Waterproofing member

Abstract

This waterproofing member 10 is disposed so as to block an opening 51 of an object 50 that has an opening surface 51s where the opening 51 is formed. The waterproofing member 10 comprises a waterproofing film 1 that has a first principal surface 1a which faces the opening 51 when arranged so as to block the opening 51, and a second principal surface 1b which is on the opposite side from the first principal surface 1a. The waterproofing film 1 includes a body part 11 and particles 12 positioned more on the first principal surface 1a side than the body part 11. The first principal surface 1a of the waterproofing film 1 has a region R1a in which the arithmetic average height Sa is 0.20 μm or greater. The object 50 includes, for example, a micro-electromechanical system (MEMS).

Description

Waterproofing materials

[0001] The present invention relates to a waterproof member.

[0002] Electronic devices equipped with acoustic components (acoustic components) such as sound-generating units such as speakers and buzzers, and sound-receiving units such as microphones, include many portable devices used outdoors, such as wearable devices including smartwatches, smartphones, mobile phones, and digital cameras. In recent years, there has been a demand for electronic devices equipped with such acoustic components to be waterproof while maintaining sound transmission characteristics. Waterproof smartwatches and waterproof smartphones are already widespread, and filters (waterproof sound-transmitting members) with waterproof sound transmission capabilities are used to protect the acoustic parts (acoustic components) of these devices.

[0003] Conventionally, the use of a microporous membrane using polytetrafluoroethylene (PTFE) or the like has been proposed as a waterproof sound-transmitting member (see, for example, Patent Document 1).More recently, a waterproof protective cover member (waterproof member) that is placed over the opening of a micro-electromechanical system (MEMS) or other fine product has been proposed (see, for example, Patent Document 2).

[0004] Special table 2003-503991 publication Special table 2018-501972 publication

[0005] When pressure such as water pressure is applied to a waterproofing member that is arranged to close an opening in a device or the like having an opening formed on its surface, the waterproofing film (waterproof film) deforms. The deformation of the waterproof film due to the application of pressure can reduce the sound transmission characteristics of the waterproofing member.

[0006] Therefore, an object of the present invention is to provide a waterproof member that is suitable for suppressing a decrease in sound transmission characteristics caused by deformation of a waterproof membrane due to the application of pressure.

[0007] The present invention provides a waterproof member that is arranged to block an opening of an object having an opening surface on which an opening is formed, the waterproof member comprising a waterproof membrane having a first main surface facing the opening and a second main surface opposite the first main surface when arranged to block the opening, the waterproof membrane including a main body and particles located closer to the first main surface than the main body, and the first main surface of the waterproof membrane having a region having an arithmetic mean height of 0.20 μm or more.

[0008] From another aspect, the present invention provides a waterproof member that is arranged to close the opening inside a microelectromechanical system (MEMS) that includes a substrate having an opening that functions as a sound vent, a MEMS die having a vibration plate, and a cap that covers the MEMS die, the waterproof member comprising: a waterproof membrane that, when arranged to close the opening, has a first main surface facing the vibration plate and a second main surface opposite to the first main surface; the waterproof membrane includes a main body portion and particles that are located closer to the first main surface than the main body portion; and the first main surface of the waterproof membrane has a region where the arithmetic mean height is 0.20 μm or more.

[0009] From yet another aspect, the present invention provides a waterproof member that is arranged to close an opening of an object having an opening surface on which an opening is formed, the waterproof member comprising a waterproof membrane having a first main surface and a second main surface opposite to the first main surface, the waterproof membrane including a main body portion and particles located closer to the first main surface than the main body portion, the first main surface of the waterproof membrane having a region having an arithmetic mean height of 0.20 μm or more, and when arranged to close the opening, the first main surface or the second main surface of the waterproof membrane faces the opening.

[0010] According to the present invention, it is possible to provide a waterproof member that is suitable for suppressing a decrease in sound transmission characteristics caused by deformation of a waterproof membrane due to application of pressure.

[0011] FIG. 1 is a cross-sectional view schematically showing an example of a waterproof member according to a first embodiment of the present invention. FIG. 2 is a perspective view schematically showing the waterproof member of FIG. 1. FIG. 3 is a cross-sectional view schematically showing an example of a state in which the waterproof member of FIG. 1 is arranged to block an opening of an object. FIG. 4A is a cross-sectional view schematically showing an example of a waterproof membrane provided in the waterproof member of FIG. 1. FIG. 4B is a partially enlarged view of FIG. 4A. FIG. 5 is a cross-sectional view schematically showing deformation of the waterproof membrane when water pressure is applied to the waterproof member in the state of FIG. 3. FIG. 6 is a cross-sectional view schematically showing another example of the waterproof membrane provided in the waterproof member of FIG. 1. FIG. 7 is a cross-sectional view schematically showing another example of a waterproof member of the present invention. FIG. 8 is a perspective view schematically showing the waterproof member of FIG. 7. FIG. 9 is a cross-sectional view schematically showing an example of a state in which the waterproof member of FIG. 7 is arranged to block an opening of an object. FIG. 10 is a cross-sectional view schematically showing deformation of the waterproof membrane when water pressure is applied to the waterproof member in the state of FIG. 7. FIG. 11 is a cross-sectional view schematically showing an example of a waterproof member according to a second embodiment of the present invention. FIG. 12 is a cross-sectional view showing the configuration of a waterproofing member used in Examples and Comparative Examples. FIG. 13 is a schematic diagram illustrating a method for evaluating the insertion loss of a waterproofing member. FIG. 14A is a diagram (10,000x magnification) showing the results of scanning electron microscope (SEM) observation of the first main surface of the waterproofing membrane provided in the waterproofing member of Example 2. FIG. 14B is a diagram (1,000x magnification) showing the results of SEM observation of the first main surface of the waterproofing membrane provided in the waterproofing member of Example 2. FIG. 15A is a diagram (10,000x magnification) showing the results of SEM observation of the first main surface of the waterproofing membrane provided in the waterproofing member of Example 3. FIG. 15B is a diagram (1,000x magnification) showing the results of SEM observation of the first main surface of the waterproofing membrane provided in the waterproofing member of Example 3. FIG. 16A is a diagram (10,000x magnification) showing the results of SEM observation of the first main surface of the waterproofing membrane provided in the waterproofing member of Example 4. Fig. 16B is a diagram (1000x magnification) showing the results of SEM observation of a first main surface of the waterproof film provided in the waterproof member of Example 4. Fig. 17A is a diagram (10,000x magnification) showing the results of SEM observation of a first main surface of the waterproof film provided in the waterproof member of Example 5. Fig. 17B is a diagram (1000x magnification) showing the results of SEM observation of the first main surface of the waterproof film provided in the waterproof member of Example 5.

[0012] A waterproof member according to a first aspect of the present invention is a waterproof member that is arranged to block an opening of an object having an opening surface on which an opening is formed, and that, when arranged to block the opening, comprises a waterproof membrane having a first main surface facing the opening and a second main surface opposite the first main surface, the waterproof membrane including a main body portion and particles located closer to the first main surface than the main body portion, and the first main surface of the waterproof membrane has a region having an arithmetic mean height of 0.20 μm or more.

[0013] In a second aspect of the present invention, for example, in the waterproof member according to the first aspect, the object includes a microelectromechanical system (MEMS).

[0014] In a third aspect of the present invention, for example, in the waterproof member according to the first or second aspect, the particles in the region of the first main surface have an average particle size in the range of 0.2 μm to 5 μm.

[0015] In a fourth aspect of the present invention, for example, in the waterproof member according to any one of the first to third aspects, the waterproof film further includes a coating layer that covers at least a part of the surface of the particle.

[0016] In a fifth aspect of the present invention, for example, in the waterproof member according to any one of the first to fourth aspects, the arithmetic mean height of the region on the first main surface is less than 1 μm.

[0017] In a sixth aspect of the present invention, for example, in a waterproof member according to any one of the first to fifth aspects, the difference in insertion loss for a sound with a frequency of 1 kHz before and after a water pressure application test in which a water pressure of 0.5 MPa is applied to the second main surface of the waterproof membrane for 10 minutes is 2.5 dB or less.

[0018] In a seventh aspect of the present invention, for example, in the waterproof member according to any one of the first to sixth aspects, the main body portion of the waterproof membrane is a non-porous membrane.

[0019] In an eighth aspect of the present invention, for example, in a waterproof member according to any one of the first to seventh aspects, the main body portion of the waterproof membrane includes at least one selected from the group consisting of silicone rubber, polyurethane, polyethylene terephthalate, polyimide, and polytetrafluoroethylene.

[0020] In a ninth aspect of the present invention, for example, in the waterproof member according to any one of the first to eighth aspects, the main body portion of the waterproof membrane includes an elastomer.

[0021] In a tenth aspect of the present invention, for example, in a waterproof member according to any one of the first to ninth aspects, when the waterproof member is positioned to block the opening, the first main surface of the waterproof membrane and the opening surface face each other via a space that contacts the first main surface and the opening surface.

[0022] In an eleventh aspect of the present invention, for example, the waterproof member according to any one of the first to tenth aspects further includes a pressure-sensitive adhesive layer bonded to the first main surface of the waterproof membrane.

[0023] In a twelfth aspect of the present invention, for example, a waterproof member according to any one of the first to eleventh aspects further comprises a support layer that is spaced apart from the waterproof membrane and has breathability in the thickness direction, and the support layer is positioned between the waterproof membrane and the object when the waterproof member is positioned to block the opening.

[0024] In a thirteenth aspect of the present invention, for example, in the waterproof member according to the twelfth aspect, the support layer has a first main surface facing the opening and a second main surface opposite the first main surface when the waterproof member is positioned to block the opening, and the waterproof member further comprises a bonding layer that bonds the first main surface of the waterproof membrane to the second main surface of the support layer, and a pressure-sensitive adhesive layer bonded to the first main surface of the support layer.

[0025] A waterproof member according to a fourteenth aspect of the present invention is a waterproof member that is arranged to cover the opening inside a microelectromechanical system (MEMS) that includes a substrate having an opening that functions as a sound vent, a MEMS die having a vibration plate, and a cap that covers the MEMS die, and when arranged to cover the opening, it comprises a waterproof membrane that has a first main surface facing the vibration plate and a second main surface opposite to the first main surface, the waterproof membrane including a main body portion and particles located closer to the first main surface than the main body portion, and the first main surface of the waterproof membrane has a region having an arithmetic mean height of 0.20 μm or more.

[0026] A waterproof member according to a fifteenth aspect of the present invention is a waterproof member that is arranged to block an opening of an object having an opening surface on which an opening is formed, and comprises a waterproof membrane having a first main surface and a second main surface opposite to the first main surface, the waterproof membrane including a main body portion and particles located closer to the first main surface than the main body portion, the first main surface of the waterproof membrane having a region having an arithmetic mean height of 0.20 μm or more, and when arranged to block the opening, the first main surface or the second main surface of the waterproof membrane faces the opening.

[0027] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings, but is not limited to the following embodiments.

[0028] First Embodiment An example of a waterproof member according to a first embodiment is shown in FIGS. 1 and 2. The waterproof member 10 shown in FIGS. 1 and 2 includes a waterproof membrane 1. As shown in FIG. 3, the waterproof member 10 is used by being disposed so as to cover an opening 51 of an object 50 having an opening surface 51s on which the opening 51 is formed. In this specification, the term "opening surface" refers to a surface on which an opening is formed, i.e., a surface having an opening. The object 50 includes, for example, products such as acoustic equipment and microelectromechanical systems (MEMS). The object 50 may also be a MEMS.

[0029] The waterproof membrane 1 is a membrane that prevents water from entering while allowing sound to pass through. The waterproof membrane 1 has a shape that blocks the opening 51. The waterproof membrane 1 has a first main surface 1a and a second main surface 1b opposite the first main surface 1a. As shown in FIG. 3 , in the first embodiment, when the waterproof membrane 1 is arranged to block the opening 51, the first main surface 1a of the waterproof membrane 1 faces the opening 51. In this specification, "facing the opening" means facing the opening side, and is not limited to cases where two members face each other, but also includes cases where another member exists between the two members. In this specification, the "main surface" means the surface of the sheet-like member that has the largest area.

[0030] As shown in Figure 3, when the waterproof member 10 is positioned to block the opening 51, the first main surface 1a of the waterproof membrane 1 and the opening surface 51s face each other via a space that is in contact with the first main surface 1a and the opening surface 51s.

[0031] 1 and 2, the waterproof member 10 further includes a pressure-sensitive adhesive layer 2 bonded to the first main surface 1a of the waterproof membrane 1. In this embodiment, the pressure-sensitive adhesive layer 2 is disposed on the peripheral portion of the first main surface 1a of the waterproof membrane 1. Note that the reference numeral 4 in Fig. 2 indicates a region that transmits sound when the waterproof member 10 is installed in a device, i.e., a sound-transmitting region (sound-passing region).

[0032] As shown in Fig. 1 , the first main surface 1a of the waterproof membrane 1 has an exposed region where the adhesive layer 2 is not present. Hereinafter, the exposed region will be referred to as an exposed region 10a. As shown in Fig. 3 , when the waterproof member 10 is arranged to cover the opening 51, the waterproof member 10 has an overlapping region 10b where the exposed region 10a and the opening surface 51s overlap when viewed from a direction perpendicular to the main surface of the waterproof membrane 1.

[0033] Fig. 4A is a cross-sectional view schematically illustrating an example of the waterproof membrane 1 included in the waterproof member 10. As shown in Fig. 4A, in this embodiment, the waterproof membrane 1 includes a main body 11 and particles 12 located closer to the first main surface 1a than the main body 11. As shown in Fig. 1, the first main surface 1a of the waterproof membrane 1 has a region R1a where the arithmetic mean height Sa is 0.20 µm or more. The region R1a corresponds to, for example, the exposed region 10a.

[0034] In this specification, the term "particle" refers not only to a single particle but also to an aggregate of multiple particles. Therefore, when "particle" in this specification refers to an aggregate of multiple particles, the term "particle" can be rephrased as "powder."

[0035] When pressure such as water pressure is applied to the waterproof member 10 placed on the object 50 from the second main surface 1b of the waterproof membrane 1, the waterproof membrane 1 deforms and distorts toward the opening 51s. This phenomenon will be described with reference to FIG. 5. FIG. 5 is a schematic cross-sectional view illustrating the deformation of the waterproof membrane 1 when water pressure p is applied to the waterproof member 10 in the state shown in FIG. 3. As shown in FIG. 5, when water pressure p is applied to the waterproof member 10 from the outside (second main surface 1b) of the object 50 (FIG. 5A), the waterproof membrane 1 deforms and is pressed against the opening 51s (FIG. 5B). In conventional waterproof members, the deformation of the waterproof membrane sometimes persists without recovering even after the water pressure p is released. This continued deformation of the waterproof membrane reduces the sound transmission characteristics of the waterproof member.

[0036] Therefore, the inventors of the present invention have conducted extensive research into methods for suppressing the deterioration of the sound transmission characteristics of the waterproofing member, and have come up with the idea of ​​focusing on the structure of the first main surface (the main surface facing the opening) of the waterproofing membrane.

[0037] In a waterproof member 10 in which the waterproof membrane 1 includes a main body 11 and particles 12 located closer to the first main surface 1a than the main body 11, and the first main surface 1a of the waterproof membrane 1 has a region R1a with an arithmetic mean height Sa of 0.20 μm or more, the contact area between the first main surface 1a and the opening 51s can be reduced when the waterproof membrane 1 is deformed by being pressed against the opening 51s due to the application of pressure such as water pressure (see FIG. 5B). As a result, after the pressure is released, the first main surface 1a of the waterproof membrane 1 easily separates from the opening 51s and returns to its original shape. In other words, the deformation of the waterproof membrane 1 is easily restored. Therefore, the waterproof member 10 of this embodiment is suitable for suppressing deterioration of sound transmission characteristics.

[0038] One surface of the main body 11 located on the first main surface 1a side of the waterproof membrane 1 is defined as the first surface 11a of the main body 11, and the other surface of the main body 11 located on the first main surface 1b side of the waterproof membrane 2 is defined as the second surface 11b of the main body 11. In this case, as shown in Fig. 4A, particles 12 may be present on the first surface 11a of the main body 11. All of the particles 12 may be attached to the first surface 11a of the main body 11.

[0039] 1, the region R1a corresponds to the entire first main surface 1a. That is, the entire first main surface 1a of the waterproof membrane 1 satisfies the requirement that the arithmetic mean height Sa is 0.20 μm or more. With this configuration, the above-described effects of the waterproof member 10 of the embodiment can be more easily achieved.

[0040] However, the position of region R1a is not limited to the example shown in Fig. 1. Fig. 6 is a cross-sectional view schematically showing another example of the waterproof membrane 1 provided in the waterproof member 10. In the waterproof member 10A shown in Fig. 6, region R1a corresponds to the exposed region 10a. That is, the arithmetic mean height Sa in the exposed region 10a is 0.20 µm or more. As shown in Fig. 6, region R1a may correspond to the exposed region 10a. Even with such a configuration, the above-described effects of the waterproof member 10 of this embodiment can be obtained.

[0041] Although not shown, the region R1a may correspond to the overlap region 10b (see FIG. 3). That is, the arithmetic mean height Sa in the overlap region 10b may be 0.20 μm or more. Even with such a configuration, the above-described effects of the waterproofing member 10 of this embodiment can be obtained.

[0042] The lower limit of the arithmetic mean height Sa of the region R1a of the first main surface 1a may be 0.25 μm.

[0043] The arithmetic mean height Sa of the region R1a of the first principal surface 1a may be less than 1 μm. When the arithmetic mean height Sa of the region R1a is less than 1 μm, for example, even when the region R1a corresponds to the entire first principal surface 1a, the bonding between the first principal surface 1a of the waterproof membrane 1 and the pressure-sensitive adhesive layer 2 is less likely to be hindered.

[0044] The upper limit of the arithmetic mean height Sa of the region R1a of the first main surface 1a may be 0.90 μm, 0.80 μm, 0.70 μm, or even 0.65 μm.

[0045] (Method for measuring arithmetic mean height Sa of waterproof membrane) The arithmetic mean height Sa of the region R1a of the first main surface 1a of the waterproof membrane 1 can be measured in accordance with the non-contact (optical probe) evaluation method of ISO 25178. Specifically, the arithmetic mean height Sa of the region R1a of the first main surface 1a can be measured using a shape analysis laser microscope (for example, VK X260 manufactured by Keyence Corporation) at an observation magnification of 160 times. The arithmetic mean height Sa of the second main surface 1b of the waterproof membrane 1 can also be measured in a similar manner.

[0046] The waterproof member 10 has a difference in insertion loss IL for a sound with a frequency of 1 kHz before and after a water pressure application test in which a water pressure of 0.5 MPa is applied to the second main surface 1b of the waterproof membrane 1 for 10 minutes. D The difference in insertion loss for a sound with a frequency of 1 kHz is IL D is 2.5 dB or less means that the difference in insertion loss IL D does not exceed 2.5 dB.

[0047] In the waterproof member 10, the waterproof film 1 includes a main body 11 and particles 12 located closer to the first main surface 1a than the main body 11, and the first main surface 1a of the waterproof film 1 has a region R1a where the arithmetic mean height Sa is 0.20 μm or more. D The difference in insertion loss IL of the waterproofing member 10 is suppressed to 2.5 dB or less. In other words, the deterioration of the sound transmission characteristics is suppressed. D The lower limit of the difference in insertion loss IL D The lower limit is, for example, 0 dB.

[0048] (Method of Measuring Insertion Loss of Waterproofing Member) Details of the method of measuring the insertion loss of the waterproofing member 10 for a sound with a frequency of 1 kHz will be described in the section of Examples.

[0049] The thickness of the waterproof membrane 1 is, for example, 1 μm or more and 100 μm or less. When the thickness of the waterproof membrane 1 is within this range, sound transmission characteristics can be improved while ensuring sufficient waterproofness and strength. Generally, the thinner the waterproof membrane 1, the more easily the waterproof membrane 1 tends to deform. As described above, the sound transmission characteristics of the waterproof member 10 may be reduced due to deformation of the waterproof membrane 1. However, in the waterproof member 10 of this embodiment, the waterproof membrane 1 is easily restored from deformation, so the reduction in sound transmission characteristics due to continued deformation is suppressed. Therefore, by making the thickness of the waterproof membrane 1 relatively small, at 100 μm or less, sound transmission characteristics can be improved.

[0050] The upper limit of the thickness of the waterproof membrane 1 may be 90 μm, 80 μm, 70 μm, or even 60 μm, and the lower limit of the thickness of the waterproof membrane 1 may be 3 μm or 5 μm.

[0051] (Method of measuring the thickness of the waterproof membrane) The thickness of the waterproof membrane 1 can be determined by measuring the thickness at any five points on the waterproof membrane 1 using, for example, a dial gauge, and calculating the average value of these measurements. The thickness of the waterproof membrane 1 can also be determined by measuring the thickness at any five points on an image of a cross section of the waterproof membrane 1 observed with a scanning electron microscope (SEM) and calculating the average value of these measurements. The thicknesses of other members can also be determined in a similar manner.

[0052] The average particle size of the particles 12 in the region R1a of the first main surface 1a is preferably in the range of 0.2 μm to 5 μm. This range can be achieved, for example, by arranging particles 12 with an average particle size in the range of 0.2 μm to 5 μm closer to the first main surface 1a than the main body 11. Particles 12 with an average particle size in the range of 0.2 μm to 5 μm have high dispersibility. This allows the particles 12 to be more uniformly arranged closer to the first main surface 1a than the main body 11. Therefore, in a waterproof membrane 1 in which the average particle size of the particles 12 in the region R1a is in the range of 0.2 μm to 5 μm, the particles 12 are more uniformly present in the region R1a, which makes it easier to reduce the contact area between the first main surface 1a and the opening surface 51s when the waterproof membrane 1 is deformed by being pressed against the opening surface 51s due to the application of pressure such as water pressure.

[0053] The lower limit of the average particle size of the particles 12 in the region R1a of the first main surface 1a may be 0.3 μm, 0.4 μm, or even 0.5 μm. The upper limit of the average particle size of the particles 12 in the region R1a may be 4.5 μm, 4.0 μm, 3.5 μm, 3.0 μm, 2.5 μm, or even 2.0 μm.

[0054] (Method for measuring average particle size) The average particle size of the particles 12 in the region R1a of the first main surface 1a of the waterproof membrane 1 can be determined from a surface SEM image obtained by observing the region R1a of the first main surface 1a of the waterproof membrane 1 with an SEM. In the surface SEM image, the equivalent diameter of any number of particles 12 (at least 50 particles) is measured. The average value of the equivalent diameters can be considered to be the average particle size of the particles 12. The equivalent diameter means the diameter of a circle having the same area. The average particle size of the particles 12 as raw material powder is the particle size (D50) corresponding to 50% of the cumulative volume from the smaller particle size side in the particle size distribution of the particles 12 measured based on a laser diffraction / scattering method.

[0055] There are no particular limitations on the raw material of the particles 12. Examples of the raw material of the particles 12 include silicone rubber, silicone resin, silica, and metal oxides such as aluminum oxide, zirconium oxide, and titanium oxide. As the raw material of the particles 12, one or a combination of two or more selected from these may be used.

[0056] The particles 12 may have a coating layer that covers at least a portion of the surface. That is, the particles 12 may be a composite in which at least a portion of the surface is covered with a coating layer. The raw material of the coating layer is not particularly limited. The raw materials of the particles 12 may be used as the raw materials of the coating layer. The coating layer may contain, for example, a silicone resin.

[0057] The particles 12 may contain at least one selected from the group consisting of silicone rubber, silicone resin, and silica. The particles 12 may contain at least one selected from the group consisting of silicone rubber, silicone resin, and silica as a main component. The waterproof membrane 1 may consist of only at least one selected from the group consisting of silicone rubber, silicone resin, and silica. In this specification, "main component" means the component that is contained in the largest amount by mass. The same applies to other raw materials.

[0058] The particles 12 may be a composite in which at least a portion of the surface of a silicone rubber particle is coated with a silicone resin. The particles 12 may be silicone resin particles or silica particles.

[0059] The shape of the particles 12 is not particularly limited as long as the arithmetic mean height Sa of the region R1a of the first main surface 1a can be 0.20 μm or greater. Examples of the shape of the particles 12 include spherical, plate-like, and needle-like shapes. The particles 12 may be spherical. If the particles 12 are spherical, the contact area between the first main surface 1a and the opening surface 51s can be further reduced when the waterproof membrane 1 is deformed by being pressed against the opening surface 51s due to the application of pressure such as water pressure. This makes it easier for the waterproof membrane 1 to recover from deformation.

[0060] 4A , the waterproof membrane 1 may further include a coating layer 13 that covers at least a portion of the surface 12s of the particles 12. That is, the waterproof membrane 1 may include a main body 11, the particles 12, and the coating layer 13. The coating layer 13 contributes to improving the adhesion between the first surface 11a of the main body 11 and the particles 12. Therefore, for example, the particles 12 are prevented from falling off from the first surface 11a of the main body 11. The coating layer 13 may cover the entire surface 12s of the particles 12.

[0061] The covering layer 13 may further cover at least a part of the first surface 11a of the main body portion 11. The covering layer 13 may further cover the entire first surface 11a of the main body portion 11.

[0062] As shown in Fig. 4A , the coating layer 13 may cover the entire first surface 11a of the main body portion 11, and the particles 12 may be included in the coating layer 13. However, the form of the coating layer 13 is not limited to the example shown in Fig. 4A . For example, some of the plurality of particles 12 located closer to the first main surface 1a than the main body portion 11 may be included in the coating layer 13. In other words, the plurality of particles 12 located closer to the first main surface 1a than the main body portion 11 may include particles 12 protruding from the coating layer 13.

[0063] Figure 4B is an enlarged view of portion IVB in Figure 4A. In the cross section of the waterproof membrane 1, the height of the particles 12 is defined as height H12, and the thickness of the coating layer 13 in the area where the particles 12 are not present is defined as thickness T13. In this case, the ratio of thickness T13 to height H12 (T13 / H12) is preferably 0.05 to 0.8. When the ratio (T13 / H12) is within the above numerical range, for example, it is easy to achieve an arithmetic mean height Sa of the region R1a of the first principal surface 1a of 0.20 μm or more while suppressing the shedding of the particles 12 from the first surface 11a of the main body 11. In this specification, the height H12 of the particles 12 refers to the vertical distance from the first surface 11a of the main body 11 to the highest point on the surface 12s of the particles 12 in the cross section of the waterproof membrane 1. 4B , when the coating layer 13 covers the surface 12s of the particle 12, the height H12 of the particle 12 means the vertical distance from the first surface 11a of the main body 11 to the highest point on the first principal surface 1a. The thickness T13 of the coating layer 13 in the portion where the particle 12 does not exist means the vertical distance from the first surface 11a of the main body 11 to the highest point on the first principal surface 1a in the cross section of the waterproof membrane 1.

[0064] The lower limit of the ratio (T13 / H12) may be 0.07 or 0.1, and the upper limit of the ratio (T13 / H12) may be 0.7, 0.6, or even 0.5.

[0065] The height H12 of the particles 12 and the thickness T13 of the coating layer 13 can be determined from a cross-sectional SEM image obtained by observing the cross section of the waterproof membrane 1 with an SEM. In the cross-sectional SEM image, the heights of any number of particles 12 (at least 50 particles) are measured. The average value of the measured heights can be considered to be the height H12 of the particles 12. Note that the height of the particles 12 refers to the height in a cross section passing through the center of gravity of the particles 12. Similarly, in the cross-sectional SEM image, the thickness of the coating layer 13 is measured at any locations (at least 50 locations) where no particles 12 are present. The average value of the measured thicknesses can be considered to be the thickness T13 of the coating layer 13.

[0066] The height H12 of the particles 12 is preferably in the range of 0.2 μm to 5 μm. The lower limit of the height H12 of the particles 12 may be 0.3 μm, 0.4 μm, or even 0.5 μm. The upper limit of the height H12 of the particles 12 may be 4.5 μm, 4.0 μm, 3.5 μm, 3.0 μm, 2.5 μm, or even 2.0 μm.

[0067] The thickness T13 of the coating layer 13 in the portion where the particles 12 are not present is preferably in the range of 0.01 μm to 4 μm. The lower limit of the thickness T13 of the coating layer 13 may be 0.014 μm or 0.020 μm. The upper limit of the thickness T13 of the coating layer 13 may be 3.5 μm, 3.0 μm, or even 2.5 μm.

[0068] For example, a resin can be used as a raw material for the coating layer 13. Examples of the resin include a crosslinked silicone oligomer, polyurethane, polyester, polymethyl methacrylate, ethylene vinyl acetate copolymer, and epoxy resin. The coating layer 13 preferably contains a resin as a main component.

[0069] In this embodiment, the main body 11 of the waterproof membrane 1 is a non-porous membrane. Therefore, the waterproof member 10 is particularly suitable for improving waterproofing. In this embodiment, "non-porous" means that there are no pores connecting one main surface of the membrane to the other main surface, or that the number of pores is extremely small. For example, a membrane having an air permeability expressed as a Gurley number of greater than 10,000 seconds / 100 mL can be determined to be a non-porous membrane. Here, the Gurley number is a value obtained by measurement in accordance with JIS P8117:2009.

[0070] There are no particular limitations on the material of the main body 11 of the waterproof membrane 1. Examples of the material of the main body 11 include silicone rubber, polyurethane, polyethylene terephthalate, polyimide, polytetrafluoroethylene, etc. The waterproof membrane 1 may contain, for example, at least one selected from the group consisting of silicone rubber, polyurethane, polyethylene terephthalate, polyimide, and polytetrafluoroethylene.

[0071] The main body 11 of the waterproof membrane 1 may contain an elastomer. The main body 11 may contain an elastomer as a main component. The main body 11 may be made of only an elastomer.

[0072] The elastomer used in the main body 11 of the waterproof membrane 1 is a rubber-like elastic material. The elastomer is preferably a rubber-like elastic material having rubber hardness. The elastomer may be a thermosetting elastomer or a thermoplastic elastomer. The elastomer is not particularly limited. Examples of elastomers include silicone rubber, urethane rubber, ethylene-propylene-diene rubber (EPDM), acrylic rubber, and natural rubber. As the elastomer, one or a combination of two or more selected from these may be used. Among these, silicone rubber and urethane rubber are preferably used. The elastomer may include at least one selected from the group consisting of silicone rubber and urethane rubber.

[0073] The elastomer used in the main body 11 of the waterproof membrane 1 may be silicone rubber.

[0074] The main body 11 of the waterproof membrane 1 may contain urethane rubber. The main body 11 may contain urethane rubber as a main component. The main body 11 may be made of urethane rubber only.

[0075] The main body 11 of the waterproof membrane 1 may contain polytetrafluoroethylene. The main body 11 may contain polytetrafluoroethylene as a main component. The main body 11 may be made of only polytetrafluoroethylene.

[0076] The main body 11 of the waterproof membrane 1 may be colored. If the main body 11 is transparent or white, the waterproof membrane 1 may be noticeable when the waterproof member 10 is placed so as to block an opening in the housing of an apparatus. Therefore, by coloring the main body 11 according to the color of the housing in which it is placed, it is possible to realize a waterproof member 10 that is less noticeable when placed in the housing. The main body 11 may be colored, for example, black. Furthermore, when the design of the housing is important, placing the waterproof member 10 so as to block the opening of the housing may detract from the design. Therefore, by coloring the main body 11 to match the design of the housing, the design can be maintained.

[0077] The coloring of the main body 11 of the waterproof membrane 1 can be achieved, for example, by incorporating a colorant into the raw material of the main body 11. To create a stylish device, it is desirable that the colorant used has the ability to absorb at least a portion of light in the wavelength range of 380 nm or more and 500 nm or less. In other words, it is desirable that the main body 11 be colored black, gray, brown, green, yellow, or pink with this colorant. For example, methods for coloring the main body 11 include mixing a colorant such as a pigment or carbon black into the raw material before it is formed into a sheet, and coloring the raw material after it is formed into a sheet with a colorant using dyeing or printing techniques. Using carbon black as a colorant can improve the strength of the waterproof membrane 1 and also improve its waterproofness.

[0078] The waterproof membrane 1 does not need to contain an organic fluorine compound (PFAS). That is, the waterproof membrane 1 may be a membrane that does not contain an organic fluorine compound.

[0079] 1 and 2, the adhesive layer 2 is annular when viewed from a direction perpendicular to the main surface of the waterproof membrane 1. However, the shape of the adhesive layer 2 is not limited to the example shown in FIGS.

[0080] As used herein, "adhesive" means "sticking" or "adhesion." For example, "adhesive layer" means "adhesive layer" or "adhesive layer."

[0081] As used herein, "pressure-sensitive adhesive," as defined by JIS, refers to a type of adhesion that is temporary and can bond with only slight pressure. It also refers to a property that, while possessing cohesive strength and elasticity, provides strong adhesion, it can also be peeled off from hard, smooth surfaces. Pressure-sensitive adhesives are soft solids and do not undergo state changes like adhesives. Pressure-sensitive adhesives wet to the adherend in their original state and resist peeling, so when adherends are bonded together, they instantly exhibit practical adhesive strength. In other words, pressure-sensitive adhesives possess both the liquid properties (fluidity) that allow them to wet to the adherend and the solid properties (cohesive strength) that resist peeling. Because pressure-sensitive adhesives are soft solids, the contact area with the adherend gradually increases with the application of pressure or over time. Furthermore, because they can maintain this softness for a long period of time, they have the property of being easily removable.

[0082] In this specification, "adhesive" refers to the property of bonding solid surfaces of the same or different types together to form a single unit, as defined by JIS. An adhesive is a fluid substance that wets and blends with the adherends when bonding them together. It then transforms into a solid through heating or chemical reaction, firmly binding the adherends at their interfaces and exerting resistance to peeling. In other words, an adhesive wets the fluid substance and bonds as a solid.

[0083] The material of the adhesive layer 2 can be appropriately selected so that the waterproofing member 10 can be directly attached and fixed to an acoustic component to which it is applied, or so that the adhesive layer 2 can be attached and fixed to a housing that houses the acoustic component. For example, a general-purpose double-sided tape with a substrate, a double-sided tape without a substrate (i.e., a tape with only an adhesive), etc. can be appropriately used as the adhesive layer 2, taking into consideration the adhesiveness to the waterproof membrane 1 and the adhesiveness to a housing or case.

[0084] 1 and 2, the waterproof member 10 is circular when viewed from a direction perpendicular to the main surface of the waterproof membrane 1. However, the shape of the waterproof member 10 is not limited to the example shown in Figures 1 and 2. The shape of the waterproof member 10 may be a circle (including an approximate circle), an ellipse (including an approximate ellipse), or a polygon including a rectangle and a square. The corners of the polygon may be rounded.

[0085] The thickness of the waterproof member 10 is, for example, 2000 μm or less. In this specification, the thickness of the waterproof member 10 refers to the thickness of the waterproof member 10 other than the exposed region 10 a. The thickness of the waterproof member 10 may be 1000 μm or less, 750 μm or less, 600 μm or less, 500 μm or less, 400 μm or less, or even 300 μm or less. The lower limit of the thickness of the waterproof member 10 is, for example, 15 μm.

[0086] In the waterproof member 10, the second main surface 1b of the waterproof membrane 1 may have the same structure as the first main surface 1a. That is, the waterproof membrane 1 may include particles 12 located closer to the second main surface 1b than the main body 11, and the second main surface 1b of the waterproof membrane 1 may have a region having an arithmetic mean height Sa of 0.20 μm or more. The entire second main surface 1b of the waterproof membrane 1 may satisfy the requirement of an arithmetic mean height Sa of 0.20 μm or more. If the second main surface 1b of the waterproof membrane 1 has the same structure as the first main surface 1a, the above-mentioned effects can be obtained regardless of which side of the waterproof membrane 1 faces the opening 51 of the object 50, eliminating the need to be careful about mixing up the main surfaces, and improving handleability.

[0087] [Method for Manufacturing Waterproof Member] The waterproof member 10 described above can be manufactured, for example, by the following method. The manufacturing method will be described below using the waterproof member 10 shown in FIG.

[0088] First, the main body 11 of the waterproof membrane 1 is prepared. The method for preparing the main body 11 is not particularly limited and can be selected appropriately depending on the purpose. For example, a method of extruding the raw material solution of the main body 11 into a thin layer onto a releasable substrate using a discharge means such as a die, or a method of pouring the raw material solution of the main body 11 onto a releasable substrate and then forming a thin film using an applicator, wire bar, or knife coater can be used. Furthermore, the main body 11 may be adjusted to a predetermined thickness by a cutting method. In this way, a sheet-like main body 11 is obtained.

[0089] Next, the particles 12 are arranged on one surface (first surface 11a) of the main body 11. The method for arranging the particles 12 is not particularly limited. For example, a solution containing the particles 12 and the raw materials of the coating layer 13 may be applied to one surface of the main body 11, dried at room temperature, and then heated to arrange the particles 12 on one surface of the waterproof membrane 1. In this manner, a waterproof membrane 1 can be obtained that includes the main body 11 and the particles 12 located closer to the first main surface 1a than the main body 11, and in which the first main surface 1a of the waterproof membrane 1 has a region R1a whose arithmetic mean height Sa is 0.20 μm or more.

[0090] Next, an adhesive sheet (e.g., double-sided tape) is prepared for forming the adhesive layer 2. Holes corresponding to the sound-transmitting regions 4 are formed in the adhesive sheet in advance. This adhesive sheet is attached to the first main surface 1a of the waterproof membrane 1, and then punched into a predetermined shape to obtain the waterproof member 10.

[0091] An example of the waterproofing member according to the first embodiment has been described above using Figures 1 to 6, but the waterproofing member according to the first embodiment is not limited to the above example. Below, another example of the waterproofing member according to this embodiment will be described using Figures 7 to 10. In the modified examples described below, elements common to the waterproofing member 10 described above will be designated by the same reference numerals, and descriptions thereof may be omitted.

[0092] (Modification) Another example of the waterproof member according to the present embodiment is shown in Figures 7 to 10. The waterproof member 20 shown in Figures 7 to 10 further includes a support layer 3 that is arranged apart from the waterproof membrane 1 and has breathability in the thickness direction.

[0093] Fig. 9 is a cross-sectional view showing an example of a state in which the waterproofing member 20 is arranged to block the opening 51 of the object 50. As shown in Fig. 9, when the waterproofing member 20 is arranged to block the opening 51, the support layer 3 is located between the waterproof membrane 1 and the object 50.

[0094] The support layer 3 is attached to limit deformation of the waterproof membrane 1 to a certain range. The support layer 3 has a first main surface 3a facing the opening 51 when the waterproof member 20 is arranged to close the opening 51, and a second main surface 3b facing the first main surface 1a of the waterproof membrane 1. As shown in Fig. 9, when the waterproof member 20 is arranged to close the opening 51, the first main surface 1a of the waterproof membrane 1 and the second main surface 3b of the support layer 3 face each other via a space that contacts the first main surface 1a and the second main surface 3b.

[0095] 10 is a schematic cross-sectional view illustrating the deformation of the waterproof membrane 1 when a water pressure p is applied to the waterproof member 20 in the state shown in FIG. 10. As shown in FIG. 10, when a water pressure p is applied to the waterproof member 20 from the outside of the object 50 (the second main surface 1b side of the waterproof membrane 1) (FIG. 10A), the waterproof membrane 1 deforms so as to be pressed against the second main surface 3b of the support layer 3 (FIG. 10B). In a waterproof member 20 in which the waterproof membrane 1 includes a main body 11 and particles 12 located closer to the first main surface 1a than the main body 11, and the first main surface 1a of the waterproof membrane 1 has a region R1a having an arithmetic mean height Sa of 0.20 μm or more, when the waterproof membrane 1 is deformed so as to be pressed against the second main surface 3b of the support layer 3 by the application of pressure such as water pressure, the contact area between the first main surface 1a of the waterproof membrane 1 and the second main surface 3b of the support layer 3 can be reduced (see FIG. 10B). As a result, after the pressure is released, the first main surface 1 a of the waterproof membrane 1 easily separates from the second main surface 3 b of the support layer 3 and returns to its original shape. In other words, the waterproof membrane 1 is easily restored to its original shape. Therefore, the waterproof member 20 is suitable for suppressing a decrease in sound transmission characteristics.

[0096] 7 and 8, the waterproof member 20 includes a pressure-sensitive adhesive layer 22 bonded to the first main surface 3a of the support layer 3. The pressure-sensitive adhesive layer 22 corresponds to the pressure-sensitive adhesive layer 2 in the waterproof member 10. The pressure-sensitive adhesive layer 22 is disposed on the peripheral edge of the first main surface 3a of the support layer 3. Note that the reference numeral 4 in FIG. 8 indicates a region that transmits sound when the waterproof member 20 is installed in a device, i.e., a sound-transmitting region (sound-passing region).

[0097] 7 and 8 , the waterproof member 20 includes a bonding layer 21 that bonds the first main surface 1a of the waterproof membrane 1 and the second main surface 3b of the support layer 3. The bonding layer 21 is disposed on the peripheral edge of the first main surface 1a of the waterproof membrane 1 and the peripheral edge of the second main surface 3b of the support layer 3.

[0098] 7, the first main surface 1a of the waterproof membrane 1 has an exposed region (exposed region 10a) where the bonding layer 21 is not present. The second main surface 3b of the support layer 3 has an exposed region (exposed region 30a) where the bonding layer 21 is not present.

[0099] 7, the region R1a corresponds to the entire first main surface 1a. That is, the entire first main surface 1a of the waterproof membrane 1 satisfies the requirement that the arithmetic mean height Sa is 0.20 μm or more. With this configuration, the above-described effects of the waterproof member 20 of the embodiment can be more easily achieved.

[0100] However, the position of the region R1a is not limited to the example shown in Figure 7. The region R1a may correspond to the exposed region 10a. That is, the arithmetic mean height Sa in the exposed region 10a may be 0.20 µm or more. Even with such a configuration, the above-described effects of the waterproofing member 20 of this embodiment can be obtained.

[0101] The region R1a may correspond to the overlap region 10b (see FIG. 3). That is, the arithmetic mean height Sa in the overlap region 10b may be 0.20 μm or more. Even with such a configuration, the above-described effects of the waterproofing member 20 of this embodiment can be obtained.

[0102] 7 , the waterproof member 20 has a bonding region J1 where the waterproof membrane 1 and the support layer 3 are bonded, and a non-bonding region J2 surrounded by the bonding region J1 when viewed from a direction perpendicular to the main surface of the waterproof member 20. The bonding region J1 includes the peripheral regions of the waterproof membrane 1 and the support layer 3. The waterproof membrane 1 and the support layer 3 are bonded by a bonding layer 21.

[0103] 7, the waterproof membrane 1 and the support layer 3 are spaced apart from each other in the non-bonding region J2. That is, the support layer 3 is disposed spaced apart from the waterproof membrane 1 in the non-bonding region J2.

[0104] The waterproof member 20 has a difference in insertion loss IL for a sound with a frequency of 1 kHz before and after a water pressure application test in which a water pressure of 0.5 MPa is applied to the second main surface 1b of the waterproof membrane 1 for 10 minutes. D The difference in insertion loss for a sound with a frequency of 1 kHz is IL D is 2.5 dB or less means that the difference in insertion loss IL D does not exceed 2.5 dB.

[0105] In a waterproof member 20 in which the waterproof film 1 includes a main body 11 and particles 12 located closer to the first main surface 1a than the main body 11, and the first main surface 1a of the waterproof film 1 has a region R1a in which the arithmetic mean height Sa is 0.20 μm or more, the difference in insertion loss IL D The difference in insertion loss IL of the waterproofing member 20 is suppressed to 2.5 dB or less. In other words, the deterioration of the sound transmission characteristics is suppressed. D The lower limit of the difference in insertion loss IL D The lower limit is, for example, 0 dB.

[0106] The thickness of the support layer 3 in the non-bonding region J2 is, for example, 500 μm or less. This allows the waterproof member 20 to ensure good sound transmission characteristics while including the support layer 3. The thickness of the support layer 3 may be 300 μm or less, 250 μm or less, 200 μm or less, 150 μm or less, or even 100 μm or less. The lower limit of the thickness of the support layer 3 in the non-bonding region J2 is, for example, 30 μm or 50 μm. The support layer 3 may have the above thickness without being limited to the non-bonding region J2. The entire support layer 3 may have the above thickness.

[0107] The distance between the waterproof membrane 1 and the support layer 3 in the non-bonded region J2 is, for example, 150 μm or less. If the distance is 150 μm or less, it is possible to ensure good sound transmission characteristics even when the support layer 3 is provided. The distance may be 125 μm or less, 100 μm or less, 75 μm or less, or even 50 μm or less. The lower limit of the distance is, for example, 5 μm, and may be 10 μm, 20 μm, or even 30 μm.

[0108] The air resistance in the in-plane direction of the support layer 3 may be 100,000 seconds / 100 mL or more, 150,000 seconds / 100 mL or more, 200,000 seconds / 100 mL or more, 250,000 seconds / 100 mL or more, 300,000 seconds / 100 mL or more, or even exceed 300,000 seconds / 100 mL. The upper limit of the air resistance in the in-plane direction of the support layer 3 is, for example, 1,000,000 seconds / 100 mL or less. The air resistance in the in-plane direction of the support layer 3 can be evaluated as the air resistance between the portion of the non-bonded region J2 on the main surface of the support layer 3 when incorporated into the waterproof member 20 and the outer peripheral side surface 3s of the support layer 3. Here, the air resistance is the time required for 100 mL of air to pass through the member in the in-plane direction.

[0109] 7 and 8, the waterproof member 20 and the non-bonded region J2 are both circular when viewed from a direction perpendicular to the main surface of the waterproof membrane 1. However, the shapes of the waterproof member 20 and the non-bonded region J2 are not limited to the examples shown in Figures 7 and 8. The shapes of the waterproof member 20 and the non-bonded region J2 may be, independently of each other, a circle (including an approximate circle), an ellipse (including an approximate ellipse), or a polygon including a rectangle and a square. The corners of the polygon may be rounded.

[0110] The shape of the bonded region J1 is not limited as long as it surrounds the non-bonded region J2. The bonded region J1 is typically a region including the peripheral edge of the waterproof membrane 1 and / or the support layer 3. In the example shown in FIGS. 7 to 8 , the non-bonded region J2 is the region other than the bonded region J1 where the waterproof membrane 1 and the support layer 3 are bonded. In the example shown in FIGS. 7 to 8 , the waterproof membrane 1 is exposed on one side of the waterproof member 20 (the side facing the outside when placed on the object 50) in the non-bonded region J2. Furthermore, the support layer 3 is exposed on the other side of the waterproof member 20 (the side facing the opening 51 when placed on the object 50) in the non-bonded region J2. In other words, the non-bonded region J2 corresponds to the exposed region 10a and the exposed region 30a.

[0111] The shape of the waterproof membrane 1 and the shape of the support layer 3 may be the same or different when viewed from a direction perpendicular to the main surface of the waterproof membrane 1. In the example shown in Figures 7 and 8, the shape of the waterproof membrane 1 and the shape of the support layer 3 are the same as each other and the same as the shape of the waterproof member 20.

[0112] The thickness of the waterproof member 20 is, for example, 2000 μm or less. In this specification, the thickness of the waterproof member 20 refers to the thickness of the waterproof member 20 in the bonding region J1. The thickness of the waterproof member 20 may be 1000 μm or less, 750 μm or less, 600 μm or less, 500 μm or less, 400 μm or less, or even 300 μm or less. The lower limit of the thickness of the waterproof member 20 is, for example, 50 μm.

[0113] In the waterproof member 20, the second main surface 1b of the waterproof membrane 1 may have the same structure as the first main surface 1a. That is, the waterproof membrane 1 may include particles 12 located closer to the second main surface 1b than the main body 11, and the second main surface 1b of the waterproof membrane 1 may have a region having an arithmetic mean height Sa of 0.20 μm or more. The entire second main surface 1b of the waterproof membrane 1 may satisfy the requirement of an arithmetic mean height Sa of 0.20 μm or more. If the second main surface 1b of the waterproof membrane 1 has the same structure as the first main surface 1a, the above-mentioned effects can be obtained regardless of which side of the waterproof membrane 1 faces the opening 51 of the object 50, eliminating the need to be careful about mixing up the main surfaces, and improving handleability.

[0114] The material constituting the support layer 3 is, for example, metal, resin, or a composite material thereof. The material constituting the support layer 3 is preferably metal because it has excellent strength as the support layer 3. Examples of metal include aluminum and stainless steel. Examples of resin include various resins such as polyolefin (polyethylene, polypropylene, etc.), polyester (polyethylene terephthalate (PET)), polyamide (various aliphatic polyamides and aromatic polyamides including nylon), polycarbonate, and polyimide.

[0115] A specific example of the support layer 3 is a metal plate having one or more through holes connecting the first main surface 3a and the second main surface 3b. A support layer 3 that is a metal plate has particularly excellent strength. Furthermore, when the support layer 3 is a metal plate, the rigidity and handleability of the waterproof member 20 can be improved. The through holes extend, for example, in the thickness direction of the support layer 3. A metal plate having two or more through holes is preferred, as this results in a waterproof member 20 that achieves both sound transmission properties and strength at a higher level. The through holes may be present at least in the portion located in the non-bonding region J2.

[0116] When the support layer 3 has two or more through holes, the openings of each through hole may be regularly arranged or irregularly positioned on the main surface when viewed from a direction perpendicular to the main surface of the metal plate.

[0117] The shape of the opening of the through hole, when viewed from a direction perpendicular to the main surface of the metal plate, is, for example, a circle (including an approximately circle), an ellipse (including an approximately ellipse), and a polygon including a square and a rectangle. The corners of the polygon may be rounded. However, the shape of the opening of the through hole is not limited to the above examples. When there are two or more through holes, the shapes of the openings of the respective through holes may be the same or different.

[0118] An example of a metal plate having two or more through holes is a punched metal, which is a metal plate in which through holes are formed by punching (press-punching).

[0119] The opening ratio of the support layer 3, which is the metal plate, is, for example, 1 to 80%, or may be 1 to 40%, or even 1 to 30%. When the opening ratio is within these ranges, it is possible to obtain a waterproof member 20 that achieves both high levels of sound transmission properties and strength. The opening ratio of the support layer 3, which is the metal plate, is the ratio of the area of ​​the openings of all the through holes present on the main surface to the area of ​​the main surface of the support layer 3.

[0120] Another example of the support layer 3 is a mesh or net made of metal, resin, or a composite material thereof.

[0121] The air permeability in the thickness direction of the support layer 3 is usually higher than that of the waterproof membrane 1. The air permeability in the thickness direction of the support layer 3 is expressed as the air permeability (Fragile air permeability) determined in accordance with the air permeability measurement method A (Fragile method) specified in JIS L1096:2010, and is, for example, 3 / (cm 2 seconds) or more, and 3 / (cm 2 ・Seconds) or more, 300cm 3 / (cm 2 ・seconds) or more, and even 500 cm 3 / (cm 2 The upper limit of the air permeability in the thickness direction of the support layer 3 is, for example, 1000 cm 2 (sec.) as expressed by the Frazier air permeability. 3 / (cm 2 ・seconds) or less.

[0122] Even when the size of the support layer 3 is smaller than the size of the test piece in the Frazier method (approximately 200 mm × 200 mm), the Frazier air permeability can be evaluated by using a measuring jig that limits the area of ​​the measurement area. One example of a measuring jig is a resin plate with a through-hole formed in the center having a cross-sectional area corresponding to the area of ​​the desired measurement area. For example, a measuring jig with a through-hole formed in the center having a circular cross-section with a diameter of 1 mm or less can be used.

[0123] The strength of the support layer 3 is usually higher than the strength of the waterproof membrane 1 .

[0124] 7 and 8, the bonding layer 21 is annular when viewed from a direction perpendicular to the main surface of the waterproof membrane 1. However, the shape of the bonding layer 21 is not limited to the example shown in FIGS.

[0125] 7 and 8, the adhesive layer 22 is annular when viewed from a direction perpendicular to the main surface of the waterproof membrane 1. However, the shape of the adhesive layer 22 is not limited to the examples shown in FIGS.

[0126] As shown in FIGS. 7 and 8, the bonding layer 21 and the adhesive layer 22 may be annular and have the same bonding area.

[0127] The bonding layer 21 is, for example, a pressure-sensitive adhesive layer. However, the configuration of the bonding layer 21 is not limited as long as it is capable of forming the bonding region J1 and the non-bonding region J2. The bonding layer 21, which is a pressure-sensitive adhesive layer, can be formed, for example, by applying a known pressure-sensitive adhesive or adhesive to the peripheral portion of the first main surface 1a of the waterproof membrane 1. The bonding layer 21 may be composed of double-sided adhesive tape. That is, the waterproof membrane 1 and the support layer 3 may be bonded together in the bonding region J1 using double-sided adhesive tape. When the bonding layer 21 is composed of double-sided adhesive tape, the bonding between the waterproof membrane 1 and the support layer 3 is more reliable, further improving the waterproofness of the waterproof member 20. In addition, it is easier to control the distance between the waterproof membrane 1 and the support layer 3 in the non-bonding region J2.

[0128] A known double-sided adhesive tape can be used for the double-sided adhesive tape that constitutes the bonding layer 21. The substrate of the double-sided adhesive tape is, for example, a resin film, nonwoven fabric, or foam. There are no limitations on the resin that can be used for the substrate, and examples include polyester (PET, etc.), polyolefin (polyethylene, etc.), and polyimide. Various adhesives, such as acrylic adhesives and silicone adhesives, can be used for the adhesive layer of the double-sided adhesive tape. It is preferable to use an acrylic adhesive for the adhesive layer, as this can improve the bonding strength between the waterproof membrane 1 and the support layer 3. The double-sided adhesive tape may also be a thermal adhesive tape.

[0129] The thickness of the bonding layer 21 is, for example, 150 μm or less. The upper limit of the thickness of the bonding layer 21 may be 125 μm, 100 μm, 75 μm, or even 50 μm. The lower limit of the thickness of the bonding layer 21 is not particularly limited. The lower limit of the thickness of the bonding layer 21 may be, for example, 5 μm, 10 μm, 20 μm, or even 30 μm.

[0130] As the material for the adhesive layer 22, the materials described for the adhesive layer 2 in the waterproof member 10 can be used.

[0131] The material of the adhesive layer 22 may be the same as the material of the joining layer 21. For example, the same double-sided tape may be used for the adhesive layer 22 and the joining layer 21.

[0132] [Method for Manufacturing Waterproof Member] The waterproof member 20 described above can be manufactured, for example, by the following method. The manufacturing method will be described below using the waterproof member 20 shown in FIG. 7 as an example.

[0133] The manufacturing method described for the waterproof member 10 makes it possible to obtain a waterproof membrane 1 that includes a main body 11 and particles 12 located closer to the first main surface 1a than the main body 11, and in which the first main surface 1a of the waterproof membrane 1 has a region R1a having an arithmetic mean height Sa of 0.20 μm or more.

[0134] Next, a plate-shaped raw material for forming the support layer 3, a first adhesive sheet (e.g., double-sided tape) for forming the bonding layer 21, and a second adhesive sheet (e.g., double-sided tape) for forming the adhesive layer 22 are prepared. Holes corresponding to the sound-transmitting regions 4 are formed in advance in the first and second adhesive sheets. The waterproof membrane 1, the first adhesive sheet, the plate-shaped raw material, and the second adhesive sheet are bonded together in this order so that the second main surface 1b of the waterproof membrane 1 is the outermost surface, and then the waterproof member 20 can be obtained by punching and molding into a predetermined shape.

[0135] The installation method of the waterproofing members 10, 20 is not particularly limited as long as they can protect the acoustic components. For example, the waterproofing members 10, 20 may be directly attached and fixed to the acoustic components to which the waterproofing members 10, 20 are applied using adhesive layers 2, 22. Alternatively, the waterproofing members 10, 20 may be attached and fixed to a housing that houses the acoustic components to which the waterproofing members 10, 20 are applied using adhesive layers 2, 22. In this case, for example, as shown in Figures 3 and 9, the waterproofing members 10, 20 are fixed to the object 50 using adhesive layers 2, 22 so that the waterproof membrane 1 closes an opening 51 provided in the object 50. Note that the opening 51 provided in the object 50 is provided at a position corresponding to the acoustic component for the purpose of allowing sound to pass through.

[0136] In the present embodiment, the waterproof member 10 has been described as having a configuration in which the waterproof membrane 1 is provided with the adhesive layer 2, but the waterproof member 10 does not have to have the adhesive layer 2. In that case, the waterproof member 10 can be installed in a predetermined position by sandwiching and fixing the waterproof membrane 1 with an O-ring or the like, or by fixing with resin sealing. In addition, in the present embodiment, the waterproof member 20 has been described as having a configuration in which the adhesive layer 22 is provided on the support layer 3, but the waterproof member 20 does not have to have the adhesive layer 22. In that case, the waterproof member 20 can be installed in a predetermined position by sandwiching and fixing a laminate composed of the waterproof membrane 1, the bonding layer 21, and the support layer 3 with an O-ring or the like, or by fixing with resin sealing.

[0137] Although not shown in the drawings, the waterproof members 10 and 20 may further have a net or nonwoven fabric or the like provided on the second main surface 1b side of the waterproof membrane 1 for dust prevention.

[0138] Second Embodiment An example of a waterproof member according to the second embodiment is shown in FIG. 11 . The waterproof member 30 shown in FIG. 11 includes a waterproof membrane 1. As shown in FIG. 11 , the waterproof member 30 is disposed inside a microelectromechanical system (MEMS) 60 for use, for example. The MEMS 60 includes a substrate 61 having an opening 611 that functions as a sound vent, a MEMS die 62 having a diaphragm 621, and a cap (cover) 63 that covers the MEMS die 62. The waterproof member 30 is disposed inside the MEMS 60 so as to cover the opening 611 of the substrate 61. The waterproof membrane 1 has a first main surface 1a facing the diaphragm 621 and a second main surface 1b opposite the first main surface 1a. Although not shown, the waterproof membrane 1 includes a main body 11 and particles 12 located closer to the first main surface 1a than the main body 11. The first main surface 1a of the waterproof membrane 1 has a region R1a where the arithmetic mean height Sa is 0.20 μm or more.

[0139] 11 , in the second embodiment, when the waterproof membrane 1 is disposed so as to cover the opening 611 of the substrate 61, the second main surface 1b of the waterproof membrane 1 faces the opening 611. The waterproof membrane 1 provided in the waterproof member 30 of the second embodiment has the same configuration as the waterproof membrane 1 provided in the waterproof member 10 of the first embodiment, except that the second main surface 1b faces the opening 611.

[0140] As shown in Figure 11, when the waterproof member 30 is positioned to block the opening 611, the second main surface 1b of the waterproof membrane 1 and the opening surface 611s face each other via a space that is in contact with the second main surface 1b and the opening surface 611s.

[0141] In a waterproof member 30 in which the waterproof membrane 1 includes a main body 11 and particles 12 located closer to the first main surface 1a than the main body 11, and the first main surface 1a of the waterproof membrane 1 has a region R1a with an arithmetic mean height Sa of 0.20 μm or more, the contact area between the first main surface 1a and the MEMS die 62 can be reduced when the waterproof membrane 1 is deformed by being pressed against the MEMS die 62 due to the application of pressure such as water pressure. As a result, after the pressure is released, the first main surface 1a of the waterproof membrane 1 easily separates from the MEMS die 62 and returns to its original shape. In other words, the deformation of the waterproof membrane 1 is easily recovered. Therefore, the waterproof member 30 of this embodiment is suitable for suppressing deterioration of sound transmission characteristics.

[0142] In the interior 60i of the MEMS 60, the waterproof membrane 1 is disposed with the opening surface 611s of the substrate 61 as the disposition surface, so that the first main surface 1a of the waterproof membrane 1 faces the MEMS die 62. The waterproof membrane 1 is fixed to the MEMS die 62 via a pressure-sensitive adhesive layer 2, and is also fixed to the opening surface 611s of the substrate 61 via an adhesive layer 65. The adhesive layer 65 is located on the opposite side of the waterproof membrane 1 from the pressure-sensitive adhesive layer 2. Furthermore, the adhesive layer 65 overlaps with the pressure-sensitive adhesive layer 2 when viewed from a direction perpendicular to the main surface of the waterproof membrane 1 (in the example of FIG. 11 , the adhesive layer 65 coincides with the pressure-sensitive adhesive layer 2). The MEMS 60 may include any components other than those described above.

[0143] FIG. 11 shows a state in which a MEMS 60 is disposed in an opening 551 in a housing 55 of an electronic device or the like. The MEMS 60 in FIG. 11 is a bottom-port (bottom-opening) microphone element. The MEMS 60 is bonded to the opening 551 in the housing 55. In the example of FIG. 11 , a printed circuit board (PCB) 56 having an opening 561 is bonded to the housing 55, and a substrate 61 of the MEMS 60 and the PCB 56 are connected via a connecting portion 59. The PCB 56 may be a flexible printed circuit (FPC). The connecting portion 59 electrically connects the substrate 61 and the PCB 56 and also fixes the substrate 61 to the PCB 56. For example, solder, conductive resin, or the like can be used as the connecting portion 59.

[0144] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the examples shown below.

[0145] First, the evaluation method for the waterproof member produced in this example will be described.

[0146] The arithmetic mean height Sa of the first main surface of the waterproof membrane and the mean particle size of the particles on the first main surface of the waterproof membrane were evaluated by the above-mentioned method.

[0147] [Configuration of Waterproof Member and Object] The configuration of the waterproof member 70 used in the examples and comparative examples will be described. FIG. 12 is a cross-sectional view showing the configuration of the waterproof member 70 used in the examples and comparative examples. As shown in FIG. 12, the waterproof member 70 included a waterproof membrane 7 and a support layer 9 spaced apart from the waterproof membrane 7 and having breathability in the thickness direction. The waterproof membrane 7 had a first main surface 7a and a second main surface 7b opposite the first main surface 7a. The support layer 9 had a first main surface 9a and a second main surface 9b facing the first main surface 7a of the waterproof membrane 7. The waterproof member 70 included a bonded region j1 ​​where the waterproof membrane 7 and the support layer 9 were bonded by a bonding layer 81, and a non-bonded region j2 surrounded by the bonded region j1 ​​when viewed from a direction perpendicular to the main surface of the waterproof member 70. In the non-bonded region j2, the support layer 9 was spaced apart from the waterproof membrane 7. The support layer 9 was configured to be attachable to the opening surface via a pressure-sensitive adhesive layer 82 bonded to the first main surface 9a. A pressure-sensitive adhesive layer 83 having the same shape as the pressure-sensitive adhesive layer 82 was bonded to the second main surface 7b of the waterproof membrane 7. Note that, since the surface structure of the first main surface 7a of the waterproof membrane 7 varies depending on the examples and comparative examples, the surface structure of the first main surface 7a of the waterproof membrane 7 is not depicted in Fig. 12.

[0148] (Insertion loss IL and insertion loss difference IL D Measurement method) Insertion loss IL and difference in insertion loss IL for sound with a frequency of 1 kHz of the waterproofing material D The measurement method of IL will be described with reference to Fig. 13. The insertion loss IL was measured by the following method using a simulated housing that imitates the housing of a mobile phone shown in Fig. 13.

[0149] As shown in Figures 13A and 13B, a speaker unit 135 to be housed in a simulated housing was fabricated. Specifically, the process is as follows: A speaker 140 (Star Micronics SCC-16A), which serves as a sound source, and fillers 130a, 130b, and 130c made of urethane sponge were prepared. These fillers house the speaker 140 and prevent unnecessary diffusion of sound from the speaker (reducing as much sound as possible that is input to the evaluation microphone without passing through the waterproof material sample being evaluated). A sound-passing opening 132 with a circular cross section and a diameter of 5 mm is provided in the thickness direction of the filler 130a. The filler 130b has a notch shaped to correspond to the shape of the speaker 140 and a notch for housing the speaker cable 142 and leading the speaker cable 142 out of the speaker unit 135. Next, fillers 130c and 130b were placed on top of each other, and speaker 140 and speaker cable 142 were housed in the cutout of filler 130b (FIG. 13A). Next, filler 130a was placed on top of filler 130c so that sound could be transmitted from speaker 140 to the outside of speaker unit 135 through sound passage 132, thereby obtaining speaker unit 135 (FIG. 13B).

[0150] Next, as shown in FIG. 13C , the speaker unit 135 prepared above was housed inside a simulated housing 160 (made of polystyrene, outer dimensions 60 mm × 50 mm × 28 mm) that resembles the housing of a mobile phone. Specifically, the simulated housing 160 prepared consisted of two sections 160a and 160b, which could be fitted together. Section 160a was provided with a sound vent 162 (having a circular cross section with a diameter of 1 mm) that transmits sound emitted from the speaker unit 135 housed therein to the outside of the simulated housing 160, and a conducting hole 164 that leads the speaker cable 142 to the outside of the simulated housing 160. By fitting sections 160a and 160b together, a space with no openings other than the sound vent 162 and the conducting hole 164 was formed inside the simulated housing 160. The manufactured speaker unit 135 was placed on part 160b, and then parts 160a and 160b were fitted together to house the speaker unit 135 inside the simulated housing 160. At this time, the sound vent 132 of the speaker unit 135 and the sound vent 162 of part 160a were overlapped so that sound could be transmitted from the speaker 140 to the outside of the simulated housing 160 through both sound vents 132, 162. The speaker cable 142 was pulled out to the outside of the simulated housing 120 through the conducting hole 164, which was then sealed with putty.

[0151] Next, as shown in FIG. 13D, a sample S of the waterproof member 70 (the area of ​​the non-bonded region j2 is 1.8 mm 2 ) was fixed to the sound vent 162 of the simulated housing 160 by the adhesive layer 83 on the waterproof membrane 7 side. The sample S was fixed so that the entire non-bonded region j2 of the sample S was located within the opening of the sound vent 162 when viewed from a direction perpendicular to the main surface of the waterproof membrane 1.

[0152] 13(E), a microphone 150 (SPU0410LR5H, manufactured by Knowles Acoustics) was fixed to the support layer side of sample S so as to cover the non-bonded region j2 of sample S. The microphone 150 was fixed by a pressure-sensitive adhesive layer 82 on the support layer 9 side of sample S. The distance between the speaker 140 and the microphone 150 when the microphone 150 was fixed varied by up to about 2 mm depending on the thickness of the waterproof member sample to be evaluated, but was in the range of approximately 22 mm to 24 mm. Next, the speaker 140 and microphone 150 were connected to an acoustic evaluation device (B&K Multi-analyzer System 3560-B-030), and the SSR (Solid State Response) mode (test signal 20 Hz to 20 kHz, sweep up) was selected and executed as the evaluation method to evaluate the insertion loss of sample S for a sound with a frequency of 1 kHz. The insertion loss was automatically determined from the test signal input to the speaker 140 from the acoustic evaluation device and the signal received by the microphone 150. When evaluating the insertion loss of sample S, the value of the insertion loss when sample S was removed (blank value) was determined in advance. The blank value was -38 dB at a frequency of 1 kHz. The insertion loss of sample S was the value obtained by subtracting this blank value from the measurement value in the acoustic evaluation device. The smaller the insertion loss value, the better the level (volume) of the sound output from the speaker 140 is maintained.

[0153] A water pressure application test was carried out in which a water pressure p of 0.5 MPa was applied to the second main surface 7b of the waterproof membrane 7 for 10 minutes. The insertion loss IL of the sample S for a sound with a frequency of 1 kHz before and after the water pressure application test was D1 and insertion loss IL D2 The difference (IL D2 -IL D1 ) is the difference in insertion loss IL D It was considered that.

[0154] [Example 1] The waterproof membrane 7 of Example 1 was produced as follows. A thermosetting silicone resin (two-component thermosetting silicone resin, manufactured by Dow Corning Toray Co., Ltd.) was used as the raw material for the main body of the waterproof membrane 7. The thermosetting silicone resin was diluted with ethyl acetate to a solids concentration of 60 wt %, to obtain a coating liquid. The coating liquid was applied to the surface of a release liner (Mitsubishi Plastics, Inc., MRS50), and then dried at 130°C for 3 minutes. After drying, the release liner was removed. This yielded a sheet-like main body. The main body was a non-porous membrane.

[0155] Next, particles were placed on one surface of the main body. The particles used were a composite of silicone rubber particles coated with silicone resin (KPM-600, manufactured by Shin-Etsu Chemical Co., Ltd., average particle size 5 μm). A silicone oligomer crosslinked body (KR-4000G, manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the raw material for the coating layer. A dispersion was obtained by dispersing the particles and the silicone oligomer crosslinked body in an IPA solution so that the particle concentration was 0.7 wt% and the silicone oligomer crosslinked body concentration was 3.7 wt%. The dispersion was applied to one surface of the main body and then air-dried at room temperature (25°C). After drying, the membrane was heated at 160°C for 10 minutes. In this way, the waterproof membrane 7 of Example 1 was obtained. The surface to which the dispersion was applied was designated the first main surface 7a.

[0156] Next, a support layer 9 was attached to the waterproof membrane 7. The support layer 9 was a 100 μm thick punched metal made of SUS304 (opening ratio 15%, Frazier air permeability in the thickness direction 0.26 cm 3 / sec / cm 2The above-mentioned sheet had an in-plane air resistance of more than 300,000 seconds / 100 mmL, and the opening shape of each through-hole was a circle with a diameter of 0.2 mm when viewed perpendicular to the main surface. Double-sided tape (Nitto Denko Corporation, No. 5303W) was used as the first adhesive sheet for forming the bonding layer 81, the second adhesive sheet for forming the adhesive layer 82 on the support layer side, and the third adhesive sheet for forming the adhesive layer 83 on the waterproof membrane side. A circular hole with an inner diameter of 1.6 mm corresponding to the sound-transmitting area was pre-formed in each adhesive sheet. The second adhesive sheet, punched metal, first adhesive sheet, waterproof membrane 7, and third adhesive sheet were bonded together in this order so that the second main surface 7b of the waterproof membrane 7 was the outermost surface, and then punched into a circle with an outer diameter of 5 mm. In this manner, the waterproof member 70 of Example 1 was obtained. In the waterproof member 70 of Example 1, particles were present throughout the entire first main surface 7a of the waterproof membrane 7.

[0157] [Example 2] The waterproof membrane 7 and the waterproof member 70 of Example 2 were produced in the same manner as in Example 1, except that silicone resin particles (KPM-590, manufactured by Shin-Etsu Chemical Co., Ltd., average particle size 2 μm) were used as the particles.

[0158] Fig. 14A shows a diagram (10,000x magnification) illustrating the results of SEM observation of the first main surface 7a of the waterproof membrane 7 of Example 2. Fig. 14B shows a diagram (1,000x magnification) illustrating the results of SEM observation of the first main surface 7a of the waterproof membrane 7 of Example 2.

[0159] [Example 3] The waterproof membrane 7 and the waterproof member 70 of Example 3 were produced in the same manner as in Example 1, except that silica particles (KE-P100, manufactured by Nippon Shokubai Co., Ltd., average particle size 1 μm) were used as the particles.

[0160] Fig. 15A shows a diagram (10,000x magnification) illustrating the results of SEM observation of the first main surface 7a of the waterproof membrane 7 of Example 3. Fig. 15B shows a diagram (1,000x magnification) illustrating the results of SEM observation of the first main surface 7a of the waterproof membrane 7 of Example 3.

[0161] [Example 4] The waterproof membrane 7 and the waterproof member 70 of Example 4 were produced in the same manner as in Example 1, except that silicone resin particles (X-52-854, manufactured by Shin-Etsu Chemical Co., Ltd., average particle size 0.7 μm) were used.

[0162] Fig. 16A shows a diagram (10,000x magnification) illustrating the results of SEM observation of the first main surface 7a of the waterproof membrane 7 of Example 4. Fig. 16B shows a diagram (1,000x magnification) illustrating the results of SEM observation of the first main surface 7a of the waterproof membrane 7 of Example 4.

[0163] [Example 5] The waterproof membrane 7 and the waterproof member 70 of Example 5 were produced in the same manner as in Example 1, except that silica particles (KE-P50, manufactured by Nippon Shokubai Co., Ltd., average particle size 0.5 μm) were used as the particles.

[0164] Fig. 17A shows a diagram (10,000x magnification) illustrating the results of SEM observation of the first main surface 7a of the waterproof membrane 7 of Example 5. Fig. 17B shows a diagram (1,000x magnification) illustrating the results of SEM observation of the first main surface 7a of the waterproof membrane 7 of Example 5.

[0165] [Comparative Example 1] When manufacturing the waterproof membrane 7, particles were not placed on one surface of the main body part. That is, the main body part of Example 1 was used as the waterproof membrane 7 of Comparative Example 1. Except for this, the waterproof membrane 7 and waterproof member 70 of Comparative Example 1 were manufactured in the same manner as in Example 1.

[0166] Comparative Example 2 A dispersion of only the silicone oligomer crosslinked body in an IPA solution was applied to one surface of the main body so that the concentration of the silicone oligomer crosslinked body was 4.3 wt %. In other words, when producing the waterproof membrane 7, only a coating layer was formed on one surface of the main body. Except for this, the waterproof membrane 7 and waterproof member 70 of Comparative Example 2 were produced in the same manner as in Example 1.

[0167] Comparative Example 3 A release embossed PET film having an uneven surface (PG-84 (60° houndstooth dot pattern: embossing height 24 μm, pattern pitch 350 μm) manufactured by Godo Resin Industries Co., Ltd.) was used as the release liner. As a result, the uneven surface was transferred to one surface of the main body when producing the waterproof membrane 7. No particles were placed on one surface of the main body. In other words, the main body having an uneven surface on one surface was used as the waterproof membrane 7 of Comparative Example 1. Except for this, the waterproof membrane 7 and waterproof member 70 of Comparative Example 3 were produced in the same manner as in Example 1.

[0168] Reference Example 1 Silicone resin particles (X-52-854, manufactured by Shin-Etsu Chemical Co., Ltd., average particle size 0.7 μm) were used as the particles. The particles and the crosslinked silicone oligomer were dispersed in an IPA solution so that the particle concentration was 30 wt % and the crosslinked silicone oligomer concentration was 3.7 wt %, to obtain a dispersion. Aside from these, the waterproof membrane 7 of Reference Example 1 was produced in the same manner as in Example 1. However, in Reference Example 1, bonding between the first main surface 7a of the waterproof membrane 7 and the bonding layer 81 could not be ensured, and the waterproof member 70 could not be produced.

[0169] The arithmetic mean height Sa of the first main surface 7a and the mean particle size of the particles on the first main surface 7a were evaluated for the waterproof membranes 7 of Examples 1 to 5, Comparative Examples 1 to 3, and Reference Example 1. The results are shown in Table 1.

[0170] A water pressure application test was carried out on the waterproof members 70 of Examples 1 to 5 and Comparative Examples 1 to 3, and the insertion loss IL D1 and the insertion loss IL after the water pressure application test D2 The difference (IL D2 -IL D1 ) and the difference in insertion loss IL D Furthermore, after the water pressure p in the water pressure application test was released, it was determined by observation using a microscope whether the deformation of the first main surface 7a of the waterproof membrane 7 toward the second main surface 9b of the support layer 9 continued. The results are shown in Table 1.

[0171]

[0172] As shown in Table 1, in the waterproof members 70 of Examples 1 to 5, in which the waterproof membrane 7 contains particles located closer to the first main surface 7a than the main body portion and the first main surface 7a of the waterproof membrane 7 has a region where the arithmetic mean height Sa is 0.20 μm or more, the deformation of the waterproof membrane 7 does not persist after the water pressure p is released, and the deformation of the waterproof membrane 7 is easily recovered, compared to the preventing members 70 of Comparative Examples 1 to 3, which do not satisfy this requirement. The waterproof members 70 of Examples 1 to 5 have a difference in insertion loss IL before and after the water pressure application test. DFrom these results, it was found that a waterproof member 70 in which the waterproof membrane 7 includes particles located closer to the first main surface 7 a than the main body portion and the first main surface 7 a of the waterproof membrane 7 has a region where the arithmetic mean height Sa is 0.20 μm or more is suitable for suppressing a decrease in sound transmission characteristics.

[0173] In the waterproof member 70 of Comparative Example 3, the arithmetic mean height Sa of the first main surface 7a of the waterproof membrane 7 was 0.20 μm or more, but the difference in insertion loss IL D This is presumably because, in the waterproof member 70 of Comparative Example 3, the arithmetic mean height Sa of the first main surface 7 a was obtained by forming an uneven shape by transfer, rather than by the arrangement of particles, and therefore, when the waterproof membrane 7 was deformed by being pressed against the support layer 9 (punched metal), the contact area between the first main surface 7 a of the waterproof membrane 7 and the second main surface 9 b of the support layer 9 was not sufficiently reduced.

[0174] The reason why the waterproof member 70 could not be produced in Reference Example 1 is that the arithmetic mean height Sa of the first main surface 7a of the waterproof film 7 was large, at 1 μm or more, which inhibited bonding between the first main surface 7a and the bonding layer 81. This is thought to be because particles were present over the entire first main surface 7a of the waterproof film 7 in Reference Example 1. Therefore, if the waterproof film 7 of Reference Example 1 is modified so that the particles 12 are present only in the exposed region 10a, it is thought that it can be used without any problems as the waterproof member of the present invention.

[0175] The technology of the present invention can be applied to various electronic devices, such as wearable devices such as smart watches; various cameras; communication devices such as mobile phones and smartphones; and sensor devices.

Claims

1. A waterproof member that is placed to close an opening of an object having an opening surface with an opening formed therein, the waterproof member comprising a waterproof membrane having a first main surface facing the opening when placed to close the opening and a second main surface opposite the first main surface, the waterproof membrane including a main body and particles located closer to the first main surface than the main body, and the first main surface of the waterproof membrane having a region with an arithmetic mean height of 0.20 μm or more.

2. The waterproof member according to claim 1, wherein the object comprises a microelectromechanical system (MEMS).

3. The waterproof member according to claim 1, wherein the average particle size of the particles in the region of the first main surface is in the range of 0.2 μm to 5 μm.

4. The waterproof member according to claim 1, wherein the waterproof membrane further includes a coating layer covering at least a portion of the surface of the particles.

5. The waterproof member according to claim 1, wherein the arithmetic mean height of the region of the first main surface is less than 1 μm.

6. A waterproof member as described in claim 1, in which the difference in insertion loss for sound with a frequency of 1 kHz before and after a water pressure application test in which a water pressure of 0.5 MPa is applied to the second main surface of the waterproof membrane for 10 minutes is 2.5 dB or less.

7. The waterproof member according to claim 1, wherein the main body of the waterproof membrane is a non-porous membrane.

8. The waterproof member according to claim 1, wherein the main body of the waterproof membrane comprises at least one material selected from the group consisting of silicone rubber, polyurethane, polyethylene terephthalate, polyimide, and polytetrafluoroethylene.

9. The waterproof member according to claim 1, wherein the main body of the waterproof membrane comprises an elastomer.

10. A waterproof member as described in claim 1, wherein when the waterproof member is positioned to block the opening, the first main surface of the waterproof membrane and the opening surface face each other via a space adjacent to the first main surface and the opening surface.

11. The waterproof member according to claim 1, further comprising an adhesive layer bonded to the first main surface of the waterproof membrane.

12. A waterproof member as described in claim 1, further comprising a support layer that is spaced apart from the waterproof membrane and has breathability in the thickness direction, the support layer being positioned between the waterproof membrane and the object when the waterproof member is positioned to block the opening.

13. A waterproof member as described in claim 12, wherein the support layer has a first main surface facing the opening and a second main surface opposite the first main surface when the waterproof member is positioned to block the opening, and the waterproof member further comprises: a bonding layer bonding the first main surface of the waterproof membrane to the second main surface of the support layer; and a pressure-sensitive adhesive layer bonded to the first main surface of the support layer.

14. A waterproof member arranged to close an opening inside a microelectromechanical system (MEMS) having a substrate with an opening that functions as a sound vent, a MEMS die with a vibration plate, and a cap that covers the MEMS die, the waterproof member comprising: a waterproof membrane having a first main surface facing the vibration plate and a second main surface opposite the first main surface when arranged to close the opening; the waterproof membrane including a main body and particles located closer to the first main surface than the main body; and the first main surface of the waterproof membrane having a region with an arithmetic mean height of 0.20 μm or more.

15. A waterproofing member that is placed so as to close an opening of an object having an opening surface on which an opening is formed, comprising a waterproofing membrane having a first main surface and a second main surface opposite to the first main surface, the waterproofing membrane including a main body and particles located closer to the first main surface than the main body, the first main surface of the waterproofing membrane having a region having an arithmetic mean height of 0.20 μm or more, and when placed so as to close the opening, the first main surface or the second main surface of the waterproofing membrane faces the opening.

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