Electrofluidic printing equipment and method for high-precision complex hard surface conformal circuits

Abstract

The present invention discloses an electrofluidic printing device and method for high-precision, complex, hard-curved, conformal circuits, comprising a support frame, a Y-axis group provided in the support frame, a support structure provided on the Y-axis group for translational motion along the Y-axis, a B rotation module supported on the support structure for rotational motion around the Y-axis, a C rotation module provided on the B rotation module for rotational motion around the Z-axis, a workbench provided on the C rotation module, an X-axis group provided on the top of the support frame, one end of the X-axis group connected to a Z-axis group for translational motion along the X-axis, a conformal printing module and a vision module provided on the bottom end of the Z-axis group corresponding to the workbench for translational motion along the Z-axis, the conformal printing module and the vision module being electrically connected to a host computer. The electrofluidic printing device and method for high-precision, complex, hard-curved, conformal circuits of the present invention solve the technical problems of difficult processing of high-precision, complex curved circuits and poor printing accuracy and effect.

Description

Technical Field

[0001] The present invention belongs to the field of electrohydrodynamic printing technology, and specifically relates to an electrohydrodynamic printing device for high-precision, complex, hard-curved, conformal circuits. The present invention also relates to an electrohydrodynamic printing method for high-precision, complex, hard-curved, conformal circuits. Background Art

[0002] Conformal electronics is one of the most disruptive and promising emerging information technologies today. It involves new materials and micro-nano manufacturing techniques, and has widespread applications in aerospace, intelligent sensing, and new energy. Three-dimensional curved electronic products are a trend in the microelectronics industry. The ability to directly mold circuits onto the surface of a product structure not only achieves structural and functional integration, but also makes electronic products more miniaturized, intelligent, and lightweight. Conformal electronics possess the unique ability to conform to complex curved surfaces while retaining the electronic functionality of planar integrated circuit technology. This enables electronic devices to be applied more widely in complex and diverse scenarios. This is crucial for integrating functions such as health monitoring, environmental sensing, and frequency-selective surfaces, such as intelligent sensing skins for aircraft, stealthy electromagnetic functional structures, and curved conformal antennas. Currently, the manufacturing technology for curved electronics can be broadly divided into two modes: direct manufacturing, where functional conductive materials, devices, or components are directly fabricated onto a curved surface; and indirect manufacturing, where planar electronic devices are indirectly transferred onto a curved substrate via a flexible substrate or subjected to external stimuli such as heat, light, or magnetism to cause the device to bend and deform. Transfer printing has been widely used due to its advantages in large-area feature size and low cost, but it still has disadvantages such as cumbersome process, large material waste rate and poor controllability. Especially for non-stretchable systems, indirect transfer technology is difficult to achieve complete conformal coverage on complex hard surfaces through geometric transformation, and the self-assembly process cannot transform non-expandable structures (such as spherical or irregular shapes) into the target curved surface shape. Importantly, existing curved electronic products are mainly flexible manufactured in 2.5 dimensions, and cannot solve the basic problems related to complex curved surfaces, that is, planar flexible electronics cannot be fully fitted with complex surfaces (especially non-expandable surfaces with changing curvature) through geometric transformation (transfer, pad printing and assembly), making it difficult for the mechanical and electrical properties of curved electronics to meet the use requirements. In addition, when the degree of bending or the number of bending times of the planar circuit fitted on the curved surface reaches a certain value, the ultra-thin electronic structure will be very prone to defects such as interface delamination and fracture, difficulty in signal collection, and unstable signal collection under strong bending or stretching conditions. Therefore, achieving stable conformal circuits on complex hard surfaces while avoiding wrinkles and buckling is key to curved electronics manufacturing. Regardless of the chosen approach, fabricating large quantities of high-quality curved electronic conductive circuits is undoubtedly a crucial step in curved conformal electronics manufacturing.

[0003] There is no mature preparation process for the direct printing of curved circuits. The direct printing technologies that can be realized at present mainly include 3D printing, laser direct writing, aerosol jet, inkjet printing and micro-pen direct writing. Some universities and research institutes at home and abroad (such as MIT, Suzhou Institute of Nano-Tech and Nano-Bionics of the Chinese Academy of Sciences, etc.) are using traditional 3D printing methods to conduct hard curved circuit research. There are two main modes: one is to use additive manufacturing to produce three-dimensional spatial structures, which can include curved surfaces, but can only prepare simple three-dimensional or curved structures within the spatial range, and cannot complete the conformal and patterned manufacturing of curved functional electronic devices, and cannot prepare complex, high-quality circuits that meet application requirements; the second is to use 3D direct writing technology to directly print conductive materials on the surface of the substrate. This process is only suitable for flat curved surface areas with small curvature, but cannot meet the requirements of conformal printing of complex curved surfaces because of the large amount of material required during printing. During the printing process, traditional three-axis motion systems are unable to rotate the printed surface on a curved surface to a horizontal state, and cannot keep the nozzle parallel to the normal direction of the printed surface and perpendicular to the surface to be processed in real time. This causes the extruded material to deviate from the printing trajectory and deform, flow out, and explode when it lands on a curved surface with changing curvature. Laser direct writing often completes the manufacture of curved circuits by modifying the curved substrate material. This process has requirements for the base material, a narrow range of applications, and is not environmentally friendly. The Chinese Academy of Sciences uses a functional pen with heating capabilities to write various patterns and circuits directly on curved surfaces. However, this process has low resolution and must complete circuit manufacturing in a short time, making it difficult to meet the needs of printing on any curved surface. The inkjet printing process is more flexible and does not require templates or masks. Functional inks can be printed directly on the surface of the substrate without any physical contact between the substrate and the nozzle, making it suitable for the efficient manufacture of large-area curved electronics. Traditional inkjet printing technology mainly uses electrostatic continuous, piezoelectric and thermal bubble inkjet, which has the following problems: low printing resolution (≥20 μm), droplet size is limited by the nozzle diameter (ink droplet diameter ≈ nozzle diameter × 2), nozzles are easily clogged and the nozzle manufacturing process is complex; Optomec in the United States has applied aerosol printing technology to the conformal printing process of curved circuits. Although aerosol jet can directly produce a directional and collimated aerosol beam, this process can only perform continuous printing. The solvent evaporates quickly during the atomization process and produces a large number of satellite droplets, which will seriously affect the film-forming effect and adhesion of the ink. In addition, this process cannot solve the shortcomings encountered by traditional inkjet printing, such as precise positioning, excessively wide printing line width, and the harsh experimental conditions caused by the need for air circuits.

[0004] Electrofluidic printing is a new type of printing method. Unlike traditional inkjet printing, which uses a "squeeze" method, electrofluidic printing uses an electric field to drive a "pull" method to produce an extremely fine jet from the tip of a formed "Taylor cone." This method offers advantages such as easy ejection of particles or polymer solutions without clogging and the ability to print high-viscosity (≤10,000 mPa.s) conductive liquids. Its printing resolution is not directly affected by nozzle diameter, and submicron resolution (>0.3 μm) can be achieved. It can be used in areas such as curved electronic circuits, solar cells, and biofunctional devices. Therefore, the use of electrofluidic printing to replace traditional inkjet printing technology for curved electronic fabrication is gaining widespread acceptance and application. Although the application of electrofluidic printing on curved surfaces has been studied and demonstrated good print quality, existing electrofluidic conformal printing methods are not suitable for substrates with large curvatures. The electric field on the curved surface can interfere with the electrofluidic jet flow, thus affecting print quality. Specifically, when the nozzle prints on a surface with different curvatures, the direction of the jet is not vertically downward, but is "pulled" by the lateral electric field. This creates two problems for printing: (1) Since the jet is "pulled" by the lateral electric field, the landing point of the jet is inconsistent with the actual motion trajectory of the nozzle, affecting the positioning accuracy of the printing; (2) The normal distance between the nozzle and the substrate will decrease, while the voltage between the nozzle and the substrate is fixed, which means that the inter-electrode field strength will increase, causing the electrohydrodynamic printing jet to become turbulent. For this reason, the current more mature electrohydrodynamic printing equipment, in order to ensure the stability of the electric field, limits the printing direction to be perpendicular to the substrate and the conditions that the height of the nozzle and the substrate remains unchanged. It can only use a three-axis motion system to complete the printing operation on a flat substrate, specifically including printing on a hard flat substrate such as silicon, glass, and a flexible flat medium. In addition, when the shape of the curved substrate changes in complexity, the curvature of the curved substrate, the local normal direction and the real-time change of the substrate from the nozzle height during the printing process will also affect the uniformity of the applied electric field, and a stable electric field cannot be formed by relying on the existing printing method, which can not meet the uniformity and stability requirements of the curved circuit follow-up printing. Furthermore, when using a conductive material as a substrate to carry out electrofluid inkjet printing, the electric charge of the printed droplets can be eliminated by substrate conduction, but when printing on an insulating material substrate, due to the low electrical conductivity of the insulating material, the electric charge of the deposited droplets cannot be eliminated by the substrate, causing the substrate charge accumulation, and easily causing the insulating substrate to undergo polarization under a strong electric field. If the polarized charge generated cannot be eliminated by conduction, the problem of charge accumulation will be more serious, and the accumulated charge will produce further interference to the spatial electric field, thereby affecting the form and jet trajectory of the subsequent deposited droplets. Therefore, the above problems have severely limited the application of electrofluidic printing technology in the follow-up printing of high-precision curved circuits, and the electrofluidic power printing equipment that can now complete the follow-up printing of curved circuits is very rare.The only devices or methods that can conformally print curved circuits can only be used for simple surfaces, such as spheres or ellipsoids with relatively small curvatures. However, for complex surfaces such as arbitrary surfaces, surfaces with large variations in curvature radius, or parametric surfaces containing sine and cosine functions, conformal printing cannot be completed. In summary, although there are related technologies that can complete the printing of some curved circuits, it is still a world-class problem to truly achieve direct printing of circuits on arbitrary surfaces with complex shapes (especially concave surfaces with large curvature). Therefore, in view of the urgent need for conformal printing of curved functional electronic devices, it is of great significance to design a high-precision complex hard curved surface electro-hydrodynamic conformal printing system to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide an electrofluid printing device for high-precision complex hard-curved conformal circuits, which solves the problems of difficult processing and poor printing accuracy of existing high-precision complex curved circuits.

[0006] Another object of the present invention is to provide an electrofluid printing method for high-precision, complex, hard-curved conformal circuits.

[0007] The first technical solution adopted by the present invention is: an electrofluid printing device for high-precision, complex, hard-curved conformal circuits, including a support frame, a Y motion axis group is provided in the support frame, a support structure for translational motion along the Y axis is provided on the Y motion axis group, a B rotation module for rotational motion around the Y axis is supported on the support structure, a C rotation module for rotational motion around the Z axis is provided on the B rotation module, a workbench is provided on the C rotation module, an X motion axis group is provided on the top of the support frame, one end of the X motion axis group is connected to a Z motion axis group for translational motion along the X axis, a conformal printing module and a vision module for translational motion along the Z axis are provided at the bottom end of the Z motion axis group corresponding to the workbench, and the conformal printing module and the vision module are electrically connected to a host computer.

[0008] The first technical solution of the present invention is also characterized in that:

[0009] The form-fitting printing module includes an ink cartridge, which is connected to a flow pump electrically connected to the upper computer through a pipe. A nozzle with the bottom facing downward is fixedly connected to the bottom of the ink cartridge through a conduit. Electrode rings are coaxially arranged at intervals below the nozzle. The electrode rings and the outer wall of the nozzle are electrically connected in turn to a function generator electrically connected to the upper computer and a grounded AC power supply.

[0010] The vision module includes a positioning camera and an observation camera located on both sides of the ink cartridge and electrically connected to the upper computer. The positioning camera is perpendicular to the curved surface substrate to be printed, and the observation camera is aligned with the nozzle.

[0011] A Y-axis drive motor electrically connected to the upper machine is arranged along the Y-axis at one end of the Y motion axis group. A grating scale electrically connected to the upper machine is arranged on the Y-axis drive motor. The output end of the Y-axis drive motor is coaxially connected to a lead screw passing through the support structure and threadedly engaged with the support structure through a coupling.

[0012] One end of the B rotation module is fixedly connected to a B-axis drive motor electrically connected to the host computer along the Y axis. The B-axis drive motor is provided with a grating scale, a gravity sensor and a posture sensor, all of which are electrically connected to the host computer.

[0013] A C-axis drive motor located on the B rotation module and electrically connected to the host computer is fixedly connected along the Z axis below the C rotation module. The C-axis drive motor is provided with a grating scale, a gravity sensor and a posture sensor, all of which are electrically connected to the host computer.

[0014] An X-axis drive motor electrically connected to the host computer is arranged along the X-axis on one side of the X-axis motion axis group. A grating scale electrically connected to the host computer is arranged on the X-axis drive motor. The output end of the X-axis drive motor is coaxially connected to a lead screw passing through the Z-axis motion axis group and threadedly engaged with the lead screw through the Z-axis motion axis group through a coupling.

[0015] A Z-axis drive motor electrically connected to the upper computer is arranged along the Z-axis at the top of the Z motion axis group. A grating scale electrically connected to the upper computer is arranged on the Z-axis drive motor. The output end of the Z-axis drive motor is coaxially connected to a lead screw through a coupling that passes through the base plate that fixes the conformal printing module and the vision module and is threadedly engaged with them.

[0016] The second technical solution adopted by the present invention is: an electrofluid printing method for high-precision complex hard surface conformal circuits, comprising the following steps:

[0017] Step 1: Create a 3D model of the curved surface substrate to be printed, import the required printed circuit and corresponding process state requirements into the 3D model, and plan the layout and placement of the curved surface space based on the selection of electronic components. Then, place the curved surface substrate to be printed on the workbench.

[0018] Step 2: Directly conformally map the planar circuit onto the surface to be printed on the 3D model, and perform CAM path process planning on the mapped surface circuit. Specifically, the mapped surface circuit is decomposed into multiple line segments, and a printing trajectory sequence is set for each line segment. Each line segment is discretized into multiple discrete points. Based on the position of the surface substrate to be printed on the workbench, the five-degree-of-freedom motion trajectory position and process state requirements of each discrete point are obtained.

[0019] Step 3: The motion trajectory position and process state requirements of the discrete points are parsed into instructions for the host computer. The host computer prints in sequence according to the printing trajectory, thereby completing the conformal printing of the required printed circuit on the surface of the curved substrate to be printed.

[0020] The second technical solution of the present invention is also characterized in that:

[0021] The motion trajectory position in step 2 includes the X-axis, Y-axis, and Z-axis as well as the rotation coordinates rotating around the Y-axis and Z-axis; the process state requirements include the voltage applied by the function generator and the flow rate of the nozzle controlled by the flow pump.

[0022] The beneficial effects of the present invention are as follows: the electrofluidic printing equipment and method for high-precision, complex, hard-curved conformal circuits employ a five-degree-of-freedom motion platform combining a three-axis translational platform with a two-axis rotational platform. Simultaneously, the electric field between the ink, electrode ring, and the curved substrate to be printed forms a potential gradient, thereby ensuring the stability of the electric field for curved surface printing. This solves the technical problems of difficult processing of high-precision, complex curved circuits and poor printing accuracy and performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a front view of the electrofluidic printing device for high-precision, complex, hard-curved conformal circuits of the present invention;

[0024] Figure 2 This is a left view of the electrofluidic printing device for high-precision, complex, hard-curved conformal circuits of the present invention;

[0025] Figure 3 It is a schematic diagram of the five-degree-of-freedom motion relationship of the electro-fluid printing device of the present invention for high-precision complex hard-curved surface conformal circuits;

[0026] Figure 4 It is a structural schematic diagram of the conformal printing module in the electrofluidic printing device for high-precision, complex, hard-curved conformal circuits of the present invention;

[0027] Figure 5 This is a schematic diagram of an automobile curved surface circuit to be printed, constructed by the electrofluidic printing method of the present invention for high-precision, complex, hard-curved surface conformal circuits;

[0028] Figure 6 The present invention is a schematic diagram of a circuit for a complex human face surface to be printed, which is constructed by the electro-fluid printing method for high-precision complex hard-surface conformal circuits.

[0029] In the figure, 1. Z motion axis group, 2. X motion axis group, 3. conformal printing module, 4. coupling, 5. X-axis drive motor, 6. vision module, 7. nozzle, 8. observation camera, 9. C-axis drive motor, 10. support frame, 11. curved substrate to be printed, 12. electrode ring, 13. positioning camera, 14. screw, 15. Z-axis drive motor, 16. ink cartridge, 17. workbench, 18. C rotation module, 19. rotation module, 20. B rotation module, 21. Y motion axis group, 22. Y-axis drive motor, 23. B-axis drive motor, 24. motion module, 25. linear movement along the Z-axis direction, 26. linear movement along the X-axis direction, 27. C-axis rotational movement, 28. B-axis rotational movement, 29. linear movement along the Y-axis direction, 30. host computer, 31. function generator, 32. AC power supply, 33. Taylor cone. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Example 1

[0032] The present invention provides an electrofluid printing device for high-precision complex hard surface conformal circuits, such as Figures 1 to 4 As shown, it includes a five-axis linkage mechanical structure, a form-fitting printing module 3, a visual module 6, and a host computer control system.

[0033] 1) Five-axis linkage mechanical structure

[0034] Figure 1 and Figure 2In the figure, the X-axis drive motor 5, Y-axis drive motor 22, Z-axis drive motor 5, and Z-axis drive motor 15 receive commands from the host computer 30. The X-axis drive motor 5, through the coupling 4, drives the drive screw 14, and guide rails to form the X-axis group 2, the Y-axis group 21, and the Z-axis group 1, which are used to achieve horizontal free movement of the curved surface substrate 11 to be printed in the X, Y, and Z directions. The conformal printing module 3 in the support frame 10 performs linear motion in the X and Z directions, and the worktable 17 performs linear motion in the Y direction. The worktable 17 has a high-precision and firm mechanical fixture to fix the curved surface substrate 11 to be printed and is highly connected to the Y-axis group 21. The B-axis drive motor 23 for the two-dimensional turntable tilting action receives commands from the host computer 30 and drives the table to rotate about the Y axis. The C-axis drive motor 9 for the rotation action located on the two-dimensional turntable tilting action table receives commands from the host computer 30 and drives the rotation action table to rotate about the Z axis. These three linear motions and two rotational motions realize the motion function of five-axis linkage, which can perform direct printing of any complex curved surface circuit. In order to better adapt to and complete the requirements of complex curved surface electrofluid conformal printing, the rotation module 19 composed of the C rotation module 18 and the B rotation module 20 is provided with a grating scale sensor control limit around the Y and Z directions to limit the excessive movement of the B and C axes in the Y and Z axis directions, and eliminate the interference between the conformal printing module 3 or other components and the curved surface substrate 11 to be printed during the conformal printing of complex curved surface circuits. In addition, considering that the weight of the curved surface substrate 11 to be printed is large, in order to balance gravity and reduce the pressure of the motor drive, the B-axis drive motor 23 and the C-axis drive motor 9 are added with gravity sensors. At the same time, in order to ensure that the control of the rotational motion state is more accurate, the B-axis drive motor 23 and the C-axis drive motor 9 are added with attitude sensors to monitor their attitudes in real time and feed back the monitoring signals to the host computer 30 to form a more stable closed-loop control. The motor housing has a shielding function in terms of material to ensure that the internal motion electric signal has no effect on the external printing electric field. The workbench 17 is grounded to ensure that the curved surface substrate 11 to be printed is at zero potential.

[0035] Movement relationship Figure 3As shown, the object to be printed, i.e., the curved surface substrate 11, is mounted on a two-dimensional rotary table, i.e., a workbench 17. The first rotating portion of the two-dimensional rotary table can rotate about the Y axis (B-axis rotation), while the second rotating portion is mounted on the table surface of the first rotating portion and can rotate about a normal direction perpendicular to the plane of the first rotating portion (C-axis rotation). The two-dimensional rotary table is also mounted on a support structure that can perform left and right translational motion in the Y direction, and moves along the support structure in a linear motion 29 along the Y axis. The conformal printing module 3 is mounted on a base plate that can perform translational motion in the X and Z directions, and can simultaneously perform translational motion in a linear motion 26 along the X axis and a linear motion 25 along the Z axis. The relative motion between the object to be printed and the nozzle 7 achieves three translational motions in the X, Y, and Z directions, and two rotational motions in the B and C directions, 28 and 27. This results in a five-axis motion mechanism that enables the nozzle 7 to reach any curved surface position on the curved surface substrate 11 to be printed, while maintaining a reasonable printing distance, thus fulfilling the basic motion requirements of three-dimensional printing. A grating ruler is installed on each motion axis, and the upper computer 30 realizes closed-loop control of the motion axis through the position feedback of the grating ruler, so that the five-axis motion platform can realize vertical printing of the nozzle on the curved substrate to avoid the influence of the curved surface electric field.

[0036] 2) Adaptive printing module

[0037] The conformal printing module 3 includes a nozzle and an electrical signal supply unit. The nozzle is positioned below the Z-axis assembly 1 and moves with the Z-axis assembly 1. It includes an ink cartridge 16, a nozzle 7 positioned below the ink cartridge 16, and an auxiliary electrode ring 12 positioned below the nozzle. The electrical signal supply unit includes a function generator 31, an AC power supply 32, and a flow pump. Driven by the flow pump, ink in the ink cartridge is supplied to the nozzle 7 via a conduit. The function generator 31 is used to provide the required alternating voltage to the ink in the nozzle 7 and the electrode ring 12, generating various waveforms such as square waves, sine waves, and triangular waves. The voltage signal is amplified 1000 times by the function generator 31 and loaded between the nozzle 7 and the substrate, reaching the high-voltage range required for electro-jet printing. Electrical signals of different waveforms can cause the nozzle 7 to produce different forms of electro-fluidic jets. The workbench 17 is grounded, ensuring that the potential of the curved substrate 11 to be printed is zero. The voltage applied to the ink is higher than the voltage applied to the electrode ring 12, thereby creating a gradient potential difference between the ink, the electrode ring 12, and the curved substrate 11 to be printed. This ensures the stability of the electric field during the posture changes of the curved substrate 11 to be printed, and the liquid is precisely sprayed from the tip of the Taylor cone 33 onto the curved substrate 11 to be printed. Furthermore, the electrode ring 12 is coaxial with the nozzle 7 to reduce the voltage between the electrode ring 12 and the substrate, thereby reducing the impact of substrate polarization on the printing effect. The electrode ring 12 also serves to focus the jet, achieving the effect of suppressing satellite droplets.

[0038] The nozzle 7 in the form-fitting printing module 3 of the present invention is a slender tube structure, which is connected to the ink cartridge through a flow pump to inject ink while providing driving force; the diameter of the nozzle 7 is slightly larger than the nozzle diameter of a general inkjet printer, so as to ensure that the processing speed will not be reduced much; the inkjet method adopts two modes: on-demand inkjet and continuous inkjet; each time a nozzle is used to spray a circuit on the surface of the printed entity, the nozzle will use a pneumatic cylinder or other mechanical structure to ensure that it extends further than the other nozzles, thereby ensuring that the nozzle does not interfere with the surface of the printed entity, and can accurately print circuits in various shapes, especially relatively deep recessed parts can also be accurately sprayed; separate nozzles can be grouped into the same material nozzle according to specific needs to increase the printing speed, provided that the size of the nozzle group must meet the narrowest shape requirements of the printed entity surface. The ink cartridge 16 is used to store the ink to be printed. The function generator 31 applies a high alternating voltage to the conductive ink through the side wall of the nozzle 7 and applies a low voltage to the auxiliary electrode ring 12. Combined with the zero potential on the curved surface substrate 11 to be printed, a stable curved surface electric field is formed that has no effect on the motor module and does not change with the posture movement of the curved surface substrate 11 to be printed, thereby providing an electric field force for the conductive ink at the nozzle 7.

[0039] 3) Vision module

[0040] The vision module 6 is primarily used for benchmark alignment and real-time visual monitoring of the curved substrate 11 to be printed during the printhead spraying process. The positioning camera 13 ensures real-time and precise positioning between the curved substrate and the nozzle 7. At the start of printing, a special mark (typically a crosshair, but other shapes are also possible) is printed at a specific location. Simultaneously, an independent high-resolution camera captures the mark and, using image recognition technology, decomposes the deviations in the five degrees of freedom (X, Y, Z, B, and C). Based on these deviations, the five motion axes are controlled to perform corrections. Once corrections are complete, the curved circuit printing proceeds directly.

[0041] During the printing process, the observation camera 8 is used to observe the Taylor cone 33 of the electrospray jet in real time. By monitoring the jet morphology throughout the entire process, the liquid state at the tail of the nozzle 7 can be observed in real time, and the printing process parameters can be adjusted in a timely manner, thereby printing the required high-quality, high-precision curved circuit.

[0042] 4) Host computer control system

[0043] The host computer control system of an electrofluidic printing device for high-precision, complex, hard-curved surface conformal circuits is the core of the entire device. With the aforementioned five-axis linkage mechanical structure and conformal printing module 3, the host computer control system must closely integrate five-axis linkage motion control and printing control, while fully leveraging software advantages to achieve functions from three-dimensional curved surface modeling to solid motion trajectory planning, in order to achieve complete three-dimensional printing functionality. Therefore, the host computer control system must not only meet various requirements for real-time motion control and synchronous printing control, but also possess powerful motion trajectory planning capabilities. A control system that can simultaneously meet these requirements requires both strong real-time control capabilities and synchronous control capabilities, as well as strong capabilities for three-dimensional modeling processing, computer-aided design and computer-aided machining (CAD / CAM) processing, and other capabilities. Since most current three-dimensional modeling and CAD / CAM software runs on a multi-tasking operating system software platform, a control system suitable for this device must also have strong real-time control capabilities, that is, it must be based on a strong real-time operating system. Therefore, a single general-purpose operating system software platform cannot meet the requirements of this control system.

[0044] The host computer 30 of the present invention adopts a control system with a multi-general-purpose PC parallel processing structure, using multiple PCs to complete different tasks. The core structure is two PCs with general-purpose I / O boards, and the PCs achieve real-time data exchange through real-time data links to complete the parallel control tasks. The first PC runs on a general-purpose multi-tasking operating system software platform, mainly completing functions such as three-dimensional processing, motion trajectory planning, computer-aided design and auxiliary processing, human-computer interaction, and network communication. The second PC runs on a general-purpose strong real-time operating system software platform. By configuring different computer general bus multi-function boards, motion control boards, bus communication boards, and other controllers on this PC, different real-time motion control, printing control, and other auxiliary control functions are realized. The main functions are real-time motion control and real-time printing control, as well as synchronous control between the two, and online information processing. This structure fully utilizes the powerful functions of the general-purpose multi-tasking operating system software platform, such as three-dimensional processing, computer-aided design and auxiliary processing, human-computer interaction, and network communication, while simultaneously ensuring strong real-time control capabilities. Based on the core structure, it can be expanded to be equipped with more general-purpose PCs or servers to complete collaborative work through real-time or non-real-time data links.

[0045] Host computer 30 includes a three-axis motion control unit, a two-axis rotation control unit, and an electrical signal control unit, all highly integrated via a control card and software. This unit controls the coordinated motion of motion module 24 to achieve on-demand printing of circuits on complex curved surfaces. It also controls function generator 31 and a flow pump to provide electrical signals and flow to conformal printing module 3. By controlling these signals and flow, combined with the control of motion module 24, real-time, on-demand control of the printing process is achieved.

[0046] Example 2

[0047] The present invention also provides a method for electrofluid printing of high-precision complex hard surface conformal circuits. Figure 5 and Figure 6 This is a schematic diagram of the surface of the object to be printed constructed according to the present invention, which specifically includes the following steps:

[0048] 1. Clamp the curved surface substrate 11 to be printed on the workbench 17;

[0049] 2. Import the 3D model of the curved surface substrate 11 to be printed into the 3D software, and plan the layout and placement of the curved surface space according to the selected electronic components;

[0050] 3. Import the PCB wiring diagram of the planar functional circuit into the 3D software and map it onto the surface of the 3D curved substrate according to the curved space planning;

[0051] 4. Perform CAM path process planning on the mapped curved surface circuit, and save the motion trajectory position information data of the conformal printing of the curved surface circuit according to the printing sequence. The motion trajectory position information includes the spatial coordinate values ​​of the printing point and the rotation coordinate value to ensure that the printing normal is perpendicular to the surface of the curved surface substrate 11 to be printed. Next, use the CAM software and post-processing module in the control system to generate a five-axis linkage machining trajectory code program;

[0052] 5. The generated processing code data is integrated through software and sent to the host computer 30 for analysis;

[0053] 6. The host computer 30 controls the coordinated movement of the X-axis group 2, the Y-axis 21, the Z-axis 1, and the rotation module 19 according to the content of the analyzed data, and controls the switch and size of the function generator 31 and the precision flow pump as needed to achieve real-time control. Specifically, the host computer 30 motion control software is used to perform interpolation operations, tool compensation, acceleration and deceleration control algorithms according to the five-axis motion trajectory code file, and output control instructions for the five axes X, Y, Z, B, and C, respectively driving the drive motors connected to the five axes X, Y, Z, B, and C to move. The curved surface substrate 11 to be printed is installed on a two-dimensional rotary table. The first rotating part of the two-dimensional rotary table can rotate around the Y axis (B-axis rotation), and the second rotating part is installed on the table surface of the first rotating part. The second rotating part can rotate around the normal direction perpendicular to the plane of the first rotating part (C-axis rotation); the two-dimensional turntable is also installed on the support structure for Y-axis translation, and moves forward and backward along the Y direction with the support structure; the nozzle part is installed on a bracket that can make X- and Z-direction translation movements, and can make X- and Z-direction translation movements at the same time. Through the relative movement of the curved surface substrate 11 to be printed and the nozzle 7, three translational movements of X, Y, and Z and two rotational movements of B and C are realized, thereby realizing a five-axis linkage motion mechanical structure, further enabling the nozzle of the print head to reach any curved surface position on the printed entity and maintain a reasonable printing distance, realizing the basic motion requirements of three-dimensional stereoscopic printing; at the same time, the conformable printing module 3 working in parallel performs inkjet printing according to the three-dimensional circuit processing data file of the curved surface substrate, and performs inkjet printing with the nozzle 7 controlled synchronously with the five-axis motion.

[0054] Example 3

[0055] The present invention targets the surfaces of hard objects with complex shapes, breaks through the bottleneck of traditional electronic circuit technology's restrictions on curved patterns, completes the upgrade of circuit manufacturing from plane to three-dimensional, and realizes the direct conformal printing of complex circuits on any curved surface; secondly, a flow pump is used to drive the ink in the ink cartridge 16 to prevent the "needle climbing" phenomenon of ink caused by capillary effect, thereby achieving a quantitative and stable supply of functional materials throughout the printing process; the curved surface electric field will interfere with the electro-fluid printing jet, so an electrode ring 12 is integrated directly below the nozzle 7 of the nozzle to solve the problem of uneven electric field caused by the unequal distance between the curved substrate and the nozzle, and the voltage is directly applied to the nozzle and the printing platform in this state, forming a stable electric field to improve the stability, uniformity and accuracy of the conformal printing process; a set of real-time monitoring system for the printing process has been established, which can realize the monitoring of the jet morphology during the entire printing process. By observing the liquid state at the tail of the nozzle 7 in real time, the printing process parameters can be adjusted in time, thereby printing the required high-quality, high-precision curved circuits. Specifically:

[0056] 1) The present invention can effectively solve the current technical problem in the field of printed electronics that is unable to directly manufacture high-precision circuits on the surface of complex product structures. It can realize the automated, precise, environmentally friendly and high-efficiency direct manufacturing of conformal circuits on arbitrarily complex curved surfaces without the need for other additional auxiliary processes such as transfer and deformation.

[0057] 2) The present invention can directly manufacture curved circuits on the surface of products of any complex shape, breaking through the limitations of printing conditions and resolution in traditional printing processes. It has the advantages of simple process, high resolution, high efficiency, high reliability and low cost.

[0058] 3) The present invention has the advantages of short cycle, high printing precision, no shape restriction, miniaturization, lightweight, intelligence and personalization, breaking through the technical bottleneck of the transformation of electronic circuit manufacturing technology from plane to three-dimensional, and meeting the flexibility requirements of direct manufacturing of conformal circuits on arbitrary curved surfaces.

[0059] 4) The present invention uses a function generator 31 to apply a high voltage to the conductive ink, applies a low voltage to the electrode ring 12, and grounds the workbench 17 to make the potential on the curved surface substrate 11 to be printed zero, thereby forming a stable electric field that has no effect on the motor module and does not change with the posture movement of the curved surface substrate to be printed, so that the conductive ink at the nozzle 7 can be sprayed smoothly and continuously, with high printing accuracy and good forming effect.

[0060] 5) The present invention uses electrofluidic printing to prepare curved surface conformal electronics, which reduces manufacturing costs, expands the application range of printable materials, and improves printing accuracy. The use of a five-degree-of-freedom motion platform can ensure that the normal of the surface to be printed is always coincident with the direction of the nozzle. Assisted by the matching of the function and parameter setting of the electrode ring 12, a stable electrofluid printing process environment can be provided to ensure the stable formation and maintenance of the "Taylor cone" during the electrofluid printing process; combined with the printing method in the present invention, a conformal patterning process for arbitrarily complex surfaces can be realized, and high-quality circuits and devices with high straightness, good uniformity, strong continuity and excellent electrical performance can be prepared by direct printing, breaking through the technical bottleneck of not being able to directly manufacture high-precision conformal circuits on arbitrarily complex surfaces (especially concave surfaces with large curvature), breaking the limitation that traditional curved surface electronics preparation is limited to preparation on simple surfaces or planes with small curvature, and improving the application range of electrofluid conformal printing technology.

[0061] 6) The present invention uses a five-degree-of-freedom motion platform that combines a three-axis motion platform with a two-axis rotation for collaborative control. Position coordinate information can be directly input into the motion control system, thereby improving the efficiency of motion trajectory analysis.

[0062] 7) The present invention adds an electrode ring 12 under the nozzle, which is used to focus the jet and suppress satellite droplets, and is also used to generate a gradient potential difference between the nozzle 7 and the electrode ring 12, and between the electrode ring 12 and the curved surface substrate 11 to be printed, thereby ensuring a stable curved surface electric field for injection and preventing the occurrence of a disordered electric field caused by rotational posture adjustment and potential interference of the curved surface substrate.

[0063] 8) The present invention addresses the situation where an electrofluidic printing jet often cannot be generated when printing on a curved insulating substrate, or jet turbulence occurs due to strong electric field polarization. By improving the nozzle of the curved electrofluidic printing, a function generator 31 is configured with a positive and negative alternating electric field, so that the electrofluidic printing process can directly print high-precision conformal circuits on demand on any substrate, ensuring that the morphology of the deposited droplets and the jet trajectory are not affected by the substrate material.

[0064] 9) The present invention addresses the phenomenon of "needle creeping" caused by the accumulation of silver conductive ink at the tip of the nozzle, and achieves a constant and stable supply of functional materials throughout the entire printing process through the drive of a flow pump.

[0065] 10) The present invention establishes a real-time monitoring system for the printing process, which can monitor the jet morphology throughout the printing process. By observing the liquid state at the tail of the nozzle 7 in real time, the printing process parameters can be adjusted in a timely manner, thereby printing the desired high-quality, high-precision curved circuit.

Claims

1. High-precision, complex, hard-curved surface conformal circuit electro-fluid printing equipment, characterized by: The invention comprises a support frame (10), wherein a Y motion axis group (21) is provided in the support frame (10), a support structure for translational motion along the Y axis is provided on the Y motion axis group (21), a B rotation module (20) for rotational motion around the Y axis is supported on the support structure, a C rotation module (18) for rotational motion around the Z axis is provided on the B rotation module (20), a workbench (17) is provided on the C rotation module (18), an X motion axis group (2) is provided on the top of the support frame (10), one end of the X motion axis group (2) is connected to a Z motion axis group (1) for translational motion along the X axis, a shape-adaptive printing module (3) and a visual module (6) for translational motion along the Z axis are provided at the bottom end of the Z motion axis group (1) corresponding to the workbench (17), and the shape-adaptive printing module (3) and the visual module (6) are electrically connected to a host computer (30) in common. The form-fitting printing module (3) includes an ink cartridge (16), a flow pump electrically connected to a host computer (30) is connected to the ink cartridge (16) via a pipeline, a nozzle (7) with its bottom facing downward is fixedly connected to the bottom of the ink cartridge (16) via a conduit, an electrode ring (12) is coaxially spaced below the nozzle (7), and the outer wall of the electrode ring (12) and the nozzle (7) are electrically connected in sequence to a function generator (31) electrically connected to the host computer (30) and a grounded AC power supply (32); A Y-axis drive motor (22) electrically connected to the host computer (30) is provided at one end of the Y-axis motion axis group (21), the Y-axis drive motor (22) being provided with a grating ruler electrically connected to the host computer (30), and an output end of the Y-axis drive motor (22) being coaxially connected to a lead screw passing through the support structure and threadedly engaged with the support structure through a coupling; One end of the B rotation module (20) is fixedly connected to a B-axis drive motor (23) electrically connected to the host computer (30) along the Y axis, and the B-axis drive motor (23) is provided with a grating ruler, a gravity sensor, and a posture sensor, all of which are electrically connected to the host computer (30); A C-axis drive motor (9) located on the B-axis drive module (20) and electrically connected to the host computer (30) is fixedly connected to the C-axis drive module (18) along the Z axis. The C-axis drive motor (9) is provided with a grating ruler, a gravity sensor, and a posture sensor, all of which are electrically connected to the host computer (30). An X-axis drive motor (5) electrically connected to the host computer (30) is provided on one side of the X-axis motion axis group (2), and a grating ruler electrically connected to the host computer (30) is provided on the X-axis drive motor (5). The output end of the X-axis drive motor (5) is coaxially connected to a lead screw (14) passing through the Z-axis motion axis group (1) and threadedly engaged with the lead screw (14) through a coupling (4); A Z-axis drive motor (15) electrically connected to the host computer (30) is provided along the Z-axis at the top of the Z-axis motion axis group (1), a grating ruler electrically connected to the host computer (30) is provided on the Z-axis drive motor (15), and an output end of the Z-axis drive motor (15) is coaxially connected to a lead screw that passes through a base plate that fixes the form-fitting printing module (3) and the vision module (6) and is threadedly engaged with the base plate through a coupling.

2. The electrofluidic printing device for high-precision, complex, hard-curved conformal circuits according to claim 1, characterized in that: The visual module (6) includes a positioning camera (13) and an observation camera (8) located on both sides of the ink cartridge (16) and electrically connected to the host computer (30), wherein the positioning camera (13) is perpendicular to the curved surface substrate (11) to be printed, and the observation camera (8) is aligned with the nozzle (7).

3. The electrohydrodynamic printing method of the electrohydrodynamic printing device for high-precision complex hard-surface conformal circuit according to claim 1, characterized in that: The following steps are involved: Step 1: Create a three-dimensional model of the curved surface substrate (11) to be printed, import the required printed circuit and the corresponding process state requirements into the three-dimensional model, and plan the layout and placement of the curved surface space according to the selection of electronic components, and then place the curved surface substrate (11) to be printed on the workbench (17); Step 2: directly three-dimensionally map the planar circuit onto the surface to be printed of the three-dimensional model, and perform CAM path process planning on the mapped surface circuit; specifically: decompose the mapped surface circuit into multiple line segments and set a printing trajectory sequence for each line segment, discretize each line segment into multiple discrete points, and combine the position of the surface substrate to be printed (11) on the workbench (17) to obtain the five-degree-of-freedom motion trajectory position and process state requirements of each discrete point, wherein the motion trajectory position includes the X-axis, Y-axis and Z-axis and the rotation coordinates around the Y-axis and Z-axis; The process state requirements include the voltage applied by the function generator (31) and the flow rate of the flow pump controlling the nozzle (7); Step 3: The motion trajectory position and process state requirements of the discrete points are parsed into instructions of the host computer. The host computer prints in sequence according to the printing trajectory, thereby completing the conformal printing of the required printed circuit on the surface of the curved substrate (11) to be printed.

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