A highly adhesive flexible substrate and its processing method

Abstract

The present invention discloses a highly adhesive flexible substrate and a processing method thereof, belonging to the technical field of flexible electronic device processing. It includes: a flexible substrate, and a micron-level vacuum suction cup array is uniformly distributed on the surface of the flexible substrate for contacting with electronic functional components. The highly adhesive flexible substrate provided by the present invention forms a vacuum suction cup array on the flexible substrate, and utilizes the adsorption effect between the vacuum suction cup and the electronic functional component to form a stable adhesion during processing and integration, enhancing the adhesion between the flexible substrate and the electronic functional component, and improving the service life of the flexible electronic device. At the same time, the vacuum suction cup array is micron-level, with small size and uniform distribution, and has stronger adhesion to the electronic functional component.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible electronic device processing, and particularly relates to a highly adhesive flexible substrate and a processing method thereof. Background Art

[0002] In recent years, stretchable flexible electronic devices have received extensive attention in the fields of medical and health monitoring, brain-computer integration, etc. due to their unique flexibility, stretchability, and high performance. During the service process of stretchable flexible electronic devices, they inevitably need to withstand large deformations. However, there are huge differences in mechanical properties between the internal electronic functional components and the flexible substrate. Therefore, the interfacial failure between the electronic functional components and the flexible substrate is an issue that cannot be ignored. However, flexible substrates often use materials with good biocompatibility such as silicone rubber and hydrogel, and these materials usually have weak surface adhesion. Generally, surface modification and surface microstructure are two ways to enhance the surface adhesion of flexible substrates, but the adhesion enhancement effects of both are limited. Summary of the Invention

[0003] The purpose of the present invention is to provide a highly adhesive flexible substrate and a processing method thereof, which solve the problem that the adhesion between the flexible substrate and the electronic functional components in flexible electronic devices is not strong, resulting in a short service life of flexible electronic devices.

[0004] The present invention is achieved by the following technical solutions:

[0005] The present invention provides a highly adhesive flexible substrate, including: a flexible substrate, and a micron-level vacuum suction cup array is uniformly distributed on the surface of the flexible substrate for contacting with electronic functional components.

[0006] Further, in the highly adhesive flexible substrate, the vacuum suction cup array includes: cylindrical protrusions distributed in an array on the surface of the flexible substrate for contacting with electronic functional components, and vacuum suction cups are connected to the protrusions.

[0007] Further, in the highly adhesive flexible substrate, the flexible substrate and the vacuum suction cup array are made of silicone rubber or hydrogel.

[0008] Further, in the highly adhesive flexible substrate, the distribution shape of the vacuum suction cup array is rectangular or circular.

[0009] The present invention also provides a processing method for a highly adhesive flexible substrate, including:

[0010] Prepare an initial mold with microstructures distributed in an array, stretch the initial mold to obtain a target mold, use the target mold as the bottom plate to make a flexible substrate with the same array-distributed microstructures as the target mold, and cure a flexible film on the array-distributed microstructures of the flexible substrate by pressurization and heating. After releasing the pressure, a vacuum chuck array is formed to obtain the flexible substrate with high adhesion.

[0011] Further, the processing method of the flexible substrate with high adhesion includes:

[0012] Prepare a first mold, and process cylindrical pits distributed in an array on the surface of the first mold;

[0013] Prepare a second mold, which is made by adapting to the first mold. The second mold has cylindrical protrusions distributed in an array corresponding to the cylindrical pits of the first mold;

[0014] Apply a radial tensile load to the periphery of the second mold. Under the action of the radial tensile load, the bottom of the cylindrical protrusion on the second mold expands in the radial direction, and the top of the cylindrical protrusion is not affected by the load. The asymmetric load on the bottom and the top of the cylindrical protrusion causes the cylindrical protrusion to bend and deform, and a groove is formed at the top of the cylindrical protrusion on the second mold;

[0015] Prepare a third mold, keep the radial tensile load around the second mold, and prepare the third mold by adapting to the second mold. The shape of the microstructure on the surface of the third mold is opposite to the shape of the microstructure on the surface of the deformed second mold;

[0016] Prepare a flexible substrate, and prepare the flexible substrate by adapting to the second mold. The shape of the microstructure on the surface of the flexible mold is the same as the shape of the microstructure on the surface of the deformed second mold;

[0017] Place an incompletely cured flexible film on the top of the protrusion of the flexible substrate, cure it by pressurization and heating, and bond the flexible film to the surface microstructure of the flexible substrate;

[0018] Release the pressure, the microstructure on the surface of the flexible substrate recovers, the flexible film is completely deformed, and a vacuum chuck is formed with the groove at the top of the cylindrical protrusion on the second mold, that is, a vacuum chuck array is prepared on the surface of the flexible substrate.

[0019] Further, in the processing method of the flexible substrate with high adhesion, the material of the first mold is quartz, glass or resin; the material of the first mold is subjected to silanization treatment.

[0020] Further, in the processing method of the flexible substrate with high adhesion, the material of the second mold is silicone rubber.

[0021] Furthermore, in the method for processing the highly adhesive flexible substrate, the third mold material is a photocurable resin.

[0022] The present invention also provides an application of the above-mentioned highly adhesive flexible substrate in the preparation of flexible electronic devices.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] The highly adhesive flexible substrate provided by the present invention forms a vacuum suction cup array on the flexible substrate, and utilizes the adsorption effect between the vacuum suction cup and the electronic functional element to form a stable adhesion during processing and integration, enhancing the adhesion between the flexible substrate and the electronic functional element, and improving the service life of the flexible electronic device. At the same time, the vacuum suction cup array is in the micron level, small in size and evenly distributed, and has a stronger adhesion force with the electronic functional element.

[0025] The method for processing the highly adhesive flexible substrate provided by the present invention prepares a micron-sized vacuum suction cup array on the surface of the flexible substrate by combining micro-nano processing technology and mechanical loading. The adhesion between the flexible substrate and the electronic functional element is enhanced through the vacuum suction cup array, and the service life of the flexible electronic device is improved. This processing method is simple, fast and efficient, and is particularly suitable for the preparation of inorganic flexible electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts. In the drawings:

[0027] Figure 1 is a schematic structural diagram of a flexible electronic device assembled from the highly adhesive flexible substrate and electronic functional elements of the present invention;

[0028] Figure 2 is a flowchart of the method for processing the highly adhesive flexible substrate of the present invention.

[0029] Marks in the drawings and corresponding component names:

[0030] 1 - Flexible substrate, 11 - Protrusion, 12 - Vacuum suction cup, 2 - Electronic functional element, 3 - First mold, 4 - Second mold, 5 - Third mold. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the embodiments and the accompanying drawings. The illustrative embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not indicating the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0032] The technical solution of the present invention is as follows:

[0033] A highly adhesive flexible substrate includes: a flexible substrate, and a micron-level vacuum suction cup array is uniformly distributed on the surface of the flexible substrate for contacting with electronic functional components. The vacuum suction cup array includes: cylindrical protrusions distributed in an array on the surface of the flexible substrate for contacting with electronic functional components, and vacuum suction cups are connected to the protrusions. The cross-section of the suction cup is circular, and the force is more evenly distributed during bonding, and the bonding is more firm. The flexible substrate and the vacuum suction cup array are made of silicone rubber or hydrogel.

[0034] For this highly adhesive flexible substrate, by forming a vacuum suction cup array on the flexible substrate, a firm adhesion is formed by the adsorption action of the vacuum suction cups and the electronic functional components during processing and integration, enhancing the adhesion between the flexible substrate and the electronic functional components, and improving the service life of the flexible electronic device. At the same time, the vacuum suction cup array is micron-level, with small size and uniform distribution, and has a stronger adhesion to the electronic functional components.

[0035] A method for processing a highly adhesive flexible substrate includes:

[0036] Preparing an initial mold with a micro-structure distributed in an array, stretching the initial mold to obtain a target mold, using the target mold as a bottom plate to make a flexible substrate with the same micro-structure distributed in an array as the target mold, curing a flexible film on the micro-structure distributed in an array of the flexible substrate by pressurization and heating, and forming a vacuum suction cup array after releasing the pressure to obtain the highly adhesive flexible substrate.

[0037] Specifically, the method for processing a highly adhesive flexible substrate includes:

[0038] Prepare the first mold. Cylindrical pits are machined on the surface of the first mold and are distributed in an array. The cylindrical structure is more uniformly stressed during the subsequent radial load stretching process, with uniform deformation around, making it suitable as an isotropic suction cup. Among them, the material of the first mold is quartz, glass or resin, which has stable physical and chemical properties and is easy to etch, facilitating microstructure processing with high precision. The material of the first mold is subjected to silanization treatment, which facilitates the demolding of the subsequent second mold. The size of the cylindrical pits machined on the first mold and distributed in an array is at the micron level, and the processing methods can include dry etching, focused ion beam etching, 3D printing, etc. The processed array can be distributed in a rectangular or circular shape.

[0039] Prepare the second mold, which is obtained through the matching first mold. The second mold has cylindrical protrusions corresponding to the array distribution of the cylindrical pits on the first mold. Among them, the material of the second mold is silicone rubber, specifically polydimethylsiloxane can be used. The preparation process of the second mold includes: pouring the mixed and defoamed polydimethylsiloxane liquid onto the surface of the first mold, defoaming again, heating and curing, and then demolding. Liquid polydimethylsiloxane silicone rubber has good fluidity and fast curing, is suitable for high-precision replication of microstructures, and the cured polydimethylsiloxane silicone rubber has moderate strength and hardness and strong deformation ability, making it suitable for stretching.

[0040] Apply a radial tensile load to the periphery of the second mold. Under the action of the radial tensile load, the bottom of the cylindrical protrusion on the second mold expands in the radial direction, and the top of the cylindrical protrusion is not subjected to the load. The asymmetric load on the bottom and the top of the cylindrical protrusion causes the cylindrical protrusion to bend and deform, and a groove is formed at the top of the cylindrical protrusion.

[0041] Prepare the third mold. Keep the radial tensile load on the periphery of the second mold and prepare the third mold through the matching second mold. The shape of the microstructure on the surface of the third mold is opposite to the shape of the microstructure on the surface of the deformed second mold. The material of the third mold is photocurable resin. The preparation process of the third mold includes: pouring the photocurable resin solution onto the surface of the second mold, placing it in an ultraviolet curing device for curing and then demolding. Liquid photocurable resin has good fluidity and can be cured by ultraviolet irradiation. The cured photocurable resin has low surface energy and is easy to demold, making it suitable for high-precision replication of microstructures.

[0042] Prepare the flexible substrate, which is prepared through the matching third mold. The shape of the microstructure on the surface of the flexible mold is the same as the shape of the microstructure on the surface of the deformed second mold.

[0043] Place an incompletely cured flexible film on the top of the protrusion of the flexible substrate, apply pressure and heat for curing, and bond the flexible film to the microstructure on the surface of the flexible substrate. The shape of the flexible film can be circular and has a certain thickness.

[0044] The pressure is released, the microstructure on the surface of the flexible substrate is restored, the flexible film is completely deformed, and a vacuum suction cup is formed with the top groove of the cylindrical protrusion on the second mold, that is, an array of vacuum suction cups is prepared on the surface of the flexible substrate.

[0045] In this preparation method, the first mold is a hard mold, made of a material with stable physical and chemical properties and easy to etch, facilitating microstructure processing with high precision. Using the first mold as the processing mold to make the second mold, the first mold is cleaned and pretreated with siloxane to facilitate the demolding of the second mold. The second mold is a silicone rubber mold. Liquid polydimethylsiloxane silicone rubber has good fluidity and fast curing, suitable for high-precision replication of microstructures. The cured polydimethylsiloxane silicone rubber has moderate strength and hardness and strong deformation ability, suitable for stretching. Using the second mold as the processing mold to make the third mold, the third mold is a photocurable resin mold. Liquid photocurable resin has good fluidity and can be cured by ultraviolet irradiation. The surface energy of the cured photocurable resin is low and easy to demold, suitable for high-precision replication of microstructures.

[0046] Example 1:

[0047] Please refer to Figure 1 , this example provides a flexible substrate with high adhesion, including that the surface of the flexible substrate for contacting with electronic functional components is evenly distributed with a micron-level array of vacuum suction cups. The flexible substrate 1 and the vacuum suction cup array are made of silicone rubber or hydrogel. The vacuum suction cup array includes: protrusions 11 distributed in an array on the surface of the flexible substrate 1 for contacting with electronic functional components, and vacuum suction cups 12 are connected to each of the protrusions 11.

[0048] Example 2:

[0049] Please refer to Figure 1 and 2 , the processing method of the flexible substrate with high adhesion provided in this example includes:

[0050] The first step: Prepare the first mold 3 (hard mold) with cylindrical pits of micron size on the surface:

[0051] The first mold 3 is the initial mold for preparing a micron-sized array of vacuum suction cups on the surface of the flexible substrate 1. Usually, a material with stable physical and chemical properties and easy to etch is selected, such as quartz, silicon materials, etc. The process for machining the cylindrical pits on the surface of the first mold 3 includes dry etching, focused ion beam etching, 3D printing, etc.

[0052] The second step: Prepare the second mold 4 (polydimethylsiloxane (PDMS) mold) with cylindrical protrusions of micron size on the surface:

[0053] The cleaned first mold 3 is subjected to silanization treatment, and the mixed and defoamed PDMS liquid is poured onto the surface of the silanized first mold 3, defoamed and cured again, and the second mold 4 is peeled off from one side to complete the preparation of the second mold 4 with micron-sized cylindrical protrusions 11 on the surface.

[0054] Step 3: Deform the cylindrical protrusion 11 on the surface of the second mold 4:

[0055] A radial tensile load is applied around the second mold 4. The bottom of the cylindrical protrusion 11 expands in the radial direction under the radial tensile load, and the top of the cylindrical protrusion 11 is not subjected to the load. The asymmetric load causes the cylindrical protrusion 11 to bend and deform, and a groove is formed on the top.

[0056] Step 4: Prepare the third mold 5 (light-curing resin mold):

[0057] Maintaining the radial tensile load around the second mold 4, pouring the photocurable resin solution onto the surface of the second mold 4, defoaming, UV curing, and demolding, a third mold 5 is obtained. The microstructure shape of the surface of the photocurable resin mold 4 is opposite to the microstructure shape of the surface of the deformed second mold 4.

[0058] Step 5: Prepare flexible substrate 1:

[0059] Pour the silicone rubber or hydrogel liquid into the third mold 5, defoam, cure, and demould to obtain a flexible substrate 1, wherein the microstructure shape on the surface of the flexible substrate 1 is the same as the microstructure shape on the surface of the deformed second mold 4;

[0060] Step 6: Bonding the flexible substrate 1 and the flexible film:

[0061] The flexible substrate 1 is placed on the surface of an incompletely cured circular flexible film, and pressure is applied to the surface of the flexible substrate 1 to deform the microstructure and make it fully contact with the circular flexible film. The pressure on the surface of the flexible substrate 1 is maintained, and the film is heated and cured so that the flexible film and the microstructure on the surface of the flexible substrate 1 are firmly bonded together.

[0062] Step 7: Prepare a flexible substrate 1 having an array of micron-sized vacuum suction cups 12 on its surface.

[0063] The pressure is released, and the microstructure on the surface of the flexible substrate 1 returns to its original shape, causing the circular flexible film array to bend and deform, changing into a vacuum suction cup 12 structure, thereby obtaining a flexible substrate 1 having a micron-sized vacuum suction cup 12 array on the surface.

[0064] The process of integrating the electronic functional element 2 with the flexible substrate 1 having an array of micron-sized vacuum chucks 12 on the surface includes the following steps:

[0065] Step 1: Place the flexible substrate 1 with a micron-sized vacuum chuck 12 array on the surface of the electronic functional element 2, and ensure good contact between the micron-sized vacuum chuck 12 array on the surface of the flexible substrate 1 and the electronic functional element 2.

[0066] Step 2: Slowly apply pressure to the surface of the flexible substrate 1 to deform the vacuum chuck 12 array, and air flows out from the cavity formed by the vacuum chuck 12 array and the electronic functional element 2. The pressure in the cavity decreases, enhancing the adhesion at the interface between the electronic functional element 2 and the flexible substrate 1.

[0067] Example 3

[0068] Please refer to Figure 1 , this example provides a flexible electronic device, which is fabricated and integrated with the electronic functional element 2 using the highly adhesive flexible substrate 1 in Example 1. The vacuum chuck array on the surface of the flexible substrate 1 is in good contact with the electronic functional element.

[0069] Slowly apply pressure to the surface of the flexible substrate to deform the vacuum chuck array, squeezing the air in the cavity formed by the vacuum chuck array and the electronic functional element. The pressure in the cavity decreases, and the vacuum chuck array is in close contact with the electronic functional element, realizing the fabrication and integration of the flexible substrate and the electronic functional element.

[0070] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A highly adhesive flexible substrate, characterized in that, it includes: A flexible substrate, on the surface of the flexible substrate for contacting with electronic functional components, a micron-level vacuum suction cup array is evenly distributed; The processing method of the highly adhesive flexible substrate includes: preparing an initial mold with an array-distributed microstructure, stretching the initial mold to obtain a target mold, using the target mold as a bottom plate to make a flexible substrate with the same array-distributed microstructure as the target mold, curing a flexible film on the array-distributed microstructure of the flexible substrate by pressurization and heating, and forming a vacuum suction cup array after releasing the pressure to obtain the highly adhesive flexible substrate.

2. The highly adhesive flexible substrate according to claim 1, characterized in that, The vacuum suction cup array includes: cylindrical protrusions distributed in an array on the surface of the flexible substrate for contacting with electronic functional components, and vacuum suction cups are connected to the protrusions.

3. The highly adhesive flexible substrate according to claim 1 or 2, characterized in that, Both the flexible substrate and the vacuum suction cup array are made of silicone rubber or hydrogel.

4. The highly adhesive flexible substrate according to claim 1 or 2, characterized in that, The shape of the distribution of the vacuum suction cup array is rectangular or circular.

5. The highly adhesive flexible substrate according to claim 1, characterized in that, it includes: Preparing a first mold, on the surface of the first mold, cylindrical pits are machined in an array; Preparing a second mold, which is made by adapting to the first mold, and the second mold has cylindrical protrusions corresponding to the cylindrical pits of the first mold and distributed in an array; Applying a radial tensile load to the periphery of the second mold. Under the action of the radial tensile load, the bottom of the cylindrical protrusion on the second mold expands in the radial direction, the top of the cylindrical protrusion is not affected by the load, and the asymmetric load on the bottom and the top of the cylindrical protrusion causes the cylindrical protrusion to bend and deform, and a groove is formed at the top of the cylindrical protrusion on the second mold; Preparing a third mold, keeping the radial tensile load around the second mold, and preparing a third mold by adapting to the second mold, and the microstructure shape on the surface of the third mold is opposite to the microstructure shape on the surface of the deformed second mold; Preparing a flexible substrate, preparing a flexible substrate by adapting to the second mold, and the microstructure shape on the surface of the flexible mold is the same as the microstructure shape on the surface of the deformed second mold; Placing an incompletely cured flexible film on the top of the protrusion of the flexible substrate, curing by pressurization and heating, and bonding the flexible film to the microstructure on the surface of the flexible substrate; Releasing the pressure, the microstructure on the surface of the flexible substrate recovers, the flexible film is completely deformed, and forms a vacuum suction cup with the groove at the top of the cylindrical protrusion on the second mold, that is, a vacuum suction cup array is prepared on the surface of the flexible substrate; The initial mold is the second mold, and the target mold is the third mold.

6. The highly adhesive flexible substrate according to claim 5, characterized in that, The material of the first mold is quartz, glass or resin; the material of the first mold is subjected to silanization treatment.

7. The highly adhesive flexible substrate according to claim 5, wherein, the second mold material is silicone rubber.

8. The highly adhesive flexible substrate according to claim 5, wherein, the third mold material is a photocurable resin.

9. Application of the highly adhesive flexible substrate according to any one of claims 1-4 in the preparation of flexible electronic devices.

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