WO2006096005A1

WO2006096005A1 - Waterproof substrate and method for fabricating the same

Info

Publication number: WO2006096005A1
Application number: PCT/KR2006/000810
Authority: WO
Inventors: Jae Yong Oh
Original assignee: Microhole Co., Ltd.
Priority date: 2005-03-08
Filing date: 2006-03-08
Publication date: 2006-09-14
Also published as: KR100599764B1

Abstract

The present invention relates to a waterproof substrate, and an object of the present invention is to provide a waterproof substrate capable of blocking a liquid such as water and transmitting matter waves and gases such as gas, sound waves and light through a micrometer-sized minute hole. To this end, the waterproof substrate of the present invention comprises micro holes that has pores of size on the order of micrometers and penetrates through both surfaces of the waterproof substrate, wherein a portion of a surface of the waterproof substrate at least in the vicinity of the minute hole is made of a hydrophobic material. Additionally, at least one of the both surfaces of the waterproof substrate is formed with protrusions around the minute hole. With the lotus effect due to the protrusions, it is possible to realize super water-repellency of the waterproof substrate itself.

Description

WATERPROOF SUBSTRATE AND METHOD FOR FABRICATING THE SAME

Technical Field

[1] The present invention relates to a waterproof substrate and a method for fabricating the same, and more particularly, to a waterproof substrate capable of blocking a liquid such as water and transmitting matter waves and gases such as sound waves, gas and light therethrough, and a method for fabricating the same. Background Art

[2] Waterproof cloth has been widely used as a material capable of blocking water and transmitting air and the like therethrough. Such waterproof cloth is made in the form of fabrics using waterproofed yarns and is used limitedly in the field of clothes such as tents, umbrellas, gloves, hats and shoes that require waterproofness.

[3] Recently, with the rapid development of information technology, particularly mobile communication technology, there have been attempts to apply waterproofing technology to information equipment, particularly mobile communication equipment. A typical example is studies on waterproofness of mobile terminals in water. Disclosure of Invention Technical Problem

[4] Conventional waterproof cloth has difficulty in maintain waterproofness in water in which water pressure exists and thus is hardly applicable to mobile terminals and the like. Therefore, there has been proposed a technique for waterproofing a portion, which requires waterproofness, with rubber or silicone sealing.

[5] However, in such a conventional technique, the reliability of waterproofness is lowered and matter waves and gases such as sounds are also blocked together with water. Thus, there is a limitation in that the technique cannot be applied to speakerphones or microphones of mobile terminals.

[6] Accordingly, the inventor has invented a waterproof substrate that is particularly suitable for ensuring the waterproofness of a mobile terminal in water and can be widely used for waterproofing in a variety of industrial fields. Technical Solution

[7] Accordingly, an object of the present invention is to provide a waterproof substrate capable of blocking a liquid such as water and transmitting matter waves and gases such as gas, sound waves and light through minute holes on the order of micrometers.

[8] Another object of the present invention is to provide a waterproof substrate capable of blocking a liquid such as water and transmitting matter waves and gases such as gas, sound waves and light through minute holes on the order of micrometers, wherein the liquid such as water can be more reliably blocked by means of the lotus effect.

[9] A further object of the present invention is to provide a method for fabricating a waterproof substrate formed with minute holes on the order of micrometers.

[10] To achieve these objects, a waterproof substrate of the present invention comprises micro holes that has pores of size on the order of micrometers and penetrates through both surfaces of the waterproof substrate, wherein a portion of a surface of the waterproof substrate at least in the vicinity of each of the holes is made of a hydrophobic material. Thus, the waterproof substrate blocks passage of water and permits passage of only matter waves and gases such as light, gas and a sound through each of the holes.

[11] Here, each hole has pores of size on the order of micrometers, preferably 1 to 10OD, more preferably about 50D. If the size of each hole of the waterproof substrate is less than ID, the transmittance of the matter waves and gases such as a sound, light and gas is remarkably lowered and processability for forming each hole is also deteriorated. Further, if the size of the hole of the waterproof substrate is greater than 10OD, water can easily pass through the hole, resulting in a deteriorated waterproofing function.

[12] It is preferred that the entire waterproof substrate be made of a hydrophobic material with a contact angle of 90 degrees or more with respect to water. Alternatively, the waterproof substrate may be configured by at least partially coating a substrate body, which has a contact angle of less than 90 degrees with respect to water, with a hydrophobic material having a contact angle of 90 degrees or more with respect to water.

[13] Particularly, in the waterproof substrate of the present invention, at least one of the both surfaces of the waterproof substrate is formed with protrusions around the hole. Thus, reliable waterproofing can be achieved by means of the lotus effect due to the minute protrusions. At this time, the minute protrusions preferably have a few to several tens of nanometers. However, with only the formation itself of the nanometer- or micrometer-sized minute protrusions, the hydrophobicity of the waterproof substrate can be improved. More specifically, it can contribute to the super water-repellency of the waterproof substrate.

[14] In the waterproof substrate of the present invention, it is preferred that a plurality of holes be formed in an array.

[15] Meanwhile, according to an aspect of the present invention, a waterproof substrate may be fabricated by preparing a substrate material with a thickness on the order of micrometers; and radiating a laser beam onto the substrate material to form micro holes with pores of size of 1 to 10OD, wherein burrs produced during the step of radiating the laser beam are adapted to be nano-sized minute protrusions. [16] Alternatively, a waterproof substrate of the present invention may be fabricated by preparing a substrate material with a thickness on the order of micrometers; radiating a laser beam onto the substrate material to form micro holes with pores of size of 1 to 10OD; and performing an embossing process on a portion of the waterproof substrate around each of the micro holes using a stamp or roller with a surface having nano- sized recesses formed therein so as to form minute protrusions around each of the holes

[17] Alternatively, a waterproof substrate of the present invention may be fabricated by preparing a plate-shaped plating mold including a conductive region and a non- conductive region; performing metal plating on the plating mold to form a metallic substrate material having micro holes with pores of size of 1 to IOOD and a thickness on the order of micrometers; and separating the metallic substrate material from the plating mold.

[18] Alternatively, a waterproof substrate of the present invention may be fabricated by preparing a photosensitive substrate material in advance; placing a photomask on a surface of the substrate material, and radiating a beam, which responds to the substrate material, onto an exposed portion of the substrate material; and etching the portion subjected to the radiation of the beam so as to form micro holes with pores of size of 1 to IOOD in the substrate material.

[19] Alternatively, a waterproof substrate of the present invention may be fabricated by preparing a substrate material in advance; forming a photosensitive film on a surface of the substrate material, and placing a photomask on the photosensitive film; radiating a beam onto an exposed portion of the photosensitive film, and etching the portion subjected to the radiation of the beam; and etching a portion of the substrate material corresponding to the etched portion of the photosensitive film so that the etched portion of the substrate material can be formed into micro holes with pores of size of 1 to IOOD.

[20] Alternatively, a waterproof substrate of the present invention may be fabricated by preparing a substrate material in advance; forming respective photosensitive films on both surfaces of the substrate material, and placing respective photomasks on the photosensitive films; radiating beams onto exposed portions of the photosensitive films, and etching the portions subjected to the radiation of the beams; and etching portions of the both surfaces of the substrate material corresponding to the etched portions of the photosensitive films so that the etched portions of the substrate material can communicate with each other to form micro holes with pores of size of 1 to IOOD.

[21] Alternatively, a waterproof substrate of the present invention may be fabricated by melting a powder- or pellet-type substrate material at a predetermined temperature; injection molding the molten substrate material into a micro mold; and separating a waterproof substrate, which has micro holes with pores of size of 1 to IOOD, molded in the micro mold from the micro mold.

[22] Alternatively, a waterproof substrate of the present invention may be fabricated by preparing a film-shaped substrate material; and performing compression molding on the substrate material using a hot stamp to form a waterproof substrate having micro holes with pores of size of 1 to 10OD.

[23] Alternatively, a waterproof substrate of the present invention may be fabricated by preparing a film-shaped substrate material; and performing compression molding on t he substrate material using a hot stamp with a surface having minute convexo-concave portions so as to form a waterproof substrate having micro holes with pores of size of 1 to 10OD.

[24] Alternatively, a waterproof substrate of the present invention may be fabricated by placing a liquid substrate material on a support; and pressing the liquid substrate material using a stamp so that a waterproof substrate can have micro holes with pores of size of 1 to 10OD.

[25] Alternatively, a waterproof substrate of the present invention may be fabricated by placing a liquid photocurable substrate material on a support; pressing the substrate material using a stamp to mold a waterproof substrate having micro holes with pores of size of 1 to 10OD; and curing the molded waterproof substrate by radiating light thereon.

[26] Alternatively, a waterproof substrate of the present invention may be fabricated by placing minute protrusions or a silkscreen on a support; and applying a liquid substrate material to the protrusions or silkscreen on the support and curing the substrate material to mold a waterproof substrate having micro holes with pores of size of 1 to 10OD.

[27] Alternatively, a waterproof substrate of the present invention may be fabricated by pouring a liquid substrate material into a micro mold; and curing the substrate material to mold a waterproof substrate having micro holes with pores of size of 1 to 10OD.

Advantageous Effects

[28] The waterproof substrate proposed by the present invention performs the function of blocking introduction of a liquid such as water or a drop of the liquid but selectively transmitting matter waves and gases such as gas, light, sound waves and electromagnetic waves therethrough, and is widely applicable to various kinds of sensors such as waterproof gas sensors requiring a waterproofing function; waterproof speakers, waterproof microphones, waterproof batteries, waterproof cases and the like employed in various electrical appliances such as mobile phones, PDAs, digital cameras, earphones, MP3 players, microphones, telephones, computers, and notebook computers; and a variety of industrial fields such as waterproof clothes, waterproof helmets, waterproof handie talkies, waterproof radio waves/sound waves transceivers, and waterproof wrappers.

[29] In addition, since the waterproof substrate of the present invention has mi crometer- sized minute holes and minute protrusions therearound, there are advantages in that the minute protrusions enable reliable waterproofing by means of the lotus effect and the self-purification capability of the minute protrusions due to the lotus effect avoids contamination with water, liquids or other contaminants.

Brief Description of the Drawings

[30] The above and other objects, features and advantages of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which: [31] Figs. 1 (a) and (b) are a plan view and a sectional view schematically showing a waterproof substrate according to the present invention, respectively; [32] Figs. 2 (a) to (e) are schematic views illustrating waterproofness of the waterproof substrate according to the present invention and transmittance thereof for matter waves and gases;

[33] Fig. 3 is a sectional view schematically showing a waterproof substrate with a hydrophobic material coating formed on a hydrophilic substrate body according to another embodiment of the present invention; [34] Fig. 4 is an enlarged microscopic photograph of a waterproof substrate according to an embodiment of the present invention, showing minute holes and minute protrusions therearound formed in the waterproof substrate;

[35] Fig. 5 is an enlarged photograph showing the minute protrusions in Fig. 4;

[36] Fig. 6 is an enlarged photograph showing minute protrusions formed through an embossing process according to another embodiment of the present invention; [37] Fig. 7 is a view showing that the waterproof substrate of the present invention blocks water and allows matter waves and gases to be transmitted therethrough; [38] Figs. 8 and 9 are views illustrating a method for fabricating a waterproof substrate using a laser beam; [39] Figs. 10 and 11 are views illustrating a method for fabricating a waterproof substrate by means of plating; [40] Figs. 12 to 14 are views illustrating a method for fabricating a waterproof substrate by means of etching; [41] Fig. 15 is a view illustrating a method for fabricating a waterproof substrate by means of injection molding; [42] Figs. 16 to 19 are views illustrating a method for fabricating a waterproof substrate by means of compression molding using a stamp; [43] Fig. 20 is a view illustrating a method for fabricating a waterproof substrate by means of silkscreen;

[44] Fig. 21 is a view illustrating a method for fabricating a waterproof substrate by means of casting; and

[45] Figs. 22 to 25 are exemplary views showing a variety of configurations of a waterproof substrate according to the present invention. Best Mode for Carrying Out the Invention

[46] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[47] Fig. 1 (a) is a plan view of a waterproof substrate, and Fig. 1 (b) is a sectional view of the waterproof substrate of Fig. 1 (a) taken along line I-I.

[48] As shown in Figs. 1 (a) and (b), a waterproof substrate of this embodiment has a thickness t of several tens of micrometers, preferably about 50D, and has minute holes with pores of size d of 1 to 10OD, preferably several tens of micrometers, more preferably about 50 Dtherein. These minute holes 10 are formed to penetrate through the waterproof substrate 1 and permits passage of matter waves and gases such as a sound therethrough.

[49] In this embodiment, the waterproof substrate 1 is made of a hydrophobic material with a contact angle of 90 degrees or more with respect to water. Therefore, the waterproof substrate 1 prevents a liquid such as water from passing through the minute holes 10 by means of its own hydrophobicity of the surface thereof and the micrometer size of the minute holes 10.

[50] Figs. 2 (a) to (e) are views illustrating the material wave transmittance and water- proofness of the waterproof substrate 1 according to this embodiment. As shown in Figs. 2 (a) and (b), the waterproof substrate 1 of this embodiment blocks passage of water or water drops through the minute holes 10. This is enabled by the hydrophobic surface of the waterproof substrate 1 that functions to expel water passing through the minute holes 10. As shown in Figs. 2 (c) to (e), the waterproof substrate 1 of this embodiment permits passage of matter waves and gases such as gas, light or electromagnetic waves, and sound waves through the minute holes 10. Thus, the waterproof substrate 1 can be advantageously used for different apparatuses in a variety of industrial fields that require selective passage of the matter waves and gases such as gas, light or electromagnetic waves, and sound waves therethrough while blocking inflow of a liquid such as water.

[51] Fig. 3 illustrates a waterproof substrate 1 according to another embodiment of the present invention, which comprises a substrate body 2 made of a hydrophilic material and a hydrophobic coating layer 3 coated on the substrate body 2. In this waterproof substrate 1, the coating layer 3 is formed at least in the vicinity of minute holes 10, par- ticularly around the minute holes 10 and on inner surfaces of the minute holes 10. The most preferable method for fabricating such a waterproof substrate 1 is a method comprising the steps of first forming minute holes with pores of size of a few to several tens of micrometers in the substrate body 2, and coating the coating layer 3 made of a hydrophobic material on an entire surface of the substrate body 2.

[52] Fig. 4 and Figs. 5 and 6 are photographs showing various examples of the waterproof substrate fabricated according to the present invention. Fig. 4 is a photograph showing micro holes with a diameter of 1OD formed in the waterproof substrate and nano-sized minute protrusions formed therearound, Fig. 5 is an enlarged photograph of the minute protrusions of Fig. 4, and Fig. 6 is an enlarged photograph of another type minute protrusions formed by means of embossing or the like.

[53] The waterproof substrate with the minute protrusions shown in Figs. 4 to 6 exhibits stronger hydrophobicity with respect to water drops by means of the lotus effect, i.e., super-hydrophobicity with a contact angle of 150 degrees or more with respect to water. This is implemented by the hydrophobic minute protrusions that are formed around the minute holes and greatly reduce a contact area between the waterproof substrate and the liquid.

[54] The lotus effect was found by Wilhelm Barthlott who is a German botanist and first described the phenomenon in which, when a water drop falls onto a lotus leaf, the water drop remains as it is on the lotus leaf. WO 9604123, WO 0058415, WO 0058410 and the like filed and published in the name of Wilhelm Barthlott disclose a self- purification method using the lotus effect, and the like.

[55] Meanwhile, in the waterproof substrate including the minute holes and the minute protrusions around the minute holes according to the present invention, the minute protrusions 20 minimize the contact area between the waterproof substrate 11 and water, so that passage of the water through the minute holes 10 can be more strictly blocked while passage of a sound through the minute holes 10 is advantageously permitted, as shown in Figs. 7 (a) and (b).

[56] The waterproof substrate 1 with the minute protrusions 20 can be fabricated through various methods. Hereinafter, various embodiments for fabricating the waterproof substrate 1 will be described.

[57] <First fabrication method of waterproof substrate using laser beam processing>

[58] Fig. 8 illustrates a method for fabricating a waterproof substrate using laser beam processing according to the present invention.

[59] As illustrated in Fig. 8, the method for fabricating a waterproof substrate comprises radiating a laser beam B on a film-shaped substrate material S, which is wound around a pair of feeding rolls 110 and continuously fed onto a processing bed 120, thereby forming minute holes 10 (see Fig. 7) with pores of size of about 1 to IOOD in the substrate material S.

[60] The laser beam B is radiated from a laser oscillator 140 installed above the processing bed 120. One or more laser beams B radiated from the laser oscillator 140 burn some portions of the substrate material S, thereby forming the minute holes 10 as well as minute, preferably nanometer-sized, burrs (see Figs. 5 and 6) around the minute holes 10. These burrs are produced without additional processing when some portions of the substrate material S are burned, and constitute the minute protrusions as shown in Figs. 4 and 5.

[61] At this time, the substrate material may be cut into a predetermined length in advance and then fed while being displaced on a conventional conveyor instead of the aforementioned pair of feeding rolls, or may be considered to be fed while being fixed to the conveyor in order to accurately feed the substrate material. Further, in order to reduce a processing error that may be produced through laser processing, the substrate material may be fixed using a vacuum chuck or pressing chuck and then subjected to laser beam processing. Moreover, in order to obtain a clearer surface, which has been processed using the laser beam, around the minute holes, a heating or cooling system may be installed for the substrate material. Alternatively, it is possible to consider constructing an inert atmosphere such as a nitrogen or argon atmosphere around the substrate material. For shape recognition of the substrate material to be processed, a vision system for shape recognition may be installed around a portion of the substrate material to be processed. To inspect the substrate material or waterproof substrate in real time before, during or after processing, a microscope with high magnification may be installed in front of or at the rear of a portion of the substrate material to be processed.

[62] <Second fabrication method of waterproof substrate using laser beam processing>

[63] Fig. 9 is a view illustrating a method for fabricating a waterproof substrate by simultaneously performing laser beam processing for forming minute holes and embossing processing for forming additional minute protrusions around the minute holes.

[64] As illustrate in Fig. 9, the method for fabricating a waterproof substrate according to this embodiment comprises the step of consecutively performing the laser beam processing and the embossing processing on a substrate material S fed by a pair of feeding rolls 110. That is, minute holes are formed in the substrate material S using a laser beam B radiated by a laser oscillator 140 and additional and artificial minute protrusions are further formed around the minute holes using a stamp type embossing system 150 or a roller type embossing system 160 while feeding the substrate material S with the minute holes formed therein. At this time, these minute protrusions are formed in addition to the aforementioned minute protrusions in the form of burrs. The method for fabricating a waterproof substrate according to this embodiment allows a manufacturer to determine the shape and size of the minute protrusions.

[65] The aforementioned stamp-type embossing system 150 and roller-type embossing system 160 are selectively used for various waterproof substrate fabricating methods, which will be described later, in addition to the waterproof substrate fabricating method using the laser beam processing, thereby enabling the minute protrusions shown in Fig. 6 to be selectively formed around the minute holes upon fabrication of the waterproof substrate.

[66] <First fabrication method of waterproof substrate by means of plating>

[67] Figs. 10 (a) to (c) illustrate a method for fabricating a waterproof substrate by means of plating according to the present invention. The method for fabricating a waterproof substrate according to this embodiment comprises the steps of preparing a plate- shaped plating mold 200 including conductive regions A and nonconductive regions B as shown in Fig. 10 (a), performing metal plating on the plating mold 200 as shown in Fig. 10 (b), and separating a waterproof substrate 1, which has been obtained by means of the metal plating, from the plating mold 200 as shown in Fig. 10 (c).

[68] The plating mold 200 is formed to have a top surface with the conductive regions A and the nonconductive regions B. These conductive regions A and nonconductive regions B are formed in such a manner that a plurality of nonconductors 220 with a plurality of protrusions are attached to a top surface of a conductive plate, preferably a metal plate 210 while being spaced apart from one another.

[69] As illustrated in Fig. 10 (b), plating, preferably electroplating is performed on the plating mold 200, and metal is grown on the conductive regions A existing between the adjacent nonconductive regions B to form a plated layer P. The plated layer P includes portions that have not been plated due to the presence of the nonconductive regions B. Further, the plated layer P extends toward some portions of the nonconductive regions B. At this time, the plated layer P is formed with minute protrusions 20 by means of protrusions existing in the nonconductive regions B.

[70] Thereafter, as shown in Fig. 10 (c), the plated layer is separated from the plating mold 20 to form a single waterproof substrate 1 in which the non-plated portions define minute holes 10 and the minute protrusions 20 are formed around the minute holes 10.

[71] At this time, the size of the minute holes 10 can be approximately determined by a manufacturer based on the size of the nonconductive regions B and plating time, and the size and shape of the minute protrusions 20 are determined according to the size and shape of the protrusions of the nonconductive regions B.

[72] If the waterproof substrate 1 itself obtained as above is made of a hydrophilic material, the surface thereof is coated with a hydrophobic material, thereby being completely fabricated.

[73] <Second fabrication method of waterproof substrate by means of plating>

[74] Figs. 11 (a) to (d) illustrate a method for fabricating a waterproof substrate by preparing a plating mold using an inlay technique and performing plating on the plating mold.

[75] The method for fabricating a waterproof substrate comprises the step of preparing the plating mold 200 by forming recesses 212 in a top surface of a conductive plate 210 as shown in Fig. 11 (a) and filling the recesses 212 with nonconductors 220. More specifically, a nonconductive molten polymer is filled into the recesses 212 formed in the conductive plate 210, and the molten polymer is then cured to form the plating mold 200 as shown in Fig. 11 (b). Thereafter, a plated layer P is formed as shown in Fig. 11 (c) and then separated from the plating mold 200. Accordingly, it is possible to obtain a waterproof substrate 1 as shown in Fig. 11 (d).

[76] As described above, in the plating mold 200 prepared by means of the inlay technique, the nonconductive regions B and the conductive regions A define an identical plane so that conductors and nonconductors can be more firmly coupled with each other and the nonconductors can be very easily separated from the conductive plate. Further, the surface of the plating mold 200 is regenerated through a chemical mechanical polishing (CMP) or etching process so that the plating mold can be reused for fabrication of the waterproof substrate 1, resulting in excellent recyclability.

[77] The conductive plate 210 is not necessarily made of a metallic material but may have a structure in which a conductive material is coated on various kinds of non- conductive materials such as polymers, glass, rubber, ceramic, silicone, PCB, and plastics.

[78] As for a plating material for the waterproof substrate 1, various metallic materials such as copper, nickel, iron, SUS (stainless alloy), aluminum and metal alloys can be used.

[79] <First fabrication method of waterproof substrate by means of etching>

[80] Fig. 12 shows another example of a method for fabricating a waterproof substrate by means of etching.

[81] As shown in Fig. 12, the method for fabricating a waterproof substrate according to this embodiment fabricates a waterproof substrate 1 by radiating a microwave beam onto a photosensitive substrate material S, i.e., a photosensitive polymer substrate or photosensitive glass substrate that responds to the microwave beam, and by etching portions with modified properties due to the radiation of the microwave beam to form minute holes 10 with pores of size of 1 to 10OD.

[82] More specifically, the method for fabricating a waterproof substrate according to this embodiment comprises placing a photomask P, which has holes corresponding to the minute holes 10 to be formed later, on a surface of the photosensitive substrate material S, and radiating the microwave beam such as UV rays, an electron beam or X- rays onto the photosensitive substrate material S through the holes of the photomask P. Portions of the photosensitive substrate material S that have responded to the microwave beam have had modified properties and thus can be easily etched by an etchant. The etched portions form the minute holes 10 in the waterproof substrate.

[83] <Second fabrication method of waterproof substrate by means of etching>

[84] Fig. 13 shows a further example of a method for fabricating a waterproof substrate by means of etching.

[85] As shown in Fig. 13, the method for fabricating a waterproof substrate according to this embodiment fabricates a waterproof substrate 1 by preparing a substrate material S with a predetermined thickness in advance, stacking an etching mask T and a photosensitive film C on the substrate material S, placing a photomask P thereon, radiating a microwave beam onto the photosensitive film C and the etching mask T through holes of the photomask P, etching portions of the photosensitive film C and the etching mask T that have had modified properties due to the radiation of the microwave beam, and dry-etching or wet-etching the substrate material S through a pattern formed by means of the etching of the photosensitive film C and the etching mask T so as to form minute holes 10 with pores of size of 1 to IOOD in the substrate material.

[86] At this time, contrary to the previous embodiment, the substrate material S is not needed to be a photosensitive substrate material.

[87] Moreover, although the etching mask T has been used in this embodiment, it is also possible to etch the substrate material S for fabrication of the waterproof substrate 1 only with patterning of the photosensitive film C without the etching mask T.

[88] <Third fabrication method of waterproof substrate by means of etching>

[89] Fig. 14 shows a still further example of a method for fabricating a waterproof substrate by means of etching.

[90] The method for fabricating a waterproof substrate according to this embodiment fabricates a waterproof substrate 1 by performing a patterning process and an etching process on both surfaces of a substrate material S so as to form minute holes 10 with pores of size of 1 to IOOD, which vertically communicate with each other, in the substrate material S.

[91] To this end, the method for fabricating a waterproof substrate according to this embodiment forms the vertically communicating minute holes 10 in the substrate material S by applying photosensitive films C on the both surfaces of the substrate material S, placing photomasks P on the photosensitive films C, etching exposed portions of the photosensitive films C, which have responded to the microwave beam, so as to pattern the both surfaces of the substrate material S, and simultaneously etching the both surfaces of the substrate material S along the pattern.

[92] According to the method for fabricating a waterproof substrate by etching the both surfaces of the substrate material S, it is possible to change the sectional shape of the minute holes 10 into various shapes. The change in the sectional shape of the minute holes 10 can contribute to improvement of hydrophobicity of the waterproof substrate 1.

[93] <Fabrication method of waterproof substrate by means of injection molding>

[94] Fig. 15 shows an example of fabricating a waterproof substrate of the present invention by means of injection molding.

[95] As shown in Fig. 15, the method for fabricating a waterproof substrate according to this embodiment fabricates a waterproof substrate with a plurality of minute holes formed therein by melting and feeding pellet-shaped substrate materials F, preferably pellet-shaped polymers using a heating screw 310, and by injection-molding the melted and fed substrate materials within a micro mold 320. At this time, the micro mold is designed to form a thin plate-shaped sheet having minute holes with pores of size of 1 to 10OD. It is preferred that the interior of the micro mold 320 be coated with a release agent for enabling easy separation of the molded waterproof substrate from the micro mold.

[96] <First fabrication of waterproof substrate by means of compression molding>

[97] Figs. 16 (a) and (b) illustrate a method for fabricating a waterproof substrate by performing compression molding on a film-shaped substrate material S.

[98] As illustrated in Fig. 16 (a), the film-shaped substrate material S, preferably a film- shaped substrate material S made of a polymer is fed on a support 420 by a pair of feeding rolls 410, and a hot stamp 430 is lowered with high pressure toward the film- shaped substrate material S stopped on the support 420 so that the stamp 430 can form minute holes with pores of size of 1 to IOOD in the film-shaped substrate material S. Accordingly, a waterproof substrate is fabricated.

[99] At this time, the stamp has a pressing surface 432 with a minute convexo-concave structure and is maintained at a high temperature at which the substrate material S can be molded. With the convexo-concave structure, the substrate material S is formed with a plurality of minute holes.

[100] As illustrated in Fig. 16 (b), a waterproof substrate is fabricated by forming minute holes with pores of size of 1 to IOOD in the film-shaped substrate material S by means of rotation of a roller 440 instead of the vertically moving stamp 430. At this time, the surface of the roller 442 is formed with minute convexo-concave portions so that a plurality of minute holes can be formed in the substrate material S.

[101] <Second fabrication of waterproof substrate by means of compression molding>

[102] Fig. 17 illustrates a method for fabricating a waterproof substrate by performing compression molding on a liquid substrate material M.

[103] As illustrated in Fig. 17, the method for fabricating a waterproof substrate according to this embodiment comprises placing a molten substrate material or liquid substrate material M composed of thermoplastic resin on a support 520, and lowering a stamp 530 thereon to fabricate a waterproof substrate having minute holes with pores of size of 1 to IOOD by means of a downward force of the stamp 530 under high pressure.

[104] <Third fabrication of waterproof substrate by means of compression molding>

[105] Fig. 18 illustrates a method for fabricating a waterproof substrate by performing compression molding on a liquid substrate material M composed of photocurable resin.

[106] As illustrated in Fig. 18, the method for fabricating a waterproof substrate according to this embodiment comprises placing a liquid photocurable substrate material M, which is curable in response to light, on a support 620, molding a waterproof substrate using a stamp 630, and radiating light for curing the photocurable substrate material onto the photocurable substrate material, which is being or has been subjected to molding, using a light source 640 installed around the support 620, particularly below the support 620, thereby molding and curing the waterproof substrate.

[107] Fig. 19 shows a stamp 730 with a structure particularly suitable for the aforementioned compression molding of the waterproof substrate. The stamp 730 is formed such that a pressing surface 732 thereof to be pressed against the waterproof substrate has a predetermined radius of curvature, thereby allowing the liquid substrate material M to be smoothly spread and molded on a support 720.

[108] <Fabrication of waterproof substrate by means of silkscreen or the like>

[109] Fig. 20 illustrates a method for fabricating a waterproof substrate by means of silkscreen or the like.

[110] As illustrated in Fig. 20, the method for fabricating a waterproof substrate according to this embodiment fabricates a waterproof substrate of the present invention by placing a net-shaped silkscreen 810 with a plurality of meshes on a support 820, applying a liquid substrate material M, particularly a molten polymer on the support 820 with the silkscreen placed thereon, filling the meshes with the liquid substrate material M using a resilient push stick 830, solidifying the substrate material M through heat treatment or light radiation thereon to mold the waterproof substrate 1 having minute holes 10 with pores of size of 1 to IOOD, and separating the waterproof substrate 1 from the support 820 with the silkscreen 810 placed thereon. Here, it is preferred that a release agent be coated on the surface of the support and/or the silkscreen so that the molded waterproof substrate 1 can be easily separated from the support 820 and the silkscreen 810.

[I l l] At this time, although this embodiment has been described as forming one mold for use in molding the waterproof substrate by placing the silkscreen 810 on the support 820, it is also possible to fix a plurality of minute protrusions on the support so that the support with the minute protrusions fixed thereto can form one mold. Further, a die coating process for compactly filling a mold with a liquid substrate material can be applied to the present invention.

[112] <Fabrication of waterproof substrate by means of casting>

[113] Fig. 21 illustrates a method for fabricating a waterproof substrate by means of casting according to the present invention.

[114] As illustrated in Fig. 21, the method for fabricating a waterproof substrate according to this embodiment fabricates a waterproof substrate using a mold 920 that is formed to have a depth of several tens of micrometers and protrusions of several tens of micrometers. To this end, a liquid substrate material M is filled into the mold 920 and then solidified through heat treatment or light radiation, and a molded waterproof substrate is separated from the mold 920, thereby fabricating a waterproof substrate 1 with minute holes 10 formed therein.

[115] <Various modified examples of waterproof substrate for improvement of waterproofing function>

[116] Figs. 22 (a) to (c) show different waterproof substrates 1 with predetermined arrays of a plurality of minute holes 10 arranged therein.

[117] The minute holes 10 shown in Figs. 23 (a) to (1) may have various shapes such as a triangle, an ellipse, a gear and a star, in addition to the minute holes 10 in the form of a circle, a square and a regular hexagon shown in Fig. 22.

[118] Further, the waterproof substrate 1 of the present invention may have various sectional shapes as shown in Figs. 23 and 24 in order to improve a waterproofing function. Moreover, the waterproof substrate 1 of the present invention may also include minute protrusions with various shapes shown in Figs. 25 (a) to (j) around the minute holes 10.

[119] Materials for the waterproof substrate of the present invention may include various polymers such as poly methyl methacrylate (PMMA), poly carbonate (PC), poly vinylidene fluoride (PVDF), polydimethylsiloxane (PDMS), cyclic olefin copolymer (COC), SU-8 (photoresist), PR (photoresist coating agent), Teflon, nylon, polyester, polyvinyl, Kapton, and silicone rubber; various inorganic materials such as glass, quartz, silicone and ceramic; various metals and alloys such as copper, nickel, iron, stainless alloys (SUS), aluminum and magnesium; and other materials such as paper and Styrofoam existing in a solid state at room temperature. Industrial Applicability

[120] Although the present invention has been described in connection with the specific embodiments, it will be understood that various adaptations, modifications and changes can be made thereto in the art within the spirit and scope of the present invention defined by the appended claims. Therefore, the description and drawings should be construed as illustrating the present invention rather than limiting the technical spirit of the present invention.

Claims

[1] A waterproof substrate for blocking passage of water and permitting passage of matter waves and gases therethrough, comprising: micro holes with a pore size of micrometers, each of the holes penetrating through both surfaces of the waterproof substrate, wherein a portion of a surface of the waterproof substrate at least in the vicinity of each of the holes is composed of a hydrophobic material and nano-protrusions.

[2] The waterproof substrate as claimed in claim 1, wherein the entire waterproof substrate is made of a hydrophobic material with a contact angle of 90 degrees or more with respect to water.

[3] The waterproof substrate as claimed in claim 1, wherein the waterproof substrate is configured by at least partially coating a substrate body with a hydrophobic material having a contact angle of 90 degrees or more with respect to water, the substrate body having a contact angle of less than 90 degrees with respect to water.

[4] The waterproof substrate as claimed in claim 1, wherein at least one of the both surfaces of the waterproof substrate is formed with protrusions around each of the holes.

[5] The waterproof substrate as claimed in claim 1, wherein the micro holes are formed in an array.

[6] A method for fabricating a waterproof substrate for blocking passage of water and permitting passage of matter waves and gases therethrough, comprising the steps of: preparing a substrate material with a thickness on the order of micrometers; and radiating a laser beam onto the substrate material to form micro holes with a pores size of 1 to 10OD, wherein burrs produced during the step of radiating the laser beam are adapted to be nano-sized minute protrusions.

[7] A method for fabricating a waterproof substrate for blocking passage of water and permitting passage of matter waves and gases therethrough, comprising the steps of: preparing a substrate material with a thickness on the order of micrometers; radiating a laser beam onto the substrate material to form micro holes with pores of size of 1 to 10OD; and performing an embossing process on a portion of the waterproof substrate around each of the holes to form micro protrusions around each of the holes

[8] A method for fabricating a waterproof substrate for blocking passage of water and permitting passage of matter waves and gases therethrough, comprising the steps of: preparing a plate-shaped plating mold including a conductive region and a non- conductive region; performing metal electro plating on the plating mold to form a metallic substrate material having micro holes with pores of size of 1 to IOOD and a thickness on the order of micrometers; and separating the metallic substrate material from the plating mold to fabricate the waterproof substrate.

[9] The method as claimed in claim 8, wherein a plurality of minute protrusions are formed in advance in the nonconductive region so that in the step of performing the metal electro plating, other minute protrusions corresponding to the minute protrusions of the nonconductive region can be formed around each of the micro holes of the metallic substrate material .

[10] The method as claimed in claim 8, wherein the conductive region and the non- conductive region define an identical plane.

[11] A method for fabricating a waterproof substrate for blocking passage of water and permitting passage of matter waves and gases therethrough, comprising the steps of: preparing a photosensitive substrate material in advance; placing a photomask on a surface of the substrate material, and radiating a beam onto an exposed portion of the substrate material, the beam responding to the substrate material; and etching the portion subjected to the radiation of the beam so as to form micro holes with pores of size of 1 to IOOD in the substrate material.

[12] A method for fabricating a waterproof substrate for blocking passage of water and permitting passage of matter waves and gases therethrough, comprising the steps of: preparing a substrate material in advance; forming a photosensitive film on a surface of the substrate material, and placing a photomask on the photosensitive film; radiating a beam onto an exposed portion of the photosensitive film, and etching the portion subjected to the radiation of the beam; and etching a portion of the substrate material corresponding to the etched portion of the photosensitive film so that the etched portion of the substrate material can be formed into micro holes with pores of size of 1 to IOOD.

[13] A method for fabricating a waterproof substrate for blocking passage of water and permitting passage of matter waves and gases therethrough, comprising the steps of: preparing a substrate substrate in advance; forming respective photosensitive films on both surfaces of the substrate material, and placing respective photomasks on the photosensitive films; radiating beams onto exposed portions of the photosensitive films, and etching the portions subjected to the radiation of the beams; and etching portions of the both surfaces of the substrate material corresponding to the etched portions of the photosensitive films so that the etched portions of the substrate material can communicate with each other to form micro holes with pores of size of 1 to 10OD.

[14] A method for fabricating a waterproof substrate for blocking passage of water and permitting passage of matter waves and gases therethrough, comprising the steps of: melting a powder- or pellet- type raw material at a predetermined temperature; injection molding the molten material into a micro mold; and separating a waterproof substrate molded in the micro mold from the micro mold, the molded waterproof substrate having micro holes with pores of size of 1 to 10OD.

[15] A method for fabricating a waterproof substrate for blocking passage of water and permitting passage of matter waves and gases therethrough, comprising the steps of: preparing a film-shaped substrate material; and performing compression molding using a hot stamp or roller to form a waterproof substrate having micro holes with pores of size of 1 to 10OD.

[16] A method for fabricating a waterproof substrate for blocking passage of water and permitting passage of matter waves and gases therethrough, comprising the steps of: placing a liquid substrate material on a support; and pressing the liquid substrate material using a stamp to mold a waterproof substrate having micro holes with pores of size of 1 to 10OD.

[17] A method for fabricating a waterproof substrate for blocking passage of water and permitting passage of matter waves and gases therethrough, comprising the steps of: placing a liquid photocurable material on a support; pressing the material using a stamp to mold a waterproof substrate having micro holes with pores of size of 1 to 10OD; and curing the molded waterproof substrate by radiating light thereon.

[18] A method for fabricating a waterproof substrate for blocking passage of water and permitting passage of matter waves and gases therethrough, comprising the steps of: placing minute protrusions or a silkscreen on a support; and applying a liquid substrate material to the protrusions or silkscreen on the support and curing the material to mold a waterproof substrate having micro holes with pores of size of 1 to 10OD.

[19] A method for fabricating a waterproof substrate for blocking passage of water and permitting passage of matter waves and gases therethrough, comprising the steps of: pouring a liquid substrate material into a micro mold; and curing the material to mold a waterproof substrate having micro holes with pores of size of 1 to 10OD.