KR20080005801A - Packging structure of mems microphone - Google Patents

Abstract

A packaging structure of MEMS(Micro Electro Mechanical System) microphone is provided to simplify a manufacturing process for MEMS microphone by simply connecting PCB(Printed Circuit Board) and external electrodes with conductive spring. A packaging structure of MEMS(Micro Electro Mechanical System) microphone includes a first PCB(100a), a MEMS die(150), a case(200), a second PCB(100b), and a plurality of conductive springs(500). The first PCB has a sound hole(120b) formed therethrough. The MEMS die is mounted on the first PCB facing the sound hole and converts sound signals to electric signals. The case has a first sound hole(120a) formed on one side thereof, has an opening on the other side, and receives the first PCB allowing the first sound hole and the sound hole to face each other. The second PCB has a plurality of electrodes(220) passing therethrough and seals inside the case. The plurality of conductive springs are inserted and fixed between the first and second PCBs for transmitting electric signals from the MEMS die to the electrodes.

Description

MEMS microphone packaging structure {PACKGING STRUCTURE OF MEMS MICROPHONE}

1 is a perspective view of a MEMS microphone packaged according to a first embodiment of the present invention.

2 is an exploded perspective view of a MEMS microphone according to the first embodiment of the present invention.

3 is a cross-sectional view of the MEMS microphone of FIG. 1 taken along line A-A '.

4 to 7 are exemplary views showing the shape of various conductive springs according to an embodiment of the present invention.

8 is a cross-sectional view of a MEMS microphone packaged using a conductive spring according to the first embodiment of the present invention.

9 is an exploded perspective view of a MEMS microphone packaging structure according to a second embodiment of the present invention.

      <Description of Symbols for Main Parts of Drawings>

100a: 1st PCB 100b: 2nd PCB

120a: first sound hole 120b: second sound hole

150: Messdie 200, 2000: Case

220, 2200: electrode 250: curling portion

300: hermetic layer 500, 5000: conductive spring

510: spring support 530: conductive rod

550: coil spring

The present invention relates to a MEMS microphone packaging structure, and more particularly, to a MEMS microphone packaging structure in which a PCB and an electrode are energized using a conductive spring to transmit an electrical signal output from an MEMS die of a PCB having a sound hole to an external device. .

A microphone is a device that converts external voice signals into electrical signals.It is embedded in medical devices such as mobile phones, moving picture experts group layer 3 (MP3), telephones, medical devices such as hearing aids, or miniaturized multifunctional smart sensors, or small precision devices. Mainly used. Since these compact microphones are generally manufactured through mechanical processing, they have physical limitations that are difficult to miniaturize to large mm and small micron units. However, as the miniaturization of acoustic devices or information communication devices in which the microphones are mounted is accelerated, the miniaturization of the microphones is increasingly required.

In order to overcome the limitations of miniaturization and mass production of microphones, the development of MEMS microphones, which form a capacitive structure directly using semiconductor manufacturing technology on silicon wafers, has been recently activated. . MEMS microphones, also called silicon microphones, are highly regarded for their performance and production efficiency because they can be miniaturized and the separate production process between parts can be combined.

MEMS microphones are manufactured by applying semiconductor processing technology using Surface Mount Technology (SMT) and Micro Electro Mechanical Systems (hereinafter referred to as "MEMS") technology.

Surface mounting technology prints solder paste such as lead on a printed circuit board (PCB), and mounts various surface mount devices (SMDs) on it. After attaching by using, it refers to the technology of joining the lead between the PCB and the electronic component by passing through the reflow machine (Reflow Machine). Microphones can use these surface-mount technologies to simplify or miniaturize microphone manufacturing by mounting electronic circuit components such as MEMS dies, amplifiers, and filters on a PCB.

In addition, MEMS technology uses silicon processing, especially micromachining technology applied to integrated circuit technology, for bulk processing of silicon wafers, structural layer processing, surface microfabrication, thin film processing, homogeneous or heterogeneous substrate bonding, 3 By performing the dimensional structure molding or the like, it is possible to manufacture a micro sensor, an actuator and an electromechanical structure in the unit of μm. Micromachines manufactured by micromachining techniques can realize sizes of mm or less and precision of μm or less.

SMT and MEMS technology enabled the production of micro-electromechanical systems dies with transducers, or diaphragms, which are the key components of ultra-small and high-performance MEMS microphones. The PCB fabrication by Messdie and SMT technology can greatly increase productivity by miniaturizing the microphone and simplifying various processes in packaging MEMS microphones.

In a conventional MEMS microphone, a PCB in which circuit elements such as MEMS Dai, an application specific integrated circuit (ASIC), an amplifier, and a filter for converting an external sound into an electric signal are mounted is externally connected to the electric signal through a separate electrode. To the device.

Meanwhile, in transmitting electric signals output from a PCB to an external electrode, a conventional MEMS microphone forms an electrode for applying an electric signal to an external device on a case or another PCB, and a separate conductive component for conducting electricity between the MEMS die and the electrodes. This can be done by mounting the structure or by applying structural modifications inside the case. This means the addition of the MEMS microphone manufacturing process, which leads to a decrease in the production yield of the microphone, whereas the manufacturing cost increases.

In addition, there is a problem that the operation of the MEMS microphone due to a poor contact between the PCB and the internal conductive path formed inside the case in the process of combining the case and the PCB.

An object of the present invention is to solve the above problems, to provide a MEMS microphone packaging structure for energizing the PCB and the electrode using a conductive spring to transmit the electrical signal output from the MEMS die mounted on the PCB to an external device. There is.

In addition, another object of the present invention is to provide a MEMS microphone packaging structure that can simplify the MEMS microphone production process for forming a separate internal conductive path by connecting a PCB mounted with a MEMS die and an external electrode with a conductive material spring. have.

In addition, another object of the present invention is a MEMS microphone capable of energizing the first PCB having the second sound hole and the second PCB having the electrode corresponding to the first sound hole formed in the case by using a spring and a spring support of a conductive material. To provide a packaging structure.

Finally, another object of the present invention is to use SMT, conductive epoxy sealing by using a conductive material spring to energize the first PCB with the second sound hole and the second PCB with the electrode corresponding to the first sound hole formed in the case. In addition, the present invention provides a MEMS microphone packaging structure capable of securing electrical coupling between a first PCB and a second PCB by applying resistance and laser welding.

In order to achieve the above object, the MEMS microphone packaging structure according to the first embodiment of the present invention, the first printed circuit board through which the sound hole is formed through the upper and lower surfaces; A mes die mounted on the first printed circuit board in correspondence with the sound hole position and converting a voice signal into an electric signal; A case in which a first sound hole is formed on one surface and a cylindrical shape in which the other surface is opened, and accommodates the first printed circuit board so that the first sound hole and the sound hole face each other; A second printed circuit board having a plurality of electrodes penetrating an upper surface and a lower surface thereof, the second printed circuit board being coupled to the opening surface of the case and sealing the inside of the case; And a plurality of conductive springs inserted and fixed between the first printed circuit board and the second printed circuit board so as to transfer the electrical signal output from the MEMS die to the electrodes.

MEMS microphone packaging structure according to a second embodiment of the present invention, a plurality of electrodes formed on the outside of one surface and the other side of the cylindrical case opening; A printed circuit board covering the opening surface of the case to seal the internal space of the case and having a sound hole penetrated therethrough; A mes die mounted on the printed circuit board corresponding to the sound hole position and converting a voice signal into an electric signal; And a plurality of conductive springs inserted and fixed between the printed circuit board and the case to transfer the electrical signal output from the MEMS die to the electrodes.

MEMS microphone packaging structure according to the first embodiment of the present invention, the second sound hole is formed corresponding to the first sound hole formed in the case and the electrical signal converted from the MEMS die mounted corresponding to the second sound hole In order to amplify and filter and transfer the filter to an external device, a second PCB is provided that seals the case and includes a plurality of electrodes for transmitting the electrical signal to the external device.

Meanwhile, in transferring the electrical signal converted from the MEMS die of the first PCB to the electrode of the second PCB, SMT, conductive epoxy sealing, resistance, and laser welding are applied by using a spring made of a conductive material so that the first and second PCBs can be used. The electrical connection of the can be secured. In addition, in order to facilitate fixing of the conductive spring, a spring support may be further provided on the first PCB and the second PCB conductive spring connecting portions to prevent the spring from being separated during packaging of the MEMS microphone.

The MEMS microphone packaging structure according to the second embodiment of the present invention uses an insulating case having an electrode instead of a metal case. The PCB according to the second embodiment covers the open upper part of the case to seal the internal space of the case, and a sound hole is formed through a predetermined position. This allows external sound to flow directly into the PCB without going through the case's sound hole. In addition, the electrical signal output from the MEMS die of the PCB is transferred to the electrode of the case through the conductive spring.

The above and other objects and features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view of a MEMS microphone packaged according to a first embodiment of the present invention, FIG. 2 is an exploded perspective view of a MEMS microphone according to a first embodiment of the present invention, and FIG. 3 is an AA ′ of the MEMS microphone of FIG. 1. It is sectional drawing cut based on barbed line.

1 to 3, the MEMS microphone packaging structure according to an embodiment of the present invention includes a case 200, a first PCB 100a, a second PCB 100b, and a conductive spring 500. do.

The case 200 protects circuit elements such as the MEMS die 150, the ASIC, the amplifier, and the filter mounted on the first PCB 100a from external physical shocks and external electronic noise such as electromagnetic waves, and the case 200. There is formed a sound hole for transmitting the external voice signal to the internal MEMS die 150. In detail, the case 200 has a cylindrical shape in which one surface of the upper and lower surfaces is closed and the other surface is opened, and the external signal is transmitted to an internal circuit device, that is, the MEMS die 150, on one side of the closed surface. 1 sound hole 120a is formed. In addition, the case 200 may be made of a conductive material such as nickel, copper, aluminum, copper, or an alloy thereof having excellent electromagnetic wave blocking function.

The first PCB 100a has an internal element for converting a voice signal into an electric signal, that is, a MEMS die 150 having a diaphragm, an amplifier for amplifying and filtering the electric signal and transmitting the same to an external device (not shown); Circuit elements such as filters and ASICs are mounted using a method such as surface mount technology or wire bonding, and a conductive pattern for signal transmission between internal elements is formed. Meanwhile, the second sound hole 120b may be formed at the same position corresponding to the first sound hole 120a in the first PCB 100a, and the second sound hole 120b penetrating the first PCB 100a may be formed. ) Starts from the insulating layer and reaches the MEMS die 150 mounted on the opposite copper foil layer. For example, the reason for the formation of the second sound hole 120b is that, when the MEMS die 150 is not connected to the vertical lower portion of the first sound hole 120a and the second sound hole 120b, the external sound is directly added to the MEMS. This is to prevent the original voice signal from being attenuated and mixed with the MEMS die 150 due to being transmitted to the inner wall of the case 150 but not transmitted to the die 150 or flowing out to the outside. That is, by forming the second sound hole 120b corresponding to the first sound hole 120a of the case 200 on the mounting surface of the MEMS die 150 on the PCB, the noise is reduced and the conversion performance of the voice signal to the electrical signal is improved. The microphone sensitivity can be improved. In addition, by directly forming the second sound hole 120b in the first PCB 100a, a sufficient space (back chamber) between the first PCB 100a and the second PCB 100b may be secured to improve the performance of the microphone. have.

The second PCB 100b receives the electrical signal converted from the voice signal output from the first PCB 100a as described above, and the plurality of electrodes 220 are provided on the bottom surface to be applied to an external device (not shown). Is formed. The electrodes 220 may include a positive and negative electrode 220 for forming a capacitive structure on the MEMS die 150, and a ground electrode 220 for chassis grounding.

The conductive spring 500 serves as a conductive path for transferring an electrical signal generated in the first PCB 100a to the electrode of the second PCB 100b. That is, the conductive spring 500 forms a contact with the conductive pattern of the first PCB 100a and the electrode 220 of the second PCB 100b so that the mes die 150, the ASIC, the filter, etc. of the first PCB 100a are formed. The electrical signal output through the circuit element of the relay to the electrode of the second PCB (100b). To this end, the conductive spring 500 may be made of a material that is easily conductive, that is, aluminum, copper, nickel, or an alloy thereof. Meanwhile, various embodiments are possible in the form of the conductive spring 500, which will be described with reference to FIGS. 4 to 7.

4 to 7 are exemplary views showing the shape of various conductive springs according to an embodiment of the present invention.

4 to 7, the conductive spring according to the first embodiment of the present invention may be a conventional carbon steel or piano steel, but may be formed of an alloy material by alloying a metal with high electrical conductivity to improve conductivity. Can be.

The conductive spring 500 may use a coiled spring, which is generally used as shown in FIG. 4. However, if the middle portion of the conductive spring 500 is bent due to the force acting up and down when the first PCB 100a and the second PCB 100b are packaged, this may cause the conductive spring 500 to detach. Therefore, in order to prevent this, as shown in FIG. 5 or 6, the conductive spring 500 may form a conductive rod 530 that can support the coil spring 550. In addition, as illustrated in FIG. 7, coil springs 550 may be formed at both ends of the conductive bar 530. On the other hand, in the use of the conductive spring, any conductive spring such as a plate spring, a washer spring, as well as a general coil spring can be used.

8 is a cross-sectional view of a MEMS microphone packaged using a conductive spring according to the first embodiment of the present invention.

Referring to FIG. 8, in the MEMS microphone packaging structure, a spring support 510 may be formed on an upper surface of the first PCB 100a to facilitate coupling between the first PCB 100a and the conductive spring 500. The spring support 510 may be formed anywhere in the contact surface of the conductive spring 500 and the first PCB 100a or the contact surface of the conductive spring 500 and the second PCB 100b. Internal configuration of the MEMS microphone by stacking the case 200, the first PCB 100a, the conductive spring 500, and the second PCB 100b in order and curling the opening end 250 of the case 200. Maintain confidentiality between elements. Here, the case and the second PCB 100b may be combined with each other by laser welding, bonding using an adhesive, conductive paste, and the above-mentioned currying method.

In addition, in the coupling between the conductive spring 500 and the first PCB 100a and the second PCB 100b, various coupling methods such as SMT, conductive epoxy, laser welding, and bonding using an adhesive may be used.

Up to now, two PCBs conducting with the conductive springs according to the first embodiment of the present invention and a case for sealing them have been described. Hereinafter, a second embodiment in which a case of an insulating material having one PCB and an electrode formed thereon and a conductive spring for conducting the same will be described.

9 is an exploded perspective view of a MEMS microphone packaging structure according to a second embodiment of the present invention.

Referring to FIG. 9, the MEMS microphone packaging structure according to the embodiment of the present invention includes a PCB 1000, a case 2000, and a conductive spring 5000.

In the PCB 1000, a transducer, that is, a MEMS die 1500 in which a diaphragm is formed, and circuit elements such as an amplifier, a filter, and an ASIC are mounted using an SMT technique or a wire bonding technique. In addition, a sound hole 1200 for transmitting external sounds is formed on the mounting surface of the MEMS die 1500 on the PCB 1000.

Meanwhile, in the second embodiment of the present invention, a metal PCB having mechanical strength, heat resistance, and electromagnetic wave shielding function may be used in addition to the conventional PCB. Therefore, by using a metal PCB, it is possible to prevent PCB wear, cutting of conductive patterns due to bending, and separation of PCB mounting components, which may occur when the MEMS microphone is coupled to an external device.

The case 2000 closes the upper surface of the PCB 1000 to protect circuit elements such as the MEMS die 1500 mounted on the PCB 1000 from external physical shock and electronic noise. Meanwhile, an electrode 2200 may be formed in the case 2000 according to the second embodiment of the present invention. For this purpose, the case 2000 is formed of plastic or ceramic, which is an insulating material except for the electrode 2200. It is preferable.

As described in the first embodiment, the conductive spring 5000 conducts the electrode 2200 formed on the PCB 1000 and the case 2000 to transfer an electrical signal output from the PCB 1000 to the electrode 2200. The shape and characteristics of the conductive spring 5000 are the same as described in the first embodiment and will be omitted.

In the MEMS microphone packaging structure according to the second embodiment of the present invention, the PCB 1000 in which the sound hole 1200 is formed in the mounting portion of the MEMS die 1500 and the case 2000 in which the plurality of electrodes 200 are formed on one side of the lower surface thereof are formed. The conductive spring 5000 may be coupled between the SMT, the conductive epoxy, the laser welding, the conductive paste, and the like. In addition, as mentioned in the first embodiment, the spring support may be further provided to secure the coupling between the case 2000, the PCB 1000, and the conductive spring 5000.

On the other hand, in the embodiment of the present invention has been described using the poron as a material of the airtight layer so that the external sound is introduced into the MEMS die without attenuation, any material can be used if it has a property that can replace the purpose of the poron. will be.

In addition, it will be apparent that the embodiments of the present invention describe only the minimum embodiments for carrying out the present invention, and that various embodiments may be added and modified without departing from the spirit of the present invention.

As described above, the MEMS microphone packaging structure according to an embodiment of the present invention simplifies the MEMS microphone production process for forming a separate internal conductive path by connecting a PCB mounted with MEMS die and an external electrode with a spring of a conductive material. It provides an effect that can be done.

In addition, MEMS microphone packaging structure according to an embodiment of the present invention, the first PCB with the second sound hole and the second PCB formed with electrodes to correspond to the first sound hole formed in the case using a spring and the spring support of the conductive material As a result, the first PCB and the second PCB can be easily conducted.

Finally, according to an embodiment of the present invention, the MEMS microphone packaging structure includes a spring made of a conductive material so as to energize the first PCB having the second sound hole and the second PCB having the electrode corresponding to the first sound hole formed in the case. By applying SMT, conductive epoxy sealing, resistance and laser welding, it provides the effect of solidifying the electrical connection between the first PCB and the second PCB.

In addition, preferred embodiments of the present invention are disclosed for the purpose of illustration, those skilled in the art will be able to make various modifications, changes, additions, etc. within the spirit and scope of the present invention, such modifications and modifications belong to the scope of the claims You will have to look.

Claims (11)

A first printed circuit board having sound holes penetrating the upper and lower surfaces thereof; A mes die mounted on the first printed circuit board in correspondence with the sound hole position and converting a voice signal into an electric signal; A case in which a first sound hole is formed on one surface and a cylindrical shape in which the other surface is opened, and accommodates the first printed circuit board so that the first sound hole and the sound hole face each other; A second printed circuit board having a plurality of electrodes penetrating an upper surface and a lower surface thereof, the second printed circuit board being coupled to the opening surface of the case and sealing the inside of the case; And And a plurality of conductive springs inserted and fixed between the first printed circuit board and the second printed circuit board to transfer the electrical signal output from the MEMS die to the electrodes. . The method of claim 1, And the conductive spring is fixedly contacted between the first printed circuit board and the second printed circuit board by at least one of SMT, conductive epoxy, laser welding, and conductive paste. The method of claim 1, Memes microphone packaging structure characterized in that the spring support for supporting the conductive spring is formed on at least one of the contact surface of the first printed circuit board or the second printed circuit board. The method of claim 1, MEMS microphone packaging structure, characterized in that the conductive spring is at least one of coil spring, wash spring and plate spring. A cylindrical case in which a plurality of electrodes are formed on one surface and the other surface is opened; A printed circuit board covering the opening surface of the case to seal the internal space of the case and having a sound hole penetrated therethrough; A mes die mounted on the printed circuit board corresponding to the sound hole position and converting a voice signal into an electric signal; And And a plurality of conductive springs inserted between the printed circuit board and the case to transfer the electrical signal output from the MEMS die to the electrodes. The method of claim 5, wherein the conductive spring MEMS microphone packaging structure characterized in that the fixed contact between the first printed circuit board and the second printed circuit board by at least one of SMT, conductive epoxy, laser welding, conductive paste. The method of claim 5, wherein the case MEMS microphone packaging structure characterized in that the part except the electrode is made of an insulating material. The method of claim 7, wherein the insulating material MEMS microphone packaging structure, characterized in that the plastic or ceramic. The method of claim 5, wherein the PCB MEMS microphone packaging structure, characterized in that the metal PCB. The method of claim 5, Memes microphone packaging structure characterized in that the spring support for supporting the conductive spring is formed on at least one of the contact surface of the printed circuit board or the case. The method of claim 5, MEMS microphone packaging structure, characterized in that the conductive spring is at least one of coil spring, wash spring and plate spring.

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