Liquid metal-based packaging structure, packaging method and package

Abstract

The application relates to a liquid metal-based packaging structure, a packaging method and a packaging body, the packaging structure comprising a first elastic layer and a second elastic layer; a containing cavity is formed between the first elastic layer and the second elastic layer, and a liquid metal fills the containing cavity to form an intermediate liquid metal layer; the filling amount Q of the liquid metal satisfies Q=N*S, wherein Q is the filling amount of the liquid metal, the unit is g; S is a packaging area, the unit is cm 2 ; and the value of N is 5*10 ‑6 -2 g / cm 2 . By filling an appropriate amount of liquid metal in the containing cavity formed by the two elastic layers, a packaging structure with excellent barrier performance and flexibility can be formed. Based on the packaging structure design, the application further provides a packaging method, which can package various structures and sizes of objects to be packaged, thereby providing a long-term stable packaging body and widening the application space of the packaging material.

Description

Technical Field

[0001] This invention belongs to the field of packaging technology, and particularly relates to a packaging structure, packaging method and packaging body based on liquid metal. Background Technology

[0002] Sealed packaging is ubiquitous in industrial production and daily life, especially for highly sensitive, high-value-added electronic devices. The importance of sealed packaging is well-known. Traditional rigid electronic devices are designed to be encased in packaging materials to keep reactive gases (such as oxygen and water) away from the sensitive materials, thus ensuring the long-term stability of the device. However, with technological advancements and the continuous improvement of people's living standards and demands, rigid electronic devices can no longer meet diverse and changing needs, leading to the emergence of flexible and stretchable devices. Flexible and stretchable electronics technology, based on flexible materials, using flexible electronic devices as a platform, and incorporating optoelectronic technology applications, is a disruptive science and technology formed on the basis of a high degree of interdisciplinary integration of physics, chemistry, materials science and engineering, optical engineering, and biomedical engineering. Compared to traditional electronic devices, flexible and stretchable electronic devices have greater flexibility and can adapt to different working environments to a certain extent, meeting the deformation requirements of equipment.

[0003] The inherent characteristics and applications of stretchable and flexible devices place certain requirements on the Young's modulus of the encapsulation material, limiting the selection to low-modulus materials. Elastomers composed of cross-linked polymer chains are frequently used encapsulation materials in this field, providing secure external protection and elastic load-bearing capacity. However, they possess a large unfilled volume at the microscopic level, and the polymer chains within them are highly mobile, allowing reactive gases (such as oxygen and water) to easily permeate, leading to damage to stretchable and flexible devices. In existing technologies, the lifespan of stretchable and flexible devices sensitive to reactive gases is significantly shorter than that of comparable rigid devices.

[0004] Current research generally agrees that low-modulus materials have high gas permeability, and no material possesses both low modulus and low gas permeability exists. Therefore, methods to address the challenges of stretchable packaging technology mainly focus on combining low Young's modulus materials with high gas permeability (e.g., elastomers) with high Young's modulus materials with low gas permeability (e.g., inorganic or metallic materials). Patent CN111373840B provides a method for manufacturing an electronic device with an organic thin film that functions as a sealing film for moisture permeability in electronic devices such as organic electroluminescent elements. This method for manufacturing an electronic device comprises at least an organic functional layer, an anti-leaching film, and a sealing film in sequence, and includes the steps of: coating an organosilicon resin and then irradiating it with vacuum ultraviolet light to form the anti-leaching film; and coating a mixture of a metal alkoxide and a fluoroalcohol onto the anti-leaching film and then irradiating it with vacuum ultraviolet light to form the sealing film. By performing surface treatment on the silicone resin of the anti-leaching film using vacuum ultraviolet light, the surface composition changes to SiO2, increasing the affinity for inorganic oxides and significantly improving the adhesion to sealing films containing organometallic oxides. Patent application CN105848882A discloses a metal encapsulation material with excellent heat dissipation, its preparation method, and a flexible electronic device encapsulated using the said metal encapsulation material. It forms a coating containing a metal-graphite composite on one side, thus providing a metal encapsulation material with excellent flexibility, moisture resistance, processability, and heat dissipation, as well as a flexible electronic device encapsulated using the said metal encapsulation material. Although the above invention can achieve good encapsulation performance under static or certain tensile conditions, because its coating uses a rigid material, when the tension exceeds the coating's tolerance, external force damage will irreversibly lead to the loss of encapsulation performance.

[0005] It is evident that most existing organic-inorganic composite encapsulation materials, aside from their inherently limited resistance to tensile and bending forces, should not be considered flexible encapsulation materials. Furthermore, significant damage may occur at the microscopic level; even if they exhibit some flexibility and stretchability macroscopically, their sealing performance cannot be guaranteed under external forces and may even be severely compromised.

[0006] Providing flexible and stretchable materials suitable for encapsulating flexible electronic devices to extend device lifespan and fill the gaps in flexible packaging technology is urgently needed. Liquid metal, as the only material possessing both metallic and fluid properties, has an effective Young's modulus close to zero, offering new opportunities for flexible and stretchable packaging technology. As metals, aluminum and steel have excellent gas barrier properties and are widely used in sealed packaging, such as the linings of canned foods and potato chip bags in the food industry. However, metals are generally non-stretchable. Liquid metal, due to its fluid properties, is an exception. Currently, liquid metals are attracting increasing attention from the research community: their metallic conductivity and fluid deformability make them suitable for use in stretchable, flexible devices; their metallic thermal conductivity and fluid deformability also offer the potential to use them as thermal interface materials for efficient heat dissipation in electronic devices. However, the hermeticity of liquid metals and their application in the encapsulation of stretchable, flexible devices have received little research.

[0007] Therefore, designing a packaging material and packaging method based on liquid metal that can simultaneously achieve low Young's modulus and low gas-liquid permeability is an urgent problem to be solved. Summary of the Invention

[0008] The purpose of this invention is to provide a liquid metal-based encapsulation material, an encapsulation method based on the encapsulation material, and an encapsulated body obtained by the encapsulation method, in order to solve the technical problem that existing encapsulation materials cannot simultaneously achieve low Young's modulus and low gas-liquid permeability.

[0009] Specifically, this invention provides a liquid metal-based encapsulation structure, including a first elastic layer and a second elastic layer; a cavity is formed between the first and second elastic layers, and liquid metal fills the cavity to form an intermediate liquid metal layer; the amount of liquid metal Q satisfies: Q = N × S, where Q is the amount of liquid metal filled in grams (g); and S is the encapsulation area in centimeters. 2 The value of N is 5 × 10. -6 -2g / cm 2 .

[0010] This invention utilizes the inherent fluidity and low gas-liquid permeability of liquid metal to combine it with an elastic layer, resulting in a unique encapsulation structure suitable for flexible packaging applications subject to frequent deformation. Simultaneously, the liquid metal exhibits certain adhesion and hysteresis, providing the encapsulation structure with a degree of resistance to deformation. Through theoretical calculations and experimental testing, when N is set to 5 × 10⁻⁶... -6 -2g / cm 2 This allows the amount and average thickness of the liquid metal layer per unit area to meet the hermeticity requirements of most flexible devices, and the amount of liquid metal can be adjusted according to the application scenario and requirements, balancing performance and cost. When N is less than 5 × 10⁻⁶... -6g / cm 2 When the average thickness of the corresponding liquid metal layer is too low, "flow interruption" is very likely to occur during transportation and use, leading to encapsulation failure; when the value of N is greater than 2 g / cm³... 2 At present, the average thickness of the liquid metal layer is relatively large. Although this is beneficial to the improvement of packaging performance, the excessive weight of the liquid metal layer can easily lead to increased stress on the elastomer bonding area, resulting in damage and leakage. Furthermore, the overall weight of the packaging structure is significantly increased, reducing the ease of application at each stage, and particularly increasing raw material and transportation costs. Considering factors such as the stretching range and cost of commonly used flexible devices, this invention selects the above-mentioned liquid metal filling amount to meet the needs of most application scenarios.

[0011] Furthermore, the first elastic layer and / or the second elastic layer are selected from at least one of natural rubber layer, synthetic rubber layer, ionogel layer, and hydrogel layer; the liquid metal is selected from at least one of gallium-based liquid metal, indium-based liquid metal, and bismuth-based liquid metal.

[0012] Existing technologies commonly employ airtight methods such as aluminum plating and tin plating (e.g., aluminum foil and tin foil), which utilize the excellent barrier properties of metal layers. However, they cannot avoid the solidity and rigidity of metals, leading to defects such as the inability to stretch the package or a sharp decrease in airtightness after stretching. The use of a liquid metal layer in this invention fully leverages the dual metallic and room-temperature fluid properties of liquid metals, effectively overcoming the technical obstacles of existing technologies that struggle to simultaneously achieve both sealing and stretchability. This provides a new approach and direction for the packaging of flexible devices.

[0013] Furthermore, the value of N ranges from 0.05 to 0.8 g / cm³. 2 Based on the structure and dimensions of commonly used packaging materials in the prior art, this invention further designs a more universal liquid metal content per unit area. The liquid metal filling amount can be easily calculated using the N value, and the thickness of the liquid metal layer can also be roughly estimated.

[0014] Furthermore, on the surface of the first elastic layer facing the second elastic layer, and / or the surface of the second elastic layer facing the first elastic layer, there are several protrusions integrally formed with the elastic layers. The height of the protrusions is 0.05-1mm, the spacing between adjacent protrusions is 0.01-5mm, and the surface of the protrusions has a gas barrier layer. Based on the high-performance encapsulation structure obtained by combining elastic layers with liquid metal, it is necessary to consider the problem of losing the advantages of liquid metal and reducing barrier performance by minimizing contact between the elastic layers. On the one hand, an ideal liquid metal filling amount can be calculated to design an effective filling amount considering deformation under various application scenarios, such as external forces such as compression, stretching, and bending. On the other hand, it is also possible to design the opposing surfaces of the elastic layers so that even if the elastic layers contact each other, their area is as small as possible. For example, several protrusions can be provided on the surface of the first elastic layer facing the second elastic layer, and / or the surface of the second elastic layer facing the first elastic layer. This can prevent the two elastic layers from becoming too close or even adhering together due to gravity, pressure, deformation, etc., making them impossible to separate. Furthermore, the support provided by the protrusions themselves enables the overall packaging structure to resist excessive deformation to a certain extent. The height of the protrusions ensures sufficient space between the two elastic layers to prevent them from sticking together and provides space for liquid metal filling. The spacing of the protrusions ensures that they are not too sparse to provide support. A gas barrier layer is provided on the top surface of the protrusions to prevent the hermeticity from decreasing when the two elastic layers are in direct contact. More preferably, a gas barrier layer with a thickness of about 0.001-0.5 mm is also formed on the protrusions, so that even if the two elastic layers are continuously stuck together by external forces, the gas barrier layer can still exhibit good barrier performance, thereby avoiding packaging failure. Moreover, since the protrusions are not continuously arranged, the gas barrier layer at the top is also discontinuous. When subjected to external forces, the top part is less damaged by tensile, bending, and other external forces, has strong structural integrity, and relatively stable barrier performance.

[0015] Secondly, based on the aforementioned packaging structure, the present invention also provides a packaging method, comprising the following steps:

[0016] Step 1: Surround and seal the object to be packaged with a second elastic layer to form an inner packaging structure;

[0017] Step 2: Surround and seal the second elastic layer with the first elastic layer to form an outer encapsulation structure; a receiving cavity is formed between the first elastic layer and the second elastic layer;

[0018] Step 3: Fill the cavity with liquid metal through the liquid metal inlet reserved on the first elastic layer to form an intermediate liquid metal layer.

[0019] This encapsulation method is simple and easy to operate. It not only allows liquid metal to completely encapsulate the object to be encapsulated, achieving both flexibility and airtightness, but also saves on processes and materials.

[0020] Furthermore, the process of filling the cavity with liquid metal includes the following steps:

[0021] S1: Cover the liquid metal inlet on the first elastic layer with liquid metal, and then place the entire outer packaging structure into a sealed container;

[0022] S2: Evacuate the sealed container to remove air from the sealed container and the cavity.

[0023] S3: Break the vacuum in the sealed container; liquid metal fills the cavity using the internal and external pressure difference;

[0024] S4: Remove the sealed container and seal the liquid metal inlet.

[0025] Compared to methods such as atmospheric pressure filling and pressurized filling, vacuum filling allows liquid metal to fill the space between the two elastomers as much as possible, reducing air residue and improving the hermeticity of the encapsulation structure. Vacuum filling can be divided into single-port vacuum filling or multi-port vacuum filling. In multi-port vacuum filling, a vacuum is created at a pre-reserved evacuation port, and a container holding liquid metal is connected to the liquid metal inlet. As the pressure in the receiving cavity decreases, the liquid metal enters from the outside and fills the cavity. However, this method results in multiple openings on the first elastic layer, making subsequent sealing cumbersome. Therefore, this invention provides a design that requires only one liquid metal inlet to achieve vacuum filling.

[0026] Specifically, regarding the method of covering the liquid metal inlet with liquid metal, preferably, in step S1, the liquid metal is placed in an open container with a through hole at the bottom. The through hole is aligned with the liquid metal inlet and sealed to form a liquid metal flow channel. This operation is simple, and the liquid metal will not flow freely and be lost or pollute the environment. Then, the outer packaging structure, the connected open container, and the liquid metal contained in the open container are placed together into a sealed container. The amount of liquid metal added can be roughly controlled by the amount added to the open container. The amount of liquid metal added to the open container must at least meet the requirements for filling volume and the remaining volume of the liquid metal flow channel (to minimize air mixing into the space containing the liquid metal, the liquid metal flow channel must always be covered by liquid metal). Therefore, observing and controlling the liquid level in the metal flow channel allows for a simple determination of the metal filling level.

[0027] Furthermore, an inner packaging structure can be formed by winding and bonding a single piece of the second elastic layer, or by bonding two pieces of the second elastic layer together. Similarly, an outer packaging structure can be formed by winding and bonding a single piece of the first elastic layer, or by bonding two pieces of the first elastic layer together. The selection of this inner and outer packaging structure forming method and the elastic layer bonding method can be based on factors such as the object to be packaged and the size of the elastic layer, minimizing the edges requiring sealing. This saves on processes and reduces the probability of sealing failure in the packaging structure.

[0028] Furthermore, prior to step one, several protrusions are integrally formed on the surface of the first elastic layer facing the second elastic layer, and / or on the surface of the second elastic layer facing the first elastic layer. The protrusions are then surface-treated, and an air-barrier layer is bonded to the surface-treated protrusions. This design reduces the contact area when contact between the shells is unavoidable during stress, and even if contact occurs, the pre-set air-barrier layer prevents direct contact between the shell's elastic layers, thus preventing a decrease in airtightness.

[0029] Thirdly, the present invention also provides a package prepared using the aforementioned encapsulation method, wherein the oxygen permeability of the package is 2.5 × 10⁻⁶ under a tensile condition of 5-20%. -6 cc / day / cm 2 Below, the water vapor transmission rate is 8.0 × 10⁻⁶. - 7 cc / day / cm 2 the following.

[0030] This invention includes at least the following technical advantages:

[0031] (1) By fully utilizing the metallic and fluid properties of liquid metal and combining it with an elastic outer layer for encapsulation, a flexible, stretchable, and gas-tight layered composite structure and its encapsulation are obtained. The encapsulation can be well applied to various devices with flexible stretching requirements, such as stretchable systems with volatile liquids (including water and organic liquids) and stretchable systems for electronic components with high airtightness requirements.

[0032] (2) The present invention calculates and conducts corresponding experiments on the filling of liquid metal in the elastic interlayer to obtain a range of liquid metal filling amount that can meet the needs of most flexible packaging, and obtains a flexible and stretchable packaging structure more easily.

[0033] (3) The protrusion integrally formed with the elastomer can effectively support and disperse the pressure of the elastic layer, prevent the elastic layers from becoming unstable or coming into contact with each other due to excessive deformation, and prevent the single barrier of the elastic layer from occurring in a disguised form. This prevents sealing failure and ensures that the packaging system has both good stretchability and long-term stable sealing barrier performance, providing the possibility and simple packaging operation for sealing devices with large deformation. Attached Figure Description

[0034] The above and other objects, features, and advantages of exemplary embodiments of the present disclosure will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of the present disclosure are illustrated by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding parts, wherein:

[0035] Figure 1 This is a schematic diagram of the first embodiment of the packaging structure and package body of the present invention;

[0036] Figure 2 This is a schematic diagram of the second embodiment of the packaging structure and package body of the present invention;

[0037] Figure 3 This is a schematic diagram of the liquid metal filling process in the encapsulation method of the present invention;

[0038] Figure 4 Yes Figure 3 A schematic diagram of the cross-section along the AA cutting line.

[0039] Explanation of reference numerals in the attached drawings: 100, 100′ - encapsulation structure, 200, 200′ - encapsulation body, 1 - first elastic layer, 2 - second elastic layer, 3 - receiving cavity, 4 - intermediate liquid metal layer, 5 - protrusion, 6 - gas barrier layer, 7 - object to be encapsulated, 8 - inner encapsulation structure, 9 - outer encapsulation structure, 10 - liquid metal inlet, 11 - open container, 12 - through hole. Detailed Implementation

[0040] To better understand the technical solution of this invention, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments. Similar elements in different embodiments are referred to by related similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the invention. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to this application are not shown or described in the specification. This is to avoid obscuring the core parts of the invention with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0041] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0042] The serial numbers assigned to components in this article, such as "first" and "second," are used only to distinguish the objects being described and do not imply any order or technical meaning.

[0043] Liquid metals are metals that exist in a liquid phase at room temperature, thus exhibiting fluid properties such as fluidity, plasticity, wettability, and capillary action. Currently known liquid metals include Fr (francium), Cs (cesium), Rb (rubidium), Hg (mercury), and Ga (gallium). Furthermore, liquid alloys formed from liquid metals are frequently used in engineering practice, such as gallium-indium-tin alloys and gallium-indium alloys. In this invention, "liquid metal" is a broad concept, encompassing alloys formed from liquid metals. This invention utilizes liquid metals to form encapsulation structures, leveraging the fluidity (Young's modulus close to 0) and low gas-liquid permeability of liquid metals to achieve both flexibility and extremely low gas-liquid permeability in the encapsulation process.

[0044] In a first aspect, a liquid metal-based encapsulation structure (100, 100') includes a first elastic layer 1 and a second elastic layer 2; a receiving cavity 3 is formed between the first elastic layer 1 and the second elastic layer 2, and liquid metal fills the receiving cavity 3 to form an intermediate liquid metal layer 4; the filling amount Q of the liquid metal satisfies: Q = N × S, where Q is the liquid metal filling amount in grams (g); and S is the encapsulation area in centimeters. 2 The value of N is 5 × 10. -6-2g / cm 2 Preferred concentration: 0.05-0.8 g / cm³ 2 Through estimation, the N value is taken as 0.05-0.8 g / cm³. 2 When the value is set, the corresponding metal layer thickness is approximately 0.07mm-1.5mm. However, the thickness of liquid metal is not fixed and varies greatly depending on the shape of the containment space and the stress state. Therefore, this invention distinguishes the characteristics of the liquid metal layer by the filling amount.

[0045] The first elastic layer 1 and the second elastic layer 2 can be made of materials such as natural rubber, synthetic rubber, ionogel, or hydrogel. Specifically, the first elastic layer 1 and the second elastic layer 2 are made of SYLGARD material manufactured by Dow Chemical Company. TM Silicone rubbers based on polydimethylsiloxane (PDMS), such as 184, 182, 170, 160, 186, or 164, have a weight mixing ratio between the base component and the curing agent ranging from 1:1 to 100:1, preferably (5-15):1, and more preferably 10:1. The curing agent is SYLGARD manufactured by Dow Chemical Company. TM Curing agents in silicone rubber kits based on polydimethylsiloxane (PDMS), such as 184, 182, 170, 160, 186, or 164. Structurally, the thickness of the first elastic layer 1 is 0.001-10 mm, preferably 0.01-2 mm, more preferably 0.1-1 mm; the thickness of the second elastic layer 2 is 0.001-10 mm, preferably 0.01-5 mm, more preferably 0.1-2 mm; the specific thicknesses of the first and second elastic layers can be selected and adjusted according to the actual encapsulation shape, size, and application environment. Comparatively, it is preferable that the thickness of the second elastic layer 2 is greater than or equal to the thickness of the first elastic layer 1.

[0046] The liquid metal is selected from at least one of the following: gallium, gallium-indium alloy, gallium-aluminum alloy, gallium-zinc-gold alloy, gallium-silver alloy, gallium-indium-tin alloy, gallium-indium-tin-zinc alloy, or other gallium-based liquid metals; or indium-bismuth alloy, indium-tin alloy, indium-tin-bismuth alloy, bismuth-lead-tin-cadmium alloy, bismuth-lead-tin-cadmium alloy, bismuth-lead-tin-cadmium-indium alloy, etc., which are liquid and have metallic bonds. Specifically, the liquid metal can be a eutectic gallium-indium alloy, wherein the gallium content is 70-80 wt%, such as 75.5 wt%; and the indium content is 20-30 wt%, such as 24.5 wt%.

[0047] The present invention proposes a second embodiment, in order to Figure 2 For example, on the surface of the first elastic layer 1 facing the second elastic layer 2, and / or on the surface of the second elastic layer 2 facing the first elastic layer 1, there are a plurality of protrusions 5 integrally formed with the elastic layer. The height of the protrusions 5 is 0.05-1mm, the spacing between adjacent protrusions 5 is 0.01-5mm, and the surface of the protrusions 5 has an air barrier layer 6.

[0048] Integrated molding technology is a commonly used technique in this field, such as injection molding, compression molding, casting, and etching. The advantage of integrated molding lies in the overall continuity of the components, eliminating the need for bonding or other methods, resulting in a uniform structural composition and superior mechanical properties. When the encapsulation structure 100' deforms (bending, twisting, stretching, etc.), the protrusion 5 prevents the first elastic layer 1 and the second elastic layer 2, which have high gas permeability, from adhering to each other over a large area, thereby preventing a decrease in the hermeticity of the encapsulation structure 100'. Simultaneously, the protrusion 5 helps the encapsulation structure 100' resist most of the deformation pressure, preventing instability and failure. The height of the protrusion 5 is 0.05-1mm, and the spacing between adjacent protrusions 5 is 0.01-5mm. The shape of the protrusion 5 can be selected from three-dimensional forms such as cylinders, frustums, cones, prisms, frustums, and pyramids, as well as combinations thereof.

[0049] To further reduce gas permeability, preferably, a gas barrier layer 6 is formed on the surface of the protrusion 5, preferably the top surface, using processes such as evaporation, sputtering, electroplating, blade coating, coating, or chemical vapor deposition. The gas barrier layer 6 is made of a low-permeability material, commonly used in the packaging field, and is selected from at least one of metals, inorganic non-metals, or composites thereof. Based on the primary purpose of the protrusion 5, under increased external force, the elastic layers approach each other, and the protrusion 5 acts as a supporting spacer between the two elastic bodies. The low permeability of the gas barrier layer 6 on the surface of the protrusion 5 and the low permeability of the liquid metal in the gap between the protrusions substantially increase the external force threshold for contact with the elastic layers. Specifically, copper can be bonded to the protrusion 5 using an adhesive or deposited by vapor deposition or electroplating; a plastic film with a gas barrier layer formed of copper, silicon oxide, aluminum oxide, etc. can be bonded to the protrusion 5 using an adhesive; an organic polymer material with high gas barrier properties (such as polyvinyl alcohol) can be spin-coated onto the protrusion 5; or an inorganic thin film (such as silicon oxide, aluminum oxide, etc.) or an organic film (such as poly(p-phenylene dimethyl)) with high gas barrier properties can be deposited onto the protrusion 5 under vacuum.

[0050] Before the gas barrier layer 6 is bonded to the protrusion 5, the protrusion 5 is preferably surface-treated to increase its bonding activity, including applying plasma, ultraviolet light, ozone, corona or chemical treatment or a combination thereof.

[0051] Secondly, the packaging method based on the packaging mechanism (100, 100') includes the following steps:

[0052] Step 1: Surround and seal the object to be packaged 7 with the second elastic layer 2 to form an inner packaging structure 8; wherein, the inner packaging structure 8 is formed by winding and bonding a single piece of the second elastic layer 2, or by butt-bonding and bonding multiple pieces of the second elastic layer 2 together.

[0053] Step 2: Surround and seal the second elastic layer 2 with the first elastic layer 1 to form an outer encapsulation structure 9; form a receiving cavity 3 between the first elastic layer 1 and the second elastic layer 2; form the outer encapsulation structure 9 by winding and bonding a single piece of the first elastic layer 1, or by butt-bonding and bonding multiple pieces of the first elastic layer 1 together.

[0054] Step 3: Fill the receiving cavity 3 with liquid metal through the liquid metal inlet 10 reserved on the first elastic layer 1 to form an intermediate liquid metal layer 4. The process of filling the receiving cavity 3 with liquid metal includes the following steps:

[0055] S3.1: Cover the liquid metal inlet 10 on the first elastic layer 1 with liquid metal, and then place the entire external encapsulation structure into a sealed container; specifically, place the liquid metal in an open container 11, the bottom of which has a through hole 12, the through hole 12 being aligned with and sealed with the liquid metal inlet 10 to form a liquid metal flow channel; that is, the liquid metal covers the liquid metal inlet 10 on the first elastic layer 1 in a manner that connects the metal flow channels, and then place the entire external encapsulation structure 9 and the open container 11 into the sealed container;

[0056] S3.2: Evacuate the sealed container to remove air from the sealed container and the receiving cavity 3;

[0057] S3.3: Break the vacuum in the sealed container; liquid metal fills the receiving cavity 3 using the internal and external pressure difference;

[0058] S3.4: Remove the sealed container and seal the liquid metal inlet 10.

[0059] Optionally, prior to step one, a plurality of protrusions 5 are integrally formed on the surface of the first elastic layer 1 facing the second elastic layer 2, and / or the surface of the second elastic layer 2 facing the first elastic layer 1, the protrusions 5 are surface treated, and then the gas barrier layer 6 is bonded to the surface-treated protrusions 5.

[0060] The encapsulation body (200, 200′) obtained by this invention has an oxygen permeability of 2.5 × 10⁻⁶ under a tensile condition of 5-20%. -6 cc / day / cm 2 Below, the water vapor transmission rate is 8.0 × 10⁻⁶. -7 cc / day / cm 2 the following.

[0061] Example 1

[0062] The packaging method of the package 200 in this embodiment specifically includes the following steps:

[0063] Step 1: Surround and seal the object to be packaged with the second elastic layer to form an inner packaging structure; wherein, the second elastic layer is a PDMS (model: Sylgard 184, Dow Chemical Company) inner layer with a thickness of 0.3mm;

[0064] Step 2: Surround and seal the second elastic layer with the first elastic layer to form an outer encapsulation structure; wherein, the first elastic layer is a PDMS outer layer with a thickness of 0.1mm;

[0065] Step 3: Liquid metal, specifically eutectic gallium-indium alloy (EGaIn) (Shenyang Jiabei Trading Co., Ltd.), is injected into the cavity between the inner and outer packaging structures through the pre-reserved liquid metal inlet on the first elastic layer to form an intermediate liquid metal layer. The amount of liquid metal used per unit area is 0.08 g / cm³. 2 The liquid metal inlet is sealed to obtain the encapsulated body.

[0066] The liquid metal is filled using a vacuum filling method, which specifically includes the following steps:

[0067] S3.1: Liquid metal is placed in an open container, the bottom of which has a through hole, which is aligned with the liquid metal inlet and sealed to form a liquid metal flow channel; the outer packaging structure and the open container are placed together in a sealed container;

[0068] S3.2: Evacuate the sealed container to remove air from the sealed container and the containing cavity;

[0069] S3.3: Break the vacuum in the sealed container; the liquid metal fills the cavity between the inner and outer packaging structures along the liquid metal flow channel using the pressure difference between the inside and outside;

[0070] S3.4: Remove the sealed container and seal the liquid metal inlet.

[0071] Accordingly, the resulting package comprises the following structural components:

[0072] Inner packaging structure: formed by a second elastic layer surrounding and sealing the object to be packaged; wherein the second elastic layer is a PDMS inner layer with a thickness of 0.3 mm;

[0073] Outer packaging structure: formed by a first elastic layer surrounding and sealing the inner packaging structure; wherein the first elastic layer is a PDMS outer layer with a thickness of 0.1 mm;

[0074] Intermediate liquid metal layer: formed by filling the remaining space between the inner and outer packaging structures with a liquid metal layer; the liquid metal is a eutectic gallium indium alloy (EGaIn), with a content of 0.08 g / cm². 2 .

[0075] Example 2

[0076] The main difference between this embodiment and Embodiment 1 is that the thicknesses of the first and second elastic layers are different, while the amount of liquid metal per unit area is the same. Specifically, in the package 200 of Embodiment 2, the thickness of the first elastic layer is 0.3 mm, and the thickness of the second elastic layer is 1 mm.

[0077] Example 3

[0078] The main difference between this embodiment and embodiment 2 lies in the amount of liquid metal used per unit area in the package 200, resulting in a greater average thickness of the liquid metal layer in embodiment 3 compared to embodiment 2. Specifically, in the packaging method of embodiment 3, step three involves injecting liquid metal into the cavity between the inner and outer packaging structures through a pre-reserved liquid metal inlet on the first elastic layer. The liquid metal is a eutectic gallium indium alloy (EGaIn) (Shenyang Jiabei Trading Co., Ltd.), forming an intermediate liquid metal layer. The amount of liquid metal used per unit area is 0.2 g / cm³. 2 The liquid metal inlet is sealed to obtain the encapsulated body.

[0079] Example 4

[0080] The main difference between the package 200′ in this embodiment and the package 200 in embodiment 3 is that the surface of the first elastic layer facing the second elastic layer has a protrusion integrally formed with the first elastic layer. The height of the protrusion is 0.2±0.01mm, the distance between the protrusions is 0.2±0.01mm, the protrusion is frustum-shaped, the bottom diameter is 0.2mm, and the top diameter is 0.1mm. The protrusion and the first elastic layer are formed by mold casting, and plasma surface treatment is used to improve the bonding force between the protrusion and the gas barrier layer. A copper foil with a thickness of 0.05mm is formed on the top of the protrusion by vapor deposition.

[0081] Example 5

[0082] The main difference between this embodiment and Embodiment 1 is that the dimensions of each layer of the package 200 are different. Specifically, the package of Embodiment 5 includes the following structural components:

[0083] Inner packaging structure: formed by a second elastic layer surrounding and sealing the object to be packaged; wherein, the second elastic layer is a PDMS inner layer with a thickness of 2mm;

[0084] Outer packaging structure: formed by a first elastic layer surrounding and sealing the inner packaging structure; wherein the first elastic layer is a PDMS outer layer with a thickness of 1 mm;

[0085] Intermediate liquid metal layer: Formed by filling the remaining space between the inner and outer packaging structures with a liquid metal layer; the liquid metal is a eutectic gallium indium alloy (EGaIn), with a content of 0.60 g / cm².2 .

[0086] Comparative Example 1

[0087] The main difference between this comparative example and Examples 2-4 is that it does not use a liquid metal layer, that is, it only has two elastic layers, and its package specifically includes the following structure:

[0088] Inner packaging structure: formed by a second elastic layer surrounding and sealing the object to be packaged; wherein, the second elastic layer is a PDMS inner layer with a thickness of 1mm;

[0089] Outer packaging structure: formed by a first elastic layer surrounding and sealing the inner packaging structure; wherein the first elastic layer is a PDMS outer layer with a thickness of 0.3 mm.

[0090] The package in this comparative example can be prepared either by first forming an inner package structure and then forming an outer package structure around the inner package structure, or by first joining the first elastic layer and the second elastic layer to obtain two elastic composite layers, and then surrounding and sealing the object to be packaged.

[0091] Comparative Example 2

[0092] The main difference between this comparative example and Examples 2-4 is that a liquid metal layer is not used, but a 0.05 mm thick aluminum foil is deposited between two elastic layers by vapor deposition. The package specifically includes the following structure:

[0093] Inner packaging structure: formed by a second elastic layer surrounding and sealing the object to be packaged; wherein, the second elastic layer is a PDMS inner layer with a thickness of 1mm;

[0094] Outer packaging structure: formed by a first elastic layer surrounding and sealing the inner packaging structure; wherein the first elastic layer is a PDMS outer layer with a thickness of 0.3 mm.

[0095] The package in this comparative example is prepared by first depositing aluminum foil onto a second elastic layer to form a metal composite layer, then bonding a first elastic layer to the aluminum foil side of the metal composite layer, and finally surrounding and sealing the object to be packaged to obtain the package.

[0096] Performance Tests and Results

[0097] Water vapor and oxygen permeability tests were conducted on the composite layered structures of the encapsulations in Examples 1-5 and Comparative Examples 1-2 to compare the barrier performance of each encapsulation under unstretched and 20% stretching conditions. The stretching was performed simultaneously on the first and second elastic layers in the same plane.

[0098] A water vapor transmission rate (WVTR) permeation analyzer (AQUATRAN 3, AMETEK MOCON) was used to measure the water transmission rate. The measurement temperature was set to 25°C. Samples from Examples 1-4 and Comparative Examples 1-2 were placed between two chambers with different water vapor partial pressures; the relative humidity of one chamber was set to 90%, and the relative humidity of the other chamber was set to 0%. The measurement was performed at a depth of 2.3 cm⁻¹. 2 The water vapor permeability through the sample over its area was measured.

[0099] An oxygen permeability (OTR) permeation analyzer (OX-TRAN 2 / 22H, AMETEK MOCON) was used to measure oxygen permeability. The test temperature was set to 25°C. One side of the sample contained oxygen, and the other side contained nitrogen at the same pressure; the partial pressure difference of oxygen on both sides of the sample was set to one standard atmosphere. The sample test surface area was 28.3 cm². 2 .

[0100] Breathability T (cc / day / cm) 2 ), defined by the following equation:

[0101] T = J / s

[0102] In the formula, J is the gas flux through the sample per unit time, in cc / day; s is the sample surface area, in cm². 2 .

[0103] The material composition and test results of Examples 1-5 and Comparative Examples 1-2 are shown in Table 1.

[0104] Table 1. Material composition and test results of Examples 1-5 and Comparative Examples 1-2

[0105]

[0106] According to the test results in Table 1, the oxygen permeability of samples from Examples 1-5 under 20% tensile condition was 8.5 × 10⁻⁶. -7 cc / day / cm 2 Below that, and with a water vapor transmission rate of 8×10 -7 cc / day / cm 2 As can be seen below, the composite structure and its encapsulation of the present invention not only have excellent gas and water barrier performance in a static environment, but also maintain their gas and water barrier performance well under 20% stretching conditions. It can provide flexible, stretchable and excellent sealing performance encapsulation protection for devices, making it an ideal multifunctional encapsulation material.

[0107] Specifically, in Examples 1 and 2, the amount of liquid metal layer per unit area is the same, but the thickness of the elastic layer is different, and the overall barrier properties are similar. In Example 2, which has a larger elastic layer thickness, it can better resist the contact pressure caused by stretching and longitudinal thinning, and therefore the water vapor permeability is slightly lower.

[0108] Examples 2 and 3 have the same elastic layer, but differ in the amount of liquid metal per unit area. Example 3, with a larger amount of liquid metal, exhibits a liquid metal layer with a greater average thickness, and its oxygen permeability and water vapor permeability under static and 20% tensile conditions are better than those of Example 2. The comparison of Examples 1-3 shows that the barrier performance of the samples is mainly reflected by the liquid metal layer, while the influence of the elastic layer is relatively small.

[0109] The elastic layer and liquid metal usage in Examples 3 and 4 are basically the same, and the oxygen permeability and water vapor permeability in static conditions are also basically the same; however, the protrusion in Example 4 demonstrates a better ability to maintain barrier performance.

[0110] Compared with Examples 1-4, Example 5 has the largest amount of liquid metal per unit area, which can better meet the extrusion deformation caused by 20% stretching. Therefore, its oxygen permeability and water vapor permeability are better under both static and 20% stretching conditions.

[0111] Compared to soft PDMS and flowable LM, the protrusions extend in a direction perpendicular to the elastic layer, which can resist deformation and the resulting contact pressure between two PDMS layers. Moreover, the design of its air barrier layer ensures that the barrier performance between the two layers is not destructively reduced even if the layer comes into contact with the opposite elastic layer.

[0112] In contrast, neither Comparative Examples 1 nor 2 used liquid metal. Comparative Example 1, which used only an elastic layer without a liquid metal layer, relied primarily on the elastic layer for its barrier performance, thus its barrier performance was insufficient for practical needs under both static and tensile conditions. Comparative Example 2, which used aluminum foil instead of liquid metal for barrier properties, exhibited excellent oxygen and water vapor permeability at 0% tension. However, its barrier performance decreased significantly under 20% tensile conditions. This was mainly because its solid-state barrier method struggled to maintain the integrity and density of the solid structure under external forces. Once defects appeared in the foil layer, the overall barrier performance of the package faced destructive and irreversible damage.

[0113] The preferred embodiments of the present invention have been described above to make the spirit of the present invention clearer and easier to understand, and are not intended to limit the present invention. All modifications, substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope summarized by the appended claims.

Claims

1. A packaging structure based on liquid metal, characterized in that: It includes a first elastic layer and a second elastic layer; a cavity is formed between the first elastic layer and the second elastic layer, and liquid metal fills the cavity to form an intermediate liquid metal layer; The amount of liquid metal Q is satisfied by: Q = N × S, where Q is the amount of liquid metal filled in g; and S is the encapsulation area in cm². 2 The value of N is 5 × 10. -6 -2g / cm 2 ; On the surface of the first elastic layer facing the second elastic layer, and / or on the surface of the second elastic layer facing the first elastic layer, there are a plurality of protrusions integrally formed with the elastic layer, and the surface of the protrusions has an air barrier layer.

2. The packaging structure according to claim 1, characterized in that: The first elastic layer and / or the second elastic layer are selected from at least one of natural rubber layer, synthetic rubber layer, ionogel layer, and hydrogel layer.

3. The packaging structure according to claim 1, characterized in that: The liquid metal is selected from at least one of gallium-based liquid metals, indium-based liquid metals, and bismuth-based liquid metals.

4. The packaging structure according to any one of claims 1-3, characterized in that: The value of N ranges from 0.05 to 0.8 g / cm³. 2 .

5. The packaging structure according to any one of claims 1-3, characterized in that, The height of the protrusion is 0.05-1mm, and the distance between adjacent protrusions is 0.01-5mm.

6. A packaging method based on the packaging structure according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Surround and seal the object to be packaged with a second elastic layer to form an inner packaging structure; Step 2: Surround and seal the second elastic layer with the first elastic layer to form an outer encapsulation structure; a receiving cavity is formed between the first elastic layer and the second elastic layer; Step 3: Fill the cavity with liquid metal through the liquid metal inlet reserved on the first elastic layer to form an intermediate liquid metal layer; Prior to step one, several protrusions are integrally formed on the surface of the first elastic layer facing the second elastic layer, and / or on the surface of the second elastic layer facing the first elastic layer. The protrusions are then surface-treated, and the gas barrier layer is then bonded to the surface-treated protrusions.

7. The packaging method according to claim 6, characterized in that, The process of filling the cavity with liquid metal includes the following steps: S1: Cover the liquid metal inlet on the first elastic layer with liquid metal, and then place the outer packaging structure into a sealed container; S2: Evacuate the sealed container to remove air from the sealed container and the cavity. S3: Break the vacuum in the sealed container; liquid metal fills the cavity using the internal and external pressure difference; S4: Remove the sealed container and seal the liquid metal inlet.

8. The packaging method according to claim 7, characterized in that, In step S1, the liquid metal is placed in an open container with a through hole at the bottom, and the through hole is aligned with the liquid metal inlet to form a liquid metal flow channel; then the outer packaging structure and the open container are placed into a sealed container.

9. The packaging method according to any one of claims 6-8, characterized in that, The inner packaging structure can be formed by winding and bonding a single piece of the second elastic layer, or by butt-bonding and bonding multiple pieces of the second elastic layer. and The outer packaging structure is formed by winding and bonding a single first elastic layer, or by bonding multiple first elastic layers together.

10. A package prepared by the packaging method according to any one of claims 6-9, characterized in that, Under a tensile condition of 5-20%, the oxygen permeability of the encapsulation is 2.5 × 10⁻⁶. -6 cc / day / cm 2 Below, the water vapor transmission rate is 8.0 × 10⁻⁶. -7 cc / day / cm 2 the following.

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