Microphone assembly, circuit board, circuit board array, and method for manufacturing circuit board

Abstract

The present invention relates to a microphone assembly, a circuit board, a circuit board array, and a method for manufacturing a circuit board. The microphone assembly includes: an acoustic transducer that generates an electrical signal in response to acoustic activity; and an integrated circuit that is electrically coupled to the acoustic transducer and receives the electrical signal from the acoustic transducer and generates an output signal representative of the acoustic activity. The microphone assembly also includes: a substrate that includes a first surface on which the integrated circuit is mounted; a guard ring that is mounted on the substrate and elevated relative to the first surface of the substrate; and a cover that is mounted to the guard ring, wherein the cover, the guard ring, and the substrate form a housing in which the transducer and the integrated circuit are disposed.

Description

Technical Field

[0001] The present invention relates to a microphone assembly, a circuit board and a circuit board array. Background Art

[0002] Microphone assemblies are used in a variety of applications, such as mobile phones and recording devices, to record acoustic signals. Microphone assemblies may include encapsulation material over the components of the microphone assembly. The encapsulation material may flow onto the bonding surface and reduce the bond strength between the can and the bonding surface. Summary of the Invention

[0003] One aspect of the present invention relates to a microphone assembly, comprising: an acoustic transducer configured to generate an electrical signal in response to acoustic activity; an integrated circuit electrically coupled to the acoustic transducer and configured to receive the electrical signal from the acoustic transducer and generate an output signal representative of the acoustic activity; a substrate comprising a first surface on which the integrated circuit is mounted; a protective ring mounted on the substrate and elevated relative to the first surface of the substrate; and a cover mounted to the protective ring, wherein the cover, the protective ring, and the substrate form a housing in which the acoustic transducer and the integrated circuit are disposed.

[0004] Another aspect of the present invention relates to a circuit board for a microphone assembly, the circuit board comprising: a substrate including a first surface; and a guard ring mounted on the substrate and elevated relative to the first surface of the substrate.

[0005] Yet another aspect of the present invention relates to a circuit board array, comprising a plurality of the above-mentioned circuit boards.

[0006] Another aspect of the present invention relates to a method for manufacturing a circuit board for a microphone assembly, the method comprising the steps of: forming a substrate array; forming electrical traces in or on the substrates; connecting surface mount contacts on the surface of each substrate of the substrate array to electrical interfaces or bonding pads on the opposite surface of each substrate of the substrate array; and forming a guard ring on the surface of each substrate, wherein the guard ring is elevated relative to the surface of the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The foregoing and other features of the present invention will become more fully apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings. These drawings merely depict several embodiments according to the present invention and, therefore, should not be construed as limiting the scope of the present invention. Various embodiments are described in more detail below in conjunction with the accompanying drawings.

[0008] Figure 1 is a partial cross-sectional view of the microphone assembly.

[0009] Figure 2 This is an example diagram of a circuit board.

[0010] Figure 3 is a partial cross-sectional view of a substrate during a manufacturing step.

[0011] Figure 4 is a partial cross-sectional view of a substrate during another fabrication step.

[0012] Figure 5 is a partial cross-sectional view of a substrate during yet another manufacturing step.

[0013] Figure 6 is an illustrative diagram of a method for manufacturing a circuit board. DETAILED DESCRIPTION

[0014] Disclosed herein are apparatus and methods for providing a protective ring for a microphone assembly. Specifically, the microphone assembly disclosed herein includes a protective ring on a surface of a substrate, formed during the manufacture of the microphone assembly. The protective ring defines a bonding surface for coupling to a cover. The bonding surface is elevated relative to the surface of the substrate. The protective ring can restrict the flow of encapsulation material onto the bonding surface.

[0015] During production, multiple microphone assemblies can be formed into an array. In some embodiments, the guard rings for each microphone assembly in the array can be manufactured during a single manufacturing step. The guard rings can be integrally formed with the substrate, or can be formed separately from the substrate and coupled to the substrate.

[0016] Among other advantages, the elevation of the surface of the guard ring relative to the surface of the substrate limits the flow of encapsulation material onto the surface of the guard ring. The integrity of the guard ring surface is maintained throughout the manufacturing process. Figures 1 to 6 to more fully explain the details of the general description provided above.

[0017] Now refer to Figure 1, shows a cross-sectional view of a microphone assembly 10. The microphone assembly 10 is configured to sense acoustic activity (e.g., sound waves, etc.) and generate an electrical signal in response to the acoustic activity. The microphone assembly 10 is configured to be installed in a device (e.g., a mobile phone, a camera, a recorder, etc.). The microphone assembly 10 includes an acoustic transducer 12, which is configured to generate an electrical signal in response to the acoustic activity. In some embodiments, the acoustic transducer 12 is a microelectromechanical system (MEMS) transducer. In some implementations, the acoustic transducer 12 is a capacitive transducer, which includes one or more backplates and one or more diaphragms, wherein the one or more diaphragms are configured to move relative to the one or more backplates to generate a variable capacitance indicative of the sensed acoustic activity that causes the movement of the diaphragm. The microphone assembly 10 also includes an integrated circuit 14. The integrated circuit 14 is configured to receive the electrical signal from the acoustic transducer 12 and generate an output signal representing the acoustic activity. In some embodiments, the integrated circuit 14 is an application-specific integrated circuit (ASIC). Microphone assembly 10 also includes a substrate (shown as substrate 16). In some embodiments, substrate 16 is a printed circuit board. In some embodiments, acoustic transducer 12 and integrated circuit 14 are coupled to substrate 16. Microphone assembly 10 also includes a cover 18. In some embodiments, acoustic transducer 12 and / or integrated circuit 14 are coupled to cover 18. In some embodiments, cover 18 is a hood (such as a metal hood). Cover 18 is configured to define a housing between cover 18 and substrate 16.

[0018] In some embodiments, the substrate 16 defines a port 20 formed through the substrate 16. In other embodiments, the cover 18 defines a port that extends through the cover 18. The port 20 is configured to provide a path for acoustic signals to pass through the substrate 16 or the cover 18 and contact the acoustic transducer 12. The acoustic transducer 12 and the integrated circuit 14 are electrically coupled via wires 22. The wires 22 transmit signals from the acoustic transducer 12 to the integrated circuit 14. The integrated circuit 14 is electrically coupled to contacts on the substrate 16 via the wires 24. Signals can be transmitted to devices external to the microphone assembly 10 via contacts on the substrate 16 (e.g., contacts formed on an outer surface of the substrate 16 that are electrically coupled to contacts to which the wires 24 are connected).

[0019] Microphone assembly 10 also includes a guard ring 26. Guard ring 26 is coupled to a mounting surface on the periphery of substrate 16 and defines a first guard ring surface 28 (e.g., a bonding surface, attachment surface, coupling surface, etc.). In some embodiments, guard ring 26 is coupled to bonding pads on substrate 16. The periphery of substrate 16 is defined such that acoustic transducer 12 and integrated circuit 14 are located within the periphery. In some embodiments, guard ring 26 is formed separate from substrate 16 and coupled to the mounting surface of substrate 16. Guard ring 26 defines a second guard ring surface. First guard ring surface 28 is opposite second guard ring surface. Second guard ring surface is coupled to the mounting surface of substrate 16. In other embodiments, guard ring 26 and substrate 16 are formed as a unitary structure. First guard ring surface 28 of guard ring 26 is elevated relative to the mounting surface of the substrate. Microphone assembly 10 includes encapsulation material 30. Encapsulation material 30 covers at least one of wires 22, wires 24, or integrated circuit 14. Encapsulation material 30 isolates the components, thereby maintaining their electrical connection and / or integrity.

[0020] First guard ring surface 28 is elevated relative to the mounting surface of substrate 16, defining a cavity within which encapsulation material 30 is disposed. First guard ring 26 restricts the flow of encapsulation material 30 from the cavity. In some embodiments, encapsulation material 30 is liquid upon entering the cavity and hardens over time. First guard ring surface 28 is restricted from contact with encapsulation material 30.

[0021] Figure 2 is an illustrative diagram of a circuit board 100. The circuit board 100 can be used in the microphone assembly 10. The circuit board 100 can include one or more layers to define the substrate 16. The circuit board 100 also includes a guard ring 26. The guard ring 26 can be formed integrally with the substrate 16 or formed separately from the substrate 16 and coupled to a surface of the substrate 16. The circuit board 100 also includes an electrical trace 118. In some embodiments, the electrical trace 118 is disposed on the surface of the substrate 16. In other embodiments, the electrical trace 118 is disposed below the surface of the substrate 16. In this embodiment, an aperture 120 is formed in the substrate 16 to facilitate access to the electrical trace 118. The electrical trace 118 extends through the substrate 16 to interface with an opposite side of the substrate 16.

[0022] Figure 31 is a partial view of a circuit board 100 at a step in a manufacturing process. In the illustrated embodiment, substrate 16 includes a first layer 102, a second layer 104, and a third layer 106. First layer 102 defines a first surface 108 (e.g., an attachment surface, etc.). In some embodiments, first layer 102 is made of a conductive material. Second layer 104 is coupled to first surface 108 of first layer 102. Second layer 104 defines a second surface 110. Second surface 110 can be a connection surface for acoustic transducer 12 and / or integrated circuit 14. In some embodiments, second layer 104 is made of a non-conductive material (such as a solder mask material). Third layer 106 is opposite first layer 102 on circuit board 100. In some embodiments, third layer 106 is made of a conductive material. In some embodiments, circuit board 100 further includes a dry film layer 112. Dry film layer 112 is disposed between first layer 102 and third layer 106. The dry film layer 112 may be configured to transmit electrical signals between the first layer 102 and the third layer 106. The dry film layer 112 may also be configured to limit the transmission of electrical signals between the first layer 102 and the third layer 106.

[0023] A dry film layer 112 is coupled to the first surface 108 and the second surface 110. The dry film layer 112 defines a cavity 114. The cavity 114 extends around the perimeter of the substrate 16. In some embodiments, the cavity 114 has a rectangular cross-section. In other embodiments, the cavity 114 has a trapezoidal cross-section. The dry film layer 112 covers a portion of the first layer 102 and defines the coupling surface 108 as the uncovered portion of the first layer 102.

[0024] Figure 4 FIG2 is a partial view of circuit board 100 during a subsequent manufacturing step. Material is deposited in cavity 114, defined by dry film layer 112 and coupled to coupling surface 108. The material is molded to the cross-sectional shape of cavity 114 to define guard ring 26. The material may be copper, epoxy, silicone, or another material. In some embodiments, guard ring 26 is formed separately from substrate 16 and coupled to coupling surface 108 of substrate 16 to form circuit board 100.

[0025] Figure 5 1 is a partial view of the circuit board 100 at a subsequent manufacturing step. The dry film layer 112 is removed from the substrate 16. A fourth surface 28 (eg, a bonding surface, etc.) is defined on the guard ring 26. The fourth surface 28 is elevated relative to the first surface 108 and the second surface 110.

[0026] Figure 6Depicted is a method 200 of manufacturing a circuit board 100 for use with a microphone assembly 10. The method 200 is merely illustrative, and in other implementations, some steps of the method 200 may be performed in a different order and / or fewer or additional steps may be used without departing from the scope of the present invention.

[0027] At step 202, an array of substrates 16 is formed. The array includes two or more substrates 16. Each substrate 16 in the array includes a first layer 102, a second layer 104, and a third layer 106.

[0028] At step 204, electrical traces 118 are formed in or on each substrate 16 of the array. In some embodiments, the electrical traces 118 are disposed on the first layer 102. In other embodiments, the electrical traces 118 are disposed on the second layer 104. The electrical traces 118 can interface with components external to the microphone assembly 10.

[0029] At step 206, the surface mount contacts on the first surface 108 are connected to electrical interfaces or bond pads on the third layer 106. The connection between the surface mount contacts and the electrical interfaces or bond pads may be a wire or another conductive material extending between the first surface 108 and the third layer 106.

[0030] At step 208, a guard ring 26 is formed on the first surface 108 of each substrate 16 of the array. The guard ring 26 defines a bonding surface 28 that is elevated relative to the first surface 108. In some embodiments, the guard ring 26 is formed as a unitary structure with the substrate 16. In this embodiment, the first surface 108 can be provided with a dry film layer 112 to define a cavity 114. The cavity 114 is filled with a guard ring material (e.g., copper, etc.). The dry film layer 112 is removed to define the guard ring 26. In other embodiments, the guard ring 26 is a separate component of the substrate 16 and is coupled to the first surface 108 of each substrate 16.

[0031] At step 210, individual circuit boards 100 are removed from the array to define a single circuit board 100. In some embodiments, a second dry film layer is formed on the first surface 108. The second dry film layer defines a removal portion where the first circuit board 100 is removed from the second circuit board 100 of the array of circuit boards 100.

[0032] A first aspect of the present invention relates to a microphone assembly. The microphone assembly includes an acoustic transducer that generates an electrical signal in response to acoustic activity, and an integrated circuit that is electrically coupled to the acoustic transducer and receives the electrical signal from the acoustic transducer and generates an output signal representative of the acoustic activity. The microphone assembly also includes a substrate that includes a first surface on which the integrated circuit is mounted, a guard ring that is mounted on the substrate and elevated relative to the first surface of the substrate, and a cover that is mounted to the guard ring, wherein the cover, guard ring, and substrate form a housing in which the transducer and integrated circuit are disposed.

[0033] A second aspect of the present invention relates to a circuit board for a microphone assembly. The circuit board includes a substrate. The substrate includes a first surface. The circuit board also includes a guard ring mounted on the substrate and elevated relative to the first surface of the substrate.

[0034] A third aspect of the present invention relates to a method for manufacturing a circuit board for a microphone assembly. The method includes the following steps: forming an array of substrates; forming electrical traces in or on the substrates; and connecting surface mount contacts on a surface of each substrate in the array to electrical interfaces or bonding pads on an opposite surface of each substrate in the array. The method also includes the following steps: forming a guard ring on a surface of each substrate in the array, wherein the guard ring is elevated relative to the surface of the substrate.

[0035] The subject matter described herein sometimes illustrates different components contained within or connected to different other components. It will be understood that the architectures depicted in this manner are merely exemplary, and in fact, many other architectures that achieve the same functionality can be implemented. In a conceptual sense, any arrangement of components for achieving the same functionality is effectively "associated" so as to achieve the desired functionality. Thus, any two components combined herein to achieve a specific functionality can be considered to be "associated" with each other so as to achieve the desired functionality, regardless of the architecture or intermediate components. Similarly, any two components associated in this manner can also be considered to be "connected in operation" or "coupled in operation" to achieve the desired functionality, and any two components that can be associated in this manner can also be considered to be "coupled in operation" to achieve the desired functionality. Specific examples of being coupled in operation include, but are not limited to, components that can physically cooperate and / or physically interact and / or components that can wirelessly interact and / or wirelessly interact and / or components that logically interact and / or logically interact.

[0036] Regarding the use of plural and / or singular terms herein, those skilled in the art can translate from plural to singular and / or from singular to plural when appropriate, depending on the context and / or application. For clarity, various singular / plural permutations may be explicitly set forth herein.

[0037] Those skilled in the art will understand that, generally, the terms used herein, and especially in the appended claims (e.g., the bodies of the appended claims), are generally intended to be “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “comprising” should be interpreted as “including but not limited to,” etc.).

[0038] Although the drawings and description may illustrate a particular order of method steps, unless otherwise specified above, the order of these steps may differ from the steps depicted and described. In addition, unless otherwise specified above, two or more steps may be performed simultaneously or partially simultaneously. Such variations may, for example, depend on the software and hardware systems selected and the designer's choice. All of these variations are within the scope of the present invention. Similarly, software implementations of the described methods may be accomplished using standard programming techniques with rule-based logic and other logic to complete the various connection steps, processing steps, comparison steps, and decision steps.

[0039] Those skilled in the art will further understand that if a specific number of a recited claim is intended, such intent will be explicitly stated in the claim, and in the absence of such a statement, no such intent exists. For example, to aid understanding, the following appended claims may contain the use of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of these phrases should not be interpreted as implying that the reference of a claim recited by the indefinite article "a" or "an" will limit any particular claim containing such a recited claim recitation to an invention containing only one such recitation, even if the same claim includes the introductory phrases "one or more" or "at least one" and an indefinite article such as "a" or "an" (e.g., "a" and / or "an" should generally be interpreted to mean "at least one" or "one or more"); the same is true for the use of definite articles used to refer to claim recitations. In addition, even if a specific number of a recited claim recitation is explicitly stated, those skilled in the art will recognize that such a recitation should generally be interpreted to mean at least the recited number (e.g., a detailed recitation of "two recitations" without other modifiers generally means at least two recitations, or two or more recitations).

[0040] Furthermore, in those instances where a convention similar to “at least one of A, B, and C, etc.” is used, generally speaking, such construction is intended in the sense that one skilled in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include, but is not limited to, systems having A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). In those instances where a convention similar to “at least one of A, B, or C, etc.” is used, generally speaking, such construction is intended in the sense that one skilled in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include, but is not limited to, systems having A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). One skilled in the art would further understand that any disjunctive words and / or phrases that actually present two or more alternative terms, whether in the specification, claims, or drawings, should be understood to contemplate the possibility of including one, either, or both of the terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

[0041] Furthermore, use of the words "approximately," "about," "approximately," "substantially," etc., means plus or minus ten percent unless otherwise indicated.

[0042] The foregoing description of the exemplary embodiments has been presented for purposes of illustration and description. It is not intended to be exhaustive or limited to the precise forms disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the disclosed embodiments. It is intended that the scope of the invention be defined by the following claims and their equivalents.

Claims

1. A microphone assembly, comprising: an acoustic transducer configured to generate an electrical signal in response to acoustic activity; an integrated circuit electrically coupled to the acoustic transducer and configured to receive the electrical signal from the acoustic transducer and generate an output signal representative of the acoustic activity; a substrate comprising a first surface, the integrated circuit being mounted on the first surface; an encapsulation material at least partially covering the integrated circuit; a guard ring mounted on the substrate and elevated relative to the first surface of the substrate; an electrical interface on a second surface of the substrate opposite the first surface, the integrated circuit being electrically coupled to contacts of the electrical interface; as well as a cover mounted to the protective ring, wherein the cover and the substrate form a housing in which the acoustic transducer and the integrated circuit are disposed, The protective ring defines a barrier on the substrate to limit the packaging material from flowing out of the housing.

2. The microphone assembly according to claim 1, wherein The guard ring and the substrate are separate components.

3. The microphone assembly according to claim 1, wherein The guard ring and the substrate are an integral structure.

4. The microphone assembly according to claim 1, wherein The microphone assembly also includes an integrated circuit interface, which is defined on the perimeter of the substrate by one or more wire bonding pads or a surface mount interface, wherein the guard ring on the first surface is connected to the integrated circuit interface and the guard ring second surface is defined to be opposite to the guard ring first surface.

5. The microphone assembly according to claim 1, wherein The housing includes an acoustic port, and the acoustic transducer is located above the acoustic port.

6. A circuit board for a microphone assembly, the circuit board comprising: a substrate comprising a first surface; an electrical interface comprising at least one surface mount electrical contact on a second surface of the substrate opposite the first surface; as well as a protective ring mounted on the substrate and elevated relative to the first surface of the substrate, wherein the protective ring is disposed around a perimeter of the circuit board and defines a perimeter wall that restricts encapsulation material from flowing onto a surface of the protective ring, the surface of the protective ring being elevated relative to the first surface.

7. The circuit board of claim 6, further comprising an electrical trace disposed in or on the substrate and electrically connecting the at least one surface mount electrical contact to the electrical interface on the first surface.

8. The circuit board according to claim 6, wherein The guard ring and the substrate are separate components.

9. The circuit board according to claim 6, wherein: The substrate and the guard ring are an integral structure. 10 . A circuit board array comprising a plurality of circuit boards according to claim 6 .

11. A method for manufacturing a circuit board for a microphone assembly, the method comprising the steps of: forming a substrate array; forming electrical traces in or on the substrate; connecting surface mount contacts on a surface of each substrate of the substrate array to electrical interfaces on an opposite surface of each substrate of the substrate array; as well as forming a guard ring on the surface of each of the substrates, wherein the guard ring is elevated relative to the surface of the substrate, and The protection ring limits the packaging material from flowing onto the surface of the protection ring, and the surface of the protection ring is elevated relative to the surface of the substrate.

12. The method according to claim 11, further comprising the steps of: The surface of each of the substrates is provided with a dry film layer, the dry film layer forming a recess extending around the perimeter of the substrate.

13. The method according to claim 12, further comprising the steps of: The recess is filled with a guard ring material to form the guard ring.

14. The method according to claim 13, wherein The guard ring material is copper.

15. The method according to claim 13, further comprising the steps of: The dry film layer is removed from the substrate and leaves the guard ring material.

16. The method according to claim 15, further comprising the steps of: Individual substrates are removed from the array of substrates.

17. The method according to claim 11, further comprising the steps of: A preformed guard ring is coupled to the surface of each of the substrates.

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