Stretchable circuit and preparation method thereof, flexible electronic integrated system

Abstract

The present application relates to the field of flexible electronic integration technology, and in particular to stretchable circuits and preparation methods thereof, and flexible electronic integration systems. The stretchable circuit includes a stretchable substrate, a stretchable conductive pattern is encapsulated inside the stretchable substrate, and a plurality of through holes are opened in the stretchable substrate; at least part of the through holes extend from the outer surface of the stretchable substrate to the stretchable conductive pattern, and a stretchable conductor is filled in the through hole, one end of the stretchable conductor is connected to the stretchable conductive pattern, and the other end extends to the outer surface of the stretchable substrate. The stretchable conductor and the stretchable conductive pattern form a three-dimensional conductive path, so that the electronic components can realize electrical signal conduction from the outside to the inside of the stretchable substrate. Connection with hard electronic components can maintain good mechanical stability and electrical stability, and mechanical failure and electrical failure are not prone to occur. In addition, the electronic components can be removed and replaced with the required new electronic components, which is convenient and quick, and improves functionality and adaptability.

Description

Technical Field

[0001] The present application relates to the field of flexible electronic integration technology, and in particular to stretchable circuits and preparation methods thereof, and flexible electronic integration systems. Background Art

[0002] Flexible electronic integrated systems are integrated systems that integrate a series of electronic components on a flexible substrate and enable the electronic components to work together, such as flexible LED integrated devices, flexible chip integrated devices, flexible sensor integrated devices, flexible ultrasonic integrated devices, etc. Flexible electronic integrated systems often deform during use, and require various components (such as chips, capacitors, resistors, etc.) to remain interconnected and work normally. Therefore, components often need to be connected through stretchable circuits. The connection between the stretchable circuit and the circuit pins of the components is called an interface. The interface also needs to ensure performance as it deforms, so there are high requirements for the electrical and mechanical stability of the interface.

[0003] There are two methods for processing existing stretchable circuits and interfaces: the first is to make the copper foil into a winding shape, or to design a microstructure, and the interface is soldered with solder such as tin wire, silver-tin alloy, etc. to improve the electrical and mechanical stability of the interface, but the soldering temperature of the solder often exceeds 150°C or even reaches 400°C, which is easy to damage the flexible substrate or components; in addition, the flexibility of the solder is often not as good as the flexible substrate, that is, the modulus is higher than the flexible substrate, resulting in modulus mismatch, and the interface is prone to failure with tensile deformation during long-term use; moreover, it is extremely inconvenient to replace components after welding, which limits the function. The second is to use commercial silver paste at the interface. The temperature is not high and will not damage the flexible substrate or components, but the interface made of silver paste will become hard and the interface is almost impossible to stretch. Usually, electrical failure will occur at 50% deformation and mechanical failure will occur at 100% deformation. Summary of the invention

[0004] The purpose of this application is to provide a stretchable circuit and a preparation method thereof, and a flexible electronic integrated system, aiming to solve the problem of low electrical stability and mechanical stability of the interface of the stretchable circuit in the prior art.

[0005] In order to achieve the above application purpose, the technical solution adopted in this application is as follows:

[0006] In a first aspect, the present application provides a stretchable circuit, comprising a stretchable substrate, wherein a stretchable conductive pattern is encapsulated inside the stretchable substrate, and the stretchable substrate is provided with a plurality of through holes; at least some of the through holes extend from the outer surface of the stretchable substrate to the stretchable conductive pattern, and a stretchable conductor is filled in the through holes, one end of the stretchable conductor is connected to the stretchable conductive pattern, and the other end extends to the outer surface of the stretchable substrate.

[0007] The stretchable substrate, stretchable conductive pattern, and stretchable conductor in the stretchable circuit of the present application are all stretchable, giving the stretchable circuit a stretchable performance. The end of the stretchable conductor extending to the outer surface of the stretchable substrate can be used to be electrically connected to the circuit pin of the electronic component, and the electronic component is connected to the stretchable circuit. Since the through hole and the stretchable conductor connect the inside and outside of the stretchable substrate, the stretchable conductor and the stretchable conductive pattern form a three-dimensional conductive path, so that the electronic component can realize electrical signal conduction from the outside to the inside of the stretchable substrate. Since the through hole is filled with a stretchable conductor, even under the conditions of complex external stress, tensile deformation, long-term use, etc., it can maintain good mechanical stability and electrical stability when connected to hard electronic components, and it is not easy to have mechanical failure and electrical failure, and can be used for flexible electronic integrated systems. And according to the use scenario requirements, the electronic components can be removed from the stretchable circuit and replaced with the required new electronic components, which is convenient and quick, and improves functionality and adaptability.

[0008] In a second aspect, the present application provides a method for preparing the stretch circuit of the above-mentioned application, comprising the following steps:

[0009] encapsulating the stretchable conductive pattern inside the stretchable substrate;

[0010] Punching the stretchable substrate to form a plurality of through holes;

[0011] The raw material of the stretchable conductor is molded at the position of the through hole to form the stretchable conductor.

[0012] The preparation method of the present application obtains the stretchable circuit of the above application by the steps of first encapsulating, then punching and finally forming a stretchable conductor, which has stretchable properties, and the stretchable conductor and the stretchable conductive pattern form a three-dimensional conductive path, so that the electronic components can conduct electrical signals from the outside of the stretchable substrate to the inside thereof. The above preparation method is process controllable, and the obtained stretchable circuit can maintain good mechanical stability and electrical stability under complex external stress, is not prone to mechanical failure and electrical failure, and can be used in flexible electronic integrated systems.

[0013] In a third aspect, the present application provides a flexible electronic integrated system, including electronic components, and also including a stretchable circuit of the above-mentioned application or a stretchable circuit prepared by the preparation method of the above-mentioned application, wherein the circuit pins of the electronic components are connected to the stretchable conductor of the stretchable circuit.

[0014] The flexible electronic integrated system of the present application connects electronic components to a stretchable circuit, and the circuit pins are connected to a stretchable conductor, so that the electronic components are electrically connected to the stretchable conductive pattern, thereby integrating the electronic components to form a flexible electronic integrated system. The stretchable circuit can be stretched, and the connection with the rigid electronic components can also maintain good mechanical stability and electrical stability, and is not prone to mechanical failure and electrical failure, and can work stably for a long time under the action of complex external stress. The electronic components can include LEDs, chips, sensors, ultrasonic devices, etc., and then obtain a corresponding flexible electronic integrated system, and according to the use scenario requirements, the electronic components can be removed and replaced with the required new electronic components, which is convenient and fast, and improves functionality and adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 is a schematic diagram of the structure of the stretchable circuit of the present application;

[0017] Figure 2 is a schematic diagram of the overall structure of the stretchable circuit of Example 1;

[0018] Figure 3 is a schematic diagram of the structure and conductive path of the through-hole region of the stretchable circuit in Example 1;

[0019] Figure 4 is a SEM image of a non-through-hole region of the stretchable circuit of Example 1;

[0020] Figure 5 is a SEM image of the through-hole region of the stretchable circuit of Example 1;

[0021] Figure 6 This is a graph showing the electrical stability of the stretchable circuit of Example 1 after 10,000 stretching cycles;

[0022] Figure 7 This is a graph showing the electrical stability of the stretchable circuit of Example 1 after 5000 stretching cycles;

[0023] Figure 8 This is a test diagram of the resistance change value and resistance change rate of the stretchable circuit of Example 1 as the stretching deformation rate changes;

[0024] Fig. 9100 times of stretching cycles of the stretchable circuit of Example 1 under different stretching deformations, and 100 times of stretching cycles of the stretchable circuit of Comparative Example 3;

[0025] Fig.10 The test diagrams of shear strength and interface toughness of the stretchable circuits of Example 1 and Comparative Example 3 respectively installed with LED lamps;

[0026] Fig.11 This is a comparison chart of the electrical stretch rate and mechanical stretch rate of Example 3 and other stretchable circuit-mounted LED lamps in the prior art.

[0027] Reference numerals:

[0028] 1-stretchable substrate; 11-through hole;

[0029] 2-Stretchable conductive patterns;

[0030] 3-Stretchable conductors. DETAILED DESCRIPTION

[0031] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0032] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0033] In this application, "at least one" means one or more, "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items.

[0034] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0035] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also indicate the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass in the embodiment description of the present application can be a mass unit known in the chemical industry such as µg, mg, g, kg, etc.

[0036] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0037] Mechanical failure in this application refers to mechanical failure after deformation, inability to stretch further, or inability to return to its original shape, or the occurrence of tearing, breaking, etc.

[0038] Electrical failure in this application refers to a significant decrease in electrical performance after deformation, such as a significant decrease in conductivity, or unstable conductivity.

[0039] The mechanical stability, mechanical elongation, electrical stability, and electrical elongation in this application refer to the degree of change in mechanical strength and electrical properties after tensile deformation.

[0040] A first aspect of the present application provides a stretchable circuit, as an embodiment of the present application, Figure 1 As shown, the stretchable circuit includes a stretchable substrate 1, a stretchable conductive pattern 2 is encapsulated inside the stretchable substrate 1, and a plurality of through holes 11 are opened in the stretchable substrate 1; at least part of the through holes 11 extend from the outer surface of the stretchable substrate 1 to the stretchable conductive pattern 2, and a stretchable conductor 3 is filled in the through hole 11, one end of the stretchable conductor 3 is connected to the stretchable conductive pattern 2, and the other end extends to the outer surface of the stretchable substrate 1.

[0041] The stretchable substrate, stretchable conductive pattern, and stretchable conductor in the stretchable circuit of the embodiment of the present application are all stretchable, giving the stretchable circuit a stretchable property. The end of the stretchable conductor extending to the outer surface of the stretchable substrate can be used to be electrically connected to the circuit pin of the electronic component, and the electronic component is connected to the stretchable circuit. Since the through hole and the stretchable conductor connect the inside and outside of the stretchable substrate, the stretchable conductor and the stretchable conductive pattern form a three-dimensional conductive path, so that the electronic component can achieve electrical signal conduction from the outside to the inside of the stretchable substrate. Since the through hole is filled with a stretchable conductor, even under the conditions of complex external stress, tensile deformation, long-term use, etc., it can maintain good mechanical stability and electrical stability when connected to a hard electronic component, and it is not easy to have mechanical failure and electrical failure, and can be used for a flexible electronic integrated system. And according to the use scenario requirements, the electronic component can be removed from the stretchable circuit and replaced with the required new electronic component, which is convenient and fast, and improves functionality and adaptability.

[0042] The following describes the various parts of the stretchable circuit in the embodiment of the present application:

[0043] About Stretchable Conductive Patterns:

[0044] The stretchable conductive pattern plays a role similar to that of a wire, and can be stretched as the stretchable substrate is stretched, and still has conductivity during the stretching process. In some embodiments, the stretchable pattern can be made of copper foil into a meandering shape, or a microstructure design can be performed, and a stretchable composite material can be made of silver powder, liquid metal, polymer conductive liquid, etc. In some embodiments, the material of the stretchable conductive pattern includes at least one of liquid metal, nanomaterial-modified liquid metal, and liquid conductive organic matter (such as conductive polymer PEDOT:PSS, etc.), and nano-modified liquid metal is optional. The liquid metal can be at least one of gallium-indium alloy and pure gallium. In the exemplary embodiment, the mass ratio of gallium to indium in the gallium-indium alloy can be (2-5):1, and can be 3:1. Nano-modification can be modified by mixing nanomaterials with the above-mentioned liquid metal. After modification, the viscosity can be increased, the surface tension can be increased, and it is more conducive to the formation of the stretchable conductive pattern. The nanomaterial can be nanoclay, copper nanoparticles, nickel nanoparticles, etc., and the mass ratio of gallium-indium alloy to nanoclay can be (4-19):1. The above materials give the stretchable conductive pattern good conductivity and stretchability. In general, after the conductive material is stretched and deformed, the resistance tends to increase as the length increases. Many conductive materials are very sensitive to deformation, and a small amount of stretching deformation will cause the resistance to increase rapidly. The stretchable conductive pattern using the above materials can maintain the stability of the conductive performance during the stretching process, and the conductivity will not change significantly due to stretching deformation. Among them, the conductivity of liquid metal can reach 1~8×10 6S / m, rheological properties can reach 2~4×10 -3 Pa.s.

[0045] The stretchable conductive pattern can be in a variety of shapes, including linear and strip shapes. In the exemplary embodiment, the stretchable conductive pattern can be in a strip shape, consisting of two or more stretchable conductive units, each of which can be connected to a number of stretchable conductors, which are connected to the circuit pins of the electronic components, so that a number of electronic components can be connected in series or in parallel. The positional relationship between each stretchable conductive unit can be parallel, cross, end point connection, etc. to form a stretchable conductive pattern, and further integrate a number of electronic components on the entire stretchable circuit.

[0046] In some embodiments, the thickness of the stretchable conductive pattern can be 1 to 20 μm; in the exemplary embodiment, it can include but is not limited to any value of 1 μm, 5 μm, 10 μm, 20 μm or a range between any two values, so that the stretchable conductive pattern can take into account properties such as conductivity, stretchability, mechanical stability, and electrical stability.

[0047] About the stretchable matrix:

[0048] The stretchable substrate is the substrate of the entire stretchable circuit. Due to its stretchable properties, it can adapt to complex flexible stretching usage scenarios and can also protect the stretchable conductive pattern encapsulated inside. In some embodiments, the thickness of the stretchable substrate is 150 to 300 μm; in the exemplary embodiment, it may include but is not limited to any value of 150 μm, 200 μm, 260 μm, 300 μm or a range between any two values. The stretchable substrates of these thicknesses are conducive to taking into account the stretchability, flexibility, and protection of the stretchable conductive pattern.

[0049] In some embodiments, the material of the stretchable matrix includes at least one of SEBS, PDMS, and ECOFLEX, and SEBS can be selected. SEBS is a linear triblock copolymer with polystyrene as the terminal segment and ethylene-butylene copolymer obtained by hydrogenation of polybutadiene as the middle elastic block. PDMS is polydimethylsiloxane, and ECOFLEX is BASF's compostable plastic. These materials give the stretchable matrix the following beneficial effects: it has good stretchability and can still maintain mechanical stability under large deformation; these materials are insulating materials and will not affect the transmission of electrical signals; they also have high interfacial adhesion energy, which is not only conducive to improving the bonding strength with the stretchable conductor, improving the mechanical stability and electrical stability of the stretchable circuit, but also conducive to improving the bonding strength with hard electronic components, and the electronic components can be adhered to the stretchable circuit, and the bonding strength with the skin, robot arms, etc. in the use scenario can be improved, and it is not easy to fall off even under complex stress.

[0050] Regarding the through holes on the stretchable substrate:

[0051] At least some of the through holes connect the outer surface of the stretchable substrate and the stretchable conductive pattern, and can form a three-dimensional conductive path that is electrically connected inside and outside with the stretchable conductor filled therein. The positions of these through holes can also serve as interface positions for connecting with electronic components. The shapes of the through holes can include regular shapes such as cylindrical, prismatic, and terraced, and can also include other irregular shapes.

[0052] In some embodiments, the aperture of the through hole can be 1 to 50 μm; in the exemplary embodiment, it can include but is not limited to any value of 1 μm, 10 μm, 30 μm, 50 μm or a range between any two values. The depth of the through hole can be 10 to 30 μm; in the exemplary embodiment, it can include but is not limited to any value of 10 μm, 15 μm, 20 μm, 25 μm, 30 μm or a range between any two values. When the material of the stretchable conductive pattern is liquid metal or nanomaterial-modified liquid metal, there is a risk of outflow leakage. These micron-sized through holes and depth are conducive to reducing the occurrence of outflow.

[0053] In some embodiments, the number of through holes is ≥ 2, and each through hole is arranged at intervals, so that multiple electronic components can be connected to the stretchable circuit, thereby improving the functionality of the flexible electronic integrated system. In some embodiments, the through holes can be randomly distributed, or regularly distributed according to a certain distribution density according to the design requirements of the electronic integrated system, so that a reasonable distribution distance is maintained between the stretchable conductors and between the electronic components, so that the electronic components can ensure smooth transmission of electrical signals and reduce mutual interference in electromagnetic and heat dissipation aspects.

[0054] About stretchable conductors:

[0055] Compared with the prior art using welding, commercial silver paste and other methods, the stretchable conductor is selected in the stretchable circuit of the embodiment of the present application. On the one hand, the stretchable conductor itself has stretchable properties and can be stretched together with the stretchable substrate. During the stretching deformation process, its own mechanical properties are stable and not easy to break, and its conductive performance is stable; on the other hand, the stretchable conductor is connected to the stretchable conductive pattern, which is conducive to stable connection and not easy to disconnect and cause circuit failure after being subjected to complex external stress, especially stretching deformation; on the other hand, the stretchable conductor is conducive to firm bonding with the surface of the material of the stretchable substrate, the inner wall of the through hole, etc., and is not easy to fall off during stretching deformation; on the other hand, when the material of the stretchable conductive pattern contains liquid conductive material, the stretchable conductor is also conducive to preventing liquid metal leakage.

[0056] In some embodiments, the material of the stretchable conductor includes at least one of deposited gold, deposited silver, deposited chromium, and deposited copper, and these deposited materials are all nanoparticles, which can be deposited gold or deposited gold nanoparticles. These materials give the stretchable conductor excellent stretchability, and the electrical properties are stable during the stretching deformation process, the conductive properties will not decrease significantly, and mechanical failure and electrical failure are not easy to occur. In addition, when the nano-deposition materials such as deposited gold nanoparticles are selected, and the material of the stretchable matrix is ​​the above-mentioned SEBS and other materials, the bonding surface of the stretchable conductor and the stretchable substrate forms a stable two-phase interface, called BIND (biphasic nano-dispersed) interface, that is, a two-phase nano-dispersed interface. This BIND interface is conducive to improving the bonding strength between the stretchable conductor and the stretchable matrix, and improving the conductivity of the interface. In addition, when the deposition materials such as deposited gold nanoparticles are selected, the material of the stretchable conductive pattern can be selected from liquid metal, nanomaterial-modified liquid metal, liquid conductive organic matter, etc. At this time, a solid-liquid metal film is formed at the connection between the stretchable conductor and the stretchable conductive pattern, that is, a solid-liquid conductive interface. Therefore, there are both BIND interfaces and solid-liquid conductive interfaces in the through hole. The stretchable conductor, stretchable conductive pattern, and stretchable matrix together form a hybrid biphasic interface (HBI interface), which is a three-dimensional composite conductive interface. Such an HBI interface is conducive to improving the stability of the mutual bonding, improving the conductivity of the area, and improving the mechanical and electrical performance stability when tensile deformation occurs. It is not easy to cause mechanical or electrical failure, and the resistance will not increase rapidly.

[0057] In addition, the electronic components can also be modified to form a BIND interface. Specifically, at least one of SEBS, PDMS, and ECOFLEX can be adhered to one surface of the electronic component, and then at least one of gold, silver, chromium, and copper can be deposited on the surface. The modified side is then pressed and combined with the interface of the stretchable circuit to connect the stretchable circuit. The HBI interface in the stretchable circuit and the BIND interface of the modified electronic component work together to form an HBI-BIND interface. While ensuring the mechanical stability of the stretchable circuit and the electronic component, the electrical stability is further improved. The electronic component can be stretched to a larger deformation while maintaining a stable resistance value, thereby ensuring stable transmission of electrical signals between the electronic component and the stretchable circuit.

[0058] In some embodiments, the shape of the stretchable conductor can be a shape that completely fills the corresponding through hole. This shape of the stretchable conductor completely filling the through hole is conducive to improving the bonding strength between the two and improving the mechanical and electrical stability of the stretchable conductor. The end of the stretchable conductor extending to the outer surface of the stretchable substrate can serve as an interface for connecting to the circuit pin of the electronic component.

[0059] In some embodiments, the end of the stretchable conductor extending to the outer surface of the stretchable substrate is film-shaped and adheres to the outer surface of the stretchable substrate. This extended end can serve as an interface for connecting with the circuit pin of the electronic component; the end being film-shaped and adhering to the stretchable substrate is conducive to the formation of a BIND interface between the two, thereby improving the bonding strength and improving the mechanical stability and electrical stability during tensile deformation.

[0060] In some embodiments, the stretchable conductor can be formed into a cylindrical film and adhered to the inner wall of the through hole, and at least close one end of the through hole close to the stretchable conductive pattern to prevent the stretchable conductive pattern from being exposed. This shape is also conducive to the formation of a BIND interface between the stretchable conductor and the inner wall of the through hole, thereby improving the bonding strength of the stretchable conductor filled in the through hole, and improving the mechanical and electrical stability of the stretchable conductor. The holes in the cylindrical stretchable conductor can be used as an interface for connecting to the circuit pins of electronic components.

[0061] In summary, the mechanical stability and electrical stability of the stretchable circuit of the embodiment of the present application are high, and mechanical failure and electrical failure are not easy to occur after stretching deformation. In the embodiment, the resistance value of the stretchable circuit is ≤0.2 Ω, and the conductivity is good. During the stretching cycle of the stretchable circuit within 10,000 times, even if 50% stretching deformation occurs in each stretching cycle, the resistance change rate of the entire stretchable circuit can still be ≤2.5%, indicating that the stretchable circuit not only has stable resistance after stretching deformation, but also can withstand tens of thousands of stretching cycles, indicating that it has good electrical stability. Moreover, the stretching deformation can even reach 800%, and its resistance value change rate is still ≤6%. It can be seen that the stretching limit of the stretchable circuit is very high. Even with such a large stretching deformation, its resistance value changes are still very small, indicating good electrical stability. Therefore, the stretchable circuit of the embodiment of the present application is deformation insensitive, that is, after stretching deformation, its mechanical properties and electrical properties have a low change rate and good stability.

[0062] A second aspect of the present application provides a method for preparing a stretch circuit according to the above application embodiment, comprising the following steps:

[0063] S10: encapsulating the stretchable conductive pattern inside the stretchable substrate;

[0064] S20: punching the stretchable substrate to form a plurality of through holes;

[0065] S30: forming the raw material of the stretchable conductor at the position of the through hole to form the stretchable conductor.

[0066] The preparation method of the embodiment of the present application obtains the stretchable circuit of the embodiment of the present application by the steps of first encapsulating, then punching and finally forming a stretchable conductor, which has a stretchable property, and the stretchable conductor and the stretchable conductive pattern therein form a three-dimensional conductive path, so that the electronic components can conduct electrical signals from the outside of the stretchable substrate to the inside thereof. The above preparation method is process controllable, and the obtained stretchable circuit can maintain good mechanical stability and electrical stability under complex external stress, is not prone to mechanical failure and electrical failure, and can be used in flexible electronic integrated systems.

[0067] Step S10: is a step of encapsulating the stretchable conductive pattern. In the exemplary embodiment, a channel can be opened in the stretchable substrate, and the formed stretchable conductive pattern can be introduced into the channel, and finally encapsulated. The stretchable substrate can also be divided into a base layer and an encapsulation layer, and a stretchable conductive pattern is formed on the base layer, and finally an encapsulation layer is formed for encapsulation. When the latter method is adopted, the material of the stretchable substrate needs to have strong self-adhesion properties so that the base layer and the encapsulation layer can self-adhere to form a stretchable substrate as a whole. In the exemplary embodiment, the material of the stretchable substrate can include at least one of the above-mentioned SEBS, PDMS, and ECOFLEX.

[0068] The material of the stretchable conductive pattern may include at least one of the above-mentioned liquid metal, nanomaterial-modified liquid metal, and conductive organic matter (such as conductive polymer PEDOT:PSS). In the exemplary embodiment, the nanomaterial in the nanomaterial-modified liquid metal includes at least one of nanoclay, copper nanoparticles, and nickel nanoparticles. The liquid metal includes at least one of gallium-indium alloy and pure gallium. In the exemplary embodiment, it includes nanoclay-modified gallium-indium alloy. The preparation method includes adding nanoclay to the gallium-indium alloy and mixing them thoroughly. The mass ratio of gallium to indium in the gallium-indium alloy can be (2-5):1, and in the exemplary embodiment, it is 3:1. The mass ratio of gallium-indium alloy to nanoclay can be (4-19):1, and in the exemplary embodiment, it can include but is not limited to any ratio of 4:1, 9:1, 14:1, and 19:1 or the range between any two ratios. That is, the gallium-indium alloy can account for 80% to 95% of the total mass of the gallium-indium alloy and nanoclay. Nanomodification is beneficial to increase viscosity and surface tension, which is beneficial to the formation of stretchable conductive patterns. During the mixing process, the nanoclay and gallium-indium alloy will gradually change from the initial obvious stratification state to gray, and finally show a metallic color, indicating that the modification of the nanomaterial is completed.

[0069] After the material of the stretchable conductive pattern is prepared, a patterned template can be provided to form the stretchable conductive pattern. Polyethylene terephthalate (PET) material can be selected for laser cutting as a patterned template, a glass sheet can be used as a scraper, and the base layer of the raw materials such as SEBS mentioned above is used as a base. The material of the stretchable conductive pattern is scraped on the base through the patterned template, and the stretchable conductive pattern is obtained after molding. Finally, encapsulation is performed. In the demonstration example, the stretchable conductive pattern can be encapsulated by spin coating the raw materials such as SEBS to obtain an encapsulation layer. Thereby, the base layer and the encapsulation layer form an integrated stretchable matrix, and the stretchable conductive pattern is encapsulated therein.

[0070] Step S20 is a step of forming a through hole, and the through hole is obtained by punching. The shape, diameter, depth and other parameters of the through hole can be seen in the above content. In some embodiments, the punching process includes laser etching. In an exemplary embodiment, a CO2 laser can be used to perform etching to form a through hole on the stretchable substrate.

[0071] Step S30 is a step of preparing a stretchable conductor, so that the stretchable conductor and the stretchable conductive pattern form a three-dimensional conductive path, so that the electronic components can realize electrical signal conduction from the outside to the inside of the stretchable substrate. In some embodiments, the molding method includes at least one of evaporation, sputtering, and deposition. The optional evaporation method uses a mask plate to cover the outer surface of the stretchable substrate and evaporate the raw material of the stretchable conductor to the area where the through hole is located. The material of the stretchable conductor may include at least one of deposited gold, deposited silver, deposited chromium, and deposited copper. On the one hand, these methods can form a stretchable conductor filled in the through hole, and the formed stretchable conductor has good stretchability, high mechanical stability and electrical stability during the stretching deformation process, and is not prone to mechanical failure or electrical failure; on the other hand, one end of the stretchable conductor will also be connected to the stretchable conductive pattern at the bottom of the through hole to form a solid-liquid conductive interface, and form a BIND interface with the stretchable matrix, which is conducive to the formation of an HBI interface in the through hole, improves the stability of the combination between the three, improves the conductivity of the area, and the mechanical and electrical properties during stretching deformation are stable; on the other hand, the stretchable conductor is firmly bonded to the inner wall of the through hole, and the other end of the stretchable conductor can extend to the outer surface of the stretchable matrix, and the bonding with the surface of the stretchable matrix is ​​also more stable.

[0072] After the stretchable conductor is prepared, the stretchable circuit of the above-mentioned application embodiment is obtained, and the area where the through hole is located and the end of the stretchable conductor extending to the outer surface of the stretchable substrate can be used as an interface connected to the circuit pin of the electronic component. The stretchable circuit can be stretched, and it is not easy to fail mechanically and electrically after stretching and deformation. It can form a flexible electronic integrated system with electronic components, and the electronic components can be replaced.

[0073] A third aspect of an embodiment of the present application provides a flexible electronic integrated system, including an electronic component, and also including a stretchable circuit according to the above embodiment of the application or a stretchable circuit prepared by the preparation method of the above embodiment of the application, wherein the circuit pins of the electronic component are connected to the stretchable conductor of the stretchable circuit.

[0074] The flexible electronic integrated system of the embodiment of the present application connects electronic components to a stretchable circuit, and the circuit pins are connected to a stretchable conductor, so that the electronic components are electrically connected to the stretchable conductive pattern, thereby integrating the electronic components to form a flexible electronic integrated system. The stretchable circuit can be stretched, and the connection with the rigid electronic components can also maintain good mechanical stability and electrical stability, and is not prone to mechanical failure and electrical failure, and can work stably for a long time under the action of complex external stress. The electronic components may include LEDs, chips, sensors, ultrasonic devices, etc., and then a corresponding flexible electronic integrated system is obtained.

[0075] In addition, the substrate of the stretchable circuit can be made of an adhesive material to which electronic components can be attached. The electronic components can be easily connected by directly aligning them with the interface of the stretchable circuit and pressing them. According to the requirements of the use scenario, the electronic components can be removed and replaced with the required new electronic components without affecting the interface. They can be installed and removed multiple times, which is convenient and fast, and improves functionality and adaptability.

[0076] The following describes the invention in conjunction with specific embodiments.

[0077] Example 1

[0078] This embodiment provides a stretchable circuit and a method for preparing the same. Figure 2 , Figure 3 The schematic diagram drawn shows that the stretchable circuit includes a stretchable substrate, the material is SEBS, and the thickness is about 260 μm; a stretchable conductive pattern is encapsulated therein, including 6 parallel strip patterns, the material is nanoclay modified gallium indium alloy. Through holes are opened on the stretchable substrate, one end of each through hole is connected to the stretchable conductive pattern, and the other end extends to the outer surface of the stretchable substrate. There are 3 through holes on each strip pattern, the apertures of these through holes range from 10 μm to 40 μm, most of which are about 25 μm, and the depths range from 10 μm to 20 μm, most of which are about 15 μm. A stretchable conductor is embedded in the through hole, and the material is deposited gold. One end of the stretchable conductor forms a conductive interface of a solid-liquid metal film with the nanoclay modified gallium indium alloy at the bottom of the through hole, and the deposited gold also forms a BIND with SEBS. Therefore, the stretchable conductive pattern, the stretchable conductor, and the stretchable substrate form an HBI interface in the through hole. The other end of the stretchable conductor extends to the outer surface of the stretchable substrate and can serve as an interface for the circuit pins of the electronic component.

[0079] The stretchable conductive pattern and the stretchable conductor form a three-dimensional conductive path, and the inside and outside of the stretchable circuit are electrically connected, and electrons can migrate along the conductive path. Since the stretchable conductive pattern of the stretchable circuit of this embodiment is connected to multiple interfaces, multiple electronic components can be integrated on the stretchable conductive pattern to obtain a flexible electronic integrated system, wherein the electronic components can be adhered to the outer surface of the stretchable substrate in the area where the through holes are located, and the interfaces of the electronic components such as pins can be electrically connected to the interfaces of the stretchable circuit. In addition, the adhered electronic components can be removed and new electronic components can be adhered to the corresponding positions. This process will not damage the interface of the stretchable circuit, so that another flexible electronic integrated system can be obtained by replacing the electronic components.

[0080] The method for preparing a stretchable circuit comprises the following steps S1 to S4;

[0081] S1. Prepare raw materials:

[0082] Toluene solvent was used to dissolve SEBS1221 to prepare a 15 wt% concentration SEBS solution as a raw material for the stretchable matrix.

[0083] Weigh 300 g of gallium and 100 g of indium accurately, place them together in a clean glass bottle, and then put them in a vacuum drying oven, set the temperature to 200°C, and let them stand for 48 hours in this environment to ensure that gallium and indium can completely fuse to form a gallium-indium alloy, then take them out and store them properly for later use. Use a syringe to take out an appropriate amount of the prepared gallium-indium alloy and put it in a beaker. We add nanoclay to the beaker in a certain proportion, with a mass ratio of gallium-indium alloy: nanoclay of 9:1, and use a blender to stir them thoroughly. During the stirring process, it can be observed that the material in the beaker gradually changes from the initial obvious stratification state to gray, and finally shows a metallic color, obtaining a nanoclay-modified gallium-indium alloy as the raw material for the stretchable conductive pattern.

[0084] S2. Preparation of stretchable conductive patterns and encapsulation with stretchable substrates:

[0085] Pour an appropriate amount of the above SEBS solution into a glass petri dish and place the petri dish on a level. After the toluene has completely evaporated, carefully tear off the SEBS film, which will serve as the subsequent base layer.

[0086] A laser-cut PET material is provided as a patterned template, and a glass sheet is used as a scraper. The prepared nanoclay-modified gallium-indium alloy is precisely scraped onto the SEBS substrate layer through the patterned PET template, thereby producing a stretchable conductive pattern.

[0087] Then, a 15 wt% concentration of SEBS solution was used to encapsulate the stretchable conductive pattern by spin coating. The specific steps are as follows: first, the above device is flatly attached to the glass substrate, and then placed on the tray of the spin coater. Next, the SEBS solution is dripped in, and the speed of the spin coater is set to 500 rpm, and the spin coating is continued for 30 seconds. After the spin coating is completed, the entire glass substrate is moved to a hot stage and heated for 30 minutes to ensure that the toluene solvent can be completely volatilized, thereby completing the encapsulation and obtaining a stretchable substrate encapsulated with a stretchable conductive pattern.

[0088] S3. Punching process:

[0089] Through the CO2 laser, the stretchable conductive pattern is precisely etched on the stretchable substrate to obtain a through hole. The etching rate is 65% to 80% of the equipment rating, and the power is 10% to 20% of the equipment rating. The diameter of the etched through hole ranges from 10 μm to 40 μm, most of which are around 25 μm, and the depth ranges from 10 μm to 20 μm, most of which are around 15 μm. Such micron-level through holes can prevent liquid metal leakage.

[0090] S4. Forming a stretchable conductor:

[0091] Patterned weighing paper is used as a mask to cover the above device, and the through-hole area is exposed. Gold is precisely evaporated to the specified position, and gold nanoparticles are deposited at the through-hole to obtain a stretchable conductor. One end of the stretchable conductor forms a conductive interface of a solid-liquid metal film with the stretchable conductive pattern of the liquid metal at the bottom of the through-hole, and also forms a BIND interface with the SEBS matrix, and then the three form an HBI interface, while preventing liquid metal leakage. BIND interfaces are formed between the stretchable conductor and the inner wall of the through-hole, and between the other end of the stretchable conductor and the outer surface of the stretchable matrix, with good mechanical stability and electrical stability.

[0092] Through the above steps S1 to S4, the stretchable circuit of this embodiment is manufactured.

[0093] Example 2

[0094] This embodiment provides a stretchable circuit and a method for preparing the same. The only difference from Embodiment 1 is that the gold used for vapor deposition in step S4 is replaced by copper, and a HBI interface can also be formed. The rest is the same.

[0095] Example 3

[0096] This embodiment provides a stretchable circuit and a preparation method thereof, which differs from Embodiment 1 only in that SEBS1221 in step S1 is changed to PDMS, so that the material of the stretchable substrate is changed to PDMS, a BIND interface is still formed between the stretchable substrate and the stretchable conductor, and the three still form an HBI interface, and the rest are the same.

[0097] Example 4

[0098] This embodiment provides a stretchable circuit and a method for preparing the same. The only difference from Embodiment 1 is that the liquid metal in step S1 is modified from nanoclay to copper nanoparticles. The three still form an HBI interface, and the formed stretchable conductive pattern also changes accordingly. The rest is the same.

[0099] Example 5

[0100] This embodiment provides a stretchable circuit and a preparation method thereof, which is different from Embodiment 1 only in that the liquid metal in step S1 is not modified with nanoclay, but directly used as a prepared gallium-indium alloy for the stretchable conductive pattern, and the rest is the same.

[0101] Comparative Example 1

[0102] This comparative example provides a stretchable circuit and a method for preparing the same. The only difference between this comparative example and Example 1 is that the stretchable conductive pattern is changed to a meandering copper foil that can be stretched, and the copper foil also extends through the through hole, and the electronic component is soldered in the through hole area through tin, and the circuit pins of the electronic component are soldered at the through hole position and electrically connected to the copper foil. In order to ensure the soldering effect of tin, the temperature during the soldering process needs to reach about 300°C or even higher. The stretchable substrate is affected by the high temperature, and hot melt deformation occurs near the soldering area. After the temperature drops to room temperature, these areas further harden, resulting in local deformation of the device and affecting the tensile performance.

[0103] Comparative Example 2

[0104] This comparative example provides a stretchable circuit and a preparation method thereof. The only difference between this comparative example and Example 1 is that the stretchable conductive pattern is changed to a meandering copper foil, which can be stretched. At the same time, in step S4, instead of using the evaporation method, commercial silver paste is poured into the through hole and used as an interface to be electrically connected to the circuit pins of the electronic component.

[0105] Comparative Example 3

[0106] This comparative example provides a stretchable circuit and a preparation method thereof. The difference between this comparative example and Example 1 is that no stretchable conductive pattern is set, and no through hole is set. Instead, gold is directly evaporated on the stretchable substrate, and a BIND interface is formed between SEBS and gold. The deposited gold serves as an interface to be electrically connected to the circuit pins of the electronic component.

[0107] Related performance tests and result analysis

[0108] 1. Morphological analysis of stretchable circuits

[0109] The stretchable circuit of Example 1 was subjected to scanning electron microscopy analysis to obtain a SEM image, wherein the SEM image of the non-through hole area of ​​the stretchable circuit is as follows: Figure 4 As shown, it can be seen that the top layer a is the deposited gold extending from the stretchable conductor to the outer surface of the stretchable substrate, which can be used as an interface; the darker middle layer b is the packaging part of the stretchable substrate; the brighter middle and lower layer c is the stretchable conductive pattern formed by the nanoclay modified gallium indium alloy; the bottom layer d is the base part of the stretchable substrate, and only a part of the base is shown in the figure.

[0110] Example 1 SEM image of the through hole of the stretchable circuit Figure 5 As shown in the figure, the marks are made, where a is the deposited gold deposited on the outer surface of the stretchable substrate, b is the deposited gold deposited in the through hole, c is the stretchable substrate of SEBS, and d is the stretchable conductive pattern of the nanoclay-modified gallium-indium alloy. It can be seen that the deposited gold and SEBS are closely combined to form a BIND interface, and the stretchable conductor and the stretchable conductive pattern form a conductive interface of the solid-liquid metal film. Therefore, in the through hole, an HBI interface is formed between SEBS, deposited gold, and nanoclay-modified gallium-indium alloy, which improves the degree of combination, constructs a three-dimensional conductive path, and improves mechanical stability and electrical stability.

[0111] 2. Electrical performance testing of stretchable circuits

[0112] The stretchable circuits of Examples 1 to 5 and Comparative Examples 1 to 3 were subjected to a stretch cycle test. The resistance value was tested during the process. The test instrument used was Keysight 34450a. Both ends of the sample were firmly fixed on an electric translation stage and the sample was stretched at a set speed of 60 mm min. -1 The device was cyclically stretched at a speed of 100 Hz, and the resistance of the stretchable circuit was monitored in real time and continuously using the Keysight 34450a.

[0113] The stretch deformation of the stretchable circuit in Example 1 reaches 50% in each stretching cycle, that is, it is stretched by 50%. The stretching cycle is repeated tens of thousands of times. The test results are as follows: Figure 6 , Figure 7 shown. Figure 6 It can be seen that the resistance value of the stretchable circuit in Example 1 is always less than 0.2 Ω from the initial stretch to tens of thousands of times, and the resistance value is very low, indicating good conductivity; moreover, it can still work after being stretched tens of thousands of times, indicating good stretching durability and long-term use; moreover, the resistance value remains almost unchanged after being stretched tens of thousands of times, indicating good electrical stability.

[0114] Figure 7 The resistance value of the stretching cycle was recorded after more than 5,000 stretching cycles. Figure 7It can be further seen that in each stretching cycle, when the stretchable circuit undergoes 50% stretching deformation, the resistance value of the entire stretchable circuit changes very little, indicating good electrical stability.

[0115] The stretchable circuit of Example 1 was subjected to different stretch deformation tests of 0% to 800%, and the resistance value and resistance change were recorded. Figure 8 R0 in the figure refers to the initial resistance value, and △R is the resistance value when stretched to the stretching deformation minus R0 to obtain the resistance change value, so △R / R0 is the resistance change rate. Figure 8 It can be seen that the stretchable circuit can withstand extremely high tensile deformation, and the resistance change value and resistance change rate are very low. Even if the tensile deformation reaches 800%, the resistance change value is ≤0.16Ω and the resistance change rate is ≤6%. The low resistance change rate indicates good electrical stability.

[0116] According to the above test method, 100 stretching cycle tests were further performed, and the above 100 cycle tests were completed at 50%, 100%, 200%, 400%, 600%, and 800% stretching deformations, respectively. The results of Example 1 are as follows: Fig. 9 As shown, Fig. 9 It can be seen that the stretchable circuit of Example 1 can withstand various degrees of deformation, and can undergo 100 stretching cycles at a stretching deformation of 800%, and the resistance value changes very little, indicating that the electrical stability is extremely strong, and the resistance value is always less than 0.2 Ω, which is very low and has good conductivity.

[0117] The stretchable circuit of Comparative Example 3 was also subjected to 100 stretching cycle tests, with each stretching deformation reaching 100%. The results are as follows: Fig. 9 As shown, Fig. 9 The mark of SEBS-Au strain in is the test result of comparative example 3. It can be seen that although the stretchable circuit of comparative example 3 also contains the BIND interface of SEBS-Au and can be stretched to a certain extent, it does not contain the stretchable conductive pattern of nanoclay-modified liquid metal and only relies on deposited gold for conduction. The resistance value of the stretchable circuit when not stretched is about 100 Ω, which is very high. Fig. 9 It can also be seen that as the tensile deformation reaches 100%, the resistance value increases rapidly, reaching nearly 1000 Ω. It can be seen that as the tensile deformation increases, the resistance value increases significantly. The electrical stability of comparative example 3 is poor, which is obviously not as good as the above test results of embodiment 1 in which the HBI interface is introduced.

[0118] In addition, during each stretching cycle of the stretchable circuits of Comparative Examples 1 and 2, as the stretching deformation occurs, the stretchable circuits are elongated, the resistance increases significantly, and they are prone to failure after the stretching cycle. They fail electrically at a stretching deformation of 50%, and the test is not completed, so they cannot meet the requirements of flexible electronic integration. It can be seen that the electrical stability of Comparative Examples 1 and 2 is poor.

[0119] 3. Performance testing of stretchable circuits combined with electronic components

[0120] The stretchable circuits of Examples 1 to 5 and Comparative Example 3 are connected to electronic components, specifically, a modified LED lamp, a SEBS film is formed in situ on the back of the LED lamp, and nano-gold is deposited to form a BIND interface on the back of the LED, and then the back of the LED lamp is faced toward the stretchable circuit and pressed on the interface of the stretchable circuit to make the nano-gold (or copper) of the stretchable circuit contact and conduct electricity with the nano-gold on the back of the LED lamp, and the stretchable circuits of Examples 1 to 5 form a HBI-BIND interface with the LED lamp, and the stretchable circuit of Comparative Example 3 forms a BIND-BIND interface with the LED lamp.

[0121] Then the shear strength and interface toughness were tested. The test instrument used was MTS Criterion C42. The stretchable circuit was tightly combined with the modified LED lamp by simply pressing it and maintaining this state for about 2 minutes to ensure that the interface between the materials was in full contact. When performing the peel and lap shear tests, the two ends of the sample were fixed on the pneumatic clamps respectively. Then, the sample was clamped at 12 mm min. -1 The stretching was performed at a constant stretching rate until the stretchable circuit and the LED lamp were completely separated. During the entire stretching process, the stress changes were recorded in detail. The adhesion test was performed without cycles. The test results of Example 1 and Comparative Example 3 are shown in FIG. Fig.10 As shown, it can be seen that the HBI-BIND interface of Example 1 has extremely strong shear strength and interface toughness, and its mechanical properties are slightly better than those of the existing BIND-BIND interface, and are similar overall.

[0122] Combined with the test results of the above electrical properties, it can be seen that compared with the comparative example with only the BIND interface, Example 1 introduces through holes and HBI interfaces in the stretchable circuit, which greatly improves the electrical properties such as conductivity and electrical stability without reducing the mechanical stability of the stretchable circuit.

[0123] Fig.11This is a comparison chart of the electrical stretch rate and mechanical stretch rate of the stretchable circuit of Comparative Example 3 and other conventional structures combined with the above-mentioned LED lamp in the existing research, where the BIND-BIND mark is the Comparative Example 3 combined with the LED lamp. It can be seen that the electrical stretch rate and mechanical stretch rate of the stretchable circuit combined with the LED lamp of Comparative Example 3 are much higher than those of other conventional structures, but the most ideal electrical stretch rate is only 180%, which is obviously not as good as the test result of the above-mentioned Example 1, which further proves that compared with the stretchable circuit with only the BIND interface, the electrical stability of Example 1 is significantly improved after the HBI interface is introduced.

[0124] In addition, after the stretching cycle and 100% stretching deformation, the mechanical properties of the stretchable circuits of Comparative Examples 1 and 2 fail at the interface and cannot be restored. The test is not completed and the requirements of flexible electronic integration cannot be met. It can be seen that the mechanical stability of Comparative Examples 1 and 2 is poor.

[0125] 4. Functionality

[0126] When the stretchable circuits of Examples 1 to 5 are used for flexible electronic integration, the electronic components can be adhered to the outer surface of the stretchable substrate in the area where the through holes are located, and the circuit pins and other components of the electronic components can be electrically connected to the interface of the stretchable circuit. The adhered electronic components can be removed and new electronic components can be adhered to the corresponding positions. This process will not damage the interface of the stretchable circuit, so that another flexible electronic integrated system is obtained by replacing the electronic components, which has high functionality and flexibility.

[0127] When the stretchable circuits of Comparative Examples 1 and 2 are used for flexible electronic integration, the electronic components are fixed at the interface positions and cannot be flexibly replaced with new electronic components, and the functionality and flexibility are poor.

[0128] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A stretchable circuit, characterized in that: The invention comprises a stretchable substrate, wherein a stretchable conductive pattern is encapsulated inside the stretchable substrate, and the stretchable substrate is provided with a plurality of through holes; at least part of the through holes extend from the outer surface of the stretchable substrate to the stretchable conductive pattern, and a stretchable conductor is filled in the through holes, and one end of the stretchable conductor is connected to the stretchable conductive pattern, and the other end extends to the outer surface of the stretchable substrate; The material of the stretchable conductor includes at least one of deposited gold, deposited silver, deposited chromium, and deposited copper; The material of the stretchable conductive pattern includes at least one of liquid metal, nanomaterial-modified liquid metal, and liquid conductive organic matter; A two-phase nano-dispersed interface is formed between the stretchable conductor and the stretchable substrate, and a solid-liquid conductive interface is formed between the stretchable conductor and the stretchable conductive pattern; so that in the through hole, the stretchable conductor, the stretchable conductive pattern, and the stretchable matrix form a mixed two-phase interface; The stretchable circuit satisfies at least one of the following features (1) to (3): (1) Resistance value ≤ 0.2 Ω; (2) When the tensile deformation is 50% and the tensile cycle is within 10,000 times, the resistance change rate is ≤2.5%; (3) When the tensile deformation is 800%, the resistance change rate is ≤6%.

2. The stretchable circuit according to claim 1, characterized in that: The material of the stretchable substrate includes at least one of SEBS, PDMS, and ECOFLEX.

3. The stretchable circuit according to claim 1 or 2, characterized in that: at least a portion of the stretchable conductor fills the through hole; And / or, the end portion of the stretchable conductor extending to the outer surface of the stretchable substrate is film-shaped and adheres to the outer surface of the stretchable substrate.

4. The stretchable circuit according to claim 1 or 2, characterized in that: The through hole has a diameter of 1 to 50 μm; And / or, the depth of the through hole is 10 to 30 μm; And / or, the number of the through holes is ≥2, and the through holes are arranged at intervals.

5. The stretchable circuit according to claim 1 or 2, characterized in that: The thickness of the stretchable conductive pattern is 1 to 20 μm; And / or, the thickness of the stretchable substrate is 150-300 μm.

6. A method for preparing a stretchable circuit as claimed in any one of claims 1 to 5, characterized in that: The steps include: encapsulating the stretchable conductive pattern inside the stretchable substrate; Punching the stretchable substrate to form a plurality of through holes; The raw material of the stretchable conductor is subjected to a molding process at the position of the through hole to form the stretchable conductor.

7. The preparation method according to claim 6, characterized in that: The punching process includes laser etching process; And / or, the molding process includes at least one of evaporation, sputtering, and deposition.

8. A flexible electronic integrated system, characterized in that: It includes an electronic component and also includes a stretchable circuit as described in any one of claims 1 to 5 or a stretchable circuit prepared by the preparation method as described in claim 6 or 7, and the circuit pins of the electronic component are connected to the stretchable conductor of the stretchable circuit.

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