Electrohydrodynamic printing device and method for micro-spacing side wall electrode

Abstract

The invention relates to an electrohydrodynamic printing device for a micro-spacing side wall electrode. The electrohydrodynamic printing device comprises a precise motion platform, a multifunctional integrated printing module, a quality detection module, an electric field generation module and a visual positioning control system, the multifunctional integrated printing module comprises a rigid supporting arm, a combined spray needle and an angle-adjustable mounting seat; the combined spray needle is a concentric sleeve composed of an inner pipe and an outer pipe, the inner pipe is a main ink cavity, an annular area between the inner pipe and the outer pipe is divided into four independent cavities, the upper side and the lower side of the main ink cavity are induction solvent cavities, and the left side and the right side of the main ink cavity are recovery cavities. The induction solvent cavity conveys an induction solvent; the recycling cavity is used for recycling printing waste liquid; the quality detection module comprises a microprobe, and the microprobe can be in contact with a detection object in the detection process. According to the invention, the phenomenon of'tape casting 'of the electrode caused by vertical printing is fundamentally eliminated, and the interference of an edge electric field in a micro-spacing environment is effectively avoided, so that the high-quality side wall electrode with uniform macroscopic morphology and no short circuit can be prepared.

Description

Technical Field

[0001] This invention belongs to the field of high-end ultrasonic probe precision manufacturing technology, specifically a hydrodynamic printing device and method for micro-pitch sidewall electrodes. Background Technology

[0002] In manufacturing high-performance ultrasonic phased array probes, metal electrodes need to be fabricated on the sidewalls with micrometer-level spacing (e.g., <800μm) between piezoelectric elements. Traditional vertical printing causes a casting effect. When the nozzle prints vertically downwards, gravity is parallel to the sidewall. Not only are ink droplets stretched downwards due to gravity during ink ejection, but uncured ink printed on the side surface also flows downwards, resulting in electrodes that are "thin at the top and thick at the bottom" and "uneven linewidth," severely compromising the consistency of the probe's electroacoustic performance. Furthermore, in such a narrow space, the edge electric field generated by the electrodes of adjacent elements can severely interfere with and deflect the printing jet, leading to skewed printing paths, short circuits between adjacent electrodes, and extremely low yield. Traditional techniques such as photolithography and other planar processes are difficult to achieve uniform processing on deep and narrow sidewalls, with cumbersome steps, high costs, and poor results. Some printing methods require bending nozzles, which not only easily clog the nozzles at the bends but also cannot be used in micro-pitch environments due to the limitations of the bending dimensions. Traditional technologies are all "open-loop" processes, measuring electrode resistance values ​​only after printing. They lack the ability to monitor quality and perform immediate repairs during the printing process, meaning defects can only be detected during final inspection, resulting in wasted materials and time. Horizontal printing also requires addressing the unevenness of the printed electrode film caused by the coffee ring effect to avoid affecting the performance of the ultrasonic probe.

[0003] Coffee ring effect: Evaporation occurs fastest at the edge of the droplet (the triple line in contact with air and the tabletop). Evaporation leads to water loss, and to replenish this loss, a micro-flow occurs within the liquid, moving from the center of the droplet towards the edge. Coffee particles (or the silver nanoparticles described in this application) in the water are also carried along by this flow, continuously transported to the edge. Once the water has completely evaporated, the particles accumulate at the edge. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the technical problem this invention aims to solve is to provide an electrohydrodynamic printing device and method for micro-pitch sidewall electrodes.

[0005] The technical solution adopted by the present invention to solve the aforementioned technical problem is as follows: In a first aspect, the present invention provides an electrohydrodynamic printing device for micro-pitch sidewall electrodes, comprising a precision motion platform, a multi-functional integrated printing module, a quality detection module, an electric field generation module, and a vision positioning control system; The precision motion platform is used to provide nanometer-level precision motion in the X, Y, and Z directions for the piezoelectric array substrate fixed on it to be processed. The multi-functional integrated printing module includes a rigid support arm 7 for horizontal feeding, a combined nozzle 5, and an angle-adjustable mounting base for adjusting and locking the combined nozzle's spray angle. The combined nozzle 5 uses a concentric sleeve composed of an inner tube and an outer tube. The inner tube has a main ink chamber 18 inside, and the annular area between the inner and outer tubes is divided into 4 independent chambers. The annular areas on the upper and lower sides of the main ink chamber are solvent induction chambers 17, and the annular areas on the left and right sides of the main ink chamber are recovery chambers 19. The main ink chamber 18 is connected to an external main ink precision injection pump 9 via the main ink delivery pipe 21 to provide printing ink for printing; the induction solvent chamber 17 is connected to an external induction solvent precision injection pump 11 via the induction solvent delivery pipe 20 to deliver induction solvent with low surface tension; the recovery chamber 19 is connected to an external negative pressure pump 10 via the recovery pipe 22 to recover printing waste liquid. The outer wall of the combined nozzle is symmetrically provided with long grooves for mounting micro probes on both the left and right sides along its length. The quality inspection module is used for in-situ detection of electrode resistance and includes a microprobe and an impedance analyzer. One end of the microprobe is slidably installed in the long groove, and the other end of the microprobe is tilted downward. The lowest point of the microprobe is lower than the lower end of the outer wall of the combined spray needle and can contact the object being tested during the detection process. The microprobe is electrically connected to the impedance analyzer. The electric field generation module includes a high-voltage DC power supply 8, which is used to form a stable electric field between the combined nozzle and the lower substrate of the piezoelectric array substrate to be processed. The vision positioning control system is used to identify the positions of the piezoelectric array substrate to be processed and to assist in the positioning of the front end of the combined nozzle.

[0006] Furthermore, the positive terminal of the high-voltage DC power supply is connected to the metal outer wall of the combined spray needle 5 through a wire, continuously supplying positive charge to the combined spray needle, exciting induction to induce negative charge on the lower substrate of the piezoelectric element array substrate at the processing position, forming a self-induced electric field, thereby forming a stable induced electric field between the tip of the combined spray needle and the substrate. The angle-adjustable mounting base, quality inspection module, main ink precision injection pump, negative pressure pump, induction solvent precision injection pump, electric field generation module, and precision motion platform are all electrically connected to the vision positioning control system.

[0007] Furthermore, the device delivers a low surface tension inducing solvent to the printing site through the inducing solvent chambers 17 on both sides of the combined nozzle 5, causing the printing ink delivered by the main ink chamber to flow from both sides to the center, pulling the particles back from the edges and dispersing them evenly. The controlled Malagoni effect is used to suppress coffee rings, ensuring uniform microfilm formation. At the same time, the microprobe 15 measures the electrical impedance of the printed section online, and judges the electrode quality in real time based on the measurement data. If a defect is found, a self-healing program is triggered, controlling the combined nozzle 5 to return for a second printing at a fixed point. In addition, residual printing waste liquid can be collected through the left and right recovery chambers 19 before and after printing.

[0008] Furthermore, the precision motion platform unit includes a three-dimensional precision electric translation stage 1, a base, and a vacuum chuck clamp 3. The three-dimensional precision electric translation stage is fixed to the base by bolts and is used to provide nanometer-level precision motion in the X, Y, and Z directions. The vacuum chuck clamp 3 is mounted on the three-dimensional precision electric translation stage and moves with the three-dimensional precision electric translation stage to adsorb and fix the piezoelectric array substrate 4 to be processed.

[0009] Furthermore, the angle-adjustable mounting base 6 has a precision scale to ensure that the combined spray needle can be accurately deflected and locked within the range of 0°-90°.

[0010] Furthermore, the combined nozzle 5 includes a slender annular column and a connecting component. The slender annular column is cylindrical in shape and is made of a corrosion-resistant metal material with a smooth inner wall that does not chemically react with the ink. It has an annular cavity inside, and the ratio of the inner and outer ring radii of the slender annular column is 1:1.5~3. Baffles are symmetrically arranged on the left and right sides along the outer wall of the inner ring inside the annular cavity, dividing the annular cavity into two symmetrical recovery chambers 19 and two symmetrically arranged solvent induction chambers 17. The inner area of ​​the inner ring is the main ink chamber 18. The connecting component is a flat cylindrical shape, and its exterior is used to connect with the angle-adjustable mounting base. The connecting component is provided with a circuit that connects the upper and lower induction solvent chambers and converges into the induction solvent delivery pipeline, and a circuit that connects the left and right recovery chambers and converges into the recovery pipeline, near the slender cylindrical ring. The outer diameter of the combined spray needle 5 is 100~150μm, and the spacing between the upper and lower substrates of the piezoelectric array substrate to be processed is the outer diameter of the combined spray needle, and the spacing is 150μm~1mm. The rigid support arm is shaped like a "7" and includes a horizontal section and a vertical section. One end of the vertical section is fixed to the base of the precision motion platform, and the other end is connected to the horizontal section. The horizontal section is set parallel to the upper and lower substrates of the piezoelectric array substrate to be processed.

[0011] Secondly, the present invention provides a hydrodynamic printing method for micro-pitch sidewall electrodes, using the aforementioned apparatus, the method comprising the following steps: Step 1 Positioning: Fix the piezoelectric array substrate 4 to be processed on a precision motion platform, which can adjust the three-dimensional spatial position of the piezoelectric array substrate. The precision motion platform is adjusted so that the combined nozzles are fed horizontally into the space between the adjacent upper substrate 14 and lower substrate 16 of the piezoelectric element array substrate. The distance between the upper and lower substrates is within 1mm. The printing path is planned, and then the combined nozzles 5 are deflected to the optimal angle by the angle-adjustable mounting base 6 to complete the printing positioning. The second step begins printing: The high-voltage DC power supply 8 is turned on, applying a DC voltage of 800-1500 V; the negative pressure pump 10 is turned off, and the main ink precision injection pump 9 is turned on, supplying conductive ink at a rate of 1-9 μL / min. Under the action of the electric field, the ink forms a stable liquid bridge; simultaneously, the three-dimensional precision electric translation stage 1, controlling the precision motion platform, moves the substrate uniformly along the X-axis at a speed of 1-9 mm / s; 0.05-0.2 s after printing begins, the induction solvent precision injection pump 11 is turned on, releasing 0.5-1 μL of induction solvent; the surface tension of the induction solvent is lower than that of the main ink. The solvent spreads on the surface of the liquid bridge, promoting a smooth liquid film through the Malagoni effect; After printing is completed, the negative pressure pump 10 is turned on to recover the solution that has accumulated at the ink outlet of the combined nozzle 5 through the recovery chamber 19, so as to prevent dripping. The third step is detection and repair: After printing the sidewall of an array element, the platform pauses; the visual positioning control system controls the impedance analyzer 12 to work, and uses the micro probe 15 to measure the impedance of the newly printed electrode, obtaining the impedance value Z; the measured impedance value Z is compared with the preset qualified threshold [Z_min, Z_max]; if it is within the preset qualified threshold, the electrode quality is determined to be qualified, and the system continues to print the next array element; Z_min and Z_max are the lower limit and upper limit of the qualified threshold, respectively; If Z exceeds the acceptable threshold range, there are pores, cracks, or unevenness. The system immediately executes the self-healing subroutine; records the current position coordinates that exceed the acceptable threshold range, controls the three-dimensional precision electric translation stage 1 of the precision motion platform to return the combined nozzle 5 to the position coordinates, applies voltage again and turns on the main ink injection pump and the induction solvent injection pump to perform a fixed-point, quantitative secondary printing to repair the defects. After repair, measure the impedance again. If the impedance value returns to normal, continue with the subsequent process; if it is still abnormal, repeat the steps until the repair is successful. Step 4: Spacing Adjustment: When the spacing or aspect ratio between adjacent upper and lower substrates to be printed on the piezoelectric array substrate changes, the angle of the combined nozzles, the voltage of the high-voltage DC power supply, the feed amount of printing ink and inducing solvent, and the printing speed are adjusted by using the angle-adjustable mounting base to adapt to array structures with different spacing and aspect ratios.

[0012] Furthermore, the method includes: Set the normal printing volume of the main nozzle and the inducing solvent, and obtain data on printing speed, ink feed volume, inducing solvent feed volume, and voltage of high voltage DC power supply when establishing array structures with different spacing and aspect ratios to meet surface roughness requirements and impedance detection requirements. Establish a model relating the spacing, aspect ratio, printing speed, ink feed rate, induction solvent feed rate, and voltage; When the visual positioning control system detects changes in spacing and aspect ratio, it automatically adjusts the printing speed, ink feed rate, induction solvent feed rate, and voltage using the aforementioned relationship model.

[0013] Furthermore, the process of determining the quantitative repair is as follows: the total amount of main ink and inducing solvent is recorded as the repair amount. The specific value of the repair amount is related to the detected impedance abnormality, i.e., the magnitude of the Z value deviating from the threshold. The deviation ratio is calculated according to (Z-Z_max) / Z_max. The deviation ratio is used as the proportion of the repair amount to the normal printing amount. The fixed-point quantitative repair is completed with the determined repair amount. Continuous flow is not used during repair. Instead, the pulse mode of the main ink precision injection pump 9 and the inducing solvent precision injection pump is used for repair.

[0014] Furthermore, the surface roughness of the printed electrode was measured using an AFM atomic force microscope, and the impedance value was detected using an impedance analyzer.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention fundamentally eliminates the electrode "dragging" phenomenon caused by vertical printing by adopting a horizontal near-field printing posture, and effectively avoids edge electric field interference in a micro-pitch environment, thereby enabling the fabrication of high-quality sidewall electrodes with uniform macroscopic morphology and no short circuits.

[0016] 2. This invention introduces an independently controllable inducing solvent to stimulate the Malagoni effect, and uses the resulting reverse fluid to precisely counteract the capillary flow that causes the "coffee rings," thereby achieving ultra-uniform flatness of the electrode film at the microscopic level and ensuring the consistency of electrical performance.

[0017] 3. This invention integrates an impedance monitoring and self-healing closed-loop system, which can detect and repair micro-defects in real time during the printing process, upgrading the manufacturing process from open-loop to closed-loop, thereby reducing manufacturing defects of micro-pitch electrodes and significantly improving product yield.

[0018] 4. This invention integrates printing, monitoring, and repair functions through modularization, and through unified control, a single system can adapt to various array structures with different spacing and aspect ratios, significantly improving process flexibility and production efficiency while reducing equipment and process costs. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the electrohydrodynamic printing device for micro-pitch sidewall electrodes of the present invention.

[0020] Figure 2 This is a partially enlarged schematic diagram of the combined nozzle connection portion according to an embodiment of the present invention.

[0021] Figure 3 This is a schematic diagram of the overall structure of the combined spray needle according to an embodiment of the present invention.

[0022] Figure 4 This is a schematic diagram showing the micro-pitch printing position of the combined nozzles on the upper and lower substrates of the piezoelectric element array substrate according to an embodiment of the present invention.

[0023] Figure 5 This is a schematic diagram of the connecting component in the combined spray nozzle of the present invention.

[0024] Figure 6 This is a schematic flowchart of a printing method according to an embodiment of the present invention. Figure 7 This is a schematic diagram illustrating the effects of the coffee ring effect and the Malagoni effect on the flow of silver nanoparticles.

[0025] In the figure, 1 is a 3D precision electric translation stage, 2 is a high-resolution CCD camera, 3 is a vacuum chuck fixture, 4 is a piezoelectric array substrate, 5 is a combined nozzle, 6 is an angle-adjustable mounting base, 7 is a rigid support arm, 8 is a high-voltage DC power supply, 9 is a precision injection pump for main ink, 10 is a negative pressure pump, 11 is a precision injection pump for inducing solvent, 12 is an impedance analyzer, 13 is a computer, 14 is an upper substrate, 15 is a microprobe, 16 is a lower substrate, 17 is an inducing solvent chamber, 18 is a main ink chamber, 19 is a recovery chamber, 20 is an inducing solvent delivery pipe, 21 is a main ink delivery pipe, 22 is a recovery pipe, 23 is the flow direction of coffee ring effect particles, 24 is the flow direction of Malagoni effect particles, and 25 is a nano silver particle. Detailed Implementation

[0026] The present invention will be further explained below with reference to the embodiments and accompanying drawings, but this is not intended to limit the scope of protection of this application.

[0027] This invention relates to an electrohydrodynamic printing device and method for micro-pitch sidewall electrodes. It employs a horizontal near-field printing posture and horizontal feed to avoid macroscopic casting and electric field interference. Low surface tension inducing solvent is delivered to the printing site through induction solvent chambers 17 on both sides of the combined nozzle 5, utilizing the controlled Malagoni effect to suppress coffee rings and ensure uniform microfilm formation. Simultaneously, an integrated microprobe 15 measures the electrical impedance of the printed section online, judging the electrode quality in real time based on the measurement data. If defects are detected, a self-healing program is triggered, controlling the combined nozzle 5 to return for a second, targeted printing. Furthermore, residual printing waste liquid can be collected through the left and right side recovery chambers 19 before and after printing.

[0028] The core of the Malagoni effect is that liquids spontaneously flow from areas of low surface tension to areas of high surface tension. By releasing a low-surface-tension solution on the outside of the printing ink, the ink flows from both sides towards the center, pulling particles back from the edges and dispersing them evenly.

[0029] Figure 7 This diagram illustrates the effects of the coffee ring effect and the Malagoni effect on the flow of silver nanoparticles. In the diagram, 23 represents the flow direction of particles with the coffee ring effect, 24 represents the flow direction of particles with the Malagoni effect, and 25 represents silver nanoparticles. The Malagoni effect suppresses the coffee ring effect.

[0030] This invention employs a "self-inductive coupling" method, connecting only the positive terminal of the high-voltage power supply to the combined nozzle, without physically connecting the negative terminal. The high voltage of the combined nozzle induces a negative charge on the substrate, thereby creating a stable induced electric field between the nozzle tip and the substrate. This method significantly reduces the risk of excessive current and damage to the printed micro-electrodes due to misoperation in micro-pitch environments, thus improving process safety.

[0031] In this invention, the main body of the combined nozzle feeding part is made of a corrosion-resistant metal material with a smooth inner wall that does not chemically react with the ink, such as stainless steel, and the related delivery pipe can be made of a flexible hose.

[0032] Example 1: This embodiment is used for an electrohydrodynamic printing device for micro-pitch sidewall electrodes, such as... Figure 1 As shown, it mainly includes a precision motion platform, a multi-functional integrated printing module, a quality inspection module, an electric field generation module, and a vision positioning control system.

[0033] The precision motion platform unit consists of a three-dimensional precision electric translation stage 1 and a vacuum chuck fixture 3. The three-dimensional precision electric translation stage is fixed to the base by bolts and is used to provide nanometer-level precision motion in the X, Y, and Z directions. The vacuum chuck fixture 3 is mounted on the three-dimensional precision electric translation stage 1 and can move with the three-dimensional precision electric translation stage to adsorb and fix the piezoelectric array substrate 4 to be processed.

[0034] The multi-functional integrated printhead module is the core of the device of this invention, including a rigid support arm 7, a combined nozzle 5, and an angle-adjustable mounting base 6. The rigid support arm 7 is fixed to the equipment frame, and its end is connected to the combined nozzle 5 through the angle-adjustable mounting base 6. The angle-adjustable mounting base 6 has a precise scale to ensure that the printhead can be accurately deflected and locked within the range of 0°-90°. The specific structure and adjustment method of the angle-adjustable mounting base 6 can be achieved through existing technology. The combined nozzle 5 includes a slender cylindrical column and a connecting component. The slender cylindrical column is cylindrical in shape and has an annular cavity inside. The ratio of the inner and outer ring radii of the slender cylindrical column is 1:2~3. Within the annular cavity, partitions are symmetrically arranged along the outer wall of the inner ring, dividing the annular cavity into two symmetrically arranged recovery chambers 19 and two symmetrically arranged solvent-inducing chambers 17. The inner area of ​​the inner ring is the main ink chamber 18. The front end of the slender cylindrical column is the tip of the combined nozzle (i.e., the ink outlet end).

[0035] The main ink chamber 18 of the combined nozzle 5 is connected to an external main ink precision injection pump 9 via a main ink delivery pipe 21 to provide nano-silver ink for printing. The induction solvent chamber 17 is connected to an external induction solvent precision injection pump 11 via an induction solvent delivery pipe 20 to deliver a low surface tension induction solvent. The recovery chamber 19 is connected to an external negative pressure pump 10 via a recovery pipe 22. In non-printing states, the negative pressure pump 10 can generate negative pressure to recover printing waste liquid and prevent liquid leakage.

[0036] The quality detection module is highly integrated with the combined spray needle 5 to achieve in-situ detection. Two microprobes 15 are slidably fixed on the combined spray needle 5, and can be slidably adjusted along the X-axis on the outer wall of the combined spray needle 5 to finely adjust the detection angle. The impedance analyzer 12 is connected to the microprobes 15 and is used to apply test signals and measure the impedance value of the electrodes.

[0037] The outer wall of the combined nozzle is symmetrically slotted along its length. Detection is performed before and after the combined nozzle moves horizontally. The slotted positions on the surface can also be used for wiring to electrically connect with external micro probes.

[0038] When the angle of the combined nozzles changes, the microprobe can be adjusted to adapt to the change in the combined nozzle angle. One end of the microprobe is slidably connected to the slot, and the lower end of the microprobe can contact the ink on the substrate. After printing, a complete electrode that meets the surface requirements can be obtained by high-temperature sintering.

[0039] In this embodiment, the outer diameter of the combined nozzle 5 is 120 μm, the inner diameter is 60 μm, and the substrate spacing of the piezoelectric array substrate is greater than 120 μm.

[0040] The electric field generation module includes a high-voltage DC power supply 8. Its positive terminal is connected to the slender annular column of the combined nozzle 5 via a wire. The slender annular column is made of stainless steel. By exciting self-induction, it induces a negative charge on the substrate of the piezoelectric element array, thereby forming a stable electric field between the combined nozzle 5 and the substrate 16 of the piezoelectric element array.

[0041] The visual positioning control system includes a high-resolution CCD camera 2 and a computer 13. The high-resolution CCD camera 2 is mounted on one side and is used to identify the positions of the piezoelectric element array substrate and assist in the positioning of the print head. The computer 13 controls the three-dimensional precision electric translation stage 1, the main ink precision injection pump 9, the negative pressure pump 10, the induction solvent precision injection pump 11, the impedance analyzer 12, the angle-adjustable mounting base 6, the high-voltage DC power supply 8, and the high-resolution CCD camera 2 to perform corresponding actions.

[0042] Example 2: This embodiment uses a hydrodynamic printing method for micro-pitch sidewall electrodes (see [link]). Figure 6 ), including the following steps: Step 1 Positioning: The piezoelectric element array substrate 4 (made of piezoelectric ceramic material, exhibiting piezoelectric effect) is placed on the vacuum chuck clamp 3 and fixed by vacuuming. Controlled by the vision positioning control system, the three-dimensional precision electric translation stage is adjusted so that the combined nozzles can be fed horizontally between the upper substrate 14 and the lower substrate 16 of the piezoelectric element array substrate. The distance between the two substrates is less than 1mm. The printing path is planned, and then the combined nozzles 5 (including the main nozzle (main ink chamber) and the auxiliary nozzle (inducing solvent chamber)) are deflected to the optimal angle by the angle-adjustable mounting base 6 to complete the printing positioning.

[0043] The second step is to begin printing: Turn on the high-voltage DC power supply 8, applying a DC voltage of 800-1500 V. Turn off the negative pressure pump 10 and turn on the main ink precision injection pump 9, supplying conductive ink at a rate of 1-9 μL / min. The ink forms a stable liquid bridge under the action of the electric field. Simultaneously, control the three-dimensional precision electric translation stage 1 to move the piezoelectric array substrate at a constant speed of 1-9 mm / s along the X-axis. 0.05-0.2 s after printing begins, turn on the induction solvent precision injection pump 11, releasing 0.5-1 μL of induction solvent (such as ethanol). The surface tension of the induction solvent is lower than that of the main ink. The solvent spreads on the surface of the liquid bridge, promoting a smooth liquid film through the Malagoni effect. After printing is complete, turn on the negative pressure pump 10 to recover the solution accumulated at the ink outlet of the combined nozzle 5 through the recovery chamber 19, preventing dripping.

[0044] Step 3: Inspection and Repair: After printing the sidewall of one array element, the platform pauses. Computer 13 controls impedance analyzer 12 to measure the impedance of the newly printed electrode using microprobe 15, obtaining the impedance value Z. The measured impedance value Z is compared with preset acceptable thresholds [Z_min, Z_max]. If the electrode quality is deemed acceptable, the system continues printing the next array element.

[0045] If Z exceeds the acceptable threshold range, there are defects such as pores or cracks, or unevenness at that location (generally, only cases where Z exceeds the upper limit of the acceptable threshold Z_max exist). The system immediately executes the self-healing subroutine: first, it records the current defect location coordinates, and controls the three-dimensional precision electric translation stage 1 to return the combined nozzle 5 to those coordinates. Voltage is then applied again, and the main ink injection pump and the induction solvent injection pump are activated for a second, targeted, and quantitative print to repair the defect.

[0046] After repair, perform the impedance measurement again. If the impedance value returns to normal, continue with the subsequent procedures; if it is still abnormal, repeat the steps until the repair is successful.

[0047] Step 4: Spacing Adjustment: When the spacing or aspect ratio between adjacent upper and lower substrates to be printed on the piezoelectric array substrate changes, the angle of the combined nozzles, the voltage of the high-voltage DC power supply, the feed amount of printing ink and inducing solvent, and the printing speed are adjusted by using the angle-adjustable mounting base to adapt to array structures with different spacing and aspect ratios.

[0048] Example 3: In this embodiment of the printing method, the specific value of the repair amount (the total amount of main ink and inducing solvent) is related to the detected impedance anomaly degree (i.e., the magnitude of the Z-value deviation from the threshold). The deviation percentage is calculated according to (Z-Z_max) / Z_max, and the deviation percentage is used as the proportion of the repair amount to the normal printing amount to complete the fixed-point quantitative repair. If the deviation percentage is 30%, then the repair amount is 30% of the normal printing amount for fixed-point repair; if the deviation percentage is 20%, then the repair amount is 20% of the normal printing amount for fixed-point repair.

[0049] Instead of continuous flow, the repair process uses a pulse mode of the main ink precision injection pump 9 and the induction solvent precision injection pump.

[0050] Example 4: In this embodiment, when the spacing between the upper substrate 14 and the lower substrate 16 of the piezoelectric element array substrate (i.e. Figure 1 The depth (in the Z direction) was changed from 150μm to 400μm, and the distance between the front and back of the array was also changed. Figure 1 When the aspect ratio (in the Y direction) of the array is switched from 1:1 to 1:2 (height 800μm), the angle of the combined printing nozzle 5 is adjusted from 20° to 30° by the angle-adjustable mounting base and locked, the voltage is adjusted from 1100V to 1250V, and the printing speed, ink feed rate, and induction solvent feed rate are also adjusted synchronously.

[0051] Example 5: In the printing method of this embodiment, the normal printing volume of the main nozzle and the inducing solvent is set, and data on printing speed, ink feed volume, inducing solvent feed volume, and voltage of high voltage DC power supply are obtained when array structures with different spacing and aspect ratios meet the surface roughness requirements and impedance detection requirements. Establish a model relating the spacing, aspect ratio, printing speed, ink feed rate, induction solvent feed rate, and voltage; When the visual positioning control system detects changes in spacing and aspect ratio, it automatically adjusts the printing speed, ink feed rate, induction solvent feed rate, and voltage using the aforementioned relationship model.

[0052] The surface roughness of the printed electrode was measured using an AFM atomic force microscope, and the impedance value was detected using an impedance analyzer. In this embodiment, the surface roughness requirement is within 300 nm.

[0053] Any aspects not described in this embodiment are applicable to existing technologies.

Claims

1. A hydrodynamic printing device for micro-pitch sidewall electrodes, comprising a precision motion platform, a multi-functional integrated printing module, a quality inspection module, an electric field generation module, and a vision positioning control system; characterized in that: The precision motion platform is used to provide nanometer-level precision motion in the X, Y, and Z directions for the piezoelectric array substrate fixed on it to be processed. The multi-functional integrated printing module includes a rigid support arm for horizontal feeding, a combined nozzle, and an angle-adjustable mounting base for adjusting and locking the combined nozzle. The combined nozzle uses a concentric sleeve composed of an inner tube and an outer tube. The inner tube has a main ink chamber, and the annular area between the inner and outer tubes is divided into four independent chambers. The annular areas on the upper and lower sides of the main ink chamber are solvent induction chambers, and the annular areas on the left and right sides of the main ink chamber are recovery chambers. The main ink chamber is connected to an external main ink precision injection pump via a main ink delivery pipe to provide printing ink; the induction solvent chamber is connected to an external induction solvent precision injection pump via an induction solvent delivery pipe to deliver low surface tension induction solvent; and the recovery chamber is connected to an external negative pressure pump via a recovery pipe to recover printing waste liquid. The outer wall of the combined nozzle is symmetrically provided with long grooves for mounting micro probes on both the left and right sides along its length. The quality inspection module is used for in-situ detection of electrode resistance and includes a microprobe and an impedance analyzer. One end of the microprobe is slidably installed in the long groove, and the other end of the microprobe is tilted downward. The lowest point of the microprobe is lower than the lower end of the outer wall of the combined spray needle and can contact the object being tested during the detection process. The microprobe is electrically connected to the impedance analyzer. The electric field generation module includes a high-voltage DC power supply, used to form a stable electric field between the combined nozzle and the lower substrate of the piezoelectric array substrate to be processed; The vision positioning control system is used to identify the positions of the piezoelectric array substrate to be processed and to assist in the positioning of the front end of the combined nozzle.

2. The apparatus according to claim 1, characterized in that, The positive terminal of the high-voltage DC power supply is connected to the metal outer wall of the combined spray needle through a wire, continuously supplying positive charge to the combined spray needle, exciting induction to induce negative charge on the lower substrate of the piezoelectric element array substrate at the processing position, forming a self-induced electric field, thereby forming a stable induced electric field between the tip of the combined spray needle and the substrate. The angle-adjustable mounting base, quality inspection module, main ink precision injection pump, negative pressure pump, induction solvent precision injection pump, electric field generation module, and precision motion platform are all electrically connected to the vision positioning control system.

3. The apparatus according to claim 1, characterized in that, The device delivers a low surface tension inducing solvent to the printing site through the inducing solvent chambers on both sides of the combined nozzle, causing the printing ink delivered by the main ink chamber to flow from both sides to the center, pulling the particles back from the edges and dispersing them evenly. It utilizes the controlled Malagoni effect to suppress coffee rings and ensure uniform microfilm formation. At the same time, the microprobe measures the electrical impedance of the printed section online and judges the electrode quality in real time based on the measurement data. If a defect is found, a self-healing program is triggered, controlling the combined nozzle to return for a fixed-point secondary printing. In addition, residual printing waste liquid can be collected through the left and right recovery chambers before and after printing.

4. The apparatus according to claim 1, characterized in that, The precision motion platform unit includes a three-dimensional precision electric translation stage, a base, and a vacuum chuck fixture. The three-dimensional precision electric translation stage is fixed to the base by bolts and is used to provide nanometer-level precision motion in the X, Y, and Z directions. The vacuum chuck fixture is mounted on the three-dimensional precision electric translation stage and moves with the three-dimensional precision electric translation stage to adsorb and fix the piezoelectric array substrate to be processed.

5. The apparatus according to claim 1, characterized in that, The angle-adjustable mounting base has a precision scale to ensure that the combined spray needles can be accurately deflected and locked within the range of 0°-90°.

6. The apparatus according to claim 1, characterized in that, The combined nozzle includes a slender cylindrical ring and connecting components. The slender cylindrical ring is cylindrical in shape and made of a corrosion-resistant metal material with a smooth inner wall that does not chemically react with the ink. It has an annular cavity inside, and the ratio of the inner and outer ring radii of the slender cylindrical ring is 1:1.5~3. Baffles are symmetrically arranged on the left and right sides along the outer wall of the inner ring inside the annular cavity, dividing the annular cavity into two symmetrical recovery chambers on the left and right sides and two symmetrically arranged solvent induction chambers on the top and bottom. The inner area of ​​the inner ring is the main ink chamber. The connecting component is a flat cylindrical shape, and its exterior is used to connect with the angle-adjustable mounting base. The connecting component is provided with a circuit that connects the upper and lower induction solvent chambers and converges into the induction solvent delivery pipeline, and a circuit that connects the left and right recovery chambers and converges into the recovery pipeline, near the slender cylindrical ring. The outer diameter of the combined spray needle is 100~150μm, and the spacing between the upper and lower substrates of the piezoelectric array substrate to be processed is the outer diameter of the combined spray needle, and the spacing is 150μm~1mm. The rigid support arm is shaped like a "7" and includes a horizontal section and a vertical section. One end of the vertical section is fixed to the base of the precision motion platform, and the other end is connected to the horizontal section. The horizontal section is set parallel to the upper and lower substrates of the piezoelectric array substrate to be processed.

7. A hydrodynamic printing method for micro-pitch sidewall electrodes, characterized in that, The method, employing the apparatus according to any one of claims 1-6, comprises the following steps: The first step is positioning: the piezoelectric array substrate to be processed is fixed on a precision motion platform, which can adjust the three-dimensional spatial position of the piezoelectric array substrate. The precision motion platform is adjusted so that the combined nozzles are fed horizontally between the adjacent upper and lower substrates of the piezoelectric element array substrate. The distance between the upper and lower substrates is within 1mm. The printing path is planned, and then the combined nozzles are deflected to the optimal angle by the angle-adjustable mounting base to complete the printing positioning. The second step is to begin printing: Turn on the high-voltage DC power supply and apply a DC voltage of 800-1500 V; turn off the negative pressure pump and turn on the main ink precision injection pump to supply conductive ink at a rate of 1-9 μL / min. Under the action of the electric field, the ink forms a stable liquid bridge; simultaneously, control the three-dimensional precision electric translation stage of the precision motion platform to move the substrate uniformly along the X-axis at a speed of 1-9 mm / s; 0.05-0.2 s after the start of printing, turn on the induction solvent precision injection pump to release 0.5-1 μL of induction solvent; the surface tension of the induction solvent is lower than that of the main ink. The solvent spreads on the surface of the liquid bridge and promotes the smoothness of the liquid film through the Malagoni effect; After printing is complete, the negative pressure pump is turned on to recover the solution that has accumulated at the ink outlet of the combined inkjet needle through the recovery chamber, preventing dripping. The third step is detection and repair: After printing the sidewall of one array element, the platform pauses; the visual positioning control system controls the impedance analyzer to work, and uses a micro probe to measure the impedance of the newly printed electrode, obtaining the impedance value Z; the measured impedance value Z is compared with the preset qualified threshold [Z_min, Z_max]; if it is within the preset qualified threshold, the electrode quality is determined to be qualified, and the system continues to print the next array element; Z_min and Z_max are the lower and upper limits of the qualified threshold, respectively; If Z exceeds the acceptable threshold range, there are pores, cracks, or unevenness. The system immediately executes the self-healing subroutine; records the current position coordinates that exceed the acceptable threshold range, controls the three-dimensional precision electric translation stage of the precision motion platform to return the combined nozzles to the position coordinates, applies voltage again and turns on the main ink injection pump and the induction solvent injection pump to perform a fixed-point, quantitative secondary printing to repair the defects. After repair, measure the impedance again. If the impedance value returns to normal, continue with the subsequent process; if it is still abnormal, repeat the steps until the repair is successful. Step 4: Spacing Adjustment: When the spacing or aspect ratio between adjacent upper and lower substrates to be printed on the piezoelectric array substrate changes, the angle of the combined nozzles, the voltage of the high-voltage DC power supply, the feed amount of printing ink and inducing solvent, and the printing speed are adjusted by using the angle-adjustable mounting base to adapt to array structures with different spacing and aspect ratios.

8. The method according to claim 7, characterized in that, The method includes: Set the normal printing volume of the main nozzle and the inducing solvent, and obtain data on printing speed, ink feed volume, inducing solvent feed volume, and voltage of high voltage DC power supply when establishing array structures with different spacing and aspect ratios to meet surface roughness requirements and impedance detection requirements. Establish a model relating the spacing, aspect ratio, printing speed, ink feed rate, induction solvent feed rate, and voltage; When the visual positioning control system detects changes in spacing and aspect ratio, it automatically adjusts the printing speed, ink feed rate, induction solvent feed rate, and voltage using the aforementioned relationship model.

9. The method according to claim 7, characterized in that, The process of determining quantitative repair is as follows: the total amount of main ink and inducing solvent is recorded as the repair amount. The specific value of the repair amount is related to the detected impedance abnormality, i.e., the deviation of the Z value from the threshold. The deviation ratio is calculated according to (Z-Z_max) / Z_max. The deviation ratio is used as the proportion of the repair amount to the normal printing amount. Quantitative repair is completed with the determined repair amount. Continuous flow is not used during repair. Instead, the repair is performed using the pulse mode of the main ink precision injection pump and the inducing solvent precision injection pump.

10. The method according to claim 9, characterized in that, The surface roughness of the printed electrode was measured using an AFM atomic force microscope, and the impedance value was detected using an impedance analyzer.

Images