JP2001268695A - Electret capacitor microphone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ECM which uses a ceramic package. SOLUTION: This microphone is equipped with the ceramic package 7 which holds a back electrode 18 having an electret dielectric film 161 stuck on its top surface or a diaphragm ring 15 made of a metal material having a diaphragm film 16 stuck by mounting it on the upper-end surface; and a metal material film constituting an input terminal surface 73 is formed on the upper- end surface of the peripheral side wall 72 of the ceramic packet 7 and an input conduction film 74 is formed on the internal surface of the peripheral side wall 72 and the top surface of a bottom part 71 while extended from the input terminal surface 73. An IC bear chip including an impedance transducing circuit is fitted to the bottom part 71 of the ceramic package 7 and the input conduction film 74 is electrically connected to an input terminal 53' of the IC bare chip 50'; and a capsule 10 made of a metallic cylinder is provided and the ceramic package 7 is put in the capsule 10 to obtain the ECM.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electret condenser microphone, and more particularly to a member for mechanically holding a back electrode or a vibrating membrane ring to which a vibrating membrane is attached, and for electrically connecting various electric components including these. The present invention relates to an electret condenser microphone employing one ceramic package.

[0002]

2. Description of the Related Art A conventional example of an electret condenser microphone (hereinafter referred to as ECM) will be described with reference to FIG. The ECM shown in FIG. 8 is a back electret type ECM. In FIG. 8, a capsule 1 is made of a metal cylinder such as aluminum. One end surface of the capsule 1 is closed by the front plate 10. A center hole 1a, which is a sound hole, is formed at the center of the front plate 10. A vibrating membrane 7 attached to a vibrating membrane ring 8 made of a metal material is accommodated in the capsule 1, and the vibrating membrane ring 8 is in contact with a front plate 10. An electret dielectric film 5 is formed on the upper surface of the back electrode 4. The vibration film 7 is opposed to and positioned with the electret dielectric film 5 on the upper surface of the back electrode 4 via the insulating spacer 6. 3 is a resin holder. The resin holder 3 has a step formed on the entire periphery of the upper end portion, and the back electrode 4 is fitted and held therein. A back chamber 11 is formed at the center of the resin holder 3. An IC element 9 for impedance conversion is arranged in the back room 11. Reference numeral 2 denotes a printed wiring board.

In the above ECM, the back electrode 4 on which the electret dielectric film 5 is formed on the upper surface constitutes one electrode, and the vibrating film 7 constitutes the other electrode. The back electrode 4 as one electrode is connected to the input terminal of the impedance conversion IC element 9, and the other terminal is connected to the wiring of the printed wiring board 2. The vibrating membrane 7, which is the other electrode, is electrically connected to a ground terminal 52 via a vibrating membrane ring 8 made of a metal material, the capsule 1, and a conducting wire (not shown). Where E
In the CM, when a sound wave enters through the center hole 1a, the vibrating membrane 7 vibrates, and a change in electric capacity between the vibrating membrane 7 and the back electrode 4 corresponding to the vibration is output to the output 51 as an audio signal. be able to.

[0004]

In the above-mentioned conventional example, the resin holder 3 is used as a holder for fixing and holding the back electrode 4. The resin holder 3 forms a step portion for holding the back electrode 4 on the entire periphery of the upper end portion. However, since the external dimensions are minute, machining is not always easy, and the mechanical strength is increased to a certain degree. Since it is necessary to increase the weight, the ratio of the weight of the resin holder 3 itself to the total weight of the ECM becomes relatively large. The printed wiring board 2
An impedance conversion IC element 9 is arranged and electromechanically coupled to the impedance conversion IC element 9, and further, an output terminal, a ground terminal, and other electrical connection members are formed.

[0005] This ECM is, in terms of mechanical holding of the back electrode 4 and various electric connections including the back electrode 4, in the end,
Two electric components of the resin holder 3 and the printed wiring board 2 are used. If the number of parts increases even one, the number of assembling steps also increases, and the risk of forgetting to assemble the parts or errors in assembling or other defects increases. Therefore, it is desirable to reduce the number of parts as much as possible. The present invention solves the above-mentioned problem by employing one ceramic package as a member for mechanically holding a back electrode or a vibrating membrane ring to which a vibrating membrane is attached and for electrically connecting various electric components including the same. It provides a customized ECM.

[0006]

Means for Solving the Problems Claim 1: A back electrode 18 having an electret dielectric film 161 adhered to the upper surface or a vibrating film ring 15 made of a metal material having the vibrating film 16 adhered is mounted on the upper end surface. The ceramic package 7 to be held is provided, and a metal material film constituting the input terminal surface 73 is formed over the entire periphery on the upper end surface of the peripheral side wall 72 of the ceramic package 7, and the inner surface and the bottom 7 of the peripheral side wall 72 are formed.
1, an input conductive film 74 is formed by extending from the input terminal surface 73, an IC bare chip including an impedance conversion circuit is attached to the bottom portion 71 of the ceramic package 7, and the input conductive film 74 is attached to the IC bare chip 50 '. Is electrically connected to an input end 53 'of the capsule, and is provided with a capsule 10 made of a metal cylinder.
Thus, an electret condenser microphone housed in the housing was constructed.

In the electret condenser microphone according to the present invention, an electret dielectric film 161 is formed on the inner surface of the front plate 12 of the capsule 10, and a spacer 17 is provided in the capsule 10 via a spacer 17. An electret condenser microphone in which the vibrating membrane ring 15 was housed and then the ceramic package 7 was housed, and the capsule 10 was caulked to the ceramic package 7 was constructed. Further, in the electret condenser microphone according to claim 3:
The vibrating membrane ring 15 is housed in contact with the inner surface of the front plate 12 of the capsule 10 and then the electret dielectric film 161
, The back electrode 18 is accommodated through the spacer 17, the ceramic package 7 is accommodated, and the capsule 10 is caulked to the ceramic package 7 to form an electret condenser microphone.

Further, in the electret condenser microphone according to the present invention, the vibrating membrane ring 15 to which the vibrating membrane 16 on which the electret dielectric film 161 is formed is adhered to the lower surface is encapsulated in the capsule 10.
Of the front plate 12 in contact with the inner surface of the front plate 12, then the back electrode 18 is accommodated via the spacer 17, the ceramic package 7 is further accommodated, and the capsule 10 is caulked to the ceramic package 7 to form an electret condenser microphone. .

Here, in the electret condenser microphone according to any one of claims 1 to 4, the ceramic package 7 includes a bottom portion 71 and a peripheral side wall 72 integrated with and integrated with the bottom portion 71. Thus, an electret condenser microphone was constructed. Claim 6: In the electret condenser microphone according to claim 5, the bottom piece 71 'and the peripheral wall piece 72' are cut out from the ceramic green sheet 79, and the peripheral piece 72 'is attached to the bottom piece 71'.
Were stacked, integrated under pressure, and fired to form an electret condenser microphone.

[0010] Claim 7: Claims 2 to 4
In the electret condenser microphone described in any one of the above, an engagement step portion 721 for caulking a capsule to a lower end portion of the peripheral side wall 72 of the ceramic package 7.
Were formed facing each other to form an electret condenser microphone. Further, in the electret condenser microphone according to any one of claims 1 to 7, an IC bare chip 50 'is provided.
To an electret condenser microphone which is flip-chip bonded to a ceramic package 7.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the embodiments shown in the drawings. FIG. 1 illustrates the appearance of the capsule and the ceramic package of the embodiment. 1 (a) is a perspective view showing the inside of the capsule, FIG. 1 (b) is a view showing a sheet metal material of the capsule, and FIG. 1 (c) is a bottom view of the ECM assembled by caulking the capsule to a ceramic package. FIG. 1D is a perspective view showing the upper side of the assembled ECM.

The capsule 10 is formed by squeezing and cutting a raw material sheet metal of the capsule shown in FIG. 1 (b). Reference numeral 111 denotes a swaging piece described later.
161 is an electret dielectric film. The electret dielectric film 161 is formed by subjecting a tetrafluoroethylene-hexafluoropropylene copolymer (FEP), which has been previously applied to a raw material sheet metal and heat-sealed, to a charging treatment. An embodiment of the front electret type ECM will be described with reference to FIG.

In FIG. 2, a capsule 10 is formed by processing a metal plate such as aluminum or nickel silver into a rectangular cylinder. One end surface of the capsule 10 is the front plate 1
2 is closed. A slit 13 as a sound hole is formed in the center of the front plate 12. An electret dielectric film 161 is formed on the lower surface of the front plate 12. Electret dielectric film 161, a FEP film thickness of 13Myu ^t is applied to a lower surface of the front plate 12 330 ° C.
It is formed by performing a heat treatment for about 30 minutes before and after, or by laminating a film. A vibrating film 16 attached to a vibrating film ring 15 made of a metal material is accommodated in the capsule 10. In this case, the vibration film 16 is connected to the electret dielectric film 1 via an insulating spacer 17.
61 is positioned opposite to the lower surface. The vibration film 16 is 2
The film thickness of the mu ^t polypropylene sulfide 4 on one side of (PPS) or polyethylene terephthalate (PET)
It is formed by depositing a nickel vapor-deposited thin film having a thickness of 00A. If in mind that reflow soldering ECM, the vibration film 16 is a nickel thin film having a thickness 1～2Myu ^t is used.

7 shows a ceramic package according to the present invention. The ceramic package 7 is formed of a very low dish-shaped square cylinder made of ceramic. The ceramic package 7 includes a bottom 71 and a peripheral side wall 72 integrally formed with the bottom 71. The upper end face of the peripheral side wall 72 supports the diaphragm 15. At the center of the lower end of the peripheral side wall 72 of the ceramic package 7, two sets of engaging steps 721 are formed so as to face each other. At the open end of the side wall 11 of the rectangular capsule 10, four crimping pieces 111 are formed. An IC bare chip 5 is provided on the upper surface of the bottom portion 71 of the ceramic package 7.
0 ′ is positioned, die-bonded with a conductive thermosetting epoxy adhesive, and after wire bonding, the entire IC bare chip 50 ′ is completely sealed with a synthetic resin. The ECM is sealed by caulking the caulking piece 111 of the side wall 11 to the engaging step 721.

The electrical connection in the ceramic package will be described with reference to FIG. FIG. 3A is a perspective view illustrating the electrical connection between the ceramic package and the IC bare chip inside, and FIG. 3B is a perspective view illustrating the lower surface of the ceramic package. In FIG. 3, as described above, at the center of the outer lower end of the peripheral side wall 72 of the ceramic package 7, the engagement step 721 is formed on all four sides from the bottom surface of the bottom 71. On the upper end surface of the peripheral side wall 72, a metal material film constituting the input terminal surface 73 is formed over the entire circumference.
The input conductive film 74 is formed on the inner surface and the bottom 7 of the peripheral side wall 72.
A film is formed to extend from the input terminal surface 73 over the upper surface of the substrate 1. The input conductive film 74 is the IC bare chip 5
0 ′ is connected to an input terminal 53 ′ via a bonding wire 59. An output connection film 75 is formed on the upper surface of the bottom 71. Output end 5 of IC bare chip 50 '
1 'is connected to the output connection film 75 via the bonding wire 59. 76 is a ground connection coating.
The ground end 52 'of the IC bare chip 50' is connected to this ground connection film 76 via a bonding wire 59. A chip capacitor is connected between the output connection film 75 and the ground connection film 76. An output terminal 51 is formed at the center of the lower surface of the ceramic package 7. Although not explicitly shown in the figure, the output terminal 51 is electrically connected to the output connection coating 75 via a through hole penetrating the bottom 71. On the lower surface of the ceramic package 7, a ground terminal 52 is formed over the entire surface so as to surround the output terminal 51. The ground terminal 52 is further formed integrally and integrally with the engaging step 721 formed from the lower surface of the bottom 71 at the center of the lower end of the peripheral side wall 72. The ground connection film 76 is also electrically connected to the ground terminal 52 formed on the lower surface of the ceramic package 7 through a through hole penetrating the bottom 71, although not explicitly shown in the drawing.

The electrical connection of the ECM will be described with reference to FIG. 9 in addition to FIG. 2 and FIG. In the ECM, the vibrating membrane 16 forms one electrode, and the front plate 12 of the capsule 10 forms the other electrode. The vibrating membrane 16 which is one of the electrodes is a vibrating membrane ring 1 made of a metal material.
5. Input terminal surface 73, input conductive film 74, bonding wire 59 formed over the entire upper end surface of peripheral side wall 72
Is connected to the input end 53 'of the IC bare chip 50'. Front plate 12 of capsule 10, which is the other electrode
The IC is connected via the grounding terminal 52, the through-hole, the output connection film 76, and the bonding wire 59 formed on the engaging step 721 and the lower surface of the ceramic package 7.
It is electrically connected to the ground end 52 'of the bare chip 50'.

Here, in the ECM, when acoustic vibration enters the capsule 10 through the center hole 13, the vibrating membrane 16 vibrates by this, and the vibrating membrane 16 corresponding to this vibration and the front plate 12 of the capsule 10 Between the two ends of the resistor 55 as an audio signal. The manufacturing process of the ceramic package will be described with reference to FIGS. FIG. 4 is a view showing a ceramic green sheet, FIG. 4 (a) is a view showing a ceramic green sheet before cutting, and FIG. 4 (b) is a view showing a cut piece. 5A and 5B are views showing a piece constituting the ceramic package, FIG. 5A is a perspective view showing a bottom piece of the ceramic package, and FIG. 5B is a peripheral wall piece integrally formed at the bottom. FIG.

The ceramic green sheet 79 is 62 m long.
It has a shape dimension of about mx 100 mm in width. This one
An individual piece 7 ′ of about 4.0 mm square is cut out from the ceramic green sheets 79. This piece 7 'is a bottom piece 7
1 'and the peripheral wall piece 72'. Here, one ceramic green sheet 79 is prepared, and is used to cut out a bottom piece 71 ′ shown in FIG. 5A. Then, a through hole indicated by a small circle is also formed. Next, another one of the ceramic green sheets 79
Is prepared, and the peripheral wall piece 72 ′ shown in FIG. 5B is cut out using this. Prior to firing, the peripheral piece 72 ′ is overlapped with the bottom piece 71 ′ and pressurized to integrate them. When the peripheral piece 72 ′ is overlapped with the bottom piece 71 ′, the notch 721 ′ of the bottom piece 71 ′ and the lower surface of the peripheral piece 72 ′ form an engaging step 721. The integrated bottom piece 71 ′ and peripheral side piece 72 ′ are fired in a firing furnace to form the ceramic package 7. Output end 51 ', ground end 52', input end 5
3 ′, the conductive film 54 is formed after firing.

FIG. 6 is a diagram showing a cross section of an embodiment of the back electret type ECM. The same reference numerals are given to the members common to the above embodiments. In FIG.
The capsule 10 is formed of a metal cylinder such as aluminum nickel silver. One end surface of the capsule 10 is closed by the front plate 12. A center hole or a slit 13 which is a sound hole is formed in the center of the front plate 12. Capsule 10
A vibration film 16 attached to a vibration film ring 15 made of a metal material is accommodated therein, and the vibration film ring 15 is in contact with the front plate 12. The vibration film 16 is made of PPS or PE
It is formed by depositing a nickel deposited thin film having a thickness of 400 A on one side of T. If in mind that reflow soldering ECM, the vibration film 16 is a nickel thin film having a thickness 1～2Myu ^t is used. Back electrode 18 made of brass or brass
An electret dielectric film 161 is formed on the upper surface of the substrate. The electret dielectric film 161 has a thickness of 1
Depositing a FEP of 0~25μ ^t, or thickness 2~5μ ^t
Formed by evaporating silicon dioxide. The vibration film 16 is opposed to and positioned with the electret dielectric film 161 on the upper surface of the back pole 18 via the insulating spacer 17. The peripheral side wall 72 of the ceramic package 7 has a step portion 41 formed on the entire inner peripheral edge of the upper end portion, and the back electrode 18 is fitted and held therein. An input terminal surface 73 is formed on the upper surface of the step portion 41.

Referring to FIG. 9 in addition to FIG.
In this back electret type ECM, the back electrode 18 having the electret dielectric film 161 formed on the upper surface constitutes one electrode, and the vibration film 16 constitutes the other electrode. The back electrode 18, which is one of the electrodes, contacts the input terminal surface 73 formed on the upper surface of the step portion 41, and contacts the input terminal 53 ′ of the IC bare chip 50 ′ via the input conductive film 74 and the bonding wire 59. Connected. The vibrating membrane 16 serving as the other electrode includes a vibrating membrane ring 15 made of a metal material and the capsule 1.
0, it is electrically connected to the ground terminal 52 and the ground end 52 'formed on the caulking piece 111 and the engaging step 721. Here, in the ECM, when acoustic vibration enters through the center hole 13, the vibrating membrane 16 vibrates, and a change in electric capacity between the vibrating membrane 16 and the back electrode 18 corresponding to the vibration is used as an audio signal. The voltage can be output between both ends of the resistor 55.

FIG. 7 is a diagram showing a cross section of an embodiment of the foil electret type ECM. Members common to the embodiment of FIG. 6 are given the same reference numerals. In FIG. 7, the vibration film 16 has an electret dielectric film 1 on its lower surface.
61 is formed. The upper surface of the vibrating film 16 is attached to a vibrating film ring 15 made of a metal material, and is electrically connected to the back surface of the front plate 12 of the capsule 10 via the ring. The lower surface of the vibration film 16 is positioned and held on the upper surface of the back electrode 18 via an insulating spacer 17.

This foil electret type ECM is
The back electrode 18 constitutes one electrode, and the vibrating membrane 16 constitutes the other electrode. The back electrode 18, which is one of the electrodes, comes into contact with an input terminal surface 73 formed on the upper surface of the step portion 41,
I through the input conductive film 74 and the bonding wire 59
It is connected to the input end 53 'of the C bare chip 50'. The vibrating membrane 16, which is the other electrode, is electrically connected to the vibrating membrane ring 15 made of a metal material, the capsule 10, the caulking piece 111 and the ground terminal 52 and the ground end 52 ′ formed on the engaging step 721. Here, in the ECM, when acoustic vibration enters through the center hole 13, the vibrating membrane 16 vibrates, and a change in electric capacity between the vibrating membrane 16 and the back electrode 18 corresponding to the vibration is used as an audio signal. The voltage can be output between both ends of the resistor 55.

Here, the bare chip 50 ′ is flip-chip bonded to the ceramic package 7, so that the outer dimensions of the ECM can be reduced and the cost can be reduced. Referring to FIG. The bare chip 50 'has bumps 501 made of metal such as gold or solder as terminals on the lower surface. An input end 53 ′ is formed at the bottom 71 of the ceramic package 7. The connection between the bump 501 and the input terminal 53 'is performed by applying an anisotropic conductive film 61 between them. The bonding material for forming the anisotropic conductive film 61 is made of a thermosetting synthetic resin 611 in which fine gold balls 612 are dispersed. This bonding material is applied to a region of the bottom 71 of the ceramic package 7 where the bare chip 50 ′ is to be bonded,
The bare chip 50 ′ is placed in this area with the bump 501 and the input end 53 ′ facing each other, and the bare chip 50 ′ is pressed against the bottom 71 while heating. In this case, fine gold balls 612 dispersed in the thermosetting synthetic resin 611 between the bump 501 to which the pressing force is applied and the gate end 53 ′.
Are brought into cohesive contact while excluding the thermosetting synthetic resin. Eventually, the bump 501 and the gate end 53 ′ are electrically connected via the fine gold balls 612 in cohesive contact.

[0024]

As described above, the present invention provides one member as a member for performing the mechanical holding of the backing electrode or the vibrating membrane ring to which the vibrating membrane is attached and the electrical connection of various electric parts including these. By using the ceramic package described above, it is possible to provide an ECM that is easy to assemble with a reduced number of parts. That is, the ceramic package plays the role of the two components of the resin holder and the printed wiring board in the conventional example with one component, and greatly contributes to the reduction in the number of components and the number of assembly steps. And
The number of components is reduced, and the risk of forgetting to install components, erroneous installation, and other defects is reduced.

Further, the ceramic package 7 is composed of a bottom and a peripheral side wall integrated with and integrated with the bottom, a bottom piece and a peripheral side wall piece are cut out from the ceramic green sheet, and the two are superimposed and integrated under pressure. By firing, a large number of ceramic packages 7 can be manufactured efficiently. Furthermore, by forming the engaging step for caulking the capsule on the peripheral side wall of the ceramic package, the force for caulking the capsule is applied only to the peripheral side wall of the ceramic package only in its height direction, and is not applied to the bottom. Therefore, there is little possibility that the ceramic package will be damaged even if the thickness of the bottom portion is reduced. Therefore, the height of the ECM can be reduced by the amount by which the thickness of the bottom portion is reduced. Further, by flip-chip bonding the IC bare chip to the ceramic package 7, the height of the IC bare chip and its mounting can be reduced, which also contributes to reducing the height of the ECM.

[Brief description of the drawings]

FIG. 1 is a diagram showing an appearance of an embodiment.

FIG. 2 is a diagram showing a cross section of a front electret type ECM.

FIG. 3 is a perspective view illustrating a ceramic package.

FIG. 4 is a diagram illustrating a manufacturing process of the ceramic package.

FIG. 5 is a view showing a piece constituting a ceramic package.

FIG. 6 is a diagram showing a cross section of a back electret type ECM.

FIG. 7 is a diagram showing a cross section of a foil electret type ECM.

FIG. 8 is a diagram illustrating a conventional example.

FIG. 9 is a diagram illustrating electrical connections in the ECM.

FIG. 10 is a diagram illustrating flip chip bonding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Capsule 15 Vibration film ring 16 Vibration film 161 Electret dielectric film 18 Back electrode 50 'IC bare chip 53' Input terminal 7 Ceramic package 71 Bottom 72 Peripheral side wall 73 Input terminal surface 74 Input conductive film

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Shinichi Saeki 1-4-3 Kitakyuho-ji Temple, Yao-shi, Osaka F-Side Co., Ltd. F-term (reference) 5D021 CC03 CC11 CC19

Claims (8)

[Claims] 1. A ceramic package for mounting and holding a back electrode having an electret dielectric film attached to its upper surface or a vibrating film ring made of a metal material having a vibrating film attached to an upper end surface thereof. A metal material film constituting the input terminal surface is formed on the upper end surface of the peripheral side wall over the entire periphery, and is extended from the input terminal surface over the inner side surface of the peripheral side wall and the upper surface of the bottom to form an input conductive film. A film is formed, an IC bare chip including an impedance conversion circuit is attached to the bottom of the ceramic package, an input conductive film is electrically connected to an input end of the IC bare chip, and a capsule made of a metal cylinder is provided. An electret condenser microphone that is housed. 2. The electret condenser microphone according to claim 1, wherein an electret dielectric film is formed on an inner surface of a front plate of the capsule, and a vibrating membrane ring is accommodated in the capsule via a spacer,
An electret condenser microphone comprising a ceramic package housed therein and a capsule crimped to the ceramic package. 3. The electret condenser microphone according to claim 1, wherein the vibrating membrane ring is accommodated in contact with the inner surface of the front plate of the capsule, and then the back electrode is accommodated with the electret dielectric film on the upper side via the spacer. The electret condenser microphone further comprising a ceramic package, wherein the capsule is caulked to the ceramic package. 4. The electret condenser microphone according to claim 1, wherein a vibrating membrane ring on which a vibrating membrane on which an electret dielectric film is formed is adhered to a lower surface of the microphone in contact with an inner surface of a front plate of the capsule. An electret condenser microphone characterized in that the back electrode is accommodated via a spacer, the ceramic package is further accommodated, and the capsule is caulked to the ceramic package. 5. The electret condenser microphone according to claim 1, wherein the ceramic package comprises a bottom portion and a peripheral side wall integrated with the bottom portion. Condenser microphone. 6. The electret condenser microphone according to claim 5, wherein the bottom piece and the peripheral wall piece are cut out from the ceramic green sheet, the peripheral wall piece is overlapped with the bottom piece, press-integrated and fired. An electret condenser microphone characterized by being constituted. 7. The electret condenser microphone according to claim 2, wherein engaging step portions for caulking the capsule are formed at the lower end portion of the peripheral side wall of the ceramic package so as to face each other. An electret condenser microphone characterized in that: 8. The electret condenser microphone according to claim 1, wherein the IC bare chip is flip-chip bonded to the ceramic package.