Multi-layer conductive interconnection structure based on liquid metal and flexible circuit
By filling liquid metal droplets on the flexible circuit and blocking it, the problem of poor tensility of conductive interconnections between multi-layer flexible circuits is solved, and stable conductive connections and high conductivity are achieved.
Patent Information
- Application Number
- CN202420523133.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-18
- Publication Date
- 2024-12-31
- Estimated Expiration
- 2034-03-18
AI Technical Summary
The conductive interconnection between existing multi-layer flexible circuits uses conductive tape or conductive paste, resulting in poor stretchability, poor conductivity and poor conductivity.
A multi-layer conductive interconnect structure based on liquid metal and flexible circuit is adopted. By opening through holes on the flexible circuit, liquid metal droplets are poured, and the through holes are blocked with a flexible cover, the conductive connection between the liquid metal conductive layers is realized.
A flexible and stretchable multi-layer conductive interconnection is realized, ensuring conductive stability and high conductivity, and the tension deformation has little impact on resistance.
Smart Images
Figure CN222283558U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of electronic interconnection, and in particular to a multi-layer conductive interconnection structure based on liquid metal and flexible circuits. Background Art
[0002] Electronic interconnection plays an important role in signal transmission in electronic devices and has a very important impact on the performance of electronic circuits. In some cases, the number of components in the circuit is large and the arrangement is complex, which makes it impossible to arrange the interconnection between components in a single-layer circuit, so multi-layer wiring is required.
[0003] In the field of flexible electronics, it is necessary to make conductive interconnections between multiple layers of flexible circuits. Stretchability is an important property of flexible circuits. The commonly used conductive interconnection method between multiple layers of flexible circuits requires the use of conductive tape or conductive paste, but the conductive tape or conductive paste has poor stretchability, which leads to poor conduction stability and poor conductivity at the conductive interconnection between multiple layers of flexible circuits. Utility Model Content
[0004] Based on this, it is necessary to provide a multi-layer conductive interconnection structure based on liquid metal and flexible circuits, in view of the fact that the commonly used conductive interconnection method between multi-layer flexible circuits requires the use of conductive tape or conductive paste, but the conductive tape or conductive paste has poor stretchability, which leads to poor conduction stability and poor conductivity at the conductive interconnection between multi-layer flexible circuits.
[0005] An embodiment of the present application provides a multi-layer conductive interconnect structure based on liquid metal and a flexible circuit, comprising at least two layers of flexible circuits stacked in layers, wherein the flexible circuit comprises a flexible substrate and a liquid metal conductive layer disposed on a surface of the flexible substrate;
[0006] In two adjacent layers of the flexible circuits, the flexible substrate of the first layer of the flexible circuit covers the side of the second layer of the flexible circuit where the liquid metal conductive layer is provided;
[0007] The first layer of the flexible circuit is provided with a through hole, the through hole penetrates the flexible substrate and the liquid metal conductive layer of the first layer of the flexible circuit, and a liquid metal droplet is arranged in the through hole; the first layer of the flexible circuit also includes a flexible cover, the flexible cover is arranged on the surface of the liquid metal conductive layer and blocks the opening of the through hole;
[0008] The liquid metal conductive layer of the first layer of the flexible circuit and the liquid metal conductive layer of the second layer of the flexible circuit are conductively connected via the liquid metal droplets.
[0009] In one embodiment, the flexible substrate is an adhesive substrate, so that the flexible substrate of the first layer of the flexible circuit is bonded to the flexible substrate of the second layer of the flexible circuit.
[0010] In one embodiment, the flexible substrate is a polydimethylsiloxane flexible substrate.
[0011] In one embodiment, the flexible substrate of the first layer of the flexible circuit and the flexible substrate of the second layer of the flexible circuit are bonded together by an adhesive.
[0012] In one embodiment, the through hole is filled with the liquid metal droplets.
[0013] In one embodiment, the material of the liquid metal in the liquid metal conductive layer is gallium, gallium-indium alloy or gallium-indium-tin alloy; the material of the liquid metal in the liquid metal droplet is gallium, gallium-indium alloy or gallium-indium-tin alloy.
[0014] In one embodiment, in the gallium-indium alloy, the mass ratio of gallium to indium is 90.0:10.0 - 75.5:24.5.
[0015] In one embodiment, in the gallium-indium alloy, the mass ratio of gallium to indium is 75.5:24.5.
[0016] In one embodiment, the thickness of the flexible substrate is 0.3 mm to 0.4 mm.
[0017] In one embodiment, the material used for the flexible cover is the same as the material used for the flexible substrate.
[0018] An embodiment of the present application provides a multi-layer conductive interconnection method based on liquid metal and a flexible circuit, which is used to form a multi-layer conductive interconnection structure based on liquid metal and a flexible circuit as described in any of the above embodiments. The method includes the following steps when connecting two adjacent layers of the flexible circuit:
[0019] Opening the through hole on the first layer of the flexible circuit;
[0020] Disposing the flexible substrate of the first layer of the flexible circuit on the liquid metal conductive layer of the second layer of the flexible circuit;
[0021] pouring the liquid metal droplets into the through hole;
[0022] A flexible cover is provided on the surface of the liquid metal conductive layer of the first layer of the flexible circuit to block the opening of the through hole.
[0023] In one embodiment, the through holes are opened on the first layer of the flexible circuit by laser cutting.
[0024] In one embodiment, the through hole is a circular hole; when the thickness of the flexible substrate of the first layer of the flexible circuit is 0.3 mm to 0.4 mm and is a polydimethylsiloxane flexible substrate, a carbon dioxide laser cutting machine is used to cut two circular holes with a diameter of 1 mm, wherein the laser power is 70%, the speed is 60%, the PPI (Pixels Per Inch) is 50%, and the Z-axis cutting depth is set to 0.1 mm.
[0025] In one embodiment, the liquid metal droplets are injected into the through hole by a needle syringe.
[0026] In one embodiment, the step of providing a flexible cover on the surface of the liquid metal conductive layer of the first layer of the flexible circuit is: covering the position where the through hole is provided on the surface of the liquid metal conductive layer of the first layer of the flexible circuit with a mixed solution of polydimethylsiloxane and a curing agent and drying it to form the flexible cover.
[0027] In the above-mentioned multi-layer conductive interconnection structure based on liquid metal and flexible circuit, in two adjacent layers of flexible circuit, the flexible substrate of the first layer of flexible circuit covers the side of the second layer of flexible circuit provided with the liquid metal conductive layer. Since the first layer of flexible circuit is provided with a through hole, the through hole penetrates the flexible substrate and the liquid metal conductive layer of the first layer of flexible circuit, and a liquid metal droplet is provided in the through hole, so that the liquid metal conductive layer of the first layer of flexible circuit and the liquid metal conductive layer of the second layer of flexible circuit can be conductively connected through the liquid metal droplet. Since the flexible cover is provided on the surface of the liquid metal conductive layer of the first layer of flexible circuit and blocks the opening of the through hole, the liquid metal droplet can be sealed in the through hole to prevent leakage. Since the flexible substrate has certain stretchability and flexibility, and the liquid metal has high conductivity and good conductive stability, the tensile deformation has almost no effect on its resistance, so the above-mentioned multi-layer conductive interconnection structure based on liquid metal and flexible circuit can form a stable conductive interconnection while having certain flexibility and stretchability. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 FIG. 1 is a top view of a first layer of flexible circuits in two adjacent layers of flexible circuits according to an embodiment.
[0029] Figure 2 for Figure 1 Cross-sectional view of the structure shown.
[0030] Figure 3 FIG. 1 is a top view of a second layer of flexible circuits in two adjacent layers of flexible circuits according to an embodiment.
[0031] Figure 4 for Figure 3 Cross-sectional view of the structure shown.
[0032] Figure 5 FIG. 1 is a top view of a conductive interconnect structure of two adjacent layers of flexible circuits according to an embodiment.
[0033] Figure 6 for Figure 5 Cross-sectional view of the structure shown.
[0034] Description of reference numerals:
[0035] 1-1, the flexible substrate of the first layer of flexible circuit;
[0036] 1-2, the first layer of liquid metal conductive layer of the flexible circuit;
[0037] 1-3, liquid metal droplets;
[0038] 1-4, flexible cover;
[0039] 2-1, flexible substrate of the second layer flexible circuit;
[0040] 2-2. Liquid metal conductive layer of the second flexible circuit. DETAILED DESCRIPTION
[0041] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.
[0042] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.
[0043] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.
[0044] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0045] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.
[0046] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.
[0047] An embodiment of the present application provides a multi-layer conductive interconnect structure based on liquid metal and flexible circuit, including at least two layers of flexible circuits stacked in layers, specifically two layers, three layers or more layers. The flexible circuit includes a flexible substrate and a liquid metal conductive layer disposed on the surface of the flexible substrate.
[0048] The two adjacent layers of flexible circuits are defined as the first layer of flexible circuits and the second layer of flexible circuits. Figure 1 and Figure 2 As shown, the first layer of the flexible circuit includes a flexible substrate 1-1 and a liquid metal conductive layer 1-2. Figure 3 and Figure 4 As shown, the second layer of the flexible circuit includes a flexible substrate 2-1 and a liquid metal conductive layer 2-2.
[0049] Recombination Figure 5 and Figure 6In two adjacent layers of flexible circuits, the flexible substrate 1-1 of the first layer of flexible circuit covers the side of the second layer of flexible circuit where the liquid metal conductive layer 2-2 is provided.
[0050] The first layer of flexible circuit is provided with a through hole, which passes through the flexible substrate 1-1 and the liquid metal conductive layer 1-2 of the first layer of flexible circuit, and a liquid metal droplet 1-3 is provided in the through hole, so that the liquid metal droplet 1-3 can contact the liquid metal conductive layer 1-2 of the first layer of flexible circuit, and then the liquid metal droplet 1-3 can be electrically connected to the liquid metal conductive layer 1-2 of the first layer of flexible circuit. Since the flexible substrate 1-1 of the first layer of flexible circuit is arranged on the liquid metal conductive layer 2-2 of the second layer of flexible circuit, the liquid metal droplet 1-3 can also contact the liquid metal conductive layer 2-2 of the second layer of flexible circuit, and then the liquid metal droplet 1-3 can be electrically connected to the liquid metal conductive layer 2-2 of the second layer of flexible circuit. In this way, the liquid metal conductive layer 1-2 of the first layer of flexible circuit and the liquid metal conductive layer 2-2 of the second layer of flexible circuit can be electrically connected through the liquid metal droplet 1-3.
[0051] The first layer of flexible circuit also includes a flexible cover 1-4, which is arranged on the surface of the liquid metal conductive layer 1-2 of the first layer of flexible circuit and blocks the opening of the through hole, so that the liquid metal droplet 1-3 can be sealed in the through hole to prevent leakage.
[0052] It can be understood that when the flexible substrate 1-1 of the first layer flexible circuit covers the side of the second layer flexible circuit provided with the liquid metal conductive layer 2-2, it can block the end of the through hole away from the flexible cover 1-4 to prevent the liquid metal droplets 1-3 from leaking out from the end of the through hole away from the flexible cover 1-4.
[0053] The multi-layer conductive interconnect structure based on liquid metal and flexible circuits comprises at least two layers of flexible circuits stacked in layers. In the two adjacent layers of flexible circuits, the flexible substrate 1-1 of the first layer of flexible circuit covers the side of the second layer of flexible circuit provided with the liquid metal conductive layer 2-2. Since the first layer of flexible circuit is provided with a through hole, the through hole penetrates the flexible substrate 1-1 and the liquid metal conductive layer 1-2 of the first layer of flexible circuit, and a liquid metal droplet 1-3 is provided in the through hole, so that the liquid metal conductive layer 1-2 of the first layer of flexible circuit and the liquid metal conductive layer 2-2 of the second layer of flexible circuit can be conductively connected through the liquid metal droplet 1-3. Since the flexible cover 1-4 is provided on the surface of the liquid metal conductive layer 1-2 of the first layer of flexible circuit and blocks the opening of the through hole, the liquid metal droplet 1-3 can be sealed in the through hole to prevent leakage. Since the flexible substrate has certain stretchability and flexibility, and the liquid metal has high electrical conductivity and good conductive stability, tensile deformation has almost no effect on its resistance. Therefore, the above-mentioned multilayer conductive interconnect structure based on liquid metal and flexible circuit can form a stable conductive interconnect while having certain flexibility and stretchability.
[0054] In one embodiment, the through hole is filled with liquid metal droplets 1-3, so that the liquid metal conductive layer 1-2 of the first layer of the flexible circuit and the liquid metal conductive layer 2-2 of the second layer of the flexible circuit can form a more reliable electrical contact with the liquid metal droplets 1-3 respectively, thereby enabling the liquid metal conductive layer 1-2 of the first layer of the flexible circuit and the liquid metal conductive layer 2-2 of the second layer of the flexible circuit to achieve a more reliable conductive connection through the liquid metal 1-3.
[0055] In one embodiment, the flexible substrate is an adhesive substrate, so that when the flexible substrate 1-1 of the first layer of flexible circuit covers the side of the second layer of flexible circuit provided with the liquid metal conductive layer 2-2, the flexible substrate 1-1 of the first layer of flexible circuit contacts the flexible substrate 2-1 of the second layer of flexible circuit, and thus can be bonded together. There is no need to bond the two layers of flexible circuits with an adhesive.
[0056] In one embodiment, the flexible substrate is a polydimethylsiloxane flexible substrate, which is made by mixing polydimethylsiloxane and a curing agent and drying them to have viscosity, wherein the mass fraction of polydimethylsiloxane is 80%-90% and the mass fraction of the curing agent is 20%-10%.
[0057] In other embodiments, the flexible substrate of the first layer of flexible circuit and the flexible substrate of the second layer of flexible circuit may also be bonded by an adhesive.
[0058] In one embodiment, the material of the liquid metal in the liquid metal conductive layer is gallium, gallium-indium alloy or gallium-indium-tin alloy.
[0059] In one embodiment, the material of the liquid metal in the liquid metal droplets 1 - 3 is gallium, gallium-indium alloy or gallium-indium-tin alloy.
[0060] In one embodiment, in the gallium-indium alloy, the mass ratio of gallium to indium is 90.0:10.0 - 75.5:24.5, preferably, the mass ratio of gallium to indium is 75.5:24.5.
[0061] In one embodiment, the thickness of the flexible substrate is 0.3 mm to 0.4 mm.
[0062] In one embodiment, the material used for the flexible cover 1-4 is the same as that used for the flexible substrate. For example, the flexible cover 1-4 is also adhesive, so that it can more reliably cover the surface of the liquid metal conductive layer 1-2 of the first layer of the flexible circuit and block the opening of the through hole.
[0063] An embodiment of the present application further provides a multi-layer conductive interconnection method based on liquid metal and flexible circuit, which is used to form a multi-layer conductive interconnection structure based on liquid metal and flexible circuit according to any of the above embodiments. The method includes the following steps when connecting two adjacent layers of flexible circuits:
[0064] S100: Open a through hole on the first layer of flexible circuit.
[0065] S200: Covering the flexible substrate 1-1 of the first layer of flexible circuit on the side of the second layer of flexible circuit provided with the liquid metal conductive layer 2-2.
[0066] S300: pouring liquid metal droplets 1-3 into the through hole.
[0067] S400: a flexible cover 1-4 is provided on the surface of the liquid metal conductive layer 1-2 of the first layer of the flexible circuit to seal the opening of the through hole.
[0068] When connecting two adjacent layers of flexible circuits, the multi-layer conductive interconnection method based on liquid metal and flexible circuits first opens a through hole on the first layer of flexible circuit, then covers the side of the second layer of flexible circuit provided with the liquid metal conductive layer 2-2 with the flexible substrate 1-1 of the first layer of flexible circuit, then pours liquid metal droplets 1-3 into the through hole, and finally sets a flexible cover 1-4 on the surface of the liquid metal conductive layer 1-2 of the first layer of flexible circuit to block the opening of the through hole. In this way, the liquid metal conductive layer 1-2 of the first layer of flexible circuit and the liquid metal conductive layer 2-2 of the second layer of flexible circuit can be conductively connected through the liquid metal droplets 1-3. The flexible cover 1-4 is set on the surface of the liquid metal conductive layer 1-2 of the first layer of flexible circuit and blocks the opening of the through hole, so that the liquid metal droplets 1-3 can be sealed in the through hole to prevent leakage. Since the flexible substrate has certain stretchability and flexibility, and the liquid metal has high electrical conductivity and good conductive stability, the tensile deformation has almost no effect on its resistance. Therefore, the structure prepared by the above-mentioned multi-layer conductive interconnection method based on liquid metal and flexible circuit can form a stable conductive interconnection while having certain flexibility and stretchability.
[0069] In one embodiment, laser cutting is used to open through holes on the first layer of flexible circuit. Laser cutting has high hole opening accuracy, can ensure the quality of the opening as much as possible and prevent damage to the first layer of flexible circuit.
[0070] In one embodiment, the through hole is a circular hole. When the thickness of the flexible substrate 1-1 of the first layer of the flexible circuit is 0.3 mm to 0.4 mm, and the flexible substrate 1-2 is a polydimethylsiloxane flexible substrate, a carbon dioxide laser cutting machine is used to cut two circular holes with a diameter of 1 mm, wherein the laser power is 70%, the speed is 60%, the PPI (Pixels Per Inch) is 50%, and the Z-axis cutting depth is set to 0.1 mm.
[0071] According to the applicant's test, when the thickness of the flexible substrate 1-1 of the first layer of flexible circuit is 0.3mm~0.4mm, and the flexible substrate 1-2 is a polydimethylsiloxane flexible substrate, when the parameters of the carbon dioxide laser cutting machine are set to the above data, the quality of the above two circular holes cut out is excellent and damage to the flexible substrate 1-1 can be prevented.
[0072] like Figure 5 and Figure 6 As shown, in one embodiment, the second layer of flexible circuits may include two flexible circuits. When the first layer of flexible circuits is provided with two through holes, liquid metal droplets 1-3 are respectively provided in the two through holes, so that the first layer of flexible circuits can be electrically connected to the second layer of flexible circuits through the liquid metal droplets 1-3 in the two through holes.
[0073] In one embodiment, the liquid metal droplets 1-3 are poured into the through hole by a needle syringe, which is convenient for operation and the liquid metal droplets 1-3 are not easy to leak.
[0074] In one embodiment, the step of providing a flexible cover 1-4 on the surface of the liquid metal conductive layer 1-2 of the first layer of the flexible circuit is as follows: covering the position where the through hole is provided on the surface of the liquid metal conductive layer 1-2 of the first layer of the flexible circuit with a mixed solution of polydimethylsiloxane and a curing agent and drying it to form a flexible cover 1-4.
[0075] Polydimethylsiloxane and a curing agent are mixed to form a mixed solution, and the mixed solution is covered on the surface of the liquid metal conductive layer 1-2 of the first layer of the flexible circuit at the position where the through hole is provided, and after drying, a flexible cover 1-4 can be formed. The mass fraction of polydimethylsiloxane is 80%-90%, and the mass fraction of the curing agent is 20%-10%.
[0076] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0077] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.
Claims
1. A multi-layer conductive interconnect structure based on liquid metal and flexible circuit, characterized in that: The invention comprises at least two layers of flexible circuits stacked together, wherein the flexible circuit comprises a flexible substrate and a liquid metal conductive layer arranged on the surface of the flexible substrate; In two adjacent layers of the flexible circuits, the flexible substrate of the first layer of the flexible circuit covers the side of the second layer of the flexible circuit where the liquid metal conductive layer is provided; The first layer of the flexible circuit is provided with a through hole, the through hole penetrates the flexible substrate and the liquid metal conductive layer of the first layer of the flexible circuit, and a liquid metal droplet is arranged in the through hole; the first layer of the flexible circuit also includes a flexible cover, the flexible cover is arranged on the surface of the liquid metal conductive layer and blocks the opening of the through hole; The liquid metal conductive layer of the first layer of the flexible circuit and the liquid metal conductive layer of the second layer of the flexible circuit are conductively connected via the liquid metal droplets.
2. The multi-layer conductive interconnect structure based on liquid metal and flexible circuit according to claim 1, characterized in that: The flexible substrate is an adhesive substrate, so that the flexible substrate of the first layer of the flexible circuit is bonded with the flexible substrate of the second layer of the flexible circuit.
3. The multi-layer conductive interconnect structure based on liquid metal and flexible circuit according to claim 2, characterized in that: The flexible substrate is a polydimethylsiloxane flexible substrate.
4. The multi-layer conductive interconnect structure based on liquid metal and flexible circuit according to claim 1, characterized in that: The flexible substrate of the first layer of the flexible circuit and the flexible substrate of the second layer of the flexible circuit are bonded together by an adhesive.
5. The multi-layer conductive interconnect structure based on liquid metal and flexible circuit according to claim 1, characterized in that: The through hole is filled with the liquid metal droplets.
6. The multi-layer conductive interconnect structure based on liquid metal and flexible circuit according to claim 1, characterized in that: The thickness of the flexible substrate is 0.3 mm to 0.4 mm.
7. The multi-layer conductive interconnect structure based on liquid metal and flexible circuit according to claim 1, characterized in that: The material used for the flexible cover is the same as the material used for the flexible substrate.