Camera module and method of manufacturing the same

A camera module includes : a housing in which a lens barrel is accommodated; a circuit board fixedly mounted on a lower portion of the housing; and a guide member guiding a fixing position of the housing fixed to the circuit board, wherein the guide member includes a solder ball, formed on the circuit board to protrude in an upward optical axis direction and a guide groove, provided as a groove recessed in the upward optical axis direction in a lower end portion of the housing and into which the solder ball is fitted.

BACKGROUND

The present disclosure relates to a camera module and a method of manufacturing the same.

2. Description of Related Art

Recently, in accordance with the trend for miniaturization and slimness in mobile devices, including cellular phones, it has become important, in the industry, to reduce the sizes of components mounted in mobile devices, and high integration technology has been applied in order to exert a further improved function, together with the miniaturization of components mounted in mobile devices.

Particularly, camera modules adopted in current mobile devices, and the like, have been used in camera phones, personal digital assistants (PDAs), smartphones, laptop computers, and the like, and thus need to have a small size and a high performance image capturing function in accordance with consumer preference.

In more detail, mobile devices such as cellular phones, laptop computers, or the like, have recently been provided with camera modules in which an image capturing element such as a charge coupled device (CCD) image sensor, a complementary metal oxide semiconductor (CMOS) image sensor, or the like, is mounted, and the camera modules as described above have performance similar to that of a general high specification digital camera in accordance with an increase in the number of pixels and improvements in functions thereof.

In such a trend, alignment of a housing and a board constituting the camera module is adjusted by coupling a protrusion and a groove structure, in a process of coupling the housing and the board to each other. However, in such an alignment structure, a manufacturing tolerance or an assembly tolerance is easily generated due to a mechanical coupling structure, and a hole needs to be formed in the board, so that rigidity of the board and utilization of the board may thus be decreased.

SUMMARY

An aspect of the present disclosure may provide a camera module in which coupling alignment of a housing and a board may be improved without forming a hole in the board.

According to an aspect of the present disclosure, a camera module may include: a housing in which a lens barrel is accommodated; a circuit board fixedly mounted on a lower portion of the housing; and a guide member guiding a fixing position of the housing fixed to the circuit board, wherein the guide member includes a solder ball, formed on the circuit board to protrude in an upward optical axis direction and a guide groove, provided as a groove recessed in the upward optical axis direction in a lower end portion of the housing and into which the solder ball is fitted.

According to another aspect of the present disclosure, a method of manufacturing a camera module may include: forming a solder pad on a circuit board; disposing a passive component on the circuit board and applying a solder paste to the solder pad; performing a reflow process on the solder paste; and forming a solder ball from the solder paste and disposing a housing on the circuit board so that a guide groove is disposed in a portion corresponding to a position of the solder ball.

DETAILED DESCRIPTION

FIG. 1is a perspective view illustrating a camera module according to an exemplary embodiment in the present disclosure,FIG. 2is an exploded perspective view illustrating the camera module according to an exemplary embodiment in the present disclosure from which a circuit board is separated,FIG. 3is an assembled cross-sectional view illustrating the camera module according to an exemplary embodiment in the present disclosure, andFIG. 4is a cross-sectional view illustrating a housing of the camera module according to an exemplary embodiment in the present disclosure.

A camera module100according to an exemplary embodiment in the present disclosure may include a housing110in which a lens barrel111is accommodated and a circuit board130coupled to a lower portion of the housing110. In addition, the housing110and the circuit board130may be bonded and coupled to each other by an adhesive such as a thermosetting adhesive, an ultraviolet (UV) adhesive, or the like.

An inner portion of the housing110may have a hollow shape, and the lens barrel111including at least one lens stacked in an optical axis direction, an actuator performing an autofocusing (AF) function) by driving of the lens barrel111in the optical axis direction, an actuator performing an optical image stabilizer (OIS) function by driving the lens barrel111in a direction perpendicular to the optical axis direction, an optical filter116, and the like, may be accommodated in the housing110.

In addition, an image sensor137, various passive elements, and the like, maybe mounted on the circuit board130.

The lens barrel111may include a plurality of lenses embedded therein, capture an image of a subject with the image sensor137in the camera module100, and may be screwed to the housing110by a screw thread formed on an outer circumferential surface thereof.

The housing110may generally support the lens barrel111, may protect the lens barrel111from external impacts, and may be fixedly coupled to the circuit board130to protect a component mounted on the circuit board130, for example, the optical filter116such as an infrared (IR) filter, or the like.

Here, a screw groove engaged with the screw thread of the lens barrel111may be formed in an inner circumferential surface of a portion of the housing110to which the lens barrel111is coupled.

The optical filter116may be required in order to remove light wavelengths in an infrared region. In more detail, a camera of a camera phone converts light signals into electrical signals using a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) to form an image, and these light signals are sensed in an infrared region (up to 1150 nm) as well as a visible region (400 to 700 nm) that is visible to the human eye, such that signals unrelated to actual colors or images saturate a sensor. Therefore, an infrared (IR)-cut filter may be required in order to remove the light wavelengths in the infrared region.

The image sensor137may convert external images into electrical signals and store the electrical signals, and may store the external images instead of an existing film. The image sensor may be divided into a CCD and a CMOS image sensor (CIS). Here, the CCD may be a charge coupled device. In addition, the CIS may use a complementary metal oxide semiconductor (CMOS).

The circuit board130may be mounted on the lower portion of the housing110, and may have electrical circuits, various passive elements, and an integrated circuit mounted thereon in order to transmit and receive electrical signals.

The circuit board130may be fixedly coupled to the lower portion of the housing110. In addition, in a process of coupling the housing110and the circuit board130to each other, the housing110and the circuit board130need to be aligned with each other so that optical axes of the lenses stacked in the lens barrel111accommodated in the housing110and the center of the image sensor137mounted on the circuit board130coincide with each other, and then fixedly coupled to each other. In other words, the housing110and the circuit board130need to be fixedly coupled to each other in a state in which they are aligned with each other on the basis of a predetermined position.

Therefore, the camera module100according to the present disclosure may include guide members in order to align the housing110and the circuit board130with each other. The guide members may include solder balls135provided on the circuit board130and guide grooves113provided in the housing110.

In addition, at least two guide members may be provided along a circumference of a lower end portion of the housing. The camera module100according to the present exemplary embodiment illustrated in the drawings may have a rectangular shape, and as an example, the guide grooves113may be provided, respectively, in corner portions of the housing110having a rectangular shape, and the solder balls135may be provided on the circuit board130to correspond to the guide grooves113, such that four guide members may be provided in the camera module100.

The guide grooves113may be provided as grooves recessed in an upward optical axis direction in the lower end portion of the housing110, and the solder balls135may naturally align the housing110and the circuit board130with each other while being fitted into the guide grooves113in the process of coupling the housing110and the circuit board130to each other.

After the housing110and the circuit board130are aligned with each other by the solder balls135and the guide grooves113, a process of pressing the housing110and the circuit board130to each other may be additionally required in order to bond the housing110and the circuit board130to each other by an adhesive. Therefore, upper portions of the solder balls135may be pressed by the guide grooves113, such that shapes of the upper portions of the solder balls135may be changed depending on shapes of the guide grooves113.

The guide groove113may have a conical shape or a polygonal pyramid shape of which a sharp portion is directed in the upward optical axis direction. Therefore, the guide groove113may have a diameter that becomes small from the bottom toward the top, and the housing110and the circuit board130may thus be aligned with each other in a predetermined position while the center of the guide groove113and the center of the solder ball135are naturally aligned with each other in a process of fitting the solder ball135into the guide groove113.

The solder ball135may be formed on the circuit board130to protrude in the upward optical axis direction. The solder ball135may be naturally formed in a reflow process for soldering the passive elements, the image sensor137, and the like, mounted on the circuit board130.

That is, when the passive elements, the image sensor137, and the like, are mounted on the circuit board130, solder pads131are formed at positions at which the solder balls135are to be formed, solder pastes (solder creams)133are applied onto the solder pads131, and the reflow process is then performed, the solder balls135may be naturally formed while the solder pastes133being melted and hardened. In this case, the solder balls135may be easily formed without performing a separate additional process.

In addition, the solder ball135formed as described above may basically have a spherical shape, but a seated portion of the solder ball135seated on the circuit board130may have an approximately circular shape. Therefore, the solder ball135may have a dome shape, and a height of the solder ball135in the optical axis direction may be greater or smaller than a radius of the solder ball135and be smaller than a diameter of the solder ball135. The solder ball135has a spherical shape in a melted state, but may also be hardened in a slight flat spherical shape, that is, an egg shape, by force acting downwardly due to gravity, or the like. In this case, the seated portion of the solder ball135may have an approximately oval shape.

Meanwhile, the solder pads131may be applied to the circuit board130in order to form the solder balls135. The solder pad131may be formed of a metal, and may have a shape in which copper, nickel, gold, and the like, are stacked.

In addition, a shape in which the center of the solder pad131is aligned with the center of the guide groove113of the housing110may be the most accurate alignment shape.

The solder pad131may have an approximately circular shape, and may have a size smaller or equal to a diameter of the seated portion of the solder ball135. In other words, when the solder paste133applied onto the solder pad131is melted, a spherical liquid-state ball may be formed, and the solder ball135may be formed while the spherical liquid-state ball is hardened. In general, the solder pad131and the spherical liquid-state ball need to be disposed in a state in which the center of the solder pad131and the center of the spherical liquid-state ball coincide with each other, in order to accurately align the solder ball135and the guide groove113with each other. That is, the solder ball135may be formed to cover the entirety of the solder pad131.

To this end, a size of the solder pad131and an amount of applied solder paste133may be adjusted so that the solder pad131has the size smaller than or equal to the diameter of the seated portion of the solder ball135. Since the solder pad131and an upper surface of the circuit board130on which the solder pad131is provided have different properties, only when the solder paste133is applied around the solder pad131, the solder ball135may be basically formed naturally on the basis of the center of the solder pad131in a process of melting and hardening the solder paste133.

For example, when considering a case in which the solder pad131is externally exposed after the solder ball135is formed, since the solder pad131is very large, in a case opposite to the case described above, since the solder ball135is formed on an upper surface of the solder pad131having properties that are generally the same as that of the solder ball135, the solder pad131and the solder ball135may not be disposed in a state in which the center of the solder pad131and the center of the solder ball135are aligned with each other, and the solder ball135may be formed on any position of the upper surface of the solder pad131. Therefore, alignment between the housing110and the circuit board130may become impossible.

FIG. 5is views illustrating wafer-level and dice-level circuit boards used to manufacture the camera module according to an exemplary embodiment in the present disclosure,FIG. 6is a view illustrating a dice-level circuit board used to manufacture the camera module according to an exemplary embodiment in the present disclosure,FIG. 7is a view illustrating a shape in which a solder paste is applied to the dice-level circuit board used to manufacture the camera module according to an exemplary embodiment in the present disclosure, andFIG. 8is a view illustrating a shape in which the solder paste applied to the circuit board used to manufacture the camera module according to an exemplary embodiment in the present disclosure is subjected to a reflow process to form a solder ball.

Referring toFIG. 5, a circuit board used to manufacture the camera module according to the exemplary embodiment in the present disclosure may be a wafer-level circuit board120. That is, both of a process of mounting the passive components and the image sensors and a process of forming the solder balls may be performed on an integrated circuit board including a plurality of circuit boards each used in a single camera module100. Then, the integrated circuit board may be diced into dice-level circuit boards130to individually provide the dice-level circuit boards130, and the dice-level circuit board130may then be coupled to a single housing110.

Referring toFIG. 6, the dice-level (single) circuit board130used in the camera module according to the exemplary embodiment in the present disclosure is illustrated. It may be seen fromFIG. 6that the solder pads131are provided at corner portions of the dice-level circuit board130having a rectangular shape.

Referring toFIG. 7, it may be seen that the solder paste133is applied to the circuit board130used in the camera module according to the exemplary embodiment in the present disclosure, and it may be seen that the solder paste133is sufficiently applied so that the diameter of the seated portion of the solder ball135is greater than the solder pad131.

Referring toFIG. 8, an example of the solder ball135formed on the circuit board130is illustrated.

FIG. 9is a flow chart illustrating a method of manufacturing a camera module according to an exemplary embodiment in the present disclosure.

Referring toFIG. 9, the method of manufacturing a camera module according to an exemplary embodiment in the present disclosure may include forming the solder pad on the circuit board, disposing the passive component on the circuit board and applying the solder paste to the solder pad, performing the reflow process on the solder paste, and forming the solder ball from the solder paste and disposing the housing on the circuit board, the housing including the guide groove formed at a portion corresponding to a position of the solder ball.

Here, the method of manufacturing a camera module may further include, before the disposing of the housing on the circuit board, applying an adhesive to a lower end portion of the housing or an upper portion of the circuit board, and may further include, after the disposing of the housing on the circuit board, pressing and bonding the housing and the circuit board to each other.

Here, the circuit board may be a wafer-level circuit board, and in coupling the housing to the circuit board, the circuit board may be diced into a dice-level circuit board.

In addition, the guide groove may have the conical shape or the polygonal pyramid shape of which the sharp portion is directed in the upward optical axis direction. Therefore, when the housing is disposed on the circuit board so that the guide groove is disposed on the portion corresponding to the position of the solder ball, the center of the solder ball and the center of the guide groove may be naturally aligned with each other.

In addition, the pressing and bonding of the housing and the circuit board to each other, the upper portion of the solder ball may be pressed by the guide groove of the housing, such that the shape of the upper portion of the solder ball may be changed.

As set forth above, according to the exemplary embodiment in the present disclosure, coupling alignment of the housing and the circuit board may further be improved using a process necessarily included in processes of manufacturing the camera module.

According to the exemplary embodiment in the present disclosure, a hole does not need to be formed in the circuit board, and rigidity of the circuit board and utilization of the circuit board may thus be improved.