JP2004045592A - Observation device for spherical bodies - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an observation apparatus for spherical body which is made simplified and low-cost while securing a successful observation result by uniformizing illumination condition. <P>SOLUTION: In the observation apparatus for spherical body which observes a ball 3 arranged flatly on a substrate 2 like a lattice with a camera which is relatively transferred in a first direction relative to the substrate 2, an illumination unit which illuminates an imaging visual field 5 of the camera from the surroundings is constituted of a pair of longitudinal illumination unit 6A(F) and 6A(R) arranged along the imaging visual field so as to sandwich the imaging visual field in the front and rear direction relative to the first direction and a pair of lateral illumination units 6B(R) and 6B(L) arranged on the side of the imaging visual field 5 so as to sandwich the imaging visual field 5 in the right and left direction relative to the first direction and light intensity of light emitting elements 7 of each of lower part units 9, upper part units 10 of the lateral illumination units 6B(R), 6B(L) is set based on distance between the elements 7 and target illumination areas 5R and 5L. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a spherical body observation apparatus for optically observing a spherical body such as a conductive ball mounted for forming a bump of a semiconductor package.
[0002]
[Prior art]
A semiconductor package such as a BGA (Ball Grid Array) is provided with a metal bump which is a spherical projection electrode for connection to a substrate circuit. The metal bumps are formed by mounting and joining conductive balls (hereinafter, abbreviated as “balls”) such as solder balls on electrodes of a substrate constituting a package. After the balls are mounted on the board, an arrangement test is performed to check the arrangement state of the balls, that is, whether or not the balls are present and whether the ball positions are normal.
[0003]
Conventionally, this arrangement inspection is performed by optically observing a ball on the arrangement surface with a camera. When it is necessary to efficiently image a wider range as a camera for observation, a line camera having an elongated imaging field of view is used. In this method, an image of a ball on a substrate is acquired by sequentially capturing a plurality of images while relatively moving the substrate with respect to the line camera.
[0004]
[Problems to be solved by the invention]
In the ball arrangement inspection, it is necessary to acquire a good quality ball image in order to obtain good inspection accuracy. In order to obtain a high-quality image for a ball having a spherical metallic glossy surface, it is important to uniformly illuminate the ball surface. Therefore, when imaging a ball, generally, ring illumination is used in which a large number of light emitting elements are arranged in a circular ring shape so as to surround the imaging field of view from the surroundings. The size of the ring illumination device used for this illumination needs to be about three times as large as the size of the imaging field of view.
[0005]
However, when the above-described ring illumination is applied to imaging of a ball using the line camera, a ring illumination device having a large diameter is required. When the diameter of the ring illumination device increases, the distance to the illumination target increases, so that a light source with a higher light intensity is required. As described above, the conventional observation apparatus using a line camera requires a large-sized and large-amount illumination apparatus in order to realize uniform illumination conditions. However, there is a problem that it is difficult to simplify the equipment and reduce the cost.
[0006]
Therefore, an object of the present invention is to provide a spherical body observation apparatus capable of simplifying the equipment and reducing the cost while ensuring good observation results by making illumination conditions uniform.
[0007]
[Means for Solving the Problems]
2. The apparatus for observing a spherical body according to claim 1, wherein the apparatus for observing a plurality of spherical bodies arranged in a plane on a workpiece is a spherical body observing apparatus, and moves relative to the workpiece in a first direction. A camera having an elongated imaging field of view having a second direction orthogonal to the longitudinal direction as a longitudinal direction, and an illumination unit for illuminating the imaging field of view from the surroundings, wherein the illumination unit changes the imaging field of view from the front-back direction in the first direction. A pair of front-rear illuminating units disposed along the imaging field of view, and a pair of side illuminating units disposed laterally of the imaging field across the imaging field from the left and right in the first direction; And with.
[0008]
An apparatus for observing a spherical body according to claim 2 is the apparatus for observing a spherical body according to claim 1, wherein the side illumination unit includes a plurality of light-emitting elements corresponding to an illumination area in the imaging visual field. .
[0009]
An apparatus for observing a spherical body according to claim 3 is the apparatus for observing a spherical body according to claim 1, wherein the light intensity of the light emitting element is set based on a distance between the illumination area and the light emitting element. You.
[0010]
According to the present invention, a pair of front-back illumination units disposed along the imaging field with the illumination unit illuminating the elongated imaging field of view of the line camera sandwiching the imaging field from the front-back direction in the transport direction, By providing a pair of side illuminating units disposed on the side of the imaging visual field with the imaging visual field sandwiched from the left and right directions, a compact illuminating unit can be obtained while uniform illumination conditions are provided to ensure good observation results. As a result, the equipment can be simplified and the cost can be reduced.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an apparatus for observing a spherical body according to one embodiment of the present invention, FIG. 2 is a plan view of an illumination unit of the apparatus for observing a spherical body according to one embodiment of the present invention, and FIG. FIG. 3B is a cross-sectional side view of the illumination unit of the apparatus for observing a spherical body according to one embodiment of the present invention, and FIG. FIG. 4 is a cross-sectional view, FIG. 4 is a block diagram showing a configuration of a control system of an illumination unit in the spherical object observation apparatus according to one embodiment of the present invention, and FIGS. 5 and 6 are observations of a spherical object according to one embodiment of the present invention. It is explanatory drawing of the illumination method of the spherical body by the illumination part of an apparatus.
[0012]
First, an apparatus for observing a spherical body will be described with reference to FIG. As shown in FIG. 1, a spherical body observation device 1 includes a substrate 2 (work) on which a plurality of spherical solder balls 3 (hereinafter, abbreviated as “balls 3”) are mounted in a grid-like planar arrangement. Is the observation target. The substrate 2 is transported in a first direction (the direction of arrow a) in a horizontal plane by a substrate transport mechanism (not shown). In the process of moving the substrate 2 relative to the camera 4 disposed above the transport path, the camera 4 observes the ball mounting state on the substrate 2, and based on the observation result, the arrangement state of the balls 3. Is determined.
[0013]
The camera 4 is a line camera in which imaging pixels are arranged in series, and has an elongated imaging field of view 5 whose longitudinal direction is a second direction orthogonal to the first direction. In the process of transporting the substrate 2, the balls 3 on the substrate 2 are sequentially observed because the ball rows in the second direction are sequentially positioned in the imaging visual field 5. At this time, the imaging field of view 5 is illuminated by the illuminating unit 6 arranged so as to surround the periphery from four directions.
[0014]
Next, the configuration and function of the illumination unit 6 will be described with reference to FIGS. As illustrated in FIG. 2, the illumination unit 6 includes a pair of front-back illumination units 6A (F) and 6A (R) disposed along the imaging visual field 5 with the imaging visual field 5 sandwiched from the front-back direction in the first direction. ), And a pair of side illuminators 6B (R) and 6B (L) disposed on the side of the imaging visual field 5 with the imaging visual field 5 sandwiched from the left and right in the first direction.
[0015]
Each of the illumination units 6A (F) and 6A (R) in the front-rear direction has an illumination range wider than the longitudinal dimension of the imaging visual field 5, and as shown in FIG. The illumination light is emitted from the front and rear directions to the ball 3 located in the imaging field of view 5 by the plurality of light emitting elements 7 arranged on the side facing. As the light emitting element 7, a light emitting diode is used. Of the light reflected by the spherical surface of the ball 3 of the illumination light, the light reflected upward (see arrow b) enters the camera 4. As a result, as shown in FIG. 6A, in the image of the ball 3 as viewed in plan, a substantially arc-shaped bright portion 13 located only on the front-rear surface of the solder ball 3 is obtained.
[0016]
Each of the side lighting units 6B includes four lighting units 8, and each of the lighting units 8 is arranged at an angle at which the imaging visual field 5 is irradiated with illumination light from the side. As shown in FIG. 3B, the lighting unit 8 is composed of a lower unit 9 and an upper unit 10 each having a plurality of light emitting elements 7, and the lower unit 9, Illumination light from the light emitting element 7 of the upper unit 10 is emitted from both left and right directions. As the light emitting element 7, a light emitting diode is used.
[0017]
Therefore, the lateral illuminating portions 6B (R), 6B (L) are also provided on the left and right side surfaces of the solder ball 3 corresponding to the blind area of the illuminating light from the longitudinal illuminating portions 6A (F), 6A (R). 6A, the reflected light (see the arrow c) reflected upward from the spherical light of the ball 3 of the illumination light is incident on the camera 4 as in FIG. I do. As a result, as shown in FIG. 6B, in the image of the solder ball 3 in a plan view, an annular bright portion 14 in which the missing portion of the bright portion 13 in FIG. 6A is supplemented is obtained. The recognition of the solder bumps 3 is performed by detecting the annular bright portion 14.
[0018]
The lower unit 9 and the upper unit 10 each specify a target illumination area. The lower unit 9 of the right side illumination unit 6B (R) captures the right side 5R of the imaging visual field 5 and the upper unit 10 captures the image. The left side 5L of the visual field 5 is illuminated. Similarly, the lower unit 9 of the left side illumination unit 6B (L) illuminates the right region 5L of the imaging visual field 5 and the upper unit 10 illuminates the left region 5R of the imaging visual field 5, respectively. That is, the side illuminating units 6B (R) and 6B (L) are arranged in the upper unit 10 and the lower unit 9 respectively corresponding to the right region 5R and the left region 5L which are two illumination regions in the imaging visual field 5. Are provided.
[0019]
Next, a control system of the observation apparatus for a spherical body will be described with reference to FIG. The control unit 11 of the sphere observation device 1 includes an illumination control unit 12 and an image recognition unit 20. The image recognition unit 20 is connected to the camera 4, obtains an image of the solder bump 3 captured by the camera 4, detects the annular bright portion 14 from the image, and recognizes the solder bump 3. The illumination control unit 12 turns on / off the front-back illumination units 6A (F) and 6A (R) and the side illumination units 6B (R) and 6B (L) and adjusts the light amount. Here, as for the side illumination units 6B (R) and 6B (L), the lower unit 9 and the upper unit 10 are individually controlled, and the lower unit 9 and the upper unit 10 emit illumination light having different light intensities. You can do it.
[0020]
As a result, as shown in FIG. 5, the light intensity of the lower unit 9 and the upper unit 10 having the right area 5R and the left area 5L as illumination areas respectively is adjusted to the distance from the light source to the illumination area (here, the lower unit 9). , The average distance from the upper unit 10 (D1, D2). Therefore, unlike the illumination method of irradiating the illumination light to the solder ball 3 to be illuminated from an oblique direction as shown in the present embodiment, a difference in distance from the light source depending on the position of the solder ball 3 can be avoided. Even in the case where there is no illuminance, the illuminance on the surface of each solder ball 3 can be made as uniform as possible.
[0021]
Thereby, when the solder ball 3 having a metallic glossy surface is to be imaged, a high-quality image can be obtained with uniform illumination conditions, and a highly accurate observation result can be obtained. In the above-described embodiment, an example in which the light intensity of the light emitting elements 7 of the side lighting units 6B (R) and 6B (L) is set in two stages using the lower unit 9 and the upper unit 10 as control units. Although shown, the light emitting elements 7 may be individually controlled to set the light intensity in multiple stages. According to this method, the illuminance on the surface of each solder ball 3 can be made more uniform.
[0022]
Furthermore, the size of the illumination unit 6 can be reduced as compared with a conventional ring illumination device used for imaging of a spherical body such as a solder ball, so that the device can be made compact and simplified. Since the light source can be arranged at a position close to the object to be illuminated, the required amount of light can be reduced and the equipment cost can be reduced.
[0023]
【The invention's effect】
According to the present invention, a pair of front-back illumination units disposed along the imaging field with the illumination unit illuminating the elongated imaging field of view of the line camera sandwiching the imaging field from the front-back direction in the transport direction, By providing a pair of side illuminating units disposed on the side of the imaging visual field with the imaging visual field sandwiched from the left and right directions, a compact illuminating unit can be obtained while uniform illumination conditions are provided to ensure good observation results. As a result, the equipment can be simplified and the cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a perspective view of an apparatus for observing a spherical body according to an embodiment of the present invention; FIG. 2 is a plan view of an illumination unit of the apparatus for observing a spherical body according to an embodiment of the present invention; FIG. 2B is a cross-sectional view in the second direction of the illumination unit of the spherical body observation device according to the embodiment of the present invention. FIG. 2B is a first direction cross-sectional view of the illumination unit of the spherical body observation device according to the embodiment of the present invention. FIG. 4 is a block diagram illustrating a configuration of a control system of an illumination unit in the spherical object observation apparatus according to one embodiment of the present invention. FIG. 6 is an explanatory diagram of a method of illuminating a body. FIG. 6 is an explanatory diagram of a method of illuminating a spherical body by an illumination unit of the apparatus for observing a spherical body according to one embodiment of the present invention.
2 board 3 solder ball (ball)
4 Camera 6 Illumination unit 6A (F), 6A (R) Front-rear illumination unit 6B (R), 6B (L) Side illumination unit 7 Light emitting element 8 Illumination unit 9 Lower unit 10 Upper unit 12 Illumination controller

Claims (3)

What is claimed is: 1. An observing apparatus for observing a plurality of spherical bodies arranged in a plane on a workpiece, wherein the oblong apparatus is relatively movable in a first direction with respect to the workpiece and has a second direction orthogonal to the first direction as a longitudinal direction. A camera having an imaging field of view, and an illuminating unit for illuminating the imaging field of view from the surroundings, wherein the illuminating unit is disposed along the imaging field with the imaging field sandwiched from the front-back direction in the first direction. A spherical body comprising: a pair of front-rear illuminating units; and a pair of side illuminating units disposed laterally of the imaging visual field with the imaging visual field sandwiched from left and right in the first direction. Observation device. The apparatus for observing a spherical body according to claim 1, wherein the side illuminating unit includes a plurality of light emitting elements corresponding to an illuminating region in the imaging field of view. The apparatus according to claim 2, wherein the light intensity of the light emitting element is set based on the distance between the illumination area and the light emitting element.

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