Circuit module for voice coil motor

Abstract

The utility model provides a circuit module for a voice coil motor, which is characterized in that the circuit module comprises a circuit board, an electronic component and a coil are welded on the surface of the circuit board, and the electronic component and the surface of the circuit board where the electronic component is located are plastically packaged in a first injection molding layer. Through the integrated design, the circuit board, the electronic component, the coil and other key components are tightly combined in a small circuit module, the shell is formed through the injection molding process, and a traditional heavy base and support structure is replaced. By means of the innovation, maximum utilization of the internal space is achieved, all the assemblies can be compactly and orderly arranged, and more possibilities are provided for other assemblies or extended functions. Meanwhile, as the number of extra connectors and parts is reduced, the weight of the whole module is obviously reduced, the assembly process of the voice coil motor is simplified, and the production cost is also reduced.

Description

Technical Field

[0001] The utility model relates to a circuit module for a voice coil motor. Background Art

[0002] A voice coil motor (Voice Coil Motor) is a device that converts electrical energy into mechanical energy and can achieve linear and limited swing angle movement. In the camera of a smartphone, the voice coil motor is used to adjust the position of the lens to change the focal length and make the camera clearer. A common voice coil motor includes a housing, an upper gasket, a front reed, a coil, electronic components, a magnet, a bracket, a rear reed and a base. The housing and the base are matched together in an upper and lower manner, and other components are arranged inside the housing and the base. The bracket is usually a rectangular structure, and the coil is fixed on the periphery of the bracket. Various electronic components are also installed using the bracket as a carrier.

[0003] In order to meet the ultra-small volume requirements of voice coil motors for electronic devices with cameras such as smartphones, the applicant proposed an improved structure in the Chinese utility model patent "An OIS motor coil assembly and preparation method" with application number 202211331530.5 (application publication number CN 115549353 A) in 2022, which replaced the traditional structure of the coil sleeve on the bracket with a flat coil. Although the coil structure has been upgraded to a flat type to save space, the base and carrier parts of the voice coil motor, which account for the largest volume, have not yet been fully miniaturized. At the same time, most electronic components are still installed independently, which means that there is still room for optimization in improving the overall integration of audio motors and further reducing their volume. Utility Model Content

[0004] The technical problem to be solved by the present invention is to propose a highly integrated circuit module for a voice coil motor in view of the above technical status quo.

[0005] The technical solution adopted by the utility model to solve the above technical problems is: a circuit module for a voice coil motor, characterized in that it includes a circuit board, and electronic components and coils are welded on the surface of the circuit board, and the electronic components and the surface of the circuit board where the electronic components are located are plastic-encapsulated by a first injection molding layer.

[0006] Preferably, the electronic components are soldered to the same surface of the circuit board.

[0007] Specifically, the electronic components include capacitors, resistors, IC components and Hall sensors.

[0008] Furthermore, the coil is welded to another surface of the circuit board opposite to the surface where the electronic components are located.

[0009] To protect the coil and provide support, optionally, the coil and the surface of the circuit board where the coil is located are encapsulated by a second injection molding layer.

[0010] Specifically, the circuit board includes an intermediate insulating layer, and circuits located on the upper and lower surfaces of the intermediate insulating layer respectively. The circuit surface is also covered with a covering film. The covering film has windows where electronic components and coils need to be soldered. The circuit surface in the window area is formed with a soldering pad through surface treatment.

[0011] Preferably, the cover film is further provided with a window on the edge of the surface of the circuit board where the coil is located, and the circuit surface of the window area is also formed with a pad as a circuit board pin through surface treatment.

[0012] In order to make the overall strength of the circuit module higher, another optional solution can be adopted: the first injection molding layer and the second injection molding layer are plastic-sealed inside the circuit board, the electronic components and the coil, the first injection molding layer or the second injection molding layer has a blind hole, the bottom surface of the blind hole is the side surface or surface of the circuit board, and the pins of the circuit board are led out of the blind hole through the redistribution layer. Or: the bottom surface of the blind hole is the surface of the coil, and the pins of the circuit board are led out of the blind hole through the redistribution layer.

[0013] Specifically, the cover film includes a PI layer and AD glue, and the AD glue adheres the PI layer 8 to the circuit and fills the gaps between the circuit and between the circuit and the PI layer.

[0014] The utility model uses an integrated design to tightly combine key components such as circuit boards, electronic components and coils in a small circuit module, and uses injection molding to form the shell, replacing the traditional bulky base and bracket structure. This innovation not only maximizes the use of internal space, allowing the components to be arranged compactly and orderly, but also provides more possibilities for other components or expanded functions. At the same time, due to the reduction of additional connectors and parts, the weight of the entire module can be significantly reduced, which not only simplifies the assembly process of the voice coil motor, but also reduces production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figures 1 to 3 Schematic diagram of the manufacturing process of the first embodiment of the present utility model, wherein (a) to (n) correspond to S1 to S14 of the manufacturing process in sequence, and (n) is also a schematic diagram of the structure of the first embodiment;

[0016] Figures 4 to 7 Schematic diagram of the manufacturing process of the second embodiment of the present utility model, wherein (a) to (p) correspond to S1 to S16 in sequence, and (p) is also a schematic diagram of the structure of the second embodiment. DETAILED DESCRIPTION

[0017] The present invention will be described in further detail below in conjunction with the accompanying drawings.

[0018] Embodiment 1

[0019] like Figures 1 to 3 As shown, a preparation process of a circuit module for a voice coil motor and a preferred embodiment of the circuit module of the utility model are shown, and the preparation process specifically includes the following steps:

[0020] S1. Cutting the substrate: The substrate includes an intermediate insulating layer 1 and a conductor layer 2 covering the upper and lower surfaces of the intermediate insulating layer 1. In this embodiment, double-sided copper-clad FCC is selected as the substrate. The thickness of the substrate is designed according to product requirements, preferably 10 to 300 μm. The conductor layer 2 is made of copper, preferably 13 to 36 μm thick copper foil.

[0021] S2, drilling: drilling a via hole 3 on the surface of the substrate for subsequent connection of two layers of circuits on the upper and lower surfaces of the substrate. The drilling process can be mechanical drilling, laser drilling, die punching, laser blind hole drilling, etc. This embodiment takes mechanical drilling as an example for description.

[0022] S3, depositing a seed layer: depositing a seed layer 4 on the entire substrate as a transition layer for subsequent conductor addition. The process can be chemical deposition, vacuum coating, etc. The seed layer 4 can be made of titanium, copper, nickel, etc., or alloy layers of different metals. This embodiment takes copper as an example for description.

[0023] S4, electroplating: electroplating the entire substrate so that the surface of the substrate and the wall of the through hole 3 are both plated with the electroplating layer 5.

[0024] S5, lamination: laminating the upper and lower surfaces of the substrate and the through holes to form a dry film layer 6. The type and thickness of the photoresist to be selected should be based on the actual product design. This embodiment takes Hitachi RD1229 (29 μm thick pattern selective plating photoresist) as an example for description.

[0025] S6, exposure: exposing the circuit pattern area of ​​the dry film layer 6, so that the photoresist in the exposure area 6b of the dry film layer 6 is irradiated with light and fuses, so as to protect the circuit in the subsequent etching process.

[0026] S7, development: dissolving the unexposed area 6a of the dry film layer 6 to expose the conductor layer 2 in the non-circuit pattern area, while the exposed area 6b of the dry film layer 6 cannot be dissolved due to the drastic change of the photoresist.

[0027] S8, etching: using a metal etching solution corresponding to the conductor layer 2 to chemically etch the conductor layer 2 in the area not protected by the dry film layer 6, the remaining part of the conductor layer 2 after etching forms a circuit, and the etching process can be selected from ordinary etching, vacuum etching, two-fluid etching, etc.

[0028] S9, film removal: the remaining dry film layer 6 (i.e., the dry film layer 6 of the exposure area 6b) of the protective conductor layer 2 is removed, and the film removal solution can be selected from organic film removal solution, inorganic film removal solution, etc., and the corresponding film removal solution is selected according to the type of photoresist. The process steps of processing the circuit for the substrate are completed from S1 to S9.

[0029] S10, Laminating the covering film: Laminating the covering film on the surface of the circuit, and opening windows 15 at the positions where the electronic components 11 and the coils 12 need to be welded. The covering film is also opened at the edge of the upper surface of the circuit board, so that the circuit in this area can be used as the pin 14 of the circuit module after the subsequent surface treatment. The covering film is used to protect the outer surface and conductive pattern of the circuit board, prevent environmental factors from damaging the circuit, and also provide electrical insulation. The covering film includes a PI layer 8 and an AD glue 7, and its type and specifications are selected according to customer needs or designs.

[0030] S11, surface treatment, surface treatment is performed on the window 15 to form a circuit board with a pad 9. Common surface treatment processes include nickel-palladium-gold, gold plating, OSP, and double surface treatment. Gold plating is preferred for welding; nickel-palladium-gold is preferred for wire binding, and the specific selection is based on the customer's product design.

[0031] S12, welding electronic components 11: welding the electronic components 11 including capacitors 11a, resistors 11b, IC components 11c, Hall sensors 11d, etc. to the pads 9 on the lower surface of the circuit board, and forming a first injection molding layer 10 by injection molding, the first injection molding layer 10 encapsulates the electronic components 11. The first injection molding layer 10 can not only protect these electronic components 11, but also play the role of replacing the base.

[0032] S13, welding the coil 12: solder the coil 12 to the pad 9 on the upper surface of the circuit board through the SMT process. There are multiple optional welding schemes for this step, such as soldering the coil 12 to the circuit board through the through hole in the center of the coil 12 and the pad 9 of the circuit board; or soldering the coil 12 to the circuit board by forming the pad 9 on the surface of the coil 12 through surface treatment, and soldering the coil 12 to the circuit board between the pad 9 of the coil 12 and the pad 9 of the circuit board.

[0033] S14, injection molding and encapsulating the coil 12: Injection molding is performed on the upper surface of the circuit board to form a second injection molding layer 13, which is used to protect the coil 12 and provide support. During the injection molding, it is necessary to avoid the area where the pins 14 are located. This step can be performed according to the requirements or design.

[0034] The circuit module manufactured by the above steps S1 to S14 includes a circuit board, electronic components 11 and a coil 12 , as well as a first injection molding layer 10 and a second injection molding layer 13 .

[0035] The circuit board includes an intermediate insulating layer 1, and circuits located on the upper and lower surfaces of the intermediate insulating layer 1, respectively. The intermediate insulating layer 1 is provided with a conducting hole 3, and the hole wall of the conducting hole 3 has a seed layer 4 and a plating layer 5 formed after addition, which together realize the conduction of the upper and lower surface circuits. The circuit surface is also covered with a covering film, which includes a PI layer 8 and an AD glue 7. The AD glue 7 is used to bond the PI layer 8 to the circuit, and at the same time fills the gap between the circuits and between the circuit and the PI layer 8 to play an insulating role. The covering film has windows 15 in the areas where electronic components 11, coils 12 need to be soldered, and which need to be used as circuit board pins 14. The circuit surface in the window 15 area is formed with a soldering pad 9 through surface treatment, and the soldering pad 9 is used to connect with the electronic components 11, coils 12 and external electrical appliances.

[0036] The electronic components 11 include capacitors 11a, resistors 11b, IC components 11c, and Hall sensors 11d, etc., which are welded to the lower surface of the circuit board and encapsulated in the first injection molding layer 10. The coil 12 is welded to the pad 9 on the upper surface of the circuit board and encapsulated in the second injection molding layer 13. During the injection molding, the pin 14 area is avoided so that the pin 14 is exposed in the second injection molding layer 13.

[0037] Embodiment 2

[0038] This embodiment is another preferred embodiment of a preparation process of a circuit module for a voice coil motor and a circuit module of the utility model, and the difference from the first embodiment is that:

[0039] S10, pressing the cover film: pressing the cover film on the circuit surface, and opening windows 15 at the positions where the electronic components 11 and the coils 12 need to be welded. No windows 15 are left for the pins 14 at the edge of the circuit board.

[0040] S14, injection molding and encapsulating the coil 12: Injection molding is performed on the upper surface of the circuit board to form a second injection molding layer 13, which is used to protect the coil 12 and provide support. During the injection molding, the coil 12 and the upper surface of the circuit board are completely encapsulated in the second injection molding layer 13. This step can be performed according to demand or design.

[0041] In addition, this embodiment also includes the steps of:

[0042] S15, drilling blind holes 16: drilling blind holes 16 on the injection molding layer. There are multiple options for the positions of the blind holes 16. In this embodiment, the blind holes 16 are drilled on the upper surface of the injection molding layer to expose the pads 9 on the upper surface of the coil 12. The pads 9 serve as the bottom surface of the blind holes 16.

[0043] S16, Redistribution Layer (RDL): The circuit pins in the circuit module are led to the upper and lower surfaces or sides of the circuit module through the redistribution layer, and are led to suitable bumps or bonding pads according to the design or requirements. In this embodiment, the circuit pins are led to the upper surface of the coil 12 as pins 14 for connecting the circuit module to external electrical appliances.

[0044] The circuit module made by the above steps S1 to S16 is different from the circuit module made in Example 1 in that the circuit board, the electronic components 11 and the coil 12 are encapsulated by the first injection molding layer 10 and the second injection molding layer 13, and a blind hole 16 is opened on the upper surface of the second injection molding layer 13. The bottom surface of the blind hole 16 is the upper surface pad 9 of the coil 12, and the pin 14 is led out from the pad 9 and exposed to the second injection molding layer 13.

Claims

1. A circuit module for a voice coil motor, characterized in that: It includes a circuit board, on the surface of which electronic components and coils are welded, the electronic components and the surface of the circuit board where the electronic components are located are sealed inside by a first injection molding layer; the coil is welded to another surface of the circuit board opposite to the surface where the electronic components are located; the coil and the surface of the circuit board where the coil is located are sealed inside by a second injection molding layer.

2. The circuit module according to claim 1, characterized in that: The electronic components are welded on the same surface of the circuit board.

3. The circuit module according to claim 2, characterized in that: The electronic components include capacitors, resistors, IC components and Hall sensors.

4. The circuit module according to claim 3, characterized in that: The circuit board includes an intermediate insulating layer and circuits located on the upper and lower surfaces of the intermediate insulating layer respectively. The circuit surface is also covered with a covering film. The covering film has windows where electronic components and coils need to be soldered. The circuit surface in the window area is formed with a soldering pad through surface treatment.

5. The circuit module according to claim 4, characterized in that: The cover film also has a window on the edge of the surface of the circuit board where the coil is located, and the circuit surface in the window area is also formed with a pad as a circuit board pin through surface treatment.

6. The circuit module according to claim 4, characterized in that: The first injection molding layer and the second injection molding layer encapsulate the circuit board, electronic components and coils inside. The first injection molding layer or the second injection molding layer has a blind hole, the bottom surface of the blind hole is the side surface or surface of the circuit board, and the pins of the circuit board are led out from the blind hole through the redistribution layer.

7. The circuit module according to claim 4, characterized in that: The first injection molding layer and the second injection molding layer encapsulate the circuit board, electronic components and coils. The first injection molding layer or the second injection molding layer has a blind hole, the bottom surface of the blind hole is the surface of the coil, and the pins of the circuit board are led out from the blind hole through the redistribution layer.

8. The circuit module according to any one of claims 4 to 7, characterized in that: The covering film includes a PI layer and AD glue, and the AD glue adheres the PI layer to the circuit and fills the gaps between the circuit and between the circuit and the PI layer.

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