TW202429962A - Camera module packaging structure - Google Patents

Abstract

The present application provides a camera module packaging structure, including a flexible circuit board, an embedded printed circuit board, and a camera module with chip scale package. The present application adopts a no-flow underfill, which simplifies the process flow, and the thermal curing time of the no-flow underfill is short, which is conducive to protecting semiconductor components and improving service life. In addition, the no-flow underfill can be used for the reflow step, and the application scope is wider. The present application can form a stable structure of vertical conduction and horizontal insulation between the camera module with chip scale package and the flexible circuit board by setting anisotropic conductive film.

Description

Camera module packaging structure

This application relates to a camera module packaging structure.

The core technology of camera module processing is packaging technology. There are currently four mainstream packaging technologies, namely CSP (Chip Scale Package), COB (Chip on Board), COF (Chip on FPC) and FC (Flip Chip). In CSP, a ball grid array (BGA) is generally made after the circuit is extended on the back of the wafer. The advantages of CSP include that the chip size after packaging is equivalent to the grain size, which is suitable for application in portable electronic products (such as mobile phones, etc.).

Underfill (a chemical glue whose main component is epoxy resin) is now widely used on the back of the BGA chip to improve the reliability of the chip when it falls after being soldered to the circuit board. However, the existing underfill process is too cumbersome and lengthy, and requires a lot of equipment.

In view of this, this application proposes a camera module packaging structure to simplify the process flow.

An embodiment of the present application provides a camera module packaging structure, which includes:

Flexible circuit board;

an embedded printed circuit board, the embedded printed circuit board being electrically connected to the flexible circuit board via anisotropic conductive glue; and

A chip-level packaged camera module is arranged on a side of the embedded printed circuit board away from the flexible circuit board, and the chip-level packaged camera module is connected to the embedded printed circuit board through a non-flowing bottom filler.

In one embodiment, the no-flow underfill includes flux and underfill.

In one embodiment, the underfill comprises epoxy.

In one embodiment, the chip-level package camera module includes a substrate, a photosensitive chip, an infrared filter and a packaging part. The substrate includes a first surface and a second surface arranged opposite to each other, and the photosensitive chip is arranged on the first surface. The packaging part is arranged on the first surface and covers the photosensitive chip, and the infrared filter is arranged on the packaging part and arranged opposite to the photosensitive chip.

In one embodiment, a ball grid array is disposed on the second surface of the substrate.

In one implementation, the wafer-level package camera module further includes a passive element. The passive element is disposed on the first surface and is covered by the packaging portion.

In one implementation, the wafer-level package camera module further includes a lens unit disposed on the packaging portion, and the lens unit includes a lens and a voice coil motor.

In one implementation, the photosensitive chip includes a photosensitive area and a non-photosensitive area, and the infrared filter is arranged opposite to the photosensitive area.

In one implementation, the photosensitive chip is electrically connected to the substrate via metal wires.

In one implementation, the material of the packaging portion includes curing glue.

This application uses a non-flowing bottom filler, which acts as a flux in the early stage and is converted into an adhesive for bottom filling in the reflow furnace. The reflow process can simultaneously complete solder ball welding and curing of the non-flowing bottom filler. Since the steps of applying flux and removing flux are omitted, the process flow is simplified, and the thermal curing time of the non-flowing bottom filler is short, which is beneficial to protect semiconductor components and improve their service life. In addition, the non-flowing bottom filler can be used in the reflow step, and has a wider range of applications. Moreover, by providing anisotropic conductive glue, this application can form a stable structure with vertical conduction and lateral insulation between the chip-level packaged camera module and the flexible circuit board.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present application embodiments. The terms used herein are only for the purpose of describing specific implementations and are not intended to limit the present application embodiments.

It will be understood that when a layer is referred to as being “on” another layer, it can be directly on the other layer or intervening layers may be present therebetween. In contrast, when a layer is referred to as being “directly on” another layer, there are no intervening layers.

Embodiments of the present application are described herein with reference to cross-sectional views, which are schematic illustrations of idealized embodiments (and intermediate configurations) of the present application. As such, variations in the shapes illustrated due to manufacturing processes and/or tolerances are to be expected. Therefore, embodiments of the present application should not be construed as limited to the specific shapes of the regions illustrated herein, but should include deviations in shapes resulting, for example, from manufacturing. The regions illustrated in the figures are schematic in themselves, their shapes are not intended to illustrate the actual shapes of the devices, and are not intended to limit the scope of the present application.

The following is a detailed description of some implementations of the present application in conjunction with the attached drawings. In the absence of conflict, the following implementations and features in the implementations can be combined with each other.

Referring to FIG. 1 and FIG. 2 , an embodiment of the present application provides a camera module package structure 100, which includes a flexible circuit board 10, an embedded printed circuit board 30, and a wafer-level packaged camera module 50. The embedded printed circuit board 30 is electrically connected to the flexible circuit board 10 through an anisotropic conductive adhesive 20. The embedded printed circuit board 30 refers to a structure in which the passive components (i.e., passive components, such as capacitors, resistors, etc.) thereon are embedded into the circuit board, so that the size of the circuit board can be reduced, which is conducive to reducing the size of the overall camera module package structure 100. The WLP camera module 50 is disposed on a side of the embedded printed circuit board 30 away from the flexible circuit board 10 , and the WLP camera module 50 is connected to the embedded printed circuit board 30 via a non-flowing bottom filler 40 .

The application principle of underfill is to use the capillary action to make the glue flow quickly through the bottom of the BGA chip, thereby filling the bottom of the BGA chip, and then using heat to cure the glue to fill a large area of the BGA bottom gap (generally covering more than 80%) to achieve the purpose of reinforcement and enhance the anti-drop performance between the BGA chip and the circuit board connected to it. The bonding process of the underfill is generally: applying flux, hot pressing, removing flux, applying underfill, hot pressing, etc. This application uses a non-flow underfill 40, which acts as a flux in the early stage and is converted into an adhesive in the reflow furnace for underfilling. The non-flow bottom filler 40 can be applied before solder ball placement, and the reflow process can simultaneously complete solder ball bonding and curing of the non-flow bottom filler 40. Since no flux is required, the steps of applying and removing the flux can be omitted, thereby simplifying the process flow. The non-flow bottom filler 40 has a short thermal curing time, which is beneficial to protecting semiconductor components and improving their service life. In addition, the non-flow bottom filler 40 can be used in the reflow step, and has a wider range of applications.

Anisotropic Conductive Film (ACF) is a combination of high-quality resin and conductive particles. It is mainly used to connect substrates and circuits that need to be connected to each other. It has the characteristics of vertical electrical conduction (Z axis) and insulation in the left and right planes (X and Y axes), and has excellent moisture-proof and bonding functions. ACF can be pressed by a bonding machine (temperature is about 150~200℃), but because there is also a reflow soldering process, the anisotropic conductive glue 20 described in this application needs to be selected to be an anisotropic conductive glue that can withstand high temperatures (above 250℃) and can withstand the furnace temperature of the reflow soldering (peak temperature is about 250~260℃). The present application forms a stable structure with vertical conduction and lateral insulation between the chip-level packaged camera module 50 and the flexible circuit board (FPC) 10 by providing anisotropic conductive adhesive 20, thereby solving the problem that components such as FPC cannot be connected to circuits by high-temperature lead-tin welding.

In some embodiments, the non-flowing bottom filler 40 includes a flux and a bottom filler. The flux may be a conventional or unconventional flux in the art, and the present application does not limit it. For example, the flux may be a flux containing an inorganic acid, the main components of which are hydrochloric acid, hydrofluoric acid, etc.; the flux may also be a flux containing an inorganic salt, the main components of which are zinc chloride, ammonium chloride, etc.

Furthermore, the bottom filler may be but is not limited to epoxy resin.

As shown in Fig. 2, in some embodiments, the wafer-level package camera module 50 includes a substrate 51, a photosensitive chip 52, an infrared filter 53 and a packaging part 54. The substrate 51 can be a printed circuit board (PCB) known in the art, and the substrate 51 includes a first surface 511 and a second surface 512 arranged opposite to each other.

The photosensitive chip 52 is disposed on the first surface 511 and is approximately located in the middle of the first surface 511. The photosensitive chip 52 is used to obtain external images, and can be specifically a CMOS (Complementary Metal Oxide Semiconductor) photosensitive chip.

Furthermore, the photosensitive chip 52 may include a photosensitive area 521 and a non-photosensitive area 522, wherein the photosensitive area 521 is approximately located in the middle of the photosensitive chip 52, and the remaining part constitutes the non-photosensitive area 522. The photosensitive chip 52 may be electrically connected to the substrate 51 via a metal wire 60. Specifically, one end of the metal wire 60 may be welded to a pad (not shown) of the non-photosensitive area 522 of the photosensitive chip 52, and the other end may be welded to a circuit of the substrate 51, thereby forming an electrical connection. The metal wire 60 may be, but is not limited to, a gold wire, a silver wire, etc.

The packaging part 54 is disposed on the first surface 511 and covers the photosensitive chip 52. It can be understood that the packaging part 54 also covers the metal wire 60, which is beneficial to prevent the metal wire 60 from breaking and oxidation. The infrared filter 53 is disposed on the packaging part 54 and is disposed opposite to the photosensitive chip 52. Specifically, the infrared filter 53 is disposed opposite to the photosensitive area 521 of the photosensitive chip 52.

In some embodiments, the infrared filter 53 is directly fixed on the packaging part 54, that is, when filling glue or injecting glue to form the packaging part 54, the infrared filter 53 is placed at a position corresponding to the upper part of the photosensitive area 521 of the photosensitive chip 52, and the infrared filter 53 is bonded to the packaging part 54 while the glue is solidified. That is, in some embodiments, the packaging part 54 is formed by curing the curing glue, and the curing glue can be but is not limited to ultraviolet curing glue, etc.

As shown in FIG. 2 , in some embodiments, the wafer-level package camera module 50 further includes a passive element 55. The passive element 55 is disposed on the first surface 511, approximately at the end region of the substrate 51. The passive element 55 is covered by the packaging portion 54, so that the passive element 55 is not easy to fall off. The passive element 55 may be, but is not limited to, components such as resistors and capacitors.

As shown in FIG2 , in some embodiments, the wafer-level package camera module 50 further includes a lens unit 56 disposed on the packaging portion 54. The lens unit 56 includes a lens 57 and a voice coil motor 58, and the lens unit 56 can be bonded to the surface of the packaging portion 54 away from the substrate 51 through the voice coil motor 58.

As shown in FIG1 and FIG2 , in some embodiments, a ball grid array (BGA) 70 is disposed on the second surface 512 of the substrate 51. Each solder ball in the ball grid array 70 can be interconnected with a printed circuit board (PCB) as an I/O terminal of the circuit.

This application adopts a no-flow underfill 40, which acts as a flux in the early stage and is converted into an adhesive for bottom filling in the reflow furnace. The reflow process can simultaneously complete the solder ball welding and the curing of the no-flow underfill 40. Since the steps of applying the flux and removing the flux are omitted, the process flow is simplified, and the thermal curing time of the no-flow underfill 40 is short, which is beneficial to protect semiconductor components and improve their service life. In addition, the no-flow underfill 40 can be used in the reflow step, and has a wider range of applications. Furthermore, the present application can form a stable structure with vertical conduction and lateral insulation between the wafer-level package camera module 50 and the flexible circuit board (FPC) 10 by providing anisotropic conductive adhesive 20.

The above descriptions are some specific implementations of this application, but in the actual application process, it cannot be limited to these implementations. For ordinary technical personnel in this field, other variations and changes made according to the technical concept of this application should all fall within the scope of protection of this application.

100: Camera module packaging structure 10: Flexible circuit board 30: Embedded printed circuit board 50: Wafer-level package camera module 20: Anisotropic conductive adhesive 40: Non-flowing bottom filler 51: Substrate 52: Photosensitive chip 53: Infrared filter 54: Package 55: Passive element 56: Lens unit 57: Lens 58: Voice coil motor 60: Metal wire 70: Ball grid array 511: First surface 512: Second surface 521: Photosensitive area 522: Non-photosensitive area

FIG1 is a schematic diagram of the exploded structure of a camera module packaging structure provided in an embodiment of the present application.

FIG. 2 is a schematic cross-sectional view of a wafer-level package camera module of the camera module package structure shown in FIG. 1 .

100: Camera module packaging structure

10: Flexible circuit board

20: Anisotropic conductive glue

30:Embedded printed circuit board

40: Non-flowing bottom filler

50: Chip-level package camera module

70: Ball and grid array

Claims (10)

A camera module packaging structure, the improvement of which is that it includes: a flexible circuit board; an embedded printed circuit board, the embedded printed circuit board and the flexible circuit board are electrically connected through anisotropic conductive glue; and a chip-level packaged camera module, the chip-level packaged camera module is arranged on a side of the embedded printed circuit board away from the flexible circuit board, and the chip-level packaged camera module and the embedded printed circuit board are connected through a non-flowing bottom filler. A camera module packaging structure as described in claim 1, wherein the non-flowing bottom filler includes flux and bottom filler. A camera module packaging structure as described in claim 2, wherein the bottom filler includes epoxy resin. A camera module packaging structure as described in claim 1, wherein the chip-level packaged camera module includes a substrate, a photosensitive chip, an infrared filter and a packaging unit; the substrate includes a first surface and a second surface arranged opposite to each other, the photosensitive chip is arranged on the first surface, the packaging unit is arranged on the first surface and covers the photosensitive chip, and the infrared filter is arranged on the packaging unit and arranged opposite to the photosensitive chip. A camera module packaging structure as described in claim 4, wherein a ball grid array is provided on the second surface of the substrate. The camera module packaging structure as described in claim 4, wherein the chip-level packaged camera module further includes a passive element, the passive element is disposed on the first surface, and the passive element is covered by the packaging portion. The camera module packaging structure as described in claim 4, wherein the chip-level packaged camera module further includes a lens unit disposed on the packaging portion, and the lens unit includes a lens and a voice coil motor. The camera module packaging structure as described in claim 4, wherein the photosensitive chip includes a photosensitive area and a non-photosensitive area, and the infrared filter is arranged opposite to the photosensitive area. A camera module packaging structure as described in claim 4, wherein the photosensitive chip is electrically connected to the substrate via metal wires. A camera module packaging structure as described in claim 4, wherein the material of the packaging part includes a curing glue.

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