JPH11281334A - Device for inspecting part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a part inspecting device for always obtaining proper contrast of an image according to the reflectance of the light of a body to be checked and the reflectance of the light of the background or the like. SOLUTION: This distribution histogram for each luminance of picture elements in the area under consideration of the image for the part to be inspected of a body to be inspected is generated. A luminance threshold value Lmax is decided so that the distribution of the picture elements can be the maximum value at the both sides. A difference T-B between a mean value T of luminance higher than a threshold value and a mean value B of luminance lower than the threshold value is obtained as contrast data D. The light quantity of an illuminating means when the contrast data D can be the maximum value is used as an optical condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a component inspection apparatus for optically inspecting semiconductor devices and other electronic components, and more particularly to a component inspection apparatus capable of optimally setting the amount of illumination of an object to be inspected. .

[0002]

2. Description of the Related Art An optical component inspection apparatus is used to inspect the alignment of terminals of semiconductor devices and other electronic components, and the marks printed or imprinted on the devices.
In this component inspection apparatus, there are provided illumination means for illuminating an inspection object such as an electronic component, imaging means for capturing an image of the illuminated inspection object, and display means for displaying the captured image. Based on the image displayed on the means, the inspected object is inspected, for example, for uneven terminals and other inspections.

[0003]

However, when the image photographed by the photographing means is image-processed by the image processing means to inspect, for example, the arrangement of the terminals of the electronic component which is the object to be inspected, the lighting of the illumination is required. If the amount of light is too large or too small, the contrast between the part to be inspected, such as a terminal, and the background becomes unclear, and as a result, accurate image processing data cannot be obtained, making high-precision inspection impossible. Become.

The present invention has been made to solve the above-mentioned conventional problems, and is a component capable of always obtaining an appropriate image contrast in accordance with the reflectance of light of an object to be inspected and the reflectance of light in the background thereof. It is intended to provide an inspection device.

[0005]

According to the present invention, there is provided a component inspecting apparatus for illuminating an object to be inspected and capable of adjusting the amount of light, light amount adjusting means for adjusting the amount of light of the illuminating means, and A photographing unit for photographing an image of the inspection object; and an image processing unit for processing an image photographed by the photographing unit. The image processing unit includes a pixel having a high luminance in an image photographed by the photographing unit. Generating comparison data comparing a group and a pixel group with low luminance, while changing the light amount of the illumination means by the light amount adjustment means, generating the comparison data corresponding to different light amounts, and among the comparison data It is characterized in that an optimum light amount is selected and the light amount when the comparison data is obtained is held as optimum light amount setting information.

According to the present invention, in the image processing means, a group of pixels having a high luminance and a group of pixels having a low luminance are compared, and the amount of light in the illuminating means is adjusted so that the state of comparison is optimized. Therefore, the contrast of the image photographed by the photographing means is optimized, and image processing for the subsequent inspection can be performed reliably.

[0007] The change in the amount of light by the illuminating means may be stepwise or continuous.

For example, the image processing means finds a difference between the average luminance of a high-luminance pixel group corresponding to the image of the inspected object and the average luminance of a low-luminance pixel group corresponding to the background of the image. The difference is used as comparison data for each light amount.

There are various methods for obtaining the optimum comparison data. For example, the comparison data having the maximum difference is determined as the optimum one. Alternatively, when the difference becomes equal to or more than a predetermined value, any of data having a value equal to or more than a predetermined value may be selected as optimal comparison data.

The peak of the comparison data is not the difference between the average luminance of the pixel group with high luminance and the average luminance of the pixel group with low luminance, but the distribution of the number of pixels of the pixel group with high luminance. The difference between the luminance value and the luminance value at which the distribution of the number of pixels of the low-luminance pixel group has a peak may be used.

When the inspected object has a plurality of inspected portions, the image processing means obtains comparison data of the inspected portions at the inspected object for each light amount, and calculates an average value thereof. The average value can be used as comparison data for each light amount.

By performing this processing, it is possible to easily and quickly set the light amount at which the contrast of a plurality of inspected portions becomes good.

It is to be noted that, as described below, it is possible to set the light amount of the illuminating means adjacent to each of the inspected portions to be optimum so that the contrast of the image of each of the inspected portions becomes optimum.

That is, while changing the light amount of the illuminating means which is close to one of the inspected parts of the inspected body having the plurality of inspected parts,
Generate the comparison data for the part to be inspected and select the most appropriate one of the comparison data and set the light amount when the comparison data is obtained as the optimal light amount setting information corresponding to the inspected part, Next, while changing the light amount of the illuminating means adjacent to the other one inspected portion, the optimum light amount setting information for the other one inspected portion is similarly obtained, and the optimum light amount setting information for all the inspected portions is obtained. After the light quantity setting information is obtained, the light sources are simultaneously illuminated by the illumination means close to all the inspected parts based on the light quantity setting information, and while the light quantities of all the illumination means are reduced, the different light quantities corresponding to all the inspected parts are obtained. The average value of the comparison data for each light amount is obtained, and the time when this average value becomes the optimum comparison data can be held as the optimum light amount setting condition of each lighting unit.

Further, in the above, when calculating an average value of comparison data of a plurality of inspected portions, a pixel having a high luminance corresponding to an image of the inspected object in comparison data of any one of the inspected portions. When the difference between the average luminance of the group and the average luminance of the low-luminance pixel group corresponding to the background of the image is equal to or smaller than the threshold value, it is preferable that this comparison data is not used as optimal data.

In this way, even if the average value of the comparison data is optimal, if the data at any point is not too optimal, the data can be ignored.

Next, when the number of pixels having the highest luminance is equal to or more than a predetermined value, it is preferable not to use the comparison data at that time.

This is when the input signal of the photographing means such as a CCD camera is saturated. By ignoring this data, the occurrence of excessive contrast can be prevented.

[0019]

FIG. 1 is a block diagram showing the entire structure of a component inspection apparatus according to the present invention, FIG.
FIG. 3 is a perspective view of the lighting means. A component inspection apparatus shown in FIG. 1 includes an illumination unit 1, a photographing unit 2 such as a CCD camera for photographing an image of an inspection object (work) W illuminated by the illumination unit 1, and a light amount of the illumination unit 1. And an image processing means (image processing device) 4 for processing an image photographed by the photographing means 2.
The light amount adjusting means 3 is controlled by an image processing means 4.

An image photographed by the photographing means 2 and processed by the image processing device 4 is displayed on a display means (display device) 5. Reference numeral 6 denotes an input device for operating a computer serving as the image processing means 4. As shown in FIGS. 2 and 3, the lighting means 1 has a box-shaped case 10, and the case 10 is provided with a connector 11 for connecting to the light amount adjusting means 3.

The case 10 has a window 12 penetrating vertically. When the case 10 is lowered from the state shown in FIG. 3 so as to cover the test object W with the case 10, the test object W located thereunder can be seen through the window 12 from above the case 10. The photographing unit 2 faces the inspection object W from above the window 12.

In the case 10 of the illuminating means 1, an upper illuminator 13, a middle illuminator 14, and a lower illuminator 15 are provided. The upper illuminating body 13 gives light to the inspected object W from directly above, and is provided at four locations around the window 12 as shown by 13a, 13b, 13c, and 13d. The middle illuminating body 14 applies light to the inspected body W obliquely from above by 45 degrees, and is provided at four locations around the window 12 as shown by 14a, 14b, 14c, and 14d. The lower illuminating body 15 is provided vertically on the side of the inspected object W, and the light is given to the inspected object W horizontally from the side. The lower illuminating body 15 is provided at four locations around the window 12 as shown by 15a, 15b, 15c, and 15d.

The device under test W shown in FIGS. 2 and 3 is a semiconductor device (IC) and has terminals W1, W2, W in four directions.
3, W4 protrude. In this embodiment, the lighting bodies 13a, 14a, and 15a approach the terminal W1, the lighting bodies 13b, 14b, and 15b approach the terminal W2, and the lighting bodies 13c, 14c, and 15c approach the terminal W3. And the lighting bodies 13d, 14d, and 15d are close to the terminal W4.
Further, a mark Wa is printed or engraved on the upper surface of the inspected object W as another inspected portion.

Next, a description will be given of a method of adjusting the illumination luminance in the above-described component inspection apparatus. FIG. 5 is a flowchart for explaining the method of adjusting the illumination luminance. The inspected object W is photographed by the photographing means 2 through the window 12 opened in the case 10 of the lighting means 1, and its image is displayed on the display means 5 and image-processed by the image processing means 4.

In this image processing, an attention area is set in the image photographed by the photographing means 2 as shown in ST1 (step 1) of FIG. This attention area is shown in FIG. In FIG. 2, the attention areas are indicated by,,,. In the image processing, windows are set in the regions of interest,. The noted area includes a terminal W1, a terminal W2, a terminal W3,
Denotes a terminal W4, and denotes a mark Wa portion.

First, in ST 2, the light amount of each illuminating body of the illuminating means 1 is set by the light amount adjusting means 3. ST
At 3, the noted areas of the photographed image of the inspection object W at this light amount are taken into the image processing means 4 simultaneously or individually. In ST4, a luminance histogram is measured for the attention area, and the difference between the high luminance and the low luminance is stored as comparison data in the histogram. Next, in ST5, the light amount adjusting means 3 monitors whether or not all changes in the light amount of each illuminating body of the illuminating means 1 have been completed. If not, the light amount of illumination is changed in ST2, and ST3 and ST4 are executed. Repeated. ST5
In S, when it is determined that the measurement of the histogram and the holding of the comparison data under all light quantity conditions are completed,
At T6, the respective data are compared to determine an optimal light amount condition. In ST7, the illumination light amount of the illumination means 1 is set based on the optimal conditions.

Thereafter, illumination is performed on the object to be inspected W under the optimized conditions.
Is processed, and it is determined, for example, whether or not there is an irregularity in each terminal, or whether or not the mark Wa is reliably marked. While the same inspection object W is being inspected, the light amount of the illumination means 1 may always be set to the same value, or the flow shown in FIG. 5 may be always performed, or may be performed intermittently. The lighting conditions may be changed as needed.

Next, the method of adjusting the illumination luminance will be described in detail. (ST4: Luminance Histogram Measurement) The image processing means 4 obtains a distribution as shown in FIG. 4 from the relationship between the luminance and the number of pixels in one region of interest in the image photographed by the photographing means 2. The luminance is converted into 8-bit (256 gradations) two-dimensional data, the number of pixel distributions is determined for each luminance, and a histogram is generated. FIG. 4 shows an example of the histogram.

Next, a luminance threshold value Lmax is obtained from the histogram shown in FIG. In the histogram shown in FIG.
When one of the luminances is set as the threshold L and the pixel distribution is divided into two groups, a threshold Lmax at which the variance of the number of pixels in the two groups is maximized is determined. That is, the threshold L
The value of L at which the cumulative number of pixels with lower luminance than the threshold value and the cumulative number of pixels with higher luminance than the threshold value L are the largest is Lma.
x. The pixel group in a region where the luminance is higher than the luminance threshold Lmax corresponds to, for example, an image of a portion to be inspected in which light is reflected by a terminal of the inspected object W or light is reflected by a mark Wa. The pixel group in a region whose luminance is lower than the threshold value Lmax corresponds to the background image of the terminal or the background image around the mark Wa.

Next, from the histogram shown in FIG. 4, an average value of the luminance is obtained from the total (cumulative) luminance of the pixels in the region higher than the luminance threshold Lmax, and this average value is set as the average luminance T. Similarly, an average value of the luminance is obtained from the sum (accumulated) of the luminance of the pixels in the area lower than the luminance threshold Lmax, and this average value is set as the average luminance B. The difference D = T−B of the average luminance is set as comparison data of each attention area.

(ST6: Optimization Condition) When the comparison data (difference in average luminance D = T−B) is equal to or larger than a predetermined value, the data is determined as the best data. In this embodiment, when the comparison data D has the maximum value, the image processing unit 4 determines that the contrast between the inspected portion and the background is the best. It should be noted that in FIG.
The difference between the luminance when t appears and the luminance when the peak Pb of the distribution of the number of pixels in the low luminance area appears may be used as the comparison data.

In the histogram shown in FIG.
The ratio of the number of pixels having the highest luminance (255 gradations in FIG. 4) to the whole is defined as the maximum luminance occupancy R. When the maximum luminance occupancy R is equal to or more than a predetermined value (for example, 10%), a CCD camera or the like is used. It is determined that the light input of the photographing means 2 is in a saturated state.

(Batch adjustment of all illuminating bodies) As a method of adjusting the light amount of each illuminating body of the illuminating means 1 based on the histogram shown in FIG. 4, the contrast of all the attention areas,. As described above, there is a method of adjusting the light amounts of all the illuminators at once. In this method, for example, all the illuminating bodies are temporarily turned off, and the illuminating body 13 (13a, 1
3b, 13c and 13d) are gradually increased at the same time. When the light quantity of the illuminating body can be set at, for example, 5 bits (32 steps), the light quantity of all the upper illuminating bodies 13 is increased by one step, two steps, three steps, or four steps. Then, for each light amount set by all the lighting bodies 13 in the upper stage, the respective attention areas,.
Separately, comparison data (difference in average luminance D = T−B) is obtained from the histogram shown in FIG.
The average value Da of each comparison data D is obtained. At this time, if the comparison data D is extremely small and is smaller than the threshold value CT in any one of the attention areas, this data is ignored.

The above evaluation is performed for each light amount while increasing the light amount of the upper illuminating body 13 stepwise. Next, the upper illuminating body 13 is turned off, and the middle illuminating body 1 is turned off.
4 (14a, 14b, 14c, 14d) are all turned on at the same time, and the light quantity of all the middle illuminators 14 is increased in a predetermined stage as described above. Next, the upper illuminating body 13 and the middle illuminating body 14 are turned off, and all the lower illuminating bodies 15 (1
5a, 15b, 15c, 15d) are turned on, and the light amounts of all lower illuminating bodies 15 are simultaneously increased in a predetermined stage.

The average value Da of the comparison data D is obtained for all cases when the lower, middle, and upper illuminators illuminate with respective light amounts. However, the average value Da used is limited to those satisfying the following conditions. Condition 1: There is no comparison data D of all the attention areas that is equal to or less than the threshold CT. Condition 2: Among the comparison data D of all attention areas, the maximum luminance occupancy R is equal to or less than a predetermined value. There is,

The maximum value Da of the average values Da at the respective light amounts using the comparison data satisfying the above conditions.
max is set as an optimum light amount setting condition. Image processing means 4
Then, the illuminating body illuminated when the maximum value Damax is obtained and the light amount at that time are stored as optimum light amount setting conditions, and the light amount under the optimum condition is set for the inspection object W. The image illuminated by the illuminating means 1 and the image captured by the imaging means 2 are processed to inspect the terminals W1, W2, W3, W4 for irregularity or bending, or a defect of the mark Wa.

In the above description, only the upper illuminator is turned on with the light level changed, then only the middle illuminator is turned on with the light level changed, and then only the lower illuminator is changed in light level. Is turned on, but all or two stages of lighting bodies are turned on, the light amount is randomly changed, and the average value Da is obtained for each light amount, and the maximum value Dam is obtained.
ax may be used as the best contrast data. In addition,
Instead of increasing the amount of light of the illuminating body stepwise, the amount of light may be increased continuously, and comparison data may be created for each amount of light at predetermined intervals.

(Individual Adjustment of Each Illuminating Object) It is also possible to individually set and adjust the amount of illumination light to each of the attention areas,. First, in a state where the illuminating bodies other than the illuminating bodies 13a, 14a, and 15a close to the attention area where the terminal W1 exists are turned off, the light amount of only the illuminating body 13a is gradually increased. The light is turned on by changing the light amount of only 14a stepwise, and then the illuminating body 15a
Lighting is performed by changing only the light amount in a stepwise (or continuous) manner. For each light amount of each illuminator, comparison data (difference in average luminance D
= T−B), but in this comparison data, only those satisfying the above condition 2 are used. Then, the data having the maximum value of the comparison data D in the attention area is set as the optimum light amount condition in the attention area.

In the same manner as described above, the amount of light of the illuminating body is individually changed for all the illuminations in the vicinity of the attention areas of the terminals W2, W3, and W4, and the optimum comparison data, that is, the comparison data D Find the maximum value of. When the optimum contrast data is obtained for all the terminals W1, W2, W3, and W4, all the illuminators are turned on at the same time with the light amount at which the optimum comparison data was obtained. When all the illuminators are turned on, the subject W is over-illuminated. Therefore, while reducing the light amounts of all the illuminating objects by one level (or continuously decreasing them), each attention area including the mark Wa for every light amount until the light is turned off.
,,, Are calculated. Then, when the maximum value Damax of the average value is obtained,
The best light amount setting condition is used.

[0040]

As described above, according to the present invention, an optimum illumination condition can be calculated in the component inspection apparatus. By illuminating the object to be inspected under appropriate conditions, it becomes possible to optimally inspect parts and the like using image processing.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of a component inspection apparatus according to the present invention;

FIG. 2 is a plan view of a lighting unit,

FIG. 3 is a perspective view of a lighting unit,

FIG. 4 is a diagram illustrating a luminance histogram;

FIG. 5 is a flowchart showing a procedure for setting the luminance of the lighting unit;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Illumination means 2 Imaging means 3 Light quantity adjustment means 4 Image processing means 5 Display means 10 Case 12 Window 13 Upper illuminator 14 Middle illuminator 15 Lower illuminator W Inspection object

Claims (7)

[Claims] An illumination unit configured to illuminate an object to be inspected and to adjust a light amount; a light amount adjustment unit to adjust a light amount of the illumination unit; a photographing unit to photograph an image of the object to be inspected; Image processing means for processing an image photographed by the photographing means, wherein the image processing means contrasts a high-luminance pixel group and a low-luminance pixel group in the image photographed by the photographing means. Data is generated, while changing the light amount of the illumination means by the light amount adjusting means, the comparison data corresponding to different light amounts is generated, and an optimum one of the comparison data is selected, and the comparison data is selected. A component inspection apparatus characterized in that the obtained light amount is held as optimal light amount setting information. 2. The image processing means calculates a difference between an average luminance of a high-luminance pixel group corresponding to an image of an object to be inspected and an average luminance of a low-luminance pixel group corresponding to an image background.
2. The component inspection apparatus according to claim 1, wherein the difference is used as comparison data for each light amount. 3. The component inspection apparatus according to claim 2, wherein the comparison data having the maximum difference is optimized. 4. The image processing means obtains comparison data of a plurality of parts to be inspected on an object to be inspected for each light amount, calculates an average value thereof, and uses the average value as comparison data at each light amount. The component inspection apparatus according to claim 2. 5. The image processing device according to claim 1, wherein the light amount of the illumination means which is close to one of the inspected portions of the inspected object having the plurality of inspected portions is changed. Generate the comparison data, select the most appropriate one of the comparison data, and set the light amount when the comparison data is obtained as the optimum light amount setting information corresponding to the inspected portion. While changing the light amount of the illuminating means close to the part to be inspected, the optimum light amount setting information for the other one part to be inspected is similarly obtained, and the optimum light amount setting information for all the parts to be inspected can be obtained. After that, based on the light amount setting information, the illumination units adjacent to all the inspection units are simultaneously illuminated, and while reducing the light amounts of all the illumination units, the comparison data of the different light amounts corresponding to all the inspection units are reduced. average 4. The component inspection apparatus according to claim 2, wherein a value is obtained, and a time when the average value becomes optimum comparison data is held as an optimum light amount setting condition of each lighting unit. 6. When calculating an average value of comparison data of a plurality of inspected portions, an average of a group of pixels having high luminance corresponding to an image of the inspected object in comparison data of any one of the inspected portions. The component inspection apparatus according to claim 4, wherein the comparison data is not used as optimal data when a difference between the luminance and an average luminance of a low-luminance pixel group corresponding to a background of the image is equal to or smaller than a threshold. 7. The component inspection apparatus according to claim 1, wherein when the number of pixels having the highest luminance is equal to or more than a predetermined value, the comparison data at that time is not used.