KR20080110319A - Small-sized capacitor micro-phone - Google Patents

Abstract

A small-sized capacitor microphone improving reliability is provided to reduce an additional device cost and to omit an additional process for connection of devices by integrating an external RF(Radio Frequency) filter circuit and an amplification circuit on single wafer. A small-sized capacitor microphone(100) includes a sound part and a circuit part. The sound part has a structure where a vibrating film(170) and a back plate(190) are faced in between spacers. The circuit part amplifies a signal received from the sound part, and includes a ECM(Electret Condenser Microphone) chip(110) and a RF filter(120). The ECM chip includes an amplification circuit for amplifying a voltage generated by a variation of capacitance at the sound part. The RF filter prevents a high frequency external noise signal accompanied in an amplification process, and is mounted on a printed circuit board with the ECM chip to one package type.

Description

Miniature capacitor microphone {Small-sized capacitor micro-phone}

1 is a cutaway sectional view of a microphone according to the prior art;

2 is a basic configuration and circuit diagram showing the operating principle of the capacitor microphone.

3 is a PCB plan view of a microphone in which an ECM chip and an RF filter are mounted on a PCB metal connection pattern top surface.

4 and 5 are a plan view inside the package showing the integration of the ECM chip and the RF filter by separating the space in a single package according to an embodiment of the present invention.

6 is a circuit diagram illustrating a microphone according to the embodiment of FIG. 4.

FIG. 7 is a plan view showing the inside of a wafer showing an integrated ECM chip and an RF filter in a single chip according to another embodiment of the present invention. FIG.

Explanation of symbols on the main parts of the drawings

10: ECM chip 20: RF filter

30: single package 34: ground electrode (GND)

35: input electrode 36: first output electrode

37: second output electrode 40: lead frame

50: bonding wire 60: printed circuit board

The present invention provides a package for amplifying a chip for electret condenser microphone (ECM) (hereinafter referred to as an "ECM chip") incorporating an amplification circuit such as an FET and an RF filter for blocking external high frequency noise signals induced in an ultra-small microphone. Or a microcapacitor microphone circuit structure embodied as a chip shape.

In order to miniaturize and multi-function new mobile phones, it is necessary to reduce the size, size, and weight of components installed. In addition, as the video recording function of a mobile phone with a camera function is enhanced, interest in high quality microphones is increasing.

Accordingly, mobile communication device developers and manufacturers are currently working to add more components and make them cheaper, although space is limited, and the microphone is no exception.

That is, as the sensitivity decreases due to the miniaturization of the ECM, a high sensitivity ECM chip is required, and a thin film package is required due to the thinning of the applied product. In addition, according to the trend of multi-mode mobile phones, it is necessary to remove external high frequency noise that can be generated when various electric units are mounted inside the mobile phones.

1 is a cross-sectional view of a microphone according to the prior art, Figure 2 is a basic configuration and circuit diagram showing the operating principle of the capacitor microphone.

As shown, the microphone module configuration generally includes a diaphragm 170, an electrostatic film 180, an ECM chip 110, and an RF filter 120. The change in the capacitance between the diaphragm 170 and the back plate 190 and the electrostatic film 180 according to the voice signal is converted by the ECM chip 110 into an electrical signal, the ECM chip 110 is a simple RF filter 120 ) And is installed separately from a certain distance.

The transmitter of the mobile communication terminal emits a high frequency signal having a large instantaneous power ranging from several milliwatts (mW) to several watts (W) through an antenna, and the high frequency signal is supplied to the microphone 100 and an external sound pressure signal processing circuit. It is induced on the line between and applied to the ECM chip 110 inside or outside the microphone 100. At this time, when the magnitude of the high frequency signal applied to the ECM chip 110 is greater than or equal to a predetermined level, it operates nonlinearly to generate a noise component corresponding to the peak envelope, and the frequency of the peak envelope. Because the band usually overlaps with the sound pressure audio frequency, this signal is amplified with the sound pressure signal and enters the sound pressure signal processing circuit to become the microphone's loudest noise.

As a method for blocking the external high frequency noise signal and outputting only a desired audio frequency band, in the conventional microphone 100, the same printed circuit board as the ECM chip 110 (hereinafter referred to as "PCB", 160) The RF filter 120 circuit is formed by using one or more passive elements by spaced apart at regular intervals. Conventionally, the RF filter is formed by adding a capacitor, a resistor, a varistor, etc. to a circuit constituting the ECM chip. ) To each of the metal connection patterns.

That is, after mounting the ECM chip 110, there is a problem that the manufacturing process is very complicated by mounting the RF filter 120 circuit on the PCB 160 to be spaced a predetermined interval from the upper surface of the PCB 160. This is because the mounting space is very narrow, the difficulty was even greater.

The RF filter 120 removes high frequency noise by combining a capacitor and / or a resistor on the upper surface of the PCB. Eliminating high frequency noise in this way increases the size of the PCB used to manufacture the microphone for more than one circuit configuration, and increases the production cost due to the use of additional external devices such as chip capacitors, and microphones. Increasing the production cost caused by the increase of the process of connecting the external device to the device, and the reliability due to the poor contact that may occur due to the increase of the device to be attached to the outside.

In addition, there are problems such as reliability due to poor contact and noise removal limitation that may occur when the metal pattern is to be attached to the outside of the metal pattern.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. One package or one chip together with an ECM chip incorporating a circuit for amplifying an RF filter effective and reliable in blocking high frequency noise induced in a microphone The purpose is to miniaturize the overall microphone size by configuring a circuit pattern in the form to occupy an efficient space when mounting the single package or a single chip on the same PCB to significantly reduce the PCB space used for microphone manufacturing.

In addition, the present invention provides a layout for integrating an external RF filter with an ECM chip with a built-in amplification circuit, thereby reducing the cost of additional external components and omit additional processes required for connecting external components, thereby reducing production costs. There is another purpose to bring.

Still another object of the present invention is to eliminate the failure factors that may occur when the RF filter is attached to the upper surface of the same PCB with the ECM chip and to reduce external noise to improve the reliability of the product.

The structure of the present invention for achieving the above object, the micro-capacitor comprising a sound portion of the structure facing the vibrating membrane and the back plate with a spacer therebetween, and a circuit portion for receiving a signal from the sound portion to amplify it In the microphone, the circuit portion comprises an ECM chip including an amplifier circuit for amplifying the voltage generated by the capacitance change in the acoustic portion, and an RF filter for blocking the high frequency external noise signal accompanying the amplification process. The RF filter may be mounted in the form of a package on an upper surface of a printed circuit board together with the ECM chip.

Another configuration of the present invention for achieving the above object is composed of a sound unit having a structure in which a vibrating membrane and a back plate facing each other with a spacer therebetween, and a circuit unit for receiving a signal from the sound unit to amplify it In the micro-capacitor microphone, the circuit portion is composed of an amplifier circuit for amplifying the voltage generated by the capacitance change in the acoustic portion, and an RF filter circuit for blocking the high frequency external noise signal accompanying the amplification process, the amplification The circuit and the RF filter circuit are characterized by being composed of a single chip-shaped unit integrated on a single wafer.

At this time, the circuit unit, the first output terminal is connected to the lead frame is configured so that the signal amplified through the ECM chip passes through the RF filter circuit to block the high-frequency external noise signal, and opposes the output terminal And a second output terminal connected to another lead frame.

The second output terminal may be electrically connected to an external capacitor and / or an external simple circuit when the microphone performance of the condenser microphone is deteriorated to compensate for the microphone performance of the microphone. It is characterized in that to be kept in a state.

In addition, the second output terminal may be used as a ground electrode GND.

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

3 is a PCB plan view of a microphone in which an ECM chip and an RF filter are mounted on an upper surface of a PCB metal connection pattern. FIGS. 4 and 5 are embodiments of the present invention, in which an ECM chip and an RF filter are integrated by separating a space in a single package. Fig. 6 is a circuit diagram showing the inside of the package.

As shown, the bottom of the microphone is laid out by laying out the ECM chip 10 having the amplification circuit 10 and the RF filter 20 composed of a combination of resistors and / or capacitors in the form of a single package 30. By mounting on the metal connection pattern formed on the upper surface of the same PCB 60 of a predetermined thickness it is possible to minimize the required PCB area. In addition, there is an effect that can prevent interference and noise between the circuits constituting the ECM chip and the RF filter.

In this case, the amplifier circuit constituting the ECM chip 10 may be configured as a field effect transistor or an amplifier IC.

The ECM chip 10 includes at least three contact terminals corresponding to the electrode patterns formed on the PCB 60 to the outside of the side bottom of the chip 10 structure. That is, the input electrode 35, the output electrode 36, and the ground electrode 34 constituting the ECM chip 10 are connected to the metal electrode connection pattern formed on the PCB 60, thereby enabling electrical connection. .

At this time, the PCB 60 has a gold plated area on the outside, a copper plated area on the inside, and a rear part composed of a gold plated layer and an epoxy layer constituting a metal pattern area, an inner layer part which is an epoxy layer, and a pattern of the rear part. The ECM chip and the RF filter are laid out in a region corresponding to the gold plating layer, and the front portion is formed with a metal connection pattern layer formed of copper for electrical connection with each electrode constituting the circuit.

The RF filter 20 is composed of a combination of a plurality of resistors R and / or capacitors C connected to the first output terminal 36 and formed inside the filter.

The electrode connection between the circuit of the ECM chip 10 and the RF filter 20 in the single package is configured as shown in FIG. 4 or 5, wherein the circuit is shown in FIG. 6.

In this case, the circuit unit is configured such that a signal amplified by the ECM chip 10 passes through the RF filter 20 circuit so that a high frequency external noise signal can be cut off, and is connected to the lead frame 40. And a second output terminal 37 facing the first output terminal 36 and connected to another lead frame on the side of the package 30 structure.

In this case, when the microphone performance of the condenser microphone is degraded, the second output terminal 37 may be electrically connected to an external capacitor and / or an external simple circuit to compensate for the microphone performance of the microphone. It is preferable to configure it to remain in the idle state during operation.

In addition, according to the embodiment according to the present invention, if necessary, the second output terminal 37 may be used as the ground electrode GND instead of the second output terminal.

As shown in FIG. 4, the ground electrode 34 terminal is connected by the ECM chip 10, the terminals of the RF filter 20, and the bonding wire 50, and the input electrode 35 terminal is connected by the ECM chip 10. And the ECM chip 10 and the RF filter 20 by a bonding wire 50.

Alternatively, as shown in FIG. 5, the ECM chip 10 is connected to the input electrode 35, and one terminal of the ECM chip 10 is connected to the ground electrode 34, and the other terminal is connected to the second output. Can be connected to the terminal 37. One terminal of the RF filter 20 is connected to the ground electrode 34 and the other terminal is connected to the second output terminal 36. The electrical connection between the terminals is made by bonding wires. According to the package structure according to the layout, only two bonding wires 50 connected to the pattern in the package 30 in the ECM chip 10 or the RF filter 20 need to be used. Diversity can be secured.

The circuit configuration of the RF filter 20 is connected to the two capacitors in parallel, the resistor (so that the signal amplified in the ECM chip 10 can be output through the first output terminal 36 via the RF filter 20 ( R) is connected. However, the number and combinations of the capacitors C and resistors R may be variously configured.

By laying out the ECM chip 10 and the RF filter 20 in the form of a single package 30 as described above, it is possible to minimize the noise from the outside and to minimize the electrical interference between the circuit, the microphone PCB 60 The mounting work may be greatly simplified since the external terminals 34, 35, 36, and 37 of the chips 10 and 20 are connected to the metal connection pattern connection terminals on the upper surface.

As described above, when the structure of the single package 30 constituting the ECM chip 10 and the RF filter 20 circuit on the upper surface of the same PCB (60), it is slightly increased than the area occupied by the existing ECM chip 10 only However, it is smaller than the area when bonding the ECM chip 10 and the RF filter 20, respectively, there is an effect that the investment cost and labor costs of the production equipment required in the mounting process is reduced.

In addition, the RF filter 20 according to the present invention is formed in a single package 30 structure to minimize the size of the device and the number of parts used, and to form an equivalent circuit composed of resistors and capacitors to minimize residual resistance. This has the advantage of improving the audio frequency characteristics.

Hereinafter, another embodiment according to the present invention will be described. FIG. 7 is an internal plan view of a wafer illustrating the integration of an ECM chip and an RF filter on a single chip.

That is, as another embodiment, the circuit portion constituting the microphone, the ECM chip 10 composed of an amplifier circuit for amplifying the voltage generated by the capacitance change in the acoustic portion and the high frequency involved in the amplification process RF filter 20 for blocking an external noise signal, and the ECM chip 10 and the RF filter 20 circuit is formed by a lead frame 40 and a bonding wire 50 in which a plurality of external electrode terminals are formed. Disclosed is a structure in which a single chip-shaped unit integrated on a single wafer to enable electrical connection and chip mounting in a single chip structure on an upper surface of a printed circuit board 60 is disclosed.

In the above embodiment, the ground electrode terminal 34 and the input terminal 35 are connected to the ECM chip 10 by the bonding wire 50, and are connected to the RF filter 20 in contact with the ECM chip 10. An amplifier circuit and an RF filter circuit are formed on the lead frame 40 and connected through bonding wires 50 for electrical connection between the electrodes of the circuits and the electrodes formed on the lead frame 40.

According to the present embodiment, since the connection between the ground electrode 34 and the bonding wire 50 of the RF filter 20 is not necessary, the process operation is simpler, and the area previously used by two chips is used. Since it can be implemented in a single chip 300, there is an effect that can minimize the PCB area and reduce the size of the capacitor microphone.

Looking at the operation process briefly, the electrical signal of the acoustic module (ECM) is input to the ECM chip 10, which is a preamplifier, amplified and then transmitted to a signal processing circuit such as a mobile terminal in which a microphone is mounted. In this case, the signal amplified in the ECM chip 10 connected to the input electrode 35 and the ground electrode 34 terminal passes through the RF filter 20 which can be electrically connected to each other in a single chip, while generating high frequency external noise. The signal is filtered and then output to the first output electrode 36.

The RF filter 20 is configured by inserting and combining a resistor (R) and / or capacitor (C) that typically serves as a filter.

In this embodiment, a circuit is formed by integrating the ECM chip 10 and the RF filter 20 including the amplification circuit having the basic configuration on a single wafer, and the body of the single chip 300 having a predetermined size is the circuit. At least three or more connection terminals corresponding to each electrode pattern formed on the PCB are provided inside and outside the bottom of the chip 30 structure.

As shown in FIG. 7, the first output terminal 36 passes through the RF filter circuit 20 to remove external high frequency noise to enable output of a desired audio frequency band. Meanwhile, another second output terminal 37 is configured to face the first output terminal 36, so that when the microphone performance of the condenser microphone is deteriorated, it may be connected to an external capacitor or a simple circuit configured to supplement the performance. In this case, it is preferable to maintain the idle state during normal operation.

According to the present embodiment, the circuit unit is configured such that a signal amplified through the ECM chip 10 passes through the RF filter 20 circuit so that a high frequency external noise signal can be cut off and connected to a lead frame. It is preferable to comprise the output terminal 36 and the 2nd output terminal 37 which opposes the said 1st output terminal 36. FIG.

In addition, the second output terminal 37 may be used as the ground electrodes 34 and GND instead of the second output terminal.

Accordingly, the wafer 600 on which the single chip shape 300 is mounted is cut at a predetermined interval and then mounted on the upper surface of the PCB, thereby solving the problems of process complexity, connection failure, and noise increase according to the circuit implementation. . And, most of all, it is possible to realize a miniaturized capacitor microphone.

As mentioned above, although this invention was demonstrated by the limited embodiment and drawing, this invention is not limited by this, The person of ordinary skill in the art to which this invention belongs, Of course, various modifications and variations are possible within the scope of equivalents of the claims to be described.

As described above, according to the present invention, an effective and reliable RF filter in blocking high frequency noise induced in a micro microphone is implemented in one package form on the same printed circuit board surface along with an amplifying semiconductor chip. As a result, the chip size can be reduced by taking up an efficient space.

In addition, the present invention integrates an external RF filter circuit on a single wafer like an amplification circuit to realize a single chip shape, thereby reducing the cost of additional external devices and eliminating additional processes required for connecting external devices, thereby reducing production costs. There is an effect that can be brought.

Another effect of the present invention is to improve the reliability of the product by eliminating the contact failure factors that may occur when attaching the amplifier circuit and the RF filter circuit to the upper surface of the printed circuit board.

Claims (5)

In the micro-capacitor microphone comprising a sound portion having a structure in which a vibrating membrane and a back plate facing each other, and a circuit portion for receiving a signal from the sound portion and amplifying it, The circuit unit includes an ECM chip including an amplifier circuit for amplifying a voltage generated by the capacitance change in the acoustic unit, and an RF filter for blocking high frequency external noise signals accompanying the amplification process. The filter is a package for a micro-capacitor microphone, characterized in that mounting with the ECM chip in the form of a package on the upper surface of the printed circuit board. In the micro-capacitor microphone comprising a sound portion having a structure in which a vibrating membrane and a back plate facing each other, and a circuit portion for receiving a signal from the sound portion and amplifying it, The circuit part includes an amplifier circuit for amplifying a voltage generated by the capacitance change in the acoustic part and an RF filter circuit for cutting off a high frequency external noise signal accompanying the amplification process. A package for an ultra small capacitor microphone, comprising a single chip-shaped unit integrated on a single wafer. The method according to claim 1 or 2, The circuit unit may be configured to allow a signal amplified by the ECM chip to pass through the RF filter circuit so that a high frequency external noise signal may be cut off so as to be opposed to the first output terminal and the first output terminal. And a second output terminal connected to another lead frame. The method of claim 3, wherein The second output terminal may be electrically connected to an external capacitor and / or an external simple circuit when the microphone performance of the condenser microphone is deteriorated to compensate for the microphone performance of the microphone, and in an idle state when the microphone is normally operated. A package for microcapacitor microphones characterized in that they are retained. The method of claim 3, wherein And the second output terminal can be used as a ground electrode (GND).

Images