WO2007018343A1

WO2007018343A1 - Silicon based condenser microphone and mounting method for the same

Info

Publication number: WO2007018343A1
Application number: PCT/KR2006/000386
Authority: WO
Inventors: Chung-Dam Song
Original assignee: Bse Co., Ltd
Priority date: 2005-08-10
Filing date: 2006-02-03
Publication date: 2007-02-15
Also published as: KR100675027B1; CN101010983A; CN101010983B

Abstract

Disclosed are a silicon based condenser microphone having a board which is formed with connection terminals on its part surface to be adapted to mount the silicon based condenser microphone to a main PCB of a product using a microphone package and a method for mounting the silicon based condenser microphone. There is provided a condenser microphone which is mounted on a main PCB having a hole into which the microphone is inserted and connecting pads. The condenser microphone comprises a metal case which is inserted into the hole of the main PCB; a board which is broader than the metal case and is mounted with a MEMS microphone chip and an ASIC chip having a electric pressure pump and a buffer IC and is formed with a connecting pattern for bonding with the metal case, the metal case being welded to the connecting pattern; and connecting terminals which are formed on a part side of the board which is mounted with the metal case to connect with the connecting pads of the main PCB. Since the case projected from the board of the microphone is inserted into the hole of the main PCB, the total height of the inventive assembly is lower than that of the conventional assembly, thereby efficiently using a part space within a product.

Description

SILICON BASED CONDENSER MICROPHONE AND MOUNTING METHOD FOR THE SAME

Technical Field

[1] The present invention relates to a condenser microphone, and, more particularly, to a silicon based condenser microphone having a board which is formed with connection terminals on its part surface to be adapted to mount the silicon based condenser microphone to a main PCB of a product using a microphone package and a method for mounting the silicon based condenser microphone. Background Art

[2] Generally, a condenser microphone which has been widely used in a mobile equipment or an audio equipment consists of a voltage bias element, a pair of a diaphragm and a back plate for forming a capacitor which is changed corresponding to a sound pressure, and a JFET for buffering an output signal. This typical condenser microphone consists of an assembly which is integrally assembled by inserting a vibration plate, a spacer ring, an insulating ring, a back plate, a conductive ring and a PCB into a case.

[3] Meanwhile, recently, a semiconductor fabricating technology using a micro- machining technology has been introduced for an integrated micro device. According to this technology which is called MEMS (Micro Electro Mechanical System), a micro-sensor, an actuator and an electro mechanical structure can be fabricated in a D unit using a micromachining technology which applies a semiconductor fabricating process, especially, an integrated circuit technology. A MEMS chip microphone manufactured by the micromachining technology has merits that miniaturization, high- performance, multifunction and integration can be obtained through the high precise micromachining technology and safety and reliability can be enhanced.

[4] Meanwhile, since the MEMS chip microphone manufactured by the micromachining technology should perform electrical driving and signal processing, it is required to package the microphone with another special purpose semiconductor chip device, that is, an ASIC (Application Specific Integrated Circuit).

[5] However, since a conventional silicon based condenser microphone package has a board which is formed with connecting terminals on the reverse side of a part side thereof, when mounting the condenser microphone package to a main PCB of a product (that is, a mobile phone and the like) using a microphone package, the condenser microphone is projected from the main PCB, whereby there have been problems that a space for mounting a part is inefficiently spent and the mounting operation is inconvenient. Disclosure of Invention

Technical Problem

[6] In order to solve the problems, an object of the present invention is to provide a silicon based condenser microphone having a board which is formed with connection terminals on its part side to be adapted to mount the silicon based condenser microphone to a main PCB of a product using a microphone package and a method for mounting the silicon based condenser microphone. Technical Solution

[7] According to one aspect of the present invention, there is provided a condenser microphone which is mounted on a main PCB having a hole into which the microphone is inserted and connecting pads. The condenser microphone comprises a metal case which is inserted into the hole of the main PCB; a board which is broader than the metal case and is mounted with a MEMS microphone chip and an ASIC chip having a electric pressure pump and a buffer IC and is formed with a connecting pattern for bonding with the metal case, the metal case being welded to the connecting pattern; and connecting terminals which are formed on a part side of the board which is mounted with the metal case to connect with the connecting pads of the main PCB.

[8] Further, according to another aspect of the present invention, there is provided a method for mounting a condenser microphone. The method comprises the steps of: preparing a main PCB which is formed with the hole for inserting the microphone and connecting pads for electrically connecting with the microphone; preparing the condenser microphone having a board which is formed with a hollow case projected from the center of a part side of the board and connecting terminals for connecting with the connecting pads on the part side thereof; and soldering the connecting pads of the main PCB and the connecting terminals of the microphone after inserting the case of the condenser microphone into the hole of the main PCB. Brief Description of the Drawings

[9] The above and other objects and features of the invention will become apparent from the following description of preferred embodiments taken in conjunction with the accompanying drawings, in which:

[10] Figs. IA and IB are perspective views of a first embodiment of a silicon based condenser microphone according to the present invention;

[11] Fig. 2 is a schematic view showing a mounting process of a silicon based condenser microphone according to the present invention;

[12] Fig. 3 is a sectional side view showing that a silicon based condenser microphone according to the present invention is mounted; [13] Fig. 4 is a view showing an example of a structure for a MEMS chip of a silicon based condenser microphone according to the present invention;

[14] Fig. 5 is a circuit diagram of a silicon based condenser microphone according to the present invention;

[15] Figs. 6A and 6B are perspective views of a second embodiment of a silicon based condenser microphone according to the present invention; and

[16] Fig. 7 is a sectional side view showing that a directional silicon based condenser microphone according to the present invention is mounted. Best Mode for Carrying Out the Invention

[17] Hereinafter, preferred embodiments of the present invention will be explained in detail with reference to the appended drawings.

[18]

[19] [Embodiment 1]

[20] Figs. IA and IB are perspective views of a first embodiment of a silicon based condenser microphone according to the present invention, Fig. 2 is a schematic view showing a mounting process of a silicon based condenser microphone according to the present invention, and Fig. 3 is a sectional side view showing that a silicon based condenser microphone according to the present invention is mounted.

[21] According to a silicon based condenser microphone 100, as shown in Fig. IA, a cylindrical metal case 110 is attached to a board 120 which is broader than the metal case 110, wherein the board is formed with connecting pads 122-1 to 122-4 1 which are connected with connecting pads 220-1 to 220-4 of a main PCB 210 of a product using the microphone on a part side 120a thereof. In the embodiment of the present invention, four connecting terminals are provided, but the number is merely an example. That is, two to eight connecting terminals may be provided. Further, if extending the connecting terminals 122-1 and 122-4 to a circumference of the PCB 120 or the reverse side of the part side, a heat transfer of an electric iron is improved, whereby a rework operation can be more convenient.

[22] The main PCB 210 where the silicon based condenser microphone 100 is mounted, as shown in Fig. IB, is formed with a circular inserting hole 210a for mounting the case 110 of the silicon based condenser microphone and the connecting pads 220-1 to 220-4 corresponding to the connecting terminals 122-1 to 122-4 which is formed on the board 120 of the microphone.

[23] Then, an example for mounting the silicon based condenser microphone 100 on the main PCB 120 will be explained with reference to Fig. 2. Referring to Fig. 2, the part side 120a of the microphone board which is formed with the connecting terminals 122-1 to 122-4 and is provided with the metal case 110 faces the main PCB 210 and then the case 110 of the microphone is inserted into the hole 210a of the main PCB 210. Then, the connecting pads 220-1 to 220-4 are connected with the connecting pads 122-1 to 122-4 by a soldering operation.

[24] As such, according to a structure of Fig. 3 that the silicon based condenser microphone 100 is mounted on the main PCB 120, the metal case 110 projected from the central portion of the part side 120a of the board is inserted the inserting hole 210a of the main PCB 220, and the connecting pads 220 of the main PCB and the connecting terminals 122 of the microphone are connected by a solder 230.

[25] Thus, according to a mounting method of the present invention, since the case 110 projected from the board of the microphone is inserted into the inserting hole 210a of the main PCB 210, a total height t of an assembly according to the present invention is lower than that of an assembly assembled when the conventional microphone having the board which is formed with the connecting terminals on the reverse side of the part side thereof, thereby efficiently saving a space for mounting a part of the product.

[26] Referring again to Fig. 3, the board 120 is mounted with a MEMS chip 10 and an

ASIC chip 20 within the metal case of the silicon based condenser microphone 100 and is formed with a circular connecting pattern 121 on its portion which contacts the metal case 110. Meanwhile, although there is not shown in the drawing, if necessary, the board may be mounted with a capacity or a resistor for shielding electromagnetic waves or ESD. Here, the board 120 may be selected among a PCB, a ceramic board, a FPCB, a metal PCB and the like. The metal case 110 is formed with a sound hole 112 for collecting a sound. The metal case 110 is made of any one selected from the group of brass, copper, stainless steel, aluminum, nickel alloy and the like. Further, the metal case 110 may be plated with Au or Ag.

[27] Further, as shown in Fig. 3, if extending the connecting terminal 122 through the circumferential part to the reverse side of the part side, a heat transfer of an electric iron is improved, whereby a rework operation can be more easily performed. Meanwhile, although there is not shown in the drawing, the connecting terminal 122 may be extended up to the circumferential part of the board.

[28] Further, the MEMS chip 10, as shown in Fig. 4, has a structure that a back plate 13 is formed on a silicon wafer 14 by using a MEMS technology and then a spacer 12 is interposed between a vibration membrane 11 and the back plate 13. Since this fabricating technology of the MEMS chip 10 has been known, the further explanation will be omitted.

[29] The ASIC chip 20 which is connected with the MEMS chip 10 to process electrical signals, as shown in Fig. 5, consists of an electric pressure pump 22 for supplying an electric pressure to allow the MEMS chip 10 to be operated as a condenser microphone, and a buffer IC 24 for amplifying an electric sound signal sensed through the MEMS chip 10 or performing impendence matching of the sensed electric sound signal, thereby supplying the processed signal through the connecting terminal to the outside. Here, the electric pressure pump 22 may be a DC-DC converter, and the buffer IC 24 may use an analogue amplifier or an ADC. Referring to Fig. 5, a condenser symbol "CO" indicates an electrical equilibrium circuit for the MEMS chip 10. Here, the MEMS microphone package 100 is connected through three connecting terminals (Vdd, GND, Output) to the external device.

[30]

[31] [Embodiment 2]

[32] Figs. 6A and 6B are perspective views of a second embodiment according to the present invention, wherein Fig. 6A is a view showing a silicon based condenser microphone 100 having a rectangular parallelepiped shaped metal case, and Fig. 6B is a view showing a main PCB 210 of a product for mounting a silicon based condenser microphone 100 having the rectangular parallelepiped shaped metal case.

[33] According to the silicon based condenser microphone 100' of the second embodiment of the present invention, a rectangular parallelepiped shaped metal case 110' is attached to a board 120, wherein the board is formed with connecting pads 122 which are connected with connecting pads 220 of a main PCB of a product using the microphone on a part side 120a thereof.

[34] The main PCB 210 of the product where the silicon based condenser microphone

100' is mounted, as shown in Fig. 6B, is formed with a rectangular inserting hole 210b for mounting the case 110' of the silicon based condenser microphone and the connecting pads 220 corresponding to the connecting terminals 122 which are formed on the board 120 of the microphone.

[35] Then, a process for mounting the silicon based condenser microphone 100 on the main PCB 120 will be explained with reference to Figs. 6 A and 6B. The mounting process includes the steps of preparing the main PCB 210 which is formed with the hole 210b for inserting the microphone and the connecting pads 220 for electrically connecting with the microphone, preparing the condenser microphone 100 having the board which is formed with the rectangular parallelepiped metal case projected from the center of the part side 120a of the board and the connecting terminals 122 for connecting with the connecting pads 220 on the part side thereof, and soldering the connecting pads 220 of the main PCB and the connecting terminals 122 of the microphone after inserting the case 110' of the condenser microphone into the hole 210b of the main PCB. This process is substantially identical to the mounting process of the first embodiment except that the case has the rectangular parallelepiped shape.

[36] Fig. 7 is a sectional side view showing that a directional silicon based condenser microphone according to the present invention is mounted. [37] According to the silicon based condenser microphone shown in Fig. 7, the metal case 110/110' projected from the board is inserted into the hole 210a/210b of the main PCB 210, and the connecting terminals 122 of the part side 120a of the microphone board are connected with the connecting pads 220 of the main PCB by a solder 230.

[38] Here, according to the directional silicon based condenser microphone of the present invention, provided is a structure having a directivity by forming a front sound inlet hole 110a on a portion of the metal case 110/110 which corresponds to a portion where the MEMS chip 10 is positioned in the first embodiment and the second embodiment, forming a rear sound inlet hole 120b which is formed on a portion of the PCB where the MEMS chip 10 is mounted, and adding a sound resistor 140 to the inside and outside of the front sound inlet hole 110a or the inside and outside of the rear sound inlet hole 120b.

[39] According to this structure shown in Fig. 7, sound collected through the front sound inlet hole 110a or the rear sound inlet hole 120b passes through the sound resistor 140 and then its phase is changed, thereby obtaining directivity. According to the second embodiment of the present invention, the sound resistor 140 is positioned at the inside of the front sound inlet hole 110a, but it may be positioned at the outside of the front sound inlet hole 110a or the inside or the outside of the rear sound inlet hole 120b. Industrial Applicability

[40] From the foregoing, the silicon based condenser microphone has the board which is formed with the connecting terminals on the part side thereof, and the main PCB is formed with a hole for mounting the microphone. Thus, according to the silicon based condenser microphone which is mounted on the main PCB of the present invention, since the case projected from the board of the microphone is inserted into the hole of the main PCB, the total height of the inventive assembly is lower than that of the conventional assembly, thereby efficiently using a part space within the product.

[41] While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the present invention is not limited to the disclosed embodiment, but, on the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

[1] A silicon based condenser microphone which is mounted on a main PCB having a hole into which the microphone is inserted and connecting pads, the condenser microphone comprising: a metal case which is inserted into the hole of the main PCB; a board which is broader than the metal case and is mounted with a MEMS microphone chip and an ASIC chip having a electric pressure pump and a buffer

IC and is formed with a connecting pattern for bonding with the metal case, the metal case being welded to the connecting pattern; and connecting terminals which are formed on a part side of the board which is mounted with the metal case to connect with the connecting pads of the main

PCB. [2] The silicon based condenser microphone according to claim 1, wherein the metal case has any one of a cylindrical shape and a rectangular parallelepiped shape. [3] The silicon based condenser microphone according to claim 2, wherein an opened end of the metal case has any one of a straight line shape and a skirt shape which is formed by bending outward. [4] The silicon based condenser microphone according to claim 1, wherein the board is any one selected from the group of a PCB, a ceramic board, a FPCB and a metal PCB. [5] The silicon based condenser microphone according to claim 1, wherein the metal case is made of any one selected from the group of brass, aluminum and nickel alloy. [6] The silicon based condenser microphone according to claim 1, wherein the connecting terminals are formed with two to eight connecting terminals. [7] The silicon based condenser microphone according to claim 1, wherein the board is formed with a rear sound inlet hole for collecting a rear sound, whereby the microphone has directivity. [8] A method for mounting a silicon based condenser microphone, the method comprising the steps of: preparing a main PCB which is formed with the hole for inserting the microphone and connecting pads for electrically connecting with the microphone; preparing the condenser microphone having a board which is formed with a hollow case projected from the center of a part side of the board and connecting terminals for connecting with the connecting pads on the part side thereof; and soldering the connecting pads of the main PCB and the connecting terminals of the microphone after inserting the case of the condenser microphone into the hole of the main PCB.