Conductive adhesive, terminal device, and method for manufacturing conductive adhesive

Abstract

The application provides a conductive adhesive, a manufacturing method thereof, and a terminal device using the conductive adhesive. The conductive adhesive is used to connect a first component and a second component. The conductive adhesive comprises an adhesive body and a conductive body. The adhesive body comprises a first through hole penetrating through opposite surfaces of the adhesive body, and the conductive body is located in the first through hole. The adhesive body has adhesion. The conductive adhesive has the advantages of reducing activation pressure, reducing working height, reducing RSE, etc.

Description

Technical Field

[0001] This application relates to the field of conductive technology, and in particular to a conductive adhesive, a terminal device, and a method for manufacturing the conductive adhesive. Background Technology

[0002] With the continuous development of mobile communication technology, terminal devices are becoming increasingly functional and complex in their internal structure. The application scenarios requiring conductive structures for communication are also expanding, leading to interference issues between some internal components. For example, high activation pressure on the conductive structure can damage other components (e.g., causing film marks on the screen); a large operating height of the conductive structure contradicts the slim and lightweight design of terminal devices; and poor conductivity can generate nonlinear products such as third harmonic distortion and passive intermodulation (PIM), thereby increasing radiated spurious emissions (RSE) in the terminal device. Therefore, a new solution is urgently needed to address these problems. Summary of the Invention

[0003] In view of this, it is necessary to provide a conductive adhesive that can simultaneously reduce activation pressure, reduce working height, and reduce RSE in order to solve the above problems.

[0004] In a first aspect, embodiments of this application provide a conductive adhesive for conducting a first element and a second element. The conductive adhesive includes an adhesive body and a conductor. The adhesive body includes a first surface, a second surface, and a first through-hole, the first through-hole penetrating the first surface and the second surface; the conductor is located in the first through-hole, and the adhesive body has adhesive properties; wherein, before the conductive adhesive is compressed, the conductor includes at least one conductive channel to conduct the first surface and the second surface.

[0005] The adhesive itself possesses adhesive properties, enabling the bonding of the first and second components without the need for additional adhesive, thus eliminating the need for adhesives in related technologies and reducing the working height. During assembly, it can bond the first and second components for pre-fixation, facilitating the assembly of the first component, conductive adhesive, and second component. The conductive adhesive possesses conductive channels before compression, requiring no significant pressure for activation. Applying pressure increases the density of these conductive channels, which, when the conductors connect the first and second components, helps reduce impedance and improves the conductivity of the conductive adhesive. This allows the conductive adhesive to be used in applications requiring weak force connections. The high compressibility of the conductive adhesive further reduces the working height. Furthermore, the conductive adhesive can reduce the generation of nonlinear products, thereby reducing RSE (Resistant Surface Emissions).

[0006] In conjunction with the first aspect, in one possible implementation, the conductive adhesive further includes a dispersion medium located in the first through-hole; the conductor includes a plurality of conductive particles located in the dispersion medium; before the conductive adhesive is compressed, at least a portion of the plurality of conductive particles forms a conductive channel.

[0007] When the conductive adhesive is compressed, the adhesive deforms, and multiple conductive particles are displaced until at least some of the conductive particles are further interconnected to form more conductive channels, that is, to increase the density of conductive channels. This helps to reduce impedance and thus improve the conductivity of the conductive adhesive.

[0008] In conjunction with the first aspect, in one possible implementation, the conductive adhesive is used to conduct the first element and the second element along a first direction, and the adhesive further includes a side surface that connects the first surface and the second surface; the area ratio of conductive particles on the first surface is greater than the area ratio of conductive particles on the side surface, and / or the area ratio of conductive particles on the second surface is greater than the area ratio of conductive particles on the side surface.

[0009] Since the conductive adhesive is used to achieve conductivity along the first direction, increasing the area ratio of conductive particles on the first surface is beneficial to increasing the contact probability between the conductive particles and the first element on the first surface, increasing the density of conductive channels, reducing impedance, and improving the conductivity of the conductive adhesive. Increasing the area ratio of conductive particles on the second surface is beneficial to increasing the contact probability between the conductive particles and the second element on the second surface, increasing the density of conductive channels, reducing impedance, and improving the conductivity of the conductive adhesive. At the same time, during the compression process, the adhesive body preferentially deforms along the first direction. As the compression amount increases, the adhesive body overflows and expands along the plane perpendicular to the first direction. Under the premise of achieving conductivity, the conductive particles are displaced synchronously with the adhesive body, which helps to prevent the formation of hard spots on the first and second surfaces used for bonding.

[0010] In conjunction with the first aspect, in one possible implementation, the conductor includes a second through-hole, in which conductive adhesive is located.

[0011] Both the adhesive and the conductor are three-dimensional interconnected porous network structures, interwoven with each other. The conductor's three-dimensional interconnected porous network structure allows for linear contact between the first and second elements, which helps reduce the generation of nonlinear products and thus reduces RSE. Furthermore, the interconnected structure of the conductor itself reduces or even eliminates the content of isolated particles, further reducing nonlinear products and thus reducing RSE. The interweaving of the conductor and adhesive allows the adhesive to absorb stress during conductor compression, preventing cracks and reducing nonlinear products, thus further reducing RSE.

[0012] In conjunction with the first aspect, in one possible implementation, the adhesive includes a first through-hole extending through the first surface and the second surface in a first direction, and the conductive adhesive is used to conduct the first element and the second element after being compressed in the first direction and to bond the first element and / or the second element.

[0013] The first via extends through the first surface and the second surface along a first direction, and the conductor extends generally along the first direction and is located in the first via. The linear conductor has a relatively unidirectional extension direction and can preferentially extend generally along the first direction, which is beneficial for forming a conductive channel that is linearly conductive along the first direction, reducing the generation of nonlinear products, and thus reducing RSE.

[0014] In conjunction with the first aspect, in one possible implementation, the conductive adhesive further includes a conductive layer; the conductive layer is located on a first surface and is used to connect and conduct a first element; and / or the conductive layer is located on a second surface and is used to connect and conduct a second element.

[0015] The conductive layer is used to increase the planar contact of the conductive adhesive. When the conductive adhesive is used to conduct the first component and the second component, the conductive layer and the first component or the second component are in surface contact, which can increase the contact area between the conductive adhesive and the first component or the second component, reduce the contact resistance between the conductive adhesive and the first component or the second component, and improve the conductivity between the conductive adhesive and the first component or the second component.

[0016] In conjunction with the first aspect, in one possible implementation, the conductor and the conductive layer are connected before the conductive adhesive is compressed.

[0017] Before the conductive adhesive is compressed, the conductor and the conductive layer are in contact with each other, which helps to improve the connection reliability between the conductive layer and the conductor.

[0018] Secondly, embodiments of this application also provide a terminal device, including a first element, a second element, and a conductive adhesive as described in the first aspect and any one of the embodiments of the first aspect; the conductive adhesive conducts the first element and the second element; wherein, after the conductive adhesive is compressed, the density of the conductive channel increases.

[0019] The conductive adhesive provided in this embodiment is used to conduct the first and second components. The conductive adhesive has good compressibility and adhesion properties, and can be applied to both weak force connection applications and applications with small working heights. The conductive adhesive can reduce the generation of nonlinear products, thereby helping to reduce RSE.

[0020] In conjunction with the second aspect, in one possible implementation, the working height of the conductive adhesive is less than or equal to 0.2 mm.

[0021] The adhesive has adhesive properties and can bond the first component and the second component without the need for additional adhesive, thus eliminating the need for adhesive in related technologies and reducing the working height. The conductive adhesive has a large compressibility, which is beneficial for further reducing the working height, thereby enabling its application in applications with small working heights. In a third aspect, embodiments of this application also provide a method for manufacturing a conductive adhesive, comprising: providing a first slurry and forming the first slurry into an adhesive having a first through-hole; providing a second slurry, the second slurry comprising a dispersion medium and conductive particles; placing the adhesive in the second slurry; and curing the second slurry after the second slurry fills the first through-hole to obtain a conductive adhesive; wherein the adhesive comprises a first surface, a second surface, and a first through-hole, the first through-hole penetrating the first surface and the second surface, the dispersion medium and conductive particles being located in the first through-hole, and the conductive particles forming a conductive channel to conduct the first surface and the second surface.

[0022] In conjunction with the third aspect, in one possible implementation, after the step of curing the second slurry, the manufacturing method further includes: removing the adhesive and dispersion medium, and melting the conductive particles to form a conductive body with a second through hole; placing the conductive body in a third slurry, and curing the third slurry after the third slurry fills the second through hole to obtain a conductive adhesive, wherein the cured third slurry has good adhesion. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the terminal device provided in the embodiments of this application.

[0024] Figure 2 This is a schematic diagram of a structure in a related technology that uses a metal spring for conduction.

[0025] Figure 3 This is a schematic diagram of a structure that uses FOF foam for conduction in some other related technologies.

[0026] Figure 4 for Figure 3 The stress-strain curve of the insulating adhesive is shown.

[0027] Figure 5 This is a schematic diagram illustrating the activation process of conductive adhesives for some related technologies.

[0028] Figure 6 for Figure 5 The stress-strain curve of the conductive adhesive is shown.

[0029] Figure 7 This is a schematic diagram of the structure of the conductive adhesive provided in an embodiment of this application.

[0030] Figure 8 This is a schematic diagram of the conductive adhesive compression process provided in an embodiment of this application.

[0031] Figure 9 This is a schematic diagram of the conductive process of the conductive adhesive provided in the embodiments of this application.

[0032] Figure 10 This is a flowchart illustrating the fabrication process of the conductive adhesive provided in an embodiment of this application.

[0033] Figure 11 This is a schematic diagram of the structure of the conductive adhesive provided in some other embodiments of this application.

[0034] Figure 12 This is a schematic diagram illustrating the manufacturing process of the conductive adhesive provided in some embodiments of this application.

[0035] Figure 13 This is a flowchart illustrating the fabrication process of the conductive adhesive provided in some embodiments of this application.

[0036] Figures 14 to 16 These are schematic diagrams of the conductive adhesive provided in some embodiments of this application.

[0037] Figure 17 This is a schematic diagram illustrating the manufacturing process of the conductive adhesive provided in some embodiments of this application.

[0038] Explanation of main component symbols

[0039]

[0040]

[0041] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0042] To better understand the above-mentioned objectives, features, and advantages of this application, the application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. Many specific details are set forth in the following description to provide a thorough understanding of this application; the described embodiments are merely some, not all, of the embodiments described in this application.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The term "and / or" as used herein includes all and any combination of one or more of the associated listed items.

[0044] In the various embodiments of this application, for ease of description and not limitation, the term "connection" used in the patent application specification and claims is not limited to physical or mechanical connections, whether direct or indirect. Terms such as "upper," "lower," "above," "below," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship also changes accordingly.

[0045] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of the terminal device 100 provided in an embodiment of this application. In this embodiment, the terminal device 100 is a mobile phone. In other embodiments, it includes at least one of the following: mobile phone, foldable electronic device, tablet computer, desktop computer, laptop computer, handheld computer, laptop, ultra-mobile personal computer (UMPC), netbook, cellular phone, personal digital assistant (PDA), augmented reality (AR) device, virtual reality (VR) device, artificial intelligence (AI) device, wearable device, in-vehicle device, smart home device, or smart city device. This application does not limit the specific type of the terminal device 100.

[0046] The terminal device 100 includes components that need to be conductive. For ease of explanation, these components are defined as a first component 21 and a second component 22, which are conductively connected through a conductive structure. The first component 21 can be any one of a screen, lens module, antenna, mid-frame, circuit board, spring, shielding cover, back cover, or decorative component; the second component 22 can also be any one of the following: screen, lens module, antenna, mid-frame, circuit board, spring, shielding cover, back cover, or decorative component. The first component 21 and the second component 22 can be the same or different. It is understood that the specific names of the first component 21 and the second component 22 are specific to the terminal device 100, and the names are merely illustrative. In other embodiments, the names of the first component 21 and / or the second component 22 are not limited to these. In different application scenarios, the conditions required for the first component 21 and the second component 22 to achieve conductivity may differ.

[0047] Taking mobile phones as an example, as mobile phones develop towards multi-functionality, thinness, and foldability, the requirements that mobile phones need to meet are also getting higher and higher. Figure 1The phone shown is a foldable phone. It can include components such as a back cover 11, a mid-frame 12, a motherboard 13, a battery 14, and a screen (not shown). The mid-frame 12 is located between the screen and the back cover 11. The mid-frame 12, screen, and back cover 11 together form a receiving space, within which components such as the battery 14 and motherboard 13 are located. This is understandable. Figure 1 Only some of the phone's components are shown, not all of them.

[0048] To reduce the weight of the phone, structural support components 151 can be made of lighter materials, such as using carbon fiber instead of titanium alloy in the support frame of the screen 15 or the battery compartment housing the battery 14. To achieve a thinner and lighter design, functional components in the phone can be made ultra-thin, for example, the thickness of the back cover 11 can be less than or equal to 0.3mm. These technological advancements pose a dual challenge to the conduction scheme in the terminal device 100: stable conduction must be achieved in a highly compressed physical space (e.g., in applications where the working height of the conductive structure is less than 0.2mm), while simultaneously meeting the sensitivity requirements of the radio frequency structure to weak force connections.

[0049] For example, carbon fiber has lower strength than titanium alloy. During assembly, the pressure acting on the weaker structural support 151 needs to be appropriately reduced; however, this reduction in pressure decreases the stability of the electrical connection of the conductive structure. Furthermore, the layout of radio frequency structures in mobile phones (such as antennas on decorative parts, antennas on the back cover 11, and antennas on the mid-frame 12) generally exhibits weak mechanical pressure resistance. Using metal springs 23 or FOF foam 24 (also known as conductive fabric pads) as conductive structures for electrical connections is insufficient to meet the requirements for weak-force connections. Specifically, weak-force connections (i.e., lower pressure applied to the conductive structure) affect conductivity and easily lead to the generation of nonlinear products such as third harmonics and passive intermodulation (PIM) at the contact interface. The radiated spurious emissions (RSE) generated by these nonlinear products are difficult to meet the terminal device 100 acceptance criteria.

[0050] Please see Figure 2 , Figure 2This is a schematic diagram of a structure using a metal spring 23 for conduction in related technologies. Specifically, the metal spring 23 is used to achieve conduction between the first element 21 and the second element 22. The support member 151 is made of carbon fiber and supports the screen 15. A plating layer 152 is provided on the surface of the support member 151 facing away from the screen 15. Part of the surface of the plating layer 152 is connected to the flexible circuit board 16 (i.e., the first element 21). The flexible circuit board 16 is connected and conduction-enabled to the middle frame 12 (i.e., the second element 22) through the metal spring 23. The other part of the surface of the plating layer 152 is connected to the middle frame 12 through foam 153. In this related technology, the pressure required to achieve conduction using the metal spring 23 is relatively large, but the strength of carbon fiber is low. The strength of carbon fiber is insufficient to support the pressure exerted on the metal spring 23, which may lead to damage to the support member 151 or cause film marks to appear on the screen 15.

[0051] Please see Figure 3 , Figure 3 This is a schematic diagram of a structure using FOF foam 24 for conduction in a related technology on the other side. Specifically, FOF foam 24 is used to achieve conduction between the first element 21 and the second element 22. FOF foam 24 includes a foam core 243, thermosetting adhesive 242, conductive cloth 241, and insulating adhesive 244. The thermosetting adhesive 242 bonds the foam core 243 and the conductive cloth 241. The conductive cloth 241 is semi-enclosed to connect and conduct the first element 21 and the second element 22. The insulating adhesive 244 is adjacent to the ends of the thermosetting adhesive 242 and the conductive cloth 241, and bonds the foam core 243 and the second element 22.

[0052] Conductive cloth 241 is woven from warp and weft threads, and its compressibility is relatively low; thermosetting adhesive 242 is also difficult to compress after curing; insulating adhesive 244 also has relatively low compressibility (see [reference]). Figure 4 , Figure 4 The stress-strain curve of the insulating adhesive 244 provided for this related technology is limited by the compressibility of the conductive cloth 241 and the thermosetting adhesive 242. The non-porous area of ​​the foam core 243 includes the skeleton and non-through holes. When compressed, the foam core 243 is limited by the structure and properties of the material itself, and must maintain a certain degree of elasticity and toughness. Therefore, the compressibility of the foam core 243 is limited. Therefore, using FOF foam 24 to achieve conductivity results in a relatively large working height of the conductive structure, which is difficult to meet the requirement of a thinner and lighter terminal device 100.

[0053] Please see Figure 5 , Figure 5 This is a schematic diagram illustrating the activation process of the conductive adhesive 30' provided for some related technologies. In other related technologies, a soft and elastic conductive adhesive 30' is used as a conductive structure to achieve the conduction of the first element 21 and the second element 22, which can reduce the working height. Please refer to [link / reference needed]. Figure 6 , Figure 6The stress-strain curve of the conductive adhesive 30' provided for this related technology. The conductive adhesive 30' includes a matrix 301 and conductive particles 321, wherein the conductive particles 321 are dispersed in the matrix 301 and the matrix 301 coats the conductive particles 321.

[0054] The conductive adhesive 30' needs to be compressed and activated during use. The dispersed conductive particles 321 pierce the substrate 301 and connect to form conductive channels d, thereby enabling the conduction of the first element 21 and the second element 22. Therefore, a relatively large pressure needs to be applied to the conductive adhesive 30' so that the conductive particles 321 can pierce the substrate 301 and achieve conductivity. Alternatively, increasing the particle size of the conductive particles 321 can also facilitate piercing the substrate 301, but increasing the particle size will reduce the density of the conductive particles 321, thus reducing the density of the conductive channels d and increasing the impedance. Conductive particles 321 that do not pierce the substrate 301 become isolated particles 321' (i.e., conductive particles 321 that are not part of the conductive channels d). During the conduction process, the presence of isolated particles 321' reduces the density of the conductive channels d, increases the impedance, and generates nonlinear products, thereby increasing the resistance-resistance ratio (RSE). Furthermore, the adhesiveness and conductivity of the conductive adhesive 30' are related to the volume fraction of the substrate 301 and the volume fraction of the conductive particles 321. A larger volume fraction of the substrate 301 results in better adhesive performance of the conductive adhesive 30'; however, a correspondingly smaller volume fraction of the conductive particles 321 leads to a lower density of conductive channels (d), resulting in poorer conductivity of the conductive adhesive 30' and increased generation of nonlinear products, thus increasing RSE. Conversely, a larger volume fraction of the conductive particles 321 results in a higher density of conductive channels (d), leading to better conductivity of the conductive adhesive 30' and reduced generation of nonlinear products; however, a smaller volume fraction of the substrate 301 results in poorer adhesive performance of the conductive adhesive 30'. Therefore, it is difficult for the conductive adhesive 30' to simultaneously satisfy both mechanical and conductive properties.

[0055] As mobile phone functions become increasingly sophisticated, the frequency bands covered by the antennas on these phones are expanding. To maintain antenna efficiency, it's also necessary to achieve a thinner and lighter terminal device 100. For example, in under-display grounding applications, the area where the antenna is close to the screen 15 needs to be grounded through the screen 15 to compensate for electromagnetic interference. The conductive structure can be placed near the outer side of the phone (near the adhesive backing). However, traditional conductive structures (metal spring 23, FOF foam 24, etc.) require high pressure to activate their conductivity, and increased pressure can easily create film marks on the screen 15, causing deformation. The pressure required to activate the conductive adhesive 30 is less than that required to activate the metal spring 23 and FOF foam 24. However, the conductive adhesive 30 contains isolated particles 321', which can generate nonlinear products, thus increasing RSE (Reactive Electron Sequence).

[0056] Please see Figure 7 , Figure 7 This is a schematic diagram of the conductive adhesive 30 provided in an embodiment of this application. The conductive adhesive 30 is used to conduct the first element 21 and the second element 22, and the conductive adhesive 30 can solve at least one of the above-mentioned problems.

[0057] The conductive adhesive 30 may include an adhesive body 31 and a conductor 32. The adhesive body 31 includes a first surface 312 and a second surface 313. The first surface 312 is used to connect with the first element 21, and the second surface 313 is used to connect with the second element 22. The adhesive body 31 has adhesive properties. The adhesive body 31 also includes a first through-hole 311, in which the conductor 32 is located. Before the conductive adhesive 30 is compressed, the conductor 32 includes at least one conductive channel d to conduct the first surface 312 and the second surface 313.

[0058] The adhesive 31 has adhesive properties, and its peel force can be greater than or equal to 3 N / cm, specifically 6 N / cm, 15 N / cm, 30 N / cm, 42 N / cm, 50 N / cm, or any value within the range of any two of the above values. The adhesive 31 can be used to directly bond the first element 21 and the second element 22 without the need for additional adhesives (such as thermosetting adhesive 242, insulating adhesive 244, etc.), thus eliminating the need for adhesives in related technologies and reducing the working height. Furthermore, during the assembly of the first element 21, conductive adhesive 30, and second element 22, the adhesive 31 can bond the first element 21 and the second element 22 to pre-fix them, facilitating the assembly of the first element 21, conductive adhesive 30, and second element 22, and preventing the first element 21 and / or the second element 22 from reacting with the conductive adhesive 30. Displacement; the conductive adhesive 30 has conductive channels d before compression, which do not require large pressure to activate. When a certain pressure is applied to the conductive adhesive 30, the density of conductive channels d increases. When the conductor 32 conducts the first element 21 and the second element 22, it helps to reduce impedance, thereby improving the conductivity of the conductive adhesive 30. The conductive adhesive 30 can be used in applications requiring weak force connections. The conductive adhesive 30 has a large compressibility, which helps to further reduce the working height (e.g., the working height is less than or equal to 0.2 mm). The conductive adhesive 30 can reduce the generation of nonlinear products, thereby helping to reduce RSE. The conductive adhesive 30 provided in this application embodiment can replace the conductive structure in the related art.

[0059] Please see Figure 8 , Figure 8This is a schematic diagram illustrating the compression process of the conductive adhesive 30 provided in this embodiment. In this embodiment, the conductive adhesive 30 may further include a dispersion medium 33, which is located in the first through-hole 311; the material of the dispersion medium 33 may be the same as or different from the material of the adhesive 31. The conductor 32 includes a plurality of conductive particles 321, which are located in the dispersion medium 33.

[0060] Before the conductive adhesive 30 is compressed, at least a portion of the multiple conductive particles 321 form conductive channels d, which is equivalent to the dispersion medium 33 including through holes for accommodating the conductive channels d. After the conductive adhesive 30 is compressed, the adhesive 31 deforms, and displacement occurs between the multiple conductive particles 321 until at least a portion of the multiple conductive particles 321 are further interconnected to form more conductive channels d, that is, to increase the density of conductive channels d.

[0061] The conductivity mechanism of conductive adhesive 30 can be based on percolation theory, tunneling effect theory, field emission theory, etc. For example, in the application scenario of grounding screen 15, conductive adhesive 30 is used to conduct the grounding between screen 15 and middle frame 12. After activation, conductive particles 321 in conductive adhesive 30 form conductive channels d to conduct the connection between screen 15 and middle frame 12. Among them, the conductive particles 321 forming conductive channels d based on percolation effect and connecting with screen 15 and middle frame 12 is the key to achieving stable conduction and low PIM.

[0062] Based on the Hertz formula for elastic contact (Hertz formula), Holm's electrical contact theory (Holm theory), skin effect, tunneling effect, thermionic emission effect, metal-insulator-metal theory (MIM theory), electrothermal coupling effect, MIM tunneling effect, and MM electrothermal coupling effect, the key parameters of the third harmonic current formula of conductive adhesive 30 can be obtained. Among them, the main factors that can affect the third harmonic current include F, ξ, ρ1, ρ2, η, and kη, where F is the pressure on conductive adhesive 30, ξ is the proportion of MIM contact area, ρ1 and ρ2 are the resistivity between conductive particles 321 and the first element 21 or the second element 22, respectively, η is the areal density of conductive particles 321, and kη is the contact probability between conductive particles 321 and the first element 21 or the second element 22.

[0063] In particular, by adjusting the type of conductive particles 321, the conductivity can be adjusted; by adjusting the volume fraction of conductive particles 321, the contact probability between conductive particles 321 can be adjusted; and by adjusting the morphology of adhesive 31, the density of conductive channels d can be adjusted. This allows the conductive adhesive 30 to simultaneously possess properties such as reducing pressure, reducing working height, reducing the generation of nonlinear products, and preventing film printing. Consequently, the conductive adhesive 30 can be applied to a variety of different application scenarios.

[0064] Please see Figure 9 , Figure 9 This is a schematic diagram of the conductive process of the conductive adhesive 30 provided in this embodiment. The adhesive 31 has multiple openings 3111 inside, forming a three-dimensional interconnected porous network structure. The openings 3111 are spatially distributed anisotropically. The size, shape, and number of openings 3111 are not limited. The same opening 3111 can communicate with one or more adjacent openings 3111. Multiple openings 3111 are interconnected to form a first through-hole 311 with multiple channels. Conductive particles 321 are filled in the first through-hole 311 to form conductive channels d. Because the openings 3111 are spatially distributed anisotropically, the orientation of the first through-hole 311 formed by the interconnection of multiple openings 3111 is also anisotropic.

[0065] The first through-hole 311 formed by multiple openings 3111, in addition to accommodating the conductive particles 321, also facilitates the compressibility of the conductive adhesive 30. The compression amount of the conductive adhesive 30 can be 20%-70%, specifically 25%, 32%, 45%, 55%, 64%, or any value within the range of any two of the above values; at the same time, the conductive adhesive 30 can also withstand greater pressure to ensure that the structure of the conductive adhesive 30 does not collapse after compression, and the pressure range that can be withstood can be 20kPa-70kPa, specifically 25kPa, 36kPa, 45kPa, 55kPa, 66kPa, or any value within the range of any two of the above values.

[0066] The adhesive 31 is in a non-liquid state and may include synthetic resins, plasticizers, fillers, stabilizers, and other components. The components providing adhesion include, but are not limited to, viscoelastic polyurethane, thermoplastic elastomers (TPE / TPV), modified polyurethane-based composites, silicone gel, acrylic acid, and vinyl acid. These components themselves possess viscoelasticity, providing adhesive properties such as initial tack, adhesion, cohesion, and bond strength to the adhesive 31. Viscoelastic polyurethane can be generated by reacting polyols with polyisocyanates, forming a porous network structure after foaming. Its viscoelasticity originates from its glass transition temperature (Tg) being close to room temperature, resulting in a delayed and rate-dependent response to pressure. After curing, it can slowly recover its shape (viscous) while also possessing elastic support. Thermoplastic elastomers can be based on styrene-based elastomers (such as SBS and SEBS), forming a porous structure through physical or chemical foaming. Their viscoelasticity stems from the combination of the processability of thermoplastic plastics and the elasticity of rubber, forming an interpenetrating network structure through physical cross-linking. Modified polyurethane-based composites can have their viscoelasticity and porous structure enhanced by adding functional fillers or coatings. Acrylic acid and vinyl acid, upon contact with object surfaces, generate electrostatic attraction, van der Waals forces, and affinity through intermolecular adsorption, thus producing an adhesive effect. The adhesiveness of solid adhesives can be further enhanced by adding water-soluble polymers with strong adhesion, such as polyvinyl alcohol. Silicone gels, whose main components may include polydimethylsiloxane, crosslinking agents, and other additives, exhibit good elasticity.

[0067] In some embodiments, the elastic modulus of the silicone gel can range from 1 kPa to 70 kPa, specifically 3 kPa, 15 kPa, 36 kPa, 45 kPa, 56 kPa, or any value within the range of any two of the above values. The specific manufacturing process of the adhesive 31 is not limited. In some embodiments, a foaming process can be used to fabricate the adhesive 31, which forms multiple internal openings 3111.

[0068] The first surface 312 and the second surface 313 can be parallel to each other or have other positional relationships. The first through hole 311 penetrates the first surface 312 and the second surface 313, exposing the conductive particles 321 on the first surface 312 and the second surface 313. Before the conductive adhesive 30 is compressed, at least some of the multiple conductive particles 321 are connected to form at least one conductive channel d; after the conductive adhesive 30 is compressed, the multiple conductive particles 321 are further connected, and the density of the conductive channel d increases.

[0069] The material, shape, and particle size of the conductive particles 321 are not specifically limited and can be adjusted according to actual needs. For example, the material of the conductive particles 321 includes, but is not limited to, metals, carbon-based materials, and conductive composite materials. Metal materials can include, but are not limited to, gold, silver, copper, aluminum, and nickel. In some embodiments, the metal material is preferably gold, silver, copper, or aluminum, which have an elastic modulus of less than 140 GPa. The elastic modulus of gold is approximately 78 GPa, that of silver is approximately 83 GPa, that of copper is approximately 110-130 GPa, that of nickel is approximately 200 GPa, and that of aluminum is approximately 70 GPa. The elastic moduli of gold, silver, copper, and aluminum are relatively low. During the compression of the conductive adhesive 30, the adhesive body 31 deforms. Under a certain pressure, the conductive particles 321 can also deform. The deformation of conductive particles 321 increases the contact probability between them, improves the density of conductive channels d, and reduces impedance, thereby enhancing the conductivity of the conductive adhesive 30. Furthermore, it increases the compressibility of the conductive adhesive 30, thus improving its mechanical properties. Carbon-based materials include, but are not limited to, carbon nanotubes and carbon microspheres. Conductive composite materials include, but are not limited to, carbon-coated metals or metal alloys, and carbon-doped inorganic materials.

[0070] The shape of the conductive particles 321 includes, but is not limited to, at least one of spherical, linear, rod-shaped, needle-shaped, or other irregular shapes. The particle size range of the conductive particles 321 can be at least one of micrometer or nanometer scale, that is, the particle size range of the conductive particles 321 can be a single particle size range or a combination of multiple particle size ranges. For example, the particle size range of the conductive particles 321 can be 5μm-30μm, 50nm-200nm, or a combination of 5μm-30μm and 50nm-200nm, etc.

[0071] The conductive adhesive 30 can have a regular shape, such as a cuboid, sphere, or ellipse, or it can have other irregular shapes. To facilitate understanding of the structure of the conductive adhesive 30, a cuboid structure is used as an example. A three-dimensional coordinate system with X, Y, and Z axes is defined, with the X, Y, and Z axes perpendicular to each other. The conductive adhesive 30 adheres to the first element 21 and the second element 22 along the Z-axis direction (i.e., the first direction), and the first surface 312 and the second surface 313 are arranged along the Z-axis direction. It can be understood that in practical applications, the structure of the conductive adhesive 30 is not limited to a cuboid structure. Furthermore, the shape of the conductive adhesive 30 before and after compression can remain roughly the same or change. The specific shape of the conductive adhesive 30 can be modified according to the actual application scenario.

[0072] The adhesive 31 also includes a side surface 314, which connects the first surface 312 and the second surface 313. The area ratio of conductive particles 321 on the first surface 312 is greater than the area ratio of conductive particles 321 on the side surface 314, and / or the area ratio of conductive particles 321 on the second surface 313 is greater than the area ratio of conductive particles 321 on the side surface 314. In this embodiment, the adhesive 31 includes four sides 314: front, back, left, and right. The area ratio of conductive particles 321 on the first surface 312 can be greater than or equal to 70%, specifically 72%, 75%, 77%, 80%, 85%, or any value within the range of any two of the above values. The area ratio of conductive particles 321 on the second surface 313 can be greater than or equal to 70%, specifically 72%, 75%, 77%, 80%, 85%, or any value within the range of any two of the above values. The area ratio of conductive particles 321 on the sides 314 can be 30%-70%, specifically 35%, 40%, 46%, 53%, 65%, or any value within the range of any two of the above values.

[0073] Since the conductive adhesive 30 is used to achieve conductivity along the Z-axis direction, increasing the area ratio of conductive particles 321 on the first surface 312 is beneficial to increasing the contact probability between the conductive particles 321 on the first surface 312 and the first element 21, increasing the density of conductive channels d, reducing impedance, and improving the conductivity of the conductive adhesive 30. Increasing the area ratio of conductive particles 321 on the second surface 313 is beneficial to increasing the contact probability between the conductive particles 321 on the second surface 313 and the second element 22, increasing the density of conductive channels d, reducing impedance, and improving the conductivity of the conductive adhesive 30. At the same time, during the compression process of the conductive adhesive 30, the adhesive body 31 preferentially deforms along the Z-axis direction. As the compression amount increases, the adhesive body 31 overflows and expands along the XY plane (i.e., the plane determined by the X-axis direction and the Y-axis direction). Under the premise of achieving conductivity, the conductive particles 321 are displaced synchronously along the XY plane with the adhesive body 31, which helps to prevent the conductive particles 321 from forming hard spots on the first surface 312 and the second surface 313 used for bonding. When the conductive adhesive 30 is used to bond the screen 15, hard particles can easily cause film marks on the screen 15. Adjusting the area ratio of the conductive particles 321 in different directions can help improve the film mark phenomenon.

[0074] Please see Figure 10 , Figure 10 This is a flowchart illustrating the fabrication process of the conductive adhesive 30 provided in the embodiments of this application. Please refer to it in conjunction with the above. Figure 9 The conductive adhesive 30 can be formed by the following steps:

[0075] Step S11: Provide a first slurry and form the first slurry into an adhesive 31 having a first through hole 311.

[0076] The first slurry can be foamed and cured to obtain an adhesive 31. The first slurry can contain polyester and / or silicone gel, and appropriate raw materials can be selected according to the specific foaming process. The foaming process can include chemical foaming, physical foaming, and mechanical foaming. After the first slurry is foamed and cured, an adhesive 31 with multiple openings 3111 is formed, and the multiple openings 3111 are interconnected to form a first through hole 311.

[0077] Step S12: Provide a second slurry, which includes a dispersion medium 33 and conductive particles 321. Place the adhesive 31 in the second slurry. After the second slurry fills the first through hole 311, cure the second slurry to obtain conductive adhesive 30.

[0078] Conductive particles 321 are dispersed in dispersion medium 33. Since conductive particles 321 have a large specific surface area and tend to agglomerate, dispersing conductive particles 321 in dispersion medium 33 helps to improve the agglomeration of conductive particles 321, so that after the second slurry fills the first through hole 311, conductive particles 321 can be located more uniformly in the adhesive 31.

[0079] The composition of the dispersion medium 33 can be the same as or different from that of the first slurry. The dispersion medium 33 and the conductive particles 321 are filled together in the first through hole 311. When the composition of the dispersion medium 33 is the same as that of the first slurry, it is beneficial for the dispersion medium 33 to grow on the adhesive 31, which in turn is beneficial for bonding the conductive particles 321 to the adhesive 31.

[0080] The content of conductive particles 321 in the final conductive adhesive 30 can be adjusted by changing conditions such as soaking time and curing temperature.

[0081] In some embodiments, when it is necessary to form conductive adhesive 30 with a difference in area ratio, the surface with the smaller area ratio to be formed is pre-masked during the immersion process. For example, in this embodiment, the four sides 314 (front, back, left, and right) are masked so that conductive particles 321 with a larger area ratio can be formed on the first surface 312 and the second surface 313.

[0082] Please see Figure 11 , Figure 11 The diagram below illustrates the structure of the conductive adhesive 30a provided in other embodiments of this application. The conductive adhesive 30a includes an adhesive body 31 and a conductor 32. The conductive adhesive 30a may also include a conductive layer 34, located on a first surface 312 and / or a second surface 313. The conductive layer 34 is used to increase the planar contact of the conductive adhesive 30a. Figure 11 In the embodiment shown, the conductive layer 34 is located on the second surface 313.

[0083] It is understood that when the conductive layer 34 is located on the first surface 312, the conductive layer 34 can be directly connected to the first element 21, and the second surface 313 of the conductive adhesive 30a can bond the second element 22; when the conductive layer 34 is located on the second surface 313, the conductive layer 34 can be directly connected to the second element 22, and the first surface 312 of the conductive adhesive 30a can bond the first element 21.

[0084] When the conductive adhesive 30a is used to conduct the first element 21 and the second element 22, the conductive layer 34 and the first element 21 or the second element 22 are in surface contact. This increases the contact area between the conductive adhesive 30a and the first element 21 or the second element 22, reduces the contact resistance between the conductive adhesive 30a and the first element 21 or the second element 22, and improves the conductivity between the conductive adhesive 30a and the first element 21 and the second element 22. The conductive adhesive 30a with the conductive layer 34 has a lower pressure resistance than the conductive adhesive 30a without the conductive layer 34. Because the conductive layer 34 is thinner, excessive pressure applied to the conductive adhesive 30a may cause cracks or powdering. The conductive adhesive 30a is suitable for applications with lower pressure.

[0085] Before the conductive adhesive 30a is compressed, the conductor 32 and the conductive layer 34 may or may not be in contact. If the conductor 32 and the conductive layer 34 are not in contact before the conductive adhesive 30a is compressed, they will come into contact after the compression, thus enabling the conductive adhesive 30a to conduct electricity. Before the compression, the conductor 32 and the conductive layer 34 are in contact, which helps to improve the connection reliability between the conductive layer 34 and the conductor 32.

[0086] The conductive layer 34 can be made of metal, conductive composite material, etc. In some embodiments, the method for fabricating the conductive adhesive 30a includes steps S21 and S22. Step S21 is largely the same as step S11, and step S22 can refer to step S12. Specifically, the soaking time of the adhesive 31 in the second slurry can be extended to form the conductive layer 34 on the first surface 312 and / or the second surface 313. Specific parameters (including but not limited to composition, time, temperature, etc.) can be adjusted as needed. In other embodiments, the conductive layer 34 can be formed using physical vapor deposition, chemical vapor deposition, magnetron sputtering, etc.

[0087] Please see Figure 12 , Figure 12This is a schematic diagram illustrating the fabrication process of the conductive adhesive 30b provided in some embodiments of this application. The conductive adhesive 30b may include an adhesive body 31b and a conductor 32b. The adhesive body 31b includes a first through-hole 311, and the conductor 32b is located within the first through-hole 311. The conductor 32b includes a second through-hole 322, and the adhesive body 31b is located within the second through-hole 322. Both the adhesive body 31b and the conductor 32b are three-dimensional interconnected porous network structures, interwoven with each other. When the conductive adhesive 30b is used to bond and conduct electricity to the first element 21 and the second element 22, both the adhesive body 31b and the conductor 32b are compressed and deformed along a first direction.

[0088] The conductor 32b is a three-dimensional interconnected porous network structure. When the conductor 32b conducts the first element 21 and the second element 22, the conductor 32b is in linear contact, which helps to reduce the generation of nonlinear products and thus helps to reduce RSE. Since the conductor 32b is a three-dimensional interconnected porous network structure, the conductors 32b are interconnected with each other, reducing or even eliminating the content of isolated particles 321', which helps to further reduce the generation of nonlinear products and thus helps to reduce RSE. The conductor 32b and the adhesive 31b are intertwined. During the compression of the conductor 32b, the adhesive 31b can absorb the stress of the conductor 32b, which helps to prevent the conductor 32b from cracking, thereby reducing the generation of nonlinear products and thus helping to reduce RSE.

[0089] The first surface 312 and / or the second surface 313 of the adhesive 31b may also be provided with a conductive layer 34 for surface contact with the first element 21 or the second element 22.

[0090] Please see Figure 12 and Figure 13 , Figure 13 This is a flowchart illustrating the fabrication process of conductive adhesive 30b according to some embodiments of this application. Conductive adhesive 30b can be formed by the following steps:

[0091] Step S31: Provide a first slurry and form the first slurry into an adhesive 31 having a first through hole 311. For specific steps, please refer to step S11.

[0092] Step S32: Provide a second slurry, which includes a dispersion medium 33 and conductive particles 321. Place the adhesive 31 in the second slurry. After the second slurry fills the first through hole 311, the second slurry is cured.

[0093] Steps S31 and S32 are largely the same as steps S11 and S12. The difference from step S12 is that, in this embodiment, the conductive particles 321 in the second slurry may include metals, conductive composite materials, etc., but not carbon-based materials. The second slurry may also be a liquid metal, which is a metal or alloy that is liquid at a temperature below the melting point of the adhesive 31 and is paste-like or near-solid at room temperature, such as gallium (melting point 29.76°C), Field alloy (melting point approximately 62°C), Wood's alloy (melting point approximately 70°C), gallium indium tin alloy (melting point approximately ≤25°C), etc. In some embodiments, on the one hand, Ag, Cu, Al, and other particles may be added to the liquid metal to form an alloy, reducing fluidity and making the second slurry paste-like or near-solid at room temperature; on the other hand, compounds containing O, N, etc., may be added to the liquid metal to reduce its surface tension, making the second slurry paste-like or near-solid at room temperature.

[0094] Step S33: Remove the adhesive 31 and the dispersion medium 33 to form a conductor 32b with a second through hole 322.

[0095] The adhesive 31 and dispersion medium 33 can be removed by high-temperature sintering (e.g., at a temperature greater than or equal to 500°C), causing the conductive particles 321 to melt and connect. After removing the adhesive 31 and dispersion medium 33, the space occupied by the adhesive 31 and dispersion medium 33 becomes the second through-hole 322 of the conductive body 32b. During the high-temperature sintering process, isolated particles 321' can connect with other conductive particles 321, reducing the proportion of isolated particles 321'.

[0096] Step S34: Place the conductor 32b in the third slurry. After the third slurry fills the second through hole 322 of the conductor 32b, the third slurry is cured to obtain conductive adhesive 30b.

[0097] The composition of the third slurry can be the same as or different from that of the first slurry. After curing, the third slurry forms an adhesive 31b, which has adhesive properties and is interwoven with the conductor 32b. In some embodiments, the adhesive 31b can be made of a more elastic material than the adhesive 31.

[0098] Please see Figure 14 , Figure 15 and Figure 16 , Figure 14 , Figure 15 and Figure 16 The following are schematic diagrams illustrating the structure of the conductive adhesive 30c provided in some embodiments of this application, wherein... Figure 14 and Figure 15 All are cross-sectional schematic diagrams. Figure 16 This is a top-down view.

[0099] The conductive adhesive 30c may include an adhesive body 31 and a conductor 32c. The adhesive body 31 includes a first surface 312, a second surface 313, and a first through-hole 311. The conductor 32c is located in the first through-hole 311. The first through-hole 311 extends through the first surface 312 and the second surface 313 of the adhesive body 31 along a first direction.

[0100] The first through-hole 311 starts from the first surface 312 of the adhesive body 31 and extends in a straight line along the first direction, or in an approximately straight line within the allowable process error range, until it reaches the second surface 313 of the adhesive body 31, thereby forming a continuous channel inside the adhesive body 31, that is, at least one straight line parallel to the first direction can pass through the first through-hole 311. During the entire penetration process, adjacent first through-holes 311 can also be connected through openings 3111, but the penetration along the first direction is the primary direction through the adhesive body 31.

[0101] The shape of the first through hole 311 in the adhesive 31 can be a regular shape such as a cylinder or prism, or it can be other irregular shapes set according to specific design requirements. When the first through hole 311 is irregular in shape, it is beneficial for the adhesive 31 to be compressed along the first direction, which is beneficial for improving the compressibility of the conductive adhesive 30c.

[0102] The conductor 32c is generally linear, such as a metal wire or carbon nanotube, and can also be a mixture of various materials. The first through-hole 311 extends through the first surface 312 and the second surface 313 along a first direction, and the conductor 32c extends generally along the first direction and is located within the first through-hole 311. The linear conductor 32c has a relatively unidirectional extension direction, preferentially extending generally along the first direction, which is beneficial for forming a linearly conductive channel d along the first direction, reducing the generation of nonlinear products, and thus helping to reduce RSE.

[0103] The conductive adhesive 30c may also include a conductive layer 34, which is located on the first surface 312 and / or the second surface 313.

[0104] Please see Figure 17 , Figure 17 The following is a schematic diagram illustrating the manufacturing process of conductive adhesive 30c provided in some embodiments of this application. The manufacturing method of conductive adhesive 30c may include the following steps:

[0105] Step S41: Provide a first slurry and form the first slurry into an adhesive 31 having a first through-hole 311. For specific steps, please refer to step S11, wherein the foaming process can be adjusted to modify the structure of the first through-hole 311.

[0106] Step S42: Provide a second slurry, which includes a dispersion medium 33 and a conductor 32c. Place the adhesive 31 in the second slurry. After the second slurry fills the first through hole 311, cure the second slurry to obtain conductive adhesive 30c.

[0107] Specifically, a hydrothermal reaction can be used to form a linear conductor 32c in the adhesive 31. For example, both the second slurry and the adhesive 31 are placed in a hydrothermal reactor 40 for hydrothermal reaction. The conductor 32c in the second slurry can be a single material or a mixture of multiple materials. By controlling the hydrothermal reaction conditions, including but not limited to pressure and temperature, a conductive adhesive 30c is formed.

[0108] The areal density of the first through-hole 311 on the first surface 312 is greater than or equal to 30%, specifically it can be 32%, 45%, 57%, 60%, 75%, or any value within the range of any two of the above values; the areal density of the first through-hole 311 on the second surface 313 is greater than or equal to 30%, specifically it can be 32%, 45%, 57%, 60%, 75%, or any value within the range of any two of the above values. The increased areal density of the first through-hole 311 facilitates the entry of the conductor 32c into the first through-hole 311, thereby increasing the volume percentage of the conductor 32c in the conductive adhesive 30c, and thus improving the conductivity of the conductive adhesive 30c.

[0109] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application should not depart from the spirit and scope of the technical solutions of this application.

Claims

1. A conductive adhesive for conducting a first element and a second element, characterized in that, The conductive adhesive includes: An adhesive includes a first surface, a second surface, and a first through-hole, the first through-hole penetrating the first surface and the second surface, and the adhesive has adhesive properties; A conductor is located in the first through hole; Before the conductive adhesive is compressed, the conductor includes at least one conductive channel to connect the first surface and the second surface.

2. The conductive adhesive according to claim 1, characterized in that, The conductive adhesive further includes a dispersion medium located in the first through hole; the conductor includes a plurality of conductive particles located in the dispersion medium; before the conductive adhesive is compressed, at least a portion of the plurality of conductive particles forms the conductive channel.

3. The conductive adhesive according to claim 2, characterized in that, The conductive adhesive is used to conduct the first element and the second element along a first direction. The adhesive also includes a side surface that connects the first surface and the second surface. The area ratio of the conductive particles on the first surface is greater than the area ratio of the conductive particles on the side surface, and / or the area ratio of the conductive particles on the second surface is greater than the area ratio of the conductive particles on the side surface.

4. The conductive adhesive according to claim 1, characterized in that, The conductor includes a second through hole, and the conductive adhesive is located in the second through hole.

5. The conductive adhesive according to claim 1, characterized in that, The adhesive includes a first through hole extending through the first surface and the second surface in a first direction. The conductive adhesive is used to conduct the first element and the second element after being compressed in the first direction and to bond the first element and / or the second element.

6. The conductive adhesive according to any one of claims 1-5, characterized in that, The conductive adhesive further includes a conductive layer; the conductive layer is located on the first surface and connects to and conducts the first element; and / or the conductive layer is located on the second surface and is used to connect to and conduct the second element.

7. The conductive adhesive according to claim 6, characterized in that, Before the conductive adhesive is compressed, the conductor and the conductive layer are connected.

8. A terminal device, characterized in that, include: First component; Second element; as well as The conductive adhesive according to any one of claims 1-7, wherein the conductive adhesive conducts the first element and the second element; wherein, after the conductive adhesive is compressed, the density of the conductive channels increases.

9. The terminal device according to claim 8, characterized in that, The working height of the conductive adhesive is less than or equal to 0.2 mm.

10. A method for preparing a conductive adhesive, characterized in that, include: A first slurry is provided, and the first slurry is formed into an adhesive having a first through-hole; A second slurry is provided, the second slurry comprising a dispersion medium and conductive particles; the adhesive is placed in the second slurry; the second slurry fills the first through-hole and is then cured to obtain the conductive adhesive. The adhesive includes a first surface, a second surface, and a first through-hole. The first through-hole penetrates the first surface and the second surface. The dispersion medium and the conductive particles are located in the first through-hole. The conductive particles form a conductive channel to connect the first surface and the second surface.

11. The method for preparing the conductive adhesive according to claim 10, characterized in that, After the step of curing the second slurry, the manufacturing method further includes: Remove the adhesive and the dispersion medium, and melt the conductive particles to form a conductive body with a second through hole; The conductor is placed in a third slurry, which fills the second through hole and then cures to obtain the conductive adhesive. The third slurry has good adhesion after curing.

Images