JP2000161916A - Inspection device for semiconductor packages - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure ball coplanarity accurately and at high speed. SOLUTION: This device is equipped with a line sensor 1 for two-dimensional measurement which picks up the an over all image of a ball terminal, a line sensor 2 for three-dimensional measurement which picks up image of all the ball terminals obliquely to the terminal formation surface of the package P, and a driving mechanism 11 which moves these line sensors 1 and 2 and package P relatively. The center positions of the respective ball terminals are found from the image of all the ball terminals picked up by the line sensor 1, and the vertexes of the ball terminals are recognized from the image of all the ball terminals picked up by the line sensor 2, then the two-dimensional position degrees of the respective ball terminals are recognized from the center position data and correlated with vertex date to convert the vertex data into one piece of lane data, and a virtual plane along the vertexes of the ball terminal group is obtained from the data after the conversion to find the ball coplanarity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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]

2. Description of the Related Art Conventionally, as a device for inspecting a ball terminal of a BGA / CSP package, there has been a laser displacement measuring device, and a device using image processing has been proposed.

A laser displacement measuring apparatus accommodates a semiconductor package in a tray in an inverted state, and scans a ball terminal on the back surface of the package with a laser beam, thereby obtaining a semiconductor package.
This device measures the presence or absence of ball terminals, ball pitch, ball diameter, ball shape, and ball position (position shift). In addition to such ball measurement, a three-dimensional laser displacement measuring device for measuring the flatness (ball coplanarity) of a ball terminal array has been put to practical use.

[0004] As an inspection apparatus using image processing, there is an inspection apparatus which measures the height of a ball by calculating the amount of movement of a small glossy circle on the top surface of a ball from a two-dimensional image and a three-dimensional image.

[0005]

According to the laser displacement measuring device, the apex of the ball terminal must be accurately irradiated with the laser light, and the laser light is applied to all the ball terminals in the package. Since it is necessary to scan, much time is required for measurement. In addition, since the apex of the ball terminal is irradiated with laser light and the reflected laser light is measured by a sensor optical system, there is no problem if the surface condition of the ball terminal is good, but the entire ball terminal is clouded. If there is no gloss at the apex, or if there is a flaw on the surface of the apex of the ball terminal, an accurate measurement result cannot be obtained.

Further, the scanning of the laser beam is performed along the column direction or the row direction of the ball terminal array. However, the scanning position of the laser beam is not always adjusted to the ball position due to an error in the positioning of the package storage tray with respect to the measurement position. There is also a problem that the ball coplanarity measurement is not always reliable because it does not always coincide with the vertex of the terminal.

On the other hand, as a conventional idea using image processing, as shown in FIG. 8, a small glossy circle is formed on the top surface of the ball by illumination, and the position of the small glossy circle in the ball image by the two-dimensional sensor is used. The height is determined by the difference between (A) and the position (B) of a small glossy circle formed in a three-dimensional image taken obliquely. In this method, the ball top surface may actually occur. If there is clouding due to oxidation, etc., if the top surface is also chipped or scratched and a small circle could not be made, or if the sphericity of the ball has been impaired, a large error will occur. There is a problem that measurement cannot be performed.

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]

According to the present invention, there is provided an inspection apparatus comprising:
An apparatus for inspecting ball terminals two-dimensionally arranged in a semiconductor package such as a GA / CSP package, wherein the ball terminals are formed in a direction orthogonal to a ball terminal forming surface of the semiconductor package.
A two-dimensional measurement line sensor that captures an entire image of a ball terminal, and is arranged in parallel with the two-dimensional measurement line sensor, and captures an overall image of the ball terminal from an oblique direction with respect to the ball terminal formation surface of the semiconductor package. A line sensor for three-dimensional measurement, a drive mechanism for relatively moving the line sensor and the semiconductor package in one direction of a ball terminal array, and an arithmetic processing unit are provided. Then, the arithmetic processing means obtains the center position of each ball terminal from the whole image of the ball terminal imaged by the two-dimensional measurement line sensor, and calculates the whole image of the ball terminal imaged by the three-dimensional measurement line sensor as a curve. By recognizing the apex of each ball terminal by performing an interpolation operation, and then recognizing the two-dimensional position of each ball terminal including the inclination of the package from the center position data of the ball terminal, and correlating with the vertex data Vertex data is converted into one plane data, a virtual plane along the vertex of the ball terminal group is obtained from the converted data, and the flatness of the ball terminal array is obtained using the virtual plane. Characterized by

According to the inspection apparatus of the present invention, a plane image and an oblique image of a ball terminal are captured, and the ball coplanarity is obtained from the two image data. The inspection speed can be increased as compared with the laser displacement measuring device.

Further, since the package is moved relative to the line sensor and all ball terminals in the package are imaged, the line sensor (three-dimensional measurement ) Does not cause distortion (shrinkage) in the obtained image in the tilt direction (imaging direction) of the line sensor. This eliminates the need for data correction (soft correction) of an oblique image picked up by the three-dimensional measurement line sensor or hardware correction using a special lens system such as a telecentric lens.

In the three-dimensional measurement, the entire contour of the ball terminal is imaged and the vertex of the ball terminal is obtained from the image, as compared with the conventional method of measuring by moving the position of the small gloss circle. Even when the surface of the apex of the ball terminal is poor, such as when the entire ball terminal is fogged and there is no gloss at the apex, or when the apex surface is scratched,
Even if the sphericity is slightly poor, the apex of the ball terminal can be accurately recognized.

[0013]

Embodiments of the present invention will be described below with reference to 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 the configuration of the signal processing system of the embodiment.

First, the inspection apparatus of the present embodiment converts the loader tray T1 handled by a stacking stocker (not shown) and positioned on the moving table 11a into an X.
A first moving mechanism 11 which is conveyed along the axial direction and passes through the two-dimensional / three-dimensional measuring position S1 and an unloader tray T2 positioned on the moving table 12a by the front / back inverting mechanism 13 are moved along the X-axis direction. And transport (1st
And a second moving mechanism 12 for passing through the visual inspection position S2. A predetermined number of packages P are stored in the loader tray T1 in a state where the surface on which the ball terminals B are formed faces upward.

The reversing mechanism 13 covers the loader tray T1 that has passed the two-dimensional / three-dimensional measurement position S1 from above with a waiting empty tray (unloader tray T2).
By inverting the loader tray T1 in the set state and the empty tray upside down, the package P accommodated in the loader tray T1 is transferred to the empty tray in an upside down posture, and then the upper tray (loader Tray T1
) Is removed, and the lower tray (unloader tray T2) is positioned on the moving table 12a of the second moving mechanism 12.

The above-described first moving mechanism 11, second moving mechanism 12, and front / back reversing mechanism 13 are each driven and controlled by a control signal from the arithmetic processing unit 20 in an operation described later.

At the two-dimensional / three-dimensional measurement position S1,
A two-dimensional measurement line sensor (CCD camera) 1 that captures an entire image of the ball terminal B from a direction (directly above) orthogonal to the ball terminal formation surface of the package P that moves in the X-axis direction by the first moving mechanism 11. Are arranged in parallel with the two-dimensional measurement line sensor 1 and obliquely to the ball terminal forming surface of the package P (for example, at an elevation angle of 30 °).
A three-dimensional measurement line sensor (CCD camera) 2 that captures an entire image of the ball terminal B is arranged.

The two-dimensional measurement line sensor 1 and the three-dimensional measurement line sensor 2 are arranged such that the pixel array is along a direction orthogonal to the moving direction of the package P, that is, along the Y-axis direction. In addition, 2D / 3D measurement position S
1, two illumination light sources 4 are arranged below the two-dimensional measurement line sensor 1 so as to face each other with the optical axis of the line sensor 1 interposed therebetween.

At the appearance inspection position S 2, an appearance inspection line sensor (CCD camera) 3 (a plurality of CCD cameras may be provided) for capturing a planar image of the surface of the package P moved in the X-axis direction by the second moving mechanism 12 and a plurality thereof. An illumination light source 5 is provided. Note that the visual inspection line sensor 3 is also arranged such that the pixel array is along the direction (Y-axis direction) orthogonal to the moving direction of the package P, as before.

Each output of the line sensor 3 for visual inspection arranged at the visual inspection position S2 and the line sensor 1 for two-dimensional measurement and the line sensor 2 for three-dimensional measurement arranged at the two-dimensional / three-dimensional measuring position S1. As shown in FIG. 2, the signals are sequentially guided to the image processing devices 21, 22, and 23, and are subjected to predetermined signal processing (eg, multi-value processing).
It is adopted in the arithmetic processing unit 20.

The above three line sensors 1, 2, 2
3 and its illumination light sources 4 and 5, respectively,
The drive is controlled by the two-dimensional measurement line sensor 1
The three-dimensional measurement line sensor 2 and the illumination light source 4 are turned on while the loader tray T1 passes the two-dimensional / three-dimensional measurement position S1, and the visual inspection line sensor 3 and its illumination light source 5 are , Unloader tray T
ON while 2 passes the visual inspection position S2
Becomes

The arithmetic processing unit 20 is based on plane image data (see FIG. 3) from the two-dimensional measurement line sensor 1 which is collected when the package P passes through the two-dimensional / three-dimensional measurement position S1. The presence / absence of a ball terminal, the ball diameter and the ball shape are determined, the center position of each ball terminal B on the plane image data is determined, and the ball pitch and the ball position are determined from the center position data.

The arithmetic processing unit 20 processes the oblique image data (see FIG. 4) from the three-dimensional measurement line sensor 2 and recognizes the vertices of each ball terminal B on the plane image data. The ball coplanarity is obtained using the vertex data and the previously obtained center position data.

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 data and the angle data (30 °) of the three-dimensional measurement are fed back to the vertex data of the ball terminal to obtain a correlation.
An operation process is performed such that the data is converted into two plane data, a virtual plane along the vertex group of the ball terminal is obtained from the converted data by the least square method, and the ball coplanarity is obtained using the virtual plane.

Further, the arithmetic processing unit 20 determines the presence / absence of a mark, chipping, missing characters, and package void based on the image data from the visual inspection line sensor 3 which is collected when the package P has passed the visual inspection position S2. Is determined.

In addition to the above-mentioned processing, the arithmetic processing unit 20 also outputs data on ball pitch, ball diameter, ball position and ball coplanarity, and data on marks and package voids to a video monitor 24 such as a CRT. , Output to an external device such as an FFD (floppy disk drive) 25 and a printer 26.

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 upward, and the loader tray T1 is stored in a stacking stocker (not shown).

When the inspection is started, one loader tray T1 is taken out of 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,
The loader tray T1 is in the 2D / 3D measurement position S1
, And passes through the measurement position S1, the two-dimensional measurement line sensor 1 and the three-dimensional line sensor 2 capture a plane image and an oblique image of the ball terminal B of the package P in the loader tray T1. Then, each of the image data is taken into the arithmetic processing unit 20.

Next, when the loader tray T1 reaches the front / back inversion position, the front / back inversion mechanism 13 is driven, and the package P on which the two-dimensional / three-dimensional measurement has been completed is loaded into the loader tray T.
1 is transferred to the unloader tray T2, and the unloader tray T2, that is, the unloader tray T2 in which the package P is stored with its front side facing up, is positioned on the moving table 12a of the second moving mechanism 12. In addition,
The loader tray T1 emptied by the transfer of the package P is stored in the collection stocker.

When the above-described 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. . Further, at the time when the front / back reversal operation is completed, the second moving mechanism 12 is driven, and the unloader tray T2 moves toward the visual inspection position S2, and when passing through the inspection position S2, the line sensor for visual inspection is used. 3 captures a planar image of the surface of the package P, and the image data is processed by the arithmetic processing unit 20.
It is taken in. During such an appearance inspection process, the first moving mechanism 11 is driven, and the two-dimensional and three-dimensional measurement processes of the package P in the next loader tray T1 are executed in parallel. .

With the above, the measurement for one tray is completed. Based on the image data taken at the two-dimensional / three-dimensional measurement position S1, the arithmetic processing unit 20 determines whether or not there is a ball terminal.
Ball pitch, ball diameter, ball shape, ball position,
In addition, the ball coplanarity is obtained, and it is determined whether or not each data is within an allowable range, and the presence or absence of a mark defect / package void is determined from the image data collected at the visual inspection position S2. From the package P is determined. If there is a package defect, a refill position (not shown)
, A refilling process is performed between the defective package and a previously prepared non-defective package.

According to the above-described embodiment, the ball measurement at the two-dimensional / three-dimensional position S1 and the mark / package void inspection at the visual inspection position S2 can be performed with the same tact. In performing the package appearance inspection (ball measurement + mark / package void inspection), the inspection tact can be reduced.

Here, in the inspection apparatus of the present invention, since the ball coplanarity is obtained by the above-described arithmetic processing, accurate ball coplanarity measurement can be always performed. The reason will be described in detail below with reference to FIG. 1 and FIGS.

First, the ball terminals BB of the package P are formed with high precision, and the ball terminals BB arranged in the column or row direction (Y direction in FIG. 1) of the two-dimensional array are located on a straight line. In this case, there is no difference in the distance between each ball terminal B and the line sensor 2 for three-dimensional measurement in the imaging direction of the line sensor 2 for three-dimensional measurement. There is no problem if the ball coplanarity is obtained only from the vertex data obtained from the data.

However, as shown in FIGS. 5 and 6, when the ball terminals B are not arranged in a straight line, the distance between the ball terminals B in the imaging direction of the three-dimensional measurement line sensor 2 is determined. In fact, although the vertex heights of all the ball terminals B are the same (FIG. 5), as shown in FIG. Are not aligned on a straight line, and the vertex heights are different. That is, when the ball terminal B is imaged in an oblique direction, the ball terminals B,.
Position accuracy has a great influence on the measurement accuracy.

In the inspection apparatus of the present invention, in consideration of such a point, the center position of each ball terminal is obtained based on the plane image data from the two-dimensional measurement line sensor 1, and the center position data is obtained by 3 By feeding back to the oblique image (three-dimensional image) of the ball terminal obtained by the line sensor 2 for dimension measurement, the two-dimensional inclination of the package P and the influence of the positional accuracy of each ball terminal are corrected. According to the inspection apparatus of the present invention, of the illumination light applied to the ball terminal, the whole contour (oblique image) of the ball terminal is imaged instead of measuring the vertex of the ball terminal from the specularly reflected light at the vertex of the ball terminal. However, since the vertex of the ball terminal is recognized by the image processing, even if the surface state near the vertex of the ball terminal is bad and normal reflected light cannot be obtained, It is possible to always accurately detect the apex of the ball terminals. As a result, accurate ball coplanarity can always be obtained.

[0038]

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. In addition, since the entire image of the ball terminal is captured, the vertex position of the ball terminal is recognized from the image data, and the ball coplanarity is obtained, the ball terminal is fogged or the ball top has a scratch or the like. However, it is practical because accurate measurement can always be performed irrespective 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 illustrating 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 when obtaining ball coplanarity in the inspection device 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 measuring method in an inspection device using image processing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 2D measurement line sensor 2 3D measurement line sensor 3 Visual inspection line sensor 4,5 Illumination light source 11 1st moving mechanism 12 2nd moving mechanism 13 Front / back inversion mechanism 20 Arithmetic processing unit 21,22 23 Image processing device P Package T1 Loader tray T2 Unloader tray S1 2D / 3D measurement position S2 Visual inspection position

Continuation of the front page F term (reference) 2F065 AA00 AA03 AA04 AA16 AA17 AA21 AA24 AA26 AA31 AA47 AA49 AA51 BB07 BB15 BB18 CC26 DD06 FF04 FF42 GG14 GG16 HH12 HH14 JJ03 JJ05 JJ08 Q03 GG08 NN09 SS13 TT01 TT02 TT07 TT08 2G051 AA61 AA62 AB20 BA01 CA03 CA04 CA07 CB01 EA11 EC06 FA10

Claims (1)

[Claims] 1. An apparatus for inspecting ball terminals arranged in a semiconductor package such as a BGA / CSP package, wherein a two-dimensional image of an entire image of the ball terminals is taken from a direction orthogonal to a ball terminal forming surface of the semiconductor package. A line sensor for measurement, a line sensor for three-dimensional measurement which is arranged in parallel with the line sensor for two-dimensional measurement, and captures an entire image of the ball terminal from an oblique direction with respect to the ball terminal formation surface of the semiconductor package; A driving mechanism for relatively moving the sensor and the semiconductor package in one direction of the ball terminal array; and an arithmetic processing means, wherein the arithmetic processing means is an entire image of the ball terminal imaged by the two-dimensional measurement line sensor. The center position of each ball terminal is calculated from the overall image of the ball terminal captured by the three-dimensional measurement line sensor. Recognizing the vertices of Le terminal, then 2 from the center position data of the ball pin of the ball pin
The vertex data is converted into one plane data by recognizing the dimensional position and correlating with the vertex data, and a virtual plane along the vertex of the ball terminal group is obtained from the converted data. A semiconductor package inspection apparatus characterized in that the flatness of a ball terminal array is obtained by using the method.