Composite film, composite film preparation method and microphone

Abstract

The invention discloses a composite film, a composite film preparation method and a microphone. The composite membrane comprises a fiber membrane layer, the fiber membrane layer is provided with a plurality of pores, the pores are filled with silicone rubber filler, and / or at least one surface of the fiber membrane layer in the thickness direction is covered with a silicone rubber layer. The fiber membrane layer can provide high mechanical strength for the composite membrane, and the silicone rubber filler filled in the gaps and / or the silicone rubber layer covering the surface of the fiber membrane layer can improve the waterproof performance of the composite membrane, so that the overall strength and waterproof performance of the composite membrane can be improved.

Description

Technical Field

[0001] This invention relates to the field of acoustic-to-electric conversion technology, and more specifically, to a composite membrane, a method for preparing the composite membrane, and a microphone. Background Technology

[0002] In related technologies, a waterproof membrane is typically installed at the microphone's sound port to improve its waterproof performance. However, current waterproof membranes have poor performance and are insufficient to meet waterproof requirements in environments with high water pressure.

[0003] Therefore, a new technical solution is needed to solve the above-mentioned technical problems. Summary of the Invention

[0004] One object of the present invention is to provide a new technical solution for composite membranes.

[0005] According to a first aspect of the present invention, a composite membrane is provided. The composite membrane comprises: A fiber membrane layer having a plurality of pores filled with a silicone rubber filler, and / or, at least one surface of the fiber membrane layer along its thickness direction is covered with a silicone rubber layer.

[0006] Optionally, the fiber membrane layer includes at least one of polyimide fiber membrane, polyethersulfone fiber membrane, polyetherimide fiber membrane, polybenzimidazole fiber membrane, polyaryletherketone fiber membrane, or polyamideimide fiber membrane.

[0007] Optionally, the outer surface of the fiber membrane is covered with a silicone rubber layer.

[0008] Optionally, the thickness of the fiber membrane is 3 μm to 20 μm.

[0009] Optionally, the thickness of the silicone rubber layer is 3μm to 30μm.

[0010] Optionally, the pore size of the fiber membrane is 0.2 μm to 2 μm.

[0011] According to a second aspect of the present invention, a method for preparing a composite membrane as described in the above embodiments is provided, the method comprising: The raw materials are dissolved in a solvent to prepare a solution; The solution is stretched into nanofibers under the action of an electric field and deposited on the substrate to form a fiber membrane. Silicone rubber slurry is applied to the surface of the fiber membrane layer; The silicone rubber slurry is cured.

[0012] Optionally, the concentration of the solution is 8 wt% to 12 wt%.

[0013] Optionally, the step of coating the surface of the fiber membrane with silicone rubber slurry includes: The silicone rubber slurry is uniformly coated onto the surface of the fiber membrane using a scraper, with the distance between the scraper and the fiber membrane being 3μm to 30μm.

[0014] Optionally, the fiber membrane layer moves relative to the scraper at a speed of 1 m / min to 5 m / min.

[0015] Optionally, stretching the solution into nanofibers under an electric field and depositing them on a substrate to form a fiber membrane includes: The voltage that forms the electric field is 15kV to 25kV; The solution is sprayed toward the substrate through a spinneret, with the distance between the spinneret and the substrate being 10cm to 20cm, and the spraying speed of the solution being 0.1ml / h to 0.5ml / h.

[0016] According to a third aspect of the present invention, a microphone is provided, the microphone comprising the composite diaphragm described in the above embodiments.

[0017] One technical advantage of this application is that the composite membrane includes a fiber membrane layer having multiple pores filled with silicone rubber filler, and / or, at least one surface of the fiber membrane layer along the thickness direction is covered with a silicone rubber layer. The fiber membrane layer can provide the composite membrane with high mechanical strength, while the silicone rubber filler filling the pores and / or the silicone rubber layer covering the surface of the fiber membrane layer can improve the waterproof performance of the composite membrane, thereby improving the overall strength and waterproof performance of the composite membrane.

[0018] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0020] Figure 1 This is a cross-sectional schematic diagram of a composite membrane according to an embodiment of this application.

[0021] Figure 2 This is a schematic diagram of the structure of a composite membrane according to an embodiment of this application.

[0022] Figure 3 This is a schematic flowchart of a composite membrane preparation method according to an embodiment of this application.

[0023] Figure 4 This is a schematic diagram of the structure of a microphone according to an embodiment of this application.

[0024] Figure 5 This is a schematic diagram of the structure of a microphone according to another embodiment of this application.

[0025] Figure label: 1. Composite membrane; 11. Fiber membrane layer; 12. Silicone rubber filler; 13. Silicone rubber layer; 2. Microphone; 21. Housing; 22. Substrate; 221. Sound hole; 222. Mounting groove; 23. MEMS chip; 24. ASIC chip; 25. Gold wire; 26. Inner cavity; 27. Protective component; 271. Through hole. Detailed Implementation

[0026] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0027] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0028] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0029] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0030] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0031] According to one embodiment of this application, a composite membrane 1 is provided. For example... Figure 1 and Figure 2 As shown, the composite membrane 1 includes a fiber membrane layer 11 having a plurality of pores filled with silicone rubber filler 12, and / or, at least one surface of the fiber membrane layer 11 along the thickness direction is covered with a silicone rubber layer 13.

[0032] In this example, the fiber membrane layer 11 can provide high mechanical strength to the composite membrane 1, while the silicone rubber filler 12 filling the gaps and / or the silicone rubber layer 13 covering the surface of the fiber membrane layer 11 can improve the waterproof performance of the composite membrane 1, thereby improving the overall strength and waterproof performance of the composite membrane 1.

[0033] like Figure 1 and Figure 2 As shown, in this example, the fiber membrane layer 11 can serve as the skeleton of the composite membrane 1, possessing strong mechanical strength, thereby improving the strength of the composite membrane 1. The fiber membrane has a porous structure; therefore, the fiber membrane layer 11 has multiple pores. Silicone rubber filler 12 is filled into the pores of the fiber membrane layer 11. Because silicone rubber has good elasticity and low air permeability, it possesses excellent waterproof performance. Therefore, by filling the pores of the fiber membrane layer 11 with silicone rubber filler 12, the composite membrane 1 can possess both strong mechanical strength and good waterproof performance.

[0034] In this example, a silicone rubber layer 13 can also be applied to the surface of the fiber membrane layer 11 along its thickness direction, which can give the composite membrane 1 both strong mechanical strength and good waterproof performance. For example, the silicone rubber layer 13 can be applied to one surface of the fiber membrane layer 11 along its thickness direction, or both surfaces can be covered with the silicone rubber layer 13. The fiber membrane layer 11 has a side surface between the two surfaces along its thickness direction, and the silicone rubber layer 13 can also be applied to the side surface, which further improves the waterproof performance of the composite membrane 1.

[0035] In this example, a silicone rubber layer 13 is applied to the surface of the fiber membrane layer 11, and silicone rubber filler 12 is filled into the pores of the fiber membrane layer 11, thereby further improving the waterproof performance of the composite membrane 1. For example, the composite membrane 1 of this application exhibits good waterproof performance in water at depths of 10m to 50m.

[0036] It should be noted that the fiber membrane layer 11 can be prepared by electrospinning. Liquid silicone rubber slurry can be uniformly coated on the surface of the fiber membrane layer 11 through a casting process. Since the fiber membrane layer 11 has multiple pores, the liquid silicone rubber slurry has strong fluidity, allowing it to flow into and fill the pores of the fiber membrane layer 11. After the liquid silicone rubber slurry cures, a silicone rubber layer 13 can be formed on the surface of the fiber membrane layer 11, and silicone rubber filler 12 can be filled into the pores of the fiber membrane layer 11.

[0037] In one example, the fiber membrane layer 11 includes at least one of a polyimide fiber membrane, a polyethersulfone fiber membrane, a polyetherimide fiber membrane, a polybenzimidazole fiber membrane, a polyaryletherketone fiber membrane, or a polyamide-imide fiber membrane.

[0038] In this example, the fiber membrane prepared from polyimide, polyethersulfone, polyetherimide, polybenzimidazole, polyaryletherketone, or polyamideimide possesses strong mechanical strength and high-temperature resistance to adapt to different application scenarios of the composite membrane 1. The fiber membrane layer 11 is prepared by electrospinning from one of the following materials: polyimide, polyethersulfone, polyetherimide, polybenzimidazole, polyaryletherketone, or polyamideimide. Alternatively, the fiber membrane layer 11 can be prepared by mixing multiple materials and then electrospinning.

[0039] Of course, the fiber membrane 11 can also be made of other materials, which can be determined by those skilled in the art according to the actual situation, and no specific limitation is made here.

[0040] In this example, the silicone rubber includes polydimethylsiloxane or polymethylsiloxane, along with added catalysts or fillers. Those skilled in the art can determine the appropriate components based on the specific circumstances, and no specific limitations are made here.

[0041] like Figure 1 As shown, in one example, the outer surface of the fiber membrane layer 11 is covered with a silicone rubber layer 13. The fiber membrane layer 11 includes two first surfaces along its thickness direction and a second surface located between the two first surfaces. The two ends of the second surface are respectively connected to the two first surfaces. The silicone rubber layer 13 is covered on both the first and second surfaces, which helps to further improve the waterproof performance of the composite membrane 1.

[0042] In one example, the thickness of the fiber membrane 11 is 3 μm to 20 μm.

[0043] In this example, if the thickness of the fiber membrane layer 11 is less than 3 μm, the overall mechanical strength of the composite membrane 1 will be insufficient. Conversely, if the thickness of the fiber membrane layer 11 is greater than 20 μm, the overall volume of the composite membrane 1 will be large, which is not conducive to the miniaturization design of the composite membrane 1. Therefore, setting the thickness of the fiber membrane layer 11 to 3 μm to 20 μm ensures that the composite membrane 1 has good mechanical strength while also facilitating its miniaturization design.

[0044] For example, the thickness of the fiber membrane layer 11 can be 3μm, 5μm, 8μm, 10μm, 15μm or 20μm, etc., which can be determined by those skilled in the art according to the actual situation, and no specific limitation is made here.

[0045] In one example, the thickness of the silicone rubber layer 13 is 3 μm to 30 μm.

[0046] In this example, if the thickness of the silicone rubber layer 13 is less than 3 μm, the waterproof performance of the composite membrane 1 will be poor. If the thickness of the silicone rubber layer 13 is greater than 30 μm, the overall volume of the composite membrane 1 will be large, which is not conducive to the miniaturization design of the composite membrane 1. Therefore, setting the thickness of the fiber membrane layer 11 to 3 μm to 30 μm can ensure that the composite membrane 1 has good waterproof performance while also facilitating the miniaturization design of the composite membrane 1.

[0047] For example, the thickness of the silicone rubber layer 13 can be 3μm, 5μm, 8μm, 10μm, 15μm, 20μm or 25μm, etc., which can be determined by those skilled in the art according to the actual situation, and no specific limitation is made here.

[0048] In one example, the pore size of the fiber membrane 11 is 0.2 μm to 2 μm.

[0049] In this example, if the pore size of the fiber membrane layer 11 is less than 0.2 μm, the overall density of the composite membrane 1 will be relatively high, its elasticity will be low, and the silicone rubber slurry will not easily penetrate into the pores of the fiber membrane layer 11. Conversely, if the pore size of the fiber membrane layer 11 is greater than 2 μm, the excessively large pore size will easily lead to insufficient mechanical strength. Therefore, setting the pore size of the fiber membrane layer 11 to 0.2 μm to 2 μm ensures that the composite membrane 1 has both good elasticity and good mechanical strength.

[0050] For example, the pore size of the pores in the fiber membrane layer 11 can be set to 0.2μm, 0.5μm, 0.8μm, 1.0μm, 1.5μm or 2μm, etc., which can be determined by those skilled in the art according to the actual situation, and no specific limitation is made here.

[0051] According to another aspect of this application, a method for preparing the composite membrane 1 in the above embodiments is provided. For example... Figure 3 As shown, the preparation method includes: S100. Dissolve the raw material in a solvent to obtain a solution. The raw material can be a polyimide precursor, which typically has good solubility and processability. Dissolve the polyimide precursor in a solvent to obtain a solution.

[0052] In this example, the raw material is dissolved in a solvent to obtain a solution concentration of 8 wt% to 12 wt%. When preparing fiber membranes via electrospinning, if the solution concentration is too low, continuous fibers cannot be formed; if the solution concentration is too high, it is difficult to spin or results in beaded fibers. For example, the solution concentration can be 8 wt%, 9 wt%, 10 wt%, 11 wt%, or 12 wt%, etc., which can be determined by those skilled in the art according to the actual situation, and no specific limitation is made here.

[0053] S200. The solution is stretched into nanofibers under the action of an electric field and deposited on a base film to form a fiber membrane layer 11. That is, through the electrospinning process, the solution is stretched into nanofibers under the action of a high voltage electric field, and the nanofibers are deposited on the base film, thereby forming a fiber membrane on the base film, which is the fiber membrane layer 11 of the composite membrane 1.

[0054] In this example, the solution is sprayed towards the substrate film through a spinneret. The sprayed jet can be stretched and refined (its diameter can be reduced to tens to hundreds of nanometers) in an electric field, while the solvent evaporates. The voltage forming the electric field is 15kV to 25kV. The voltage affects the magnitude of the electrostatic force; too high a voltage may lead to jet instability, while too low a voltage will prevent jet formation. For example, the voltage can be 15kV, 18kV, 20kV, 23kV, or 25kV, etc., which can be determined by those skilled in the art based on the actual situation, and is not specifically limited here.

[0055] In this example, the solution is sprayed towards the base film through a spinneret. The distance between the spinneret and the base film is 10cm to 20cm, which is the receiving distance in the electrospinning process. If the receiving distance is less than 10cm, the jet flight time is insufficient, and the solvent does not have enough time to evaporate. If the receiving distance is greater than 20cm, the jet may be overstretched, easily leading to fiber breakage and other problems. In this application, the distance between the spinneret and the base film is 10cm to 20cm, allowing the jet sufficient flight time so that the solvent can evaporate as much as possible, thus forming dry fibers with stable structure and uniform diameter. For example, the distance between the spinneret and the base film can be set to 10cm, 12cm, 15cm, 18cm, or 20cm, etc., which can be determined by those skilled in the art according to the actual situation, and is not specifically limited here.

[0056] In this example, the spinneret ejects the solution at a rate of 0.1 ml / h to 0.5 ml / h to facilitate the formation of a dry fiber membrane with a uniform diameter. For example, the ejection rate of the solution from the spinneret can be 0.1 ml / h, 0.2 ml / h, 0.3 ml / h, 0.4 ml / h, or 0.5 ml / h, etc., which can be determined by those skilled in the art according to the actual situation, and is not specifically limited here.

[0057] In this example, after forming a polyimide electrospun fiber membrane on the base film, the electrospun fiber membrane is dried to remove residual solvent, thereby obtaining a dried polyimide fiber membrane.

[0058] S300. Apply silicone rubber slurry to the surface of the fiber membrane layer 11. A silicone rubber layer 13 can be formed on the surface of the fiber membrane layer 11 through a casting process. Different types of silicone rubber are selected according to application requirements; different silicone rubbers have different properties, such as temperature resistance, transparency, and hardness. The silicone rubber slurry is uniformly applied to the surface of the fiber membrane layer 11 using a doctor blade. The liquid silicone rubber slurry has strong fluidity and flows into the pores of the fiber membrane, thereby filling the pores. The surface of the fiber membrane layer 11 is also uniformly coated with silicone rubber slurry.

[0059] In this example, the distance between the scraper and the fiber membrane layer 11 is 3μm to 30μm. That is, the scraper gap is 3μm to 30μm, so that a silicone rubber layer 13 of a predetermined thickness can be formed on the surface of the fiber membrane layer 11. For example, the distance between the scraper and the fiber membrane layer 11 can be 3μm, 5μm, 10μm, 15μm, 20μm, 25μm, or 30μm, etc., which can be determined by those skilled in the art according to the actual situation, and is not specifically limited here.

[0060] In this example, the fiber film layer 11 is moved at a uniform speed by a driving device. The moving speed of the fiber film layer 11 relative to the doctor blade is 1 m / min to 5 m / min, that is, the casting speed is 1 m / min to 5 m / min. This ensures both casting efficiency and allows the silicone rubber slurry to fully fill the pores of the fiber film layer 11. For example, the casting speed can be 1 m / min, 2 m / min, 3 m / min, 4 m / min, or 5 m / min, etc., which can be determined by those skilled in the art according to the actual situation, and is not specifically limited here.

[0061] S400. Curing the silicone rubber slurry. After uniformly coating the silicone rubber slurry onto the fiber membrane layer 11, the composite membrane 1 is heat-cured at 80℃-120℃ for 2h-4h to cure the silicone rubber slurry.

[0062] According to another aspect of this application, a microphone 2 is provided. (As...) Figure 4 and Figure 5 As shown, the microphone 2 includes the composite membrane 1 described in the above embodiment. The microphone 2 has a sound hole 221, and the composite membrane 1 can be sealed at the sound hole 221 of the microphone 2, thereby providing a waterproof function.

[0063] like Figure 4 and Figure 5As shown, in this example, the microphone 2 includes a housing 21 and a substrate 22. The substrate 22 can be sealed and welded to the opening of the housing 21, and the housing 21 and the substrate 22 surround each other to form an inner cavity 26. The housing 21 can be a metal shell, and the substrate 22 can be a circuit board. The microphone 2 also includes a MEMS chip 23 and an ASIC chip 24, which are mounted on the substrate 22 and located within the inner cavity 26. The MEMS chip 23 and the ASIC chip 24 are electrically connected by gold wires 25. A sound hole 221 is provided through the substrate 22 along its thickness direction, connecting the inner cavity 26 to the outside. The MEMS chip 23 has a diaphragm, and the position of the diaphragm corresponds to that of the sound hole 221.

[0064] like Figure 4 As shown, in this example, the composite diaphragm 1 can be sealed at the sound hole 221 of the microphone 2, and the composite diaphragm 1 can be located in the inner cavity 26. The composite diaphragm 1 can serve as a waterproof membrane for the microphone 2, improving its waterproof performance. After receiving an external sound signal, the composite diaphragm 1 can vibrate, thereby driving the diaphragm on the MEMS chip 23 to vibrate, achieving a sound pickup effect. A protective member 27 is also mounted on the substrate 22, and the protective member 27 has a through hole 271 along its thickness direction. The composite diaphragm 1 can be bonded to the substrate 22, and the protective member 27 can cover the composite diaphragm 1 to protect it. The MEMS chip 23 is mounted on the side of the protective member 27 away from the composite diaphragm 1, and the position of the diaphragm corresponds to the through hole 271 to improve the sensitivity of the diaphragm's sound pickup.

[0065] like Figure 5 As shown, in this example, the composite membrane 1 can be located outside the inner cavity 26. That is, the substrate 22 is provided with a mounting groove 222 on the side away from the inner cavity 26. The composite membrane 1 can be installed in the mounting groove 222 and seal the sound hole 221 to improve the waterproof performance of the microphone 2.

[0066] Example 1: Polyimide electrospun fiber membrane is used as the fiber membrane layer 11 of composite membrane 1. The pore size of the fiber membrane layer 11 is about 0.5μm-2μm and the thickness of the fiber membrane layer 11 is 4μm.

[0067] Silicone rubber slurry: Select soft silicone rubber with low modulus and high flexibility, and add a small amount of bubble stabilizer.

[0068] Casting process: A doctor blade casting method is used, with a doctor blade gap of 5μm and a casting speed of 2m / min.

[0069] Silicone rubber slurry curing: heat curing at 80°C for 2 hours.

[0070] Test results: Under a water pressure test of 100 kPa, the sound loss of microphone 2 was less than 3 dB. This demonstrates that the protective membrane of this application effectively prevents water from entering the sound hole 221, thus improving the waterproof performance of microphone 2.

[0071] Case 2: Polyimide electrospun fiber membrane is used as the fiber membrane layer 11 of composite membrane 1. The pore size of the fiber membrane layer 11 is about 0.2μm-0.8μm and the thickness of the fiber membrane layer 11 is 4μm.

[0072] Silicone rubber slurry: Select soft silicone rubber with low modulus and high flexibility, and add a small amount of bubble stabilizer.

[0073] Casting process: A doctor blade casting method is used, with a doctor blade gap of 8μm and a casting speed of 2m / min.

[0074] Silicone rubber slurry curing: heat curing at 100℃ for 3 hours.

[0075] Test results: When the water pressure test reaches 500 kPa, the sound loss of microphone 2 is less than 5 dB. This demonstrates that the protective membrane of this application can effectively prevent water from entering the sound hole 221, thus improving the waterproof performance of microphone 2.

[0076] The above embodiments mainly describe the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be elaborated here.

[0077] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A composite film, characterized by, The composite membrane comprises: a fibrous membrane layer (11) having a plurality of pores, the pores being filled with a silicone rubber filler (12), and / or at least one surface of the fibrous membrane layer (11) in the thickness direction being covered with a silicone rubber layer (13).

2. The composite film according to claim 1, characterized by, The fibrous membrane layer (11) comprises at least one of a polyimide fibrous membrane, a polyether sulfone fibrous membrane, a polyetherimide fibrous membrane, a polybenzimidazole fibrous membrane, a polyaryletherketone fibrous membrane, or a polyamide-imide fibrous membrane.

3. The composite film of claim 1, wherein, An outer surface of the fibrous membrane layer (11) is covered with a silicone rubber layer (13).

4. The composite film of claim 1, wherein The fibrous membrane layer (11) has a thickness of 3 μm to 20 μm.

5. The composite film of claim 1, wherein The silicone rubber layer (13) has a thickness of 3 μm to 30 μm.

6. The composite film of claim 1, wherein The pores of the fibrous membrane layer (11) have a pore size of 0.2 μm to 2 μm.

7. A method for producing the composite film according to any one of claims 1 to 6, characterized by, The composite membrane comprises: dissolving raw materials in a solvent to obtain a solution; stretching the solution into nanofibers under the action of an electric field and depositing the nanofibers on a base membrane to form a fibrous membrane layer; applying a silicone rubber paste to a surface of the fibrous membrane layer; curing the silicone rubber paste.

8. The method of claim 7, wherein the method further comprises, The concentration of the solution is 8 wt% to 12 wt%.

9. The method of claim 7, wherein the composite film is prepared by a method comprising: The application of the silicone rubber paste to the surface of the fibrous membrane layer comprises: uniformly applying the silicone rubber paste to the surface of the fibrous membrane layer (11) by a doctor blade, the distance between the doctor blade and the fibrous membrane layer (11) being 3 μm to 30 μm.

10. The method of claim 9, wherein the composite film is prepared by a method comprising: The fibrous membrane layer (11) moves relative to the doctor blade at a speed of 1 m / min to 5 m / min.

11. The method of claim 7, wherein the composite film is prepared by a method comprising: The stretching of the solution into nanofibers under the action of an electric field and the depositing of the nanofibers on a base membrane to form a fibrous membrane layer comprises: the voltage for forming the electric field being 15 kV to 25 kV; the solution being sprayed toward the base membrane by a spinneret, the distance between the spinneret and the base membrane being 10 cm to 20 cm, and the spraying speed of the solution being 0.1 ml / h to 0.5 ml / h.

12. A microphone, comprising: The composite membrane comprises any one of claims 1 to 6.

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