JP2010086629A - Ventilation filter, electric device, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ventilation filter having a particle-removing mechanism and capable of completing gas replacement in a casing within a short period of time, and to provide an electric device using the same. <P>SOLUTION: The ventilation filter is configured by stacking a substrate film 1 and a ventilation film 6. The substrate film 1 includes at least two openings: a first opening 2a formed to permit reciprocation gas so as to reduce a difference between the atmospheric pressure of the ventilation film 6 side and the atmospheric pressure of the substrate film 1 side; and a second opening 3 formed to supply gas in a direction from the substrate film 6 side to the ventilation film 1 side or in a direction from the ventilation film 1 side to the substrate film 6 side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a ventilation filter installed in a housing of an electrical device such as a hard disk drive, an electrical device using the ventilation filter, and a method of manufacturing the electrical device.

  The recording density of a hard disk drive (HDD) used as a main storage device such as a computer is increasing year by year. Before HDDs become final products, address information (servo data) is recorded on the disk. To increase the recording position with increasing recording density, disk friction (windage loss) due to air and It is necessary to minimize the effects of heat. Therefore, by replacing the HDD housing with a gas that is lighter than air, such as hydrogen gas or helium (He) gas, it has been conventionally possible to reduce disturbance such as windage loss when servo data is recorded on the disk. Known from.

  Patent Document 1 describes a method of using a test port for particle (dust) inspection as a method of replacing the air in the housing of the HDD with helium gas (Claim 5). However, since this test port is a through hole not covered (protected) by a ventilation filter or the like (FIG. 6), if helium gas or the like is injected into the HDD housing using this test port, helium gas is supplied. There is a possibility that particles existing inside the cylinder or inside the connection tube used for injection or particles generated when the tube is connected enter the case together with the helium gas, and the case is contaminated by the particles.

  On the other hand, as described in FIG. 5 of Patent Document 2, a housing of the HDD is usually provided with a vent hole. A ventilation filter equipped with a filter medium (gas adsorption member) that adsorbs harmful gas, moisture, and the like to the internal mechanism of the HDD is attached to the vent hole. For this reason, even if air expands and contracts due to temperature changes during HDD operation, the structure allows air to enter and exit from the inside and outside of the housing via the vent and the ventilation filter. This keeps the HDD casing breathing clean.

Further, as shown in FIG. 5, it is common to form an elongated passage called a diffusion passage in the ventilation filter in the middle of the gas flow path between the outside air and the HDD. Due to the presence of the diffusion flow path, even when the HDD housing is suddenly brought into a high temperature or high humidity environment, sufficient time can be taken for moisture to reach the inside of the HDD, and condensation and rust can be generated inside the HDD. Is preventing.
JP 2006-40423 A (Claim 5, FIG. 6) JP 2000-33212 A (paragraph 0004, FIG. 5)

  Patent Document 1 describes a method of using a test port for particle inspection as a method for sending a replacement gas into the HDD housing. However, as described above, particles generated in a helium cylinder or during connection work are also simultaneously generated. Since it enters into the housing, it is not a preferable method. Then, as one method capable of sending the replacement gas into the HDD housing while preventing the intrusion of particles, there is a method of sending the replacement gas into the HDD housing via the vent described in Patent Document 2. You can recall. However, the ventilation filter provided in the ventilation hole is provided with a filter medium (gas adsorption member) for capturing moisture, polluted gas, and the like, and thus has high resistance to the passage of gas. That is, the pressure loss of the ventilation filter is high. Further, when the diffusion channel is formed, the pressure loss in the ventilation filter is further increased. Therefore, even if the method of sending the replacement gas into the HDD housing through the vent described in Patent Document 2 as described above is adopted, the pressure loss of the ventilation filter is high, so There is a concern that it takes a long time to send the replacement gas, and the manufacturing tact of the HDD or the like falls.

  In view of the above, in order to simultaneously obtain the two effects of preventing the intrusion of particles in the gas replacement process and completing the gas replacement in the housing in a short time, the patent document 2 discloses a ventilation filter. It is not enough to apply it to Document 1, and it is necessary to consider it one step further.

  In view of the above-described circumstances, the present invention is provided with a ventilation filter that has a particle removal function and that can complete gas replacement in a housing in a short time and does not reduce manufacturing tact, and an electric device using the same ( For example, a hard disk drive is provided.

  The ventilation filter of the present invention that can achieve the above object is a ventilation filter configured by laminating a base film and a ventilation film, and the base film includes an air pressure and a base on the side of the ventilation film. A first opening that allows gas to flow in order to relieve a difference from the pressure on the material film side, and one direction from the base film side to the gas permeable film side, or the base material from the gas permeable film side At least two of the second openings for flowing gas in one direction on the membrane side are formed.

  As the ventilation filter, it is recommended that a gas adsorbent is sandwiched between the base film and the vent film, and the gas adsorbent does not cover the second opening. .

  The ventilation filter of the present invention capable of achieving the above object includes a base film having at least first and second openings, a gas adsorbing member formed so as to cover a part of the base film, And a gas permeable member formed so as to sandwich the gas adsorbing member with the base material membrane, and the second opening is not covered with the gas adsorbing member.

  In the vent filter, it is recommended that a gas flow path is formed in the base film, and one end of the flow path is connected to the first opening.

  In the ventilation filter, it is recommended that the ventilation film is made of a fluororesin film.

  In the above-described ventilation filter, it is recommended that the ventilation membrane is composed of a porous polytetrafluoroethylene membrane.

  In the above-described ventilation filter, it is recommended that the ventilation film is composed of an electret film.

  In the ventilation filter, it is recommended that the ventilation film covering the first opening is a porous polytetrafluoroethylene film, and the second opening is covered with an electret film.

  In the ventilation filter, it is recommended to add a liquid repellent to the surface of the ventilation membrane.

  In the ventilation filter, it is recommended that the base material film is composed of a double-sided adhesive tape.

  In the ventilation filter, it is desirable to further provide a ventilation film between the gas adsorbing member and the base material film.

  The electric device of the present invention that can achieve the above object includes a housing having an opening and the ventilation filter formed so as to cover the opening.

  In the electric device, at least two openings of the housing are formed, and each opening communicates with one of the first and second openings of the ventilation filter. preferable.

  In addition to the opening covered by the ventilation filter, the opening of the electric device preferably has another opening for allowing the gas in the casing to flow out.

  The method for manufacturing an electric device according to the present invention that can achieve the above object includes a step of preparing a casing in which at least two openings are formed, and the respective openings are the first and second openings of the ventilation filter. Mounting the ventilation filter on the inner wall side of the casing so as to communicate with any one of the sections; replacing the gas in the casing using the second opening of the ventilation filter; Sealing the opening of the housing communicating with the second opening with a seal member.

  In the ventilation filter according to the present invention, since the base film is provided with the first opening and the second opening, the gas adsorption member or the diffusion flow path is bypassed and the gas for replacement is quickly permeated. be able to. Therefore, gas replacement in the housing can be performed in a short time while having a function of removing particles and harmful gases.

  Hereinafter, a ventilation filter, an electric device, a manufacturing method thereof (hereinafter, described as an example of a hard disk drive (HDD)), and a manufacturing method of a hard disk drive according to an embodiment of the present invention will be described in detail with reference to the drawings. .

(1) Laminated structure of the ventilation filter FIG. 1 is an explanatory view of the structure of the ventilation filter according to the embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line AA in FIG. As shown in FIGS. 1 and 2, the ventilation filter has a structure in which a base film 1, a flow path cover film 4, a gas adsorption member 5, and a ventilation film 6 are sequentially laminated. The base film 1 is formed with a notch 2 including a first opening 2a, a diffusion channel 2b, and a terminal end 2c, and a second opening 3. As shown in FIGS. 1 and 2, the ventilation filter is provided on the inner wall of the HDD housing 7 in which the third opening 8 and the fourth opening 9 are formed. At this time, the first opening 2a and the third opening 8 communicate with each other, and the second opening 3 and the fourth opening 9 communicate with each other.

  In addition to the gas permeable membrane 6, a gas permeable membrane (not shown) may be further provided between the base material film 1 and the gas adsorbing member 5. With such a configuration, it is possible to prevent particles generated from the gas adsorbing member 5 from dropping off. Further, particles contained in the gas flowing from the base film 1 side can be collected before entering the gas adsorbing member 5. As the gas permeable membrane, for example, a porous polytetrafluoroethylene membrane and a non-woven fabric can be used. The same applies to the modes of FIGS.

  Next, the flow of gas passing through the first opening 2a and the third opening 8 will be described. In FIG. 1, the gas that has entered from the outside of the housing 7 (the lower side in FIG. 1) through the third opening 8 of the housing 7 is vented from the first opening 2 a of the base film 1. It flows into the filter, passes through the diffusion flow path 2b, and flows to the end portion 2c. From the end portion 2 c, the gas exits through the gas adsorbing member 5 and the gas permeable membrane 6 to the inside of the housing 7 (upper side in FIG. 1). The gas can also flow in the opposite direction, and from the gas permeable membrane 6 to the casing 7 through the gas adsorbing member 5, the terminal end 2 c of the notch 2, the diffusion flow path 2 b, and the first opening 2 a. The third opening 8 is configured to be able to escape to the outside world.

  The inflow and outflow of gas through the first opening 2a alleviates the difference between the air pressure on the air permeable membrane side (upper side in FIG. 1) and the air pressure on the base material membrane 1 side (lower side in FIG. 1). It depends on the pressure difference inside and outside the housing 7. For example, when the device inside the HDD is operating, the gas inside the HDD housing 7 is heated and expands, so that the air pressure inside the housing 7 becomes high, and then the gas passes through the first opening 2a. It flows out of the housing 7. On the contrary, when the device inside the HDD is stopped, the temperature inside the housing 7 decreases, so that gas flows into the housing 7 through the first opening 2a.

  The gas flow through the second opening 3 will be described in detail later and will be briefly described here. The second opening 3 is formed of hydrogen gas, nitrogen gas, helium gas (He gas), etc. in one direction from the base film 1 side to the gas permeable film 6 side or from one side of the gas permeable film 6 to the base film 1 side. It is an opening provided for flowing a gas lighter than air.

(2) Gas Replacement Procedure FIGS. 3A to 3C are sectional views of the HDD in a state where the ventilation filter according to the embodiment of the present invention is mounted. The HDD main body stored in the housing 7 is manufactured by a known method. FIG. 3A is a diagram showing a state in which He gas, which is a replacement gas, is injected from the gas supply head 12 before recording servo data on the disk. FIG. 3B is a diagram showing a fourth opening after the He gas replacement. FIG. 9 is a diagram illustrating a state in which the ninth opening 10 and the fifth opening 10 are sealed by a sealing member 14.

  As shown in FIG. 3A, a hard disk body and a magnetic head for recording information on or reading information from the hard disk are arranged inside the housing 7 (no reference numeral). A ventilation filter is attached to the inner wall of the housing 7 as described with reference to FIGS. In addition to the third opening portion 8 and the fourth opening portion 9, the housing 7 contains the gas originally present in the housing 7 when the gas is injected from the fourth opening portion 9. A fifth opening 10 (exhaust port) provided for discharging to the outside of the body 7 is formed.

  As shown in FIG. 3A, the gas supply head 12 is pressed against the fourth opening 9, and He gas is injected from the gas supply head 12 into the housing 7. He gas is sent into the housing 7 via the second opening 3 and the gas permeable membrane 6 of the gas permeable filter. At the same time, the air that originally existed in the housing 7 is discharged so as to be pushed out from the fifth opening 10 or the third opening 8 of the housing 7, thereby replacing the gas. Note that the third opening 8 of the housing 7 may be sealed with the seal member 13 when it is desired to minimize the contamination of the gas adsorbing member 5 with the exhaust gas during the gas replacement.

  When the replacement of the He gas is completed, the fourth opening 9 and the fifth opening 10 become unnecessary, and are sealed by the seal member 14 as shown in FIG. 3B. After the HDD is completed, the seal member 13 is removed in order to allow gas to flow through the third opening 8 of the housing 7 and the first opening 2a of the ventilation filter.

  3A is an example in which He gas is injected into the housing 7 from the gas supply head 12, but the present invention may be widely used in electrical devices other than HDDs as will be described later. In consideration, as shown in FIG. 3C, a method of sucking up the gas in the housing 7 from the gas supply head 12 can also be implemented. In that case, since the replacement gas is sucked into the inside of the housing 7 from the outside through the fifth opening 10, the fifth opening 10 is covered with another gas permeable film 11, and the housing 7 It is desirable to collect particles that try to enter from the outside.

  4A to 4C are cross-sectional views of the HDD in a state in which a ventilation filter according to another embodiment of the present invention is mounted, and are basically the same as those in FIGS. 3A to 3C. 3A to 3C is that the fourth opening 9 and the fifth opening 10 are arranged adjacent to each other, whereby the fourth opening 9 is formed by one seal member 14. And the fifth opening 10 can be sealed. As the seal member 14, a dedicated seal member for the purpose of sealing the opening may be prepared, but it is also possible to seal with a label that represents HDD product information or the like.

(3) Modification of Embodiment The outline of the structure of the ventilation filter according to the embodiment of the present invention has been described above. To summarize, the ventilation filter of the present invention has at least the following (3-1) or (3-2). ) That meet one of the requirements.

(3-1)
A ventilation filter configured by laminating a base film 1 and a ventilation film 6. The base film 1 includes a first opening 2 a that allows gas to flow and a base film 1 side. A ventilation filter in which at least two openings of the second opening 3 for flowing gas in one direction of the gas permeable membrane 6 or in one direction from the gas permeable membrane 6 to the base film 1 are formed.

(3-2)
A base film 1 having at least a first opening 2a and a second opening 3, a gas adsorbing member 5 formed so as to cover a part of the base film 1, and the gas adsorbing member 5 as a base film A ventilation filter that has a gas permeable membrane 6 formed so as to be sandwiched between the gas permeable member 1 and the second opening 3 is not covered with the gas adsorbing member 5.

  As described in the requirement (3-1), the gas replacement is efficiently (rapidly) formed by forming the second opening 3 separately from the first opening 2a that enables the gas to come and go. be able to. The second opening 3 is used as an opening for flowing a gas only in one direction from the base film 1 side to the gas permeable membrane 6 side and from the gas permeable film 6 side to the base film 1 side. Although it may be in any direction, the details will be described later with reference to the drawings. In addition, although the effect of speeding up gas replacement is reliably produced by forming the 2nd opening part 3 which has a pressure loss lower than the pressure loss (conductance) of the 1st opening part 2a, the gas to replace | exchange Is assumed to be performed from both the first opening 2 a and the second opening 3, the second opening is formed in the base film 1 regardless of the pressure loss of the second opening 3. Only by forming 3 can the rate of gas replacement be increased.

  In addition, at least one first opening 2a and at least one second opening 3 are formed in the base film 1, and the first opening 2a and / or the second opening are necessary if necessary. A plurality of 3 may be provided. For example, when a plurality of types of replacement gas are introduced into the housing 7, a plurality of second openings 3 are provided, so that more rapid gas replacement can be performed. For example, when it is desired to use different types of gas adsorbing members 5, a plurality of first openings 2 a can be provided correspondingly.

  Moreover, the flow path cover film 4 is one embodiment when a diffusion flow path is formed in the ventilation film. By providing the flow path cover film 4, the flow path in the ventilation film can be lengthened. Therefore, even when the HDD is suddenly brought into a high-temperature or high-humidity environment, sufficient time is required for moisture to reach the inside of the HDD. It is possible to prevent the occurrence of condensation and rust inside the HDD.

  When the gas adsorbing member 5 is provided, the gas adsorbing member 5 may or may not cover the second opening 3, but if not, the pressure loss of the second opening 3 is small. Therefore, it is more preferable as an embodiment.

  Any material can be used as the base material film 1 as long as it can hold the gas permeable film 6. However, the base material film 1 can be easily attached to the housing 7 by being composed of a double-sided adhesive tape. Details will be described later.

  In the present embodiment, an example in which both the first opening 2a and the second opening 3 are covered with one air-permeable membrane 6 has been described. However, as shown in FIG. 5, the first opening 2a Can be covered with a porous polytetrafluoroethylene film, and the second opening 3 can be covered with a different type of air-permeable film, for example, an electret film (hereinafter referred to as “electret filter 15”). An electret is a material in which a dielectric material, such as a polymer material (fluorine resin, polyolefin resin, polyester resin, etc.) is heated and melted and solidified between electrodes while applying a high direct current voltage thereto. A member in which positive or negative static electricity is charged on the surface of the dielectric material even after removal. Since the filter itself is charged, there is an effect of capturing particles floating in the air by electrostatic force. This effect is continuously exhibited not only during the HDD manufacturing process but also after the HDD is completed and shipped.

  Further, the electret filter 15 is a filter that covers the second opening 3 provided for the purpose of promptly inflowing a replacement gas such as He gas because the pressure loss is remarkably lower than that of the porous polytetrafluoroethylene membrane. Can be said to be more suitable than a porous polytetrafluoroethylene film.

  The collection efficiency of the electret filter 15 is lower than that of the porous polytetrafluoroethylene film (for example, the collection efficiency of particles having a diameter of 0.3 μm is 30 to 40% lower than that of the porous polytetrafluoroethylene film. However, the filter that covers the first opening 2a needs to collect particles at a level contained in the general user's use environment after shipment of the HDD, whereas the filter that covers the second opening 3 Is used for the purpose of gas replacement during the manufacturing process of the HDD. Therefore, it is sufficiently possible to control the particle concentration to a low level, so the low collection efficiency compared to the porous polytetrafluoroethylene membrane is not a big disadvantage in practical use and the pressure loss is low. The benefits of this are greater.

  In the present embodiment, the example in which the gas permeable membrane 6 directly covers the second opening 3 has been described. However, the gas adsorbing member 5 may cover the second opening 3, or the other as shown in FIG. 6. The gas adsorbing member 16 may be covered. As the gas adsorbing member 16, it is preferable to use one having a pressure loss (ventilation resistance) lower than that of the gas adsorbing member 5. The reason why the gas resistance of the gas adsorbing member 16 is desirably low is that, as described above, the second opening 3 is intended to allow the replacement gas to flow in quickly.

  As the gas adsorbing member 16 having a low pressure loss, a nonwoven fabric made of activated carbon fibers, a woven fabric, or a nonwoven fabric containing activated carbon by applying activated carbon can be used. In addition, it is preferable to use a gas adsorption member 16 whose surface is provided with an uneven shape (for example, a groove) to reduce pressure loss.

  Note that the low pressure loss of the gas adsorbing member 16 works in the direction of lowering the adsorption efficiency of harmful gases and the like. However, while the gas adsorbing member 5 is exposed to the general user's use atmosphere after shipment of the HDD, the fourth opening 9 of the housing 7 is sealed by the sealing member 14 after the HDD is manufactured. Therefore, the gas adsorbing member 16 is not exposed to the use environment air. Further, the gas adsorption capacity required for the gas adsorption member 16 is not higher than the gas adsorption capacity required for the gas adsorption member 5. The reason for this is that harmful gases mixed in the helium gas when helium gas is replaced (eg, gas contamination generated from the lubricant used inside the regulator to control the gas flow rate supplied from the helium gas cylinder) ), Or any other material that can remove gas generated from the adhesive or the like present in the housing 7 after the housing 7 is sealed by the seal member 14, and a particularly high adsorption capacity is not required. Therefore, the lower collection efficiency compared to the gas adsorbing member 5 is not as great a demerit in actual use, but a merit (acceleration of gas replacement) due to a low pressure loss is greater.

  In the present embodiment, an example will be described in which a third opening 8 is provided in the housing 7 as an opening used for gas replacement, and a fourth opening 9 is individually provided to ensure air permeability inside and outside the HDD housing. However, the third opening 8 and the fourth opening 9 may be combined into a single large opening that plays both roles of gas replacement and air permeability.

  In the present embodiment, an example in which the ventilation filter is applied to the HDD has been described. However, the housing is not limited to the HDD, and any housing can be used as long as it has a housing and needs to replace the gas inside the housing. Can also be used. For example, it can also be used in an electric device intended to replace an inert gas used in an exposure process in manufacturing a semiconductor element.

(4) Details of each component When using a double-sided pressure-sensitive adhesive tape as the base material film 1, the double-sided pressure-sensitive adhesive tape includes a nonwoven fabric-based double-sided pressure-sensitive adhesive tape made of polyethylene nonwoven fabric, polypropylene nonwoven fabric, nylon nonwoven fabric, etc., PET Base material double-sided adhesive tape, polyimide base material double-sided adhesive tape, nylon base material double-sided adhesive tape, foam (for example, urethane foam, silicone foam, acrylic foam, polyethylene foam) base material double-sided adhesive tape, substrate-less double-sided adhesive tape, etc. Various types can be used.

  Polyethylene, polypropylene, polystyrene, polyimide, or the like can be used as the constituent material of the gas permeable membrane 6, but it is preferably a fluororesin excellent in waterproofness, more preferably porous polytetrafluoroethylene (porous PTFE). It is recommended to use this film. As the microscopic shape of the gas permeable membrane 6, a net shape, a mesh shape, or a porous shape can be used. The porous PTFE film is excellent in waterproofness, and is suitable for the purpose of providing air permeability inside and outside the HDD while preventing intrusion of water droplets, dust, harmful gas, and the like.

  A porous PTFE film is obtained by removing a molding aid from a molded body of a paste obtained by mixing PTFE fine powder with a molding aid, stretching at a high temperature and a high speed, and further firing if necessary. It is obtained. In the case of uniaxial stretching, the nodes (folded crystals) are in the form of thin islands perpendicular to the stretching direction, and the fibrils (linear crystals that are drawn by unfolding the folded crystals by stretching) are connected to connect the nodes. Molecular bundle) is oriented in the stretching direction. And it has a fibrous structure in which spaces defined between fibrils or between fibrils and nodes are holes. In the case of biaxial stretching, the fibrils spread radially, the nodes connecting the fibrils are scattered in islands, and a spider web-like fibrous structure in which there are many spaces defined by the fibrils and the nodes. ing.

  The gas permeable membrane 6 may be a uniaxially stretched porous PTFE film or a biaxially stretched porous PTFE film.

  The gas permeable membrane 6 is preferably used by coating the inner surface of the pores with a liquid repellent polymer. By coating the inner surface of the pores of the gas permeable membrane 6 with a water- and oil-repellent polymer, various contaminants such as body fat, machine oil, and water droplets penetrate or are retained in the pores of the gas-permeable membrane. Can be suppressed. These contaminants deteriorate the trapping characteristics and ventilation characteristics of the gas permeable membrane and cause the function as the gas permeable membrane to be impaired.

  In the claims and in the present specification, “liquid repellent” refers to a substance that has a property or function of repelling liquid, and “liquid repellent” includes “water repellent”, “water repellent”. It includes “oil agent”, “water / oil repellent” and the like. Hereinafter, the water- and oil-repellent polymer will be described as an example.

As the water / oil repellent polymer, a polymer having a fluorine-containing side chain can be used. The details of the water / oil repellent polymer and the method of combining it with a porous PTFE film are disclosed in WO94 / 22928 and the like, and an example thereof is shown below.
As the water / oil repellent polymer, the following general formula (1)

(In the formula, n is an integer of 3 to 13, and R is hydrogen or a methyl group)
A polymer having a fluorine-containing side chain obtained by polymerizing a fluoroalkyl acrylate and / or a fluoroalkyl methacrylate represented by formula (the fluorinated alkyl moiety preferably has 4 to 16 carbon atoms) can be preferably used. . In order to coat the pores of the porous PTFE film using this polymer, an aqueous microemulsion of this polymer (average particle size: 0.01 to 0.5 μm) is added to a fluorine-containing surfactant (eg, ammonium perfluoro). Octanate) is used to impregnate the pores of the porous PTFE film, followed by heating. This heating removes water and the fluorine-containing surfactant, and the polymer having fluorine-containing side chains melts to coat the inner surface of the pores of the porous PTFE film while maintaining the continuous pores. A breathable membrane excellent in water and oil repellency can be obtained.

FIG. 1 is an explanatory diagram of the structure of a ventilation filter according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional view of the ventilation filter of FIG. FIG. 3A is a diagram showing a gas replacement process of the hard disk drive according to the embodiment of the present invention. FIG. 3B is a diagram showing the hard disk drive according to the embodiment of the present invention. FIG. 3C is a diagram showing another gas replacement process of the hard disk drive according to the embodiment of the present invention. FIG. 4A is a diagram showing a gas replacement process of a hard disk drive according to another embodiment of the present invention. FIG. 4B is a diagram showing a hard disk drive according to another embodiment of the present invention. FIG. 4C is a diagram showing another gas replacement process of the hard disk drive according to another embodiment of the present invention. FIG. 5 is a cross-sectional view of a ventilation filter according to another embodiment of the present invention. FIG. 6 is a cross-sectional view of a ventilation filter according to another embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base film 2 Notch part 2a 1st opening part 2b Diffusion flow path 2c Termination part 3 2nd opening part 4 Flow path cover film 5, 16 Gas adsorption member 6 Venting film 7 Housing | casing 8 3rd opening part DESCRIPTION OF SYMBOLS 9 4th opening part 10 Exhaust opening part 11 Ventilation film 12 Gas supply head 13, 14 Seal member 15 Electret filter

Claims (15)

  A ventilation filter configured by laminating a base film and a gas permeable film, wherein the base film is a gas for reducing a difference between the pressure on the gas permeable film side and the pressure on the base film side. And a second opening for flowing gas in one direction from the base film side to the gas permeable membrane side, or from the gas permeable film side to the base film side. A ventilation filter, wherein at least two of the openings are formed.   2. The ventilation filter according to claim 1, wherein a gas adsorption member is sandwiched between the base film and the ventilation film, and the gas adsorption member does not cover the second opening.   A base film having at least first and second openings, a gas adsorbing member formed so as to cover a part of the base film, and the gas adsorbing member are sandwiched between the base film And a gas permeable membrane formed as described above, wherein the second opening is not covered with the gas adsorbing member.   The ventilation filter according to any one of claims 1 to 3, wherein a gas channel is formed in the base film, and one end of the channel is connected to the first opening.   The ventilation filter according to any one of claims 1 to 4, wherein the ventilation film is made of a fluororesin film.   The ventilation filter according to claim 5, wherein the ventilation film is composed of a porous polytetrafluoroethylene film.   The ventilation filter in any one of Claims 1-4 with which the said ventilation film is comprised with the electret film | membrane.   The ventilation filter according to any one of claims 1 to 4, wherein the ventilation film covering the first opening is a porous polytetrafluoroethylene film, and the second opening is covered with an electret film.   The ventilation filter according to any one of claims 1 to 8, wherein a liquid repellent is added to the surface of the ventilation film.   The ventilation filter according to any one of claims 1 to 9, wherein the base film is composed of a double-sided adhesive tape.   The ventilation filter according to any one of claims 2 to 10, wherein a ventilation film is further provided between the gas adsorption member and the base material film.   An electric device comprising: a housing having an opening; and the ventilation filter according to any one of claims 1 to 11 formed so as to cover the opening.   The electrical device according to claim 12, wherein at least two openings of the housing are formed, and each of the openings communicates with one of the first and second openings of the ventilation filter.   In addition to the opening covered by the ventilation filter according to any one of claims 1 to 11, the casing is formed with another opening for allowing the gas in the casing to flow out to the outside. The electric device according to claim 12 or 13.   A step of preparing a housing in which at least two openings are formed, and each of the openings communicates with one of the first and second openings of the ventilation filter according to any one of claims 1 to 11. Mounting the ventilation filter on the inner wall side of the casing as described above, replacing the gas in the casing with the second opening of the ventilation filter, and in the second opening And a step of sealing the opening of the casing in communication with a sealing member.