Insulating adhesive, insulating adhesive tape, and method for producing insulating adhesive

Abstract

The application discloses an insulating adhesive, an insulating adhesive tape and a preparation method of the insulating adhesive. The insulating adhesive comprises an insulating adhesive body and insulating particles doped in the insulating adhesive body. The breakdown field strength of the insulating particles is greater than that of the insulating adhesive body. Because the breakdown field strength of the insulating particles is greater than that of the insulating adhesive body, the insulating adhesive body is more likely to be broken down than the insulating particles. When an electrostatic discharge current acts on the insulating adhesive, the electrostatic discharge current will break down the insulating adhesive body with poor insulation performance and is more likely to be broken down, bypass the insulating particles with good insulation performance and are more difficult to be broken down, so that the breakdown path of the electrostatic discharge current is lengthened, the breakdown voltage required for breaking down the insulating adhesive is increased, and thus the insulation performance of the insulating adhesive is improved.

Description

[0001] This is a divisional application. The original application has the application number 202111310407.0 and the application date is November 4, 2021. The entire contents of the original application are incorporated herein by reference. Technical Field

[0002] This application relates to the field of insulating adhesive technology, and more particularly to an insulating adhesive, an insulating tape, and a method for preparing the insulating adhesive. Background Technology

[0003] Gaps inevitably exist between the casing components of electronic devices such as mobile phones and tablets. For dust and water protection, insulating tape is typically used to seal these gaps. This insulating tape usually consists of an insulating film and an insulating adhesive layer bonded to it. To make the adhesive layer sticky, it needs to be mixed with adhesive substances, thus making its insulation lower than that of the insulating film, creating a weak point in the insulation. When the casing components on both sides of the gap are insulators, the gap becomes vulnerable to electrostatic discharge (ESD). This ESD current can potentially break down the insulating adhesive layer along the bonding surface, thereby damaging internal components of the electronic device.

[0004] It is evident that whether electronic devices possess sufficient electrostatic discharge (ESD) protection capabilities to prevent ESD largely depends on the insulation performance of the insulating adhesive layer. Therefore, improving the insulation performance of the insulating adhesive layer used for ESD protection is crucial for ensuring the reliability of electronic devices. Currently used methods cannot effectively guarantee the insulation performance of the insulating adhesive layer in the direction of the bonding surface. Summary of the Invention

[0005] This application provides an insulating adhesive, an insulating tape, and a method for preparing the insulating adhesive, which solves the problem in the prior art that the insulating adhesive layer cannot effectively guarantee the insulating performance in the direction of the bonding surface.

[0006] To achieve the above objectives, the embodiments of this application adopt the following technical solutions:

[0007] In a first aspect, an insulating adhesive is provided. The insulating adhesive includes an insulating colloid and insulating particles doped within the insulating colloid. The breakdown field strength of the insulating particles is greater than that of the insulating colloid, and the insulating particles are highly electronegative, non-polar insulating microparticles.

[0008] In this insulating adhesive, because the breakdown field strength of the insulating particles is greater than that of the insulating adhesive body, the insulating adhesive body is more easily broken down than the insulating particles. When an ESD current acts on this insulating adhesive, the ESD current will break down the insulating adhesive body, which has poorer insulation performance and is easier to break down, while bypassing the insulating particles, which have better insulation performance and are more difficult to break down. This makes the breakdown path of the ESD current longer, and the breakdown voltage required to break down the insulating adhesive will increase, thereby improving the insulation performance of the insulating adhesive.

[0009] It should be understood that the insulating particles within the insulating adhesive are embedded within the adhesive body through doping, thus distributing at any location within the adhesive. In other words, the insulating properties of the adhesive are macroscopically indistinguishable in any direction. For ESD currents originating from any direction, the insulating adhesive can increase its breakdown voltage by lengthening the breakdown path of the ESD current, thereby improving its insulation performance in all directions. Based on this, when the insulating adhesive exists as an insulating layer, its insulation performance along the direction of the adhesive surface can naturally be improved.

[0010] In addition, the insulating particles are highly electronegative, non-polar insulating microparticles.

[0011] On the one hand, the insulating particles are highly electronegative insulating particles. It should be noted that "highly electronegative" means that the electronegativity of the insulating particles is higher than that of the insulating colloid.

[0012] In this embodiment, the electronegativity of the insulating particles represents their ability to adsorb electrons. When the electronegativity of the insulating particles is higher than that of the insulating colloid, the insulating particles have high electronegativity. Compared to the case of low electronegativity, higher electronegativity results in a stronger ability to adsorb electrons. Based on this, a large number of electrons are adsorbed by the surface of the insulating particles, reducing the number of electrons in the medium surrounding the insulating particles. As the number of electrons in the medium surrounding the insulating particles decreases, the collisional ionization phenomenon in the medium surrounding the insulating particles weakens, thereby drastically reducing the number of ions in the medium surrounding the insulating particles. This makes the medium surrounding the insulating particles difficult to break down, thus improving the dielectric breakdown resistance of the insulating colloid, i.e., its insulating performance.

[0013] On the other hand, the insulating particles are non-polar. Compared to the case where the insulating particles are polar, when the insulating particles are non-polar, no internal electric field is generated between adjacent insulating particles in the same direction as the breakdown field strength. In this case, the total electric field of the insulating adhesive along the breakdown direction will not be the sum of the internal electric field and the breakdown field strength, thus not weakening the insulating performance of the insulating adhesive.

[0014] Optionally, the insulating material may include rubber or other materials.

[0015] Furthermore, the insulating material used for doping to form insulating particles includes tetrafluoroethylene and / or tetrafluoroethylene polymers. The insulating particles of this insulating material simultaneously possess high electronegativity and non-polarity. Therefore, the high electronegativity ensures that doping of the insulating particles can improve the insulating properties of the insulating adhesive, while the non-polarity ensures that doping of the insulating particles will not weaken the insulating properties of the insulating adhesive.

[0016] Furthermore, the tetrafluoroethylene polymer includes one or more of polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, and perfluoropropyl perfluorovinyl ether-polytetrafluoroethylene copolymer.

[0017] Optionally, the mass ratio of insulating particles to insulating colloid is 30% to 60%. The doping ratio of insulating particles should not be too high or too low. Since insulating particles do not possess adhesiveness, a high doping ratio will reduce the adhesiveness and strength of the insulating colloid. A low doping ratio will not significantly improve the insulating performance of the colloid. In this embodiment, controlling the mass ratio of insulating particles to insulating colloid to be 30% to 60% ensures both the adhesiveness and strength of the insulating colloid, as well as its insulating performance.

[0018] In a second aspect, an insulating tape is provided. The insulating tape includes: a first film layer and an adhesive layer, the adhesive layer being laminated on the first film layer. The adhesive layer is made of the insulating adhesive described in any one of the first aspects.

[0019] In some embodiments of this application, the diameter of the insulating particles is less than one-tenth the thickness of the colloid layer. It should be understood that the diameter of the insulating particles should not be too large or too small. If the diameter of the insulating particles is too large, the non-adhesive insulating particles distributed on the surface of the colloid layer will result in excessively low surface adhesion; the non-adhesive insulating particles distributed within the colloid layer will not easily adhere to the insulating colloid, leading to lower overall strength of the colloid layer. Furthermore, the insulating colloid between pairs of insulating particles will be relatively thin, making the colloid layer prone to cracking.

[0020] In some embodiments of this application, the insulating tape further includes a second film layer. The second film layer is laminated on the surface of the adhesive layer away from the first film layer. The presence of the second film layer protects the adhesive layer before use.

[0021] Thirdly, a method for preparing an insulating adhesive is provided. This method includes: processing an insulating colloid into a molten state; incorporating insulating particles into the molten insulating colloid and mixing them to obtain an insulating adhesive to be treated. The insulating particles have a breakdown field strength greater than that of the insulating colloid, and the insulating particles are highly electronegative, non-polar insulating microparticles. The insulating adhesive to be treated is then cooled to obtain the insulating adhesive.

[0022] Optionally, the insulating material may include rubber or other materials.

[0023] Furthermore, the insulating materials used for doping to form insulating particles include tetrafluoroethylene and / or tetrafluoroethylene polymers.

[0024] Furthermore, the tetrafluoroethylene polymer includes one or more of polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, and perfluoropropyl perfluorovinyl ether-polytetrafluoroethylene copolymer.

[0025] Optionally, the mass ratio of insulating particles to insulating colloid is 30% to 60%.

[0026] It should be noted that the technical effects brought about by any of the embodiments in the second to third aspects can be referred to the technical effects brought about by the corresponding embodiments in the first aspect, and will not be repeated here. Attached Figure Description

[0027] Figure 1a Schematic diagrams of the structure of electronic devices provided in some embodiments of this application;

[0028] Figure 1b for Figure 1a A cross-sectional view obtained by cutting along line A1-A1;

[0029] Figure 1c for Figure 1b A magnified view of a portion of region X in the middle;

[0030] Figure 2 This is a schematic diagram of the insulating adhesive layer in a possible design scheme;

[0031] Figure 3 A cross-sectional structural schematic diagram of the insulating tape provided in some embodiments of this application;

[0032] Figure 4 A comparison diagram showing the influence of insulating particles on the ESD current breakdown path provided in some embodiments of this application;

[0033] Figure 5 A schematic diagram of the breakdown path of ESD current in the medium surrounding insulating particles provided for some embodiments of this application;

[0034] Figure 6 Schematic diagrams illustrating the changes in the number of electrons during an electron avalanche, provided for some embodiments of this application;

[0035] Figure 7 A schematic diagram of polarization of polar molecules under the action of an electric field, provided for some embodiments of the application;

[0036] Figure 8 A cross-sectional structural schematic diagram of the insulating tape provided in other embodiments of this application;

[0037] Figure 9 This is a flowchart illustrating a method for preparing an insulating adhesive, as provided in an embodiment of this application. Detailed Implementation

[0038] In the embodiments of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0039] In the embodiments of this application, "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0040] In this application embodiment, "multiple" refers to two or more (including two).

[0041] In the embodiments of this application, directional terms such as "upper" are defined relative to the orientation in which the components are schematically placed in the accompanying drawings. It should be understood that these directional terms are relative concepts, used for relative description and clarification, and can change accordingly depending on the orientation in which the components are placed in the accompanying drawings.

[0042] Gaps inevitably exist between the casing components of electronic devices such as mobile phones and tablets. For dust and water protection, insulating tape is typically used to seal these gaps. This insulating tape usually consists of an insulating film and an insulating adhesive layer bonded to it. To make the adhesive sticky, the adhesive layer needs to be mixed with adhesive substances, making its insulation lower than that of the insulating film, thus creating a weak point in the insulation. When the casing components on both sides of the gap are insulators, the gap poses a risk of electrostatic discharge. The electrostatic current may break down the insulating adhesive layer, potentially damaging internal components of the electronic device. For easier understanding, the following will combine... Figures 1a to 1c Examples of scenarios where static electricity occurs are provided above.

[0043] For example, Figure 1a This is a schematic diagram of the structure of an electronic device provided in some embodiments of this application. The electronic device 100 is a mobile phone, including a back cover 103, a camera bracket 104 mounted on the back cover 103, and a camera module 106 disposed within the camera bracket 104. Please refer to... Figure 1b , Figure 1b for Figure 1aThe diagram shows a cross-sectional view of the electronic device taken along line A1-A1. As can be seen, the electronic device 100 includes, from bottom to top, a display screen 101, a mid-frame 102, a rear shell 103, a camera bracket 104 mounted on the rear shell 103, and a camera module 106 disposed below the camera bracket 104. Because a gap typically exists between the camera bracket 104 and the rear shell 103, external substances such as liquids and dust may enter the interior of the electronic device 100 through this gap, affecting the reliability of internal components such as the camera module 106. Therefore, the gap 107 is typically sealed below the gap with insulating tape 105.

[0044] Specifically, please refer to Figure 1c , Figure 1c for Figure 1b A magnified view of region X in the middle. This figure illustrates the gap 107 between the camera bracket 104 and the rear shell 103. To block this gap 107, the insulating tape 105 typically consists of an insulating film 1051 and an insulating adhesive layer 1052 attached to the insulating film 1051. The insulating film 1051 is adhered to the rear shell 103 areas on both sides of the camera bracket 104 and is bonded by the insulating adhesive layer 1052. It should be noted that since the camera bracket 104 and the rear shell 103 are typically made of non-metallic insulating materials, when static charge accumulates to a certain level, an ESD phenomenon will occur through the gap 107, thereby generating an ESD current. Although the aforementioned insulating adhesive layer 1052 can prevent substances from entering the interior of the electronic device 100, it cannot prevent ESD currents exceeding its insulation capacity. The ESD current may break through the insulating adhesive layer 1052 in the direction indicated by the dashed arrow in the figure, thereby damaging internal components such as the camera module 106.

[0045] Depend on Figure 1c It is evident that whether electronic device 100 possesses sufficient electrostatic discharge (ESD) protection capability to prevent ESD largely depends on the insulation performance of the insulating adhesive layer 1052. Therefore, improving the insulation performance of the insulating adhesive layer 1052 used for ESD protection is crucial for ensuring the reliability of electronic device 100. Currently, a commonly used approach is to improve the insulation performance by designing the insulating adhesive layer 1052 as an anisotropic insulating adhesive structure.

[0046] For example, please refer to Figure 2 , Figure 2 This is a schematic diagram of the insulating adhesive layer in a possible design. The insulating adhesive layer 1052 is a composite layer structure, comprising a first insulating adhesive layer M1, a PET film layer M2, and a second insulating adhesive layer M3 stacked sequentially. For ease of description below, ... Figure 2A coordinate system O-X0Z0 is established, where X0 is the direction of the bonding surface of the insulating adhesive layer 1052, and Z0 is the stacking direction of the composite layers in the insulating adhesive layer 1052. The bonding surface of the insulating adhesive layer 1052 is the surface used for bonding with other structures, and the X0 direction is perpendicular to the Z0 direction. It should be understood that the insulating adhesive layer 1052 is typically a sheet-like structure during use; therefore, the bonding surface of the insulating adhesive layer 1052 is the wide surface of the sheet-like structure, X0 is the direction of the wide surface of the sheet-like structure, and Z0 is the thickness direction of the sheet-like structure.

[0047] When an ESD current I0 along the Z0 direction is applied to the insulating adhesive layer 1052, the second insulating adhesive layer M3, the PET film layer M2, and the first insulating adhesive layer M1 need to be broken down sequentially to completely break down the insulating adhesive layer 1052. Since the PET film layer M2 has higher insulation performance than the insulating adhesive layer, the presence of the PET film layer M2 increases the difficulty of breaking down this path, thereby increasing the insulation performance of the insulating adhesive layer 1052 along the Z0 direction.

[0048] However, the insulating adhesive layer 1052 obtained by stacking the PET film layer M2 along the Z0 direction only increases the insulation performance along the Z0 direction, and its insulation performance along the X0 direction cannot be effectively guaranteed. Specifically, when an ESD current I1 along the X0 direction acts on the PET film layer M2 of the insulating adhesive layer 1052, the insulation performance of the insulating adhesive layer 1052 along the X0 direction depends on the PET film layer M2; when an ESD current I2 along the X0 direction acts on other locations besides the PET film layer M2 (such as the second insulating adhesive layer M3), the insulation performance of the insulating adhesive layer 1052 along the X0 direction mainly depends on the insulating adhesive layer (such as the second insulating adhesive layer M3), and the PET film layer M2 may completely lose its effectiveness. Therefore, for application scenarios where ESD current breaks down along the X0 direction (such as...), Figure 1c In the scenario shown, Figure 2 The insulating adhesive layer 1052 shown cannot provide effective protection against electrostatic discharge (ESD) for electronic devices.

[0049] Furthermore, because the insulating adhesive layer 1052 has a relatively large width along the X0 direction, when the PET film is laminated along the Z0 direction, the PET film layer M2 can form a strong bond with the first insulating adhesive layer M1 and the second insulating adhesive layer M3 respectively, thus forming a stable and reliable composite layer structure. However, because the insulating adhesive layer 1052 has a relatively small thickness along the Z0 direction, if the PET film is laminated along the X0 direction, it will not be able to form a good bond with the composite layers on both sides, resulting in the insulating adhesive layer 1052 being prone to delamination and having poor strength. In other words, the method of laminating PET film is suitable for increasing the insulation performance of the insulating adhesive layer 1052 along the Z0 direction, but it is not suitable for increasing the insulation performance of the insulating adhesive layer 1052 along the X0 direction.

[0050] Therefore, in order to improve the insulation performance of the insulating adhesive layer 1052 along the X0 direction, this application provides an insulating tape and an insulating adhesive. The following is in conjunction with... Figures 3 to 5 The insulating tape and insulating adhesive provided in the embodiments of this application will be described in detail.

[0051] Please see Figure 3 , Figure 3 This is a cross-sectional structural diagram of an insulating tape provided in some embodiments of this application. The insulating tape 00 includes a first thin film layer L1, an adhesive layer L2, and a second thin film layer L3 stacked sequentially.

[0052] The first film layer L1 and the second film layer L3 are used to adhere the adhesive layer L2. In actual use, the user can peel off the first film layer L1 and the second film layer L3 to use the adhesive layer L2 for double-sided bonding; of course, the user can also peel off either the first film layer L1 or the second film layer L3 to use the adhesive layer L2 for single-sided bonding. For example, the materials of the first film layer L1 and the second film layer L3 can be polyethylene terephthalate (PET), polyvinyl chloride (PVC), or polyethylene (PE).

[0053] The colloidal layer L2 is made of insulating adhesive 01. This insulating adhesive 01 includes an insulating colloid 10 and insulating particles 20 doped within the insulating colloid 10. The breakdown field strength of the insulating particles 20 is greater than that of the insulating colloid 10.

[0054] It should be noted that, Figure 3 The diagram illustrates the specific internal structure of the insulating adhesive 01 that forms the colloidal layer L2. This application embodiment will not provide a separate illustration of the insulating adhesive 01. For ease of description below, in... Figure 3 A coordinate system O-X1Z1 is established, where X1 is the direction of the bonding surface of the colloidal layer L2, and Z1 is the stacking direction of the first film layer L1, the colloidal layer L2, and the second film layer L3, and also the thickness direction of the colloidal layer L2. Furthermore, the X1, Y1, and Z1 directions illustrated in other figures in this embodiment can be referenced... Figure 3 The implementation of the corresponding directions will not be elaborated further.

[0055] Figure 3 In the insulating tape 00 shown, because the breakdown field strength of the insulating particles 20 is greater than that of the insulating colloid 10, the insulating performance of the insulating particles 20 is greater than that of the insulating colloid 10, and the insulating colloid 10 is more easily broken down than the insulating particles 20. When an ESD current along the X1 direction acts on... Figure 3 When the colloidal layer L2 is shown, the ESD current will break down the insulating colloidal layer 10, which has poorer insulation properties and is easier to break down, while bypassing the insulating particles 20, which have better insulation properties and are more difficult to break down. Figure 4 (a) in the figure illustrates the breakdown path of the ESD current along the X1 direction.

[0056] Please see Figure 4 , Figure 4 This is a comparison diagram showing the influence of insulating particles 20 on the ESD current breakdown path provided in some embodiments of this application. Figure 4 The insulating tape shown in (a) is Figure 3 The insulating tape 00 shown has an adhesive layer L2 made of insulating adhesive 01 doped with insulating particles 20. This differs from... Figure 4 (a) in the middle, Figure 4 In the insulating tape shown in (b), the colloidal layer L2 is composed of undoped material. Figure 4 The insulating particles 20 shown in (a) are made of insulating adhesive, that is, from Figure 4 The insulating colloid 10 shown in (a) is made of.

[0057] By comparison Figure 4 The breakdown path of the ESD current I3 (the thick line with arrows in the figure) in (a) and Figure 4 As can be seen from the breakdown path of the ESD current I4 in (b) (the thick line with arrows in the figure), the presence of insulating particles 20 lengthens the breakdown path of the ESD current. According to the differential formula for electric field strength... It can be seen that when the breakdown path becomes longer, the breakdown voltage required to break down the colloidal layer L2 along the X1 direction will increase. Therefore, the insulation performance of the colloidal layer L2 along the X1 direction is improved.

[0058] Furthermore, it should be understood that Figure 4 In (a) of the diagram, the insulating particles 20 within the colloidal layer L2 are doped along the entire Z1 direction. Therefore, regardless of where the ESD current I3 is applied to the colloidal layer L2 along the Z1 direction, its breakdown path is lengthened and is unaffected by the location of the application. In other words, compared to Figure 2 As shown in the insulating adhesive layer 1052, the insulating properties of the adhesive layer L2 along the X1 direction do not differ in the Z1 direction, resulting in more stable and reliable insulation performance.

[0059] It should be noted that, although Figure 4 (a) illustrates this with the ESD current I3 along the X1 direction. Figure 3 The insulation performance of the colloidal layer L2 along the X1 direction is improved, which should be understood. Figure 3The insulation performance along the Z1 direction is also improved, for a similar reason, which will not be elaborated here. In other words, the insulation performance of the colloidal layer L2 in this embodiment is improved in all directions during use.

[0060] For further information, please refer to [link / reference]. Figure 3 In some embodiments of this application, the insulating particles 20 are highly electronegative non-polar insulating particles, that is, the insulating particles 20 are both highly electronegative and non-polar insulating particles. It should be noted that the insulating particles 20 being highly electronegative means that the electronegativity of the insulating particles 20 is higher than that of the insulating colloid 10.

[0061] Exemplarily, the insulating colloid 10 is made of an organic insulating material. Exemplarily, the organic insulating material may include rubber or plastic. The rubber may include natural rubber or synthetic rubber, and the synthetic rubber may include nitrile rubber, silicone rubber, or styrene-butadiene rubber. The plastic may include thermoplastic plastics and thermosetting plastics; thermoplastic plastics may include acrylic acid, epoxy resin, or phenolic resin; thermosetting plastics may include acrylic acid, PE, PVC, or PET. In this case, the insulating material used to dope and form the insulating particles 20 includes tetrafluoroethylene and / or tetrafluoroethylene polymers.

[0062] The tetrafluoroethylene polymer may include one or more of polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, and perfluoropropyl perfluorovinyl ether-polytetrafluoroethylene copolymer.

[0063] It should be noted that many factors influence the breakdown field strength of the insulating particles 20, such as the material itself, electronegativity, and non-polarity. In other words, the high electronegativity and non-polarity of the insulating colloid 10 help increase the breakdown field strength of the insulating particles 20, thus contributing to a higher breakdown field strength than that of the insulating colloid 10. However, a higher breakdown field strength of the insulating particles 20 does not necessarily mean that the electronegativity of the insulating colloid 10 is higher than that of the insulating colloid 10, nor that the insulating particles 20 are necessarily non-polar. In some embodiments, even when the electronegativity of the insulating colloid 10 is lower than that of the insulating colloid 10, and / or the insulating particles 20 are polar, the breakdown field strength of the insulating particles 20 may still be higher than that of the insulating colloid 10. The electronegativity and non-polarity of the insulating particles 20 in this embodiment will be discussed separately below.

[0064] First, the electronegativity of insulating particles 20 represents their ability to adsorb electrons. When the electronegativity of insulating particles 20 is higher than that of insulating colloid 10, insulating particles 20 have high electronegativity. Compared to the case of low electronegativity, higher electronegativity gives them a stronger ability to adsorb electrons, thereby increasing the breakdown voltage of the dielectric surrounding insulating particles 20. The following section will discuss this further. Figure 5Analyze the specific reasons.

[0065] Please see Figure 5 , Figure 5 This is a schematic diagram illustrating the breakdown path of ESD current in the dielectric surrounding the insulating particle 20, provided in some embodiments of this application. For ease of illustration, Figure 5 The insulating particles 20 are not filled. It should be noted that the dielectric surrounding the insulating particles 20 falls into the following categories:

[0066] Case 1: The medium surrounding the insulating particle 20 is an air gap 30.

[0067] Please see Figure 5 In (a) of the diagram, when the insulating particle 20 and the insulating colloid 10 are not completely bonded, a small air gap 30 will exist between the insulating particle 20 and the insulating colloid 10 that encapsulates it. In this case, the medium surrounding the insulating particle 20 is the air gap 30, and the ESD current I5 continues to travel by breaking down this air gap 30. It should be understood that for ease of illustration, the size of the air gap 30 is enlarged in this diagram; in actual implementation, the size of the air gap 30 is much smaller than shown in the diagram.

[0068] The breakdown process of air gap 30 is an electron avalanche process. For details, please refer to... Figure 6 Electron N1 moves directionally under the influence of an electric field. When the electric field strength is strong enough, electron N1 will be accelerated and collide with neutral air molecules, ionizing into a new electron N2 and a new ion (not shown in the figure). Similarly, electrons N1 and N2 collide with neutral air molecules under the influence of the electric field. Electron N1 ionizes into a new electron N3 and a new ion (not shown in the figure), while electron N2 ionizes into a new electron N4 and a new ion (not shown in the figure). This process continues, producing even more electrons and ions, resulting in an avalanche-like increase in the number of electrons and ions. Please continue reading. Figure 5 When the electron avalanche process within the air gap 30 is strong enough, resulting in a sufficient number of ions in the air gap 30, the air gap 30 will be broken down.

[0069] In this embodiment, because the insulating particles 20 have a higher electron adsorption capacity, a large number of electrons are adsorbed by the surface of the insulating particles 20, reducing the number of electrons in the air gap 30. As the number of electrons in the air gap 30 decreases, the collisional ionization phenomenon in the air gap 30 weakens, resulting in a sharp decrease in the number of ions in the air gap 30, making it difficult to break down. It should be understood that the stronger the electric field strength, the stronger the aforementioned collisional ionization phenomenon, and thus the greater the number of electrons and ions in the air gap 30. Based on this, in order to break down the air gap 30 surrounding the insulating particles 20, it is necessary to increase the electric field strength. According to the field strength formula, with the gap remaining constant, a stronger breakdown voltage is required.

[0070] Scenario 2: The medium surrounding the insulating particle 20 is the insulating colloid 10.

[0071] Please see Figure 5 In (b), when the insulating particles 20 are completely bonded to the insulating colloid 10, the insulating colloid 10 tightly wraps the insulating particles 20. In this case, the medium around the insulating particles 20 is the insulating colloid 10, and the ESD current I6 will break down the insulating colloid 10 and continue to travel.

[0072] Different from Figure 5 The breakdown of the air gap 30 shown in (a) is a solid-state breakdown of the insulating colloid 10. The breakdown process is as follows: When the electric field strength is sufficiently high, electrons N1 move directionally under the influence of the electric field, moving from one potential well to another, thus colliding with the solid molecules of the insulating colloid 10 and generating an electron avalanche process within the insulating colloid 10. This process is similar to that occurring in the air gap 30 and will not be elaborated further here. Similarly, when the insulating particles 20 have a higher electron adsorption capacity, a large number of electrons are adsorbed on the surface of the insulating particles 20, reducing the number of electrons in the insulating colloid 10 surrounding the insulating particles 20. As the number of electrons decreases, the collisional ionization in the insulating colloid 10 surrounding the insulating particles 20 weakens, resulting in a sharp decrease in the number of ions in the insulating colloid 10 surrounding the insulating particles 20, making it difficult to break down. Based on this, a stronger breakdown voltage is required to break down the insulating colloid 10 surrounding the insulating particles 20.

[0073] In summary, based on the information from scenarios one and two, when ESD current flows through the medium surrounding the insulating particle 20, the presence of the more electronegative insulating particle 20 necessitates a stronger breakdown voltage to break down the surrounding medium. Therefore, Figure 3 The insulation performance of the insulating adhesive 01 (i.e., the adhesive layer L2) shown is improved.

[0074] In addition, please continue to refer to Figure 3When the insulating particles 20 are non-polar, it indicates low polarizability, meaning they are not easily polarized under an electric field. Compared to the case where the insulating particles 20 are polar, the non-polar insulating particles 20 will not reduce the breakdown voltage of the insulating adhesive 01, thus not reducing the insulation performance of the insulating adhesive 01. The following will combine... Figure 7 Analyze the specific reasons.

[0075] Please see Figure 7 , Figure 7 This diagram illustrates the polarization of polar molecules under the influence of an electric field. Figure 7 It can be observed that polarized molecules are polarized under the influence of an external electric field E0, thus exhibiting a state where one end is positively charged and the other end is negatively charged. An internal electric field E1, in the same direction as the external electric field E0, will be formed between pairs of adjacent polar molecules.

[0076] For details regarding this embodiment, please refer to the following: Figure 3 When the ESD current breaks down the colloidal layer L2 along the X1 direction, the direction of the external electric field E0 is the X1 direction. When the insulating particles 20 are polar, an internal electric field E1 will be generated between each pair of adjacent insulating particles 20, in the same direction as the breakdown field strength, i.e., an internal electric field E1 in the X1 direction. In this case, the total electric field of the colloidal layer L2 along the X1 direction is the sum of the internal electric field E1 and the external electric field E0, making the colloidal layer L2 more prone to breakdown and weakening the insulation performance of the colloidal layer L2 along the X1 direction. When the insulating particles 20 are non-polar, no internal electric field E1 will be generated, thus not weakening the insulation performance of the colloidal layer L2 along the X1 direction.

[0077] As can be seen from the above analysis, the electronegativity and non-polarity of the insulating particles 20 both contribute to ensuring the insulation performance of the colloidal layer L2. Based on this, the concept of electronegativity and non-polarity of the insulating particles 20 can be implemented in separate embodiments. In some embodiments, the electronegativity of the insulating particles 20 is higher than that of the insulating colloid 10, without requiring the insulating particles 20 to be non-polar. In this case, the material of the insulating particles 20 may include vinylidene fluoride polymers, vinylidene fluoride copolymers, trifluorochloroethylene polymers, or trifluorochloroethylene copolymers. In other embodiments, the insulating particles 20 are non-polar, without requiring the electronegativity of the insulating particles 20 to be higher than that of the insulating colloid 10. In this case, the insulating particles 20 can be made of a material among the aforementioned organic insulating materials whose breakdown field strength is greater than that of the insulating colloid 10. This application does not specifically limit this aspect.

[0078] Please refer to some embodiments of this application. Figure 3To ensure the strength and adhesion of the colloidal layer L2, the diameter of the insulating particle 20 is less than or equal to one-tenth of the diameter of the colloidal layer L2. For example, the diameter of the insulating particle 20 can be one-tenth or one-eleventh of the diameter of the colloidal layer L2.

[0079] It should be understood that the diameter of the insulating particles 20 should not be too large. If the diameter of the insulating particles 20 is too large, the non-adhesive insulating particles 20 distributed on the surface of the colloid layer L2 will result in too low surface adhesion of the colloid layer L2; the non-adhesive insulating particles 20 distributed within the colloid layer L2 will not easily adhere to the insulating colloid 10, resulting in lower overall strength of the colloid layer L2. Furthermore, the insulating colloid 10 between pairs of insulating particles 20 will be relatively thin, making the colloid layer L2 prone to cracking in the Z1 direction.

[0080] Please refer to other embodiments of this application. Figure 3 To ensure the strength and adhesion of the colloid layer L2, the mass ratio of insulating particles 20 to insulating colloid 10 is 30% to 60%. For example, the mass ratio of insulating particles 20 to insulating colloid 10 is 30%, 45%, 50%, 55%, or 60%.

[0081] It should be understood that the doping ratio of insulating particles 20 should not be too high or too low. Since insulating particles 20 do not possess adhesive properties, a high doping ratio will reduce the adhesiveness and strength of the insulating adhesive. A low doping ratio will not significantly improve the insulating properties of the adhesive. In this embodiment, the mass ratio of insulating particles 20 to insulating adhesive 10 is controlled to be between 30% and 60%. This ensures both the adhesiveness and strength of the insulating adhesive, as well as its insulating properties.

[0082] It should be noted that, Figure 3 The following description uses an insulating tape 00 comprising two film layers as an example. In other embodiments, the insulating tape 00 may also comprise only one film layer. Please refer to... Figure 8 The insulating tape 00 includes a first film layer L1 and an adhesive layer L2. The adhesive layer L2 is laminated on the first film layer L1. Specific implementations of the first film layer L1 and the adhesive layer L2 can be found in [reference needed]. Figure 3 The relevant details shown will not be repeated here. In actual production, this insulating tape 00 can be produced by wrapping, similar to the wrapping method of transparent tape on the market. In actual use, the user can peel off the first film layer L1 and use the adhesive layer L2 for double-sided bonding; of course, the user can also directly use the adhesive layer L2 with the first film layer L1 for single-sided bonding.

[0083] In order to obtain the insulating adhesive shown in the above embodiments, this application also provides a method for preparing the insulating adhesive.

[0084] Please see Figure 9 The preparation method of this insulating adhesive includes:

[0085] S901 processes insulating colloids to a molten state.

[0086] S902, insulating particles are incorporated into molten insulating colloid and mixed to obtain insulating colloid to be treated; wherein the breakdown field strength of the insulating particles is greater than that of the insulating colloid, and the insulating particles are highly electronegative nonpolar insulating particles.

[0087] S903 involves cooling the insulating adhesive to be treated.

[0088] S904, to obtain insulating adhesive.

[0089] In practice, depending on the type of insulating adhesive, after cooling, further processing can be performed to obtain the desired insulating adhesive. For example, if the insulating adhesive is foam adhesive, foaming can be performed after S903 and before S904, followed by shaping to obtain the insulating adhesive. If the insulating adhesive is not foam adhesive, shaping can be performed directly after S903 and before S904 to obtain the insulating adhesive. It should be noted that the material and mass ratio of the insulating adhesive and insulating particles, as well as the diameter of the insulating particles, are already specified in the specifications. Figure 3 The relevant embodiments have been described in detail, and can be referred to the embodiments, which will not be repeated here.

[0090] The above description is merely a specific implementation of the embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the embodiments of this application should be covered within the protection scope of the embodiments of this application. Therefore, the protection scope of the embodiments of this application should be determined by the protection scope of the claims.

Claims

1. A housing assembly, characterized in that, For protecting a camera module in an electronic device, the camera module is located on one side of the housing assembly, the housing assembly includes: a rear shell and a camera bracket mounted on the rear shell, the camera bracket and the housing having a gap; An insulating tape is attached to the back cover, and the insulating tape is located between the back cover and the camera module, so as to isolate the gap from the camera module. The insulating tape includes: An insulating colloid and insulating particles, wherein the insulating particles are doped into the insulating colloid; wherein the breakdown field strength of the insulating particles is greater than that of the insulating colloid, and the insulating particles are highly electronegative nonpolar insulating microparticles, and the electronegativity of the insulating particles is greater than that of the insulating colloid. The mass ratio of the insulating particles to the insulating colloid is 45% to 60%. The insulating material of the insulating particles includes a tetrafluoroethylene polymer, which is selected from one or more of tetrafluoroethylene-hexafluoropropylene copolymer and perfluoropropyl perfluorovinyl ether-polytetrafluoroethylene copolymer.

2. The housing assembly according to claim 1, characterized in that, The mass ratio of the insulating particles to the insulating colloid is 45%, 50%, 55%, or 60%.

3. The housing assembly according to claim 1 or 2, characterized in that, The insulating colloid is made of rubber or plastic.

4. The housing assembly according to claim 3, characterized in that, The rubber includes nitrile rubber, silicone rubber, or styrene-butadiene rubber; The plastics include epoxy resin, phenolic resin, PE, PVC, or PET.

5. The housing assembly according to any one of claims 1 to 4, characterized in that, The insulating tape includes an insulating film and an insulating adhesive layer. The two ends of the insulating film are bonded to the back cover through the insulating adhesive layer. The insulating film and the insulating adhesive layer together isolate the gap from the camera module.

6. The housing assembly according to claim 5, characterized in that, The insulating adhesive layer includes: A first thin film layer and a colloidal layer, wherein the first thin film layer is adhered to one side of the colloidal layer.

7. The housing assembly according to claim 6, characterized in that, The insulating adhesive layer further includes: Second thin film layer; The second film layer adheres to the side of the colloidal layer away from the first film layer.

8. The housing assembly according to claim 6 or 7, characterized in that, The diameter of the insulating particles is less than or equal to one-tenth of the thickness of the colloidal layer.

9. An electronic device, characterized in that, The device includes a camera module and a housing assembly as described in any one of claims 1-8, wherein the camera module is disposed on one side of the housing assembly, and the housing assembly is used to protect the camera module.

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