KR20050006969A - Backplate for electret condenser microphone, method of making the same and the microphone using the same - Google Patents

Abstract

PURPOSE: An electret condenser microphone, a backplate electrode for the same and a method for manufacturing the same are provided to reduce the manufacturing cost by reducing the number of elements in comparison with a conventional electret microphone. CONSTITUTION: An electret condenser microphone includes a case(21), a vibrational plate(22), an insulation ring(23), an unified backplate electrode(24) and a printed circuit board(PCB)(25). The peripheral portion of the ground surface is embossed and the protrusion portion is formed on the ground surface to function as a spacer. The space is formed between the ground surface and the vibrational film. The electret condenser microphone is characterized in that it connected to the PCB through the backplate electrode.

Description

Electret condenser microphone, bipolar plate for the same, and manufacturing method thereof {Backplate for electret condenser microphone, method of making the same and the microphone using the same}

The present invention relates to an electret condenser microphone, and more particularly, to an electret condenser microphone which can reduce manufacturing costs by integrating the parts of the electret condenser microphone, thereby reducing the number of parts and shortening the manufacturing process, and a bipolar plate for the same. It relates to a manufacturing method.

1 is a schematic diagram showing a conventional electret condenser microphone.

The conventional electret microphone 100 has a case 11 made of a cylindrical metal, a polar ring 12a made of a conductor, a vibration membrane 12b, a spacer 13, and a back plate as shown in FIG. 14) a ring-shaped first base made of an insulator (also called an insulating ring: 15), a second base made of a conductor (called a conductive ring: 16), and a PCB 17 on which circuit components are mounted and connecting terminals are formed. It is. Here, the diaphragm 12 may be integrally formed by attaching the vibrating membrane 12b to the polar ring 12a, and the back plate 14 may be formed on the bipolar plate 14b of the metal conductor by the bipolar surface 14a of the polymer film. ) Is attached to the electrode surface 14a to form an electret.

However, such a conventional electret condenser microphone has a problem in that the number of parts is complicated and the assembly process is complicated, thus increasing the manufacturing cost.

The present invention has been proposed to solve the above problems, and provides an integrated bipolar plate and a method of manufacturing the integrated bipolar plate, spacer, conductive ring function that can be applied to the existing electret condenser microphone integrally. There is a purpose.

Another object of the present invention is to produce an electret condenser microphone integrated plate and case, diaphragm, insulating ring, PCB that can perform the integrated double plate, spacer, conductive ring functions applied to the existing electret condenser microphone The present invention provides an electret condenser microphone that can reduce the number of parts and reduce the manufacturing cost by fabricating a combination of (PCB).

1 is a cross-sectional view showing a conventional electret condenser microphone,

2 is a cross-sectional view showing an electret condenser microphone according to the present invention;

3 is a cross-sectional view and a plan view of the integrated bipolar plate of FIG.

4 is an air flow diagram of an electret condenser microphone according to the present invention;

FIG. 5 is a process flowchart for explaining a manufacturing process of the integrated bipolar plate of FIG. 2;

Figure 6 is a view prepared for the assembly process of the microphone according to the present invention and the prior art.

* Explanation of symbols for main parts of the drawings

100: conventional electret microphone 11: case

11a: Sound hole 12: Diaphragm

12a: Polar ring 12b: Diaphragm

13: Spacer 14a: Double surface

14b: bipolar plate 15: insulation ring (base 1)

16: Conductive Ring (Base 2) 17: PCB (PCB)

200: microphone 21 according to the present invention: case

21a: Sound hole 22: Diaphragm

22a: Polar ring 22b: Diaphragm

23: Insulation ring (Base 1) 24: Integrated bipolar plate

24a: bipolar surface 24b: bipolar plate

24c: conductive ring portion 24d: spacer portion

24e: flange 24f: air passage

24i: Aeration 25: PCB

In order to achieve the above object, the integrated bipolar plate of the present invention is a bipolar plate made of a metal thin plate and a bipolar surface formed by thermally bonding a polymer film to the outside of the bipolar plate, and a cylindrical surface having an opposite side of the bottom surface opened. As the circumferential portion of the bottom surface is bent (embossing) to form a protrusion that functions as a spacer to form a gap between the bottom surface and the vibration membrane, it is possible to be in direct contact with the PCB through the bipolar plate It is done.

In addition, in order to achieve the above object, the method of manufacturing a bipolar plate of the present invention includes a process of forming a disc by thermally bonding a polymer film and a metal thin plate which are materials of the bipolar plate; A press working process of pressing the formed disc to form a cylindrical bipolar plate shape having one surface opened; And washing the tubular bipolar plate and injecting charge into the polymer film on the bottom to form an electret.

The press working process includes a deep drawing step of dipping the disc to make a barrel, a piercing step of forming a through hole in the bottom surface of the barrel, and an embossing step of forming a protrusion functioning as a spacer on the bottom surface; Bending the end of the barrel to the outside to form a flange, and forming a synchronous passage on the flange.

In addition, the microphone of the present invention, the sound hole is formed on the bottom surface in order to achieve another object as described above; A vibration plate electrically connected to the case and vibrating according to a sound pressure input through the sound hole; A bipolar plate made of a metal plate and a bipolar plane formed by thermally bonding a polymer film to an outer side of the bipolar plate, a cylindrical shape having an opposite side of the bottom surface opened, and having a flange formed at the end of the opening side. An integrated bipolar plate in which a circumferential portion of the protrusion is formed to have a protrusion functioning as a spacer between the diaphragm and the diaphragm; And a PCB supported by the flange and forming a space therebetween.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view of the microphone according to the present invention, wherein the microphone assembly 200 of the present invention includes a case 21, a diaphragm 22, an insulation ring 23, an integrated bipolar plate 24, and a PCB 25. do.

Referring to FIG. 2, the microphone 200 has a polar ring 22a and a vibrating membrane 22b disposed on the bottom surface of the case 21 in which one surface (called the bottom surface) is blocked and the other surface is opened. An integrated bipolar plate 24 is positioned inside the insulating ring 23 to support the pole plate 24 and to insulate the case 21. 24a) and the gold (Au) sputtered vibrating membrane 22b are disposed to face each other at a predetermined interval (24h1 in FIG. 3). At this time, a plurality of sound holes 21a are formed on the bottom surface of the case 21, and the vibration membrane 22b is electrically connected to the case 21 through the polar ring 22a, which is a conductive holder, and the vibration membrane 22b. ) And the polar ring 22a may be integrated to form one diaphragm 22.

The PCB 25 having the circuit components mounted thereon is placed on the flange 24e of the integrated bipolar plate to form an internal space formed by the PCB 25 and the integrated bipolar plate 24. After all parts are inserted, the upper part of the case 21 is bent and then contacted with the PCB 25 so that sound inside the microphone is not leaked to the outside in the curling process. At this time, the end of the case 21 bent through the instrument (not shown) in the curling process is pressed in the vertical direction, the external force through the instrument (not shown) is transmitted to the PC 25 and the PCB 25 can be deformed. have. By the way, the integrated bipolar plate 24 of the present invention forms a flange 24e to support the PCB 25, thereby preventing the PC 25 from being warped due to the external force generated in the curling process. It is possible to prevent the frequency characteristic defect caused by the sound of the sound leaked to the outside.

As shown in FIGS. 2 and 3, the integrated bipolar plate 24 according to the present invention has a bipolar face 24a formed by thermally bonding a polymer film to the outside of the bipolar plate 24b and the bipolar plate 24b made of a metal plate. The structure is a cylindrical shape (one side is called bottom) and the other side is open (other cylinders such as square cylinders are possible), and flange 24e is formed at the end of the opening side. The gap 24h1 is formed between the bottom surface and the vibrating membrane 22b by embossing the circumferential portion of the bottom surface so that the protrusion 24d functions as a spacer, and the flange 24e An air passage 24f for communicating air to both sides of the center of the air is formed. Here, the cylindrical portion 24c is referred to as a conductive ring portion because it functions to electrically connect the bipolar plate 24 to the PCB 25 like a conventional conductive ring, and the protrusion 24d is also referred to as a spacer portion.

In FIG. 3, (A) is a top view of the integrated bipolar plate 24 of this invention, (B) is sectional drawing. In FIG. 3, 24w represents the width of the air passage 24f formed in the flange 24e, 24h1 is the height of the bottom projection 24d, the distance between the bottom surface of the bipolar plate and the vibration membrane 22b, and 24h2 is the flange. The depth of the air passage 24f formed in 24e is shown. In addition, three through-holes 24i are formed on the bottom surface of the integrated bipolar plate 24 to communicate air.

The integrated bipolar plate 24 of the present invention having such a structure has a cylindrical shape and is directly connected to the circuit of the PCB 25 substrate through a bipolar plate 24b made of a conductive metal plate, so that the input terminal of the impedance IC element is provided. And electrically connected to the conventional electret condenser microphone (100 in FIG. 1) to perform the functions of the conductive ring (16 in FIG. 1) and the bipolar plate (14 in FIG. 1) integrally. 24d) is to integrate the diaphragm 22b and the bottom surface to maintain a constant interval, including the conventional spacer (13 in Figure 1) to perform a composite function.

Referring back to FIG. 2, the microphone 200 to which the integrated bipolar plate 24 according to the present invention is applied, the diaphragm 22b is electrically connected to the circuit of the PCB 25 through the polar ring 22a and the case 21. The integrated bipolar plate 24 is electrically connected directly to the circuit of the PCB 25, and an electret is formed on the bipolar surface 24a of the integrated bipolar plate 24.

Looking at the flow of air in the microphone 200 of the present invention, as shown in FIG. 4, the external air vibrates the vibrating membrane 22b through the sound hole 21a of the case, as well as the integrated bipolar plate 24. Into the inner space between the PCB 25 and the integrated bipolar plate 24 through the through-hole (24i) formed in the), it is communicated with the outside through the air passage (24f) formed in the flange (24e) of the integrated bipolar plate . That is, the air introduced through the sound hole 21a causes the vibration membrane 22b adhered to the diaphragm 22 to be shaken, and thus the trembling air flows into the internal space through the hole 24i of the bipolar plate. When the air introduced into the internal space does not flow to the outside, it is reflected again and transmitted to the vibrating membrane 22b, thereby inhibiting the vibration of the vibrating membrane 22b. If the vibration of the vibrating membrane 22b is not smooth, the sensitivity characteristic is impaired. can do. Therefore, an air passage 24f is formed in the flange 24e of the integrated bipolar plate according to the present invention to minimize the adverse effect of vibration of the vibration membrane due to the air reflected smoothly.

At this time, when the vibrating membrane 22b vibrates by the sound pressure introduced through the sound hole 21a, the distance between the vibrating membrane 22b and the integrated bipolar plate 24 is changed. When the interval is changed by the sound pressure, the capacitance formed by the vibrating membrane 22b and the integrated bipolar plate 24 is changed to obtain a change in the electrical signal (voltage) according to the sound wave. It is transferred to the JFET mounted in 25), amplified and transmitted to the outside through a connection terminal (not shown).

5 is a flowchart illustrating a manufacturing process of the integrated bipolar plate 24 according to the present invention.

Referring to FIG. 5, in the manufacturing process of the integrated bipolar plate 24, a process of forming a disc by thermally bonding the polymer film 402 and the metal thin plate 404, which are materials of the bipolar plate, is performed (S1). Press working process (S9) to form a cylindrical bipolar plate shape with one side opening by pressing, and washing the cylindrical bipolar plate and injecting electric charge into the polymer film on the bottom to form an electret (S7, S8) ) And the press working process (S9) to form a bipolar plate shape is a deep drawing of the disc (deep drawing) to create a cylinder drawing step (S2), a piercing step (S3) to form a hole in the bottom surface of the cylinder, the bottom surface An embossing step (S4) of forming a protrusion (24d) that functions as a spacer in the step, step of bending the end of the cylinder to the outside to form an outward flange (24e), the air passage (24f) to the outward flange (24e) Forming step (S6). Here, the deep drawing is a method of forming a seamless bottomed container on a flat plate. A cylindrical plate can be pressed by pressing a cylindrical punch onto a die with a hole. Piercing is a process of making holes of a desired shape in a material (thin plate) by means of a punching punching press die, and embossing is a type of stamping, which is a pair of upper and lower dies with unevenness opposite to each other in thin sheet metal. It is a processing method that prints various shapes.

Therefore, the conventional double plate (14 in FIG. 1) is punched out by pressing after the polymer film is thermally bonded to the metal plate, and a separate conductive ring 16 is electrically connected to the input terminal of the impedance IC element of the PCB. This was necessary, but spacers 13 were required to maintain a constant distance between the vibration membrane and the anode, but all these functions are integrally implemented in the integrated cathode plate 24 of the present invention.

On the other hand, the integrated bipolar plate 24 applied to the present invention improves reliability by replacing with a high hardness material to compensate for the characteristic instability caused by the deformation of the bottom surface of the bipolar plate 24b, drawing a material of high hardness By embossing the bottom flatness unstable element generated by the bottom surface center in the direction opposite to the vibrating membrane 22b, the bottom surface is reinforced, and the deformation of the bipolar plate 24b due to external force is minimized. That is, the double-sided polymer film 24a is uniformly thermally bonded to one surface of the metal plate 24b of a predetermined thickness. At this time, as the metal plate 24b, the elongation must be high, and the deep drawing must be possible. The hardness of the metal plate 24b should be easy and the heat adhesion with the polymer film 24a should be easy. The metal plate 24b to which the bipolar polymer film 24a is heat-bonded is pressed by a drawing mold to form the integrated bipolar plate 24 with the bipolar polymer film 24a outward, and the bottom surface of the vibrating membrane. (22b) By embossing larger than the inner diameter of the diaphragm 22 in the opposite direction, the bipolar and conductive diaphragms maintain a constant distance 24h1, and prevent the structural deformation of the bottom surface through the stage to prevent the integrated bipolar plate 24 due to external force. It prevents the reliability deterioration caused by the deformation of.

Figure 6 is a view of the assembly process of the microphone according to the present invention and the prior art.

Referring to FIG. 6, the conventional microphone assembly process includes a diaphragm 12, a spacer 13, an insulating ring 15, a bipolar plate 14, a conductive ring 16, and a PCB formed on a case 11. At least seven component assembly processes (601 to 607) inserting (17) are required.

In contrast, the microphone assembly process of the present invention is a five-part assembly process (701 to 705) for inserting the diaphragm 22, the insulation ring 23, the integrated bipolar plate 24, and the PCB 25 into the case 21. Suffice.

Therefore, the electret microphone 200 of the present invention can reduce the manufacturing cost by reducing the number of parts compared to the conventional electret microphone 100, it is possible to stabilize the yield by reducing the process defects by shortening the assembly process Automatic assembly is easier.

As described above, according to the present invention, compared to the conventional electret microphone, the number of parts can be reduced to reduce the manufacturing cost, and the yield can be stabilized by reducing the process defect due to the shortening of the assembly process, and the automatic assembly is more effective. It has an easy effect. In addition, the integrated bipolar plate of the present invention can improve the reliability by eliminating the characteristic unstable elements by reducing the deformable elements of the bipolar surface through structural reinforcement, and form a flange on the integrated bipolar plate to be deformed by the curing process. By preventing the PCB from bending by supporting the PCB with a metal, it is possible to prevent the frequency characteristic defect caused by the phenomenon that the sound inside the microphone leaks to the outside.

Claims (8)

A bipolar plate made of a metal thin plate and a bipolar plane formed by thermally bonding a polymer film to an outer side of the bipolar plate, and having a cylindrical shape with an opposite side of the bottom surface open, wherein the peripheral portion of the bottom surface is bent to form a spacer. The protrusion that functions is formed An integrated bipolar plate for an electret condenser microphone, characterized in that a gap is formed between the bottom surface and the vibrating membrane and directly contact the PCB through the bipolar plate. The flange of claim 1, wherein a flange for contacting and supporting the PCB is formed at an end of the opening side of the integrated bipolar plate. An integrated bipolar plate for an electret condenser microphone, characterized by being able to prevent warpage of the PCB substrate due to an external force by a curing process. According to claim 2, An air passage for communicating air to the flange is formed An integrated bipolar plate for electret condenser microphones, which allows air inside a microphone to flow smoothly to the outside. The method of claim 1, wherein the metal thin plate High elongation material is used to make the cylinder shape through deep drawing, relatively high hardness material is applied to minimize the bottom deformation of the bipolar plate, and thin material is applied to reduce the height of the product. However, the integrated bipolar plate for an electret condenser microphone, characterized in that the electrical conductivity and corrosion resistance without the need for a separate coating and made of a steel grade easy to heat-bond the polymer film for charge preservation. The integrated bipolar plate for an electret condenser microphone according to claim 1, wherein an electret is formed in the polymer film on the bottom surface, and a through hole is formed in the bottom surface. A case in which sound holes are formed on the bottom surface; A vibration plate electrically connected to the case and vibrating according to a sound pressure input through the sound hole; A bipolar plate made of a metal plate and a bipolar plane formed by thermally bonding a polymer film to an outer side of the bipolar plate, a cylindrical shape having an opposite side of the bottom surface opened, and having a flange formed at the end of the opening side. An integrated bipolar plate in which a circumferential portion of the protrusion is formed to have a protrusion functioning as a spacer between the diaphragm and the diaphragm; And And a printed circuit board (PCB) supported by the flange and forming a space therebetween. Forming a disc by thermally bonding the polymer film and the metal thin plate, which are materials of the bipolar plate; A press working process of pressing the formed disc to form a cylindrical bipolar plate shape having one surface opened; And And washing the tubular bipolar plate to form an electret by injecting electric charges into the polymer film of the bottom surface. The method of claim 7, wherein the press working process A deep drawing step of dipping the disc to make a barrel, a piercing step of forming a hole in the bottom surface of the barrel, an embossing step of forming a protrusion functioning as a spacer on the bottom surface, and an outer end of the barrel. Forming a flange by bending to form an air passage on the electret condenser microphone comprising the step of forming an air passage in the flange.