Electromagnetic acoustic module, lead frame structure and manufacturing method

Abstract

The application provides an electromagnetic acoustic module, a lead frame structure and a manufacturing method, relates to the technical field of microelectronic devices, and the electromagnetic acoustic module comprises a packaging base, a lead frame embedded in the packaging base, a chip arranged on a chip bearing part, a coil support and a coil arranged on a first surface, a magnetic circuit system and a vibration system arranged on a side of the coil support away from the packaging base, and an upper cover surrounding the packaging base to form an acoustic cavity. The chip bearing part is located in a side area of the module plane, and in a plane perpendicular to the thickness direction of the packaging base, the orthographic projection of the chip bearing part and the orthographic projection of the coil support are separated from each other. In this way, the chip package and the magnetic circuit system and the vibration system can be prevented from being stacked in series in the thickness direction of the module, thereby providing a structural basis for low profile of the module, effectively improving product size precision, vibration system resonance frequency consistency, reducing manual adjustment and processes, and reducing costs compared with the existing production method.

Description

Technical Field

[0001] This application relates to the field of microelectronic device technology, and more specifically, to an electromagnetic acoustic module, a lead frame structure, and a manufacturing method thereof. Background Technology

[0002] As smart wearable devices, portable medical devices, and miniature consumer electronics products strive for extreme thinness and lightness, more stringent requirements are being placed on the dimensions of their internal core components, especially their cross-sectional height. In the field of electromagnetic acoustic modules, to improve system integration and overall performance, the use of System-in-Package (SiP) technology to directly integrate the driver chip inside the acoustic module has become an important direction for technological evolution.

[0003] In existing integrated acoustic module designs, to achieve structural symmetry and uniform wiring layout, the driver chip is often placed in the geometric center of the package substrate. This conventional layout inevitably leads to a structural conflict: the centrally located chip and its external encapsulation material occupy valuable vertical space in the module's central area, forcing the acoustic module's coil support, magnetic circuit system, and vibration system to be stacked directly above the chip package. This series-stacked structure along the module's thickness squeezes the available space for the upper magnetic circuit system and acoustic cavity. To ensure sufficient electroacoustic performance, the overall module thickness must increase; forcibly compressing the height will result in performance degradation due to the sacrifice of magnetic circuit volume and cavity volume.

[0004] Therefore, under the premise of integrating the driver chip into the electromagnetic acoustic module, how to avoid the series stacking of the chip package and the magnetic circuit / vibration system in the thickness direction of the module in order to achieve the low profile of the module has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this application provides an electromagnetic acoustic module, a lead frame structure, and a manufacturing method.

[0006] In a first aspect, this application provides an electromagnetic acoustic module, comprising:

[0007] The encapsulation substrate has a first surface and a second surface disposed opposite to each other, and a side surface connecting the first surface and the second surface;

[0008] A lead frame is embedded in the package substrate, and the lead frame includes a chip carrier, an external pin portion, and a coil connection portion;

[0009] A chip is disposed on the chip carrier and encapsulated by the packaging substrate. The chip is electrically connected to the external pin portion and the coil connection portion respectively through bonding wires.

[0010] A coil support is disposed on the first surface;

[0011] A coil is mounted on the coil support, and the lead end of the coil is electrically connected to the coil connection part;

[0012] A magnetic circuit system and a vibration system are disposed on the side of the coil support away from the packaging substrate, with the magnetic circuit system located between the coil support and the vibration system;

[0013] The top cover is disposed on one side of the first surface and forms an acoustic cavity with the encapsulation substrate;

[0014] In a plane perpendicular to the thickness direction of the packaging substrate, the orthographic projection of the chip carrier and the orthographic projection of the coil support are separate from each other.

[0015] Optionally, the coil connection portion includes a first open-window welding area and a second open-window welding area that are spaced apart from each other. The first open-window welding area and the second open-window welding area are welding areas recessed into the first surface of the coil connection portion. The two lead ends of the coil are spot welded to the first open-window welding area and the second open-window welding area, respectively.

[0016] Optionally, the chip carrier includes a carrier platform, and the carrier platform and the rest of the lead frame have a height difference in the thickness direction of the lead frame.

[0017] Optionally, the magnetic circuit system includes a ring magnet, and the vibration system includes a vibrating diaphragm, with the ring magnet located between the coil support and the vibrating diaphragm.

[0018] Optionally, the packaging substrate is formed of a molding material that covers the chip, the bonding wires connected to the chip, and the portion of the lead frame located between the external pin portion and the coil connection portion, and exposes the end of the external pin portion on the side surface of the packaging substrate, such that the first windowed soldering area and the second windowed soldering area are recessed into the first surface.

[0019] Secondly, this application provides a lead frame structure applied to the electromagnetic acoustic module in the first aspect above, or any possible implementation of the first aspect, comprising:

[0020] The frame body and multiple unit regions connected by the frame body are arranged in an array on the frame body. Each unit region includes a chip carrier, an external pin, a coil connection, and a connection support connecting the above parts.

[0021] In this configuration, within a plane perpendicular to the thickness direction of the lead frame, the chip carrier is located at one edge of the corresponding unit region, and the coil connection is spaced apart from the chip carrier.

[0022] Optionally, the chip carrier includes a carrier platform formed by a semi-etching process, the carrier platform having a stepped structure.

[0023] Optionally, the connecting support is provided with cutting alignment marks and / or thinning grooves, and a cutting channel is provided between two adjacent unit areas.

[0024] Thirdly, this application provides a method for manufacturing an electromagnetic acoustic module, comprising:

[0025] An array-type lead frame is provided, the array-type lead frame includes multiple unit regions, and a cutting channel is provided between two adjacent unit regions. Each unit region has a chip carrier, an external pin, and a coil connection. The chip carrier is located on one side edge of the corresponding unit region, and the coil connection is spaced apart from the chip carrier.

[0026] The chip is fixed to the chip carrier, and the chip is connected to the external pin portion and the coil connection portion respectively by bonding wires;

[0027] The chip, the bonding wire, and the lead frame located between the external pin portion and the coil connection portion are molded and packaged to form a package substrate having a first surface, a second surface, and a side surface. The coil connection portion is formed into a window-type soldering area recessed in the first surface, so that the end of the external pin portion is exposed on the side surface.

[0028] The array-type lead frame is divided along the cutting path to form multiple individual units;

[0029] The coil support with the coil is fixed to the first surface of the unit, and the lead end of the coil is electrically connected to the coil connection part;

[0030] The magnetic circuit system and the vibration system are assembled on the side of the coil support away from the packaging substrate;

[0031] And fixing the top cover to one side of the first surface of the encapsulation substrate to form the electromagnetic acoustic module in the first aspect, or any possible implementation of the first aspect.

[0032] Optionally, fixing the chip to the chip carrier includes: attaching the chip to the chip carrier using an adhesive material.

[0033] Optionally, electrically connecting the lead end of the coil to the coil connection part includes: welding the lead end of the coil to the open-window welding area of ​​the coil connection part by spot welding.

[0034] Optionally, before spot welding the lead end of the coil to the open-window welding area of ​​the coil connection, the method further includes:

[0035] Acquire a surface image of the first surface of the monomer;

[0036] The boundary contour of the windowed welding area of ​​the coil connection is determined based on the surface image; the position data of the bonding wire recorded before the molding encapsulation is obtained, and the projection boundary of the area where the bonding wire is located in the plane perpendicular to the thickness direction of the encapsulation substrate is determined based on the position data.

[0037] Multiple candidate spot welding positions are generated within the window-type welding zone.

[0038] Optional, also includes:

[0039] For each of the candidate spot welding positions, calculate the first distance from the candidate spot welding position to the projected boundary and the second distance to the boundary profile;

[0040] Select the target spot welding position from the candidate spot welding positions where the first distance is greater than the first preset threshold and the second distance is greater than the second preset threshold.

[0041] Optionally, generating multiple candidate spot weld locations within the window-type welding zone includes:

[0042] Obtain the local curvature of each boundary point on the boundary profile;

[0043] Boundary points with local curvature greater than the curvature threshold and their regions within a preset range are marked as boundary anomaly regions.

[0044] The candidate spot weld location is generated in the area outside the boundary abnormal region of the windowed welding zone.

[0045] Compared to existing technologies, the electromagnetic acoustic module provided in this application separates the chip carrier portion of the lead frame from the coil support in a plane perpendicular to the thickness direction of the package substrate. This allows the chip and the package substrate encapsulating the chip to be staggered from components such as the coil support and magnetic circuit system in the thickness direction. This structure avoids the series stacking of semiconductor chips and acoustic driving components in the thickness direction of integrated acoustic devices. Since there is no need to avoid the chip below the coil support and magnetic circuit system, these acoustic components can make full use of the vertical space not occupied by the chip.

[0046] Therefore, without reducing the volume of the magnetic circuit system and the acoustic cavity volume, the technical solution of this application effectively reduces the overall thickness of the electromagnetic acoustic module, achieving a low-profile design. Simultaneously, this structure improves the internal space utilization of the module, which is beneficial for meeting the requirements of microelectronic devices for high integration and thinness of components. Compared with existing LCP material injection molding production, the chip packaging method in this application can improve the product dimensional accuracy from ±0.01mm to ±0.005mm, improve the consistency of the resonant frequency of the vibration system, reduce manual adjustment, and also reduce processes and lower costs. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the structure of the lead frame unit region in one embodiment of this application;

[0048] Figure 2 This is a schematic diagram of the lead frame array in one embodiment of this application;

[0049] Figure 3 This is a schematic diagram of the lead frame unit structure after chip mounting and bonding in one embodiment of this application;

[0050] Figure 4 This is a schematic diagram of the encapsulation substrate structure after molding and encapsulation in one embodiment of this application;

[0051] Figure 5 This is an exploded structural diagram of an electromagnetic acoustic module in one embodiment of this application;

[0052] Figure 6 This is a schematic cross-sectional view of the assembly of an electromagnetic acoustic module in one embodiment of this application;

[0053] Figure 7 This is a schematic diagram showing the chip package, magnetic circuit system, and vibration system stacked in series along the thickness direction in an existing integrated solution.

[0054] Figure 8 A flowchart illustrating a manufacturing method provided in an embodiment of this application.

[0055] Figure descriptions: 1. Unit area; 2. Chip carrier; 3. External pin portion; 4. Coil connection portion; 411. First window-type soldering area; 412. Second window-type soldering area; 5. Connection support portion; 6. Cutting channel; 7. Thinning groove; 8. Chip; 9. Bonding wire; 10. Packaging substrate; 11. Coil bracket; 12. Coil; 13. Circular magnet; 14. Vibrating diaphragm; 15. Top cover; 16. Acoustic cavity. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. Where there is no conflict, the embodiments and features described herein can be combined with each other.

[0057] It should be noted that when an element is referred to as "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," "up," "down," and similar expressions used in this embodiment are for illustrative purposes only and do not represent the only implementation.

[0058] In one embodiment, such as Figures 3 to 6 As shown, the electromagnetic acoustic module includes a package substrate 10, a lead frame embedded in the package substrate 10, a chip 8 disposed on the chip carrier 2 of the lead frame, a coil support 11 disposed on the first surface of the package substrate 10 and a coil 12 disposed on the coil support 11, a magnetic circuit system and a vibration system disposed on the side of the coil support 11 away from the package substrate 10, and a top cover 15 disposed on one side of the first surface and forming an acoustic cavity 16 with the package substrate 10.

[0059] Specifically, the encapsulation substrate 10 may be formed of a molding material and has a first surface and a second surface disposed opposite to each other, as well as a side surface connecting the first surface and the second surface. The first surface may serve as the mounting side for the coil support 11, the magnetic circuit system, the vibration system, and the top cover 15. The second surface is disposed opposite to the first surface, and the side surface is used to form the end exposure area of ​​the external lead portion 3. A lead frame is embedded inside the encapsulation substrate 10, and the lead frame includes at least a chip carrier portion 2, an external lead portion 3, and a coil connection portion 4. The chip 8 is disposed on the chip carrier portion 2 and encapsulated by the encapsulation substrate 10. The chip 8 is electrically connected to the external lead portion 3 and the coil connection portion 4 respectively through bonding wires 9, thereby establishing an internal electrical connection path between the chip 8 and the external circuit and the coil 12.

[0060] In this embodiment, the coil support 11 is disposed on the first surface of the encapsulation substrate 10, the coil 12 is disposed on the coil support 11, and the lead end of the coil 12 is electrically connected to the coil connection part 4.

[0061] As an alternative, the coil connection portion 4 includes a welding area recessed in the first surface for welding connection with the lead end of the coil 12;

[0062] As an alternative, the welding area may include a first open-window welding area 411 and a second open-window welding area 412 that are spaced apart from each other, and the two leads of the coil 12 are spot welded to the corresponding welding areas respectively.

[0063] Therefore, the drive signal output by chip 8 can be transmitted to coil 12 via bonding wire 9 and coil connection part 4 to drive the subsequent magnetic circuit system and vibration system to work.

[0064] Furthermore, the magnetic circuit system and vibration system are disposed on the side of the coil support 11 opposite to the packaging substrate 10. Figure 5 and Figure 6 In the illustrated embodiment, the magnetic circuit system may include a circular magnet 13, and the vibration system may include a vibrating diaphragm 14. The circular magnet 13 is located between the coil support 11 and the vibrating diaphragm 14. The top cover 15 is disposed on one side of the first surface and together with the encapsulation substrate 10 forms an acoustic cavity 16. Thus, the coil support 11, coil 12, circular magnet 13, vibrating diaphragm 14, and top cover 15 form an electromagnetic drive and vibration sound generation structure that is sequentially fitted along the thickness direction on the encapsulation substrate 10.

[0065] The key to this embodiment is that, in a plane perpendicular to the thickness direction of the packaging substrate 10, the orthographic projection of the chip carrier 2 and the orthographic projection of the coil support 11 are separate from each other. In other words, the chip carrier 2 is not located in the central mounting area corresponding to the coil support 11, but is offset from the coil support 11 in planar layout.

[0066] In one example, the chip carrier 2 can be located on one edge of the corresponding unit area or module plane, allowing the coil support 11, magnetic circuit system, and vibration system to be arranged in the central area not occupied by the chip 8. This planar staggered layout avoids the chip 8 and its packaged portion from forming a series stack with the magnetic circuit system and vibration system in the module thickness direction, which helps to reserve more sufficient mounting height for the magnetic circuit system and vibration system, and provides more reasonable spatial conditions for the formation of the acoustic cavity 16, thereby achieving a low profile of the electromagnetic acoustic module.

[0067] Meanwhile, the packaging substrate 10 not only encapsulates the chip 8 and bonding wires 9, but also serves as the assembly base for the coil support 11, magnetic circuit system, vibration system, and top cover 15. Therefore, on the one hand, it enables the integration of chip 8 packaging, internal electrical connection leads, and acoustic drive structure within the same module; on the other hand, it helps to shorten the internal connection path between chip 8 and coil 12, and reduces the thickness and assembly complexity associated with implementing electrical connections through independent circuit boards or intermediate connectors. Figure 7 As can be understood from the conventional center stacking scheme shown, under the condition that the orthographic projections of the chip carrier 2 and the coil support 11 are separated from each other, the chip packaging part no longer occupies the main stacking path of the magnetic circuit system and the vibration system, so that this application can still take into account the requirements of low profile of the module and acoustic structure assembly while maintaining the chip integration.

[0068] This section on implementation methods mainly combines... Figures 3 to 6 An explanation is provided. Among them, Figure 3 It can be used to understand the connection relationship between chip 8, bonding wire 9, chip carrier 2, external pin part 3 and coil connection part 4; Figure 4 It can be used to understand the concave state of the encapsulation substrate 10 and the soldering area after molding and encapsulation; Figure 5 It can be used to understand the overall composition and assembly levels of each component; Figure 6 It can be used to understand the stacking relationship of modules in the thickness direction; Figure 7 It can be used to help illustrate the structural differences between this application and the traditional center-stacked scheme.

[0069] In another embodiment, based on the foregoing embodiments, such as Figures 4 to 6As shown, the coil connection portion 4 includes a first window-type soldering area 411 and a second window-type soldering area 412 that are spaced apart from each other. Both the first window-type soldering area 411 and the second window-type soldering area 412 are exposed in the coil connection portion 4, that is, soldering areas recessed into the first surface. In this embodiment, the term "window-type soldering area" refers to the soldering area exposed on the first surface at the corresponding position of the coil connection portion 4 after the encapsulation substrate 10 is formed, which is not covered by the encapsulation substrate 10. By setting the soldering areas as two independent areas that are spaced apart from each other, they can respectively correspond to the two lead ends of the coil 12, so that the two lead ends of the coil 12 can be spot-welded to the first window-type soldering area 411 and the second window-type soldering area 412 respectively. Thus, on the one hand, it is beneficial to establish the electrical connection relationship between the two lead ends of the coil 12 and the drive output path of the chip 8 respectively, and on the other hand, it is also beneficial to control the soldering position and reduce the possibility of mutual interference between adjacent solder points. Furthermore, since the first window-type welding area 411 and the second window-type welding area 412 are directly recessed into the first surface, the spot welding operation of the lead end of the coil 12 can be directly completed on the outer surface of the package substrate 10 without the need to introduce an additional adapter structure, thus taking into account both connection reliability and assembly accessibility.

[0070] In this application, the terms "first" and "second" in "first window-type soldering area 411" and "second window-type soldering area 412" are only used to distinguish between two soldering areas that are spaced apart from each other, and do not indicate any limitation on their spatial position, arrangement order, or proximity to the chip 8. Figure 4 In the illustrated embodiment, the one closer to chip 8 can be designated as the first window-type soldering area 411, and the other as the second window-type soldering area 412. In other embodiments, the designations can be reversed, or the two window-type soldering areas can be arranged approximately symmetrically with respect to the mounting area of ​​the coil support 11. As long as both soldering areas serve as soldering connection areas for the two leads of the coil 12 and satisfy the electrical connection relationship with the coil connection portion 4, they fall within the protection scope of this application.

[0071] In an optional embodiment, the first window-type welding area 411 and the second window-type welding area 412 may be respectively provided at the two welding ends of the coil connection part 4 and located near the installation area of ​​the coil bracket 11, so as to shorten the connection path between the lead end of the coil 12 and the coil connection part 4.

[0072] It should be understood that the specific shape, area and relative position of the first window-type welding area 411 and the second window-type welding area 412 can be adjusted according to the size of the lead end of the coil 12, the spot welding process window and the surface space of the package substrate 10, and this application does not limit it.

[0073] For example, the first window-type welding area 411 and the second window-type welding area 412 are arranged at intervals along the extension direction of the coil support 11, and the distance between their centers can be 1.0 mm to 10.0 mm. For example, in one example, the distance between their centers can be 2.8 mm to accommodate both the space for the welding electrode to enter and the electrical insulation distance between the two solder joints. In one embodiment, the surface size of a single window-type welding area can be 0.30 mm × 0.3 mm to 1.5 mm × 2.0 mm.

[0074] For example, the first window-type welding area 411 and the second window-type welding area 412 can be 0.8mm × 1.2mm respectively; or 0.5mm × 0.8mm respectively.

[0075] It is understood that the above examples are only used to facilitate understanding of quantitative relationships and orders of magnitude, and do not constitute any additional limitation on this application.

[0076] In another example, the center-to-center distance between the two can be 3.5mm to accommodate wiring scenarios with larger lead-to-lead spacing for coil 12.

[0077] In another embodiment, the chip carrier 2 includes a carrier platform. The carrier platform and the remainder of the lead frame have a height difference in the thickness direction of the lead frame. Figure 1 , Figure 3 and Figure 4 It is understood that the carrier platform can be formed at the corresponding position of the chip carrier portion 2, so that after the chip 8 is mounted on the carrier platform, it is not in the same plane in the thickness direction as the external pin portion 3, the coil connection portion 4 and the other lead frame portions connected thereto. By setting a height difference, the mounting area of ​​the chip 8 can be distinguished from the surrounding lead area in three-dimensional space, thereby providing a more suitable structural basis for the mounting of the chip 8, the lead-out of the bonding wires 9 and subsequent molding and packaging.

[0078] After molding and encapsulation, a Mark point can be identified by laser forming on the first surface of the encapsulation substrate 10. The Mark point can be used as one of the registration references between the surface image after molding and the position data of the bonding wire 9 recorded before molding, in order to determine the orientation and coordinate mapping relationship of the monomer.

[0079] Furthermore, the height difference allows the packaging material to form a more stable covering relationship around the chip carrier 2, enhancing the bonding stability between the chip 8 and the lead frame. It should be understood that the height difference can be manifested as the carrier protruding upward relative to the rest of the lead frame, or it can be manifested as being recessed downward relative to the rest of the lead frame. As long as the carrier and the rest of the part form a non-coplanar structural relationship in the thickness direction, it can fall within the protection scope of this application.

[0080] For example, in one embodiment, the height difference between the carrier platform and the rest of the lead frame can be 0.02 mm to 0.2 mm. For instance, a height difference of 0.04 mm can create a thickness hierarchy between the chip mounting area and the surrounding lead area without causing difficulties in local molding filling. In another example, a height difference of 0.08 mm is beneficial for further reducing the protrusion of the chip 8 above the package substrate 10, thereby reserving more thickness space for the coil support 11, the magnetic circuit system, and the vibration system.

[0081] The height difference can be formed by partial half-etching; in one embodiment, the surrounding lead frame area other than the mounting carrier area of ​​chip 8 can be partially etched to thin it, so that the carrier stage retains a relatively large thickness, forming a stepped structure, and making it easier for subsequent molding materials to cover the surrounding thinned area.

[0082] It is understood that the above examples are only used to facilitate understanding of quantitative relationships and orders of magnitude, and do not constitute any additional limitation on this application.

[0083] In a further embodiment, the magnetic circuit system includes a ring magnet 13, and the vibration system includes a vibrating diaphragm 14, with the ring magnet 13 located between the coil support 11 and the vibrating diaphragm 14. Figure 5 and Figure 6 As shown, the coil support 11 serves as a mounting support for the coil 12 and the annular magnet 13. The annular magnet 13 and the coil 12 cooperate to form an electromagnetic drive structure. The diaphragm 14 is disposed on the outside of the annular magnet 13 and vibrates in response to the electromagnetic drive during operation, thereby achieving acoustic output. By placing the annular magnet 13 between the coil support 11 and the diaphragm 14, it is beneficial to form a relatively compact magnetic drive path within a limited thickness, and it is also beneficial to stack the magnetic circuit system and the vibration system in an orderly manner along the thickness direction on the packaging substrate 10. Combined with the aforementioned projection separation relationship between the chip carrier 2 and the coil support 11 on the plane, the mounting height of the magnetic circuit system and the vibration system occupied by the chip 8 packaging part can be further avoided.

[0084] In another embodiment, the package substrate 10 is formed of a molding material. The molding material covers the chip 8, the bonding wires 9 connected to the chip 8, and the portion of the lead frame located between the external pin portion 3 and the coil connection portion 4, with the end of the external pin portion 3 exposed on the side surface, and the first windowed soldering area 411 and the second windowed soldering area 412 of the coil connection portion 4 recessed within the first surface. Figure 3 and Figure 4It is understood that after the chip 8 is mounted and connected to the external lead portion 3 and the coil connection portion 4 via bonding wires 9, a packaging substrate 10 can be formed around the chip 8 through a molding process. The molding material can encapsulate and protect the chip 8 and the bonding wires 9, while leaving the ends of the external lead portion 3 and the soldering area in the coil connection portion 4 uncovered. Here, the side surface refers to the side surface formed on the outer periphery of the packaging substrate 10 after the array lead frame is divided into individual units along the dicing path; the ends of the external lead portion 3 are exposed on this side surface after the individual units are divided.

[0085] Therefore, the end of the external pin portion 3 can serve as the lead-out portion for external electrical connection of the module, while the first window-type soldering area 411 and the second window-type soldering area 412 located on the first surface can serve as the soldering connection portion for the lead end of the coil 12. In other words, while forming a chip packaging protection structure, the same packaging substrate 10 also reserves exposed areas with different orientations for external electrical connection and internal coil 12 connection, so that the packaging substrate 10 has multiple functions such as packaging, protection, support and assembly interface.

[0086] Furthermore, since the molding material covers the lead frame portion located between the external pin portion 3 and the coil connection portion 4, the chip 8 and the bonding wire 9 can be stably encapsulated inside the package substrate 10, while the soldering area in the coil connection portion 4 can remain recessed on the first surface to facilitate subsequent spot welding processes. Meanwhile, the ends of the external pin portion 3 are exposed on the side surface, allowing for easy electrical connection to external circuits even after the module is assembled.

[0087] Therefore, the encapsulation substrate 10 not only encapsulates the chip 8 and bonding wires 9, but also serves as the basic carrier for connecting the external pin part 3, the coil connection part 4 and the subsequent acoustic assembly structure, thereby improving the overall integration of the module and reducing the space occupied by the external connection structure.

[0088] This section on implementation methods mainly combines... Figure 1 , Figures 3 to 6 An explanation is provided. Among them, Figure 1 It can be used to understand the planar layout relationship of the chip carrier 2, the external pin part 3 and the coil connection part 4 in the unit area 1; Figure 3 It can be used to understand the connection relationship between chip 8, bonding wire 9 and various parts of the lead frame; Figure 4 It can be used to understand the exposure of the encapsulation substrate 10 after molding and the first windowed soldering area 411 and the second windowed soldering area 412, i.e., the recessed state. Figure 5 and Figure 6 It can be used to understand the overall assembly hierarchy and thickness direction relationship between the circular magnet 13, the vibrating diaphragm 14, the coil support 11 and the packaging substrate 10.

[0089] In another embodiment, such as Figure 1 and Figure 2 As shown, the lead frame structure includes a frame body and multiple unit regions 1 connected by the frame body. The multiple unit regions 1 are arranged in an array on the frame body to facilitate the parallel manufacturing of multiple single modules on the same lead frame strip. Figure 3 The area enclosed in yellow dashed lines represents a single unit region 1. In this embodiment, the "frame body" refers to the overall frame portion located around multiple unit regions 1 and used during manufacturing to maintain the relative positional relationship of each unit region 1 and the overall stability during handling. In this embodiment, "unit region 1" refers to the functional area corresponding to a single electromagnetic acoustic module unit within the array-type lead frame. The frame body may include process edges and their connecting structures for conveying, positioning, and maintaining the integrity of the array.

[0090] Specifically, each unit region 1 includes a chip carrier portion 2, an external pin portion 3, a coil connection portion 4, and a connection support portion 5 connecting the above portions. In this embodiment, the "connection support portion 5" refers to a lead frame connection structure that connects the chip carrier portion 2, the external pin portion 3, and the coil connection portion 4 into a single unit while maintaining their relative positional relationship. The connection support portion 5 serves two purposes: firstly, it maintains the overall structural stability of the unit region 1 during chip mounting, bonding, molding, and dicing processes; secondly, it provides basic support for the conductive paths and spatial layout between the chip carrier portion 2, the external pin portion 3, and the coil connection portion 4.

[0091] In this embodiment, in a plane perpendicular to the thickness direction of the lead frame, the chip carrier 2 is located at one edge of the corresponding unit region 1, and the coil connection 4 is spaced apart from the chip carrier 2. In other words, the chip carrier 2 is not located at the center of the unit region 1, but is offset at one edge of the unit region 1, while the coil connection 4 is located separately from the chip carrier 2. This planar partitioning method can reserve relatively independent edge space for the chip mounting area and the bonding area, and can also reserve an area in the middle of the unit region 1 suitable for the subsequent arrangement of the coil support 11, magnetic circuit system and vibration system, thereby reducing the space occupied by the chip 8 packaging part for the subsequent electromagnetic drive and acoustic structure installation.

[0092] Therefore, the lead frame structure is not only used to carry the chip 8 and the lead pins, but is specially designed to meet the subsequent assembly requirements of the electromagnetic acoustic module.

[0093] In one embodiment, the chip carrier 2 may be located at the left or right edge of the unit region 1, while the coil connection 4 is disposed on the other side or in the middle region, spaced apart from the chip carrier 2. It should be understood that the limitation that the chip carrier 2 is located at "one edge" is intended to partition it with the coil connection 4 and subsequent electromagnetic drive structure on a plane, and does not limit it to being located on the left or right side. As long as the chip carrier 2 is offset from the center of the unit region 1 and forms a spaced arrangement with the coil connection 4 to facilitate subsequent module assembly and low-profile structure formation, it falls within the scope of protection of this application.

[0094] In another embodiment, the chip carrier 2 includes a carrier platform formed by a semi-etching process, the carrier platform having a stepped structure. Figure 1 and Figure 3 It is understood that the "semi-etching process" referred to in this embodiment refers to a processing method in which a portion of the thickness of a local area of ​​the lead frame blank is removed so that the target area and the surrounding area form a height difference in the thickness direction; the "stepped structure" referred to in this embodiment refers to a stepped transition structure formed by the thickness change between the carrier platform and the surrounding area of ​​the chip carrier 2.

[0095] In one embodiment, the carrier platform may form an upwardly protruding step relative to the surrounding lead frame area; in another embodiment, the carrier platform may also form a downwardly recessed step relative to the surrounding area. By using a semi-etching process to form the carrier platform, the three-dimensional spatial distinction between the chip mounting area and the surrounding conductive area can be improved, and the subsequent molding material can form a stable coating around the carrier platform, thereby improving the bonding reliability between the chip 8 and the lead frame.

[0096] For example, in one embodiment, the height difference between the support platform and the surrounding lead frame area can be 0.02 mm to 0.2 mm. For instance, a stepped structure with a height difference of 0.04 mm can be formed to balance chip 8 mounting flatness and molding fill continuity; in another example, a stepped structure with a height difference of 0.08 mm can be formed to reduce the protrusion of chip 8 above the subsequent package substrate 10 and to reserve more thickness space for the subsequent coil support 11, magnetic circuit system, and vibration system. It is understood that the above values ​​are only used to illustrate the feasible range and order of magnitude of the height difference and do not constitute an additional limitation on the scope of protection of this application.

[0097] In a further embodiment, the connecting support 5 is provided with cutting alignment marks and / or thinning grooves 7, and a cutting channel 6 is provided between two adjacent unit regions 1. In this embodiment, the "cutting alignment mark" refers to an identification structure used to provide an identification reference in subsequent cutting, punching, or separation processes; the "thinning groove 7" refers to a groove-shaped structure formed on the connecting support 5 to reduce local thickness or guide subsequent separation paths; and the "cutting channel 6" refers to an area provided between adjacent unit regions 1 to define the cutting and separation position. By providing cutting alignment marks on the connecting support 5, a positional reference can be provided for subsequent segmentation processes after the array-type lead frame has been molded; by providing thinning grooves 7, a local cross-sectional reduction structure can be formed in the corresponding area, thereby facilitating the stable formation of subsequent cutting paths and reducing the impact on the functional parts of adjacent unit regions 1 during separation; by providing cutting channels 6 between two adjacent unit regions 1, the boundary positions of each individual module can be further clarified, enabling the array-type lead frame to be divided into multiple independent units along a predetermined path after molding and packaging.

[0098] For example, in one embodiment, the depth of the thinning groove 7 can be 0.1 mm to 3.0 mm. For instance, the depth of the thinning groove 7 can be 1.0 mm to form an identifiable separation guide structure while ensuring the overall mechanical stability of the connecting support 5; in another example, the depth of the thinning groove 7 can be 1.5 mm to enhance the guiding effect on the subsequent cutting path. The width of the cutting track 6 can be set according to the lead frame material thickness, the individual component boundary requirements after molding, and the segmentation process window, for example, it can be 0.10 mm to 0.50 mm. It is understood that the specific shape, size, and number of the thinning groove 7 and the cutting track 6 can be adjusted according to the array arrangement density, segmentation method, and processing accuracy requirements, and this application does not limit this.

[0099] Furthermore, the array-type lead frame structure, by arranging multiple unit regions 1 on the same frame body, can form a continuous connection with the molding process, the cutting process, and subsequent assembly processes. In other words, the lead frame structure in this application does not only focus on the planar shape of a single chip carrier, but also considers the edge layout of the chip carrier 2, the welding connection requirements of the coil connection 4, the structural stability of the connection support 5, and the requirements of array-type manufacturing and subsequent cutting and separation.

[0100] Therefore, this lead frame structure can serve as the common basic structure for the electromagnetic acoustic module and subsequent manufacturing methods, providing support for the overall technical solution of chip 8 being offset from the central stacking path, the soldering area being recessed into the first surface, and the single-unit cutting and release.

[0101] In one embodiment, when integrating the driver chip within the electromagnetic acoustic module, conventional methods often result in the chip package, magnetic circuit system, and vibration system being stacked in series along the module's thickness, thus compressing the effective assembly space in the middle and limiting the module's low profile. Therefore, this embodiment integrates the chip packaging process, coil connection process, and acoustic structure assembly process onto the same packaging substrate 10, and positions the chip carrier 2 at one edge of the unit region 1. This spatially separates the chip packaging portion from the subsequent electromagnetic drive and acoustic assembly portions, providing a continuous and feasible process path for the formation of the low-profile module.

[0102] Specifically, this manufacturing method first provides an arrayed lead frame. Combined with... Figure 2 As shown, the array-type lead frame may include multiple unit regions 1, which are arranged in an array on the same frame body to facilitate the unified completion of pre-processing steps such as chip 8 mounting, bonding, molding, and dicing. Each unit region 1 has a chip carrier portion 2, an external pin portion 3, and a coil connection portion 4 located on one side edge of the unit region 1. Adjacent unit regions 1 can be separated by a dicing channel 6. The purpose of using an array-type lead frame is to enable multiple module units to be formed to be processed synchronously on the same carrier, thereby improving the consistency of the pre-packaging process and reducing the cumulative errors caused by individual unit mounting and positioning. Since the chip carrier portion 2 is located on one side edge of the unit region 1, rather than at the center, the planar partitioning relationship between the chip packaging area and the subsequent acoustic assembly area is predetermined at the array-type lead frame stage.

[0103] Subsequently, chip 8 is fixed to chip carrier 2, and chip 8 is connected to external pin portion 3 and coil connection portion 4 respectively via bonding wires 9. Figure 3 As shown, in one embodiment, conductive adhesive can be first applied to the surface of the support platform corresponding to the chip carrier 2, and then the chip 8 can be mounted on the support platform and the conductive adhesive can be cured to form a stable mechanical bond between the chip 8 and the chip carrier 2. After the chip 8 is fixed, the input / output terminals of the chip 8 can be connected to the external pin portion 3 and the coil connection portion 4 respectively using a bonding process. The bonding wire 9 between the chip 8 and the external pin portion 3 is used to form the electrical signal output path of the module to the outside, and the bonding wire 9 between the chip 8 and the coil connection portion 4 is used to form the internal driving path between the chip 8 and the coil 12. By preferentially arranging the chip 8 and the bonding wire 9 on one side of the unit area 1, the central area used for subsequently mounting the coil support 11, the magnetic circuit system, and the vibration system can be kept relatively intact, thereby providing a prerequisite for low profile.

[0104] After the chip 8 is mounted and bonded, the portion of the chip 8, bonding wires 9, and lead frame located between the external pin portion 3 and the coil connection portion 4 is molded and encapsulated to form a package substrate 10 having a first surface, a second surface, and a side surface. The windowed soldering area of ​​the coil connection portion 4 is recessed into the first surface, while the end of the external pin portion 3 is exposed on the side surface. Figure 4 As shown, in one embodiment, a molding process can be used to encapsulate the chip 8, bonding wires 9, and part of the lead frame with molding material, thereby forming a package substrate 10.

[0105] In this embodiment, the first surface refers to the side surface that is subsequently used to fix the coil support 11 and exposes the welding area; the second surface is the side surface that is opposite to the first surface; the side surface is the outer peripheral surface that connects the first surface and the second surface. During molding, the first window-type welding area 411 and the second window-type welding area 412 in the coil connection part 4 are not covered by the molding material through the mold cavity structure and local avoidance design, so that they remain recessed in the first surface after molding; at the same time, the end of the external pin part 3 remains exposed on the side surface so that the subsequent module can be connected to the external circuit. Through this molding step, the preceding electronic packaging part and the subsequent mechanical / acoustic assembly base are uniformly established on the same packaging base 10, so that the packaging base 10 not only undertakes the function of encapsulating and protecting the chip 8 and the bonding wire 9, but also undertakes the assembly and bearing function of the subsequent coil support 11, magnetic circuit system, vibration system and top cover 15.

[0106] After molding, the array-type lead frame is divided along the cutting groove 6 to form multiple units. In this embodiment, a "unit" refers to an independent packaging unit corresponding to a single electromagnetic acoustic module, formed by dividing the array-type lead frame. It internally encapsulates the chip 8, bonding wires 9, and part of the lead frame, and exposes the soldering area and external pins required for subsequent assembly on its surface. In one embodiment, punching, cutting, or other methods suitable for separating the array-type lead frame can be used to separate the multiple unit regions 1 along the cutting groove 6. Since the cutting groove 6 is pre-set between adjacent unit regions 1, the unit release can be completed without significantly affecting the integrity of the chip 8 packaging area and soldering area. Therefore, the preceding array packaging process and the subsequent unit-level assembly process can be smoothly connected.

[0107] After the monomer is formed, the coil support 11 with coil 12 is fixed to the first surface of the monomer, and the lead end of coil 12 is electrically connected to coil connection part 4. Figure 5 and Figure 6As shown, in one embodiment, a coil support 11 assembly with the coil 12 already wound can be provided in advance, and then the coil support 11 can be fixed to the middle region of the first surface of the package substrate 10 by adhesive. Since the chip 8 and its package portion are located on one side edge of the package substrate 10, the coil support 11 can be disposed in the middle region not occupied by the chip 8, thereby avoiding the coil support 11 and the chip package from being directly stacked vertically in the thickness direction. After the coil support 11 is fixed, the two leads of the coil 12 can be led to the first window-type soldering area 411 and the second window-type soldering area 412 in the coil connection portion 4, respectively, and a solder connection can be formed. By making the soldering area directly recessed into the first surface, the leads of the coil 12 can be directly connected on the outer surface of the package substrate 10 without the need for an intermediate adapter plate or external conductive connector, which helps to shorten the internal connection path and reduce the additional thickness occupied.

[0108] After the coil support 11 and coil 12 are assembled, the magnetic circuit system and vibration system are assembled on the side of the coil support 11 opposite to the packaging substrate 10. Figure 5 and Figure 6 Taking the illustrated embodiment as an example, the magnetic circuit system may include a circular magnet 13, and the vibration system may include a vibrating diaphragm 14. During assembly, the circular magnet 13 can be first installed on the corresponding mounting position of the coil support 11, and then the vibrating diaphragm 14 can be installed at a predetermined position outside the circular magnet 13, so that the circular magnet 13 is located between the coil support 11 and the vibrating diaphragm 14. Through this assembly relationship, the coil 12, the circular magnet 13, and the vibrating diaphragm 14 can form a compact electromagnetic drive and vibration sound generation structure in the central region of the package substrate 10. Since the chip 8 package is offset to one side edge on the plane, the main stacking path of the magnetic circuit system and the vibration system in the thickness direction will not be occupied by the chip package, which is beneficial to retain more magnetic circuit space and acoustic cavity 16 space within the limited module height.

[0109] Finally, the top cover 15 is fixed to one side of the first surface of the packaging substrate 10 to form an electromagnetic acoustic module. In one embodiment, the top cover 15 can be fastened, glued, or otherwise fixed to the corresponding joint of the packaging substrate 10, so that the top cover 15 and the packaging substrate 10 together form an acoustic cavity 16. Thus, the chip 8 package, internal electrical connections, coil drive structure, magnetic circuit system, vibration system, and acoustic cavity 16 are integrated within the same module.

[0110] Compared to a scheme that places the chip package in the central region and forces the magnetic circuit system and vibration system to be stacked in series on top of it, the manufacturing process of this embodiment achieves coordinated organization of the preceding electronic packaging and the subsequent acoustic assembly, thereby helping to reduce the overall thickness of the module while balancing chip integration and acoustic assembly requirements. Therefore, the manufacturing method of this embodiment not only enables the continuous manufacturing of electromagnetic acoustic modules but also directly supports the goal of low-profile module design at the process level.

[0111] In one embodiment, fixing the chip 8 to the chip carrier 2 includes attaching the chip 8 to the chip carrier 2 using conductive adhesive. Figure 3 As shown, after the pre-array lead frame is prepared, the surface of the carrier platform corresponding to the chip carrier 2 can be cleaned to remove oxides, particles, or residual oil. Then, a conductive adhesive layer is applied to the surface of the carrier platform. In this embodiment, "conductive adhesive" refers to an adhesive material that combines mechanical bonding and conductive properties. It can be silver paste, silver epoxy conductive adhesive, or other conductive adhesive materials suitable for chip 8 mounting. The conductive adhesive can be formed on the surface of the carrier platform by dispensing. The dispensing pattern can be located in the central area of ​​the carrier platform, or it can be formed into a strip, rectangular, or multi-point distributed adhesive layer according to the distribution of the bottom electrodes of the chip 8, to balance the flatness of the chip 8 mounting and the bonding strength after curing.

[0112] In one embodiment, chip 8 can be picked up from a tray or wafer-cut chip carrier using a chip mounting device and placed on a conductive adhesive layer according to a predetermined mounting direction, so that the edge contour of chip 8 maintains a predetermined alignment relationship with the corresponding edge of chip carrier 2. Since chip carrier 2 is located on one side edge of unit region 1, it is preferable to align the pins or pads of chip 8 towards the direction of external pin portion 3 and coil connection portion 4 during mounting, so that the lead-out path of subsequent bonding wires 9 is shorter and clearer. After chip 8 is placed, it can be pressed lightly to make full contact with conductive adhesive, and then heated and cured to form a stable adhesive layer, thereby fixing chip 8 to chip carrier 2. The curing method can be hot plate curing, oven curing, or pulse heating curing, and this application is not limited to this. It is understood that those skilled in the art can also use insulating adhesive.

[0113] The above mounting method enables the chip 8 to be stably positioned on the chip carrier 2 in the thickness direction, providing a reliable foundation for the subsequent connection of bonding wires 9 and molding packaging.

[0114] For example, in one embodiment, the thickness of the conductive adhesive layer can be 0.005 mm to 0.03 mm. For instance, the thickness of the conductive adhesive layer can be 0.01 mm to reduce the additional lifting of the chip 8 in the thickness direction while ensuring adhesive strength. In another example, the thickness of the conductive adhesive layer can be 0.02 mm to accommodate situations where there are slight flatness deviations at the bottom of the chip 8 or minor roughness on the surface of the support platform. It is understood that the above values ​​are only used to illustrate the feasible range and order of magnitude of conductive adhesive mounting and do not constitute additional limitations on this application.

[0115] Furthermore, after the chip 8 is mounted and cured, a bonding process can be used to connect the chip 8 to the external lead portion 3 and the coil connection portion 4, respectively. Since the chip 8 is fixed to the chip carrier portion 2 located on one side edge using conductive adhesive, the bonding wires 9 can be mainly distributed on one side of the unit area 1, without occupying the central area used for setting the coil support 11 and the magnetic circuit system. Thus, by mounting the chip 8 with conductive adhesive and using an edge-mounted carrier layout, not only can the mechanical fixation of the chip 8 be achieved, but it also provides a basis for the spatial organization of the subsequent low-profile module.

[0116] In one embodiment, the lead end of the coil 12 is electrically connected to the coil connection portion 4, including welding the lead end of the coil 12 to the open-type welding area of ​​the coil connection portion 4 by spot welding. Figures 4 to 6 As shown, after molding and packaging and completing the individual component separation, the first surface of the packaging substrate 10 retains recessed welding areas, such as the first window-type welding area 411 and the second window-type welding area 412. After the coil support 11 is fixed to the first surface of the packaging substrate 10, the two leads of the coil 12 can be led out towards the first window-type welding area 411 and the second window-type welding area 412, respectively. The "spot welding process" referred to in this embodiment refers to the connection process in which the leads of the coil 12 form a welded joint with the window-type welding area through local heat input and / or local pressure. This process can be completed by a spot welding head, a welding power source, a clamping mechanism, and a positioning mechanism.

[0117] In one embodiment, the coil support 11 and the unit can be fixed first using a positioning clamp, and then the two leads of the coil 12 can be pulled above the corresponding welding areas. Subsequently, welding electrodes can be pressed against the contact positions between the leads and the open-window welding areas, and preset welding energy and welding pressure can be applied to form a partial welding connection between the leads and the welding areas. After spot welding is completed, the two leads of the coil 12 are electrically connected to the coil connection part 4, and then a complete driving circuit is formed with the chip 8 through the coil connection part 4, the bonding wire 9, and the coil connection part 4. Since the welding area is recessed within the first surface of the packaging substrate 10, the welding process can be completed directly on the outer surface of the packaging substrate 10 without the need for an intermediate transition plate, flexible plate, or secondary lead-out structure, which helps to shorten the internal connection path and reduce the vertical space occupied by the connection structure.

[0118] For example, in one embodiment, the single-point welding time can be 0.5ms to 8ms. For instance, 1.5ms can be used to achieve faster welding in scenarios with fine wire diameter leads; in another example, 3ms can be used to adapt to situations where the welding area is relatively large or the contact area of ​​the lead end is relatively large. The welding energy and welding pressure can be matched according to the material of the coil 12 lead end, wire diameter, welding area size, and welding equipment capability, and this application does not limit them. It is understood that the above values ​​are only used to illustrate the feasible order of magnitude of the spot welding process and do not constitute an additional limitation on this application. Directly welding the coil 12 lead end to the concave window-type welding area by spot welding not only helps to improve the reliability of electrical connection, but also helps to maintain the low profile feature of the module in subsequent assembly.

[0119] Optional, see Figure 8 A flowchart of a manufacturing method provided in an embodiment of this application includes steps S101 to S104, wherein:

[0120] S101: Acquire a surface image of the first surface of the monomer;

[0121] S102: Determine the boundary contour of the windowed welding area of ​​the coil connection part 4 based on the surface image;

[0122] S103: Obtain the position data of the bonding wire 9 recorded before the molding and encapsulation, and determine the projection boundary of the area where the bonding wire 9 is located in the plane perpendicular to the thickness direction of the encapsulation substrate 10 based on the position data;

[0123] S104: Generate multiple candidate spot welding positions within the window-type welding zone.

[0124] In one embodiment, before welding the lead end of the coil 12 to the windowed welding area of ​​the coil connection portion 4 via spot welding, the method further includes: acquiring a surface image of the first surface of the monomer; determining the boundary contour of the windowed welding area of ​​the coil connection portion 4 based on the surface image; acquiring the position data of the bonding wire 9 recorded before molding and packaging, and determining the projected boundary of the area where the bonding wire 9 is located in a plane perpendicular to the thickness direction of the packaging substrate 10 based on the position data; and generating multiple candidate spot welding positions within the windowed welding area. The purpose of this step is to avoid roughly determining the spot welding position based solely on the geometric center of the welding area, but rather to incorporate the spatial distribution of the bonding wire 9 formed by the previous bonding process into the subsequent spot welding position decision, thereby improving the reliability of the welding position selection.

[0125] Specifically, in this embodiment, "monocell" refers to an independent packaging unit corresponding to a single electromagnetic acoustic module, formed by molding and dividing an array-type lead frame along the cutting path 6; "first surface of the monocell" refers to one side surface of the packaging substrate 10 after molding and encapsulation, which is used for the recessed window-type soldering area and for mounting the coil support 11; "surface image" refers to an image acquired by an image acquisition device from the direction of the first surface that reflects the recessed state and boundary information of the soldering area. This image can be a two-dimensional grayscale image or a color image, as long as it can distinguish the soldering area from the surrounding surface of the packaging substrate 10.

[0126] In one embodiment, the image acquisition device may include an industrial camera, a lens, and an illumination assembly. The industrial camera may be positioned above or diagonally above the spot welding station to acquire image information of the current first surface of the monomer before the spot welding process is performed. The illumination assembly may employ a ring light source, a coaxial light source, or a side light source to enhance the reflection difference between the welding area and the surface of the package substrate 10. This application does not rely on a specific type of camera or light source; its inventive point lies not in the image acquisition device itself, but in combining the acquired surface image with previously recorded bonding wire 9 position data for generating candidate solder joint positions.

[0127] In one embodiment, the timing for acquiring the surface image can be set as follows: after the individual component cutting is completed, the coil support 11 is fixed, and the lead end of the coil 12 has been brought to the vicinity of the welding area, but before the formal spot welding. This timing is chosen because the actual state of the first surface at this point is close to the final welding state, accurately reflecting the exposure of the window-type welding area, i.e., the concave boundary, and facilitating subsequent spot welding decisions based on the current position of the lead end of the coil 12. If the image is acquired immediately after molding, the boundary contour of the welding area can also be obtained, but it cannot reflect the actual assembly state after the lead end of the coil 12 is brought out; if the image is acquired after spot welding, it loses its significance for weld point determination. Therefore, the above-mentioned acquisition timing helps improve the accuracy of weld point determination without increasing additional rework.

[0128] After acquiring the surface image, the boundary contour of the windowed welding area of ​​the coil connection 4 can be determined based on the surface image. In this embodiment, the "boundary contour" refers to the contour line information characterizing the position of the outer periphery of the welding area. In one embodiment, the surface image can first undergo contrast enhancement or grayscale normalization processing to enhance the image difference between the concave welding area and the surface of the packaging substrate 10; subsequently, readily available image processing algorithms can be used to extract the boundary of the welding area. For example, threshold segmentation and connected component extraction methods can be used to first separate the concave welding area from the image whose brightness or reflectance characteristics differ from the surface of the packaging substrate 10, and then extract its outer periphery boundary using edge detection or contour tracking methods. Optionally, edge detection can use the Sobel operator, Canny operator, or other readily available algorithms suitable for industrial vision boundary extraction; contour tracking can use readily available methods based on connected component boundary search. This application is not limited to any particular image algorithm. The focus of this application is: to obtain the boundary contour of the welding area using the surface image, and to make this boundary contour participate in the subsequent generation of candidate spot welding positions.

[0129] While determining the boundary contour of the windowed welding area, the position data of the bonding wire 9 recorded before molding encapsulation is also acquired, and the projected boundary of the area where the bonding wire 9 is located in the plane perpendicular to the thickness direction of the encapsulation substrate 10 is determined based on the position data. "Position data" refers to information that characterizes the actual spatial or planar position of the bonding wire 9. This information can be acquired and stored by a vision inspection device, the recording system built into the bonding equipment, or other position detection units after the chip 8 has been bonded and before molding encapsulation. Since the bonding wire 9 is encapsulated by the encapsulation substrate 10 after molding, its true position cannot be directly observed from the image of the first surface. Therefore, this embodiment uses data recorded before molding to restore its planar distribution in the current single unit. Subsequently, the position data can be mapped to the coordinate system of the current first surface to obtain the projected boundary of the area where the bonding wire 9 is located in the plane perpendicular to the thickness direction of the encapsulation substrate 10. In this way, the spatial information of the preceding bonding process can participate in the position decision of the subsequent spot welding process, thereby forming a cross-process spatial coupling.

[0130] In one embodiment, after obtaining the boundary contour of the windowed welding zone and the projected boundary of the area where the bonding wire 9 is located, multiple candidate spot welding positions can be generated within the windowed welding zone. In this embodiment, "candidate spot welding positions" refers to a pre-selected set of positions located within the welding zone for subsequent screening of target spot welding positions. The candidate spot welding positions can be generated in the following ways: establishing a regular grid within the welding zone at a preset step size and using each grid node as a candidate point; or distributing points along the effective area within the welding zone using polar coordinates; or randomly or semi-randomly generating several candidate points in areas that meet boundary avoidance conditions. Preferably, the step size can be selected based on the welding zone size and the contact area of ​​the spot welding electrode, ensuring that the number of candidate points covers the effective welding zone without causing excessive computational load for subsequent screening. Therefore, the determination of the weld point position is no longer a single fixed point, but rather a selection from a candidate set generated by combining the welding zone and bonding wire 9 distribution information, providing a basis for further screening of target spot welding positions.

[0131] In this way, compared with the method of determining the solder joint based solely on the geometric center of the welding area, this method can simultaneously consider the distribution of internal wires formed by the previous bonding process and the geometric boundary of the current welding area, thereby reducing the potential process risks caused by the spot welding position being too close to the internal bonding wire 9 area or too close to the edge of the welding area, and improving the consistency and reliability of the welding connection between the lead end of coil 12 and the windowed welding area.

[0132] In one embodiment, after generating multiple candidate spot welding positions, the candidate spot welding positions can be further screened to determine a target spot welding position that is more suitable for subsequent spot welding connections. Specifically, for each candidate spot welding position, a first distance from the candidate spot welding position to the projected boundary and a second distance to the boundary contour can be calculated, and a target spot welding position can be selected from candidate spot welding positions whose first distance is greater than a first preset threshold and whose second distance is greater than a second preset threshold.

[0133] In one embodiment, the candidate spot welding position, projection boundary, and boundary contour are all represented in the same planar coordinate system. This planar coordinate system can be obtained by calibrating and transforming the image coordinate system of the first surface of the unit and the equipment station coordinate system. Specifically, the end position of the external pin portion 3 exposed on the side surface, and the boundary contour positions of the first windowed welding area 411 and the second windowed welding area 412 can be used as the surface registration reference of the unit after molding; and using the bonding endpoint coordinates in the bonding wire 9 position data recorded before molding and packaging, the bonding wire 9 is projected onto the corresponding plane of the first surface in the direction perpendicular to the thickness of the packaging substrate 10, thereby obtaining the projection boundary of the area where the bonding wire 9 is located. Preferably, a closed area boundary can be formed on both sides of the theoretical projection line of the bonding wire 9 by extending it with a preset envelope width to serve as the projection boundary. The envelope width can be determined according to the wire diameter, arc height deviation, and molding position deviation of the bonding wire 9, for example, it can be 0.01mm to 0.05mm.

[0134] In one embodiment, candidate spot welding positions can be generated using a regular grid within the first windowed welding area 411 or the second windowed welding area 412. Specifically, sampling points can be distributed along both the length and width directions of the welding area with a preset sampling step size, ensuring that each candidate spot welding position is located within the welding area. The sampling step size can be determined based on the diameter of the spot weld head contact patch and the size of the welding area. For example, the sampling step size can be 0.01 mm to 0.05 mm. For instance, when the welding area size is approximately 0.50 mm × 0.80 mm, a sampling step size of 0.02 mm can be used; when the welding area size is approximately 0.80 mm × 1.20 mm, a sampling step size of 0.03 mm can be used. Through the above settings, the candidate point distribution can cover the main weldable area within the welding area without significantly increasing the computational load.

[0135] For any candidate spot weld location, the shortest distance to the projected boundary can be calculated by distributing the distances between the candidate spot weld location and each boundary point on the projected boundary, and this shortest distance is determined as the first distance. Simultaneously, the shortest distance to the boundary contour can be calculated by distributing the distances between the candidate spot weld location and each contour point on the boundary contour, and this shortest distance is determined as the second distance. Preferably, both the first and second distances are calculated using Euclidean distance to ensure that the distance values ​​better reflect the actual geometric proximity between the spot weld location and the relevant boundary.

[0136] In one embodiment, a first preset threshold is used to ensure a sufficient process safety distance is maintained between the candidate spot welding position and the projected boundary of the area where the bonding wire 9 is located, and a second preset threshold is used to ensure a sufficient edge allowance is maintained between the candidate spot welding position and the boundary contour of the welding area. The first preset threshold may be related to the following factors: the wire diameter of the bonding wire 9, the projected envelope width of the bonding wire 9, the heat-affected zone width of the spot weld, and the local heat conduction path of the lead frame; the second preset threshold may be related to the following factors: the effective contact radius of the spot weld head, the minimum side length of the welding area, and the range of plastic deformation expansion of the weld. For example, in one embodiment, the first preset threshold may be 0.03 mm to 0.20 mm, and the second preset threshold may be 0.02 mm to 0.15 mm. For example, in the case of fine wire diameter leads and small welding area, the first preset threshold may be 0.05 mm, and the second preset threshold may be 0.04 mm; in the case of large weld head size and dense distribution of bonding wires 9, the first preset threshold may be 0.10 mm, and the second preset threshold may be 0.06 mm. The above values ​​match the candidate spot welding location, welding area size, and the safe zone of the bonded wire 9 projection, which can balance the preservation of the solderable area and the safe avoidance of the internal wires.

[0137] In one embodiment, when there are more than one candidate spot welding position that meets the condition that "the first distance is greater than the first preset threshold and the second distance is greater than the second preset threshold", the target spot welding position can be further selected according to additional rules. For example, the candidate point with the largest sum of the first distance and the second distance can be selected from the candidate spot welding positions that meet the conditions; or, provided that the first distance meets the requirements, the candidate point with the largest second distance can be selected first, so that the weld point is relatively closer to the center of the welding area; or, the candidate spot welding position that is more conducive to the natural spread of the lead wire can be selected by combining the actual lead-out direction of the coil 12 lead end. Through the above screening process, the target spot welding position can simultaneously meet the internal wire avoidance requirements and the welding edge allowance requirements, thereby improving the consistency and reliability of the spot welding connection between the coil 12 lead end and the window-type welding area.

[0138] In one embodiment, the step of generating multiple candidate spot weld positions within the windowed welding zone may further include excluding boundary anomaly regions based on boundary curvature. Specifically, the local curvature of each boundary point on the boundary contour can be obtained, and boundary points with local curvature greater than a curvature threshold and their areas within a preset range can be marked as boundary anomaly regions. Candidate spot weld positions are then generated in the areas outside the boundary anomaly regions of the windowed welding zone.

[0139] In one embodiment, the boundary profile can be discretized and represented as a plurality of sequentially connected profile points. The sampling interval can be matched with the generation step size of the candidate spot welding position, for example, it can be 0.005 mm to 0.03 mm. For any boundary point, at least two adjacent boundary points can be selected to form a local neighborhood, and the local curvature of the boundary point can be determined based on the local neighborhood. For example, in one embodiment, the reciprocal of the radius of the circumcircle of the three points can be used as the local curvature; in another embodiment, the rate of change of the tangential angle between adjacent line segments can be used to approximate the local curvature. The term "local curvature" as used herein refers to a geometric quantity that reflects the degree of curvature of the boundary profile in a local region. When this value is large, it indicates that there are sharp corners, narrow bends, or irregular edges near the boundary position.

[0140] In one embodiment, the curvature threshold can be set based on the overall size of the welding area, the size of the spot weld contact patch, and the allowable proximity of the weld spot to the boundary. For example, the curvature threshold can be 3 mm. -1 ~20mm -1 For example, when the boundary of the welding area is relatively flat and it is desirable to exclude sharp corner areas more leniently, the curvature threshold can be set to 6mm. -1 When the overall outline of the welding area is relatively regular and only obviously sharp edges are excluded, the curvature threshold can be taken as 12mm. -1 The example values ​​above are not isolated values, but rather represent different scenarios with varying boundary regularity and welding allowance requirements.

[0141] After identifying the boundary point where the local curvature exceeds the curvature threshold, this boundary point and the area within a preset range can be further marked as a boundary anomaly region. The term "preset range" as used herein refers to a local area extending inward from the boundary point into the welding zone; it can be a fixed-radius area, a rectangular area, or an area projected along the boundary normal direction. In one embodiment, the preset range can be determined based on the contact spot radius of the spot weld and the plastic expansion width of the weld. For example, the preset range can be 0.02 mm to 0.10 mm. For instance, it can be 0.03 mm to exclude narrow neighborhoods near sharp corners; or it can be 0.06 mm to form a more adequate boundary anomaly exclusion zone when the weld head size is large or the weld expansion range is wide. Through the introduction of this preset range, the boundary anomaly region is no longer just a single boundary point, but forms an edge exclusion zone with practical process significance.

[0142] In one implementation, the preset ranges corresponding to all boundary points with local curvature greater than a curvature threshold can be merged to form a complete boundary anomaly region. Then, candidate spot weld positions are generated in the remaining region outside the boundary anomaly region. In other words, the generation of candidate spot weld positions is not simply a matter of placing points within the entire window-type welding area, but rather, abnormal regions with excessively large local boundary curvature are first eliminated, and then candidate points are generated in the remaining effective region.

[0143] This avoids candidate spot weld locations being too close to sharp corners, narrow edges, or local irregular boundaries, thus providing a more stable candidate set for subsequent dual-distance screening.

[0144] Furthermore, in one embodiment, the aforementioned local curvature calculation and boundary anomaly region elimination operations can be performed in the first windowed welding area 411 and the second windowed welding area 412, respectively. Since the dimensions, boundary shapes, and correspondences with the leads of the coil 12 may differ between the two welding areas, separate calculation and elimination help improve the effectiveness of candidate spot welding positions within each welding area. Thus, the final generation process of candidate spot welding positions can be divided into two layers: the first layer eliminates boundary anomaly regions based on local curvature and a preset range; the second layer generates candidate spot welding positions in the remaining areas according to a preset step size, which are then used for subsequent selection of target spot welding positions based on a first distance and a second distance. Through this process, the candidate spot welding positions are constrained not only by the overall boundary of the welding area but also by the local boundary morphology of the welding area, thereby improving the repeatability and process stability of the entire weld point decision-making process.

[0145] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the embodiments of this application, and the embodiments of this application are not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the embodiments of this application, and these modifications and improvements are also considered to be within the protection scope of the embodiments of this application.

Claims

1. An electromagnetic acoustic module, characterized in that, include: The encapsulation substrate has a first surface and a second surface disposed opposite to each other, and a side surface connecting the first surface and the second surface; A lead frame is embedded in the package substrate, and the lead frame includes a chip carrier, an external pin portion, and a coil connection portion; A chip is disposed on the chip carrier and encapsulated by the packaging substrate. The chip is electrically connected to the external pin portion and the coil connection portion respectively through bonding wires. A coil support is disposed on the first surface; A coil is mounted on the coil support, and the lead end of the coil is electrically connected to the coil connection part; A magnetic circuit system and a vibration system are disposed on the side of the coil support away from the packaging substrate, with the magnetic circuit system located between the coil support and the vibration system; The top cover is disposed on one side of the first surface of the encapsulation substrate and forms an acoustic cavity with the encapsulation substrate; In a plane perpendicular to the thickness direction of the packaging substrate, the orthographic projection of the chip carrier and the orthographic projection of the coil support are separate from each other.

2. The electromagnetic acoustic module according to claim 1, characterized in that, The coil connection portion includes a first open-window welding area and a second open-window welding area that are spaced apart from each other. The first open-window welding area and the second open-window welding area are welding areas recessed into the first surface of the coil connection portion. The two lead ends of the coil are spot welded to the first open-window welding area and the second open-window welding area, respectively.

3. The electromagnetic acoustic module according to claim 1, characterized in that, The chip carrier includes a carrier platform, and the carrier platform and the rest of the lead frame have a height difference in the thickness direction of the lead frame.

4. The electromagnetic acoustic module according to claim 1, characterized in that, The magnetic circuit system includes a circular magnet, and the vibration system includes a vibrating diaphragm, with the circular magnet located between the coil support and the vibrating diaphragm.

5. The electromagnetic acoustic module according to claim 2, characterized in that, The packaging substrate is formed of a molding material that covers the chip, the bonding wires connected to the chip, and the portion of the lead frame located between the external pin portion and the coil connection portion, and exposes the end of the external pin portion on the side surface of the packaging substrate, such that the first windowed soldering area and the second windowed soldering area are recessed into the first surface.

6. A lead frame structure, applied to an electromagnetic acoustic module as described in any one of claims 1 to 5, characterized in that, include: The frame body and multiple unit regions connected by the frame body are arranged in an array on the frame body. Each unit region includes a chip carrier, an external pin, a coil connection, and a connection support. In this configuration, within a plane perpendicular to the thickness direction of the lead frame, the chip carrier is located at one edge of the corresponding unit region, and the coil connection is spaced apart from the chip carrier.

7. The lead frame structure according to claim 6, characterized in that, The chip carrier includes a carrier platform formed by a semi-etching process, and the carrier platform has a stepped structure.

8. The lead frame structure according to claim 6, characterized in that, The connecting support is provided with cutting alignment marks and / or thinning grooves, and a cutting channel is provided between two adjacent unit areas.

9. A method for manufacturing an electromagnetic acoustic module, characterized in that, include: An array-type lead frame is provided, the array-type lead frame includes multiple unit regions, and a cutting channel is provided between two adjacent unit regions. Each unit region has a chip carrier, an external pin, and a coil connection. The chip carrier is located on one side edge of the corresponding unit region, and the coil connection is spaced apart from the chip carrier. The chip is fixed to the chip carrier, and the chip is connected to the external pin portion and the coil connection portion respectively by bonding wires; The chip, the bonding wire, and the lead frame located between the external pin portion and the coil connection portion are molded and packaged to form a package substrate having a first surface, a second surface, and a side surface. The coil connection portion is formed into a window-type soldering area recessed in the first surface, so that the end of the external pin portion is exposed on the side surface. The array-type lead frame is divided along the cutting path to form multiple individual units; The coil support with the coil is fixed to the first surface of the unit, and the lead end of the coil is electrically connected to the coil connection part; The magnetic circuit system and the vibration system are assembled on the side of the coil support away from the packaging substrate; And fixing the top cover to one side of the first surface of the encapsulation substrate to form an electromagnetic acoustic module as described in any one of claims 1 to 5.

10. The manufacturing method according to claim 9, characterized in that, The step of fixing the chip to the chip carrier includes: attaching the chip to the chip carrier using an adhesive material.

11. The manufacturing method according to claim 9, characterized in that, Electrically connecting the lead end of the coil to the coil connection part includes: welding the lead end of the coil to the open-window welding area of ​​the coil connection part by spot welding process.

12. The manufacturing method according to claim 11, characterized in that, Before spot welding the lead end of the coil to the open-window welding area of ​​the coil connection part, the process further includes: Acquire a surface image of the first surface of the monomer; The boundary contour of the windowed welding area of ​​the coil connection is determined based on the surface image; the position data of the bonding wire recorded before the molding encapsulation is obtained, and the projection boundary of the area where the bonding wire is located in the plane perpendicular to the thickness direction of the encapsulation substrate is determined based on the position data. Multiple candidate spot welding positions are generated within the window-type welding zone.

13. The manufacturing method according to claim 12, characterized in that, Also includes: For each of the candidate spot welding positions, calculate the first distance from the candidate spot welding position to the projected boundary and the second distance to the boundary profile; Select the target spot welding position from the candidate spot welding positions where the first distance is greater than the first preset threshold and the second distance is greater than the second preset threshold.

14. The manufacturing method according to claim 12, characterized in that, The generation of multiple candidate spot welding positions within the window-type welding area includes: Obtain the local curvature of each boundary point on the boundary profile; Boundary points with local curvature greater than the curvature threshold and their regions within a preset range are marked as boundary anomaly regions. The candidate spot weld location is generated in the area outside the boundary abnormal region of the windowed welding zone.

Images