Liquid metal direct writing circuit printing method and device

Abstract

The invention discloses a liquid metal direct-writing circuit printing method and device, and relates to the technical field of circuit direct-writing printing.The liquid metal direct-writing circuit printing method comprises the steps that a substrate is prepared; preparing a circuit: printing the circuit on the substrate and placing an electronic element; preparing a packaging layer: preparing the packaging layer on the surface of one side, far away from the substrate, of the circuit and the electronic element; wherein the shapes of the substrate and the packaging layer are the same as the shape of the overall structure of the circuit and the electronic element. The invention also provides a liquid metal direct-writing circuit printing device, the shapes of the substrate and the packaging layer prepared by the liquid metal direct-writing circuit printing method and device provided by the invention are the same as the shape of the overall structure of the circuit and the electronic component, and an overall packaging means in the prior art is abandoned; the influence of overall packaging on the tensile property of the circuit packaging structure is avoided, and the tensile property of the circuit packaging structure is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit direct writing printing, and in particular to a liquid metal direct writing circuit printing method and device. Background Art

[0002] Liquid metal direct-write circuit printing is a digital, maskless electronic manufacturing technology that deposits liquid metal (melted at room temperature or low temperature, where liquid metal refers only to room temperature liquid metal, gallium, and gallium-based alloys) into a designed circuit pattern in a controllable manner, without the need for traditional etching or photolithography processes. It is suitable for rapid prototyping of circuits on flexible, curved, or special-shaped substrates. Existing liquid metal direct-write circuit printing methods typically use packaging methods that directly pour uncured elastomeric material and then cure it, which has low controllability and the overall packaging will also have a certain impact on stretchability. Summary of the Invention

[0003] The purpose of the present invention is to provide a liquid metal direct writing circuit printing method and device to solve the problems existing in the above-mentioned prior art and make the direct writing circuit have good stretchability.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The present invention provides a liquid metal direct writing circuit printing method, comprising:

[0006] preparing a substrate;

[0007] Preparing the circuit: printing the circuit on the substrate and placing electronic components;

[0008] Preparing a packaging layer: preparing a packaging layer on a surface of the circuit and electronic components away from the substrate;

[0009] The shapes of the substrate and the packaging layer are the same as the shapes of the overall structure of the circuit and electronic components.

[0010] Preferably, for a complex circuit composed of multiple layers of circuits, the steps of preparing the circuit and preparing the packaging layer include:

[0011] S21: Printing a first layer of circuits on the substrate;

[0012] S22: Locally encapsulate the nodes where the printed circuits intersect with circuits in other layers but are not conductive;

[0013] S23: Printing an N-th layer of circuits on the printed circuits and / or the substrate;

[0014] S24: Repeat S22 and S23 until the circuit part is printed;

[0015] S25: preparing an encapsulation layer on the surface of the circuit and electronic components not covered by the encapsulation layer;

[0016] Wherein, the electronic components are placed in corresponding steps according to the setting positions of the electronic components.

[0017] Preferably, in the circuit preparation step, the liquid metal used to print the circuit is a modified liquid metal ink to increase the viscosity of the liquid metal ink.

[0018] Preferably, the liquid metal is mixed with solid particles to increase the viscosity of the metal ink.

[0019] Preferably, the substrate and the encapsulation layer are prepared by printing.

[0020] The present invention also provides a liquid metal direct writing circuit printing device, comprising:

[0021] The substrate and packaging layer preparation assembly is used to prepare a substrate with the same overall structural shape as the circuit and electronic components at the workstation;

[0022] a circuit printing assembly for printing the circuit on the substrate;

[0023] The substrate and packaging layer preparation assembly is also used to prepare a packaging layer on the surface of the circuit and electronic component overall structure on the side away from the substrate. The packaging layer has the same shape as the circuit and electronic component overall structure.

[0024] Preferably, the substrate and encapsulation layer preparation component is a silicone printing component.

[0025] Preferably, a desktop robot is further included, and the desktop robot is used to drive the silicone printing head of the silicone printing assembly and the liquid metal printing head of the circuit printing assembly to move in three-dimensional space.

[0026] Preferably, it further comprises a heating platform and a leveling platform, wherein the heating platform is arranged on the leveling platform, the work station is formed on the heating platform, the heating platform is used to heat the work station, and the leveling platform is used to level the work station.

[0027] Preferably, it also includes an observation camera, which is set to be aimed at the workstation and is used to record the printing process.

[0028] Compared with the prior art, the present invention has achieved the following technical effects:

[0029] First, the shape of the substrate and packaging layer prepared by the liquid metal direct writing circuit printing method and device provided by the present invention is the same as the shape of the circuit and the overall structure of the electronic component, abandoning the overall packaging method in the prior art, avoiding the influence of the overall packaging on the stretchability of the circuit packaging structure, and thus improving the stretchability of the circuit packaging structure.

[0030] Second, in the step of preparing the circuit system, the liquid metal used to print the circuit is a modified liquid metal ink to increase the viscosity of the liquid metal ink, thereby improving the success rate of printing.

[0031] Third, the printing principle is used to prepare the substrate and encapsulation layer, which has high controllability and high success rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 A schematic structural diagram of a liquid metal direct writing circuit printing device provided in an embodiment of the present invention;

[0034] Figure 2 is a block diagram of a control system in an embodiment of the present invention;

[0035] Figure 3 Figure a is a schematic diagram of the base printing step; Figure b is a schematic diagram of the first layer circuit printing step; Figure c is a schematic diagram of the partial packaging step; Figure d is a schematic diagram of the second layer circuit printing step; Figure e is a schematic diagram of the final packaging step; Figure f is a schematic diagram of an example circuit;

[0036] In the figure: 1-desktop robot; 2-microinjection pump fixture; 3-microinjection pump; 4-liquid metal print head; 5-mounting plate; 6-silicone print head fixture; 7-silicone print head; 8-camera fixture; 9-observation camera; 10-light source; 11-heating table; 12-leveling platform; 13-leveling platform connector. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] The following combination Figures 1 to 3 , describing embodiments of the present invention.

[0040] Example 1

[0041] An embodiment of the present invention provides a liquid metal direct writing circuit printing method, comprising:

[0042] preparing a substrate;

[0043] Prepare circuits: Print circuits on substrates and place electronic components;

[0044] Preparation of encapsulation layer: preparation of encapsulation layer on the surface of the circuit and electronic components away from the substrate;

[0045] The shapes of the substrate and encapsulation layer are identical to the shapes of the overall structure of the circuit and electronic components. In some examples, the substrate and encapsulation layer are slightly larger than the circuit and electronic components. Of course, in extreme cases, the shapes of the substrate and encapsulation layer are identical to the shapes and sizes of the overall structure of the circuit and electronic components. In other words, the vertical projection of the overall structure of the circuit and electronic components completely falls on the substrate and encapsulation layer. Preferably, the dimensional difference between the edges of the substrate and encapsulation layer and the edges of the vertical projection of the overall structure of the circuit and electronic components is no more than 5 mm.

[0046] The shape of the substrate and packaging layer prepared by the liquid metal direct-write circuit printing method and device provided by the present invention is the same as the shape of the circuit and the overall structure of the electronic component, abandoning the overall packaging method used in the prior art, avoiding the impact of overall packaging on the stretchability of the circuit packaging structure, and thus improving the stretchability of the circuit packaging structure. In other words, the substrate and packaging layer provided by the application have the same hollow portion as the circuit, thus making the substrate and packaging layer a discontinuous structure, thereby improving the stretchability of the overall structure.

[0047] It should be noted that the substrate and packaging layer mentioned in this application can be collectively referred to as a packaging structure.

[0048] In some embodiments, the substrate and the encapsulation layer have the same size. Of course, in some examples, the encapsulation layer may be slightly smaller than the substrate.

[0049] Complex circuits often require multi-layer design to improve space utilization. Existing technologies cannot easily print and package liquid metal multi-layer circuits. In multi-layer circuits, there are various situations where two adjacent layers of circuits cross but are not conductive, or cross-conductive. The present invention provides the following embodiments for preparing complex circuits. Specifically, for a complex circuit composed of multiple layers of circuits, the steps of preparing the circuit and the packaging layer include:

[0050] S21: Printing the first layer of circuits on the substrate;

[0051] S22: Locally encapsulate the nodes where the printed circuits intersect with circuits in other layers but are not conductive;

[0052] S23: Printing an N-th layer of circuits on the printed circuits and / or substrate;

[0053] S24: Repeat S22 and S23 until the circuit part is printed;

[0054] S25: preparing an encapsulation layer on surfaces of the circuits and electronic components not covered with the encapsulation layer;

[0055] The electronic components are placed in corresponding steps according to their placement positions.

[0056] For complex circuits, this embodiment can realize the production of two types of line crossing situations: cross-conduction nodes and cross-insulation nodes, thereby realizing multi-layer flexible circuit printing, providing a technical option for the production of more complex flexible stretchable circuits.

[0057] It can be understood that in the above-mentioned step S22, when local encapsulation is performed, at least the nodes where the printed circuits intersect with the next layer of circuits but are not conductive are encapsulated. Of course, when some printed circuits will never intersect with other circuits to be printed, encapsulation can be performed in any local encapsulation link or the last encapsulation link.

[0058] In some embodiments, the packaging layer and the substrate are both made of elastomeric materials, such as silicone, so as to maintain the flexibility of the overall structure after packaging.

[0059] Taking into account the technical problem in the prior art that droplet accumulation is very likely to occur when extruding liquid metal due to its high surface tension and low viscosity, which affects the printing quality and the printing stability needs to be improved, the present invention also provides the following embodiment. In this embodiment, in the circuit preparation step, the liquid metal used for printing the circuit is a modified liquid metal ink to increase the viscosity of the liquid metal ink.

[0060] This embodiment can improve the success rate of direct-write printing circuits.

[0061] Specifically, liquid metal is added to the metal ink to modify the metal ink and thereby increase the viscosity of the metal ink.

[0062] The solid particles can be metal particles or non-metal particles. Metal particles can be copper particles, nickel particles, silver particles, etc.; non-metal particles can be quartz powder, etc.

[0063] In some embodiments, the substrate and the encapsulation layer are prepared by printing.

[0064] This embodiment adopts the printing principle to prepare the substrate and the encapsulation layer, which has high controllability and high success rate.

[0065] Example 2

[0066] like Figures 1 and 2 As shown, the present invention also provides a liquid metal direct writing circuit printing device, comprising: a substrate and encapsulation layer preparation component, and a circuit printing component. The substrate and encapsulation layer preparation component is used to prepare a substrate with the same shape as the overall structure of the circuit and electronic components at a work station; the circuit printing component is used to print the circuit on the substrate; the substrate and encapsulation layer preparation component is also used to prepare an encapsulation layer on the surface of the side of the overall structure of the circuit and electronic components away from the substrate, and the encapsulation layer has the same shape as the overall structure of the circuit and electronic components. In some examples, the size of the substrate and the encapsulation layer is slightly larger than the circuit and electronic components. Of course, in extreme cases, the shape of the substrate, the encapsulation layer, and the shape and size of the overall structure of the circuit and electronic components are the same.

[0067] The shape of the substrate and packaging layer prepared by the liquid metal direct-writing circuit printing device provided in the embodiment of the present invention is the same as the shape of the circuit and the overall structure of the electronic component, abandoning the overall packaging method in the prior art, avoiding the influence of the overall packaging on the stretchability of the circuit packaging structure, and thus improving the stretchability of the circuit packaging structure.

[0068] In some embodiments, the substrate and encapsulation layer preparation component is a silicone printing component.

[0069] This embodiment adopts the printing principle to prepare the substrate and the encapsulation layer, which has high controllability and high success rate.

[0070] In some embodiments, the present invention further includes a desktop robot 1, which is used to drive the silicone printing head 7 of the silicone printing component and the liquid metal printing head 4 of the circuit printing component to move in three-dimensional space.

[0071] This embodiment realizes the automatic printing of the packaging layer, substrate and circuit. Specifically, before work, it is necessary to design the movement trajectory of the print head of the silicone printing component and the print head of the circuit printing component according to the structure of the circuit, and then convert it into a movement trajectory in the control system. Then, the control system controls the two print heads to work separately according to the designed movement trajectory.

[0072] This embodiment can switch between the liquid metal print head 4 and the silicone print head 7 to perform printing work.

[0073] In some embodiments, the embodiments of the present invention further include a heating platform 11 and a leveling platform 12. The heating platform 11 is arranged on the leveling platform 12. The workstation is formed on the heating platform 11. The heating platform 11 is used to heat the workstation, and the leveling platform 12 is used to level the workstation.

[0074] The heating platform 11 in this embodiment is used to heat the silicone during printing to accelerate its curing.

[0075] In some embodiments, the present invention further includes an observation camera 9, which is aligned with the workstation and is used to record the printing process.

[0076] In some embodiments, the circuit printing component includes, in addition to the liquid metal print head 4, a microinjection pump 3 and a liquid metal storage tank. The microinjection pump 3 is used to pump the liquid metal stored in the liquid metal storage tank into the liquid metal print head 4, and print the liquid metal onto the substrate through the liquid metal print head 4.

[0077] The silicone printing assembly uses an air pressure regulating system to drive the silicone to be extruded from the silicone printing head 7. This is a mature technology and will not be described in detail here.

[0078] It should be noted that the liquid metal print head 4 and the silicone print head 7 are fixed to the driving end of the desktop robot 1 through respective clamps.

[0079] In some embodiments, the desktop robot 1 has one or two driving ends. When it has one driving end, the liquid metal print head 4 and the silicone print head 7 are fixed together on the driving end. The desktop robot 1 drives the liquid metal print head 4 and the silicone print head 7 to work in different time periods according to a preset trajectory. When it has two driving ends, the liquid metal print head 4 and the silicone print head 7 are fixed on the two driving ends respectively. The two driving ends can work at the same time. At this time, it is necessary to avoid interference between the movements of the two print heads by designing the movement trajectory and time difference.

[0080] Specifically, such as Figure 1As shown, the desktop robot 1 shown in this embodiment has a driving end, on which a mounting plate 5 is fixedly provided. The mounting plate 5 is provided with an observation camera 9, a microinjection pump 3 and a silicone print head 7 through a camera clamp 8, a microinjection pump clamp 2 and a silicone print head clamp 6 in sequence. The microinjection pump 3 and the liquid metal print head 4 are connected.

[0081] In some embodiments, the observation camera 9 is provided with a light source 10 for irradiating the workstation.

[0082] In some embodiments, the leveling platform 12 is connected to the tabletop via a leveling platform connector 13 .

[0083] In some embodiments, the control system mainly includes two parts: a microinjection pump control system and an air pressure control system, which are used to control the extrusion printing of liquid metal and silicone respectively. The control system is composed of the following components: Figure 2 The microinjection pump control system consists of a microinjection pump control box, a single-chip microcomputer, and a resistor voltage divider module. Desktop robot 1 sends a 24V high-level signal to the resistor voltage divider module via a terminal block. The resistor voltage divider module reduces the 24V high-level signal to 5V and sends it to the single-chip microcomputer. Signal transmission between the single-chip microcomputer and the microinjection pump control box 3 is achieved via an RS232-to-TTL module. The pneumatic drive system consists of an air compressor, a pressure reducing valve, a digital pressure regulator, a pneumatic solenoid valve, and a switching power supply. The air compressor provides the air source, powering the entire device. A pressure reducing valve, connected to the air compressor, reduces the air source to 0.3 MPa, ensuring safety for subsequent pressure adjustments. A pneumatic solenoid valve, connected between the pressure reducing valve and the digital pressure regulator, controls the opening and closing of the air port via electrical signals, enabling the start and stop of air flow. The digital pressure regulator, connected to the syringe barrel via a syringe adapter, converts linear pressure into uniform thrust, enabling precise adjustment of the air pressure to the syringe barrel, enabling accurate control of the print drive with a resolution of ±1 kPa. A switching power supply powers the digital pressure regulator and pneumatic solenoid valve. All of these connections are made using PU hoses.

[0084] Of course, the circuit printing component and the silicone printing component can adopt any liquid printing device in the prior art as long as it can achieve stable printing of liquid.

[0085] Example 3

[0086] Printing using the above liquid metal direct writing circuit printing method and device Figure 3 The specific steps in Figure f on the left are:

[0087] First, a patterned circuit substrate is printed with silicone. Compared with a whole substrate, a patterned substrate has higher air permeability and stretchability. During the printing process, it is necessary to control the distance between the print head and the substrate (related to the inner diameter of the printing needle used, generally about half of the inner diameter of the needle. For example, when printing with a needle with an inner diameter of 900μm, the distance is selected to be 400-500μm), which has a leveling effect and ensures the flatness of the substrate as much as possible to facilitate the printing of liquid metal; then, the first layer of liquid metal wires is printed on the substrate to complete the cross-conductive nodes and most of the wire lines, leaving the cross-conductive but non-conductive nodes, and placing chips and other electronic components; the cross-conductive but non-conductive nodes are partially encapsulated, and then the second layer of liquid metal wires is printed to complete the conduction of the entire circuit; finally, all liquid metal wires are encapsulated to prevent leakage.

[0088] like Figure 3 As shown, Figure a is a schematic diagram of the base printing step; Figure b is a schematic diagram of the first layer circuit printing step; Figure c is a schematic diagram of the local packaging step; Figure d is a schematic diagram of the second layer circuit printing step; Figure e is a schematic diagram of the final packaging step; Figure f is a schematic diagram of an example circuit.

[0089] In summary, the inventors of this application have found that the existing technology has the following defects: 1. When extruding liquid metal, due to its high surface tension and low viscosity, droplet accumulation is very likely to occur, which affects the printing quality and the printing stability needs to be improved; 2. The packaging method is usually to directly pour the uncured elastomer material and then solidify it, which is not very controllable, and the overall packaging will also have a certain impact on the stretchability; 3. For complex circuits, in order to improve space utilization, the circuit needs to be designed into multiple layers, and the convenient printing and packaging method of liquid metal multi-layer circuits still needs to be explored. The above embodiment of the present invention proposes a liquid metal direct writing circuit printing method and device. Relying on the extrusion direct writing printing principle, the liquid metal and elastomer material print heads can be switched for printing, and the substrate, circuit and packaging layer can be integrated to obtain a substrate-free circuit with only wires and electronic component substrates. For complex circuits, the two print heads can be switched to achieve the production of two types of line crossings: cross-conducting nodes and cross-but-not-conducting nodes, thereby realizing multi-layer flexible circuit printing, providing a technical option for the production of more complex flexible stretchable circuits.

[0090] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A liquid metal direct writing circuit printing method, characterized by: include: preparing a substrate; Preparing the circuit: printing the circuit on the substrate and placing electronic components; Preparing a packaging layer: preparing a packaging layer on a surface of the circuit and electronic components away from the substrate; The shapes of the substrate and the packaging layer are the same as the shapes of the overall structure of the circuit and electronic components.

2. The liquid metal direct writing circuit printing method according to claim 1, characterized in that: For complex circuits consisting of multiple layers of circuits, the steps for preparing the circuit and the packaging layer include: S21: Printing a first layer of circuits on the substrate; S22: Locally encapsulate the nodes where the printed circuits intersect with circuits in other layers but are not conductive; S23: Printing an N-th layer of circuits on the printed circuits and / or the substrate; S24: Repeat S22 and S23 until the circuit part is printed; S25: preparing an encapsulation layer on the surface of the circuit and electronic components not covered by the encapsulation layer; Wherein, the electronic components are placed in corresponding steps according to the setting positions of the electronic components.

3. The liquid metal direct writing circuit printing method according to claim 1, characterized in that: In the circuit preparation step, the liquid metal used to print the circuit is a modified liquid metal ink to increase the viscosity of the liquid metal ink.

4. The liquid metal direct writing circuit printing method according to claim 3, characterized in that: Liquid metal is incorporated into the ink to increase the viscosity of the metal ink.

5. The liquid metal direct writing circuit printing method according to claim 1, characterized in that: The substrate and encapsulation layer are prepared by printing.

6. A liquid metal direct writing circuit printing device, characterized in that: include: The substrate and packaging layer preparation assembly is used to prepare a substrate with the same overall structural shape as the circuit and electronic components at the workstation; a circuit printing assembly for printing the circuit on the substrate; The substrate and packaging layer preparation assembly is also used to prepare a packaging layer on the surface of the circuit and electronic component overall structure on the side away from the substrate. The packaging layer has the same shape as the circuit and electronic component overall structure.

7. The liquid metal direct writing circuit printing device according to claim 6, characterized in that: The substrate and packaging layer preparation component is a silicone printing component.

8. The liquid metal direct writing circuit printing device according to claim 7, characterized in that: It also includes a desktop robot, which is used to drive the silicone printing head of the silicone printing assembly and the liquid metal printing head of the circuit printing assembly to move in three-dimensional space.

9. The liquid metal direct writing circuit printing device according to claim 7, characterized in that: It also includes a heating platform and a leveling platform. The heating platform is arranged on the leveling platform. The workstation is formed on the heating platform. The heating platform is used to heat the workstation, and the leveling platform is used to level the workstation.

10. The liquid metal direct writing circuit printing device according to claim 9, characterized in that: It also includes an observation camera, which is set to be aimed at the workstation and is used to record the printing process.

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