METHOD FOR ESTABLISHING ELECTRICAL CONNECTION, CAMERA MODULE AND ELECTRONIC DEVICE HAVING THE CAMERA MODULE

A method for electrical connection is presented, including preparing a pre-bonding assembly with a first and second connection pad and an insulating layer, where the first pad includes two sections, with the second staggered and covered by the insulating layer. An activatable conductive film, filled with isolated conductive particles, is placed between the first pad's section and the second pad. Upon pressing, the film activates, extending into the insulating layer, connecting the first section and second pad electrically, while isolating the second section. This provides a reliable connection, suitable for camera modules and other electronics.

FIELD

The subject matter herein generally relates to electrical connection in electronic devices, and more particularly, to a method for establishing electrical connection, a camera module assembled using the method, and an electronic device having the camera module.

BACKGROUND

Anisotropic conductive films (ACFs) are generally composed of polymer-based matrix with conductive fillers such as metallic particles or metal-coated polymer spheres. The ACFs can provide unidirectional electrical conductivity in the vertical direction. A camera module may use the ACF to connect pads of a flexible board to a lens.

However, when heat and pressure are applied to the ACFs, the conductive fillers may become unevenly distributed in the ACFs, leading to potential signal interference among the pads. The signal interference can degrade the performance of electronic circuits and, in worse cases, affect the overall reliability and functionality of camera module.

DETAILED DESCRIPTION

Referring to FIG. 1, an embodiment of the present application provides a method for establishing electrical connection in camera assembly. In other embodiments, the method could be applied in various scenarios requiring electrical connections, such as among LEDs and control circuits in displays, automotive dashboards, medical devices, and other display systems. The method is provided by way of example, as there are a variety of ways to carry out the method. Each block shown in FIG. 1 represents one or more processes, methods, or subroutines, carried out in the example method. Furthermore, the illustrated order of blocks is illustrative only and the order of the blocks can change. Additional blocks can be added, or fewer blocks may be utilized or the order of the blocks may be changed, without departing from this disclosure. The method can begin at block S1.

Block S1, referring to FIGS. 2 and 3, a pre-bonding assembly 10 is provided. The pre-bonding assembly 10 includes a first connection pad 11, a second connection pad 12, and an insulating layer 13. The first connection pad 11 includes a first section 111 corresponding to the second connection pad 12 and a second section 112 connected to the first section 111. The first section 111 is spaced apart from the second connection pad 12. The second section 112 is staggered relative to the second connection pad 12. The insulating layer 13 covers the second section 111. The insulating layer 13 includes materials such as aluminum oxide (Al2O3), silicon dioxide (SiO2) for oxide layers, and polyimide, polytetrafluoroethylene (PTFE), or polyethylene (PE).

In this embodiment, the pre-bonding assembly 10 further includes a circuit board assembly 20 and a lens assembly 30. The circuit board assembly 20 includes a first body 21 with the first connection pad 11. The first connection pad 11 is arranged on an outer surface of the first body 21. The lens assembly 30 includes a second body 31 with the second connection pad 12. The second connection pad 12 is arranged on an outer surface of the second body 31. The first section 111 is configured to face the second connection pad 12.

In this embodiment, the first body 21 includes a flexible board 211, which includes a base layer 211a and a conductive structure 211b embedded within the base layer 211a. The first connection pad 11 is formed on one side of the base layer 211a facing the second body 31. The first connection pad 11 is connected to the conductive structure 211b. The insulating layer 13 is formed on the base layer 211a. The insulating layer 12 covers the second section 112 and electrically isolate the second sections 112 from ambient condition. The insulating layer 13 defines an opening 131. The first section 111 of the first connection pad 11 is exposed from the opening 131. The base layer 211a is made of polyimide. In other embodiments, the first body 21 may be a rigid board or a combination of rigid and flexible boards.

In this embodiment, the second body 31 includes a lens component 311, a voice coil motor 312, an image stabilization unit 313, an image sensor 314, and a bracket 315. The lens component 311 is connected to one side of the voice coil motor 312. The bracket 315 is connected to the other side of the voice coil motor 312. The image stabilization unit 313 is connected to the bracket 315. The bracket 315 defines a through hole 315a, and the image sensor 314 is disposed on the through hole 315a.

The lens component 311 can converge and guide light to the image sensor 314. The voice coil motor 312 can control the movement of the lens component 311 for rapid and precise focusing. The image stabilization unit 313 can adjusts the position of the image sensor 314 to counteract minor movements or vibrations, thereby enhancing image quality.

The image stabilization unit 313 and the bracket 315 extend beyond an edge of the voice coil motor 312 to form a connection portion 313a. The connection portion 313a is electrically connected to the voice coil motor 312. The second connection pad 12 are arranged on a surface of the connection portion 313a facing the first body 21, allowing for electrical connection between the second connection pad 12 and the first connection pad 11, thereby establishing electrical connection between the second body 31 and the first body 21.

Block S2, referring to FIG. 4, an activatable conductive film 40 is disposed between the first connection pad 11 and the second connection pad 12. The activatable conductive film 40 includes a plurality of conductive particles 41 and an adhesive 42. The conductive particles 41 are dispersed within the adhesive 42. The conductive particles 41 are electrically isolated from each other, so that the activable conductive film 40 is electrically insulated as a whole. The conductive particles 41 is made from materials like gold (Au), nickel (Ni), nickel/gold (Ni/Au), silver (Ag), or copper (Cu). The adhesive 42 is a thermosetting resin such as epoxy resin, polyimides, or phenolic resin.

Block S3, referring to FIGS. 4, 5, and 6, the first connection pad 11, the second connection pad 12, and the activatable conductive film 40 are pressed together to obtain a camera module 100. The pressing action transforms the activatable conductive film 40 into an activated conductive film 43. The activated conductive film 43 is connected between the first section 111 and the second pad 12. A portion of the activated conductive film 40 extends onto the insulating layer 13. The conductive particles 41 are interconnected to each other to form a conductive pathway 411. The conductive pathway 411 establishes an electrical connection between the first section 111 and the second pad 12. The insulating layer 13 electrically isolates the conductive pathway 411 from the second section 112, thereby insulating the second section 112 and the second conductive pad 12.

In this embodiment, heat is applied to the adhesive 42 of the activatable conductive film 40, causing the adhesive 42 to be cured to form a bonding matrix 44. The bonding matrix 44 defines a thickness A1 direction. The conductive particles 41 are in contact with each other along the thickness direction A1 to form the conductive pathway 411 inside the bonding matrix 44, thereby establishing electrical connection between the first section 111 and the second connection pad 12.

In this embodiment, referring to FIGS. 5 and 6, the block S3 further includes:

Block S31, referring to FIG. 5, a heat press machine 50 is provided, and the heat press machine 50 includes a base 51 and a heating head 52. The base 51 is used for supporting the lens assembly 30. The heating head 52 is used for applying pressure and heat to the circuit board assembly 20.

Block S32, referring to FIGS. 5 and 6, the pre-bonding assembly 10 and the activatable conductive film 40 are both placed between the base 51 and the heating head 52. The second body 31 is supported by the base 51. The first body 21 faces the heating head 52. The activatable conductive film 40 is disposed between the first connection pad 11 and the second connection pad 12.

Block S33, referring to FIG. 6, the heating head 52 moves towards the base 51 and applies a pressure force onto the first body 21. The base 51 applies another pressure force onto the second body 31. Both pressure forces transform the activatable conductive film 40 into the activated conductive film 43. Meanwhile, heat transferred from the heating head 52 to the activatable conductive film 40 and cures the adhesive 42 into the bonding matrix 44.

In this embodiment, referring to FIGS. 5 and 6, the block S3 further includes:

Block S34, referring to FIG. 6, a first cushioning pad 45 is disposed between the heating head 52 and the second body 31, and a second cushioning pad 46 is disposed between the base 51 and the first body 21. The first cushioning pad 45 and the second cushioning pad 46 can stabilize the pre-bonding assembly 10, and evenly distribute the pressure and heat to the activatable conductive film 40. In this embodiment, the first cushioning pad 45 is made of silicone, and the second cushioning pad 46 is made of rubber or polyurethane.

The method provided by this application employs the insulating layer 13 on the second section 112 of the first connection pad 11, and then pressing the first connection pad 11, the second connection pad 12, and the activatable conductive film 40. The method can minimize the risk of short circuits between the second section 112 and the second connection pad 12 during the pressing process. The insulating layer 13 not only isolates the second section 112 from the second connection pad 12, but also reduces the susceptibility of the camera module 100 to external electrostatic influences and signal interference, thereby enhancing the overall reliability of the camera module 100.

Referring to FIG. 6, a camera module 100 is provided according to an embodiment of the application. The camera module 100 includes a circuit board assembly 20, a lens assembly 30, and an activated conductive film 43. The circuit board assembly 20 includes a first connection pad 11, and the first connection pad 11 includes a first section 111 and the second section 112. The second section 112 is covered by an insulating layer 13. The lens assembly 30 comprises a second connection pad 12, which corresponds to the first section 111 and staggered from the second section 112. The activated conductive film 43 is connected between the first section 112 and the second connection pad 12. The activated conductive film 43 includes a bonding matrix 44 and a conductive pathway 411 within the boding matrix 44. The conductive pathway 411 is electrically connected between the first section 111 and the second connection pad 12. The insulating layer 13 electrically isolates the second section 112 from the second connection pad 12.

Referring to FIG. 7, an electronic device 200 is provided according to an embodiment of this application. The electronic device 200 includes the camera module 100 and a casing 201. The camera module 100 is partially exposed on the casing 201. The electronic device 200 may be a smartphone, tablet, or smartwatch with camera functionality.