Flexible packaging substrate and preparation method thereof

Abstract

In order to overcome the problems of poor air tightness, electrical performance and mechanical strength of the existing flexible packaging substrate, the invention provides a flexible packaging substrate which comprises packaging material layers and insulating layers which are sequentially and alternately stacked, the packaging material layer comprises a liquid metal-polymeric elastomer packaging layer and a base material, the liquid metal-polymeric elastomer packaging layer is arranged on the surface of the base material, and the liquid metal-polymeric elastomer packaging layer comprises liquid metal and a polymeric elastomer which are mixed with each other; according to the invention, the liquid metal is used as a main packaging material and is compounded with the high-molecular elastomer material to form a composite packaging layer with high air tightness and excellent tensile property; the flexible packaging substrate provided by the invention can be widely applied to flexible electronic systems such as wearable electronic equipment, flexible display screens, flexible solar cells and the like, a new solution is provided for the field of flexible electronic packaging, and the application range and the market prospect of the flexible electronic equipment are greatly expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic equipment, and in particular to a flexible packaging substrate and a preparation method thereof. Background Art With the rapid development of electronic devices, especially the widespread application of flexible electronic technology in wearable devices, flexible displays, medical sensors and other fields, the demand for flexible packaging substrates is growing. Traditional rigid packaging substrates are difficult to adapt to the complex deformations such as bending and twisting encountered by flexible electronic devices in actual use due to their lack of stretchability, which limits the design and performance of flexible electronic devices.

[0002] At present, flexible packaging substrates mainly use flexible polymer materials. Although they have certain bendability, they often have deficiencies in airtightness, electrical performance and mechanical strength. In addition, the existing technology also faces challenges in realizing the wireless communication function of the packaging substrate, which limits the intelligent and networked development of flexible electronic devices. Therefore, how to overcome the above-mentioned technical problems and defects has become a key issue that needs to be solved. Summary of the invention

[0003] Aiming at the problem that the air tightness, electrical performance and mechanical strength of a flexible packaging substrate are poor, the present invention provides a flexible packaging substrate.

[0004] The technical solution adopted by the present invention to solve the above technical problems is as follows: On the one hand, the present invention provides a flexible packaging substrate, comprising packaging material layers and insulating layers alternately stacked in sequence; the packaging material layers include a liquid metal-polymer elastomer packaging layer and a substrate, the liquid metal-polymer elastomer packaging layer is arranged on the surface of the substrate, and the liquid metal-polymer elastomer packaging layer includes liquid metal and polymer elastomer mixed with each other.

[0005] Optionally, the insulating layer includes a die-bonding adhesive; and the thickness of the insulating layer is 10-25 um.

[0006] Optionally, the substrate includes one or more of a silicon substrate and polyethylene terephthalate; and the thickness of the substrate is 50-150 um.

[0007] Optionally, a plurality of glass balls are arranged on the surface of the substrate, and the glass balls are embedded in the liquid metal-polymer elastomer encapsulation layer; the diameter of the glass balls is 10-30 μm; and the distance between two adjacent glass balls is 10-30 μm.

[0008] Optionally, taking the total mass of the liquid metal-polymer elastomer encapsulation layer as 100%, the percentage of the liquid metal in the total mass of the liquid metal-polymer elastomer encapsulation layer is 50%-70%; the percentage of the polymer elastomer in the total mass of the liquid metal-polymer elastomer encapsulation layer is 30%-50%.

[0009] Optionally, the liquid metal includes a gallium-indium eutectic alloy, and based on the total mass of the gallium-indium eutectic alloy being 100%, the percentage of gallium element in the total mass of the gallium-indium eutectic alloy is 20%-30%; the percentage of indium element in the total mass of the gallium-indium eutectic alloy is 70%-80%; the polymer elastomer includes one or more of polyimide polydimethylsiloxane and polylysine.

[0010] Optionally, a communication module is further included, and an embedding groove is provided on the packaging material layer, and the communication module is embedded in the embedding groove.

[0011] Optionally, a conductive pattern is provided between the packaging material layer and the insulating layer.

[0012] Another aspect of the present invention provides a method for preparing a flexible packaging substrate, comprising the following steps: The liquid metal and the polymer elastomer are mixed evenly to prepare a composite material; Laying the composite material on the substrate and forming a packaging material layer by high temperature hot pressing; The multiple packaging material layers and the multiple insulation layers are alternately stacked in sequence, and conductive patterns are arranged between adjacent packaging material layers and insulation layers.

[0013] Optionally, the step of “laying the composite material on the glass ball array layer and forming a packaging material layer by high temperature hot pressing” includes the following steps: A plurality of glass balls are arranged on the surface of the substrate; The composite material is rolled multiple times to form a uniform liquid metal-polymer elastomer encapsulation layer, the liquid metal-polymer elastomer encapsulation layer is laid on a glass ball, and a laminator is used to form an encapsulation material layer at 100-160°C and a pressure of 5-10MPa; or, the composite material is directly poured on the glass ball; and cured for 0.5-2h at 120-180°C and a pressure of 1-5MPa through a hot pressing process to form an encapsulation material layer.

[0014] Optionally, before the step of “alternating and stacking the multiple packaging material layers and the multiple insulation layers in sequence”, the following steps are also included: An embedding groove is provided on the packaging material layer, and the communication module is embedded in the embedding groove; The gap between the communication module and the corresponding embedding groove is filled with conductive glue and sealant.

[0015] According to the flexible packaging substrate provided by the present invention, liquid metal and polymer elastomer material are compounded to form a composite packaging layer with high air tightness and excellent stretchability; its application scenarios are broadened, laying a solid foundation for the commercialization and wide application of flexible electronic devices, and greatly expanding the application scope and market prospects of flexible electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 It is a schematic diagram of the process of manufacturing a flexible packaging substrate provided by an embodiment of the present invention; DETAILED DESCRIPTION In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0018] In the description of the present invention, it should be understood that the terms "longitudinal", "radial", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0019] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0020] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the materials and reagents used are reagents and materials that can be obtained from commercial channels unless otherwise specified.

[0021] On the one hand, the present invention provides a flexible packaging substrate, comprising packaging material layers and insulating layers alternately stacked in sequence; the packaging material layer comprises a liquid metal-polymer elastomer packaging layer and a substrate, the liquid metal-polymer elastomer packaging layer is arranged on the surface of the substrate, and the liquid metal-polymer elastomer packaging layer comprises liquid metal and polymer elastomer mixed with each other.

[0022] Liquid metal is liquid at room temperature or higher, and has high electrical conductivity, high thermal conductivity, high fluidity and good biocompatibility; common room temperature liquid metals mainly include cesium, francium, rubidium, mercury and gallium.

[0023] The present invention uses liquid metal as the main packaging material and compounds it with a polymer elastic material to form a composite packaging layer that has both high air tightness and excellent stretchability.

[0024] The flexible packaging substrate provided by this invention can be widely used in flexible electronic systems such as wearable electronic devices, flexible display screens, flexible solar cells, etc., providing a new solution for the field of flexible electronic packaging and greatly expanding the application scope and market prospects of flexible electronic devices.

[0025] In one embodiment, the insulating layer includes a die-bonding adhesive; the thickness of the insulating layer is 10-25 um; and / or The substrate comprises one or more of a silicon substrate and polyethylene terephthalate; the thickness of the substrate is 50-150 um.

[0026] In a preferred embodiment, the thickness of the insulating layer is 15-20um. Specifically, the thickness of the insulating layer is any point value among 10um, 11um, 12um, 13um, 14um, 15um, 16um, 17um, 18um, 19um, 20um, 21um, 22um, 23um, 24um or 25um, or a range value consisting of any two point values.

[0027] When the thickness of the insulating layer is 10-25um, the technical effect of good electrical performance of the substrate and the communication module can be achieved; when the thickness of the insulating layer is less than 10um, there will be a short circuit risk in the product reliability test; when the thickness of the insulating layer is greater than 25um, the product thickness will be thicker, affecting the overall tensile performance.

[0028] In a preferred embodiment, the thickness of the substrate is 80-100um. Specifically, the thickness of the substrate is 50um, 55um, 60um, 65um, 70um, 75um, 80um, 85um, 90um, 95um, 100um, 105um, 110um, 115um, 120um, 125um, 130um, 135um, 140um, 145um or 150um, or a range value consisting of any two point values.

[0029] When the thickness of the substrate is 50-150um, a better flexibility effect can be achieved; when the thickness of the substrate is less than 50um, the insulation performance of the product will be poor; when the thickness of the substrate is greater than 150um, the product thickness will be too thick, affecting the application.

[0030] In one embodiment, a plurality of glass balls are disposed on the surface of the substrate, and the glass balls are embedded in the liquid metal-polymer elastomer encapsulation layer; the diameter of the glass balls is 10-30 μm; and the distance between two adjacent glass balls is 10-30 μm.

[0031] Specifically, a plurality of glass balls are arranged in an array on the surface of a substrate. In the present invention, a plurality of glass balls are provided on one side of the substrate. The plurality of glass balls serve as a support body to support the composite packaging layer, thereby preventing the composite packaging layer from collapsing during use, thereby maintaining its sealing performance, ensuring the long-term stability of the packaging material, and improving the reliability and durability of the packaging substrate.

[0032] In a preferred embodiment, the diameter of the glass ball is 15-25 μm. Specifically, the diameter of the glass ball is any point value among 10um, 11um, 12um, 13um, 14um, 15um, 16um, 17um, 18um, 19um, 20um, 21um, 22um, 23um, 24um, 25um, 26um, 27um, 28um, 29um or 30um, or a range value consisting of any two point values.

[0033] In a preferred embodiment, the distance between two adjacent glass balls is 15-25 μm. Specifically, the distance between two adjacent glass balls is any point value among 10um, 11um, 12um, 13um, 14um, 15um, 16um, 17um, 18um, 19um, 20um, 21um, 22um, 23um, 24um, 25um, 26um, 27um, 28um, 29um or 30um, or a range value consisting of any two point values.

[0034] In one embodiment, taking the total mass of the liquid metal-polymer elastomer encapsulation layer as 100%, the percentage of liquid metal in the total mass of the liquid metal-polymer elastomer encapsulation layer is 50%-70%; the percentage of polymer elastomer in the total mass of the liquid metal-polymer elastomer encapsulation layer is 30%-50%.

[0035] In a preferred embodiment, the percentage of liquid metal in the total mass of the liquid metal-polymer elastomer encapsulation layer is 55%-65%. Specifically, the percentage of liquid metal in the total mass of the liquid metal-polymer elastomer encapsulation layer is 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69% or 70%, any one of the values ​​or a range consisting of any two values.

[0036] When the percentage of liquid metal in the total mass of the liquid metal-polymer elastomer encapsulation layer is 50%-70%, the best capacitance performance under the same strain can be achieved; when the percentage of liquid metal in the total mass of the liquid metal-polymer elastomer encapsulation layer is less than 50%, poor capacitance performance under the same strain will result; when the percentage of liquid metal in the total mass of the liquid metal-polymer elastomer encapsulation layer is greater than 70%, poor material stability will result.

[0037] In a preferred embodiment, the percentage of the polymer elastomer in the total mass of the liquid metal-polymer elastomer encapsulation layer is 35%-45%. Specifically, the percentage of the polymer elastomer in the total mass of the liquid metal-polymer elastomer encapsulation layer is 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49% or 50%, any one of the values ​​or a range consisting of any two values.

[0038] When the percentage of polymer elastomer in the total mass of the liquid metal-polymer elastomer encapsulation layer is 30%-50%, better material stability can be achieved; when the percentage of polymer elastomer in the total mass of the liquid metal-polymer elastomer encapsulation layer is less than 30%, the product will be insufficiently flexible; when the percentage of polymer elastomer in the total mass of the liquid metal-polymer elastomer encapsulation layer is greater than 50%, the product will be too flexible.

[0039] In one embodiment, the liquid metal includes a gallium-indium eutectic alloy, wherein the total mass of the gallium-indium eutectic alloy is 100%, the percentage of gallium element in the total mass of the gallium-indium eutectic alloy is 20%-30%; the percentage of indium element in the total mass of the gallium-indium eutectic alloy is 70%-80%; the polymer elastomer includes one or more of polyimide, polydimethylsiloxane, and polylysine.

[0040] Specifically, gallium in gallium-indium eutectic alloy (EGaIn) can stably maintain liquid state over a wide temperature range; compared with other liquid metals, it has the characteristics of low toxicity, low vapor pressure, recyclability, and stable chemical properties. The melting point can be lowered by alloying with other metals. Gallium-based liquid materials are ideal materials for the next generation of wearable devices, soft robots, flexible and stretchable electronic products. The melting point of EGaIn is 15.7°C. Due to the significant supercooling effect, EGaIn is liquid above -19°C and has good thermal conductivity. The thermal conductivity of its alloy at room temperature is about 27 times that of water; by using gallium-indium eutectic alloy and polymer elastomer material, a composite packaging material with both high airtightness and excellent stretchability is formed.

[0041] In a preferred embodiment, the percentage of gallium element in the total mass of the gallium-indium eutectic alloy is 22%-28%. Specifically, the percentage of gallium element in the total mass of the gallium-indium eutectic alloy is any point value among 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30%, or a range value consisting of any two point values.

[0042] When the percentage of gallium element in the total mass of the gallium-indium eutectic alloy is 20%-30%, moderate yield strength and excellent elongation technical effects can be achieved; when the percentage of gallium element in the total mass of the gallium-indium eutectic alloy is less than 20%, the gallium-indium eutectic alloy will be insufficiently flexible; when the percentage of gallium element in the total mass of the gallium-indium eutectic alloy is greater than 30%, the gallium-indium eutectic alloy will be too soft.

[0043] By adjusting the ratio of gallium to indium in the gallium-indium eutectic alloy, the viscosity and surface tension of the gallium-indium eutectic alloy are optimized to meet different packaging requirements.

[0044] In a preferred embodiment, the percentage of indium element in the total mass of the gallium-indium eutectic alloy is 72%-78%. Specifically, the percentage of indium element in the total mass of the gallium-indium eutectic alloy is any point value among 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79% or 80%, or a range value consisting of any two point values.

[0045] When the percentage of indium element in the total mass of the gallium-indium eutectic alloy is 70%-80%, the technical effects of medium yield strength and excellent elongation can be achieved; when the percentage of indium element in the total mass of the gallium-indium eutectic alloy is less than 70%, the gallium-indium eutectic alloy will be too soft; when the percentage of indium element in the total mass of the gallium-indium eutectic alloy is greater than 80%, the gallium-indium eutectic alloy will lack flexibility.

[0046] In one embodiment, a communication module is further included, and an embedding groove is provided on the packaging material layer, and the communication module is embedded in the embedding groove.

[0047] The present invention provides an embedding groove on the packaging material layer and places a communication module in the embedding groove, thereby providing wireless connection capability for flexible electronic devices, broadening their application scenarios, and laying a solid foundation for the commercialization and wide application of flexible electronic devices.

[0048] In one embodiment, the length of the embedded groove ranges from 10 to 20 mm; the width of the embedded groove ranges from 10 to 20 mm.

[0049] In a preferred embodiment, the length range of the embedded groove is 12-18 mm. Specifically, the length range of the embedded groove is any point value among 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm or 20 mm, or a range value composed of any two point values.

[0050] In a preferred embodiment, the width range of the embedded groove is 12-18 mm. Specifically, the width range of the embedded groove is any point value among 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm or 20 mm, or a range value composed of any two point values.

[0051] The present invention also includes a communication module embedded in the embedding slot to realize the wireless communication function of the package substrate. Ensure that it meets the packaging requirements of high-performance electronic devices. Specifically, the communication module embedded in the embedding slot includes one or more of a wireless communication module supporting Bluetooth 5.0, a wireless communication module supporting Wi-Fi 6, and a wireless module supporting 5G communication.

[0052] The integration of wireless communication modules provides flexible electronic devices with wireless connection capabilities and broadens their application scenarios.

[0053] like Figure 1 As shown, in one embodiment, another aspect of the present invention provides a method for preparing a flexible packaging substrate, comprising the following steps: S1. Mixing the liquid metal and the polymer elastomer uniformly to prepare a composite material; S2. Laying the composite material on the substrate and forming a packaging material layer by high temperature hot pressing; S3. The multiple packaging material layers and the multiple insulation layers are alternately stacked in sequence, and conductive glue is coated between adjacent packaging material layers and insulation layers.

[0054] Specifically, in step S1, the liquid metal is a liquid metal gallium indium eutectic alloy (EGaIn), which remains liquid at room temperature and has good conductivity and stretchability.

[0055] High-purity gallium and indium raw materials are used to prepare the alloy through vacuum melting and precision casting technology. The alloy is prepared under the protection of inert gas to prevent oxidation; ensuring that the alloy purity reaches more than 99.99%.

[0056] The liquid metal and the polymer elastomer are mixed, and the two materials are fully mixed through mechanical stirring and ultrasonic dispersion technology to form a uniform composite material.

[0057] In step S3, the composite packaging material layers and the insulating layers are alternately stacked using automated lamination equipment, and the conductive adhesive is precisely patterned between each layer using laser direct writing technology to construct vertical interconnections; alternatively, the conductive adhesive is precisely patterned using an automatic dispensing system to construct vertical interconnections between layers; an automatic dispensing machine and ultraviolet curing process may also be used to achieve precise patterning and rapid curing of the conductive adhesive between layers.

[0058] The electrical connection of the multi-layer packaging structure and the stable operation of the communication module are ensured by automated lamination technology and laser direct writing patterned conductive adhesive. These two innovations together constitute the core protection content of the present invention, which not only enhances the packaging performance of flexible electronic devices, but also expands its application potential in high-end application fields such as wearable devices and flexible display screens.

[0059] Afterwards, use an 800-2000 mesh precision polishing machine to polish the surface of the package substrate to remove surface burrs to obtain a smoother surface; The package substrate can also be chemically cleaned with a mixed solution of acetone and isopropyl alcohol to remove residues; Finally, the chemical properties of the surface of the packaging substrate are changed by plasma surface treatment to increase the surface energy; alternatively, the surface of the packaging substrate is treated by oxygen plasma surface treatment to increase the surface energy and enhance the bonding strength of the subsequent bonding process; a thin silver layer can also be formed on the surface of the packaging substrate by chemical plating technology to improve its conductivity and reflectivity.

[0060] The processing method of the present invention not only ensures high performance, but also takes into account cost-effectiveness and process compatibility, which helps to promote the industrialization process of flexible electronic technology and provides a new technical approach for the design and manufacture of flexible electronic devices.

[0061] In one embodiment, in step S2, "laying the composite material on the substrate and forming a packaging material layer by high temperature hot pressing" includes the following steps: S21. A plurality of glass balls are disposed on the surface of the substrate; S22. Roll the composite material multiple times to form a uniform liquid metal-polymer elastomer encapsulation layer, lay the liquid metal-polymer elastomer encapsulation layer on the glass ball, and form an encapsulation material layer by a laminator at 100-160°C and a pressure of 5-10MPa; or, directly cast the composite material on the glass ball; and cure it by a hot pressing process at 120-180°C and a pressure of 1-5MPa for 0.5-2h to form an encapsulation material layer.

[0062] In step S21 , micron-sized glass balls are grown on a substrate by chemical vapor deposition (CVD) technology. The construction of the micron-sized glass ball array is completed in a precisely controlled CVD device to ensure the uniformity and accuracy of the array.

[0063] In step S22, the composite material is rolled multiple times to form a uniform liquid metal-polymer elastomer encapsulation layer, the liquid metal-polymer elastomer encapsulation layer is laid on the micron glass ball array support, and a packaging material layer is formed by a laminator at 100-160°C and a pressure of 5-10MPa; Alternatively, the composite material is directly cast on the glass ball array layer; cured by a hot pressing process at 120-180°C and 1-5MPa pressure for 0.5-2h, and the thickness of the cured composite packaging material layer is controlled to be 0.5-1.5mm; and a packaging material layer is formed, which has good mechanical strength and flexibility.

[0064] In one embodiment, before “alternating and stacking the multiple packaging material layers and the multiple insulation layers in sequence”, the following steps are also included: S31. An embedding groove is provided on the packaging material layer, and the communication module is embedded in the embedding groove; S32. Fill the gap between the communication module and the corresponding embedded slot with conductive glue and sealant; In step S31, an embedding groove is provided at the end of the packaging material layer, the thickness of the packaging material layer is 0.3mm; the thickness of the embedding groove is 0.1mm; a communication module is placed in the embedding groove, and then the communication module is fixed in the embedding groove by precise micro-welding technology, and sealed with conductive glue to ensure the electrical connection between the communication module and the packaging material layer, so as to realize the wireless communication function of the packaging substrate, and ensure that it meets the packaging requirements of high-performance electronic devices.

[0065] In step S32, the conductive adhesive includes one or more of 3620FA conductive adhesive, 8880 conductive adhesive and 8890 conductive adhesive; and the sealant includes epoxy molding.

[0066] Specifically, the conductive adhesive contains one or more of Au, Ag and Cu, which can provide better conductivity compared to other conductive materials.

[0067] In some examples, using one or more conductive adhesives selected from 3620FA conductive adhesive, 8880 conductive adhesive, and 8890 conductive adhesive can better bond the outer wall of the communication module to the inner wall of the embedding slot compared to using other conductive adhesives, thereby ensuring the firmness of the connection between the communication module and the embedding slot.

[0068] Specifically, the sealant has the function of isolating water vapor, thereby achieving the effect of protecting the communication module and the substrate circuit.

[0069] The beneficial effects of the present invention are further illustrated below in conjunction with embodiments.

[0070] In order to make the invention purpose, technical scheme and beneficial technical effect of the present invention clearer, the present invention is further described in detail below in conjunction with examples. However, it should be understood that the examples of the present invention are only for explaining the present invention, not for limiting the present invention, and the examples of the present invention are not limited to the examples given in the specification. The specific experimental conditions or operating conditions not specified in the examples are made under conventional conditions, or are made under the conditions recommended by the material supplier.

[0071] In addition, it should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before or after the combination step or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified; it should also be understood that the combination connection relationship between one or more devices / apparatuses mentioned in the present invention does not exclude the existence of other devices / apparatuses before or after the combination device / apparatus or the insertion of other devices / apparatuses between these explicitly mentioned two devices / apparatuses, unless otherwise specified. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or the scope of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the present invention without substantially changing the technical content.

[0072] In the following examples, the reagents, materials and instruments used, unless otherwise specified, can be purchased commercially or obtained by synthetic methods known in the art.

[0073] Implementation 1: This embodiment is used to illustrate the method for preparing the flexible packaging substrate disclosed in the present invention; it includes detailed parameters and expected results; and specifically includes the following steps: S1. Preparation of liquid metal substrate: Using high-purity gallium and indium raw materials, the gallium-indium eutectic alloy (EGaIn) is prepared through vacuum melting technology to ensure that the alloy purity reaches more than 99.99%.

[0074] S2. Compounding of Elastomer Materials: Polyimide (PI) and EGaIn alloy are mixed in a mass ratio of 1:1, and the two materials are fully mixed in a solvent by mechanical stirring and ultrasonic dispersion technology to form a uniform composite material.

[0075] S3. Construction of micron glass sphere array support: Micron-sized glass spheres with a diameter of 15 microns are grown on a silicon substrate using chemical vapor deposition (CVD) technology, and the spacing between the spheres is controlled at 20 microns.

[0076] The micron glass sphere arrays are fabricated in a precisely controlled CVD device to ensure uniformity and accuracy of the array.

[0077] S4. Molding of composite packaging materials: The composite material was poured onto a micron glass ball array support and cured using a hot press at 120°C and a pressure of 5 MPa for 30 minutes; the thickness of the composite encapsulation material layer after curing was controlled to be 1 mm.

[0078] S5. Embedding of wireless communication module: An embedding groove with a size of 10 mm × 10 mm is reserved in the composite packaging material layer. The wireless communication module supporting Bluetooth 5.0 is fixed in the groove using micro-welding technology and sealed with conductive glue to ensure the electrical connection between the module and the packaging material layer. S6. Construction of multi-layer packaging structure: Automated lamination equipment is used to alternately stack composite packaging material layers and insulating layers to form a 5-layer structure; laser direct writing technology is used to achieve precise patterning of conductive adhesive between the 5 layers to build vertical interconnections.

[0079] S7. Post-processing of packaging substrate: The formed multi-layer packaging substrate is precision-polished to 800 mesh to remove surface burrs; a mixed solution of acetone and isopropyl alcohol is used for chemical cleaning to remove residues; plasma surface treatment is used to change the chemical properties of the material surface and increase the surface energy.

[0080] S8. Performance test: The gas tightness test was performed using a helium mass spectrometer with a detection limit of 10 -8 Pa·m3 / s, no leakage was detected on the package substrate.

[0081] The electronic tensile testing machine conducted a tensile test and found that the package substrate did not break under 200% tensile deformation.

[0082] Use high-precision LCR meter to test electrical performance, insulation resistance reaches 10 12 Ohm meter, meeting high insulation requirements.

[0083] The signal strength and communication distance of the wireless communication module were tested. The module communicated stably within a range of 10 meters, and the signal strength was -60 dBm.

[0084] S9. Package application verification: The packaging substrate was applied to the packaging of a flexible display screen. After 1,000 bending tests, the display screen worked normally and there was no packaging failure.

[0085] In extreme temperature (-40°C to 85°C) cycle tests, the packaging substrate maintained good performance stability.

[0086] Through the above embodiments, the flexible packaging substrate processing method of the present invention successfully prepares a new type of flexible packaging substrate, which can provide excellent electrical performance and environmental sealing performance while maintaining the necessary mechanical flexibility. In addition, the integrated wireless communication module further expands the function of the packaging substrate, enabling it to meet the packaging requirements of high-end flexible electronic devices.

[0087] Implementation 2: In this embodiment, the flexible packaging substrate processing method of the present invention further optimizes the material selection and process flow to meet a wider range of application requirements. The following are detailed parameters and results, as well as clear processes and steps.

[0088] S1. Substrate pretreatment: Polyethylene terephthalate (PET) was selected as the substrate material, and the substrate was pre-dried in an oven at 40°C to remove surface moisture.

[0089] S2. Composite of liquid metal and polymer elastomer: The liquid metal EGaIn alloy is ultrasonically cleaned to remove surface oxides; - EGaIn and polyimide (PI) elastomer are mixed in a mass ratio of 3:2 and rolled multiple times on a three-roll mill to form a uniform composite tape.

[0090] S3. Preparation of micron glass sphere array: Micron glass ball arrays were prepared on a PET substrate using photolithography and plasma etching techniques. The diameter of the spheres was 20 microns and the spacing was 25 microns.

[0091] S4. Lamination of composite packaging materials: The composite tape was laid on a micron glass ball array support and laminated by a laminator at 130° C. and a pressure of 7 MPa to form a packaging material layer with a thickness of 0.8 mm.

[0092] S5. Integration of wireless communication module: An embedding groove with a size of 15 mm × 15 mm is reserved in the packaging material layer for placing the wireless communication module supporting Wi-Fi 6.

[0093] Micro-welding is performed using an automated welding robot to ensure precise connections between the module and the packaging material layer.

[0094] S6. Construction of multi-layer packaging structure: Automated lamination equipment is used to alternately stack 5 layers of composite packaging material and 4 layers of insulating PET to form a 9-layer structure; the automatic dispensing system is used to achieve precise patterning of the conductive adhesive to build vertical interconnections between layers.

[0095] S7. Fine post-processing of packaging substrate: The surface of the package substrate is polished using a 1200 mesh precision grinder to ensure that the surface roughness reaches RS < 0.1 micron; oxygen plasma surface treatment is performed to increase the surface energy and enhance the bonding strength of the subsequent bonding process.

[0096] S8. Comprehensive performance test: The airtightness test shows that the helium leakage rate of the package substrate is less than 10 -9 Pa·m3 / s, meeting high air tightness requirements.

[0097] The tensile test showed that the packaging substrate did not break under 300% tensile deformation, showing excellent flexibility.

[0098] The electrical performance test results show that the insulation resistance exceeds 10 13 Ohm·meter, the resistance stability of the conductive glue is good.

[0099] The signal strength test result of the wireless communication module is -50 decibel milliwatts, and the communication distance reaches 20 meters, meeting the requirements of high-performance communication.

[0100] S9. Packaging application and reliability verification: - The packaging substrate was applied to the packaging of a flexible wearable device. After 500 bending cycles, the device worked normally and the packaging was not damaged.

[0101] - In an accelerated aging test simulating actual use environments, the package substrate was kept at 85°C and 85% relative humidity for 1,000 hours without showing any performance degradation.

[0102] Through this embodiment, the flexible packaging substrate processing method of the present invention demonstrates its applicability and reliability under different materials and process conditions. The optimized processing flow not only improves the performance of the packaging substrate, but also enhances its stability and durability in practical applications. In addition, the integrated high-performance wireless communication module further expands the application scope of the packaging substrate, enabling it to meet the needs of more high-end flexible electronic devices. Specific implementation 3: In this embodiment, the flexible packaging substrate processing method of the present invention is specially optimized for a specific flexible solar cell application. The following are detailed parameters, steps and expected results.

[0104] S1. Selection of substrate materials: Lightweight and highly transparent polyethylene terephthalate (PET) film is selected as the main material of the encapsulation substrate to ensure the photoelectric conversion efficiency of solar cells.

[0105] S2. Surface treatment of liquid metal substrate: - Surface passivation of liquid metal gallium indium eutectic alloy (EGaIn) to prevent oxidation during processing.

[0106] S3. Composite of elastomer and liquid metal: The EGaIn alloy and the polyimide (PI) elastomer were mixed in a mass ratio of 2:3 and melt-blended by a blending extruder to form a uniform composite.

[0107] S4. Preparation of micron glass sphere arrays: Using template-assisted self-assembly technology, a micron glass sphere array was formed on a PET substrate, with a sphere diameter of 30 microns and a spacing of 30 microns.

[0108] S5. Molding of packaging materials: The composite was cast on the micron glass ball array and cured by a hot press process at 150 °C and 3 MPa pressure for 1 hour to form an encapsulation material layer with a thickness of 1 mm.

[0109] S6. Integration of wireless communication module: An embedding groove with a size of 20 mm × 20 mm is reserved in the packaging material layer for placing the wireless module supporting 5G communication.

[0110] The wireless module is fixed in the slot using precision automated placement technology and sealed with conductive adhesive.

[0111] S7. Construction of multi-layer packaging structure: A lamination process is used to alternately stack 7 layers of composite packaging material and 6 layers of PET insulation layers to form a 13-layer multi-layer packaging structure.

[0112] Use an automatic dispenser and UV curing process to achieve precise patterning and rapid curing of interlayer conductive adhesive.

[0113] S8. Post-processing of packaging substrate: The surface of the package substrate is polished using a 2000-mesh precision polishing machine to obtain a smoother surface.

[0114] A thin layer of silver is formed on the surface of the package substrate through chemical plating technology to improve its conductivity and reflectivity.

[0115] S9. Performance test: The airtightness test shows that the helium leakage rate of the package substrate is less than 10 -10 Pa·m3 / s, meeting the high airtightness requirements of solar cell packaging.

[0116] Tensile tests showed that the package substrate showed no cracks or delamination after 500 repeated bends (bending radius of 3 mm).

[0117] The electrical performance test results show that the surface resistivity of the package substrate is less than 10 -4 Ohm / square, which is beneficial to the photoelectric conversion of solar cells.

[0118] The signal strength test result of the wireless communication module is -40 decibel milliwatts, and the communication distance reaches 30 meters, meeting the 5G communication requirements.

[0119] S10. Packaging application and reliability verification: The packaging substrate is used for the packaging of flexible solar cells. After 200 hours of outdoor field testing, the performance of the solar cells protected by the packaging substrate is stable and the photoelectric conversion efficiency has not decreased.

[0120] In the UV aging test under simulated outdoor environment, the package substrate showed no obvious yellowing or performance degradation after 1000 hours of UV irradiation.

[0121] Through this embodiment, the flexible packaging substrate processing method of the present invention demonstrates its application potential in the field of solar cell packaging. The optimized processing flow not only improves the photoelectric conversion efficiency and airtightness of the packaging substrate, but also enhances its stability and durability in outdoor environments. In addition, the integrated 5G wireless communication module makes it possible to intelligentize and remotely monitor the solar cell system.

[0122] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A flexible packaging substrate, characterized in that: It comprises packaging material layers and insulating layers which are alternately stacked in sequence; the packaging material layers comprise a liquid metal-polymer elastomer packaging layer and a substrate, the liquid metal-polymer elastomer packaging layer is arranged on the surface of the substrate, and the liquid metal-polymer elastomer packaging layer comprises liquid metal and polymer elastomer mixed with each other.

2. The flexible packaging substrate according to claim 1, characterized in that: The insulating layer includes a die-bonding adhesive; the thickness of the insulating layer is 10-25 um, and / or The substrate includes one or more of a silicon substrate and polyethylene terephthalate; the thickness of the substrate is 50-150 um.

3. The flexible packaging substrate according to claim 1, characterized in that: A plurality of glass balls are arranged on the surface of the substrate, and the glass balls are embedded in the liquid metal-polymer elastomer encapsulation layer; the diameter of the glass balls is 10-30 μm; and the distance between two adjacent glass balls is 10-30 μm.

4. The flexible packaging substrate according to claim 1, characterized in that: Taking the total mass of the liquid metal-polymer elastomer encapsulation layer as 100%, the percentage of the liquid metal in the total mass of the liquid metal-polymer elastomer encapsulation layer is 50%-70%; the percentage of the polymer elastomer in the total mass of the liquid metal-polymer elastomer encapsulation layer is 30%-50%.

5. The flexible packaging substrate according to claim 4, characterized in that: The liquid metal includes a gallium-indium eutectic alloy, and based on the total mass of the gallium-indium eutectic alloy being 100%, the percentage of gallium element in the total mass of the gallium-indium eutectic alloy is 20%-30%; the percentage of indium element in the total mass of the gallium-indium eutectic alloy is 70%-80%; the polymer elastomer includes one or more of polyimide, polydimethylsiloxane, and polylysine.

6. The flexible packaging substrate according to claim 1, characterized in that: A communication module is also included. An embedding groove is provided on the packaging material layer, and the communication module is embedded in the embedding groove.

7. The flexible packaging substrate according to claim 1, characterized in that: A conductive pattern is arranged between the packaging material layer and the insulating layer.

8. The method for preparing a flexible packaging substrate according to any one of claims 1 to 7, characterized in that: The following steps are involved: The liquid metal and the polymer elastomer are mixed evenly to prepare a composite material; Laying the composite material on the substrate and forming a packaging material layer by high temperature hot pressing; The multiple packaging material layers and the multiple insulation layers are alternately stacked in sequence, and conductive patterns are arranged between adjacent packaging material layers and insulation layers.

9. The method for preparing a flexible packaging substrate according to claim 8, characterized in that: The step of "laying the composite material on the substrate and forming a packaging material layer by high temperature hot pressing" includes the following steps: A plurality of glass balls are arranged on the surface of the substrate; The composite material is rolled multiple times to form a uniform liquid metal-polymer elastomer encapsulation layer, the liquid metal-polymer elastomer encapsulation layer is laid on a glass ball, and a laminator is used to form an encapsulation material layer at 100-160°C and a pressure of 5-10MPa; or, the composite material is directly poured on the glass ball; and cured for 0.5-2h at 120-180°C and a pressure of 1-5MPa through a hot pressing process to form an encapsulation material layer.

10. The method for preparing a flexible packaging substrate according to claim 8, characterized in that: Before the step of "alternatingly stacking the multiple packaging material layers and the multiple insulation layers in sequence", the following steps are also included: An embedding groove is provided on the packaging material layer, and the communication module is embedded in the embedding groove; The gap between the communication module and the corresponding embedding groove is filled with conductive glue and sealant.

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