JP4191295B2 - Semiconductor package inspection equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for inspecting ball terminals (solder bumps) arranged in a semiconductor package such as a BGA / CSP package.
[0002]
[Prior art]
Conventionally, as a device for inspecting a ball terminal of a BGA / CSP package, there is a laser displacement measuring device, and a device using image processing has been proposed.
[0003]
The laser displacement measuring device accommodates the semiconductor package in an inverted state on a tray and scans the ball terminal on the back surface of the package with laser light to detect the presence / absence of the ball terminal, the ball pitch, the ball diameter, the ball shape, and the ball position. It is a device that measures the degree (positional deviation). In addition to such ball measurement, a three-dimensional laser displacement measuring device that measures the flatness (ball coplanarity) of the ball terminal array has been put into practical use.
[0004]
Some inspection apparatuses using image processing attempt to measure the ball height by obtaining the amount of movement of the small gloss circle on the top of the ball from the two-dimensional image and the three-dimensional image.
[0005]
[Problems to be solved by the invention]
By the way, according to the laser displacement measuring apparatus, it is necessary to accurately irradiate the apex of the ball terminal with the laser beam and to scan all the ball terminals in the package. It takes a lot of time. In addition, since the laser light is irradiated to the apex of the ball terminal and the reflected laser light is measured by the sensor optical system, there is no problem if the surface condition of the ball terminal is good, but the entire ball terminal is cloudy. If the vertex of the ball terminal is not glossy or the surface of the ball terminal is scratched, an accurate measurement result cannot be obtained.
[0006]
Furthermore, the laser beam scan is performed along the column direction or the row direction of the ball terminal array. However, due to a positioning error of the package storage tray with respect to the measurement position, the laser beam scan position is not necessarily the apex of the ball terminal. There is also a problem that the reliability of ball coplanarity measurement is not necessarily met.
[0007]
On the other hand, as a conventional idea using image processing, as illustrated in FIG. 8, a glossy small circle is formed on the top surface of the ball by illumination, and the position of the glossy small circle in the ball image by the two-dimensional sensor (A) And the position of the glossy small circle (B) formed in the three-dimensional image taken obliquely, the height is obtained, but in this method, the top surface of the ball can actually occur, oxidation, etc. If there is cloudiness due to the above, or if the top surface is chipped and scratched and a small circle cannot be made, or if the sphericity of the ball is impaired, measurement can be performed with a large error. There is a problem of disappearing.
[0008]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a semiconductor package inspection apparatus capable of performing ball coplanarity measurement accurately and at high speed.
[0009]
[Means for Solving the Problems]
The inspection apparatus of the present invention is an apparatus for inspecting ball terminals arranged in a semiconductor package such as a BGA / CSP package, and picks up an entire image of the ball terminals from a direction orthogonal to the ball terminal formation surface of the semiconductor package. A line sensor for two-dimensional measurement, and a line sensor for three-dimensional measurement that is arranged in parallel to the line sensor for two-dimensional measurement and that captures an outline image of each ball terminal from a direction oblique to the ball terminal formation surface of the semiconductor package; The line sensor and the semiconductor package are provided with a drive mechanism that relatively moves in one direction of the ball terminal array, and an arithmetic processing unit. The arithmetic processing means, from the entire image of a ball pin which is captured in the 2-dimensional measurement line sensor, obtains the center position of each ball terminal, the three-dimensional measuring line sensor on the basis of the center position data captured The position of each ball terminal in the direction is recognized, and the contour vertex of each ball terminal is recognized by image processing of the contour image of each ball terminal imaged by the three-dimensional measurement line sensor, and the contour vertex of each ball terminal The data is corrected using the position data of each ball terminal in the imaging direction of the three-dimensional measurement line sensor, a virtual plane along the contour vertex of the ball terminal group is obtained from the corrected data, and the virtual plane is used. Characterized by being configured to determine the flatness of the ball terminal array.
[0010]
According to the inspection apparatus of the present invention, a plane image and an oblique image of the ball terminal are taken, and the ball coplanarity is obtained from the two image data. Therefore, the laser displacement measurement is performed by scanning the apex of the ball terminal with a laser beam. Compared with the apparatus, the inspection speed can be increased.
[0011]
Moreover, since the package is moved relative to the line sensor and all ball terminals in the package are imaged, the line sensor (for three-dimensional measurement) is tilted with respect to the ball terminal forming surface of the package. Even if they are arranged, the distortion (shrinkage) in the tilt direction (imaging direction) of the line sensor does not occur in the obtained image. This eliminates the need for data correction (software correction) of an oblique image captured by the three-dimensional measurement line sensor, or hardware correction using a special lens system such as a telecentric lens.
[0012]
Also, in the three-dimensional measurement, compared to the conventional method of measuring by moving the position of the glossy small circle, the entire contour of the ball terminal is imaged and the vertex of the ball terminal is obtained from the image, so the entire ball terminal If the surface condition of the apex part of the ball terminal is poor, such as when the surface is cloudy and the apex is not glossy, or the apex surface has scratches, etc. The vertex of the terminal can be recognized accurately.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0014]
FIG. 1 is a perspective view showing a schematic configuration of an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of the signal processing system according to the embodiment.
[0015]
First, the inspection apparatus according to the present embodiment handles a loader tray T1 which is handled from a stacking stocker (not shown) and positioned on the moving table 11a, along the X-axis direction, and is two-dimensional / three-dimensional. The first moving mechanism 11 for passing the measurement position S1 and the unloader tray T2 positioned on the moving table 12a by the front / back reversing mechanism 13 are transported along the X-axis direction (opposite to the first moving mechanism 11). And a second moving mechanism 12 that allows the appearance inspection position S2 to pass therethrough. A predetermined number of packages P are stored in the loader tray T1 with the ball terminal B formation surface facing upward.
[0016]
The front / back reversing mechanism 13 covers the loader tray T1 that has passed through the two-dimensional / three-dimensional measurement position S1 with the empty tray (unloader tray T2) that is waiting from above, and the upper and lower sides of the loader tray T1 and the empty tray in the set state. , The package P accommodated in the loader tray T1 is transferred to the empty tray in a posture in which the front and back are reversed, and then the upper tray (loader tray T1) is removed, and the lower tray (unloader tray) The operation of positioning T2) on the moving table 12a of the second moving mechanism 12 is performed.
[0017]
The first moving mechanism 11, the second moving mechanism 12, and the front / back reversing mechanism 13 described above are driven and controlled by operations described later by control signals from the arithmetic processing unit 20.
[0018]
At the two-dimensional / three-dimensional measurement position S1, an entire image of the ball terminal B is picked up from the direction (directly above) the ball terminal forming surface of the package P that is moved in the X-axis direction by the first moving mechanism 11. The two-dimensional measurement line sensor (CCD camera) 1 and the two-dimensional measurement line sensor 1 are arranged in parallel to the ball terminal formation surface of the package P from an oblique direction (for example, an elevation angle of 30 °). A three-dimensional measurement line sensor (CCD camera) 2 for capturing the entire image is arranged.
[0019]
The two-dimensional measurement line sensor 1 and the three-dimensional measurement line sensor 2 are arranged so that the pixel arrangement is along the direction orthogonal to the moving direction of the package P, that is, the Y-axis direction. At the two-dimensional / three-dimensional measurement position S1, two illumination light sources 4 facing each other across the optical axis of the line sensor 1 are arranged below the two-dimensional measurement line sensor 1.
[0020]
At the appearance inspection position S2, an appearance inspection line sensor (CCD camera) 3 (which may be a plurality of cameras) 3 for picking up a planar image of the surface of the package P moved in the X-axis direction by the second moving mechanism 12 and its illumination light source 5 is arranged. In addition, the appearance inspection line sensor 3 is also arranged so that the pixel arrangement is along the direction (Y-axis direction) orthogonal to the moving direction of the package P, as before.
[0021]
The output signals of the visual inspection line sensor 3 arranged at the visual inspection position S2 and the two-dimensional measurement line sensor 1 and the three-dimensional measurement line sensor 2 arranged at the two-dimensional / three-dimensional measurement position S1 are: As shown in FIG. 2, the images are sequentially guided to the image processing devices 21, 22, and 23, and after being subjected to predetermined signal processing (multi-value processing or the like), they are taken into the arithmetic processing device 20.
[0022]
The three line sensors 1, 2, 3 and the illumination light sources 4, 5 are controlled by the arithmetic processing unit 20, and the two-dimensional measurement line sensor 1 and the three-dimensional measurement line sensor 2 The illumination light source 4 is turned on while the loader tray T1 passes through the two-dimensional / three-dimensional measurement position S1, and the appearance inspection line sensor 3 and its illumination light source 5 are connected to the unloader tray T2 at the appearance inspection position S2. ON while passing.
[0023]
The arithmetic processing unit 20 detects the ball terminal based on the plane image data (see FIG. 3) from the two-dimensional measurement line sensor 1 collected when the package P passes the two-dimensional / three-dimensional measurement position S1. The presence / absence, the ball diameter and the ball shape are obtained, the center position of each ball terminal B on the plane image data is obtained, and the ball pitch and the ball position degree are obtained from the center position data.
[0024]
The arithmetic processing unit 20 processes the oblique image data (see FIG. 4) from the three-dimensional measurement line sensor 2, recognizes the vertex of each ball terminal B on the planar image data, and obtains the vertex data. And the center position data obtained previously are used to obtain the ball coplanarity.
[0025]
Specifically, an inclination (positioning error of the loader tray T1 and the package P) with respect to the X axis in the arrangement direction (row direction) of the ball terminals at the time of imaging is obtained from the center position data of all the ball terminals. The angle data (30 °) of the dimension measurement is fed back to the ball terminal vertex data to obtain a correlation, and the vertex data is converted into one plane data. From the converted data, the least square method is used to calculate the ball terminal data. An arithmetic process such as obtaining a virtual plane along the vertex group and obtaining the ball coplanarity using the virtual plane is performed.
[0026]
Further, the arithmetic processing unit 20 uses the image data from the visual inspection line sensor 3 collected when the package P passes the visual inspection position S2, and the presence / absence of marks, missing characters, missing characters, package voids, etc. Determine.
[0027]
In addition to the above processing, the arithmetic processing unit 20 receives data on ball pitch, ball diameter, ball position and ball coplanarity, and data on mark / package voids from a video monitor device 24 such as CRT, FFD ( A process of outputting to an external device such as a floppy disk drive 25 and a printer 26 is also performed.
[0028]
Next, the inspection operation of this embodiment will be described.
First, the package P is set on the loader tray T1 with the ball terminal forming surface facing up, and the loader tray T1 is stored in a stacking stocker (not shown).
[0029]
When the inspection is started, one loader tray T1 is taken out from the stacking stocker and positioned on the moving table 11a of the first moving mechanism 11. When this operation is completed, the first moving mechanism 11 is driven, and the loader tray T1 moves toward the two-dimensional / three-dimensional measurement position S1 and passes through the measurement position S1. A plane image and an oblique image of the ball terminal B of the package P in the loader tray T1 are picked up by the line sensor 1 and the three-dimensional line sensor 2, and each image data is taken into the arithmetic processing unit 20.
[0030]
Next, when the loader tray T1 reaches the front / back reversal position, the front / back reversing mechanism 13 is driven, and the package P for which the two-dimensional / three-dimensional measurement is completed is transferred from the loader tray T1 to the unloader tray T2, The unloader tray T2, that is, the unloader tray T2 in which the package P is accommodated with the front side facing up, is positioned on the moving table 12a of the second moving mechanism 12. Note that the loader tray T1 that has become empty by the transfer of the package P is stored in the collection stocker.
[0031]
When the above front / back reversal operation is completed, the first moving mechanism 11 is driven, the moving table 11a returns to the initial position, and the next loader tray T1 is positioned on the moving table 11a. When the front / back reversing operation is completed, the second moving mechanism 12 is driven, and the unloader tray T2 moves toward the appearance inspection position S2 and passes through the inspection position S2. 3, a planar image of the surface of the package P is picked up, and the image data is taken into the arithmetic processing unit 20. During the appearance inspection process, the first moving mechanism 11 is driven and the next two-dimensional / three-dimensional measurement process of the package P in the loader tray T1 is executed in parallel. .
[0032]
With the above, the measurement for one tray is completed, and based on the image data collected at the two-dimensional / three-dimensional measurement position S1, the arithmetic processing unit 20 determines whether or not there is a ball terminal, the ball pitch, the ball diameter, and the ball shape. , Determine the ball position and ball coplanarity, determine whether each data is within the allowable range, and determine the presence or absence of mark defects / package voids from the image data collected at the appearance inspection position S2. Then, the quality of the package P is determined from these determination results. If there is a package defect, a refill process between the defective package and the good package prepared in advance is executed at a refill position (not shown).
[0033]
According to the above embodiment, since the ball measurement at the 2D / 3D position S1 and the mark / package void inspection at the appearance inspection position S2 can be performed with the same tact, the appearance of the package such as BGA / CSP is obtained. In performing the inspection (ball measurement + mark / package void inspection), the inspection tact can be shortened.
[0034]
Here, in the inspection apparatus of the present invention, since the ball coplanarity is obtained by the arithmetic processing as described above, accurate ball coplanarity measurement can always be performed. The reason will be described in detail below with reference to FIG. 1 and FIGS.
[0035]
First, the ball terminals B... B of the package P are formed with high accuracy, and the ball terminals B... B arranged in the two-dimensional array column or row direction (Y direction in FIG. 1) are positioned on a straight line. Since there is no difference in the distance between each ball terminal B and the three-dimensional measurement line sensor 2 in the imaging direction of the three-dimensional measurement line sensor 2, it is obtained from the image data of the three-dimensional measurement line sensor 2. There is no problem even if the ball coplanarity is obtained only by the vertex data to be obtained.
[0036]
However, as shown in FIGS. 5 and 6, if the ball terminals B... B arranged in a line are not on a straight line, there is a difference in the distance between the ball terminals B in the imaging direction of the three-dimensional measurement line sensor 2. Therefore, in fact, although the vertex heights of all the ball terminals B... B are the same (FIG. 5), on the image data, as shown in FIG. Will not line up on a straight line, and the apex height will be different. That is, when the ball terminal B is imaged from an oblique direction, the positional accuracy of the ball terminals B ·· B in the imaging direction greatly affects the measurement accuracy.
[0037]
In the inspection apparatus of the present invention, in consideration of such points, the center position of each ball terminal is obtained based on the plane image data from the line sensor 1 for two-dimensional measurement, and the center position data is used for three-dimensional measurement. By feeding back to the oblique image (three-dimensional image) of the ball terminal obtained by the line sensor 2, the influence of the two-dimensional inclination of the package P and the positional accuracy of each ball terminal is corrected, and the present invention In the inspection device of, the entire contour (diagonal image) of the ball terminal is captured instead of the method of measuring the vertex of the ball terminal from the specularly reflected light at the vertex of the ball terminal of the illumination light irradiated to the ball terminal. Since the top of the ball terminal is recognized by the processing, the ball terminal is not affected by the surface condition near the top of the ball terminal, even if normal reflected light is not obtained. It is possible to always accurately detect the vertex. As a result, an accurate ball coplanarity can always be obtained.
[0038]
【The invention's effect】
As described above, according to the inspection apparatus of the present invention, the ball coplanarity of a ball terminal such as a BGA / CSP package can be measured at high speed and with high accuracy. Moreover, since the entire ball terminal image is taken and the apex position of the ball terminal is recognized from the image data to determine the ball coplanarity, the ball terminal is cloudy or the ball top is damaged. Even so, it is practical because accurate measurement can always be performed regardless of this.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a schematic configuration of an embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of a signal processing system according to the embodiment of the present invention.
FIG. 3 is a diagram illustrating an example of an image captured by a two-dimensional measurement line sensor according to the embodiment of the present invention.
FIG. 4 is a diagram illustrating an example of an image captured by a three-dimensional measurement line sensor according to the embodiment of the present invention.
FIG. 5 is an explanatory diagram of a calculation method for obtaining ball coplanarity in the inspection apparatus of the present invention.
FIG. 6 is an explanatory diagram of a ball coplanarity calculation method.
FIG. 7 is an explanatory diagram of a ball coplanarity calculation method.
FIG. 8 is an explanatory diagram of a height measurement method in an inspection apparatus using image processing.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Line sensor for two-dimensional measurement 2 Line sensor for three-dimensional measurement 3 Line sensor for appearance inspection 4, 5 Light source for illumination 11 First moving mechanism 12 Second moving mechanism 13 Front / back reversing mechanism 20 Arithmetic processing devices 21, 22 23 Image processing apparatus P Package T1 Loader tray T2 Unloader tray S1 2D / 3D measurement position S2 Visual inspection position

Claims (1)

An apparatus for inspecting ball terminals arranged in a semiconductor package such as a BGA / CSP package,
A two-dimensional measurement line sensor that captures the entire image of the ball terminal from a direction orthogonal to the ball terminal formation surface of the semiconductor package, and the two-dimensional measurement line sensor are arranged in parallel to the ball terminal formation surface of the semiconductor package. On the other hand, a three-dimensional measurement line sensor that captures an outline image of each ball terminal from an oblique direction, a drive mechanism that relatively moves the line sensor and the semiconductor package in one direction of the ball terminal array, an arithmetic processing unit, With
The calculation processing means, in the overall search of the center position of each ball terminal from the image, the imaging direction of the three-dimensional measuring line sensor on the basis of the center position data of the ball pin captured in the 2-dimensional measurement line sensor Recognize the position of each ball terminal, recognize the contour vertex of each ball terminal by image processing of the contour image of each ball terminal imaged by the three-dimensional measurement line sensor, and obtain the contour vertex data of each ball terminal. Correction is performed using position data of each ball terminal in the imaging direction of the three-dimensional measurement line sensor, a virtual plane along the contour apex of the ball terminal group is obtained from the corrected data, and the ball terminal is used using the virtual plane. An inspection apparatus for a semiconductor package, characterized in that the flatness of the array is obtained.

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