CN110271119B

CN110271119B - Method for manufacturing waterproof breathable film by using mold

Info

Publication number: CN110271119B
Application number: CN201910434872.1A
Authority: CN
Inventors: 周宇轩
Original assignee: Shenzhen Yisheng Acoustics Technology Co ltd
Current assignee: Shenzhen Yisheng Acoustics Technology Co ltd
Priority date: 2019-05-23
Filing date: 2019-05-23
Publication date: 2021-07-20
Anticipated expiration: 2039-05-23
Also published as: CN110271119A

Abstract

The invention provides a method for manufacturing a waterproof breathable film by utilizing a mold, wherein the mold comprises a substrate and a plurality of mutually spaced columns fixed on the first surface of the substrate, and the cross section of each column is in a micron-scale size. The method comprises the following steps: performing injection molding, and injecting a filling material into the mold, so that the filling material fills a gap surrounded by the substrate and the plurality of columns; demolding, and separating the injection molded filling material from the mold, wherein all or part of the columns are separated from the substrate and remain in the molded filling material, so as to obtain a membrane; and removing the residual column in the membrane to obtain the waterproof and breathable membrane. The waterproof breathable film obtained in the invention can not only ensure the ventilation and sound transmission quality, but also have enough film thickness, thereby ensuring the strength of the waterproof breathable film and improving the waterproof depth of the waterproof breathable film.

Description

Method for manufacturing waterproof breathable film by using mold

[ technical field ] A method for producing a semiconductor device

The invention belongs to the acoustic field of microphones, loudspeakers, buzzers and the like, and particularly relates to a method for manufacturing a waterproof breathable film by using a mold.

[ background of the invention ]

Many devices such as existing smart phones, tablet computers and watches capable of communicating have waterproof requirements. In order to achieve better waterproof effect, the best method is to make the equipment into a fully closed state. With the wide application of wireless charging and wireless earphones, the number of holes in devices such as smart phones, tablet computers and watches capable of communicating is less and less, and only a microphone hole for sound pressure input and a loudspeaker hole for sound pressure output are left in the left holes. This is because the path of sound propagation cannot be completely closed for better sound transmission. How to ensure that the path of sound transmission which is not completely closed can be effectively waterproof is a problem to be solved.

The current technology is to use a waterproof breathable film for waterproof sealing. The existing waterproof breathable films generally used are all organic materials, a plurality of micron-scale small holes are formed in the films, sound can smoothly pass through the small holes, and water cannot pass through the small holes due to tension, so that the waterproof function on a sound transmission path is realized. However, for process reasons, the film must be made thin by making the pores small enough. The organic material is soft and easy to damage, and can be damaged when being touched by hands in the installation process, and special protection needs to be designed in practical application. Secondly, there is an upper limit to the water pressure that can be tolerated, i.e. the depth to which the membrane is waterproofed, due to insufficient strength of the membrane.

The existing technology is to stick a layer of waterproof breathable film on a metal sheet, the metal sheet is provided with big holes, and the metal structure between the holes is used as a reinforcing rib to strengthen the pressure resistance of the organic film. However, the organic film has limited compressive capacity, and even if the organic film is reinforced by a metal structure, the organic film is difficult to meet the increasingly high waterproof requirement proposed by more and more new products.

Therefore, there is a need for an improved solution to overcome the above problems.

[ summary of the invention ]

The invention aims to provide a method for manufacturing a waterproof breathable film by utilizing a mold, and the manufactured waterproof breathable film can ensure the ventilation and sound transmission quality and also has enough film thickness, so that the strength of the waterproof breathable film can be ensured.

According to one aspect of the present invention, there is provided a method for manufacturing a waterproof, breathable film using a mold comprising a substrate and a plurality of pillars fixed to a first surface of the substrate, the pillars being spaced apart from each other, the pillars having a cross-sectional size of the order of micrometers, the method comprising: performing injection molding, and injecting a filling material into the mold, so that the filling material fills a gap surrounded by the substrate and the plurality of columns; demolding, and separating the injection molded filling material from the mold, wherein all or part of the columns are separated from the substrate and remain in the molded filling material, so as to obtain a membrane; and removing the residual column in the membrane to obtain the waterproof and breathable membrane.

Compared with the prior art, the waterproof breathable film is prepared by adopting a disposable die through a die casting method. Therefore, the waterproof breathable film can not only ensure the ventilation and sound transmission quality, but also have enough film thickness, thereby ensuring the strength of the waterproof breathable film and improving the waterproof depth of the waterproof breathable film.

[ description of the drawings ]

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise. Wherein:

FIG. 1 is a schematic view of a partial longitudinal cross section of a film directly after perforation;

FIG. 2 is a schematic longitudinal sectional view of a diaphragm perforated by an anisotropic etching process;

FIG. 3 is a schematic structural view of a mold for manufacturing a waterproof breathable film according to an embodiment of the present invention;

FIG. 4 is a schematic longitudinal sectional view of the mold for manufacturing the waterproof breathable film shown in FIG. 3 after film injection;

FIG. 5 is a schematic longitudinal sectional view of the waterproof breathable film obtained after the demolding of FIG. 4;

FIG. 6 is a schematic structural view of a mold for manufacturing a waterproof breathable film according to another embodiment of the present invention;

FIG. 7 is a schematic structural view of a mold for manufacturing a waterproof, breathable film according to yet another embodiment of the present invention;

FIG. 8 is a schematic structural view of the mold of FIG. 7 after demolding to obtain a membrane;

FIG. 9 is a schematic view of the diaphragm pressurization process of FIG. 8;

FIG. 10 is a schematic flow chart of a molding method using the mold of FIG. 7;

FIG. 11 is a top view of different shapes of double-sided offset holes in a waterproof breathable film;

FIG. 12 is a schematic view of a single-sided molded waterproof, breathable membrane of a double-layered cylinder mold of the present invention in another embodiment;

FIG. 13 is a schematic view of a double-sided molded waterproof, breathable membrane of a double-layer column mold and a single-layer column mold according to another embodiment of the invention;

FIG. 14 illustrates a first method of making a mold for a two-layer cylinder in accordance with an embodiment of the present invention;

FIG. 15 is a second method of making a mold for a two-layer cylinder according to one embodiment of the present invention;

FIG. 16 illustrates a third method of making a mold for a two-layer cylinder in accordance with an embodiment of the present invention;

FIG. 17 is a schematic illustration of an additive down-hole process;

FIG. 18 is a schematic view of a pressurized blown-liquid material necking process;

fig. 19 is a schematic view of a process for processing a disposable mold using a photolithography process.

[ detailed description ] embodiments

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

Reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic may be included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Unless otherwise specified, the terms connected, and connected as used herein mean electrically connected, directly or indirectly.

The shape of the "hole" referred to in the present invention may be various cross-sectional shapes such as a circle, a square, a rectangle, etc., and the hole diameter refers to the maximum width or the minimum width of the cross-section of the hole, but not necessarily to the diameter of the circular hole, for example, the cross-section of the hole is a square, so the hole diameter of the hole may refer to the length of the diagonal line or one side of the square, and the term diameter in the hole diameter does not mean that the cross-section of the hole is necessarily a circle, and the diameter in this case is a broad concept and may refer to the maximum width or the minimum width of the cross-section of the hole, for example, the diameter of the rectangular hole may refer to the length of the diagonal line or the short side of the rectangular hole.

In waterproof ventilated membrane, the effective through-hole area per unit area means: the diameter of each through-hole may vary on the membrane (or membrane sheet), the area at the smallest diameter of each through-hole being the hole effective through-hole area, and the sum of the hole effective through-hole areas of all the through-holes on the membrane per unit area being the unit area effective through-hole area (hereinafter simply referred to as effective area). Obviously, to increase the effective via area per unit area, on one hand, the variation of the aperture of the holes is small as much as possible, and on the other hand, the density of the holes is increased.

One of the major manufacturing difficulties of the waterproof breathable film is that, on one hand, the diameter of the pores on the film needs to be as small as possible in order to improve the waterproof property of the film, and on the other hand, the film needs to have a certain thickness in order to ensure the strength of the film. The ratio of the depth to the diameter (abbreviated as depth-to-diameter ratio) of the through hole in the film is high, which causes difficulty in processing. The manufacturing process may be selected according to the requirements of the application.

The first method is to directly perforate (or perforate a single surface) the prepared film sheet 110 to form a plurality of micron-sized through holes 120, as shown in fig. 1, which is a partial longitudinal sectional view of the film sheet after it is directly perforated. The punching process includes mechanical processing, electric spark processing, laser processing, 3D (3Dimensions, three-dimensional) printing, chemical etching, ion etching, photolithography, and the like. The minimum aperture is about 10 microns, the aperture is large, the water pressure which can be borne by the membrane is not too high, the perforating is difficult if the depth-diameter ratio is high, the mechanical strength requirement of the membrane by mechanical processing is high, and holes cannot be made too densely. Due to the limitation of the size of a light spot, the minimum aperture which can be generally made by laser processing is about 10 microns, the perforating is difficult if the depth-diameter ratio is higher, the processing effect by using ultrafast laser (nanosecond, picosecond and femtosecond laser) is better, but the processing cost of a large number of holes one by one is higher. The problem of high depth-diameter ratio is easy to solve because of additive manufacturing, but the minimum precision of the conventional 3D printing is 10 microns, which means that it is difficult to manufacture deep holes with the diameter of less than 10 microns. By using a chemical etching method, it is possible to manufacture a hole with a small aperture, but the size of the hole is related to the depth of the through hole, the isotropic etching is difficult to manufacture the through hole with a high depth-diameter ratio, and the aperture change is large. In the case of anisotropic etching, there is almost no material with an etching angle close to a right angle in the existing material, which means that the through hole can only be a taper with a certain angle, and only can satisfy the application with low requirement on effective area, as shown in fig. 2, which is a schematic longitudinal cross section of the diaphragm after being punched by the anisotropic etching process, wherein the taper angle of the through hole 220 formed on the diaphragm 210 is fixed. The sizes of the holes of the ion etching and the direct photoetching can be well controlled, but the processing is difficult if the depth-to-diameter ratio is higher, the processing cost is higher, and the performance of the photoetching photoresist serving as a structural material cannot meet the requirement of higher requirement if the photoresist is directly photoetched, and a subsequent reverse mold process is generally combined.

In order to overcome the above-mentioned disadvantages of direct perforation of the film sheet, the present invention provides a second method for producing a waterproof breathable film. The second method is to manufacture the diaphragm by a reverse mould process, and the manufacture of the mould is the key.

Single-sided die casting process

Fig. 3 is a schematic structural view of a mold for manufacturing a waterproof breathable film according to an embodiment of the present invention. The mold for manufacturing a waterproof and breathable film shown in fig. 3 includes a substrate 310 and a plurality of pillars 320, the pillars 320 are fixed on the first surface 312 of the substrate 310, and the pillars 320 are spaced and densely arranged, a cross-sectional dimension (or width) of the pillars 320 is in a micron order, for example, a cross-sectional width of the pillars 320 may be less than or equal to 50 microns, preferably less than or equal to 20 microns, and an aspect ratio of the pillars 320 may be between 1 and 15, preferably between 3 and 15, such as 8 or 10.

The column 320 may be a cylinder, a rectangular prism, a square prism, a triangular prism, etc.

The mold for manufacturing the waterproof breathable film shown in fig. 3 can be classified into a mold that can be used many times and a mold that is disposable. The mold for multiple use is required to have high strength and is generally made of metal. The processing method can be mechanical processing, electric spark processing, laser processing, 3D printing, chemical etching and/or ion etching and the like. In order to provide a relatively high aspect ratio for the holes in the film (or membrane) after the reverse molding, the pillars 320 need to have a relatively high aspect ratio, for example, the aspect ratio may be between 1 and 15, preferably, between 3 and 15, such as 8 or 10, which is relatively fragile and requires relatively high processing. The manufacturing process may be selected according to the requirements of the application.

The following describes a molding process using the mold for manufacturing a waterproof breathable film shown in fig. 3, with reference to fig. 4 and 5.

First, injection molding is performed. Fig. 3 shows a filling material 410 injected into the mold for manufacturing the waterproof breathable film, so that the filling material 410 fills the gap surrounded by the substrate 310 and the plurality of pillars 320, specifically as shown in fig. 4, fig. 4 is a schematic longitudinal cross-sectional view of the mold for manufacturing the waterproof breathable film shown in fig. 3 after film injection. The casting method of the step of film injection can be casting, injection molding, electroforming and the like; the filler material 410 may be a metal, a non-metal, an organic, or a composite of multiple materials.

Then, the mold is released. The injection molded filling material 410 is released from the mold for manufacturing the waterproof breathable film shown in fig. 3 to obtain the waterproof breathable film, as shown in fig. 5. Fig. 5 is a schematic longitudinal sectional view of the waterproof breathable film obtained by demolding the waterproof breathable film shown in fig. 4, wherein the waterproof breathable film shown in fig. 5 comprises a film sheet 510 and a plurality of through holes 520 penetrating through the film sheet 510, the through holes 520 penetrate from a first surface 512 of the film sheet 510 to a second surface 514 of the film sheet 510, and the through holes 520 are arranged at intervals. The aperture of the through hole 520 is in micron order, the depth-diameter ratio thereof may be between 1 and 15, preferably between 3 and 15, such as 8 or 10, and the aperture of the through hole may be less than or equal to 50 microns, preferably less than or equal to 20 microns.

In this embodiment, the present invention employs a single-side molding process to manufacture the waterproof breathable film, so as to overcome the processing difficulties caused by the high aspect ratio of the holes. Therefore, the waterproof breathable film prepared by the invention has higher effective through hole area per unit area to ensure the ventilation and sound transmission quality, and the film thickness is enough to ensure the strength of the film, thereby improving the waterproof depth.

When the mold of the present invention is used, the cylinder 320 is easily damaged during demolding due to its fragile structure (especially when the aspect ratio is high). An improvement is to taper the cylinder. The taper angle formed by anisotropic etching is material dependent and cannot be controlled. It is generally desirable that the taper angle be programmable. One way of processing is to process the mold at a designed angle and taper the cylinder either by changing the mold to a fixed angle or by changing the processing angle with a processing tool. Machining, electric spark machining, laser machining and ion etching can all achieve the same point under the micro-size.

Fig. 6 is a schematic structural diagram of a mold for manufacturing a waterproof breathable film according to another embodiment of the present invention. As shown in fig. 6, the mold includes a substrate 610 and a plurality of pillars 620, and the pillars 620 are fixed on a first surface of the substrate 610. The cylinder 620 is a taper with a thick root and a thin end, and the taper here can be a taper in a broad sense, including a frustum, a cone, a pyramid, and the like. Thus, the mold is not easily damaged at the time of demolding.

Double-sided die casting process

In addition to the single-sided molding shown in fig. 3-5, a double-sided molding may be used to manufacture the waterproof, breathable membrane.

Fig. 7 is a schematic structural view of a mold for manufacturing a waterproof and breathable film according to still another embodiment of the present invention. As shown in fig. 7, the mold includes a first mold unit 710 and a second mold unit 720. Each mold unit includes a base plate 730 and a plurality of cylinders 740. The pillars 740 are fixed on the first surface of the substrate 710, the pillars 740 are spaced and densely arranged, and the cross-sectional dimension of the pillars 740 is micron-sized. The first mold unit 710 and the second mold unit 720 are placed opposite to each other with the first surface of the substrate of the first mold unit 710 facing and parallel to the first surface of the substrate of the second mold unit 720, one or more of the plurality of columns 740 of the first mold unit 710 being disposed opposite to one or more of the plurality of columns 740 of the second mold unit 720, and the ends of the opposite columns of the first mold unit 710 and the second mold unit 720 being spaced apart from each other.

In one application, the aspect ratio of the pillars 740 of the first mold unit 710 and the aspect ratio of the pillars 740 of the second mold unit 720 may be between 1 and 15, preferably between 3 and 15, such as 8 or 10, and the cross-sectional width of the pillars may be less than or equal to 50 microns, preferably less than or equal to 20 microns. Due to the double-sided molding, the height-to-width ratio of the posts 740 of each mold unit 710 may be smaller, which may be easier to manufacture and stronger. The detailed description of each mold unit can also refer to the above single-side molding mold, which is not described herein.

Fig. 10 is a flow chart illustrating a molding method 900 using the mold of fig. 7. The molding method 900 is described with reference to fig. 7-9, fig. 8 is a schematic view of a structure of a film sheet obtained after demolding of the mold in fig. 7, and fig. 9 is a schematic view of a film sheet pressurization process in fig. 8. The molding method 900 includes the following steps.

Step 910, as shown in fig. 7, the first mold unit 710 and the second mold unit 720 are placed opposite to each other, with the first surface of the substrate 730 of the first mold unit 710 facing and parallel to the first surface of the substrate 730 of the second mold unit 720, and the plurality of pillars 740 of the first mold unit 710 are respectively opposite to the plurality of pillars 740 of the second mold unit 720, and a filling material 805 is injected between the first mold unit 710 and the second mold unit 720, so that the filling material fills the gap between the substrates.

And 920, demolding as shown in fig. 8, and separating the filling material subjected to injection molding from the mold of the waterproof breathable film to obtain the film 810. The diaphragm 810 has a first surface 811 and a second surface 812 opposite the first surface. A plurality of first layer holes 813 are formed extending from the first surface 811 of the diaphragm 810, and a plurality of second layer holes 814 are formed extending from the second surface 812 of the diaphragm 810. Each second layer hole 814 is opposite to at least one first layer hole 813.

Step 930, as shown in fig. 9, pressurizing one side of the membrane 810 to make the holes on the two sides of the membrane 810 penetrate, so as to obtain the waterproof breathable membrane. At this time, the second layer hole 814 communicates with the first layer hole 813 opposite thereto to form a through hole penetrating the waterproof breathable film 810. The pressure may be air pressure or other fluid pressure.

It can be seen that the waterproof vented membrane comprises a membrane sheet 810, a plurality of first layer apertures 813 extending into the membrane sheet from a first surface of the membrane sheet 810, and a plurality of second layer apertures 814 extending into the membrane sheet from a second surface of the membrane sheet 810.

In fig. 7-9, a second layer of holes 814 is offset from and communicates with an opposing first layer of holes 813, and the cross-sectional area of the intersection of the second layer of holes 814 and the opposing first layer of holes 813 is smaller than the cross-sectional area of the second layer of holes 814 and the first layer of holes 813, thereby reducing the effective aperture of the via. In one application, the first layer of pores and the second layer of pores may have a pore size of 50 microns or less, preferably 20 microns or less, and may have a depth to diameter ratio of 1 to 15, preferably 3 to 15, such as 8 or 10. Of course, in other embodiments, one second layer of apertures may be opposed to a plurality of first layer of apertures by providing respective first and second mould units.

In the above embodiment, the ends of the columns 740 of the first mold unit 710 and the second mold unit 720 are spaced apart from each other and do not contact each other, so that the holes on both sides of the waterproof and breathable film 810 are not penetrated after the mold is removed, and thus it is necessary to penetrate the film under pressure. In another modified embodiment, the ends of the columns 740 of the first mold unit 710 and the second mold unit 720 can be designed to contact with each other, so that the holes on both sides of the waterproof and breathable film 810 are directly through after demolding, and the step of pressing through can be omitted.

Therefore, in the embodiment, the waterproof breathable film is manufactured by adopting a double-sided die casting process, so that the processing difficulty can be further reduced. Fig. 3-6 and the related descriptions in the single-sided molding process described above, such as the manufacturing method of the mold unit, the casting method of the injection molding step, the material of the filling material, the shape of the cylinder, etc., can be introduced into the double-sided molding process, and the description will not be repeated here for clarity.

Fig. 11 is a top view of a different shape of a double-sided offset hole (or through hole) manufactured by the die casting method shown in fig. 10 according to the present invention. As shown in fig. 11(a), a circular upper-layer hole (which may be referred to as a first-layer hole) is formed on the upper surface (which may be referred to as a first surface) side of the diaphragm, and a circular lower-layer hole (which may be referred to as a second-layer hole) is formed on the lower surface (which may be referred to as a second surface) side of the diaphragm, and the circular upper-layer hole and the circular lower-layer hole are alternately communicated. As shown in fig. 11(b), a square upper hole is formed on the upper surface side of the diaphragm, a square lower hole is formed on the lower surface side of the diaphragm, and the square upper hole and the square lower hole are communicated with each other in a staggered manner. As shown in fig. 11(c), a square upper hole is formed on the upper surface side of the diaphragm, a circular lower hole is formed on the lower surface side of the diaphragm, and the square upper hole and the circular lower hole are communicated with each other in a staggered manner. As shown in fig. 11(d), 4 square upper holes are formed on the upper surface side of the diaphragm, and one corresponding circular lower hole is formed on the lower surface side of the diaphragm, and the 4 square upper holes are in staggered communication with the 1 circular lower hole.

Mould of multilayer cylinder

In the above embodiments, the cylinders in the mold are all single-layered.

In another embodiment, the cylinder of the mold may also be made in a multi-layer structure. Fig. 12 is a schematic view of a single-sided die cast waterproof, breathable membrane of a double-layered cylinder mold of the present invention in another embodiment. Referring to fig. 12, the mold includes a substrate 1210 and a plurality of posts 1220, only one of which is schematically shown in fig. 12, and the other posts are not shown. The pillars 1220 are fixed on the first surface of the substrate 1210, the pillars 1220 are spaced and densely arranged, and the cross-sectional dimension (or width) of the pillars 1220 is micron-sized. Each of the pillars 1220 includes a first pillar portion 1221 formed to extend from a first surface of the substrate 1210 and one or more second pillar portions 1222 formed to extend from ends of the first pillar portion 1221, wherein a cross-sectional width of the first pillar portion 1221 is greater than a cross-sectional width of the second pillar portion. The aspect ratio of the first column portion and the second column portion may be between 1 and 15, preferably between 3 and 15, such as 8 or 10, and the width of the cross section of the second column portion 1222 may be less than or equal to 50 microns, preferably less than or equal to 20 microns. The second body 1222 may be single or plural.

The waterproof breathable film 1205 can be molded using a mold having a double-layer cylinder as shown in fig. 12, and the molding method can be described with reference to the above-mentioned single-sided molding, which is not repeated here. The waterproof vented membrane 1205 comprises a membrane, a plurality of first layer holes extending into the membrane from a first surface of the membrane, and a plurality of second layer holes extending into the membrane from a second surface of the membrane. Each first layer hole corresponds to the first column portion 1221, and each second layer hole corresponds to the second body portion 1222, such that each first layer hole corresponds to and communicates with a plurality of first layer holes, and the second layer holes have cross-sections with widths smaller than the cross-sections of the first layer holes. The depth-diameter ratio of the first layer hole and the second layer hole can be between 1 and 15, preferably between 3 and 15, and the width of the cross section of the first layer hole can be less than or equal to 50 micrometers, preferably less than or equal to 20 micrometers.

Fig. 13 is a schematic view of a double-sided molded waterproof, breathable membrane of a double-layer column mold and a single-layer column mold according to another embodiment of the invention. In another embodiment, as shown in FIG. 13, waterproof, breathable membrane 1305 may also be fabricated by double-sided molding using a mold having a double-layer cylinder comprising base 1310 and a plurality of cylinders 1320, wherein the cylinders 1320 are single-layer cylinders, in conjunction with a single-layer cylinder mold as shown in FIG. 3. In another embodiment, the single-layer cylinder mold of FIG. 13 can be replaced with a double-layer cylinder mold.

For the mold with double-layer columns, the width of the section of the first column part 1221 is larger, so that the ratio can be made higher, and the width of the cross section of the second main body part 1222 is smaller, so that the effective aperture of the through hole in the waterproof breathable film 1205 can be reduced. The plurality of second column parts 122 are arranged, so that the effective through hole area per unit area of the waterproof and breathable film can be increased.

Fig. 14 illustrates a first method of manufacturing a mold for a double-layered cylinder according to an embodiment of the present invention. As shown in fig. 14, the manufacturing method includes the following steps.

In the first step, a substrate may be prepared;

in the second step, a large first column 1221 is machined on one surface of the substrate by machining, electrical discharge machining, laser machining, 3D printing, chemical etching, ion etching, photolithography, or the like.

In a third step, a small second post portion 1222 is machined on the end of the large first post portion. The second column portion 1222 of each first column portion 1221 may be one or more. The small second column portion is relatively fine in size, and is typically fabricated by processes suitable for processing fine dimensions, such as chemical etching, ion etching, photolithography, and the like. The height of the small column body is not well controlled by the method, and the method is generally realized by strictly controlling the processing conditions and the processing time and has higher requirement.

In this embodiment, the base 1210, the first column 1221, and the second column 1222 of the mold are all made of the same material.

Fig. 15 illustrates a second method of manufacturing a mold for a double-layered cylinder according to an embodiment of the present invention. As shown in fig. 15, the manufacturing method includes the following steps.

In the first step, two layers of substrates, i.e., substrate 1 and substrate 2, may be prepared, where substrate 1 may also be referred to as a first substrate or a lower substrate, and substrate 2 may also be referred to as a second substrate or an upper substrate. The upper substrate may be formed by spraying, coating, spinning a liquid substrate onto the lower substrate and then curing, or may be attached to the lower substrate by additive methods such as electroplating, electroforming, 3D printing, chemical deposition, vapor deposition, and the like. The thickness of the upper substrate can be controlled accurately and uniformly.

In the second step, a large first column 1221 is formed on the upper surface of the second substrate by machining, electrical discharge machining, laser machining, 3D printing, chemical etching, ion etching, or photolithography.

In a third step, a small second column portion 1222 is processed on the end of the large first column portion 1221, and the size of the small second column portion is relatively fine, generally by a processing method suitable for processing fine size, such as chemical etching, ion etching, photolithography, etc. The second column portion 1222 of each first column portion 1221 may be one or more.

As can be seen, the first post 1221 is formed of a first substrate, the second post 1222 is formed of a second substrate, and the substrate 1210 is formed of a first substrate. Because the upper and lower materials of the base material are different, the material properties can be utilized to be different in chemical etching, ion etching or photoetching, and only the upper base material is processed without influencing the lower base material in processing.

Fig. 16 illustrates a third method of manufacturing a mold for a double-layered cylinder according to an embodiment of the present invention. As shown in fig. 16, the manufacturing method includes the following steps.

A first step of preparing a substrate 1 (also referred to as a first substrate or a lower substrate);

in the second step, a large first column 1221 is first machined on one surface of the substrate 1, and the machining method may be machining, electrical discharge machining, laser machining, 3D printing, chemical etching, ion etching, photolithography, or the like.

In the third step, the large first column 1221 is immersed in a liquid base material, the liquid level is controlled by a method such as self-leveling or rotation of the liquid, and the liquid base material is solidified to obtain a base material 2 (also referred to as a first base material, a lower base material).

In the fourth step, the second column portion 1222 is processed on the substrate 2 above the first column portion 1221 by a processing method, chemical etching, ion etching, photolithography, or the like. The second column portion 1222 of each first column portion 1221 may be one or more. In fig. 16 only a small part of the upper layer of the substrate 2 is involved in the precision machining, and in practice the substrate 2 may also be subdivided into two layers, the upper layer being of a material involved in the precision machining and the lower layer being replaced by another cheaper material which can be easily removed after machining.

Further, in one embodiment, the waterproof breathable film of the invention further comprises a support frame (not shown) formed with large holes (or through holes), the membrane formed with the through holes can be attached to the support frame, and the structure between the large holes is used as a reinforcing rib to enhance the pressure resistance of the membrane. Wherein, the support frame is a metal sheet or a high-strength high polymer material. If the compressive strength of the waterproof breathable film is high enough, the waterproof performance is better, and the film can be directly used if the film strength is high, the supporting requirement of a metal bracket (or a supporting frame) is not needed or reduced, and the installation and the operation are more convenient.

Furthermore, the novel waterproof breathable film manufactured by adopting the reverse mold process is firmer, durable, not easy to damage and capable of bearing higher water pressure than the traditional waterproof breathable film, so that the waterproof breathable film can be used in microphones and loudspeakers. Because the loudspeaker sound production vibration plate is a film, the loudspeaker sound production vibration plate and the waterproof breathable film can be integrated on one film, and the device cost is reduced. In one embodiment, the micro-speaker comprises a housing, a motor assembly located in the housing, and a vibrating plate connected to the inner side wall of the housing, wherein the vibrating plate and the waterproof and breathable membrane are integrated on one membrane.

Treatment of shrinkage cavities

After the through holes are formed in the diaphragm, the effective aperture can be further reduced by adopting a hole shrinkage process to perform hole shrinkage treatment so as to make up for the defects that the processing process is limited and the hole size is difficult to be reduced. The through-holes may be formed in the membrane in the manner described above or in other manners known in the art.

Figure 17 illustrates an additive crater process. Additive 1730 can be slowly accumulated on the surface of the membrane 1710 by using methods such as electroplating, electroforming, chemical deposition, vapor deposition, etc., and tends to close the through hole 1720, and the purpose of reducing the size of the through hole on the surface of the membrane can be achieved by controlling the accumulation speed and the accumulation time of the additive.

FIG. 18 is a schematic view of a pressurized liquid material necking process. As shown in fig. 18, a rotating liquid or semi-liquid substrate 1830 is sprayed, coated, etc. onto the surface of the membrane 1810, the liquid tension tending to close the through-holes 1820. Applying air pressure or other fluid pressure to one side of the membrane 1810 blows the layer of the liquid substrate 1830 open, and the liquid substrate is cured by properly controlling the fluid pressure, thereby reducing the size of the through hole.

Disposable mould

When the mold shown in fig. 3, 6, 7, 12-16 is used, the column structure is fragile (especially when the aspect ratio is high), and the mold is easily damaged during demolding. The disposable mould can be considered, the cylinder structure is deliberately destroyed during demoulding, the cylinder structure is remained on the membrane, and then the cylinder structure is removed through other processes, so that the waterproof and breathable membrane is obtained.

The strength requirement of the disposable mould on the mould material is greatly reduced, and the mould can be made of metal, nonmetal, organic matter or composite material. The machining mode can be mechanical machining, electric spark machining, laser machining, 3D printing, chemical etching, ion etching, photoetching and the like. The advantages and disadvantages of the machining method are similar to those of the mold which is used for multiple times, and the manufacturing process can be selected according to the requirements of the application.

For example, the mold shown in fig. 15 may be a disposable mold, and the

pillar structures

1221, 1222 may be intentionally peeled off of the substrate 1210 of the mold with the film during demolding, after which the pillars in the film may be removed in other ways.

Because the mould is disposable, the processing cost is greatly improved. Photolithography is a process that is well suited to the requirements of most applications.

Firstly, coating photoresist on a substrate;

secondly, carrying out exposure photoetching on the photoresist by using a mask plate; after illumination, the material properties are changed and can be distinguished from other materials;

and finally, forming the photoresist into a cylinder of the mold through a developing technology, wherein the substrate is the substrate of the mold.

The sizes of the columns and the gaps can be controlled to be smaller in the photoetching process. The processing of the gap between the high aspect ratio column and the high aspect ratio is difficult. The processing cost is relatively low, and the method is suitable for batch production.

In the case of the mold shown in FIG. 19, when the waterproof breathable film is produced, the film is left in the through holes of the film sheet due to all or part of the columns after the film is removed from the mold. The residual pillars can be removed by using the difference between the material properties of the membrane and the pillars. The removing method comprises corrosion, temperature-controlled liquefaction or vaporization, reaction with other gases or liquids under certain temperature and pressure conditions to form gas or liquid, dissolution by other liquids or gases and the like.

Similar to the multi-use mold, the disposable mold can also be made into a cone shape, which is beneficial to making the column body high (as shown in figure 6) and can be obtained by a double-sided casting mold and a staggered casting mold, and the through hole film has thicker strength and larger effective area.

Single-side die casting and punching process

In another embodiment, a single-side molding process may be performed by using a mold as shown in fig. 3-6 and 12 to obtain a membrane with holes on one surface, unlike the embodiment shown in fig. 3-6 and 12, in this embodiment, the holes on the membrane are only located on one surface of the membrane and do not penetrate through the membrane, and these holes may be referred to as first layer holes. Then, a punching process may be used to punch holes on the other surface of the membrane to form second layer holes, and the first layer holes and the corresponding second layer holes are communicated to form through holes. Wherein each second layer of apertures may correspond to one or more first layer of apertures. The drilling process may include machining, electrical discharge machining, laser machining, 3D (3 dimensional) printing, chemical etching, ion etching, photolithography, and the like.

The shape and arrangement of the first layer of holes and the punched holes and the second layer of holes formed by single-sided molding may be as shown in fig. 11 and will not be repeated here.

It should be noted that those skilled in the art can make modifications to the embodiments of the present invention without departing from the scope of the appended claims. Accordingly, the scope of the appended claims is not to be limited to the specific embodiments described above.

Claims

1. A method of manufacturing a waterproof, breathable membrane using a mold comprising a substrate and a plurality of pillars spaced apart from each other and fixed to a first surface of the substrate, the pillars having a cross-sectional dimension in the order of micrometers, the method comprising:

performing injection molding, and injecting a filling material into the mold, so that the filling material fills a gap surrounded by the substrate and the plurality of columns;

demolding, and separating the injection molded filling material from the mold, wherein all or part of the columns are separated from the substrate and remain in the molded filling material, so as to obtain a membrane;

and removing the residual column in the membrane to obtain the waterproof and breathable membrane.

2. The method of claim 1,

the injection molding method is casting, injection molding or electroforming,

the filling material is metal, nonmetal, organic matter or is compounded by multiple materials,

the method for removing the residual cylinder in the membrane comprises corrosion, temperature-controlled liquefaction or vaporization.

3. The method of claim 1, wherein the holes on both sides of the membrane have not been through-drilled after removing the remaining pillars in the membrane, the method further comprising:

and pressurizing one side of the obtained membrane to ensure that the holes on the two sides of the membrane are communicated, so as to obtain the waterproof breathable membrane.

4. The method of claim 1, further comprising:

and (3) carrying out shrinkage processing on the waterproof breathable film by adopting an additive process or a pressurized liquid material blowing process.

5. The method of claim 1,

the pillars are formed photolithographically from a photoresist,

the mould is made of metal, nonmetal, organic matter or composite material.

6. The method of claim 1,

each pillar includes a first pillar portion formed extending from the first surface of the substrate and one or more second pillar portions formed extending from ends of the first pillar portion, wherein a cross-sectional width of the first pillar portion is greater than a cross-sectional width of the second pillar portion.

7. The method of claim 6, wherein the ratio of the height to the cross-sectional width of each of the first and second column portions is between 1 and 15, the cross-sectional width of the second column portion is less than or equal to 50 microns,

the plurality of pillars are densely arranged on the substrate.

8. The method of claim 6, wherein the substrate, the first cylindrical portion and the second cylindrical portion are made of the same material, and the mold is machined by machining, electrical discharge machining, laser machining, 3D printing, chemical etching or/and ion etching; alternatively, the first and second electrodes may be,

the first column part is formed by first base materials, the second column part is formed by second base materials, the substrate is formed by the first base materials, the first column part is formed by machining, electric spark machining, laser machining, 3D printing, chemical etching, ion etching or photoetching, and the second column part is formed by chemical etching, ion etching or photoetching.

9. The method of claim 1, wherein the post is tapered with a thick root and a thin tip.