JP2887683B2 - IC package inspection apparatus and IC package inspection method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an IC package inspection system.

BACKGROUND OF THE INVENTION Ceramic packages are widely used for shrinking integrated circuits (ICs), and various patterns are formed on the package surface to electrically connect the ICs to external circuits. Printed and plated. This pattern has some defective products, such as a part missing, a part bulging conversely, an entire pattern not being printed, and being not plated. For this reason, this defect must be inspected, but use of a television camera for inspecting the print pattern has been considered in recent years.

The present invention is intended to more accurately and efficiently inspect an IC package using the television camera.

[Means for Solving the Problems] In order to achieve the above object, in the present invention, the number of pattern images of a pattern to be inspected is counted, and the number is compared with the number of pattern images of a pattern to be inspected that has passed. Then, the pass / fail of the pattern to be inspected is determined. Further, the number of pixels of the pattern to-be-inspected is counted in a specific coordinate direction, and the number of pixels is compared with the number of pixels of the pattern-of-inspection pattern image that has passed, thereby determining whether the pattern to be inspected is pass or failure. Things.

[Operation] With this, for example, when the pattern is excessively expanded and short-circuited with an adjacent pattern, the total number of pattern images to be inspected becomes smaller than the number of passed pattern images. If one or more patterns are completely dropped, the total number of pattern images to be inspected is also smaller than the number of passed pattern images. Conversely, if one pattern is broken and separated into a plurality of portions, the total number of pattern images to be inspected becomes larger than the number of passed pattern images. Thus, it can be determined that the product is defective. Also, if the pattern is partially missing or excessively bulging, the number of pixels of the pattern image to be inspected is smaller or partially larger than the number of pixels of the pattern image to be inspected that has passed, It can be determined that the product is defective.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows IC packages 1 and 2. A pattern 10, such as a square, a square frame, or a block, is formed on the IC package 1, and a pattern 10, such as a circle, a ring, or a circular block, is formed on the IC package 2. For these IC packages 1 and 2, the CCD
An imaging inspection by the camera 3 is performed.

FIG. 2 shows a circuit diagram of the IC package inspection device. IC package 1, photographed by CCD camera 3,
The image data of the pattern to be inspected 2 is written into the image memory 4. This image memory 4 is an 8-bit memory,
It has addresses of m rows and n columns. The m rows and n columns are CC
This corresponds to m rows and n columns of the number of pixels captured by the D camera 3.
At each address of the image memory 4, data indicating the brightness of each pixel of the captured inspection pattern is written. This brightness data takes a value of 0 to 255. The image memory 4 may have a configuration other than the 8-bit configuration. A plurality of image memories 4 are provided in advance.

The image data in the image memory 4 is read out by the CPU 6 through the address counter 5, and after image data processing is performed, the density distribution memory 7, the binary image memory 8,
The data is written to the label memory 9. Address counter 5
Has m + n or more counter bits, and outputs data of an m-bit row address and an n-bit column address to the image memory 4.

As shown in FIG. 3, the number of pixels corresponding to each brightness of the image memory 4 is totaled and stored in the density distribution memory 7. As shown in FIG. 4, in the binarized image memory 8, for example, the pattern image 13 portion is “1 (binary logic level high level)” and the pattern image 13 is other than the pattern image 13 based on the storage contents of the density distribution memory 7. Is simplified and the pattern image 13 is stored as "0 (low level of binary logic level)". As shown in FIG. 5, the label memory 9 assigns a number to each independent pattern image 13 and stores each pattern image 13 separately. Access to the density distribution memory 7, the binary image memory, and the label memory 9 is performed through the address counter 5,
This is performed by the CPU 6.

The ROM 11 stores programs for the CPU 6 to perform various types of processing, and the RAM 12 stores various types of processing data for the CPU 6. The RAM 12 stores the number of pattern images 13 to be inspected, the number of pattern images 13 that have passed, the number of pixels of the pattern image 13 to be inspected, and the number of pixels of the pattern image 13 of the master pattern that has passed.

Prior to the inspection processing, threshold data T necessary for obtaining a binarized image obtained by simplifying the pattern image 13 is obtained by the following processing. Therefore, the CPU 6 first creates the density distribution data shown in FIG. It is created as follows. The image data in the image memory 4 is read out for each pixel, and totalization is performed for each brightness of 0 to 225, and density distribution data is created. The density distribution data is divided into a distribution peak of the relatively bright pattern image 13 and a distribution peak of the image portion other than the relatively dark pattern portion. And a small mountain is created between these two mountains. This is the peak of the image portion of the printing failure and the plating failure.

FIG. 6 is a view showing a flowchart of an IC package inspection process.

In this process, the CPU 6 expands the pattern image 13 shown in FIG. 7A with respect to the image data of the pattern 10 stored in the image memory 4 (step 01). This expansion is processing for expanding the pattern image 13 by one column of pixels toward portions other than the pattern portion. If this process is repeated a plurality of times, the pattern image 13 expands by a plurality of rows. As a result, as shown in FIG. 7B, the pinholes (small omissions of the pattern 10) in the pattern image 13 are filled up.

Next, the pattern image 13 shown in FIG. 7 (C) is contracted (step 02). This contraction is a process of contracting the pattern image 13 by one column of pixels toward portions other than the pattern portion. By repeating this process multiple times, the pattern image
13 shrinks by a plurality of columns. As a result, as shown in FIG. 7 (C), the size of the pattern image 13 returns to the original size before the expansion while the pinholes (small omissions of the pattern 10) in the pattern image 13 are filled up. Become.

The expansion and contraction processing is performed, for example, as follows. The image data of each pixel (i, j) is sequentially read out from the image memory expansion 4, and its surroundings (i-1, j-
1), (i, j-1) (i + 1, j-1), (i-1,
j), (i + 1, j), (i-1, j + 1), (i, j
+1) and (i + 1, j + 1) are read together, and in the case of expansion, the image data of the pixel (i, j) is replaced with the image data of (i, j) and the eight surrounding image data. In the case of contraction, the image data of the pixel (i, j) is replaced with the minimum value of the image data of (i, j) and the surrounding eight image data. Image memory. This becomes expanded image data or contracted image data. The expansion and contraction may be performed by another method, or may be performed after conversion into binary image data as described later.

Then, the original image data of FIG. 7 (A) is subtracted for each pixel from the expanded and contracted image data of FIG. 7 (C) to extract a gray image of a defective portion (step 0).
3). Next, the grayscale image of the defective portion is converted into binarized image data using an appropriate threshold value, for example, threshold data T described later, and is labeled and distinguished for each defective portion (step 04). It is determined whether or not the area is equal to or larger than the allowable value allowed as a passable product (step 05).

This labeling is performed, for example, as follows.
Image data of each pixel (i, j) is sequentially read from the image memory 4 in the vertical direction from the upper left to the lower right. It is determined whether or not this image data is equal to or more than an appropriate threshold, for example, threshold data T to be described later, that is, whether or not the image data is the pattern image 13. If the data is equal to or larger than the threshold data T, the label number of an adjacent pixel is checked. This label number has already been written in the label memory 9. The adjacent pixels are (i-1, j-
1), (i-1, j), (i-1, j + 1), (i, j)
-1) or (i-1, j) and (i, j-1).

If a label number, for example, k, has been written to the adjacent pixel, the label number k is written to the address corresponding to the pixel (i, j) in the label memory 9. Thereby, the same label number is written for each pixel of one connected pattern image 13. If the label numbers of adjacent pixels are all “0”, a new label number that has not been used is written. For example, if the label numbers “1” to “3” have been written so far, the label number “4” is newly written. Thereby, as shown in FIG. 5, a different label number is assigned to each of the independent pattern images 13 that are not connected.

If a plurality of different values are written in the label numbers of adjacent pixels, the minimum value of the plurality of label numbers is written. Then, the label number of the pattern image 13 in which the label number other than the minimum value has already been written is rewritten to the label number of the minimum value. Thereby, if it is found that the pattern images 13 to which different label numbers are initially assigned are connected later, they are reassigned to the same label number.

Finally, the label numbers of the label memory 9 allocated as described above are read out, and "1" is sequentially assigned from the smallest one.
Start with a serial number.

This labeling may be performed based on the binarized image data of the binarized image memory 8 instead of the image data of the image memory 4. In this case, it is not necessary to determine whether the data is equal to or larger than the threshold data T.

The calculation of each area of each pattern image 13 after the above-described labeling is performed as follows. Each label number is sequentially read from the label memory 9 and totalized for each label number value. This total value is calculated for each pattern image 13
Represents the area of each.

In the inspection processing of steps 01 to 05, an inspection of a pinhole (a small omission of the pattern 10) in the area of the pattern 10 is performed. In this processing, since the image data is not converted to the binarized image data until the end, there is an advantage that it is not affected by uneven lighting conditions.

The process for obtaining the threshold data T is as follows. First, the maximum value Xmax and the mode Xm of the density distribution data of the pattern image 13 shown in FIG.
Determine ode. Next, the minimum value Xmin of the density distribution data of the pattern image 13 is obtained from the following equation.

Xmin = Xmode−a × (Xmax−Xmode) (a is a constant) Then, between the minimum value Xmin and the maximum value Xmax, the average value X,
The standard deviation c is obtained, and the threshold data T is obtained from the following equation.

T = X−b × c (b is a constant) Next, the CPU 6 reads out the image data of the image memory 4 for each pixel (step 06), and if it is larger than the threshold data T, it is “1”; Is converted to binary image data (step 07) and written into the binary image memory 8 (step 08). Then, as shown in FIG. 8 (B), the above-described expansion processing is performed several times on the binary image data (step 09). Next, the above-described labeling process is performed (step 10), and it is determined whether or not the number of labeling matches the number of labeling of the acceptable product (step 10).
11). The number of labeling of the accepted product is input and stored in advance. The labeling may be performed on the image data in the image memory 4 instead of the binarized image data.

In the inspection processing of steps 06 to 11, the pattern 10 is excessively expanded and short-circuited with the adjacent pattern 10 or the pattern 10
A dropout of one, one pattern 10 is largely missing, and separation into a plurality of parts is determined. That is, if the pattern under test 10 is short-circuited, the number of labeling of the pattern under test 10... If one or more of the patterns 10 are completely dropped, the number of labeling of the pattern to be inspected 10... Is also smaller than the number of labeling of acceptable products. Conversely, if one pattern 10 is broken and separated into a plurality of portions, the number of labeling of the pattern to be inspected 10... In this way, it can be determined that the product is defective.

Note that the expansion process may be omitted, but it is better not to omit it. Even if the pattern 10 is excessively expanded and does not short-circuit with the adjacent pattern 10, or if the pattern is near-short, the pattern is connected to the adjacent pattern 10 and detected as a defective product. this is,
The reason for this near short is that the performance is not good as a product, and that it is excluded from acceptable products. Further, the CPU 6 reads the binarized image data of the binarized image memory 8 for each pixel (step 12), and totals the number of pixels of the binarized image data of "1" in the Y-axis direction, that is, the vertical direction. (Step 13). As shown in FIG. 9, this counting is performed by counting the number of binarized image data of "1" for a pixel group having the same X-axis coordinate value and summing up the number for each X coordinate. Then, by comparing the number of pixels in the Y-axis direction with the number of pixels in the Y-axis direction of the master pattern of a pass product, it is determined whether or not there is a deviation of a certain value or more (step 14).

This shift is determined based on whether or not the number of pixels of the acceptable product is exceeded. Needless to say, the determination may be made based on the difference between the number of pixels of the acceptable product being equal to or less than a certain value or the ratio being equal to or less than a certain ratio. In the determination of the number of pixels, a shift correction in the X-axis direction, which will be described later, may be performed in order to correct a shift between the pixel count distribution of the pattern 10 to be inspected and the pixel count distribution of the master pattern of a good product. In addition, the number of pixels of the master pattern of the accepted product is input and stored in advance, and a plurality of pattern images of the accepted product are stored.
The minimum value, average value, mode value, etc. of the number of 13 pixels are used.

In the inspection processing in steps 12 to 14, the pattern 10 is determined to have a large lack, a drop, a large disconnection, or a large short. In addition, the pattern to be inspected 10...
Is large and the separation into a plurality of parts is mixed, the labeling number of the pattern to be inspected 10...
Although it is determined as a passing product in step 11, this step 12
It can be determined as a defective product by ~ 14.

The expansion process may be performed in steps 12 to 14, or the image data of each pixel (i, j) is sequentially read out from the image memory 4 to determine whether the image data has an appropriate threshold value, for example, the threshold data T or more. No, that is, whether or not it is the pattern image 13 may be determined, and the number of pixels may be totaled in the Y-axis direction, that is, the vertical direction.

FIG. 10 shows another embodiment. This inspection processing is performed as follows.

The above-described expansion processing is performed n times on the pattern image 13 of the frame-shaped pattern to be inspected 10 in the binarized image memory 8 (No.
10 (B)) is superimposed on the previously stored pattern image 13 of the master pattern of the accepted product (FIG. 10 (C)). This overlapping is performed by ORing each binarized image data of the pattern image 13 of the pattern to-be-inspected 10 and each binarized image data of the pattern image 13 of the master pattern of the accepted product for each pixel. It is done by that. Thereafter, the above-described contraction processing is performed n + 1 times (FIG. 10 (D)), and the logical product of the contracted image data and image data obtained by inverting the original image data by “1” and “0” is obtained. As a result, only the defective portion is extracted (FIG. 10 (F)). It is determined whether or not the area of each defective portion is equal to or larger than the allowable value that is acceptable as a passing product.In this case, the pattern image 13 of the master pattern of the passing product is superimposed on the expanded image of the pattern image 13 of the pattern 10 to be inspected. This is because even if there is a variation in the size of each pattern to be inspected 10 and there is a slight displacement, this can be dealt with.

Further, when the expanded image of the pattern image 13 of the pattern to be inspected 10 and the pattern image 13 of the master pattern of the accepted product are overlapped, a process for correcting the displacement is performed. The deviation correction amounts ΔX and ΔY are obtained by the following equations.

ΔX = {(x1 + x2) − (X1 + X2)} / 2 ΔY = {(y1 + y2) − (Y1 + Y2)} / 2 where x1, x2, y1, and y2 are frame-shaped patterns 10 to be inspected.
, And X1, X2, Y1, and Y2 are coordinate values outside the frame-shaped acceptance pattern 10.

Furthermore, the pattern pixel 13 of the master pattern of the passed product is
A logical product of a plurality of accepted pattern images 13
An average pattern image and a mode pattern image are used.

The present invention is not limited to the above embodiment, and can be variously modified without departing from the spirit of the present invention.

[Effects of the Invention] As described in detail above, according to the present invention, the number of pattern images of a pattern to be inspected is counted, and this number is compared with the number of pattern images of a pattern to be inspected that pass. Pass / fail of the inspection pattern is determined. Thus, for example, if the pattern is excessively expanded and short-circuited with an adjacent pattern, the total number of pattern images to be inspected becomes smaller than the number of passed pattern images. If one or more patterns are completely dropped, the total number of pattern images to be inspected is also smaller than the number of passed pattern images. Conversely, if one pattern is broken and separated into a plurality of portions, the total number of pattern images to be inspected becomes larger than the number of passed pattern images. Thus, it can be determined that the product is defective. Also, the number of pixels of the pattern image to be inspected is counted in a specific coordinate direction,
The number of pixels is compared with the number of pixels of the image of the inspected pattern that has passed, and the pass or failure of the inspected pattern is determined. Thereby, if the pattern is partially missing or excessively swollen, the number of pixels of the inspected pattern image is compared with the number of pixels of the passed inspected pattern image,
It is possible to determine that the product is defective, with a small number of parts or a large number of parts. Thus, the inspection of the IC package can be performed more accurately and efficiently.

[Brief description of the drawings]

1 to 10 show an embodiment of the present invention.
FIG. 2 is a perspective view of the IC package, FIG. 2 is an overall circuit diagram of the inspection device, FIG. 3 is a tabulated graph of brightness data of each pixel of the pattern image 13, and FIG. FIG. 5 is a diagram showing binarized image data of a pattern 10 stored in a digitized image memory 8, FIG. 5 is a diagram showing a label number of each pattern 10 stored in a label memory 9, and FIG.
FIG. 7 is a flowchart of an inspection process of patterns 10 of the IC package, and FIGS. 7 to 10 are diagrams showing steps of inspection of the patterns 10. 1, 2 ... IC package, 3 ... CCD camera, 4 ... Image memory, 5 ... Address counter, 6 ... CPU, 7 ...
... density distribution memory, 8 ... binarized image memory, 9 ... label memory, 10 ... pattern, 13 ... pattern image.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-124945 (JP, A) JP-A-1-195350 (JP, A) JP-A-63-118884 (JP, A) (58) Investigation Field (Int.Cl. ⁶ , DB name) H01L 21/66 G01N 21/88

Claims (2)

(57) [Claims] A photographing means for photographing a pattern to be inspected; a distinguishing means for distinguishing an image of a pattern portion from an image other than the pattern portion with respect to the pattern to be inspected photographed by the photographing means; Expansion means for expanding the image of the pattern part toward the image other than the pattern part at the boundary between the image of the pattern part and the image other than the pattern part; and the image of the pattern part and the pattern part expanded by the expansion means Shrinking means for shrinking the image of the pattern portion toward the pattern portion itself at the boundary with other images, and counting means for counting the number of pixels of the pattern image to be inspected shrunk by the shrinking means in a specific coordinate direction. The counting in the specific coordinate direction by the counting means is repeatedly performed along a direction different from the specific coordinate direction. Is allowed, based on the respective numbers of pixels in the specific coordinate direction of the test pattern image, IC package inspection apparatus characterized by comprising discriminating means for discriminating pass or failure of the test pattern. 2. An image of a pattern to be inspected is photographed, and an image of a pattern portion is distinguished from an image other than the pattern portion with respect to the photographed pattern to be inspected. At the boundary between the image of the pattern portion and the image other than the pattern portion, at the boundary between the image of the expanded pattern portion and the image other than the pattern portion, the image of the pattern portion faces the pattern portion itself. The number of pixels of the contracted pattern image to be inspected is counted in a specific coordinate direction, and the counting in the specific coordinate direction is repeatedly executed along a direction different from the specific coordinate direction. The test pattern is determined to be acceptable or defective based on the number of pixels in the specific coordinate direction. IC package inspection method to.