JP4047755B2 - Acoustic transducer manufacturing method and manufacturing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing an acoustic transducer such as an electret condenser microphone (hereinafter referred to as ECM), and more particularly to reduction in the manufacturing cost of a conductive case for an acoustic transducer.
[0002]
[Prior art]
Many electrical components have a conductive case used for the exterior. As a typical example of an electronic component having such a conductive case, an acoustic transducer such as an ECM is known.
[0003]
In the basic structure of the ECM, a conductive case as an exterior part is used as described above. In general, a resin molded structure for insulation is housed in the conductive case as a built-in component.
[0004]
On the other hand, the structure which provided the resin layer for insulation inside the electroconductive case is also proposed, and such ECM enables size reduction. This type of ECM is disclosed in, for example, Japanese Patent Laid-Open No. 2003-9290 (Patent Document 1).
[0005]
Japanese Patent Laid-Open No. 2002-262395 (Patent Document 2) discloses a technique for removing a part of a resin layer of a conductive case. Since there is a portion that needs to be electrically connected to the inlet opening, the insulating layer in the inlet opening is removed. The insulating layer is removed using a punch or a knife.
[0006]
[Patent Document 1]
JP 2003-9290 A (page 3, FIG. 2)
[Patent Document 2]
JP 2002-262395 A (page 3, FIG. 1)
[Problems to be solved by the invention]
As described above, in the conventionally proposed ECM manufacturing method, the insulating layer of the conductive case is removed by a punch and a knife. However, such a removal method is expensive. There is also a problem that shavings remain as foreign matter.
[0007]
In addition, the insulating layer may be removed by optical thermal processing such as laser. However, there is a problem of cost increase due to labor and equipment costs, and there is a problem that the removed insulating layer remains as a foreign matter. Moreover, in order to ensure a conduction | electrical_connection part, although the method of masking in the formation process of an insulating layer can be considered, this is also disadvantageous in terms of cost.
[0008]
In addition, when conduction at the back of the case is necessary, the insulating layer at the back of the case is removed. However, in the conventional method using punches, knives, etc., it is much more difficult to remove the insulating layer at the back of the case than to remove the insulating layer at the case entrance opening (for example, JP-A-2002-262395). is there.
[0009]
Moreover, even if the insulating layer at the back of the case can be removed, it costs considerable. This is fatal in the field of ECM, where the cost requirements are fairly severe. That is, assume that a small and high-performance ECM can be designed. Then, it is assumed that the ECM requires conduction at the back of the case. In this case, if the above cost problem cannot be solved, it is practically difficult to practically use even though it is excellent in design.
[0010]
Although the ECM has been described above, the same problem can occur in an acoustic transducer other than the ECM.
[0011]
The present invention has been made under the above-described background, and an object thereof is to provide a method and an apparatus for manufacturing an acoustic transducer capable of removing an insulating layer at the back of a case at a low cost.
[0012]
[Means for Solving the Problems]
In order to solve the above problems, the acoustic transducer manufacturing method of the present invention is: An acoustic transducer manufacturing method including a step of removing an insulating layer provided on a conductive case for an electret condenser microphone that is an acoustic transducer, wherein the conductive case for the electret condenser microphone is cylindrical, A case tube portion, a case inlet opening at one end of the case tube portion and a case deep portion at the other end, and the case deep portion is a bottom portion having an opening of the case tube portion; For the conductive case, Without masking the wall of the case tube, Of the conductive case The case From the entrance opening To the back of the case Blasting the conductive case The case The insulating layer provided at the back is removed and the conductive case The case Tube of Leave the insulating layer on the wall, The case Only the back A fixed electrode in contact with the back of the case; A step of enabling conduction. Acoustic transducer Is the ECM or electret condenser microphone It is.
[0013]
According to this configuration, by using blasting, the insulating layer at the back of the case can be removed at low cost, and the manufacturing cost of the acoustic transducer can be reduced. More specifically, according to the present invention, the cost of removing the insulating layer can be greatly reduced by applying blast, which has been used exclusively for deburring and the like, to remove the insulating layer of the conductive case. For example, as will be described in the following embodiments, when blasting is performed on a metal cylindrical case coated with a resin insulation layer, the resin insulation layer at the back of the case can be effectively removed. It is also possible to leave the insulating layer in the cylindrical portion without any special masking and remove the insulating layer in the back of the case. In this way, the present invention has an epoch-making effect that the removal of the insulating layer at the back of the case, which has been difficult in the past, can be realized at a lower cost than the conventional removal of the insulating layer near the entrance opening. It is done.
[0014]
Moreover, in the acoustic transducer manufacturing method of the present invention, the blast is a wet blast, and a treatment liquid is supplied to the conductive case. The case Drain from the opening in the back.
[0015]
With this configuration, it is possible to avoid the problem that the abrasive grains rebound when they collide with the back of the case, and the repelled abrasive grains collide with the wall surface of the case cylinder and damage the insulating layer on the wall surface. Also, the problem that the abrasive grains are scattered and remain in the case can be avoided.
[0016]
Another aspect of the present invention is an acoustic transducer manufacturing apparatus, a holding unit for holding a conductive case provided with an insulating layer for the acoustic transducer, and an inlet opening of the conductive case held by the holding unit. And a blast nozzle provided so as to blast from the back to the back.
[0017]
According to this configuration, as in the case of the above manufacturing method, by using blasting, the insulating layer at the back of the case can be removed at low cost, and the manufacturing cost of the acoustic transducer can be reduced. Even in this configuration, wet blasting is preferably applied, that is, the nozzle is preferably a nozzle that performs wet blasting.
[0018]
In the present invention, the holding means holds a plurality of conductive cases so that they are arranged in a two-dimensional direction, the nozzle has a slit for injecting a processing liquid, and the nozzle is angled with respect to the slit. Moving means for moving in the direction of
[0019]
With this configuration, the insulating layer removal of the conductive case for acoustic transducers such as a large number of conductive cases for ECM can be efficiently manufactured at low cost, and the cost reduction effect is further increased.
[0020]
Another aspect of the present invention is a method for manufacturing a case for an acoustic transducer, which is provided with an insulating layer. For electret condenser microphone Conductive case material A cylindrical conductive case having a case tube portion, a case entrance opening at one end of the case tube portion and a case back portion at the other end, and the case back portion opening the case tube portion The bottom of the conductive case For the process of molding into a shape and the molded member, Without masking the wall of the case tube, Of the conductive case The case From the entrance opening To the back of the case Blasting the conductive case The case Remove the inner insulating layer and remove the conductive case The case Tube of Leave the insulating layer on the wall, The case Only the back A fixed electrode in contact with the back of the case; Enabling conduction.
[0021]
Also with this configuration, by using blast, the insulating layer at the back of the case can be removed at low cost, and the manufacturing cost of the acoustic transducer can be reduced. Even in this configuration, wet blasting is preferably applied.
[0022]
Further, another aspect of the present invention is a method for manufacturing a case for an acoustic transducer, which includes a step of performing masking for exposing a portion to be conducted to a conductive case material provided with an insulating layer, and It includes a step of blasting the masked conductive case material and a step of forming the blasted conductive case material into a case shape.
[0023]
Also with this configuration, by using blast, the insulating layer of the case can be removed at low cost, and the manufacturing cost of the acoustic transducer can be reduced. Even in this configuration, wet blasting is preferably applied.
[0024]
Another aspect of the present invention is an electrical component manufacturing method, which includes an insulating layer. Has a tube and a back The conductive case is blasted from the entrance opening of the conductive case to remove the insulating layer provided at the back of the conductive case. And leaving the insulating layer on the cylindrical wall surface of the conductive case The back of the conductive case only Including the step of enabling conduction.
[0025]
According to this configuration, by using blast, the insulating layer of the case can be removed at a low cost, and the manufacturing cost of the electrical component can be reduced. As shown in this configuration, the present invention may be applied to electrical components other than the acoustic transducer. Even in this configuration, wet blasting is preferably applied.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0027]
1 and 2 show a preferred example of an acoustic transducer produced by the acoustic transducer manufacturing method of the present embodiment. FIG. 2 is a schematic diagram. In this embodiment, the acoustic transducer is an ECM, that is, the present invention is applied to an ECM manufacturing method.
[0028]
Referring to FIG. 1, the ECM 10 has a cylindrical conductive case 12. The conductive case 12 has a case tube portion 14, case entrance openings 16 and case back portions 18 at both ends thereof. The case back portion 18 is a cylindrical bottom portion and corresponds to the upper portion of the ECM 10.
[0029]
As shown in FIG. 1, the case back portion 18 has a relatively large opening 20. The fixed electrode 22 is inserted so as to be in contact with the case back portion 18, and the fixed electrode 22 constitutes the upper surface of the ECM 10 together with the case back portion 18. The fixed electrode 22 has a plurality of small holes (sound holes, for example, four, not shown) through which sound passes.
[0030]
In the conductive case 12, a spacer 24 and a diaphragm 26 are further arranged from the case back portion 18 toward the case entrance opening 16. The diaphragm 26 includes a diaphragm film 28 and a diaphragm ring 30 on the outer periphery thereof, and the diaphragm ring 30 supports the diaphragm film 28. A mounting substrate 32 is further accommodated in the conductive case 12. On the mounting substrate 32, the FET 34, the chip capacitor 36 and the chip resistor 38 are mounted so as to face the diaphragm 26, that is, so as to face the inside of the case. The conductive case 12 is caulked against the mounting board 32. A circular face cloth 40 is attached to the upper surface of the ECM 10.
[0031]
As shown in FIG. 2, the conductive case 12 is composed of a conductive member provided with an insulating layer (insulating film) 42. The conductive member is, for example, a metal plate, and the insulating layer is, for example, resin. In this embodiment mode, the conductive member is white and the insulating layer is polyimide. The thickness of polyimide is, for example, 7 micrometers. By adopting the insulating layer, a molded resin insulating structure is unnecessary. In addition, the fixed electrode 22 is a member having rigidity higher than that of the conductive case, and stainless steel is used in the present embodiment. Electric charges are held on the surface of the fixed electrode 22 facing the case.
[0032]
The ECM 10 in FIG. 1 is miniaturized by arranging the fixed electrode 22 on the upper surface. Furthermore, the adoption of the insulating layer ensures a large space despite its small size, so that the sensitivity can be improved.
[0033]
Furthermore, the fixed electrode 22 on the upper surface is made of stainless steel and has high rigidity. Thereby, the deformation | transformation of the fixed electrode 22 at the time of the caulking process of the electroconductive case 12 can be suppressed. This is advantageous for improving the sensitivity of the ECM 10. This advantage is considered to be remarkable as compared with a configuration in which the upper surface of the ECM 10 is integrated with the cylindrical portion, that is, a configuration in which the entire upper surface is white.
[0034]
Further, in the ECM 10 of FIGS. 1 and 2, charges are held on the surface of the fixed electrode 22 facing the inside of the case (the lower surface of the fixed electrode 22 in FIGS. 1 and 2). Therefore, the advantage that the electric charge is not easily lost by moisture and is strong against moisture is also obtained.
[0035]
In this regard, the conventional ECM is classified into a back electret type ECM and a front electret type ECM according to the position of the electric charge of the electret material when viewed from the direction in which sound comes. A typical back electret type is arranged in the order of a diaphragm and a fixed electrode, and there is a charge on the fixed electrode behind the diaphragm. On the other hand, the front electret side ECM is arranged in the order of the fixed electrode and the diaphragm, and the electric charge is positioned in front of the diaphragm.
[0036]
And with respect to moisture, the back electret type is generally more advantageous than the front electret type. The ECM 10 of FIG. 1 holds electric charges on the back side of the fixed electrode, which can be classified as a back electret type, and is relatively advantageous for moisture.
[0037]
Although the back electret type ECM and the front electret type ECM have been described in detail here, the present invention is not limited to such types of ECM, and the present invention can be applied to both types of ECMs. .
[0038]
As described above, the ECM 10 in FIG. 1 is advantageous in that it is small in size, has high sensitivity, and is resistant to moisture. For example, a high sensitivity of −50 dB to −20 dB is achieved at a diameter of 6 mm and a thickness of 1.0 mm or less, and a high sensitivity of −50 dB to −30 dB is achieved at a diameter of 4 mm and a thickness of 1.5 mm or less. A high sensitivity of −50 to −20 dB is achieved at a thickness of 1.5 mm. Further, the ECM 10 can greatly reduce the component mounting space. Because of such advantages, the ECM 10 is advantageously used for, for example, an ultra-thin mobile phone, a PDA, a video camera, and a hands-free phone capable of simultaneous multi-party calls.
[0039]
As described above, the ECM 10 of FIG. 1 is excellent. However, the case back portion 18 of the conductive case 12 needs to be electrically connected to the fixed electrode 22. The region to be conducted is a portion indicated by a symbol A in FIG. For this conduction, the insulating layer in the case back portion 18 must be removed.
[0040]
However, in the prior art, since the insulating layer is removed with a punch, a knife or the like, it is not easy to remove the insulating layer in the case back portion 18. Although removal by laser is also conceivable, there is a problem that the removed insulating layer remains, and there is a problem that the equipment investment is high, and this is reimbursed by cost.
[0041]
Since the ECM is severely limited in terms of cost, if the insulating layer at the back portion 18 of the case cannot be removed at low cost, practical use is practically difficult even if the ECM 10 in FIG. 1 is excellent.
[0042]
Therefore, the ECM manufacturing method of the present invention solves the above-described problems and enables the insulating layer of the case back portion 18 to be removed at low cost.
[0043]
Referring to FIG. 3, in the present embodiment, first, an insulating layer is formed on the conductive case material (S10). Then, a conductive case is formed from the conductive case material by press working such as drawing and punching (S12).
[0044]
Next, the insulating layer is removed from the back of the conductive case 12 (S14). At this time, wet blasting is applied as a feature of the present embodiment. After the insulating layer is removed, the ECM 10 is assembled (S16). Here, the conductive case 12 is arranged so that the inlet opening 16 faces upward, that is, upside down with respect to FIG. Then, the fixed electrode 22, the spacer 24, the diaphragm 26, and the mounting substrate 32 are inserted into the conductive case 12. Then, the conductive case 12 is caulked against the mounting substrate 32. Curling and annealing are performed. Further, the face cloth 40 is attached to the conductive case 12. The ECM 10 is completed through the measurement and inspection processes.
[0045]
FIG. 4 shows a preferred example of the insulating layer forming step of FIG. In the present embodiment, polyimide is baked at a predetermined position of the white plate 50. Here, a circle (dotted line) in FIG. 4 indicates a portion to be a conductive case. The width of the insulating layer 52 is set narrower than the diameter of this circle. Thereby, when the conductive case is press-formed later, a portion that is not covered with the insulating layer is left in the entrance opening of the conductive case. As is apparent from FIG. 4, the two places 180 degrees apart are not covered. These locations ensure electrical continuity when the conductive case and the substrate are caulked.
[0046]
FIG. 5 shows the insulating layer removal step of FIG. Note that, in the press work in the previous stage of this process, the conductive case material is formed into a cylindrical shape by drawing, and an opening 20 is formed in the case back portion 18 by punching.
[0047]
In FIG. 5, wet blasting is performed from the case inlet opening 16 as indicated by an arrow. By wet blasting, the insulating layer of the case back portion 18 is removed, and the case back portion 18 becomes conductive.
[0048]
Wet blasting is a technique for injecting a treatment liquid (slurry) such as water mixed with abrasive grains (abrasive) onto an object. Wet blasting itself is known as a technique used for purposes such as polishing, deburring, and surface modification (curing). In contrast, in the present embodiment, wet blasting is applied to the removal of the insulating layer of the ECM conductive case 12. By performing wet blasting, the processing liquid is sprayed on the case back portion 18, and a large number of abrasive grains collide with the case back portion 18, thereby removing the insulating layer.
[0049]
The sprayed processing liquid is discharged from the opening 20 in the case back portion 18. The processing liquid passes along a path from the case inlet opening 16 to the back to the opening 20. During this time, the insulating layer on the inner wall of the case tube portion 14 is not peeled off.
[0050]
The wet blasting conditions will be described. Blasting conditions are particle size, flow rate and processing time. The present embodiment is intended for a combination of a metal plate and a resin film (specifically, a combination of white and polyimide). The metal plate remains and the resin film may be removed. If this purpose is achieved, the grain size of the abrasive grains can be set to an arbitrary value within a wide range, for example, an arbitrary value between No. 80 and No. 2000. Depending on the particle size, the flow rate and processing time are also set. The finer the particle size, the smaller the surface roughness after processing, but the processing takes time. Therefore, the blasting condition may be set so that sufficient surface roughness that can ensure conduction is obtained and the processing time is within the required range. In the present embodiment, for example, No. 320 abrasive grains are employed.
[0051]
Here, in the present embodiment, the conductive member is a metal, and the insulating layer is a resin. More specifically, the conductive member is white and the insulating layer is polyimide. For such objects, wet blasting is very effective. That is, the insulating layer can be effectively removed leaving the conductive member. As described above, this embodiment finds that the treatment target is viewed from the material side and the wet layer blast removal capability is high, and pays attention to this, and adopts the wet blast.
[0052]
In addition, the present embodiment finds that the insulating layer removing ability of the wet blast is very high even when the object to be processed is viewed from the shape, and adopts the wet blast by paying attention to this.
[0053]
In other words, in the present embodiment, it is required to leave the insulating layer on the inner wall of the cylindrical portion and to remove the insulating layer at the back. This requirement is easily met with wet blasting. More specifically, when the wet blast processing liquid is sprayed from the case entrance opening toward the back of the case, the processing liquid advances along the wall surface and collides with the back of the case, so that the insulating layer at the back of the case is removed. However, the insulating layer on the wall remains. At this time, the masking of the wall portion may not be performed, which is particularly advantageous in terms of cost.
[0054]
Furthermore, in this Embodiment, the opening is provided in the case back part. The wet blast treatment liquid is discharged from the opening. According to the wet blasting, it is possible to effectively prevent the removed insulating layer from remaining as a foreign substance.
[0055]
Although the present embodiment has been described with wet blasting, the dry insulating layer can be easily removed in the same manner as wet blasting, and therefore, the present invention also includes dry blasting. That is, the blast of the present invention does not have to be limited to wet.
[0056]
In dry blasting, abrasive grains may rebound when they collide with the back of the case, and the repelled abrasive grains may collide with the wall surface of the case tube and damage the insulating layer on the wall surface. There is an advantage that it is difficult to occur.
[0057]
In dry blasting, abrasive grains may be scattered and remain in the case. However, wet blasting hardly causes such problems.
[0058]
As described above, this embodiment pays attention to blast that has been used for deburring in the past, and further finds that blast is suitable for removing the insulating layer at the back of the case. Yes. The reason why the blast is suitable for the application of the present embodiment is as described above from the material surface and the shape surface of the object. When blasting is employed, the insulating layer can be easily removed, and the cost is low because the processing is simple. Thus, according to the present embodiment, the insulating layer at the back of the case can be removed at low cost, and as a result, the ECM manufacturing cost can be reduced.
[0059]
Conventionally, even if the insulating layer at the case entrance opening can be removed with a punch or the like, it is difficult to remove the insulating layer at the back of the case, which is strict in terms of cost. However, the use of the blast of the present embodiment facilitates the removal of the insulating layer at the back of the case and dramatically reduces its cost. It is also particularly advantageous that no masking is required. Thus, according to the present embodiment, the insulating layer at the back of the case can be removed at a lower cost than the conventional insulating layer removal near the entrance. That is, in terms of cost, an epoch-making cost reduction effect that the insulating layer removal cost at the case entrance opening can be reversed is obtained.
[0060]
FIG. 6 shows an apparatus for wet blasting according to the present embodiment. The wet blasting device 60 includes a case holding unit 62, a nozzle 64, and a nozzle moving device 66. The case holding part 62 holds a conductive case. In the present embodiment, a plurality of conductive cases are held so as to be arranged in a two-dimensional direction. That is, the conductive case is held in each of a large number of small holes arranged vertically and horizontally.
[0061]
The case holding part 62 is made of a metal plate coated with urethane. The inner diameter of the small hole is slightly smaller than the outer diameter of the conductive case. The conductive case is press-fitted into the small hole. Thereby, the outer periphery of a conductive case adheres to the inner peripheral surface of a small hole using the elasticity of urethane.
[0062]
The nozzle 64 has an elongated shape, and the injection port is constituted by a slit 68. The treatment liquid is ejected from the slit 68 in a curtain shape. The nozzle 64 is disposed so that the slit 68 faces the case entrance opening of the conductive case, and thereby the processing liquid is ejected from the case entrance opening toward the back of the case. The nozzle 64 has a length corresponding to the width of the case holding portion 62 in the nozzle direction. The length of the slit 68 is set to such a length that the processing liquid can be sprayed to the case group arranged in the nozzle direction of the case holding portion 62.
[0063]
The nozzle moving device 66 moves the nozzle 64 in a direction that forms an angle with respect to the slit 68. In the present embodiment, the case holding portion 62 is, for example, a rectangle having a side of 500 mm, and the nozzle 64 moves in a direction perpendicular to the slit 68 so as to pass over all cases on the case holding portion. The nozzle moving device 66 includes a motor and a transmission mechanism (not shown).
[0064]
When using the apparatus of FIG. 6, first, the conductive case is held in each of the plurality of small holes of the case holding portion 62. Then, the processing liquid is supplied to the nozzle 64. The nozzle 64 ejects the processing liquid while moving above the case holding part 62. Thus, the processing liquid is sprayed from the case entrance opening toward the back of the case, and the insulating layer at the back of the case is removed.
[0065]
The blast processing apparatus of this embodiment has been described above. This device further enhances the advantage of adopting blasting to remove the insulating layer at the back of the conductive case. That is, since blasting is employed, the insulating layer can be removed simply by spraying the blasting treatment liquid. The spraying of the treatment liquid can be applied to many cases. If a large number of cases can be processed at once, it is more advantageous in terms of cost. The apparatus according to the present embodiment makes it possible to process such a large number of cases, thereby increasing the cost reduction effect.
[0066]
Thus, according to the present embodiment, since a plurality of conductive cases can be processed at a time, further cost reduction can be achieved.
[0067]
FIG. 7 shows another embodiment of the present invention. Wet blasting is also used in this embodiment. However, wet blasting is performed before press molding.
[0068]
As shown in FIG. 7, in the present embodiment, masking is applied to the case material 70 on which the resin insulating layer is formed. The masking area 72 and the exposed area 74 are set so that the portion to be conducted is exposed. That is, masking is performed so that the part which should become a case back part after press is exposed, and the part which should become a case cylinder wall after pressing is covered. The masking is made of a metal plate, for example. And wet blasting is given in the state where masking was given. A conductive case is then formed from the case material. Here, drawing and punching are performed.
[0069]
The present embodiment does not take advantage of the blasting that focuses on the shape of the object as compared with the previous embodiment. Therefore, masking is also necessary. Further, since the position of punching from the case material is limited by masking, a configuration such as a pilot hole for obtaining the accuracy of the punching position is required, and therefore, an extra material may be required. Although there is such a disadvantage, it is not necessary to set the case on the jig as shown in FIG. Further, at least from the viewpoint of the material, that is, a combination of a metal and a resin film, the advantage of adopting the blast of the present embodiment is utilized, and the cost reduction effect can be expected.
[0070]
The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. Of course, those skilled in the art can modify the above-described embodiments within the scope of the present invention. For example, the present invention can be applied to manufacture of acoustic transducers other than ECM, and can also be applied to manufacture of electrical components other than acoustic transducers.
[0071]
【The invention's effect】
As described above, the present invention is configured such that wet blasting is performed from the case entrance opening to the conductive case for the acoustic transducer, so that the insulating layer at the back of the case can be removed at a low cost. The acoustic transducer manufacturing method which has the outstanding effect that the manufacturing cost of a transducer can be reduced can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an ECM manufactured by the ECM manufacturing method of the present embodiment.
FIG. 2 is a schematic diagram of an ECM cross section manufactured by the ECM manufacturing method of the present embodiment.
FIG. 3 is a diagram showing an ECM manufacturing method according to an embodiment of the present invention.
FIG. 4 is a diagram showing an insulating layer forming process in the ECM manufacturing method of the present embodiment.
FIG. 5 is a diagram showing an insulating layer removal process at the back of the case in the ECM manufacturing method of the present embodiment;
FIG. 6 is a view showing an insulating layer removing apparatus constituting the ECM manufacturing apparatus of the present embodiment.
FIG. 7 is a diagram showing an insulating layer removal process according to another embodiment of the present invention.
[Explanation of symbols]
10 ECM
12 Conductive case
14 Case tube
16 Case entrance opening
18 Case back
22 Fixed electrode
24 Spacer
26 Diaphragm
28 Mounting board
60 Wet blasting equipment
62 Case holder
64 nozzles
66 Nozzle moving device

Claims (4)

An acoustic transducer manufacturing method including a step of removing an insulating layer provided in a conductive case for an electret condenser microphone that is an acoustic transducer,
The conductive case for the electret condenser microphone has a cylindrical shape, and includes a case tube portion, a case inlet opening at one end of the case tube portion, and a case back portion at the other end, A bottom portion having an opening of a case tube portion, and blasting from the case entrance opening of the conductive case toward the back of the case without masking the wall portion of the case tube portion with respect to the conductive case subjected to the provided in the case the inner part of the conductive casing of the insulating layer is removed and leaving the insulating layer of the wall of the casing cylindrical portion of said conductive case, said case back of the conductive case A method of manufacturing an acoustic transducer, comprising a step of allowing only a portion to conduct with a fixed electrode in contact with the back of the case . The acoustic transducer manufacturing method according to claim 1, wherein the blasting is wet blasting, and the processing liquid is discharged from an opening at the back of the case of the conductive case . A conductive case material for an electret condenser microphone provided with an insulating layer is a cylindrical conductive case, and includes a case tube portion, a case inlet opening at one end of the case tube portion, and a case back portion at the other end. And forming the back of the case into the shape of the conductive case, which is a bottom having an opening of the case tube part, and
The molded member is blasted from the case entrance opening of the conductive case to the back of the case without masking the wall portion of the case tube portion, and the case of the conductive case The insulating layer in the back part is removed and the insulating layer on the wall surface of the case tube part of the conductive case is left, and only the case back part of the conductive case can be electrically connected to the fixed electrode in contact with the case back part. And the process of
A method for producing a case for an acoustic transducer, comprising: The method for producing a case for an acoustic transducer according to claim 3, wherein the blasting is wet blasting, and the processing liquid is discharged from an opening at the back of the case of the conductive case .

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