KR20240014981A - MEMS Microphone - Google Patents

Abstract

The MEMS microphone according to an embodiment of the present invention includes a substrate, a housing covering the substrate, a MEMS structure disposed on the substrate, and a signal processing element disposed on the substrate and spaced apart from the MEMS structure, and transmits the signal. The processing element is electrically connected to the substrate through a ball grid array (BGA) junction.

Description

MEMS Microphone

The present invention relates to a MEMS microphone, and more specifically, to a MEMS microphone in which signal processing elements are electrically connected using a ball grid array junction.

In general, audio devices generate sound by vibrating a diaphragm using electrodes, and with recent technological developments, great progress is being made in the field of audio devices. The fields in which these audio devices are used, such as portable terminals and hearing aids, are becoming more diverse, and as devices to which they are applied are becoming slimmer, the size of the audio devices themselves is also becoming more horizontal.

In addition, recently, a micro phone using MEMS (Micro Electro Mechanical Systems), a semiconductor technology, has been developed and used. MEMS is a technology that enables the fabrication of small mechanical components on the surface of a silicon wafer. These MEMS microphones can be divided into electrostatic and piezoelectric types, and include common condenser types.

Recently, mobile communication terminals such as mobile phones and smartphones, and electronic devices such as tablet PCs and MP3 players are becoming more compact. Accordingly, components of electronic devices are also becoming more compact. Therefore, Micro Electro Mechanical System (MEMS) technology that can solve the physical limitations of components is needed.

Public Patent Publication No. 10-2009-0039375

The technical problem to be solved by the present invention is to provide a MEMS microphone in which signal processing elements are electrically connected using a ball grid array junction.

In order to solve the above technical problem, the MEMS microphone according to an embodiment of the present invention includes a substrate; a housing covering the substrate; a MEMS structure disposed on the substrate; and a signal processing element disposed on the substrate and spaced apart from the MEMS structure, and the signal processing element is electrically connected to the substrate through a ball grid array (BGA) bond.

Additionally, the signal processing element may include a first substrate disposed on an upper surface, and the first substrate may be disposed on the substrate, so that the signal processing element and the substrate may be electrically connected.

Additionally, the signal processing element can be bonded to the first substrate using a flip chip method.

Additionally, the signal processing device may be in direct contact with the substrate through ball grid array (BGA) bonding.

Additionally, it may include a wire that electrically connects the MEMS structure and the substrate, and the signal processing element may be electrically connected to the MEMS structure through the substrate and the wire.

Additionally, the substrate includes a plurality of layers, and the wire and the signal processing element may be electrically connected inside the substrate.

Additionally, a hole may be formed in a region of the substrate facing the lower part of the MEMS structure.

Additionally, a hole may be formed in the housing area opposite the upper part of the MEMS structure.

Additionally, the signal processing element may be embedded in the substrate.

Additionally, it may include a capacitor embedded in the substrate.

According to embodiments of the present invention, the thickness of the MEMS microphone package can be reduced. Additionally, it is possible to prevent the shield can from rotating during soldering and reflow. Additionally, the length of the wire required can be reduced, resistance depending on the length of the wire can be reduced, and the signal-to-noise ratio (SNR) can be improved by increasing the internal volume.

In addition, by embedding ASIC, the quantity of wires, total wire length, and wire bonding can be reduced, En-cap application and drying processes can be eliminated, and noise can be improved. In addition, performance can be improved by mounting capacitors using the reduced space for wires and en-caps. Additionally, the overall package area can be reduced.

In addition, the size can be reduced because can solder and epoxy application areas are not required.

Figure 1 shows a MEMS microphone according to an embodiment of the present invention.
2 to 17 are diagrams for explaining the MEMS microphone according to the first embodiment of the present invention.
Figure 18 shows a MEMS microphone according to a second embodiment of the present invention.
19 to 29 are diagrams for explaining the MEMS microphone according to the second embodiment of the present invention.
Figure 30 shows a MEMS microphone according to a third embodiment of the present invention.
Figures 31 to 47 are diagrams for explaining the MEMS microphone according to the second embodiment of the present invention.
Figure 48 shows a MEMS microphone according to a fourth embodiment of the present invention.
Figures 49 to 54 are diagrams for explaining the MEMS microphone according to the fourth embodiment of the present invention.

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

However, the technical idea of the present invention is not limited to some of the described embodiments, but may be implemented in various different forms, and as long as it is within the scope of the technical idea of the present invention, one or more of the components may be optionally used between the embodiments. It can be used by combining or replacing.

In addition, terms (including technical and scientific terms) used in the embodiments of the present invention, unless explicitly specifically defined and described, are generally understood by those skilled in the art to which the present invention pertains. It can be interpreted as meaning, and the meaning of commonly used terms, such as terms defined in a dictionary, can be interpreted by considering the contextual meaning of the related technology.

Additionally, the terms used in the embodiments of the present invention are for describing the embodiments and are not intended to limit the present invention.

In this specification, the singular may also include the plural unless specifically stated in the phrase, and when described as "at least one (or more than one) of A and B and C", it is combined with A, B, and C. It can contain one or more of all possible combinations.

Additionally, in describing the components of the embodiments of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish the component from other components, and are not limited to the essence, order, or order of the component.

And, when a component is described as being 'connected', 'coupled', or 'connected' to another component, that component is directly 'connected', 'coupled', or 'connected' to that other component. In addition to cases, it may also include cases where the component is 'connected', 'coupled', or 'connected' by another component between that component and that other component.

Additionally, when described as being formed or disposed “on top” or “bottom” of each component, “top” or “bottom” means that the two components are directly adjacent to each other. This includes not only the case of contact, but also the case where one or more other components are formed or disposed between the two components. In addition, when expressed as “top” or “bottom,” the meaning of not only the upward direction but also the downward direction can be included based on one component.

Modifications according to this embodiment may include some components of each embodiment and some components of other embodiments. That is, the modified example may include one of the various embodiments, but some components may be omitted and some components of other corresponding embodiments may be included. Or, it could be the other way around. Features, structures, effects, etc. to be described in the embodiments are included in at least one embodiment and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects, etc. illustrated in each embodiment can be combined or modified and implemented in other embodiments by a person with ordinary knowledge in the field to which the embodiments belong. Therefore, contents related to such combinations and modifications should be interpreted as included in the scope of the embodiments.

Figure 1 shows a MEMS microphone according to an embodiment of the present invention, and Figures 2 to 17 are diagrams for explaining the MEMS microphone according to a first embodiment of the present invention.

The MEMS microphone 100 according to an embodiment of the present invention includes a substrate 110, a housing 120, a MEMS structure 130, and a signal processing element 140.

The substrate 110 is placed at the bottom of the MEMS microphone and has a plate shape. The substrate 110 forms an internal space together with the housing 120. The substrate 110 may include a printed circuit board (PCB), a semiconductor substrate, or a ceramic substrate. The substrate 110 may be composed of a single layer or may be formed by stacking a plurality of substrates.

A hole 131 may be formed in the substrate 110 at a position opposite to the lower part of the MEMS structure 130. The cross-sectional area of the hole 131 may be circular, but is not limited thereto. Here, the hole 131 may be an acoustic hole.

The housing 120 is disposed on the top of the MEMS microphone and has a cover shape that covers the substrate 110. The housing 120 covers the substrate 110 and forms an internal space. The housing 120 may be a can type made of metal or may be made of various materials such as plastic. The housing 120 may be combined with the substrate 110. At this time, the housing 120 may be combined with the substrate 110 by applying can solder or epoxy, and hardening the can solder or epoxy.

The MEMS structure 130 is disposed on the substrate 110. The MEMS structure 130 is disposed within the internal space formed by the substrate 110 and the housing 120. The MEMS structure 130 includes a body, a back plate, and a vibration plate. A body is stacked on the substrate 110, and a back plate and a vibration plate are placed on top of the body. Here, the diaphragm may be disposed on the top or bottom of the back plate. In FIG. 1, the back plate is shown as being located above the diaphragm, but it is natural that the diaphragm may also be located above the back plate. The position of the diaphragm may vary depending on the positions of the holes 131 and 132. Holes 131 and 132 are formed in the substrate 110 or housing 120, and when the diaphragm vibrates due to sound pressure caused by sound flowing in from the outside through the holes 131 and 132, the capacitance in the back plate is measured. This allows the acoustic signal to be sensed.

The signal sensed by the MEMS structure 130 is transmitted to the signal processing element 140. The MEMS structure 130 and the signal processing element 140 may be electrically connected. At this time, the MEMS structure 130 and the signal processing element 140 are connected to the wire 181 through wire bonding, and the signal sensed from the MEMS structure 130 through the wire 181 is sent to the signal processing element 140. It can be delivered.

The signal processing element 140 can process the electrical signal sensed and transmitted from the MEMS structure 130. The signal processing element 140 can amplify the signal sensed by the MEMS structure 130. Here, the signal processing element 140 may include, but is not limited to, an application-specific integrated circuit (ASIC). The signal processing element 140 may be formed as a single module. , may be formed in the form of a chip.The signal processing element 140 may include an ASIC and an En-cap on which the ASIC is applied.

The signal processing element 140 may be disposed on the substrate 110. At this time, the signal processing element 140 may be placed on the substrate 110 and spaced apart from the MEMS structure 130. It is placed together with the MEMS structure 130 in the internal space formed by the substrate 110 and the housing 120, and can receive signals from the MEMS structure 130. Since signals are transmitted between the MEMS structure 130 and the signal processing element 140 in the internal space covered by the housing 120, noise can be reduced. The signal processed in the signal processing element 140 is transmitted to the substrate 110, and may be transmitted through the substrate 110 to an outside that needs the signal. The signal processing element 140 and the substrate 110 may be electrically connected. The signal processing element 140 and the substrate 110 are connected to the wire 182 through wire bonding, and the signal processed in the signal processing element 140 can be transmitted to the substrate 110 through the wire 182. . In order to protect the wire bonding of the wires 181 and 182 of the signal processing element 140, En-Cap 190 can be applied and dried on the top of the signal processing element 140 to form a protection portion. Through this, the signal processing element 140 may not be exposed to the outside.

The signal transmitted to the substrate 110 may be transmitted to the outside through a terminal connected to the outside. At this time, the terminal connected to the outside must be exposed to the outside rather than the internal space, so it can be formed on the lower surface of the substrate 110. The signal processing element 140 is formed on a substrate, and a terminal connected to the outside can be formed at the bottom of the substrate, so that signals can be transmitted through a via hole connecting the upper and lower parts of the substrate 110. When the substrate 110 includes a plurality of layers, via holes may be formed to penetrate each layer.

Alternatively, the signal processing element 140 may be embedded within the substrate 110. By embedding the signal processing element 140 inside the substrate 110, the number of elements to be placed in the internal space where the substrate 110 and the housing 120 are formed can be reduced, thereby reducing the overall size, and the signal processing element 140 ) can be reduced with the MEMS structure 130 or the substrate 110, and wire bonding, epoxy application, and drying processes can be eliminated, thereby reducing the process. Additionally, the quality of acoustic sensing can be improved by reducing noise.

It is natural that in addition to the MEMS structure 130 and the signal processing element 140, other elements or modules, such as capacitors, may be disposed in the internal space where the substrate 110 and the housing 120 are formed. Other devices or modules may also be embedded in the substrate 110.

The substrate 110 includes a first area 150 where the MEMS structure 130 is located and a second area 160 where the housing 120 is located. At this time, the thickness of the first area 150 may be smaller than the thickness of the third area 170 where the signal processing element 140 is disposed. That is, a portion of the substrate 110 may form an empty space and have a cavity structure that is thinner than other portions. Due to the nature of the MEMS structure 130, the height from the substrate 110 is greater than that of the signal processing element 140, so it greatly affects the overall height of the MEMS microphone. At this time, the height of the MEMS microphone is increased by forming a cavity in which the thickness of the substrate 110 in the first area 150 where the MEMS structure 130 is placed is thinner than the area 170 where the signal processing element 140 is placed. It can be reduced.

In the MEMS microphone 10 according to a comparative example of the present invention, the MEMS structure 13 and the signal processing element 14 may be disposed on a substrate 11 having a constant thickness, as shown in FIGS. 3 and 4. Here, a hole 13-1 may be formed on the substrate 11, as shown in FIG. 3, or a hole 13-2 may be formed in the housing 12, as shown in FIG. 4. 3 or 4, the substrate 11 has a constant thickness, so the MEMS structure 13 and the signal processing element 14 are formed at a position with the same height, while the MEMS microphone (MEMS microphone) according to an embodiment of the present invention In 100, the cavity structure is formed in the substrate 110, so that the MEMS structure 130 is formed at a lower position than the signal processing element 140, thereby lowering the overall height. Additionally, by forming the cavity, the height difference between the MEMS structure 130 and the signal processing element 140 is reduced compared to the case where the cavity is not formed. That is, the length of the wire required for connection between the MEMS structure 130 and the signal processing element 140 is shortened, resistance depending on the length of the wire can be reduced, and signal loss can be improved.

By forming a cavity where not only the MEMS structure 130 but also the thickness of the second area where the housing 120 is disposed is thinner than other parts, the height of the housing 120 from the substrate 110 can also be reduced, and through this, the height of the MEMS microphone can be reduced. The height can be reduced. At this time, the thickness of the first area may be the same as the thickness of the second area. That is, the area where the MEMS structure 130 and the housing 120 are disposed can be formed to be thinner than other areas.

Here, the first area 150 may correspond to the shape of the MEMS structure 130, and the second area 160 may correspond to the shape of the housing 120. Figure 2 is a view of the MEMS microphone according to an embodiment of the present invention as seen from the top. The MEMS structure 130 may have a rectangular shape, and the cavity space of the first area 150 may be formed in a rectangular shape with an empty interior. there is. The cavity space of the first area 150 has an empty interior and may include a first bottom surface and a first side surface. At this time, the area where the cavity of the first region 150 is formed may be larger than the area of the MEMS structure 130. The MEMS structure 130 is located in the cavity of the first area 150, and the cavity of the first area 150 may be formed with a preset area so that the position does not deviate within an error range. At this time, a hole 131 penetrating the substrate 110 may be formed inside the first region 150 . Sound may flow in through the hole 131 to achieve sound sensing.

Since the housing 120 has a shape that covers the substrate 110, it is coupled to the substrate 110 along the edge, that is, the edge of the substrate 110. The second area 160 may be formed in the shape of a square band surrounding the edge of the substrate 110, corresponding to the shape in which the housing 120 is coupled to the substrate 110. At this time, the cavity space of the second area 160 may be formed to be open in the height direction and in an external direction perpendicular to the height direction, or may be formed to be open only in the height direction. When the cavity space of the second area 160 is open in the height direction and in an external direction perpendicular to the height direction, it may include a second bottom surface and an inner side surface. When the cavity space of the second area 160 is open only in the height direction, it may include a second bottom surface, an inner side, and an outer side.

Since the second area 160 has a shape corresponding to the shape of the housing 120 and has a cavity structure that is thinner and lower in height than the neighboring area, when the housing 120 is placed in the second area 160, Due to the step between the second area 160 and the neighboring area, the housing 120 may be fitted into the second area 160. The step between the second region 160 and the neighboring region serves to guide the housing 120 to the coupling position and can prevent the housing 120 from rotating when coupled with the substrate 110.

3 or 4, when the housing 12 is coupled to the substrate 11, if a structure to secure it is not formed, it is difficult to fix the position of the housing 120 during the curing process after applying can solder or epoxy. The position may change due to rotation or movement.

When curing can solder, shielding may be insufficient due to cold soldering or can rotation problems, and when applying epoxy, shielding may be insufficient if it is not applied evenly. To prevent this lack of shielding, a process for fixing the housing 12 may be necessary. However, the MEMS microphone 100 according to an embodiment of the present invention can be fitted through a cavity structure, and through this, the housing 120 can be coupled to the substrate 110 at an accurate position without separate fixation.

The area of the substrate where the signal processing element 140 is placed is the third area 170, and the third area 170 may be placed between the first area 150 and the second area 160. The third area 170 may correspond to the shape of the signal processing element 140. As shown in FIG. 2, the signal processing element 140 may have a rectangular shape, and accordingly, the third area 170 may also be formed in a rectangular shape. The area of the third area 170 may be larger than or equal to the area of the signal processing element 140. Areas of the substrate 110 other than the first area 150 and the second area 160 may have the same height as the third area 170 . Alternatively, like the first region 150 and the second region 160, the third region 170 may form a cavity and be formed to be thinner than regions other than the first to third regions. At this time, the third area 170 can guide or fix the position of the signal processing element 140.

The lower surface of the signal processing element 140 may be located closer to the housing 120 than the lower surface of the MEMS structure 130. Since the thickness of the third area 170 where the signal processing element 140 is located is thicker than the thickness of the first area 150 where the MEMS structure 130 is located, the signal processing element 140 is positioned in the height direction of FIG. The lower surface of the MEMS structure 130 is located closer to the housing 120 than the lower surface of the MEMS structure 130.

As shown in FIG. 5 , the MEMS microphone according to an embodiment of the present invention may have a hole 132 formed in the housing 120 rather than the substrate 110 at a position opposite to the upper part of the MEMS structure 130. The MEMS structure 130 can sense sound flowing in through the hole 132 formed in the housing 120.

As shown in FIG. 6, the MEMS microphone according to an embodiment of the present invention includes a substrate 110, a housing 120 covering the substrate 110, a MEMS structure 130 disposed on the substrate 110, and a MEMS structure 130. It includes a signal processing element 140 disposed on the substrate and spaced apart from the substrate 110, a first groove 151 in which the MEMS structure 130 is disposed, and a second groove in which the housing 120 is disposed ( 161) may be included. Here, the first groove 151 includes a first bottom surface 152 and a first side 153, and the second groove 161 includes a second bottom surface 162 and an inner side 163. And the first bottom surface 152 may be located on the same plane as the second bottom surface 163. Alternatively, the first bottom surface 152 may be parallel to the second bottom surface 163, but the distance from the bottom of the substrate 110 may be different. The cavity space of the MEMS microphone according to an embodiment of the present invention can be represented as a groove. That is, the substrate 110 includes a first groove 151 in which the MEMS structure 130 is disposed and a second groove 161 in which the housing 120 is disposed. The first groove 151 in which the MEMS structure 130 is disposed has a groove shape with an empty interior, and includes a first bottom surface 152 and a first side 153, in which the MEMS structure 130 is disposed. A first groove 151 that can be formed is formed.

The second groove 161 in which the housing 120 is disposed may be formed to be open in the height direction and in an external direction perpendicular to the height direction, as shown in FIG. 7, or may be formed to be open only in the height direction, as shown in FIG. 8. . When the second groove 161 is open in the height direction and in an external direction perpendicular to the height direction, it may include a second bottom surface 162 and an inner side surface 163, as shown in FIG. 7 . When the second groove 161 is open only in the height direction, it may include a second bottom surface 162, an inner side 163, and an outer side 164, as shown in FIG. 8.

As shown in FIG. 9 , the position of the MEMS structure 130 may be fixed in contact with the first side 153 of the first groove 151. Additionally, the inner surface of the housing 120 may be fixed in position by contacting the inner side 163 of the second groove 161. By fixing the position of the MEMS structure 130, problems such as breaking of the wire 181 connected to the signal processing element 140 due to a change in the position of the MEMS structure 130 can be prevented, and it is firmly fixed to ensure stability. can increase.

The housing 120 may be coupled to the substrate 110 through can soldering or epoxy while its inner surface is fixed in contact with the inner side 163 of the second groove 161. At this time, as shown in FIG. 10, solder 165 may be disposed between the second groove 161 and the housing 120. After applying the solder 165, it can be cured to join the housing 120 and the substrate 110.

In order to firmly bond the housing 120 and the substrate 110, a curing process may be performed by applying pressure during bonding. In the process of applying pressure, as shown in FIG. 11, a protrusion 166 through which the solder protrudes may be disposed between the inner side 163 of the second groove 161 and the housing.

The substrate 110 may include a third groove 171 in the third region 170 where the signal processing element 140 is disposed. As shown in FIG. 13, the third groove 171 may form a cavity space in which the signal processing element 140 can be placed. The third groove 171 may include a third bottom surface and a second side surface. The third bottom surface may be positioned on the same plane as the first bottom surface 152 or the second bottom surface 163. Alternatively, the third bottom surface may be parallel to the first bottom surface 152 or the second bottom surface 163, but may have different distances from the bottom of the substrate 110. The position of the signal processing element 140 may be fixed in contact with the second side of the third groove 171. As the position of the signal processing element 140 is fixed, the position of the signal processing element 140 changes, causing the wire 181 connected to the MEMS structure 130 or the wire 182 connected to the substrate 110 to break, etc. Problems can be prevented, and stability can be increased by being firmly fixed.

As previously mentioned, the substrate 110 may include multiple layers. The cavity of the first area 150 where the MEMS structure 130 is placed, the cavity of the second area 160 where the housing 120 is placed, or the cavity of the third area 170 where the signal processing element 140 is placed. The cavity, that is, the first groove 151, the second groove 161, or the third groove 171, may be formed by etching some of the upper layers of the plurality of layers of the substrate 110. When the substrate 110 is formed of a plurality of layers, a circuit can be formed in the lower layer space that overlaps the upper layer space forming the grooves 151 to 171.

As shown in FIG. 13, when the substrate 110 is composed of 1 to 4 layers, the cavity or first groove 151 of the first area 150 where the MEMS structure 130 is disposed is the first and second layers. The layer can be etched and a circuit can be constructed on the 3rd and 4th layers.

Considering the seating tolerance of the size of the MEMS structure 130, a weight may be applied to the size of the MEMS structure 130 on a one-side basis to form the cavity or first groove 151 of the first region 150. For example, when the MEMS structure 130 is 1 mm x 1 mm, the cavity or first groove 151 of the first area 150 is etched to be 1.4 mm x 1.4 mm on one side by applying a weight of 10% or more. can do.

When forming a circuit inside the substrate 110, interlayer connections use vias. In this case, drill vias or laser vias can be used. First, when applying Drill Via, vias or circuits cannot be applied to the entire 1st to 4th floor areas corresponding to the area to be etched, and vias and wiring must be designed and applied to avoid the etched area.

On the other hand, when applying a Laser Via, vias or circuits cannot be applied only to the 1st and 2nd floors corresponding to the area to be etched, and circuits cannot be applied to spaces (111) other than the vias of the 3rd and 4th floors. there is. When applying a laser via, the degree of freedom in via and circuit design can be increased compared to applying only a drill via. If the third groove 171 is not formed in the third area 170 where the signal processing element 140 is disposed, the signal processing element 140 is placed on the substrate 110 at the location where the signal processing element 140 is disposed. Since it is placed on the top, the circuit can be applied to the first to fourth layers without internal restrictions of the substrate 110 at that location.

The process of forming a cavity, that is, the etching process, can be formed through etching when stacking layers during the PCB manufacturing process. When using the manufacturing process, the thickness tolerance of the cavity area depending on the resin flow may be large. Alternatively, after completing the manufacturing of the substrate (PCB), post-processing can be performed using a laser.

The stacked substrate structure (Cavity PCB Stack) in which the cavity is formed can be applied to all Rigid PCB (FR4), Rigid Flex, and FPCB, and the amount of cavity reduction may vary depending on the thickness of the manufacturing fabric. Figure 14(A) is a case of applying a Rigid PCB, in which case it can be reduced by about 30% from 0.3 mm to 0.2 mm, and Figure 14(B) is a case of applying a Rigid Flex PCB, in this case it can be reduced from 0.23 mm. It can be reduced by 40% to 0.13 mm.

The MEMS microphone according to an embodiment of the present invention has an overall height D1, a height of the substrate D2, a height of the housing D3, a height of the step formed by the cavity D4, a height of the substrate in the area where the cavity is formed D5, and a MEMS structure 130. The height D6, the height D7 from the bottom of the substrate 110 to the MEMS structure 130, the separation distance D8 between the MEMS structure 130 and the signal processing element 140, the distance between the MEMS structure 130 and the signal processing element 140 It can be expressed as the height difference D9.

For example, D1: 0.9 mm, D2: 0.23 to 0.3 mm. Here, D2, the thickness of the substrate 110, may be 0.23 mm when the substrate 110 is a rigid PCB, and may be 0.3 mm when the substrate 110 is a rigid flex PCB. D3: 0.67 to 0.7 mm, D4: 0.1 mm, D5: 0.13 to 0.2 mm, D6: 0.35 mm, D7: 0.48 to 0.55 mm, D8: 0.21 mm, D9: 0.14 mm.

D1 to D8 may have a certain ratio to each other. D5/D3, which is the height of the substrate in the cavity regions 150 and 160 to the height of the housing 120, can be formed at a ratio of 0.1 to 0.3, and D2/D1, which is the height of the substrate 110 to the overall height, is 0.2 to 0.4. It can be formed at a ratio of , and D7/D2, which is the height from the substrate 110 to the MEMS structure 130 to the height of the substrate 110, can be formed at a ratio of 0.6 to 0.8.

D1 to D8 may vary depending on the design specifications of the MEMS microphone, the size of the MEMS structure 130, and the signal processing element 140.

When implementing a MEMS microphone of the same size without reducing the size, the internal back-volume can be increased depending on whether a cavity or groove is applied, and through this, the signal-to-noise ratio (SNR) can be improved. In addition to the cavity, the back-volume may vary depending on whether a rigid PCB or a rigid flex PCB is used as the substrate.

The main factors needed to calculate back-volume can be used as D4, D8, and D9 in FIG. 15. D4 is the thickness of the cavity, D8 is the distance between the MEMS structure and the signal processing element, and D9 is the difference in seating height between the MEMS structure and the signal processing element.

As shown in Figure 16, Back-Volume can be compared for each case. Figure 16(A) is a case in which a cavity is not applied to a rigid PCB, Figure 16(B) is a case in which a cavity is applied to a rigid PCB, and Figure 16(C) is a case in which a cavity is applied to a rigid flex PCB. D11 may be 0.9 mm, D12 may be 0.3 mm, and D13 may be 0.23 mm. In this case, D4, D8, and D9 in FIGS. 16(B) and 16(C) may be as follows.

item Rigid PCB+Cavity Rigid Flex PCB+Cavity D4(um) 104 104 D8(um) 13 13 D9(um) 46 46

The Back-Volume for each case is different as shown in Figure 17. In the case of Rigid PCB + Cavity, the Back-Volume increases by 5% compared to the case in which no cavity is applied to the Rigid PCB, and in the case of Rigid Flex PCB + Cavity, the Back-Volume increases by 5%. Compared to the case where the cavity was not applied to the rigid PCB, it can be seen that the back-volume increases by 14%. As above, as the internal back-volume increases, in the case of rigid PCB + cavity, the cavity on the rigid PCB increases. Compared to the case where no cavity was applied, the signal-to-noise ratio can be improved to the level of 2%, and in the case of Rigid Flex PCB + Cavity, the signal-to-noise ratio can be improved to the level of 5% compared to the case where the cavity is not applied to the Rigid PCB.

Figure 18 shows a MEMS microphone according to a second embodiment of the present invention, and Figures 19 to 29 are diagrams for explaining the MEMS microphone according to a second embodiment of the present invention.

The MEMS microphone 200 according to the second embodiment of the present invention includes a substrate 210, a housing 220 covering the substrate 210, a MEMS structure 230 disposed on the substrate 210, and an interior of the substrate 210. It consists of a signal processing element 240 embedded in the. Among the detailed descriptions of the substrate 210, the housing 220, the MEMS structure 230, and the signal processing element 240, descriptions that overlap with the detailed descriptions of each component of FIGS. 1 to 17 will be omitted below. do.

The signal processing element 240 may be embedded inside the substrate 210. As shown in FIG. 18, the signal processing element 240 is embedded inside the substrate 210 to form the substrate 210 and the housing 220. ) can be reduced in the internal space where the overall size is formed, and the process of electrically connecting the signal processing element 240 to the MEMS structure 230 or the substrate 210 can be reduced. The process can be reduced by eliminating wire bonding, epoxy application, and drying processes, etc. Additionally, the quality of acoustic sensing can be improved by reducing noise.

The signal processing element 240 is embedded inside the substrate 210 and can be electrically connected to the substrate 210 from within the substrate 210. The MEMS structure 230 is located on the substrate 210 and includes a wire 250 that electrically connects the MEMS structure 230 and the substrate 210, and the signal processing element 240 is formed on the substrate 210. It can be electrically connected to the MEMS structure through vias and wires 250. That is, the signal processing element 240 is electrically connected to the MEMS structure 230 through the wire 250 and the via of the substrate 210, and the signal sensed from the MEMS structure 230 is transmitted to the signal processing element 240. It is delivered. The MEMS structure 230 and the signal processing element 240 may be electrically connected. At this time, the MEMS structure 230 and the substrate 210 are connected to the wire 250 through wire bonding, and the signal processing element 240 is connected to the substrate 210 through a via, and through the wire 250 and the via. The signal sensed by the MEMS structure 230 may be transmitted to the signal processing element 240.

The signal processing element 240 can process the electrical signal sensed and transmitted from the MEMS structure 230. The signal processing element 240 can amplify the signal sensed by the MEMS structure 230. Here, the signal processing element 140 may include, but is not limited to, an application-specific integrated circuit (ASIC). The signal processed by the signal processing element 240 is transmitted to the substrate 210. and can be transmitted to the outside that needs the signal through the substrate 210. The signal processing element 240 and the substrate 210 may be electrically connected. The signal processing element 240 and the substrate ( 210) is connected to a via of the board 210, so that the signal processed in the signal processing element 240 can be transmitted to the board 210. The signal transmitted to the board 210 is transmitted through a terminal connected to the outside. It can be transmitted to the outside. At this time, the terminal connected to the outside must be exposed to the outside rather than the internal space, so it can be formed on the lower surface of the board 210. The signal processing element 240 is embedded inside the board. , a terminal connected to the outside may be formed in the lower part of the board 210, and a signal can be transmitted through a via connecting the signal processing element 240 and the lower part of the board 210.

The signal processing element 240 is embedded inside the substrate 210, and the signal processing element 240 and the substrate 210 are electrically connected inside the substrate, so that the signal processing element 240 and the substrate 210 are connected to each other. No wires are needed to connect electrically. Therefore, as shown in FIG. 19, only the wire 250 for electrically connecting the MEMS structure 230 and the substrate 210 is needed, and the wire 182 for electrically connecting the signal processing element 240 and the substrate 210 is needed. ) is not required, so wire bonding is unnecessary. In addition, since the signal processing element 240 is embedded inside the substrate 210, the En-cap 190 for protecting the signal processing element 240 is also unnecessary, so the epoxy application and drying processes can be eliminated. The process can be shortened.

The substrate 210 may include multiple layers. At this time, the signal processing element 240 is disposed in a cavity space formed in at least one layer among the plurality of layers, and is electrically connected to the wire 250 through a via hole formed in the substrate 210. It can be connected to . In order to embed the signal processing element 240 in the substrate 210, a cavity space in which the signal processing element 240 can be placed can be formed inside the substrate 210. To this end, the substrate 210 includes a plurality of layers, an empty space is formed in a partial area of at least one layer among the plurality of layers, and the signal processing element 240 is embedded in the corresponding location to form an empty space inside the substrate 210. It can be embedded in .

At least a portion of the signal processing element 240 may overlap with at least a portion of the MEMS structure 230 in a first direction, which is the upper and lower direction of the substrate 210. Here, the first direction may be a direction perpendicular to the top surface of the substrate 210. The MEMS structure 230 is disposed on the upper surface of the substrate 210, and the signal processing element 240 is embedded within the substrate 210, so even if they overlap in the first direction, they do not impose spatial restrictions on each other. By partially overlapping the 240 and the MEMS structure 230, the gap between them can be narrowed. Through this, the overall size of the MEMS microphone can be reduced, and the length of the path for electrically connecting the signal processing element 240 and the MEMS structure 230 can be reduced. Additionally, by increasing space utilization, the space needed to mount other components can be secured.

Alternatively, as shown in FIG. 20, the signal processing element 240 may not overlap the MEMS structure 230 and the substrate 210 in the first direction, which is the upper and lower direction. When the signal processing element 240 overlaps the MEMS structure 230 and the substrate 210 in the first direction, which is the upper and lower direction, an empty space is located in the lower region of the body of the MEMS structure 230, thereby causing vibration of the diaphragm. It can have an impact. Therefore, the signal processing element 240 is embedded inside the substrate 210, but the signal processing element 240 is oriented in the first direction so as not to overlap in the first direction, which is the upper and lower direction of the MEMS structure 230 and the substrate 210. It can be formed by being spaced apart in a second direction perpendicular to the. In addition, by embedding the signal processing element 240 inside the substrate 210, the upper area of the substrate 210 where the signal processing element 240 is embedded can be used, and the substrate in the area where the MEMS structure 230 is disposed can be used. (210) The internal region can constitute other circuits.

It may include at least one first element 261 embedded within the substrate 210 and spaced apart from the signal processing element 240. In addition to the signal processing element 240, the first element 261 can be embedded in a position that does not affect the arrangement of the signal processing element 240, as shown in FIG. 21. Here, the first element 261 may be a capacitor element. By embedding the first element 261, which is a capacitor element, the capacitance increases, and through this, noise-related performance such as SNR, PSRR, and PSR can be improved.

Here, at least a portion of the first element 261 may overlap with at least a portion of the MEMS structure 230 in the first direction. The MEMS structure 230 is disposed on the upper surface of the substrate 210, and the first element 261 is embedded inside the substrate 210, so even if they overlap in the first direction, there is no spatial restriction on the first element. By partially overlapping the (261) and the MEMS structure (230), the gap between them can be narrowed. Through this, the overall size of the MEMS microphone can be reduced, space utilization can be increased, and the space needed to mount other components can be secured.

It may include at least one second element 262 disposed on the substrate 210. At this time, at least a portion of the second element 262 may overlap with at least a portion of the signal processing element 240 in the first direction. By embedding the signal processing element 240 inside the substrate 210, space for placing other elements is secured in the upper surface area of the substrate 210, which corresponds to the upper area of the signal processing element 240. 2 elements 262 can be placed. Here, the second element 262 may be a capacitor element. By including at least one of the first element 261 and the second element 262, the capacitor element can be placed close to the signal processing element 240, thereby increasing the capacitance, thereby reducing noise such as SNR, PSRR, and PSR. Related performance can be improved.

Unlike the hole 231 formed in the substrate area facing the lower part of the MEMS structure 230 in FIG. 20, the hole 232 is formed in the housing 220 area facing the upper part of the MEMS structure 230, as shown in FIG. 23. can be formed. When the hole 231 is formed in the substrate area, there may be restrictions on the area of the substrate 210 in which the signal processing element 240 is embedded depending on the positions of the holes 231 and 232. However, when the hole 232 is formed in the housing area, the hole is not formed in the substrate 210, so when embedding the signal processing element 240 inside the substrate 210, there are no restrictions due to the hole. You can. Therefore, more free design is possible.

As shown in FIG. 24, when comparing the case where the signal processing element 240 is located on the upper part of the substrate 210 (FIG. 24(A)) and the case where the signal processing element 240 is embedded (FIG. 24(B)), As shown in Figure 25, it can be seen that the internal volume (Back-Volume) increases as the signal processing element 240 and the wire 250 connecting the signal processing element 240 and the substrate 210 are deleted. For example, ^when the volume of the ASIC, which is the signal processing element 240, is 0.784 As a result of deletion, Back-Volume also increases to 3%. In other words, Back-Volume increases to about 6%. As described above, as the internal back-volume increases, the signal-to-noise ratio can be improved.

In addition, when placing a capacitor in the space secured by removing the signal processing element 240 and the wire 250 connecting the signal processing element 240 and the substrate 210, the internal volume (Back-Volume) depends on the capacitor. ) is not reduced, and performance can be improved depending on the capacitor while maintaining the same internal volume. For example, ^when the volume of the ASIC ^, which is the signal processing element 240, is 0.784 In this way, it can be seen that there is almost no change in volume, and performance can be improved by increasing capacitance.

As shown in FIG. 26, when the signal processing element 240 is located on the upper part of the substrate 210 (FIG. 26(A)) and when the signal processing element 240 is embedded and located close to the MEMS structure 230 (FIG. Comparing 26(B)), the size of the MEMS structure can be reduced, as shown in FIGS. 27 and 28. For example, D21 may be 3 mm, D31 may be 2 mm, D22 may be 2.9 mm, and D32 may be 1.72 mm. In this way, it can be seen that the size is reduced by about 17%.

As described above, by embedding the signal processing element 240, the length of the wiring formed on the upper layer of the substrate 210 can be reduced, and the number of bonding pads can be reduced from 6 points to 3 points, thereby reducing the exposure of the wiring and bonding pad. Performance loss and shielding can be improved. In addition, the bottom of the substrate 210 can also be reduced in length or deleted, thereby improving performance loss and shielding. In addition, as shown in FIG. 29, the wire connecting the signal processing element 240 and the substrate 210 can be deleted, reducing the total required wires from 9 (FIG. 29(A)-251 and 252) to 3 (FIG. 29). (B)-251), and the total wire length is also reduced. Material cost, process cost, ST, and BOM (Bill of Material) can be improved by reducing the quantity and length of wire and simplifying the process accordingly. Furthermore, in addition to the existing capacitor 262, an additional capacitor 263 can be mounted in the upper area of the embedded signal processing element 240. At this time, the internal volume does not decrease even when two capacitors 262 and 263 are mounted, and performance can be improved by increasing capacitance.

MIC Bias If Bypass Cap is applied to each AVDD and DVDD, additional performance improvement is possible when MIC is operating in a sleep scenario. At this time, noise-related performance such as SNR, PSRR, and PSR can be improved.

Figure 30 shows a MEMS microphone according to a third embodiment of the present invention, and Figures 31 to 47 are diagrams for explaining the MEMS microphone according to a second embodiment of the present invention.

The MEMS microphone 300 according to the third embodiment of the present invention includes a first substrate 310, a second substrate 320, a housing 330, a MEMS structure 340, and a signal processing element 350.

The first substrate 310 is disposed at the bottom of the MEMS microphone and has a plate shape. The first substrate 310 is a flexible substrate and may be a chip on film (COF) substrate or a flexible printed circuit board (FPCB). A COF (Chip on Film) substrate is a substrate formed by mounting devices such as chips on a base film. It has a film shape and is considerably thinner than other substrates. By using a COF substrate as the substrate for the MEMS microphone, the thickness can be significantly reduced. When using only a rigid board, it is not easy to apply fine pitch, but when using a COF board, fine pitch is possible, allowing the size of the MEMS microphone package to be reduced by more than 50%. A flexible printed circuit board (FPCB) is a flexible printed circuit board. It is also flexible and has a thinner thickness than a regular PCB, so the thickness can be significantly reduced by using a flexible printed circuit board as the board for the MEMS microphone. In addition, other types of flexible substrates may be included. The first substrate 310 is electrically connected to the signal processing element 350.

The second substrate 320 is stacked on the first substrate 310 and has a plate shape. The second substrate 320 is a rigid substrate and may be a sus or reinforcement plate. SUS is a steel grade mixed with iron and chromium to enhance corrosion resistance and is a high-strength substrate. In addition, various reinforcing plates made of metal can be used. In addition, it may include other types of rigid substrates that can be combined with the housing to maintain the shield. The second substrate 320 is a substrate to supplement the rigidity of the first substrate 310, and is bonded to the housing 330 to provide a shield for the internal space.

Hereinafter, the first substrate 310 will be described as a flexible substrate, and the second substrate 320 will be described as a rigid substrate.

The housing 330 is disposed on the top of the MEMS microphone and has a cover shape that covers the rigid substrate 320. The housing 330 covers the rigid substrate 320 to form an internal space. The housing 330 may be a can type made of metal or may be made of various materials such as plastic. The housing 330 may be combined with the rigid substrate 320. At this time, the housing 330 and the rigid substrate 320 may be joined by welding. The area where the housing 330 and the rigid substrate 320 are joined may be joined by micro welding. By joining the housing 330 and the rigid board 320 by micro welding, the process of applying and hardening can solder or epoxy is unnecessary, and the can solder line or epoxy application area is also unnecessary, so the size can be adjusted to the corresponding area. It can be reduced.

A MEMS structure 340 and a signal processing element 350 may be disposed on the rigid substrate 320. The MEMS structure 340 is disposed within the internal space formed by the rigid substrate 320 and the housing 330. The MEMS structure 340 includes a body, a back plate, and a vibration plate. A hole 341 may be formed in the flexible substrate 310 and the rigid substrate 320 at a position opposite to the lower part of the MEMS structure 340. The cross-sectional area of the hole 341 may be circular, but is not limited thereto. Here, the hole 341 may be an acoustic hole. The hole may be formed in an area of the housing 330 facing the upper part of the MEMS structure 340. In addition to being formed in the area of the housing 330, the hole corresponds to the hole 341 in FIG. 30.

A hole 341 is formed in the flexible substrate 310 and the rigid substrate 320 or the housing 330, and when the diaphragm vibrates due to sound pressure caused by sound flowing in from the outside through the hole 341, the sound in the back plate You can sense an acoustic signal by measuring capacitance. In FIG. 30, the back plate is shown as being located above the diaphragm, but it is natural that the diaphragm may also be located above the back plate.

The signal sensed by the MEMS structure 340 is transmitted to the signal processing element 350. The MEMS structure 340 and the signal processing element 350 may be electrically connected. At this time, the MEMS structure 340 and the signal processing element 350 are connected to the wire 381 through wire bonding, and the signal sensed from the MEMS structure 340 through the wire 381 is sent to the signal processing element 350. It can be delivered.

The signal processing element 350 can process the electrical signal sensed and transmitted from the MEMS structure 340. The signal processing element 350 can amplify the signal sensed by the MEMS structure 340. Here, the signal processing element 350 may include, but is not limited to, an application-specific integrated circuit (ASIC). The signal processing element 350 may be formed as a single module or may be formed in the form of a chip. The signal processing element 350 may include an ASIC and an En-cap for applying the ASIC.

The signal processing element 350 may be disposed on the rigid substrate 320. At this time, the signal processing element 350 may be placed on the rigid substrate 320 and spaced apart from the MEMS structure 340. It is placed together with the MEMS structure 340 in the internal space formed by the rigid substrate 320 and the housing 330, and can receive signals from the MEMS structure 340. Since signals are transmitted between the MEMS structure 340 and the signal processing element 350 in the internal space covered by the housing 330, noise can be reduced. The signal processing element 350 is electrically connected to the flexible substrate 310. The signal processed in the signal processing element 350 is transmitted to the flexible substrate 310, and can be transmitted to an outside that needs the signal through the flexible substrate 310.

As shown in FIGS. 31 and 32, the signal processing element 350 receives a signal from the MEMS structure 340 through the wire 381, and the wire 382 passes through the hole 321 formed in the rigid substrate 320. ) can be connected to the flexible substrate 310. A wire pad 360 is formed on the flexible substrate 310 on the side where it is joined to the rigid substrate 320, and can be connected to the wire 382 of the signal processing element 350 through the wire pad 360.

The signal processing element 350 and the flexible substrate 310 are connected to the wire 382 through wire bonding, and the signal processed by the signal processing element 350 is transmitted to the flexible substrate 310 through the wire 382. You can. In order to protect the wire bonding of the wires 381 and 182 of the signal processing element 350, En-Cap can be applied and dried on the top of the signal processing element 350 to form a protection portion. Through this, the signal processing element 350 may not be exposed to the outside.

The signal transmitted to the flexible substrate 310 may be transmitted to the outside through a terminal connected to the outside. At this time, the terminal connected to the outside must be exposed to the outside rather than the inside space, so it can be formed on the lower surface of the flexible substrate 310. The signal processing element 350 is connected to the flexible substrate 310, and a terminal connected to the outside can be formed in the lower part of the flexible substrate 310, and a via hole connecting the upper and lower parts of the flexible substrate 310 is formed. Signals can be transmitted through When the flexible substrate 310 includes a plurality of layers, via holes may be formed to penetrate each layer.

Alternatively, the signal processing element 350 may be embedded within the flexible substrate 310 or the rigid substrate 320. By embedding the signal processing element 350 inside the flexible substrate 310 or the rigid substrate 320, the number of elements to be placed in the internal space where the rigid substrate 320 and the housing 330 are formed can be reduced, thereby reducing the overall size. The process of connecting the signal processing element 350 to the MEMS structure 340 or the flexible substrate 310 can be reduced, and wire bonding, epoxy application and drying processes, etc. can be eliminated, thereby reducing the process. . Additionally, the quality of acoustic sensing can be improved by reducing noise.

The rigid substrate 320 is stacked on the flexible substrate 310, and may be bonded by thermal compression. Alternatively, it may be bonded with conductive double-sided tape or the like. In addition, as shown in FIG. 33, an adhesive layer 390 can be formed between the bonding surface of the flexible substrate 310 and the rigid substrate 320. An adhesive may be applied to the adhesive layer 390 or a conductive double-sided tape may be placed on it. The flexible substrate 310 and the rigid substrate 320 may be bonded in various ways to perform inter-substrate bonding.

The signal processing element 350 may be disposed on the flexible substrate 310. The rigid substrate 320 may not be laminated at a location where the signal processing element 350 is disposed. At this time, a hole corresponding to the shape of the signal processing element 350 may be formed in the rigid substrate 320. The signal processing element 350 may be directly bonded to the flexible substrate 310 in the area where the hole of the rigid substrate 320 is formed.

The signal processing element 350 can be bonded to the first substrate 351 using a flip chip method to form a flip chip BGA and bonded to the flexible substrate 310. When attaching a chip to a substrate, flip chip is a method of fusing the chip using the electrode pattern on the bottom of the chip without using additional connection structures such as metal leads (wires) or intermediate media such as ball grid array (BGA). Ball Grid Array (BGA) is a type of surface-mounted package in which ball-shaped solder 350 is arranged in a grid. It is a leadless joint, and the jointed package is the same size as the chip, making it small and compact. It is advantageous for weight reduction and the distance between electrodes can be made much finer. As shown in Figure 34, the signal processing element 350 is placed on the third substrate 351 in a flip chip manner to form a flip chip BGA, and the flip chip BGA itself is placed on the flexible substrate 310 by ball grid array bonding. can be placed. At this time, the signal of the MEMS structure 340 is transmitted to the flexible substrate 310 through the wire 381 connected to the flexible substrate 310 through wire bonding, and is transmitted to the signal processing element 350 through the flexible substrate 310. It can be delivered.

The MEMS structure 340 and the housing 330 are disposed on the rigid substrate 320 at the position where the rigid substrate 320 is stacked, and can be firmly and stably coupled to each other. That is, for signal transmission, the signal processing element 350, which must be electrically connected, is directly coupled to the flexible substrate 310 rather than the rigid substrate 320, and the housing 330, which requires a sturdy shield, or the MEMS, which requires stable sensing, Structure 340 may be bonded to rigid substrate 320 .

The signal processing element 350 itself can be electrically connected to the wire pad of the flexible substrate 310 using the BGA method rather than the flip chip method. As shown in FIG. 35, it can be directly connected to the flexible substrate 310 without an additional third substrate 351.

By arranging the signal processing element 350 on the flexible substrate 310 using the BGA method, wire bonding can be reduced, and En-Cap application and drying processes are unnecessary. There is no need for a wire from the signal processing element 350 to the flexible substrate 310, so only three wires connecting from the MEMS structure 340 to the flexible substrate 310 are needed, and the flexible Six wires to the substrate 310 and the total wire length can be reduced. By using the BGA method, noise is improved and the wire and En-Cap application area can be utilized, increasing the degree of freedom in design.

The wire bonding between the MEMS structure 340 and the flexible substrate 310 is connected in the area between the MEMS structure 340 and the signal processing element 350, or, as shown in FIGS. 36 and 37, the position of the signal processing element 350 The wire 381 may be connected to the flexible substrate 310 at a position corresponding to the side of the signal processing element 350 within a range that does not overlap. In this case, the wire 381 does not need to be connected to the flexible substrate 310 between the MEMS structure 340 and the signal processing element 350, and the MEMS structure 340 and the signal processing element 350 are shown in FIG. 35. It can be placed closer than before.

Alternatively, as shown in Figures 38 and 39, the direction of the wire may be rotated by 90 degrees and placed. In Figures 36 and 37, the direction of the wire is toward the signal processing element 350, while in Figures 38 and 39, the direction of the wire is not toward the signal processing element 350. By securing the freedom of wire wiring of the MEMS structure 340, space can be efficiently utilized and the size can be reduced.

The rigid substrate 320 may not be laminated on the edge area of the flexible substrate 310 corresponding to the contact portion of the housing 330 so that the housing 330 is not laminated on the rigid substrate 320 . As shown in FIG. 40, the housing 330 is laminated on the upper part of the flexible substrate 310 rather than the rigid substrate 320, and the outer side of the rigid substrate 320 and the inner side of the housing 330 are in contact with each other, so that the side surface It can be combined in any direction to form a shield. At this time, the housing 330 may be fitted onto the outer side of the rigid substrate 320 due to the step formed between the rigid substrate 320 and the flexible substrate 310. Through this, it is possible to prevent the housing 330 from rotating when coupled.

When the MEMS structure 340 and the signal processing element 350 are connected with a wire, and the signal processing element 350 and the flexible substrate 310 are also connected with a wire, as shown in FIG. 41, on the top of the signal processing element 350 En-Cap (370) can be applied.

When welding the rigid substrate 320 and the housing 330, the width of the can-lead of the housing 330 can be reduced by performing sealing welding. As shown in Figure 42, the contact area between the housing 330 and the rigid substrate 320 during sealing welding can be reduced, and through this, the size can be reduced.

As previously described, the flexible substrate 310 may be a COF substrate. When using a COF substrate, a significantly fine pitch can be applied, as shown below, compared to when using rigid, rigid flex, or FPCB.

Figure 43 shows the difference when implemented using a COF substrate and another substrate. Figure 43(A) shows that when using rigid, rigid flex, or FPCB, a shield can SMT line (A1) is required, and the pattern The sizes of (Pt) and vias are significant. However, as shown in Figures 43(B) and 43(C), when using a COF substrate, SUS and COF GND Contact PSR Open areas of a size smaller than the shield can SMT line (A1) are required, and the pattern (Pt) and , it can be seen that the size of the via becomes significantly smaller.

By applying the Fine Pitct Rule, it is advantageous to improve noise by increasing the GND Copper area, and the degree of freedom in design is significantly increased by applying Fine Pitch compared to other PCB specifications in the same wiring space area. In addition, space can be secured due to high size utilization, so devices such as capacitors (c) can be mounted, as shown in Figure 43(C). This can be more advantageous in improving performance and noise. In addition, since circuit design space is secured and various structures can be designed, there is more room for performance improvement.

When using a COF substrate with multiple layers (2 layers), a 3-layer effect can be applied to the circuit through a heat-compression structure with sus. At this time, the source can act as a GND circuit to reduce the effect of noise. Here, in the PSR open area, copper, which is the GND circuit, is exposed, a conductive double-sided tape is attached to the exposed copper, and the conductive double-sided tape is equally attached to the SUS. Thermal compression of COF and SUS brings the COF and SUS into closer contact through a conductive double-sided tape and serves to connect them in a circuit. Through this, SUS acts as a GND circuit and increases the layer. In other words, the existing 2-Layer COF and 1-Layer SUS can produce a 3-Layer effect.

In addition, since the Shield Can is not SMTed to the PCB but welded on top of SUS, the space available for circuit design within the PCB space can be secured by 30% compared to the existing Shield Can SMT. Additionally, rotation issues that occur during the Shield Can Reflow process can be reduced through micro welding. In a structure where COF is not applied (PCB Solder + Shield Can Pick & Place + Reflow), the Can Shift phenomenon may occur depending on the PCB Shield Can Solder Mask tolerance and the Shield Can seating tolerance after reflow. This causes a decrease in yield due to poor performance and poor appearance.

Compared to the above structure, gold plating and reflow processes are eliminated, and by applying airtight welding of SUS plate and shield can of the same material, shielding can be improved + shield can shift, rotation, and void phenomena can be improved.

As described above, according to the application of the Fine Pitch Rule, the capacitor 352 can be mounted along with the MEMS structure 340 and the signal processing element 350 inside the product, as shown in FIG. 44. Through this, noise-related performance such as SNR, PSRR, and PSR can be improved. PCBs other than COF have large Via, Land, Pattern, Clearance, Wire-Bonding Pad Size, and Clearance values, so there is no space to create an SMT Solder Pad that can mount capacitance elements. However, when using a COF board, Figure 45 As shown, the capacitor 352 can be mounted together with the MEMS structure 340 and the signal processing element 350.

When implementing a MEMS microphone of the same size without reducing the size, the internal back-volume can be increased depending on whether COF is applied, and through this, the signal-to-noise ratio (SNR) can be improved.

As shown in Figure 46, Back-Volume can be compared for each case. Figure 46(A) is a case using a Rigid PCB, and Figure 46(B) is a case using COF and SUS and pressed with conductive double-sided tape. D11 is 0.9 mm, D12 is 0.3 mm, and D13 is 0.21. The back-volume for each case is different as shown in Figure 47, and in the case of using COF and SUS, the back-volume increases by 10% compared to the case using rigid PCB. And, even if the capacitor is mounted inside the product, the back-volume increases to about 5%.

As above, as the internal back-volume increases, the signal-to-noise ratio improves to 4% when using COF and SUS compared to the case using rigid PCB, and when the capacitor is mounted inside the product, the signal-to-noise ratio decreases. It improves to the 2% level. PSRR and PSR noise are also improved when a capacitor is installed.

Figure 48 shows a MEMS microphone according to a fourth embodiment of the present invention, and Figures 49 to 54 are diagrams for explaining the MEMS microphone according to a fourth embodiment of the present invention.

The MEMS microphone 400 according to the fourth embodiment of the present invention includes a substrate 410, a housing 420, a MEMS structure 430, and a signal processing element 440.

The substrate 410 is placed at the bottom of the MEMS microphone and has a plate shape. The substrate 410 forms an internal space together with the housing 420. The substrate 410 may include a printed circuit board (PCB), a semiconductor substrate, or a ceramic substrate. The substrate 410 may be composed of a single layer or may be formed by stacking a plurality of substrates.

A hole 431 may be formed in the substrate 410 at a position opposite to the lower part of the MEMS structure 430. The cross-sectional area of the hole 431 may be circular, but is not limited thereto. Here, the hole 431 may be an acoustic hole.

The housing 420 is disposed on the top of the MEMS microphone and has a cover shape that covers the substrate 410. The housing 420 covers the substrate 410 and forms an internal space. The housing 420 may be a can type made of metal or may be made of various materials such as plastic. The housing 420 may be combined with the substrate 410. At this time, the housing 420 may be coupled to the substrate 410 by applying can solder or epoxy, and then hardening the can solder or epoxy.

A MEMS structure 430 and a signal processing element 440 are disposed on the substrate 410. The MEMS structure 430 is disposed within the internal space formed by the substrate 410 and the housing 420. The MEMS structure 430 includes a body, a back plate, and a vibration plate. A hole 431 is formed in the area of the substrate 410 facing the lower part of the MEMS structure 430, and when the diaphragm vibrates due to sound pressure caused by sound flowing in from the outside through the hole 431, the capacitance in the back plate is By measuring, you can sense the acoustic signal. In Figure 48, the back plate is shown as being located on top of the diaphragm, but it is natural that the diaphragm may also be located on top of the back plate.

The signal processing element 440 is disposed on a substrate and is electrically connected to the substrate through a ball grid array (BGA) bond. The signal processing element 440 is electrically connected to the substrate 410 and receives the signal sensed by the MEMS structure 430 through the substrate 410. That is, the MEMS structure 430 and the signal processing element 440 may be electrically connected through the substrate 410. Ball Grid Array (BGA) is a type of surface mount package in which ball-shaped solder 450 is arranged in a grid. A ball grid array is formed on one side of the signal processing element 440, and the substrate 410 ) is installed. At this time, the signal processing element 440 may be in direct contact with the substrate through ball grid array (BGA) bonding. Since the signal processing element 440 is connected to the substrate 410 through a ball grid array bonding, a wire connecting the signal processing element 440 and the substrate 410 is not required. As shown in Figure 49, the wire 460 connecting the MEMS structure 430 and the substrate 410 is connected, but the signal processing element 440 is connected through a ball grid array junction rather than a wire. Since the signal processing element 440 is not connected to a wire, there is no need to apply En-Cap, etc. on the signal processing element 440. In addition, since the signal processing element 440 is directly connected without the first substrate 410, the volume space inside the housing can be increased, the connection through the ball grid array produces less noise than the connection through the wire, and the connection through the ball grid array produces less noise than the connection through the wire. Alternatively, there is more room to utilize the space where En-Caps, etc. are removed, increasing the degree of freedom in design.

The signal processing element 440 receives the signal sensed from the MEMS structure 430 through the substrate 410, which is electrically connected to the ball grid array junction, and the substrate 410 receives the wire 460 from the MEMS structure 430. Signals can be received through. The substrate 410 is connected to the MEMS structure 430 and the wire 460 through wire bonding to receive a signal from the MEMS structure 430, and the signal is transmitted through a circuit pattern inside the substrate 410 to a signal processing element ( 440).

The signal processing element 440 can process the electrical signal sensed and transmitted from the MEMS structure 430. The signal processing element 440 can amplify the signal sensed by the MEMS structure 430. Here, the signal processing element 440 may include, but is not limited to, an application-specific integrated circuit (ASIC). The signal processing element 440 may be formed as a single module. , can be formed in the form of a chip.

The signal processing element 440 includes a first substrate 470 disposed on the upper surface, and the first substrate 410 is disposed on the substrate 410, so that the signal processing element 440 and the substrate 410 are electrically connected to each other. It can be connected to . When electrically connecting the signal processing element 440 and the substrate 410, the first substrate 410 can be used. As shown in Figure 50, the signal processing element 440 is disposed on the first substrate 410, and the first substrate 410 is disposed on the substrate 410, so that the signal processing element 440 and the substrate 410 ) can be electrically connected.

Here, the signal processing element 440 can be bonded to the first substrate 410 using a flip chip method. When attaching a chip to a substrate, flip chip is a method of fusing the chip using the electrode pattern on the bottom of the chip without using additional connection structures such as metal leads (wires) or intermediate media such as ball grid array (BGA). With leadless joining, the joined package is the same size as the chip, which is advantageous for miniaturization and weight reduction, and the distance between electrodes can be made much finer. As shown in FIG. 51, the signal processing element 440 can be placed on the first substrate 410 in a flip chip manner to form a flip chip BGA 500. The flip chip BGA 500 itself can be placed on the substrate 410 by bonding a ball grid array.

The substrate 410 includes a plurality of layers, and the wire 460 and the signal processing element 440 may be electrically connected inside the substrate. The substrate 410 includes a plurality of layers, and the circuit patterns of each layer are electrically connected to each other through vias. The wire 460 may be connected to the substrate 410 in the area between the MEMS structure 430 and the signal processing element 440, as shown in FIGS. 48 and 49. In this case, the MEMS structure 430 and the signal processing element 440 must be spaced apart at a preset interval.

Alternatively, no wire is connected to the signal processing element 440, thereby increasing the freedom of wire wiring of the MEMS structure 430. 52 and 53, the wire 460 may be connected to the substrate 410 at a position corresponding to the side of the signal processing element 440 within a range that does not overlap with the position of the signal processing element 440. In this case, the wire 460 does not need to be connected to the substrate 410 between the MEMS structure 430 and the signal processing element 440, and the MEMS structure 430 and the signal processing element 440 are shown in FIGS. 48 and 48. It can be placed closer than 49.

The hole 432 that transmits sound to the MEMS structure 430 may be formed not in the area of the substrate 410 but in the housing area facing the upper part of the MEMS structure 430. As shown in FIG. 54, a hole 432 may be formed in the housing area facing the upper part of the MEMS structure 430. That is, sound flows in from the top, not the bottom, to generate an electrical signal in the MEMS structure 430, and the signal can be transmitted to the signal processing element 440 through the substrate 410.

The signal processed in the signal processing element 440 may be transmitted externally. At this time, outside

The terminal connected to the outside must be exposed to the outside rather than the inside space, and may be formed on the lower surface of the substrate 410. The signal processing element 440 is formed on a substrate, and a terminal connected to the outside can be formed at the bottom of the substrate, so that signals can be transmitted through a via hole connecting the upper and lower parts of the substrate 410. When the substrate 410 includes a plurality of layers, via holes may be formed to penetrate each layer.

Alternatively, the signal processing element 440 may be embedded within the substrate 410. By embedding the signal processing element 440 inside the substrate 410, the number of elements to be placed in the internal space where the substrate 410 and the housing 420 are formed can be reduced, thereby reducing the overall size, and the signal processing element 440 ) can be reduced with the MEMS structure 430 or the substrate 410, and wire bonding, epoxy application, and drying processes can be eliminated, thereby reducing the process. Additionally, the quality of acoustic sensing can be improved by reducing noise.

It is natural that in addition to the MEMS structure 430 and the signal processing element 440, other elements or modules, such as capacitors, may be disposed in the internal space where the substrate 410 and the housing 420 are formed. Other devices or modules may also be embedded in the substrate 410. When other elements, such as capacitors, are embedded together with the signal processing element 440, they can be embedded so that their positions do not overlap or are concentrated. Alternatively, other elements such as capacitors may be placed on the substrate 410 and only the signal processing element 440 may be embedded.

The substrate 410 may include a first area where the MEMS structure 430 is located and a second area where the housing 420 is placed, and the thickness of the first area is equal to that of the area where the signal processing element 440 is placed. It may be smaller than the thickness. That is, a portion of the substrate 410 may form an empty space and have a cavity structure that is thinner than other portions. Since the MEMS structure 430 has a greater height from the substrate 410 than the signal processing element 440, it greatly affects the overall height of the MEMS microphone. At this time, the height of the MEMS microphone can be reduced by forming a cavity in which the thickness of the substrate 410 in the first area where the MEMS structure 430 is placed is thinner than the area where the signal processing element 440 is placed.

The housing 420 may be coupled to the substrate 410 through can soldering or epoxy. After applying solder, it can be cured to join the housing 420 and the substrate 410.

The modification according to this embodiment may include partial configurations of at least two or more embodiments among a partial configuration of the first embodiment, a partial configuration of the second embodiment, a partial configuration of the third embodiment, and a partial configuration of the fourth embodiment. . That is, the modified example includes one of the first to fourth embodiments, but omits some components of the corresponding embodiment and includes some components of at least one embodiment other than the corresponding embodiment. can do.

Those skilled in the art related to this embodiment will understand that the above-described base material can be implemented in a modified form without departing from the essential characteristics. Therefore, the disclosed methods should be considered from an explanatory rather than a restrictive perspective. The scope of the present invention is indicated in the claims rather than the foregoing description, and all differences within the equivalent scope should be construed as being included in the present invention.

Claims (10)

Board;
a housing covering the substrate;
a MEMS structure disposed on the substrate; and
Comprising a signal processing element disposed on the substrate and spaced apart from the MEMS structure,
The signal processing element is a MEMS microphone electrically connected to the substrate through a ball grid array (BGA) junction. According to paragraph 1,
It includes a first substrate on which the signal processing element is disposed,
The first substrate is disposed on the substrate, and the signal processing element and the substrate are electrically connected to each other. According to paragraph 2,
The signal processing element is a MEMS microphone bonded to the first substrate using a flip chip method. According to paragraph 1,
The signal processing element is a MEMS microphone that is in direct contact with the substrate through ball grid array (BGA) bonding. According to clause 4,
Includes a wire electrically connecting the MEMS structure and the substrate,
The signal processing element is,
A MEMS microphone electrically connected to the MEMS structure through the substrate and wire. According to clause 5,
The substrate includes a plurality of layers,
A MEMS microphone in which the wire and the signal processing element are electrically connected inside the substrate. According to paragraph 1,
A MEMS microphone in which a hole is formed in a substrate area facing the lower part of the MEMS structure. According to paragraph 1,
A MEMS microphone in which a hole is formed in a housing area facing the upper part of the MEMS structure. According to paragraph 1,
The signal processing element is a MEMS microphone embedded in the substrate. According to clause 9,
A MEMS microphone including a capacitor embedded in the substrate.