Additive manufacturing system, method for forming an additive manufacturing system, and method for forming a composite structure

Abstract

Various embodiments may provide an additive manufacturing system for forming a composite structure. The system may include a first pool containing an activating solution for forming a first printed portion of the workpiece, the activating solution including a solvent, an activating seed soluble in the solvent, and a photocurable resin. The system may also include a second pool containing an additional photocurable resin for forming a second printed portion of the workpiece, and a light source configured to provide light. The system may further include a mask configured to be positioned such that the light provided by the light source is irradiated through the mask onto the workpiece, and a third pool containing a cleaning solution or mixture for cleaning the workpiece. The first printed portion including the activating seed may be configured to form a metal layer by an electroless deposition process, thereby forming a composite structure.

Description

Cross-reference of related applications

[0001]

[0001] This application claims priority to Singapore Patent Application No. 10202103820, filed on 14 April 2021, the contents of which are incorporated herein by reference in their entirety for all purposes. [Technical Field]

[0002]

[0002] Various aspects of this disclosure relate to additive manufacturing systems. Various aspects of this disclosure relate to methods for forming additive manufacturing systems. Various aspects of this disclosure may provide methods for forming composite structures according to various embodiments. Background

[0003]

[0003] The formation of specific metal patterns on three-dimensional (3D) plastic parts has attracted considerable research interest for potential applications in 3D smart electronics, telecommunications technology, micro / nano sensors, micro-electromechanical systems (MEMS), and even quantum science. In contrast to conventional two-dimensional (2D) printed circuit boards (PCBs), 3D metal-plastic composite functional devices have more complex and elaborate structures with higher design freedom and higher integration density. Selective construction of metallization layouts in specific areas of a 3D substrate can enable the fabrication of interconnected devices with a variety of complex geometric shapes. These 3D metal-plastic structures significantly reduce size requirements compared to standard planar printed electronics, thus enabling further miniaturization of functional devices. Nevertheless, it is difficult to construct interconnected metal patterns on the surface of more complex 3D parts using conventional microfabrication techniques such as lithography, deposition, etching, and delamination. Since the fabrication of 3D metal-plastic components requires laser direct structuring (LDS), the fabrication of such parts can be expensive and may involve long manufacturing cycles, high complexity, and low design flexibility.

[0004]

[0004] The combination of computer-aided design (CAD) and 3D printing (3DP) enables the fabrication of a wide range of complex shapes through a layer-by-layer manufacturing process. Despite 3DP's greater design flexibility and superior processing capabilities, the technology has not reached its full potential in terms of forming 3D metal-plastic structures due to the limited range of materials available. To address this problem, researchers are focusing on creating conductive structures by combining 3DP with metallization techniques. Several studies have attempted to replace 3D metal-plastic structures used in fields such as electronics with a variety of conductive materials, including metal nanoparticles, graphene, multi-wall carbon nanotubes, and carbon black. These materials are often used as conductive fillers to obtain modified materials applicable to 3DP. While some types of microstructured circuits have been successfully fabricated using this method, these fillers are typically expensive, and modified materials tend to exhibit reduced print accuracy and performance after molding. Furthermore, the complex preparation processes associated with this technology tend to result in slow method development. In contrast, most studies have investigated the metallization of 3D printed parts by electroplating (EP), electroless plating (ELP), vacuum deposition (VE), and sputtering. In this way, complex 3D printed structures with metallic surfaces have been obtained. Of these methods, ELP is the most cost-effective technique for depositing metal onto non-metallic structures. ELP is based on simple wet chemical processes and allows for the deposition of a uniform metallic coating on the surface of a part without the application of an external potential. However, while many researchers have used 3DP and ELP to fabricate microstructures with specific functions, most of these parts do not meet the complex topological requirements of 3D metal-plastic parts intended to function as either non-conductive or conductive substrates. For this reason, multi-material 3DP (MM3DP) technology has been proposed as a means of achieving pattern-selective ELP. Using MM3DP, materials with specific functions can be applied to any location on the part to form interconnected 3D patterns that can be used to initiate the ELP process.Before performing ELP, activation-sensitized pretreatment is required, and this requirement has been utilized to achieve patterned plating. The simplest method for this process is to roughen specific areas on the material surface by creating a microstructure. This technique utilizes the change in capacity of the roughened surface to adsorb an activated / sensitized palladium (Pd) catalyst that induces the subsequent ELP reaction. However, while selective metallization can be achieved in this way, the resulting precision and resolution are still unsatisfactory. As a result, some researchers have proposed activating Pd based on the generation of structures with opposite charges. 2+ and Ag + We have prepared materials with electrode properties that enable more precise adsorption of seeds. In this method, the electrode region may react with ions in the treatment solution when performing ELP, but the plating accuracy is improved to some extent. In contrast to these indirect activation pathways, other methods involve Pd 2+ and Ag + Metal-plastic composite structures are fabricated by directly adding activated seeds containing ions such as [specific ions] to the material. Unfortunately, problems related to the dispersion of the activator in the material limit the application of this technique to only a few 3DP processes. Furthermore, the quality of the resulting coating is insufficient, and the adhesion of the plated metal to the substrate material is similarly inadequate. Therefore, challenges remain in achieving high precision and performance in the fabrication of metallized components with complex structures. Summary

[0005]

[0005] Various embodiments can provide an additive manufacturing system for forming a composite structure. The system may include a first pool containing or configured to contain an active solution or mixture for forming a first printed portion of a workpiece, wherein the active solution or mixture contains a solvent, an activated seed soluble in the solvent, and a photocurable resin. The system may also include a second pool containing or configured to contain a further photocurable resin for forming a second printed portion of the workpiece. The system may further include a light source configured to provide light. The system may further include a mask configured to be positioned so that light provided by the light source is irradiated onto the workpiece through the mask. The system may also include a third pool containing or configured to contain a cleaning solution or mixture for cleaning the workpiece. The first printed portion containing the activated seed may be configured to form a metal layer by an electroless deposition process, thereby forming a composite structure.

[0006]

[0006] Various embodiments can provide a method for forming an additive manufacturing system for forming a composite structure. The method may include providing a first pool containing or configured to contain an active solution or mixture for forming a first printed portion of a workpiece, wherein the active solution or mixture contains a solvent, an activated seed soluble in the solvent, and a photocurable resin. The method may also include providing a second pool containing or configured to contain a further photocurable resin for forming a second printed portion of a workpiece. The method may further include providing a light source configured to provide light. The method may further include providing or positioning a mask such that light provided by the light source irradiates the workpiece through the mask. The method may also include providing a third pool containing or configured to contain a cleaning solution or mixture for cleaning the workpiece. The first printed portion containing the activated seed is configured to form a metal layer by an electroless deposition process, thereby forming a composite structure.

[0007]

[0007] Various embodiments can provide a method for forming a composite structure. The method may include depositing an activated solution or mixture comprising a solvent, an activated seed soluble in the solvent, and a photocurable resin to form a first printed portion of a workpiece. The method may also include depositing a further photocurable resin to form a second printed portion of the workpiece. The method may further include irradiating the workpiece with light provided by a light source through a mask. The method may also include dispensing a cleaning solution or mixture for cleaning the workpiece. The method may further include forming a metal layer on the first printed portion by an electroless plating process due to the activated seed contained in the first printed portion, thereby forming a composite structure.

[0008]

[0008] The present invention will be better understood by referring to the detailed description, in conjunction with non-limiting examples and the accompanying drawings. [Brief explanation of the drawing]

[0009] [Figure 1] This diagram shows an overall view of an additive manufacturing system with various embodiments for forming a composite structure. [Figure 2] This shows an overall diagram of a method for forming an additive manufacturing system for creating a composite structure. [Figure 3] This shows an overall diagram of a method for forming a composite structure according to various embodiments. [Figure 4] This is a schematic diagram illustrating the multi-material digital photoprocessing 3D printing (MM-DLP3DP) process in various embodiments. [Figure 5] (a) Multi-material digital optical processing 3D printing (MM-DLP3DP) apparatus according to various embodiments, and (b) Numerical processing of a multi-material model in which slicing data is obtained by processing different material topologies within the same part as separate slicing units according to various embodiments. [Figure 6]This is a schematic diagram illustrating various embodiments of printing arbitrary complex multi-material models and printing processes for printing such models. [Figure 7] (a) Plots of absorption as a function of wavelength (in nanometers or nm) showing the ultraviolet spectra of rigid photocurable resins before and after modification with palladium (Pd2+) ions according to various embodiments, and (b) Plots of absorption as a function of wavelength (in nanometers or nm) showing the ultraviolet spectra of flexible photocurable resins before and after modification with palladium (Pd2+) ions according to various embodiments. [Figure 8] (a) Three microstructured metallized surfaces, each with a thickness of 200 μm, using processes according to various embodiments: a circle with a radius of 200 μm, a regular hexagon with an inner radius of 200 μm, and a circular groove with a groove width of 400 μm; (b) A skeletal ball structure having a circular base covered with Ni metal using processes according to various embodiments; (c) An Eiffel Tower having a microstructure in which selected parts are uniformly covered with nickel (Ni) plating using processes according to various embodiments; (d) A five-faced structure having a complex nickel (Ni) metal distribution and having multi-material nests between and within layers using processes according to various embodiments; (e) A dome structure having an arc-shaped metal distribution using processes according to various embodiments; (f) Construction and metallization of small structures within resin. (i) U-shaped tubes with an internal metal mesh 1 mm thick, each having a regular hexagon with an inner diameter of 500 μm, using processes according to various embodiments; (g) double-layer 3D hollow nested components, i.e., a large sphere (radius 15 mm) having a triangular hollow hole enclosing a small sphere (radius 8 mm) having a regular hexagonal hollow hole, with nickel (Ni) selectively deposited using processes according to various embodiments; (h) flexible carbon nanotube structures with selective three-dimensional (3D) metallization using processes according to various embodiments, showing no fracture after deformation; and (i) wearable structures with nickel (Ni) plating formed by processes according to various embodiments, having a complex shape and remaining firmly bonded to a flexible substrate after deformation. [Figure 9](a) A light-emitting diode (LED) stereo circuit having a complex nickel (Ni) metal wire topology using processes according to various embodiments; (b) A double-layer three-dimensional (3D) circuit structure having a complex three-dimensional (3D) copper wire structure using processes according to various embodiments, which is difficult to fabricate using conventional processes; and (c) A plot of impedance (in ohms or Ω) as a function of frequency (in Hertz or Hz) showing the impedance of nickel (Ni) and copper (Cu) coatings formed using processes according to various embodiments. [Figure 10] (a) Nickel (Ni) plated structures with widths of 1 mm, 500 μm, and 100 μm, as well as 50 μm and 40 μm, formed by processes according to various embodiments, and (b) circuit board components with a width of 1 mm incorporating 500 μm copper wires, formed by processes according to various embodiments. Figure 10(a) shows images of Ni wires with widths of 1 mm, 500 μm, 100 μm, 50 μm, and 40 μm. High-magnification microscopy shows that Ni is precisely distributed on these active precursor wires, thus demonstrating the exceptional resolution and effectiveness of the printing method in selective metal deposition. The Cu plating on the circuit board shown in Figure 10(b) demonstrates that various embodiments can provide a manufacturing resolution of at least 40 μm, sufficient to meet the processing requirements of most electronic products. [Figure 11](a) Standard flat nickel (Ni) plating according to various embodiments, (b), (c) Scanning electron microscope (SEM) images of the area shown in (a) at different magnifications according to various embodiments, (d) Nickel (Ni) plating on the surface of a circular microstructure according to various embodiments, (e), (f) Scanning electron microscope (SEM) images of the area shown in (d) at different magnifications according to various embodiments, (g) Nickel (Ni) plating on the surface of annular groove microstructure according to various embodiments, (h), (i) Scanning electron microscope (SEM) images of the area shown in (g) at different magnifications according to various embodiments, (j) Nickel (Ni) plating on the surface of a regular hexagonal microstructure according to various embodiments, (k) to (l) Scanning electron microscope (SEM) images of the area shown in (j) at different magnifications according to various embodiments, (m) Flexible sample with nickel (Ni) plating, and (n) to (o) Scanning electron microscope (SEM) images of the area shown in (m) at different magnifications according to various embodiments. [Figure 12] (a) Cross-sectional transmission electron microscope (TEM) images showing the resin layer, bonding layer, and nickel layer of the composite structure according to various embodiments; (b) Energy-dispersive X-ray spectroscopy (EDS) images showing the distribution of iron according to various embodiments; (c) Energy-dispersive X-ray spectroscopy (EDS) images showing the distribution of palladium according to various embodiments; and (d) Energy-dispersive X-ray spectroscopy (EDS) images showing the distribution of nickel according to various embodiments. [Figure 13](a) schematic diagrams of three-dimensional (3D) printed integrated strain gauges on a measured object according to various embodiments; (b) images of strain gauges according to various embodiments and schematic diagrams relating to the measurement of strain gauges according to various embodiments; (c) images showing the bending deformation of the gauge under stress according to various embodiments; (d) plots of voltage (in volts or V) as a function of load (in grams or g) showing the voltage measurement characteristics of strain gauges according to various embodiments; (e) plots of strain as a function of load (in grams or g) showing the strain characteristics of strain gauges according to various embodiments calculated from experimental data; and (f) plots of deformation (in millimeters or mm) as a function of load (in grams or g) showing experimental deformation data of strain gauges according to various embodiments. [Figure 14] (a) schematic diagrams showing the operating principles of three-dimensional (3D) printed piezoelectric sensors according to various embodiments; (b) images showing piezoelectric sensors according to various embodiments bent at bending angles of 30°, 60°, 90° and 120°; (c) plots of voltage (in volts or V) as a function of time (in seconds or s) showing the voltage waveforms generated by piezoelectric sensors according to various embodiments at 30°, 60°, 90° and 120°; and (d) plots of voltage (in volts or V) as a function of deformation (in nanometers or nm) showing the voltage generated by piezoelectric sensors in a tensile state according to various embodiments as a function of deformation. [Figure 15] (a) A schematic diagram showing a measurement system including three-dimensional (3D) electrocardiogram (ECG) electrodes formed according to various embodiments; (b) Images showing the device components of the system including electrodes formed according to various embodiments; (c) A plot showing five electrocardiogram (ECG) signals measured by electrodes formed according to various embodiments based on random measurements of a stationary subject; and (d) A plot showing electrocardiogram (ECG) signals measured by electrodes formed according to various embodiments based on measurements taken when the subject is swinging its arm, clicking a computer mouse, and writing. Detailed explanation

[0010]

[0009] The following detailed description refers to the accompanying drawings that illustrate specific details and embodiments in which the present invention may be implemented. These embodiments are described in sufficient detail to enable those skilled in the art to implement the present invention. Without departing from the scope of the present invention, other embodiments may be utilized and structural and logical changes may be made. Since some embodiments can form new embodiments in combination with one or more other embodiments, the various embodiments are not necessarily mutually exclusive.

[0011]

[0010] Embodiments described in the context of one of the present methods or additive manufacturing systems are equally applicable to other methods or additive manufacturing systems. Similarly, embodiments described in the context of a method are equally applicable to a system, and vice versa.

[0012]

[0011] Features described in the context of one embodiment may be applicable correspondingly to the same or similar features of other embodiments. Features described in the context of one embodiment may be applicable correspondingly to other embodiments even if not explicitly described in these other embodiments. Furthermore, the additional and / or combined and / or alternative descriptions of features in the context of one embodiment may be applicable correspondingly to the same or similar features of other embodiments.

[0013]

[0012] In the context of various embodiments, the articles "a," "an," and "the" used with respect to a feature or element include reference to one or more features or elements.

[0014]

[0013] In the context of various embodiments, the terms "about" or "approximately" applied to a numerical value include the exact value and a reasonable variance.

[0015] 【0照014】As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0016]

[0015] Various embodiments may relate to a simple means of fabricating metal-plastic functional devices having complex shapes based on a multi-material digital photoprocessing 3DP (MM-DLP3DP) process. This technique can enable the fabrication of microstructures comprising an active precursor and substrate material having a specific 3D spatial distribution that can selectively activate ELP. The active precursor is Pd 2+ It can be prepared by adding a saturated aqueous solution of ions to a water-washable photocurable resin (either rigid or flexible). Subsequently, complex microstructures with a specific topological distribution of material properties (including combinations of standard resin and active precursor) can be fabricated using an MM-DLP3DP apparatus equipped with multiple workstations. After a simple washing process, the material was directly plated and metallized using an ELP with a 3D pattern. Pd 2+ The ions could be uniformly dispersed throughout the active precursor, and by irradiating the treated resin with patterned UV light, the photoinitiator generated free radicals. These radicals were then combined with the monomer and Pd 2+ Double bond crosslinking reactions can be initiated between low molecular weight polymers and ions to produce rigid, hardened structures. In the plating bath, Pd exposed on the surface of the material 2+ The ions can be reduced to Pd by NaH2PO2, forming Pd particles that can then function as catalytic nuclei, which subsequently induce the deposition of the target metal. This method can produce bonding layers in which the deposited metal is microscopically embedded in a plastic layer. This technique can simplify the manufacturing process and reduce costs while providing the ability to produce a variety of complex 3D structures with specific metal patterns.

[0017]

[0016] Figure 1 shows an overall diagram of an additive manufacturing system according to various embodiments for forming a composite structure. The system may include a first pool 102 containing or configured to contain an active solution or mixture for forming a first printed portion of a workpiece, the active solution or mixture comprising a solvent, an activated seed soluble in the solvent, and a photocurable resin. The system may also include a second pool 104 containing or configured to contain a further photocurable resin for forming a second printed portion of the workpiece. The system may further include a light source 106 configured to provide light. The system may further include a mask 108 configured to be positioned so that light provided by the light source 106 is irradiated onto the workpiece through the mask. The system may also include a third pool 110 containing or configured to contain a cleaning solution or mixture for cleaning the workpiece. The first printed portion containing the activated seed may be configured to form a metallic layer by an electroless deposition process, thereby forming a composite structure.

[0018]

[0017] In other words, the additive manufacturing system may include a first pool 102, a second pool 104, and a third pool 110 for storing the active solution or mixture, further photocurable resin, and cleaning solution or mixture, respectively. The additive manufacturing system may also include a light source 106 and a mask 108.

[0019]

[0018] To avoid misunderstanding, Figure 1 is intended to illustrate additive manufacturing systems with specific features according to various embodiments, and is not intended to limit the arrangement, size, shape, orientation, etc., of the features.

[0020]

[0019] In various embodiments, the activation seed may be a catalyst or a catalyst precursor. The catalyst precursor may contain metal ions such as palladium ions or silver ions. The catalyst may contain metals such as palladium metal or silver metal.

[0021]

[0020] In various embodiments, the photocurable resin and the further photocurable resin may be made of the same material. In various other embodiments, the photocurable resin and the further photocurable resin may be made of different materials.

[0022]

[0021] Generally speaking, the light can be any light capable of curing the photocurable resin and further photocurable resins. The light source 106 may be selected based on the ability of the light emitted by the light source 106 to cure the resin. In various embodiments, the light can be ultraviolet light or visible light. However, in various other embodiments, the light may be any other light capable of curing the photocurable resin and further photocurable resins.

[0023]

[0022] The mask 108 can be any suitable mask. The mask 108 may be configured to allow light to pass through and illuminate specific parts of the first and / or second printed areas, while blocking light from illuminating other areas, thereby forming a masking pattern. For example, the mask 108 may be a liquid crystal display (LCD) mask.

[0024]

[0023] In various embodiments, the additive manufacturing system may also include a controller electrically connected to the first pool 102, the second pool 104, the third pool 110, the light source 106, and the mask 108.

[0025]

[0024] Various embodiments may relate to printing using a multi-material nesting topology. In various embodiments, the controller may be configured to control a first pool 102 to deposit an active solution or mixture at a predetermined location on the substrate or underlayer to form a first printed portion. The controller may be configured to control a mask 108 to generate a first masking pattern, or to position or position a mask 108 having the first masking pattern. The controller may be further configured to control a light source 106 to irradiate the first printed portion with light through the first masking pattern, thereby curing at least one slice of the first printed portion. The controller may be further configured to control a third pool 110 to distribute a cleaning solution or mixture for cleaning the first printed portion and to remove any remaining uncured slices of the first printed portion. The controller may also be configured to control a second pool 104 to deposit an additional photocurable resin at another predetermined location on the substrate or underlayer to form a second printed portion. The controller may also be configured to control the mask 108 to generate a second masking pattern, or to position or position a further mask having the second masking pattern. The controller may also be configured to control the light source 106 to irradiate the second printed portion with light through the second masking pattern, thereby curing at least one slice of the second printed portion. The controller may further be configured to control the third pool 110 to distribute a cleaning solution or mixture for cleaning the second printed portion and to remove any remaining uncured slices of the second printed portion.

[0026]

[0025] Various embodiments may relate to printing using an interlayer multi-material lamination topology. In various embodiments, the controller may be configured to control a first pool 102 to deposit an active solution or mixture onto a substrate or underlayer to form a first printed portion. The controller may be configured to control a mask 108 to generate a first masking pattern, or to position or position a mask having the first masking pattern. The controller may be further configured to control a light source 106 to irradiate the first printed portion with light through the first masking pattern, thereby curing at least one slice of the first printed portion, the cured slice of the first printed portion forming a first layer. The controller may be further configured to control a third pool 110 to distribute a cleaning solution or mixture for cleaning the first printed portion and to remove any remaining uncured slices of the first printed portion. The controller may also be configured to control a second pool 104 to deposit additional photocurable resin on the cured slice of the first printed portion to form a second printed portion. The controller may also be configured to control the mask 108 to generate a second masking pattern, or to position or position a further mask having the second masking pattern. The controller may further be configured to control the light source 106 to irradiate the second printing portion through the second masking pattern with light, thereby curing at least one slice of the second printing portion, the cured slice of the second printing portion forming a second layer on top of the first layer. The controller may also be further configured to control the third pool 110 to distribute a cleaning solution or mixture for cleaning the first and second printing portions, removing any remaining uncured slices of the second printing portion.

[0027]

[0026] In various embodiments, the additive manufacturing system may also include one or more additional pools containing a cleaning solution or mixture for cleaning the workpiece. The cleaning solution or mixture may be a liquid containing water, alcohol and / or acid. The cleaning solution or mixture may include, for example, ethanol, acetone and sulfuric acid. The cleaning solution or mixture may be configured to clean the substrate and / or the printed portion. Furthermore, the cleaning solution or mixture may be further configured to remove uncured resin. In various embodiments, the first pool 102, the second pool 104, the third pool 110, and one or more additional pools may each be containers or tanks.

[0028]

[0027] In various embodiments, the additive manufacturing system may include a printer comprising a first pool 102, a second pool 104, and a third pool 110. The printer may also include one or more additional pools containing or configured to contain a cleaning solution or mixture. The printer may also include a light source 106, a mask 108, and / or a controller. The printer may also be referred to as a multi-material digital photoprocessing three-dimensional printing (MM-DLP3DP) device.

[0029]

[0028] In various embodiments, the additive manufacturing system may include a plating bath for forming a metal layer by an electroless plating process. The plating bath may be a standalone component or may be included in the printer's fourth pool. In other words, the plating bath may be integrated with the printer or may be separate from the 3D printer.

[0030]

[0029] In various embodiments, the metal layer may include a metal or a metal alloy. For example, the metal layer may include an alloy containing nickel metal, copper metal, gold metal, cobalt metal, silver metal, platinum metal, or any combination thereof.

[0031]

[0030] In various embodiments, the metal layer may be formed on or covering the first printed portion. In various embodiments, a bonding layer may be formed between the metal layer and the first printed portion. The bonding layer may be formed by interaction or diffusion between the metal or metal alloy of the metal layer and the active solution or mixture contained in the material contained in the first printed portion. In various embodiments, the composite structure may be a strain gauge, a piezoelectric sensor, or an electrocardiogram (ECG) electrode.

[0032]

[0031] Figure 2 shows an overall diagram of a method for forming an additive manufacturing system for forming a composite structure. The method may include, in 202, providing a first pool containing or configured to contain an active solution or mixture for forming a first printed portion of a workpiece, the active solution or mixture comprising a solvent, an activated seed soluble in the solvent, and a photocurable resin. The method may also include, in 204, providing a second pool containing or configured to contain a further photocurable resin for forming a second printed portion of a workpiece. The method may further include, in 206, providing a light source configured to provide light. The method may further include, in 208, providing or positioning a mask such that light provided by the light source irradiates the workpiece through the mask. The method may also include, in 210, providing a third pool containing or configured to contain a cleaning solution or mixture for cleaning the workpiece. The first printed portion containing the activated seed is configured to form a metal layer by an electroless deposition process, thereby forming a composite structure.

[0033]

[0032] In other words, the method may include providing a first pool, a second pool, and a third pool, as well as a mask and a light source.

[0034]

[0033] To avoid misunderstanding, Figure 2 is not intended to limit the order of the various steps. For example, step 202 can be performed before, during, or after step 204.

[0035]

[0034] In various embodiments, the method may include providing or forming a controller electrically connected to the first pool, second pool, third pool, light source, and mask. The method may include electrically connecting the controller to the first pool, second pool, third pool, light source, and mask.

[0036]

[0035] In various embodiments, the method may also include providing one or more additional pools containing a cleaning solution or mixture for cleaning a workpiece.

[0037]

[0036] The first pool, the second pool, and the third pool may be part of the printer. The printer may also include a light source, a mask, and / or a controller. The printer may also include one or more additional pools containing a cleaning solution or mixture.

[0038]

[0037] In various embodiments, the method may further include providing a plating bath for forming a metal layer by an electroless plating process. The plating bath may be a standalone component or may be included in a fourth pool of the printer. In other words, the plating bath may be integrated with the printer or may be separate from the printer.

[0039]

[0038] Figure 3 shows an overall diagram of a method for forming a composite structure according to various embodiments. The method may include, in 302, depositing an active solution or mixture to form a first printed portion of a workpiece, the active solution comprising a solvent, an activated seed soluble in the solvent, and a photocurable resin. The method may also include, in 304, depositing a further photocurable resin to form a second printed portion of the workpiece. The method may further include, in 306, irradiating the workpiece through a mask with light provided by a light source. The method may also include, in 308, distributing a cleaning solution or mixture for cleaning the workpiece. The method may further include, in 310, forming a metal layer on the first printed portion by an electroless plating process due to the activated seed contained in the first printed portion, thereby forming a composite structure.

[0040]

[0039] To avoid misunderstanding, Figure 3 is not intended to limit the order of the various steps. For example, step 302 can be performed before, during, or after step 304.

[0041]

[0040] In various embodiments, the activated seed may be a catalyst or a catalyst precursor.

[0042]

[0041] In various embodiments, the photocurable resin and the further photocurable resin may be made of the same material. In various other embodiments, the photocurable resin and the further photocurable resin may be made of different materials.

[0043]

[0042] In various embodiments, the light may be any light capable of curing the photocurable resin and further photocurable resins, such as ultraviolet light or visible light.

[0044]

[0043] In various embodiments, the mask can be any suitable mask, such as a liquid crystal display (LCD) mask.

[0045]

[0044] Various embodiments may relate to printing using a multi-material nesting topology. In various embodiments, an active solution or mixture may be deposited in a predetermined location on a substrate or underlayer to form a first printed portion. The method may include generating a first masking pattern using a mask, or positioning or arranging a mask having the first masking pattern. Light may be shone on the first printed portion through the first masking pattern, thereby curing at least one slice of the first printed portion. A cleaning solution or mixture may be dispensed to clean the first printed portion and remove any remaining uncured slices of the first printed portion. Further photocurable resin may be deposited in another predetermined location on the substrate or underlayer to form a second printed portion. The method may include generating a second masking pattern using a mask, or positioning or arranging a further mask having the second masking pattern. Light may be shone on the second printed portion through the second masking pattern, thereby curing at least one slice of the second printed portion. A cleaning solution or mixture may be dispensed to clean the second printed area and remove any remaining uncured slices from the second printed area.

[0046]

[0045] Various embodiments may relate to printing using an interlayer multi-material lamination topology. In various embodiments, an active solution or mixture may be deposited on a substrate or underlayer to form a first printed portion. The method may include generating a first masking pattern using a mask, or positioning or arranging a mask having the first masking pattern. Light is shone on the first printed portion through the first masking pattern, thereby curing at least one slice of the first printed portion, the cured slice of the first printed portion forming a first layer. A cleaning solution or mixture may be dispensed to clean the first printed portion and remove any remaining uncured slices of the first printed portion. Further photocurable resin may be deposited on the cured slice of the first printed portion to form a second printed portion. The method may also include generating a second masking pattern using a mask, or positioning or arranging further masks having the second masking pattern. Light is shone onto the second printing area through the second masking pattern, thereby curing at least one slice of the second printing area, and the cured slice of the second printing area forms the second layer on top of the first layer. A cleaning solution or mixture may be dispensed to clean the first and second printing areas and to remove any remaining uncured slices of the second printing area.

[0047]

[0046] In various embodiments, the cleaning solution or mixture may include water, alcohol, and acid.

[0048]

[0047] In various embodiments, the electroless plating process can be carried out by immersing the workpiece in a plating bath.

[0049]

[0048] In various embodiments, the metal layer may include a metal or a metal alloy.

[0050]

[0049] In various embodiments, the metal layer may be formed on or cover the first printed portion. In various embodiments, a bonding layer may be formed between the metal layer and the first printed portion. The bonding layer may be formed by the interaction or diffusion between the metal or metal alloy of the metal layer and the active solution or mixture contained in the material included in the first printed portion.

[0051]

[0050] Preparation of the active precursor

[0052]

[0051] As described above, the technology described herein can enable the indirect fabrication of metal-plastic composite structures by the selective three-dimensional (3D) deposition of active precursors that subsequently promote an electroless plating (ELP) reaction. By adding an activation seed to a standard photocurable resin, a precursor exhibiting high catalytic activity and positive stability was obtained.

[0053]

[0052] The photocurable resin can usually be modified by incorporating nanofluids having specific desired properties as fillers together with a dispersant that ensures a uniform distribution of these fillers. However, it has been found that the modified resin prepared in this way has low stability because the fillers tend to settle finally and the material becomes non-uniform. Furthermore, the dispersants required for different fillers can be incompatible and can degrade the physical properties of the original substrate material. To mitigate these problems, various embodiments can utilize the ability of certain water-washable photocurable resins to form a homogeneous mixture with an aqueous solution at a low concentration (less than 10%). By directly adding an aqueous solution containing an activation seed to the resin, a stable active precursor that is well mixed after sufficient stirring can be obtained.

[0054]

[0053] Palladium (Pd 2+ ) ions can bring excellent catalytic activity during ELP and are often used as activation seeds. Various embodiments described herein use an activation solution containing PdCl2 powder and NH4Cl to obtain Pd - in an aqueous solution containing chloride (Cl 2+The activation is based on the solubility of metal ions such as ions. The activation precursor can be obtained by uniformly mixing the activation solution with various resins. This method can be simple and versatile and may be applicable to most resins in which polyurethane is the main component.

[0055]

[0054] Crystalline NH4Cl was purchased from Fujifilm Wako Pure Chemical Corporation, PdCl2 nanopowder (99.0% purity) was obtained from Kanto Chemical Co., Ltd., and White rigid (washable, 405nm, ASIN: JP206000BK510), green transparent rigid (405nm, ASIN: B07CQF6QNM), acrylic (405nm, model: PMMA-like, ASIN: B07SKCNMZX), dark gray flexible (405nm, model: SK01F, ASIN: B08T929XVW) and light gray flexible light-cured resins (405nm, model: SK02F, ASIN: B08T929RXB) were supplied by Nova Robot Technology Co., Ltd., Elegoo Co., Ltd., eSun Co., Ltd., and Siraya Tech. The resins were purchased from Co., Ltd. and the SK Honpo Japan division, respectively. These resins were designated as resins #1 to #5. Each active precursor was prepared at room temperature (20°C) by dissolving 3.7 g of NH4Cl in 10 ml of deionized water, and 50 mg of PdCl2 was added and dissolved while stirring. This yielded 10 ml of saturated activated solution. This solution was left to stand for a while, and then 5 ml of the clear upper portion of the solution was removed. Subsequently, 45 ml of one of the photocurable resins was transferred to a container equipped with a magnetic stirrer rotating at 1000 rpm, and 5 ml of the activated solution was added dropwise. After this addition, the mixture was stirred for a further 30 minutes at 1200 rpm to obtain 50 ml of activated precursor solution.

[0056]

[0055] Fabrication of multi-material nested complex structures using MM-DLP3DP

[0057]

[0056] Compared to direct writing 3DP (DW3DP) and fused deposition modeling 3DP (FDM3DP), DLP3DP can enable surface molding with higher resolution, and as a result, parts with smoother surfaces, higher molding accuracy and infill rate can be obtained.

[0058]

[0057] Figure 4 is a schematic diagram showing a multi-material digital photoprocessing 3D printing (MM-DLP3DP) process according to various embodiments. In this process, a 3DP of an active solution containing a standard resin (which functions as a substrate) and an active precursor can form a part having a desired 3D topology.

[0059]

[0058] After washing and drying, the surface where the active precursor is exposed may exhibit catalytic activity. During the subsequent ELP process, catalytic ions (e.g., Pd) in the active precursor are released. 2+ The presence of ions can promote the deposition of metal particles from the solution, leading to selective deposition and the formation of a desired metallic pattern.

[0060]

[0059] Figure 5 shows (a) a multi-material digital optical processing 3D printing (MM-DLP3DP) apparatus according to various embodiments, and (b) numerical processing of a multi-material model in which slicing data is obtained by processing different material topologies within the same part as separate slicing units according to various embodiments.

[0061]

[0060] To enable the manufacture of multi-material 3D printed parts containing both standard resin and active precursor, an MM-DLP3DP device incorporating three stations or pools can be developed, as shown in Figure 5(a). The device may include a printer platform. The printing platform can be selected from three pools (called material pool A, material pool B, and wash pool), and the printing platform can move in both the x and y directions to switch between different pools to form the workpiece. By immersion in different pools, the initial layers of the workpiece may be formed by bonding to the printing platform or by suspending from the printing platform. Material pools A, B, and wash pool each hold a standard photocurable resin, an active precursor, and a wash solution or mixture. Partially formed workpieces may be held by the printing platform using adhesion or suspended, and the remaining layers of the workpiece may be formed by sequentially switching and immersing in various pools.

[0062]

[0061] The right-hand diagram of Figure 5(a) summarizes the structural features of the printer. To ensure sufficient molding accuracy and resolution, a 2K monochrome liquid crystal display (LCD) mask can be used to provide transparent graphics masking. 405 nm ultraviolet (UV) light is passed through the mask to form a light field related to a specific slice pattern, thereby enabling layered curing and molding of the part. The LCD mask may be able to move together in the x and y directions along the z-axis of the printer.

[0063]

[0062] The entire 3D printed workpiece can be moved as a single piece, thus enabling material switching and ensuring that different material topologies within the same part have precise interrelationships. Currently, obtaining digital model data of a multi-material part can be an important first step, despite the lack of mature multi-material slicing software programs that enable labeling of material properties in relation to specific complex topologies. In various embodiments, this problem can be addressed by assisting the numerical processing of the multi-material model (Figure 5(b)) using the model-assemble-deconstruct-slicing method. In this process, topologies having the same physical properties can be created as a single unit and then converted to a standard template library (STL) format. Slicing software can assemble units having different properties according to the desired topological relationships, and then slice these parts separately to obtain slice data for each. If the different parts have positional relationships defined in the part coordinate system, the slice data of different materials can incorporate the required topological relationships. Various embodiments can use control software specifically developed for slice data processing, setting printing parameters, and controlling the MM-DLP3DP system. The fabrication of multi-material parts with 3D active precursors can be achieved by performing a series of cycles in which material A is applied, followed by cleaning, and then material B is applied.

[0064]

[0063] Figure 6 is a schematic diagram showing various embodiments of an arbitrary complex multi-material model and a printing process for printing the model. As shown in Figure 6, each multi-material component having an arbitrarily complex structure can be analyzed with respect to a different material topology, regardless of its structural properties. This analysis can include both interlayer multi-material lamination topology and multi-material nesting topology. In the former case, various materials can be nested between layers, thus eliminating the need for the printer to perform cleaning and material switching processes for each slice. However, when dealing with the latter topology, the printer had to cycle through the processes of printing material A, printing material B, and cleaning each slice. Since all materials used in a component have the topological properties described above, various embodiments can enable the fabrication of various complex components, but it should be noted that the fabrication of certain components requires the support of a supporting structure. A multi-material model of any complex structure can be divided into interlayer multi-material lamination topology and multi-material nesting topology according to the desired distribution of material topology.

[0065]

[0064] Selective 3D metallization using ELP

[0066]

[0065] During processing, the printed parts may adhere firmly to the printing platform, and because the platform is made of metal, a small amount of metal residue may remain on the base of the parts after removal. This residue promotes the deposition of nickel (Ni), which may reduce the accuracy of subsequent selective ELP and interfere with the metal distribution pattern. Furthermore, uncured resin remaining on the surface of the parts may cause Pd to accumulate inside the resin. 2+This can potentially mask ions, thus affecting the catalytic activity of the active precursor during plating. For these reasons, cleaning the parts after 3DP has been essential. In various embodiments, the cleaning solution may consist of 40% ethanol (analytical purity) by volume, 50% acetone (analytical purity), and 10% dilute sulfuric acid (40% by weight). The alcohol and acetone in this mixture can dissolve the uncured resin on the surface of the part (both the standard resin substrate and the active precursor), while the sulfuric acid can remove any residual metal powder adhering to the bottom of the part.

[0067]

[0066] Unlike the ELP process used in other studies, various embodiments may not require roughening or sensitizing of the cleaned finished parts. As a result, the cleaned and dried parts can be directly immersed in the plating bath.

[0068]

[0067] The Ni plating bath used in this process may have the main components summarized in Table 1. [Table 1]

[0069]

[0068] The plating bath may have a pH of 9 and may be maintained at 70°C. In each printed multimaterial part, the active precursor (Pd 2+ The ions (which are uniformly dispersed) may be distributed on the resin substrate in a specific 3D topology. When the component is immersed in the bath, the exposed Pd on the surface 2+ The ions are first reduced to Pd monomers, which act as catalytically active metal nuclei, initiating the ELP reaction in a specific microscopic region, and thus enabling the achievement of the target Ni metal deposition.

[0070]

[0069] The reaction can be explained by the following equations (1) to (4).

number

number

number

number

[0071]

[0070] The reactions shown in formulas (1) to (4) may include a mechanism in which a reactive precursor catalyzes the directed deposition of Ni metal. In this process, hypophosphate may be oxidized in solution to produce hydrogen atoms adsorbed on the substrate surface. Immediately afterward, these hydrogen atoms may reduce Ni ions in the solution. Once the hydrogen atoms are adsorbed on the substrate surface, the reduced Ni may spontaneously deposit on the same surface after 5 to 10 minutes to form a coating. Furthermore, Pd 2+ Because the ions are embedded in the surface of the active precursor portion of the component, there is a possibility of plating layer overflow or uneven deposition due to catalyst migration during the ELP process. Since time-consuming pretreatment of the component surface is not required, the original surface morphology can be maintained, and therefore a more accurate plating pattern can be obtained.

[0072]

[0071] Characteristics of reactive precursors combined with commercially available photocurable resins

[0073]

[0072] After modification, resin #1 changed from its original white color to pale yellow. This uniform distribution of coloration is due to Pd 2+ This demonstrated that the ions were uniformly dispersed throughout the material. Similarly, the #5 resin changed from gray to yellowish-gray. After 3 days of standing, none of the materials showed any precipitation, indicating the high stability of these precursors.

[0074]

[0073] Figure 7 shows (a) palladium (Pd 2+ (b) Plots of absorption as a function of wavelength (in nanometers or nm), showing the ultraviolet spectra of the rigid photocurable resin before and after modification with ions, and (b) Palladium (Pd2+ The ultraviolet spectra of the flexible photocurable resin before and after ion modification are shown, with a plot of absorption as a function of wavelength (in nanometers or nm).

[0075]

[0074] Figure 7(a) shows the UV absorption spectra obtained from resin #1 before and after modification. Both spectra are essentially identical, with a peak absorbance at approximately 405 nm. These results indicate that Pd 2+ It can be demonstrated that the addition of the solution does not alter the basic properties of the resin, particularly its molding properties, and does not reduce the photosensitivity of the original resin. Similar results were obtained from the analysis of #4 resin before and after modification, as shown in Figure 7(b).

[0076]

[0075] Complex 3D metal-plastic composite structure

[0077]

[0076] Conventionally, circuit boards are made from flat modules or combinations of multiple flat modules, such that the processing surface is a 2D plane or a combination of such planes. Because these structures are relatively simple, the manufacturing process is not complex, but their applications are limited. The demand for more structurally complex parts with regularly cylindrical or free-form processing surfaces requires improved manufacturing capabilities. To illustrate the manufacturing capabilities of our novel method, we fabricated a metal-plastic composite part with a representative structure and then processed it with ELP. Compared with multi-material 3DP using multiple nozzles, the technique described herein can provide higher resolution and therefore can enable the construction of microstructured surfaces with special functions. This may be important because metallized microstructured surfaces have a number of potential applications.

[0078]

[0077] Figure 8 shows (a) three microstructured metallized surfaces, each with a thickness of 200 μm, using processes according to various embodiments, namely a circle with a radius of 200 μm, a regular hexagon with an inner radius of 200 μm, and a circular groove with a groove width of 400 μm, (b) a skeletal ball structure having a circular base covered with Ni metal using processes according to various embodiments, (c) an Eiffel Tower having a microstructure in which selected parts are uniformly covered with nickel (Ni) plating using processes according to various embodiments, (d) a five-faced structure having a complex nickel (Ni) metal distribution and having multi-material nests between and within layers using processes according to various embodiments, (e) a dome structure having an arc-shaped metal distribution using processes according to various embodiments, and (f) construction of small structures within resin and (g) U-shaped tubes with an internal metal mesh 1 mm thick, each having a regular hexagon with an inner diameter of 500 μm, using processes according to various embodiments to demonstrate metallization; (h) double-layered 3D hollow nested components, i.e., a large sphere (radius 15 mm) with a triangular hollow hole enclosing a small sphere (radius 8 mm) with a regular hexagonal hollow hole, with nickel (Ni) selectively deposited using processes according to various embodiments; (h) flexible carbon nanotube structures with selective three-dimensional (3D) metallization using processes according to various embodiments, demonstrating no fracture after deformation; and (i) wearable structures with nickel (Ni) plating formed by processes according to various embodiments, having a complex shape and remaining firmly bonded to a flexible substrate after deformation. Fine-sized hollow or complex heterogeneous structures, such as those shown in Figure 8, may be as small as approximately 400 μm, and precision manufacturing possible using this method has been confirmed.

[0079]

[0078] Figure 8(a) shows three different surface structures constructed on a circular substrate. These include a circular microstructure with a radius of 200 μm, a regular hexagonal microstructure with an inner circle radius of 200 μm, and a circumferential groove microstructure with a groove width of 400 μm. After printing and cleaning, these microstructures could be clearly observed under a high-magnification microscope. After plating, metallic Ni uniformly covered the microstructure surface, yielding a 3D profile consistent with the active precursor.

[0080]

[0079] Figure 8(b) shows that a metal skeletal ball structure having a circular base was also fabricated using this process. This microstructure may be irregularly interconnected, and after plating, the skeleton may be covered with Ni metal. The structure was uniformly plated on the inside and outside and had a metallic luster without under-plating or missing plating.

[0081]

[0080] Figure 8(c) shows a 3D printed Eiffel Tower model in which the tip and middle sections are made of an active precursor material and the remainder is made of standard resin. After plating, Ni metal was precisely deposited on both the tip and middle surfaces of the tower. The original hollow microstructure remained intact, and the interior and exterior of the central hollow structure of the tower were covered with Ni metal having a metallic luster. The fabrication of these multi-material nested parts can demonstrate the capabilities of the MM-DLP3DP described herein.

[0082]

[0081] Furthermore, Figure 8(d) shows a multi-material five-faced component having a specific metal topology distributed on four faces. This structure is very complex, with the metal parts and resin substrates nested to one another, with both interlayer and intralayer nesting present. Despite this complexity, clear boundaries are evident between these parts of the component, confirming that precise selective metallization was achieved. There was a uniform plating distribution, and no Ni plating runoff or contamination.

[0083]

[0082] Figure 8(e) shows a dome structure having six curved metal bands uniformly distributed around its surface, and Figure 8(f) shows a U-tube component having an internal hexagonal mesh made of Ni. The U-tube component with the internal mesh structure shown in Figure 8(f) is particularly difficult to fabricate by most other manufacturing techniques. This highly complex component could not be fabricated by conventional methods using laser etching or 3DP, but could be obtained based on slicing and material switching that allowed for the deposition of an active precursor inside the U-tube. During the ELP process, a plating solution was flowed through the tubular portion, allowing for the formation of a mesh within the cavity by Ni deposition. The right side of this figure shows the intricate structure of the metal mesh after removal from the component. The mesh thickness was 1 mm and contained hexagonal holes, each with an inner diameter of 500 μm.

[0084]

[0083] Furthermore, Figure 8(g) shows a double-layered 3D hollow component in which a large sphere (radius 15 mm) with a triangular hollow hole encloses a small sphere (radius 8 mm) with a regular hexagonal hollow hole. In this component, the plating solution enters through the hole of the outer large sphere, so that selective Ni deposition on the inner small sphere can be successfully achieved. The magnified image (right side of Figure 8(g)) shows the metallic luster of the inner sphere and indicates a good Ni coating. These two components demonstrate the possibility of manufacturing articles with complex internal metallic structures and thus expand the potential applications of this technology.

[0085]

[0084] Flexible 3D electronic devices can also be manufactured using various embodiments. This surface-molded 3DP process does not require a support to obtain the desired flexible structure, thus maintaining a success rate in manufacturing flexible parts. Figure 8(h) shows a flexible carbon nanotube structure in which its central portion is selectively applied using ELP. The high-resolution image shows the bonding between the metal and resin in this article. The metal plating is clearly uniformly distributed, and the boundaries between the different materials are well defined, demonstrating the effective formation of a flexible metal-plastic composite structure using this method. After being subjected to stress, the Ni metal plating remained intact and did not break. Figure 8(i) shows a flexible, wearable hoop-shaped structure. The magnification shows the precise deposition of metal plating on the surface of the knot. This article was found to be highly flexible, and the metal structure did not break under bending deformation. In addition to the above parts, various 3D stereochemical circuits that replace conventional PCB circuits have been designed and fabricated, thus demonstrating the potential of the processes described herein for applications in the field of 3D micro-nanoelectronics.

[0086]

[0085] Figure 9 shows (a) a light-emitting diode (LED) stereo circuit having a complex nickel (Ni) metal wire topology using processes according to various embodiments, (b) a double-layer three-dimensional (3D) circuit structure having a complex three-dimensional (3D) copper wire structure using processes according to various embodiments, which is difficult to manufacture using conventional processes, and (c) a plot of impedance (in ohms or Ω) as a function of frequency (in Hertz or Hz) showing the impedance of nickel (Ni) and copper (Cu) coatings formed using processes according to various embodiments.

[0087]

[0086] Figure 9(a) is a diagram and photographic image of a light-emitting diode (LED) circuit having an irregular 3D structure. The circuit board model in the figure shows that the substrate has an irregular surface profile and the wires have a complex 3D alignment. After printing, soldering, and powering up at 3.3V, the LED was found to function at a normal level of brightness. From this result, it was confirmed that the metal wire structure distributed on the substrate is suitably conductive. Figure 9(b) shows a double-layer 3D circuit having a through-hole structure with a conductor width of 800 μm. The diameter of the through-hole was 500 μm, and the inner wall was covered with copper (Cu) metal connecting the inner and outer layers of the circuit. This circuit has a complex 3D wire distribution, which reduced the size of the device and increased the electron transmission efficiency compared to a standard circuit. These improvements are expected to increase the degree of integration in 3D electronic devices and may have numerous practical applications. Figure 9(c) shows a plot summarizing the impedance characteristics of Cu and Ni plating obtained using the process described herein, confirming that the resulting 3D metal wires exhibited conductivity that met the requirements for use in electronic devices.

[0088]

[0087] To investigate the precision and resolution achievable by selective metallization, sample parts with very small components were also designed and manufactured. Figure 10 shows (a) nickel (Ni) plated structures with widths of 1 mm, 500 μm and 100 μm, as well as 50 μm and 40 μm, formed by processes according to various embodiments, and (b) circuit board components with a width of 1 mm incorporating 500 μm copper wires, formed by processes according to various embodiments. Figure 10(a) shows images of Ni wires with widths of 1 mm, 500 μm, 100 μm, 50 μm and 40 μm. High-magnification microscopy showed that Ni was precisely distributed on these active precursor wires, thus demonstrating the exceptional resolution of the printing method and the effectiveness of selective metal deposition. The Cu plating on the circuit board shown in Figure 10(b) shows that various embodiments can provide a manufacturing resolution of at least 40 μm, sufficient to meet the processing requirements of most electronic products.

[0089]

[0088] Microscopic characterization of 3D selective metal topology

[0090]

[0089] The effectiveness of the ELP induced by the active precursor and the quality of the resulting plating were evaluated by preparing samples with dimensions of 20 mm (length) × 10 mm (width) × 5 mm (height). These test specimens had planar, circular, regular hexagonal, and annular grooved micro-nanostructures with a metallic coating.

[0091]

[0090] Figure 11 shows (a) a standard flat nickel (Ni) plating according to various embodiments, (b), (c) scanning electron microscope (SEM) images of the area shown in (a) at different magnifications according to various embodiments, (d) nickel (Ni) plating on the surface of a circular microstructure according to various embodiments, (e), (f) scanning electron microscope (SEM) images of the area shown in (d) at different magnifications according to various embodiments, (g) nickel (Ni) plating on the surface of an annular groove microstructure according to various embodiments, (h), (i) Scanning electron microscope (SEM) images of the area shown in (g) at different magnifications according to various embodiments, (j) Nickel (Ni) plating on the surface of a regular hexagonal microstructure according to various embodiments, (k) to (l) Scanning electron microscope (SEM) images of the area shown in (j) at different magnifications according to various embodiments, (m) Flexible sample having nickel (Ni) plating, and (n) to (o) Scanning electron microscope (SEM) images of the area shown in (m) at different magnifications according to various embodiments.

[0092]

[0091] Figures 11(a) to (c) show the results of microscopic characterization of a planar sample after a 5-minute plating process. The sample is uniformly covered with Ni, and metallic luster can be observed in the low-magnification optical microscope image (right side of Figure 11(a)). The SEM image acquired with a 100 μm scale bar shows the surface profile of the Ni layer, which is flat in most places and coincides with the planar profile of the active precursor. High local Pd 2+Several small protrusions are evident due to the accumulation of Ni metal caused by the concentration. Higher magnification shows that the Ni metal particles are densely packed together with a more uniform distribution of crystals and less discontinuity. Figures 11(d)–(f) show images of specimens obtained after plating a circular surface with a radius of 200 μm and a depth of 200 μm for 6 minutes.

[0093]

[0092] Figures 11(g) to (i) show the plating on the surface of an annular groove with a width of 200 μm and a depth of 200 μm, and Figures 11(j) to (l) show images of plated hexagonal microstructures with an inner radius of 200 μm and a depth of 200 μm. All three parts show a complete and uniform plating with metallic luster. The SEM image with a 100 μm scale bar shows that all Ni metal particles grew uniformly along the surface profile. The plating does not obscure the original surface structure due to uneven thickness, again demonstrating the uniformity of the plating. The SEM image with a 500 nm scale bar clearly shows the morphology and distribution of Ni metal particles. The distribution of Ni crystals on the surface of these microstructure samples was more irregular than on the planar specimen, but still dense. In the active precursor region, Pd 2+ Although ions were embedded in the cured resin, the intermolecular bonding interactions in the flexible resin were not as strong in these resins compared to the rigid resin after curing. Therefore, Pd in ​​the flexible active precursor 2+Ions precipitated more readily during plating, requiring shorter plating times. Figures 11(m)-(o) show the results of 3 minutes of Ni plating on a flexible active precursor specimen. The resulting metallized microstructure not only enhanced the functionality of the part but also strengthened the bond between the plating and the substrate. Tape testing showed that the Ni metal on the microstructured surface exhibited a higher bonding strength compared to the metal on the flat surface, as a result of the higher roughness associated with the microstructure. Compared to the rigid sample, the flexible sample showed a more consistent plating with higher integrity, and 100 μm scale bar SEM observation showed that the flexible sample had a much rougher surface. This phenomenon was attributed to corrosion of the flexible surface by the acidic components of the plating solution. Corrosion was also evident in 500 nm scale bar SEM images, which show a significant increase in the number of Ni metal particles in the same area with continuous dense clusters of crystals. This indicates that when the sample was unintentionally roughened, more Pd 2+ This is because the ions were exposed.

[0094]

[0093] Various embodiments may include incorporating catalyst seeds into a standard resin, which allows for obtaining a metal layer with higher confinement and bonding strength. Ni-plated samples were treated with a focused ion beam to obtain cross-sections that allowed for better inspection of the microstructure at the metal-resin junction. Subsequently, analysis was performed by transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). Figure 12 shows (a) cross-sectional transmission electron microscopy (TEM) images showing the resin layer, bonding layer and nickel layer of the composite structure according to various embodiments, (b) energy-dispersive X-ray spectroscopy (EDS) images showing the distribution of iron according to various embodiments, (c) energy-dispersive X-ray spectroscopy (EDS) images showing the distribution of palladium according to various embodiments, and (d) energy-dispersive X-ray spectroscopy (EDS) images showing the distribution of nickel according to various embodiments.

[0095]

[0094] Figure 12(a) shows a TEM image acquired at the boundary between the resin and the Ni metal layer. The cross section shows the Ni metal layer, bonding layer, and resin layer after plating. Figure 12(b) shows the distribution of carbon along the cross section including the resin boundary. Carbon was more abundant in the resin layer and significantly less in the intermediate layer, so that the separation between the two phases of the resin layer and the intermediate layer closely matches the image shown in Figure 12(a). This result supports the presence of a bonding layer. During the ELP process, sodium hypophosphite in the plating solution absorbs Pd attached to the surface. 2+ The ions were reduced to Pd particles. The Pd in ​​the intermediate layer catalyzed the deposition of Ni, causing the Ni metal to migrate into the resin and create an embedded Ni intermediate layer within the material. This effect improved the adhesion of the Ni plating.

[0096]

[0095] 3D printed metal-plastic composite parts for electronic devices

[0097]

[0096] Various embodiments may relate to combining non-metallic materials having different functions with a specific metal pattern in order to produce metal-plastic composite parts.

[0098]

[0097] 3D Printed Strain Gauge

[0099]

[0098] Metal-based resistance strain gauges operate on the principle of the resistance strain effect. Specifically, when a Cu wire is subjected to stress, its resistance changes in proportion to the degree of stretching or compression. In conventional strain gauges, the resistance measuring grid is usually laminated between a carrier and a cover film, and this foil strain gauge is bonded to the component being evaluated using an adhesive. The strain of the component is transmitted to the measuring grid through the two intermediate layers. In principle, the measuring grid should be placed as close as possible to the surface of the component to avoid force transmission losses. In such devices, variations in the bonding thickness are reflected in the degree of force transmission, which means that the response of the strain gauge may change.

[0100]

[0099] Various embodiments may relate to printing strain gauges onto an object to be measured. Various embodiments may allow printing strain gauges inside complex parts. This not only ensures consistent mechanical deformation between the strain gauge and the object being measured, but can also allow for the design and manufacture of specific strain gauges that match the actual 3D shape of the object. Figure 13 shows (a) schematic diagrams of three-dimensional (3D) printed integrated strain gauges on an object being measured according to various embodiments, (b) images of strain gauges according to various embodiments and schematic diagrams relating to the measurement of strain gauges according to various embodiments, (c) images showing the bending deformation of the gauge under stress according to various embodiments, (d) plots of voltage (in volts or V units) as a function of load (in grams or g units) showing the voltage measurement characteristics of the strain gauge according to various embodiments, (e) plots of strain as a function of load (in grams or g units) showing the strain characteristics of the strain gauge according to various embodiments calculated from experimental data, and (f) plots of deformation (in millimeters or mm units) as a function of load (in grams or g units) showing experimental deformation data of the strain gauge according to various embodiments.

[0101]

[0100] Figure 13(a) shows strain gauges in various embodiments integrated with the object being measured. The overall part is a rectangular parallelepiped with an opening, and the strain gauge is located inside the base. The electrical signal generated when the internal strain gauge deforms is extracted through the opening in the device. Figure 13(b) is an image showing the structure of the internal strain gauge. Metal electrodes with a pitch and width of 500 μm can be formed using 3D printing and copper (Cu) plating processes. When the object being tested is subjected to force, the strain gauge is bent and deformed, and its resistance fluctuates because the total length of the through-electrode changes. By measuring the change in voltage, the strain, and therefore the amount of deformation, could be calculated. Figure 13(c) provides a photographic image of the strain gauge after deformation. Because an acrylic UV resin was used, the strain gauge was highly flexible and did not break when bent. Figure 13(d) plots the voltage generated by the strain gauge as a function of load, obtained using a star circuit. Figures 13(e) to (f) summarize the calculated strain and deformation values, respectively. When the load is 10g, the experimentally obtained sensor strain value is 0.003. This data is in essentially agreement with the results of the simulation calculation (upper left corner of Figure 13(e)) used to verify the effectiveness of the sensor. Therefore, strain measurements can be performed using this device while compensating for variations in temperature and material properties.

[0102]

[0101] 3D Printed Piezoelectric Sensor

[0103]

[0102] Various embodiments can enable the construction of metal wires on the surface of various functional materials. In various embodiments, polymer polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) can be added to an elastic photocurable resin to produce a piezoelectric material which can also be used as an active precursor. Figure 14 shows (a) a schematic diagram illustrating the operating principle of a three-dimensional (3D) printed piezoelectric sensor according to various embodiments, (b) an image showing the piezoelectric sensor according to various embodiments bent at bending angles of 30°, 60°, 90° and 120°, (c) a plot of voltage (in volts or V) as a function of time (in seconds or s) showing the voltage waveforms generated by the piezoelectric sensor according to various embodiments at 30°, 60°, 90° and 120°, and (d) a plot of voltage (in volts or V) as a function of deformation (in nanometers or nm) showing the voltage generated by the piezoelectric sensor in a tensile state according to various embodiments. The 3D printed piezoelectric sensor includes a thin film substrate made of piezoelectric material and comb-tooth electrodes. When this type of sensor is subjected to an external force along its sensitivity axis, charges of opposite polarity are generated on two adjacent electrodes corresponding to a charge source (i.e., electrostatic electromotive force). The piezoelectric effect allows the device to sense deformation and thus can be used to measure deformation, strain, angular change, and other variables. Figure 14(b) provides photographic images showing the device bent at various angles, and the resulting voltage values ​​are shown in the oscilloscope trace in Figure 14(c). Figure 14(d) shows a plot illustrating the piezoelectric effect of the sensor in an extended state. As the amount of deformation increased (i.e., the length of the central axis of the upper surface increased), the voltage generated by the piezoelectric effect also increased. This voltage directly correlated with specific variables, and with the support of additional filtering and amplification circuits, accurate measurements could be provided. Using this principle, accurate measurement of specific physical quantities can be achieved. Compared to conventional piezoelectric sensors, piezoelectric sensors made by 3DP may require a less complex manufacturing process, which can be integrated with the manufacturing process of the object being inspected, enabling a wider range of applications.

[0104]

[0103] Wearable 3D Printed Flexible ECG Electrode

[0105]

[0104] An electrocardiogram (ECG) can provide information about the electrical activity of the heart and is widely used in the diagnosis and analysis of many diseases. Typically, a complete ECG measurement system consists mainly of electrodes, digital processing circuits, and data analysis terminals. Of these, electrodes can be a critical component that affects the quality of the electrical signals received from the heart. Various embodiments may relate to the formation of wearable, flexible, 3D-printed ECG electrodes.

[0106]

[0105] Figure 15 shows (a) a schematic diagram of a measurement system including three-dimensional (3D) electrocardiogram (ECG) electrodes formed according to various embodiments, (b) an image showing the device components of the system including electrodes formed according to various embodiments, (c) a plot showing five electrocardiogram (ECG) signals measured by electrodes formed according to various embodiments based on random measurements of a stationary subject, and (d) a plot showing electrocardiogram (ECG) signals measured by electrodes formed according to various embodiments based on measurements when the subject is swinging its arm, clicking a computer mouse, and writing.

[0107]

[0106] The measurement system shown in Figure 15(a) can use a dual-lead measurement method in which a host ECG electrode and a secondary ECG electrode can be worn on the subject's right and left wrists, respectively. The electrodes can acquire ECG signals and transmit the acquired signals to a computer via a Bluetooth module attached to the host ECG, which can then process and display the signals. Figure 15(b) shows an image of a 3D printed strap-like wearable device having specially patterned metal electrodes, a circuit for connecting to a portable battery, and a Bluetooth module. This configuration eliminates measurement errors and inconveniences caused by wires and makes it easier to measure ECG signals while the subject is moving. Figure 15(c) shows plots of five different ECG signals obtained using the proposed ECG electrodes when the subject is stationary. The five plots essentially overlap, and the waveforms reflect the expected ECG waveform of a normal human heart. Figure 15(d) shows measurement signals obtained using the ECG electrodes while writing, swinging the arm, and clicking a computer mouse. Compared to conventional ECG, the electrodes offer a simpler measurement process along with efficient output of the obtained data.

[0108]

[0107] Various embodiments may relate to methods for constructing precise metallic patterns on the surface or inside of 3D plastic parts having any complex shape, along with their potential applications. By modifying standard resins, active precursors can be prepared that can facilitate the ELP process. Various embodiments may relate to MM-DLP3DP apparatus for enabling the fabrication of micro-nano 3D metallic plastic component structures. Methods according to various embodiments have been used to fabricate various parts as a demonstration of manufacturing capability. These parts were mainly multi-material and included nested layers containing microporous and small hollow structures with a minimum size of 40 μm. To demonstrate the manufacturing capability of the proposed technology, a 3D circuit with a double-sided structure connected by through holes was fabricated. Furthermore, to demonstrate the advantages of this technology, a series of sensors operating on different principles (3D printed strain gauges, 3D printed piezoelectric sensors, and wearable 3D printed flexible ECG electrodes) were fabricated. Compared with conventional processes, various embodiments enable the integrated fabrication of sensors and objects, and thus can avoid measurement errors and complex processes caused by assembly. As more specialized photocurable resins (such as acrylonitrile-butadiene-styrene, acrylic, and silicon materials) become available, it may become possible to fabricate 3D structures with unique properties. Furthermore, various metals (including Ni, Co, Cu, Au, Ag, and Pt) can potentially be deposited in target patterns by activated precursor-induced plating. This process can enable 3D nesting of various composite materials and therefore has promising applications, particularly in micro-electromechanical systems (MEMS), sensors and robots, wearable devices, and 3D precision electronics.

[0109]

[0108] Although the present invention has been specifically shown and described with reference to certain embodiments, it should be understood by those skilled in the art that various modifications in form and detail can be made without departing from the spirit and scope of the invention as defined by the appended claims. Accordingly, the scope of the invention is indicated by the appended claims and is therefore intended to include all modifications that fall within the same meaning and scope as the claims.

Claims

1. Equipped with a printer, The aforementioned printer is A first pool containing an active solution for forming a first printed portion of a workpiece, wherein the active solution comprises a solvent, an activated seed soluble in the solvent, and a photocurable resin, A second pool containing further photocurable resin for forming a second printed portion of the workpiece, A light source configured to provide light, A mask is positioned such that the light provided by the light source passes through the mask and is irradiated onto the workpiece, Equipped with, The printer further comprises a third pool containing a cleaning solution for cleaning the workpiece, The first printed portion containing the activated seed is configured to form a metal layer by an electroless deposition process, thereby forming a composite structure. The printer further comprises a fourth pool containing a plating bath for forming the metal layer by an electroless deposition process, The cleaning solution comprises ethanol, acetone, and sulfuric acid. Additive manufacturing system for forming composite structures.

2. The aforementioned activation seed is a catalyst or catalyst precursor. The additive manufacturing system according to claim 1.

3. The aforementioned activation seed is palladium metal, silver metal, palladium ion, or silver ion. The additive manufacturing system according to claim 1.

4. The aforementioned photocurable resin and the further photocurable resin are made of the same material. The additive manufacturing system according to claim 1.

5. The aforementioned photocurable resin and the further photocurable resin are made of different materials. The additive manufacturing system according to claim 1.

6. The aforementioned light is ultraviolet light or visible light. The additive manufacturing system according to claim 1.

7. The mask is a liquid crystal display (LCD) mask. The additive manufacturing system according to claim 1.

8. Controllers electrically connected to the first pool, the second pool, the third pool, the light source, and the mask. The additive manufacturing system according to claim 1, further comprising:

9. The controller is configured to control the first pool to deposit the active solution at a predetermined position on the substrate or underlayer to form the first printed portion. The controller is configured to control the mask to generate a first masking pattern. The controller is further configured to control the light source to irradiate the first printed portion with light through the first masking pattern, thereby curing at least one slice of the first printed portion. The controller is further configured to control the third pool to distribute the cleaning solution for cleaning the first printed portion and to remove any remaining uncured slices from the first printed portion. The controller is also configured to control the second pool to deposit the further photocurable resin at another predetermined location on the substrate or the underlayer to form the second printed portion. The controller is also configured to control the mask to generate a second masking pattern. The controller is also configured to control the light source to irradiate the second printed portion with light through the second masking pattern, thereby curing at least one slice of the second printed portion. The controller is further configured to control the third pool to distribute the cleaning solution for cleaning the second printed portion and to remove any remaining uncured slices from the second printed portion. The additive manufacturing system according to claim 8.

10. The controller is configured to control the first pool to deposit the active solution onto the substrate or underlayer to form the first printed portion. The controller is configured to control the mask to generate a first masking pattern. The controller is further configured to control the light source to irradiate the first printed portion with light through the first masking pattern, thereby curing at least one slice of the first printed portion to form a cured slice of the first printed portion, the cured slice of the first printed portion forming a first layer. The controller is further configured to control the third pool to distribute the cleaning solution for cleaning the first printed portion and to remove any remaining uncured slices from the first printed portion. The controller is also configured to control the second pool to deposit the further photocurable resin on the cured slice of the first printed portion to form the second printed portion. The controller is also configured to control the mask to generate a second masking pattern. The controller is further configured to control the light source to irradiate the second printed portion with light through the second masking pattern, thereby curing at least one slice of the second printed portion, the cured slice of the second printed portion forming a second layer on the first layer, The controller is also configured to control the third pool to distribute the cleaning solution for cleaning the first and second printed portions and to remove any remaining uncured slices from the second printed portion. The additive manufacturing system according to claim 8.

11. One or more additional pools containing the cleaning solution for cleaning the workpiece. The additive manufacturing system according to claim 1, further comprising:

12. The aforementioned metal layer includes a metal or a metal alloy. The additive manufacturing system according to claim 1.

13. The metal layer includes an alloy containing nickel metal, copper metal, gold metal, or any combination thereof. The additive manufacturing system according to claim 1.

14. A step of providing a printer, wherein the printer A first pool containing an active solution for forming a first printed portion of a workpiece, wherein the active solution comprises a solvent, an activated seed soluble in the solvent, and a photocurable resin, A second pool containing further photocurable resin for forming a second printed portion of the workpiece, Steps including, A step of providing a light source configured to provide light, The steps include: positioning the mask so that the light provided by the light source passes through the mask and is irradiated onto the workpiece; Includes, The printer further comprises a third pool containing a cleaning solution for cleaning the workpiece, The first printed portion containing the activated seed is configured to form a metal layer by an electroless deposition process, thereby forming a composite structure. The printer further comprises a fourth pool containing a plating bath for forming the metal layer by an electroless deposition process, The cleaning solution comprises ethanol, acetone, and sulfuric acid. A method for forming an additive manufacturing system for forming a composite structure.

15. A step of depositing an active solution containing a solvent, an activated seed soluble in the solvent, and a photocurable resin from a first pool of a printer in an additive manufacturing system to form a first printed portion of a workpiece, The steps include: depositing further photocurable resin from the second pool of the printer in the additive manufacturing system to form a second printed portion of the workpiece; The steps include: irradiating the workpiece with light provided by a light source through a mask; The steps include distributing a cleaning solution for cleaning the workpiece from the third pool of the printer in the additive manufacturing system, The steps include: using the plating bath contained in the fourth pool of the printer of the additive manufacturing system, forming a metal layer on the first printed portion by an electroless deposition process due to the activated seed contained in the first printed portion, thereby forming a composite structure; Includes, A method for forming a composite structure in which the cleaning solution contains ethanol, acetone, and sulfuric acid.

16. The activation seed is a catalyst or a catalyst precursor. The method according to claim 15.

17. The aforementioned photocurable resin and the further photocurable resin are made of the same material. The method according to claim 15.

18. The aforementioned photocurable resin and the further photocurable resin are made of different materials. The method according to claim 15.

19. The aforementioned light is ultraviolet light or visible light. The method according to claim 15.

20. The mask is a liquid crystal display (LCD) mask. The method according to claim 15.

21. The activated solution is deposited at a predetermined position on the substrate or underlayer to form the first printed portion. The method includes the step of generating a first masking pattern using the mask, The light is shone through the first masking pattern onto the first printed portion, thereby curing at least one slice of the first printed portion. The cleaning solution is distributed to clean the first printed portion and remove any remaining uncured slices from the first printed portion. The further photocurable resin is deposited at another predetermined location on the substrate or the underlayer to form the second printed portion. The method includes the step of generating a second masking pattern using the mask, The light is shone through the second masking pattern onto the second printed portion, thereby curing at least one slice of the second printed portion. The cleaning solution is distributed to clean the second printed portion and remove any remaining uncured slices from the second printed portion. The method according to claim 15.

22. The activated solution is deposited on the substrate or underlayer to form the first printed portion. The method includes the step of generating a first masking pattern using the mask, The light is irradiated onto the first printed portion through the first masking pattern, thereby curing at least one slice of the first printed portion to form a cured slice of the first printed portion, and the cured slice of the first printed portion forms a first layer. The cleaning solution is distributed to clean the first printed portion and remove any remaining uncured slices from the first printed portion. The further photocurable resin is deposited on the cured slice of the first printed portion to form the second printed portion. The method includes the step of generating a second masking pattern using the mask, The light is shone through the second masking pattern onto the second printed portion, thereby curing at least one slice of the second printed portion, and the cured slice of the second printed portion forms a second layer on the first layer. The cleaning solution is distributed to clean the first printed portion and the second printed portion and to remove any remaining uncured slices from the second printed portion. The method according to claim 15.

23. The aforementioned metal layer includes a metal or a metal alloy. The method according to claim 15.

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