes establishing a contact mechanics model, evaluating the contact pressure distribution, analyzing shear force and friction, as well as local deformation and stress concentration.

8. The printing fixture design method based on ultra-thin circuit board printing technology according to claim 1, characterized in that, Optimizing the design of the printing fixture to meet the requirements of printing accuracy and yield specifically includes: Set optimization objectives, which include minimizing printing deformation of ultra-thin circuit boards, minimizing printing alignment error, and maximizing printing yield. The structure of the printing fixture is optimized by applying a topology optimization algorithm to reduce weight and optimize material distribution while maintaining the necessary stiffness. The geometric dimensions, support parameters, and material selection of the printing fixture are iteratively adjusted using a parameter optimization algorithm, and the optimal combination of design parameters is found through repeated simulation analysis. The mechanical modeling, deformation simulation, fixture structure design and optimization algorithm of the ultra-thin circuit board are integrated into the automated design platform to achieve parameterization and rapid design iteration; We conducted actual printing verification by prototyping sample fixtures, and provided feedback and further optimization of the fixture design based on the actual printing results.

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