KR100737728B1 - Packaging structure of mems microphone and construction method thereof - Google Patents

Abstract

A packaging structure of an MEMS(Micro Electro Mechanical System) microphone, and an assembly method thereof are provided to improve sensitivity and performance by forming a back-chamber hole and a back-chamber which enable air to flow in a second case. A packaging structure of an MEMS microphone includes a first case(10), a second case(20), and an FPCB(Flexible Printed Circuit Board)(30). A back-chamber space in which air flows is formed on the first case(10). A first plane of the first case(10) is opened and a second plane thereof is closed to support the MEMS microphone structure. A back-chamber hole is formed on the second plane of the first case(10) so that the air flows in the back-chamber space. A stepped unit which is extended from an end of the first plane is formed on an outer circumference plane of the first case(10). A space is formed to protect the MEMS microphone structure. A tone hole is formed on a third plane of the second case(20) to transfer an audio sound to the MEMS microphone structure. A fourth plane of the second case(20) is opened. The second case(20) wraps an outer wall of the second plane of the first case(10) which supports the MEMS microphone structure, and is coupled with the stepped unit of the first case(10). The FPCB(30) has a first part and a second part which are separated from a bending unit. The MEMS microphone structure is formed on the first part. An electrode for connecting with an external circuit is formed on the second part. The first part is put on the second plane having the back-chamber hole of the first case(10). The second part wraps the opened first plane of the first case(10).

Description

PACKAGING STRUCTURE OF MEMS MICROPHONE AND CONSTRUCTION METHOD THEREOF}

1 is an exploded perspective view of a packaging structure according to the present invention.

FIG. 2 is a rear perspective view of the first case shown in FIG. 1. FIG.

3a and 3b are assembled perspective views showing the assembled state of the packaging structure according to the present invention.

4a and 4b are cross-sectional views of the assembled state of the packaging structure according to the present invention.

<Description of the symbols for the main parts of the drawings>

10: first case 12: back chamber hole

20: second case 22: sound hole

24: Tightening groove 30: Flexible PCB (FPCB)

32: MEMS microphone structure 34: bent portion

The present invention relates to a packaging structure of the microphone and a method for assembling the same, and more particularly, to a packaging structure and a manufacturing method capable of securing a back chamber space in a MEMS microphone and reinforcing the tensile force of the case.

Microphones (also known as microphones) are devices that convert voice into electrical signals. The microphones include dynamic, condenser, ribbon, and ceramic types. The microphone has been greatly improved along with the rapid development of electric and electronic technologies, and in particular, as the development of small wired and wireless devices is accelerated, the size of the microphone is becoming smaller and smaller. In recent years, microphones using MEMS (Micro Electro Mechanical Systems / MEMS) technology have emerged.

MEMS technology refers to a microfabrication technology using an integrated circuit technology, especially in the existing semiconductor process, and is generally applied to fabricate micro sensors, actuators, and electromechanical structures. As MEMS technology has been applied to microphones, it has not only been able to innovatively reduce the thickness of various acoustic devices including the microphones, but also to reduce the power consumption and to apply them to various ranges.

However, the MEMS microphone has a problem that the back chamber space is not sufficiently secured because it is manufactured in a very small size. That is, as the back chamber, which is an essential space for allowing the air introduced through the sound hole to sufficiently vibrate, is not sufficiently secured, the sensitivity of the microphone decreases and the noise is mixed so that the performance is not sufficiently expressed.

In addition, when fabricating MEMS microphones, the metal thin film formed on the substrate and the case were directly laser welded to join the case and the substrate. When the welding temperature is high, the wiring formed on the substrate is damaged and the welding temperature is increased. In the low case, it was inconvenient to adjust the welding temperature carefully because the coupling was not made accurately. In addition, there is a problem that the joint part can be easily separated by a small impact after welding, so that the tensile force of the case does not meet the standards desired by the consumer.

The present invention is to solve the above problems, by forming a back chamber hole and a back chamber through which air can be introduced into the first case in which the MEMS microphone structure is placed to provide a sufficient back chamber space to improve sensitivity and performance. An object of the present invention is to provide a packaging structure of MEMS microphone and an assembly method thereof.

According to another embodiment of the present invention, by welding the first case on which the MEMS microphone structure is placed and the second case which is covered to protect the MEMS microphone structure, the wiring which can be generated by the direct laser welding of the substrate and the case. Another object of the present invention is to provide a packaging structure of MEMS microphone and an assembly method thereof, which can prevent damage to internal components and enhance case tension.

According to another embodiment of the present invention, after the laser welding of the first case and the second case by adding epoxy sealing to secure the coupling between the case, the packaging structure of the MEMS microphone that can further strengthen the case tension force and its assembly method The purpose is to provide.

In order to achieve the above object, it is a cylindrical shape having a back chamber space through which air can be introduced in accordance with the present invention, the first surface is open, the second surface is blocked to support the MEMS microphone structure, A back chamber hole through which air can flow into the back chamber space is formed, and an outer circumferential surface has a step portion extending from an end of the opened first surface such that the opened first surface protrudes from the second surface; 1 case; A cylindrical shape having a space formed to protect the MEMS microphone structure, the third surface of which is formed with a sound hole for transmitting sound to the MEMS microphone structure, the fourth surface of which is open, and which supports the MEMS microphone structure; A second case surrounding the outer wall of the second surface and coupled to a portion where the stepped portion of the first case is formed; And a first portion and a second portion divided by a bent portion, wherein the first portion of the MEMS microphone structure is formed, the second portion is formed of an electrode for connection with an external circuit, and the first portion. And a flexible substrate disposed on a second surface of which the back chamber hole of the first case is formed, and wherein the second portion surrounds and adheres to the opened first surface of the first case.

The packaging method of the MEMS microphone according to the embodiment of the present invention has a cylindrical shape in which a back chamber space into which air can be introduced is formed, and the first surface is opened, and the second surface is capable of supporting the MEMS microphone structure. A back chamber hole is formed that is blocked but allows air to flow into the back chamber space, and an outer circumferential surface has a step portion extending from an end of the opened first surface such that the opened first surface protrudes from the second surface. A first step of preparing a first case; A flexible substrate including a first portion and a second portion divided by a bent portion, wherein the first portion is formed of a MEMS microphone structure, and the second portion is formed of an electrode for connection with an external circuit. A second step of placing a first part on a second surface on which the back chamber hole of the first case is formed, and the second part surrounding and bonding the opened first surface of the first case; A cylindrical shape having a space formed to protect the MEMS microphone structure, the third surface of which has a sound hole formed to transmit sound to the MEMS microphone structure, and the fourth surface of the MEMS microphone structure having a second case opened A third step of enclosing the outer wall of the second surface of the first case supporting the second case and coupling the second case to a portion where the stepped portion of the first case is formed; And a fourth step of laser welding the joint portion of the first case and the second case.

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. Like reference numerals in the drawings denote like elements.

1 is an exploded perspective view of a packaging structure according to the present invention, Figure 2 is a rear perspective view of the first case shown in FIG.

Referring to FIG. 1, the packaging structure of a MEMS microphone according to the present invention is largely composed of a first case 10, a second case 20, and a flexible substrate 30.

As shown in the first case 10, one surface of the first case 10 is opened and the other surface of the first case 10 is closed. In addition, the cylindrical inner space is used as a back chamber (14 of FIG. 2) through which air can be introduced. The back chamber hole 12 is formed on the closed other surface of the first case 10 to allow air to flow into the back chamber space 14.

On the outer circumferential surface of the first case 10, a stepped portion 14 extending from one end of the open surface is formed so that the opened one surface protrudes from the blocked other surface. That is, the outer circumferential surface of the first case 10 is configured in such a manner that one open surface protrudes longer than the other circumference of the closed one surface. The reason for configuring the stepped portion 14 in this way is to facilitate the coupling with the second case 20 thereafter.

As shown, one surface of the second case 20 is blocked by a plate in which the sound holes 22 are formed so as to transmit sound to the MEMS microphone structure 32, and the other surface is opened in a cylindrical shape to protect the MEMS microphone structure 32. Is formed. In this case, it is preferable that the thickness of the other end 20a opened is equal to or narrower than the width W of the stepped portion 14 so that it can be mounted on the stepped portion 14 of the first case 10. .

In addition, a fastening groove 24 extending from the other surface opened to fix the bent portion 34 of the flexible substrate 30 may be formed on one side of the second case 20. At this time, in order to effectively fix the bent portion 34, the width of the fastening groove 24 and the width of the bent portion 34 is preferably formed the same.

The flexible substrate 30 is composed of a first portion 30a and a second portion 30b divided around the bent portion 34. The first portion 30a includes a signal conversion circuit that converts vibrations of the MEMS die and MEMS die into electrical signals due to the sound introduced into the sound hole 22 and the air introduced into the back chamber space 14, that is, the MEMS microphone. The structure 32 is mounted in a manner such as surface mount technology or wire bonding. In this case, it is preferable that a through hole 38 having a size corresponding to the back chamber hole 12 formed in the first case 10 is formed in a portion where the MEMS die is to be mounted. In the second portion 30b, an electrode 36 for connecting with an external circuit is formed. The flexible substrate 30 is packaged by bending the MEMS microphone structure 32 and the electrode 36 formed around the bent portion 34 to face outwards.

More specifically, the first portion 30a on which the MEMS microphone structure 32 is formed is placed on the blocked other surface of the first case 10. In this case, the first case 10 and the first portion 30a of the flexible substrate 30 may be heated or may not be moved so that the first portion 30a of the flexible substrate 30 does not move on the first case 10. It is fixed using a bonding method. In addition, the second portion 30b of the flexible substrate 30 is bonded to surround the opened surface of the first case 10. In this case, heat may be applied to the opened end of the first case 10 or may be fixed using various bonding methods. As described above, the bent portion 34 of the flexible board 30 is connected to the first case 10 and the second case 20 by the fastening groove 24 formed on one side of the second case 20. It is fixed to the side of the first case (10).

3A and 3B are assembled perspective views showing the assembled state of the packaging structure according to the present invention, and FIGS. 4A and 4B are sectional views of the assembled state of the packaging structure according to the present invention.

As shown, the first portion 30a of the flexible substrate 30 is placed on the other surface on which the back chamber hole 12 of the first case 10 is formed. In this case, it is preferable that the MEMS die of the MEMS microphone structure formed in the first portion 30a of the flexible substrate 30 is positioned on the back chamber hole 12. As described above, a through hole 38 through which air passes through is formed in a portion where the MEMS die is formed in the flexible substrate 30. The bent portion 34 formed on the flexible substrate 30 is bent along one side of the first case 10, and the second portion 30a surrounds the opened one surface of the first case 10. Are glued.

Thereafter, the fastening groove 24 of the second case 20 is positioned so as to fix the bent portion 34 that is bent along one side of the first case 10. Couple to the step (14). At this time, the second case 20 is formed to be coupled to the step portion 14 while surrounding the blocked other end side wall of the first case 10.

Subsequently, although not shown, the contact portion of the first case 10 and the second case 20 is fixed by laser welding. To this end, the first case 10 and the second case 20 is preferably formed using a metal material resistant to heat. As a result, the MEMS microphone packaging structure according to the present invention can have a case tensile force within a desired range.

At this time, in order to further strengthen the tensile force of the case and to solidify the bond may be further formed a seal 40 using an epoxy resin.

When the MEMS microphone package is assembled in this way, as shown in FIGS. 4A and 4B, the back chamber space 14 may be sufficiently secured in the first case 10, thereby greatly improving the sensitivity and performance of the MEMS microphone. have.

As described above, the packaging structure of the MEMS microphone and the manufacturing method thereof according to the present invention provide a sufficient back chamber space by forming a back chamber hole and a back chamber through which air can be introduced into the second case in which the MEMS microphone structure is placed. To improve sensitivity and performance.

Then, by laser welding the second case on which the MEMS microphone structure is placed and the first case covered to protect the MEMS microphone structure, damage to the wiring or internal components that may have occurred due to direct laser welding of the substrate and the case is prevented. And the case tension can be strengthened. In addition, an epoxy seal may be added after laser welding of the first case and the second case to strengthen the coupling between the cases, and may further strengthen the case tensile force.

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 should be regarded as belonging to the following claims. something to do.

Claims (13)

A bag having a back chamber space into which air can be introduced, wherein the first side is open and the second side is blocked to support the MEMS microphone structure, but the bag can enter air into the back chamber space. A first case having a chamber hole, the outer circumferential surface having a stepped portion extending from an end portion of the first surface opened such that the opened first surface protrudes from the second surface; A cylindrical shape having a space formed to protect the MEMS microphone structure, the third surface of which is formed with a sound hole for transmitting sound to the MEMS microphone structure, the fourth surface of which is open, and which supports the MEMS microphone structure; A second case surrounding the outer wall of the second surface and coupled to a portion where the stepped portion of the first case is formed; And And a first portion and a second portion divided by a bent portion, wherein the first portion is formed of the MEMS microphone structure, the second portion is formed with an electrode for connection with an external circuit, and the first portion is And a flexible substrate disposed on a second surface of the first case in which the back chamber hole is formed, and wherein the second portion wraps and adheres to the opened first surface of the first case. The method of claim 1, wherein the MEMS microphone structure, Is composed of a MEMS die vibrating due to the sound introduced into the sound hole and the air introduced into the back chamber space and a signal conversion circuit for changing the vibration of the MEMS die into an electrical signal, The flexible substrate may include a through hole through which the air passing through the MEMS die may be placed, and the MEMS die located on the through hole may be positioned at an upper portion of the back chamber hole formed in the first case. Packaging structure of a MEMS microphone, characterized in that placed so as to. delete According to claim 1, At the side of the second case, A fastening groove extending from the opened fourth surface of the second case is formed to fix the bent portion of the flexible substrate to the stepped portion of the first case, which is a portion where the second case and the first case are coupled. Packaging structure of a MEMS microphone, characterized in that. The width of the fastening groove formed in the second case, Packaging structure of a MEMS microphone, characterized in that the same as the width of the bent portion of the flexible substrate. The packaging structure of a MEMS microphone according to any one of claims 1 to 4, wherein laser welding is performed on a portion where the first case and the second case are coupled to each other. The packaging structure of a MEMS microphone according to claim 6, further comprising an epoxy resin seal formed at a portion where the first case and the second case are coupled to each other. A bag having a back chamber space into which air can be introduced, wherein the first side is open and the second side is blocked to support the MEMS microphone structure, but the bag can enter air into the back chamber space. A first step of preparing a first case in which a chamber hole is formed, and an outer circumferential surface has a stepped portion extending from an end of the first surface opened such that the first surface opened protrudes from the second surface; A flexible substrate including a first portion and a second portion divided by a bent portion, wherein the first portion is formed of a MEMS microphone structure, and the second portion is formed of an electrode for connection with an external circuit. A second step of placing a first part on a second surface on which the back chamber hole of the first case is formed, and the second part surrounding and bonding the opened first surface of the first case; A cylindrical shape having a space formed to protect the MEMS microphone structure, the third surface of which has a sound hole formed to transmit sound to the MEMS microphone structure, and the fourth surface of the MEMS microphone structure having a second case opened A third step of enclosing the outer wall of the second surface of the first case supporting the second case and coupling the second case to a portion where the stepped portion of the first case is formed; And And a fourth step of laser welding the joining portions of the first case and the second case to each other. The method of claim 8, wherein the MEMS microphone structure, Is composed of a MEMS die vibrating due to the sound introduced into the sound hole and the air introduced into the back chamber space and a signal conversion circuit for changing the vibration of the MEMS die into an electrical signal, The flexible substrate may include a through hole through which the air passing through the MEMS die may be placed, and the MEMS die located on the through hole may be positioned at an upper portion of the back chamber hole formed in the first case. Packaging assembly method of the MEMS microphone, characterized in that. delete The method of claim 8, wherein the side of the second case, A fastening groove extending from the opened fourth surface of the second case is formed to fix the bent portion of the flexible substrate to the stepped portion of the first case, which is a portion where the second case and the first case are coupled. Packaging assembly method of the MEMS microphone, characterized in that. The width of the fastening grooves formed in the second case, Packaging method of MEMS microphone, characterized in that the same as the width of the bent portion of the flexible substrate. The method according to any one of claims 8 to 11, wherein after the fourth step, And a fifth step of forming an epoxy resin seal in a portion where the first case and the second case are coupled to each other.

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