JPH02165004A - Object testing apparatus - Google Patents

Abstract

PURPOSE:To improve detecting accuracy of the position of an object even when the peripheral state of said object is disturbed by lexicographically scanning the matching of brightness and height of said object through equalization of the lexicographic position, operating the coincidence therebetween and measuring the position of said object based on said value of coincidence. CONSTITUTION:In response to an instruction from a CPU, an objective pattern 32 for electrode in a limited measuring range 31 is sent from an objective pattern memory 21 to a matching unit 22. At the same time, a lexicographic pattern 34 for electrode corresponding to an electrode part 2b of a chip 2 is read from a lexicographic pattern memory 23 and sent to the matching unit 22. The patterns 32 and 34 are read out at the matching unit 22 and sent to the matching unit 22. At the matching unit 22, the lexicographic positions are made equal to overlap the patterns 32 and 34. Then, the number of pixels where the patterns do not agree is measured, thereby detecting disagreement of the patterns. The overlapping position can be controllable from outside. Since the pattern from which the part of a solder 3 is removed on the basis of the brightness image is used, the lengthwise position and the widthwise position of an object 2 can be obtained from the height image.

Description

[Detailed description of the invention]

[Table of Contents] Overview Industrial Application Fields Prior Art (Fig. 65) Problems to be Solved by the Invention Examples of Means and Actions for Solving the Problems One Embodiment of the Present Invention (Figs. 1 to 5) Effects of the Invention [Summary] The purpose of the present invention is to provide an object inspection device that can improve the accuracy of measuring the position of an object even when the surrounding state of the object is disturbed. An image input means that detects information and height information and generates an image signal, and two brightness images of a certain range including the object to be measured detected by the image input means.
A first binarization means for converting into a value, a second binarization means for binarizing a height image of a certain range including the object to be measured detected by the image input means, dictionary information storage means for storing brightness and height corresponding to the shape of the object as a dictionary pattern; Then, pattern matching is performed by overlaying these target patterns with dictionary patterns, and during the pattern matching, dictionary scanning is performed with the dictionary positions being the same for the brightness and height matching, and the matching degree of both is calculated. and a position measuring means for calculating the position of the object to be measured based on the calculated value. [Industrial Field of Application] The present invention relates to an object inspection device, and more particularly, to an object inspection device suitable for use in pattern recognition of components mounted on IC chips and the like. In recent years, surface-mounted components (chip components) have come into widespread use in order to miniaturize electronic devices. It is predicted that the use of chip components will continue to advance and the number of chips will increase rapidly in the future. In the process of manufacturing printed circuit boards using chip components, mounting is performed by automatic machines. However, automation of the external appearance inspection of the mounted state has been delayed, and the current situation is that it relies on human visual inspection. Automation of visual inspection is essential to improve the reliability of printed circuit boards using chip components. Against this background, there is a strong desire to automate the visual inspection of chip component mounting. [Conventional technology] Conventional object inspection equipment that automatically inspects the appearance of chip components on printed circuit boards inputs a grayscale image of the target component and detects the presence or absence of components or misalignment based on bright electrode positions. are doing. However, since this method does not detect the object itself, it has the disadvantage of poor positioning accuracy. Therefore, the present applicant has filed an application for a device to eliminate this drawback, and the device related to this earlier application has the disadvantage of poor positioning accuracy. After measuring the three-dimensional shape, the height of the component is measured to accurately detect the position of the component. Figure 6 shows the chip component to be measured located on the printed board 1. 2, the chip component 2 is attached by solder 3. The chip component 2 is divided into a main body 2a and an electrode part 2b, and the electrode part 2b is particularly soldered.About such a chip component 2 In order to measure the height of a component, for example, a spot light is irradiated from above the chip component 2 and the reflected light is detected from an oblique direction tilted at a predetermined angle to obtain height data (height measurement value) of the chip component 2, etc. A histogram is created using the frequency of each height as a parameter, and the height of the chip component 2 relative to the printed board 1 is detected from this.By detecting such a component height, the height of the chip component 2 is calculated. [Problem to be solved by the invention] However, in the object inspection device according to the prior application, if soldering is done before, the position cannot be accurately determined based on the height of the component. It can be measured, but when soldering, if more solder adheres to the electrode part of the later part than necessary and it rises further from the electrode, there will be an error in the part height, especially if the longitudinal position of the part is not accurate. However, the above prior application is an example of height inspection when chip components are soldered onto a printed board; Similar problems can occur not only when inspecting the position of an object on a board, but also when inspecting the position of an object on a board. Therefore, the present invention is designed to detect objects even when the surrounding state of the object is disturbed. An object of the present invention is to provide an object inspection device that can improve the accuracy of measuring the position of a target object. an image input means that detects height information and generates an image signal; a first binarization means that binarizes a brightness image in a certain range including the object to be measured detected by the image human power means; a second binarization means that binarizes a height image in a certain range including the object to be measured detected by the input means; and a dictionary pattern that determines the brightness and height corresponding to the regular shape of the object to be measured A dictionary information storage means for storing the object as a target pattern, and a binary pattern of the brightness and height of the object to be measured existing within a certain range including the object to be measured as the object pattern, and these object patterns are superimposed on the dictionary pattern. Pattern matching is performed, and during the pattern matching, the brightness and height matching is performed with the dictionary positions being made the same and dictionary scanning is performed.
), and a position measuring means for calculating the degree of coincidence between the two and measuring the position of the object to be measured based on the calculated value. [Operation] In the present invention, the binarized brightness and height patterns of the object to be measured that exist within a certain range including the object to be measured are taken as target patterns, and these target patterns are superimposed on dictionary patterns to create a pattern map. At the same time, during pattern matching, the matching of brightness and height is scanned in the dictionary with the same dictionary position, the degree of coincidence of both is calculated from this, and the position of the object to be measured is determined based on the calculated value. is measured. Therefore, the height image can be used to accurately determine the position of the object in one direction, and the brightness image can be used to accurately determine the position in the other direction. Even if there is, the accuracy of measuring the position of the object to be measured is improved. [Example] The present invention will be described below based on the drawings. 1 to 5 are diagrams showing an embodiment of an object inspection device according to the present invention, and are examples in which the present invention is applied to inspecting the position of chip components in an IC. First, the configuration will be explained. FIG. 1 is a block diagram showing the configuration of the object inspection device. Matching circuit 16
, height matching circuit 17, arithmetic circuit 18, CPU 19
, and a CRT 20. The detection system (image manual means) 11 inputs an image of the periphery (certain range) of the chip component on the printed board of the IC to be measured, including height information and brightness information, and converts the image into the binarization circuit 12, Send to 3. A binarization circuit (first binarization means) 12 is a detection system 11
Among the brightness images detected in , a brightness image in particular is di-sulfurized using a predetermined slice level corresponding to a certain brightness as a reference. The slice level at this time is set in advance, and is a value that allows discrimination between the component body and the electrode portion of the chip component. Further, the binarization circuit (second binarization means) 13 is connected to the detection system 1
Among the height images detected in step 1, the height image in particular is binarized using a predetermined slice level corresponding to a certain height as a reference. The brightness dictionary memory 14 stores a large number of regular shapes of chip components as dictionary patterns corresponding to brightness data, and it is possible to input dictionary patterns manually from the outside. The height dictionary memory 15 similarly stores a large number of regular heights of chip components as dictionary patterns corresponding to height data, and this can also be done manually by inputting dictionary patterns from outside. As shown in FIG. 2, the brightness matching circuit 16 has an object pattern memory 21 and a matching section 22 therein, and the object pattern memory 21 stores the binarized image in the binarization circuit 12, and in particular, For the target chip component, its binarized pattern is stored as the target pattern. In FIG. 2, the dictionary pattern memory 23 corresponds to the brightness dictionary memo January 4. The matching section 22 includes the target pattern memory 21 and the matching section 2.
The position of the chip component is measured by reading out the necessary data from 2, superimposing the target pattern and dictionary pattern, and outputting the number of mismatched pixels.
This is done based on orders from 9. On the other hand, the internal configuration of the height matching circuit 17 is the same as that in FIG. 2 (not shown).
, superimpose the target pattern and the dictionary pattern for the height of the chip component based on the same command from the CPU 19,
The height of the chip component is measured by outputting the number of mismatched pixels. The calculation circuit 18 calculates the position of the chip component from the brightness matching mismatch data and the height matching mismatch data based on the outputs (matching results) from the brightness matching circuit 16 and the height matching circuit 17, and sends this information to the CPU 19. Output. The CPU 19 controls various arithmetic processing instructions necessary for inspecting the position of chip components, such as the brightness dictionary memory 14.
, issues a dictionary pattern selection command to the height dictionary memory 15, and also exchanges various commands necessary for pattern matching with the brightness matching circuit 16 and height matching circuit 17, and performs measurement. Results on CRT20
Output to. The CRT 20 displays the measurement results of the positions and heights of chip components externally. A printer or the like may be used instead of the CRT 20. The brightness dictionary memory 14 and the height dictionary memory 15 collectively constitute a dictionary information storage means 24, which includes a brightness matching circuit 16, a height matching circuit 17, and an arithmetic circuit 1.
8 and the CPU 19 constitute a position measuring means 25 as a whole. Next, the effect will be explained. FIG. 3 is a flowchart for measuring the position of a chip component. The object to be measured in this example is the 6th one shown as an example of the prior application.
It is similar to the one shown in the figure. First, in step p+z, the printed board 1 to which the chip component 2 is attached is placed at a predetermined position, and the detection system 11 images a certain range including brightness and height information to input the image. Here, as the chip component 2, for example, a black resistor is used, and in particular, the surface of the main body 2a is black and appears dark (reflected), while the electrode portion 2b has a metal surface and appears bright. Therefore, the brightness image is as shown in FIG. ), in a certain measurement range 31 on the printed board 1, the main body 2a of the chip component 2 is the darkest, then the solder 3 part gradually becomes darker according to the inclination angle, and then the part of the printed board 1 becomes darker. In addition, the electrode portion 2b reflects a large amount of light, resulting in a bright image.From this, it can be seen that only the electrode portion 2b can be distinguished from the brightness image.On the other hand, the height image is as shown in Fig. 5(a). In a certain measurement range 31, a part of the chip component 2 and the solder 3 is high, and a part of the printed board 1 is low according to the slope. However, it is difficult to draw accurately in the figure. Therefore, the solder 3 part is the chip part 2.
It is drawn in the same way. Next, in step P2, these brightness images and height images are binarized. The binarized brightness image is the fourth one.
As shown in Figure (b), the part corresponding to the electrode part 2b (
Only 32 (hereinafter referred to as electrode target pattern) is bright [1
] level, others are dark (0) level. On the other hand, the binarized height image is shown as shown in FIG. 5(b), and only the part 33 corresponding to the chip component 2 and solder 3 (hereinafter referred to as component target pattern) is bright at [1] level. , others are dark

[0] level. Further, in parallel with step P2, dictionary data regarding the chip component (in this case, the black resistor) is given in P3, and among the dictionary data, those corresponding to the brightness data are shown as shown in FIG. Part 2b
(hereinafter referred to as electrode dictionary pattern) 34
The area is at bright [1] level, and the other area (portion of printed board 1) is at dark (0) level. Further, among the dictionary data, those corresponding to the height data are shown as shown in FIG. , and others (the portion of the printed board 1) are at the dark [0] level. In this case, since the size of the chip component 2 is known, the size becomes an accurate dictionary pattern for matching. Next, in step P4, pattern matching is performed by overlapping the target patterns 32, 33 and the dictionary patterns 34, 35 with respect to brightness and height, respectively. - As an example, a specific method of pattern matching for brightness is shown in FIG. That is,
According to a command from the CPU 19, the electrode target pattern 32 in the measurement range 31 limited as described above is sent from the target pattern memory 21 to the matching section 22, and the electrode dictionary pattern corresponding to the electrode part 2b of the chip component 2 is sent from the dictionary pattern memory 23. 34 is read out and similarly sent to the matching section 22. The matching section 22 overlays the electrode target pattern 32 and the electrode dictionary pattern 34, counts the number of mismatched pixels, and detects whether these patterns match. In this case, the dictionary scanning method uses, for example, the usual rask scan method or spiral method. Further, the position (x, y) of the superposition of both can be controlled from the outside. For example, in this embodiment, since the approximate position of the electrode section 2b can be easily determined from the brightness image, this position (x, y) can be controlled from the outside.
, y). In this way, pattern matching regarding brightness is performed. Pattern matching for height is also performed using a similar method. Note that, in practice, each dictionary is scanned at the same time. Then, based on the results of scanning each dictionary, the following calculation is performed. C=αA+βB ・−・・・■ However, A: Inconsistency degree of brightness matching B: Inconsistency degree of height matching α, β: Coefficient C: Total inconsistency degree 0 Dictionary position where C is the minimum from the calculation result of formula When , the target pattern and the dictionary pattern are the best match in terms of brightness and height, and this is the part position. Therefore, according to such a method, since the pattern excluding the solder 3 portion is used based on the brightness image, the longitudinal position of the chip component 2 can be accurately determined.
Furthermore, the widthwise position of the chip component 2 can be accurately determined based on the height image. As a result, for example, even if solder adheres to the electrode portion 2b of the chip component 2 more than necessary and swells up, the width and length of the electrode portion 2b of the chip component 2 may be reduced during soldering. (distance in the longitudinal direction) can be accurately determined, and the longitudinal position of the chip component 2 can be determined extremely accurately compared to the example of the prior application, and the measurement accuracy of the component position can be improved. Note that the above is a case where the solder condition is disordered, but it is not limited to this, and the chip component 2 is caused by dust etc. adhering to the solder part.
A similar effect occurs when the surrounding state of Furthermore, the present invention is not limited to processing in which brightness and height are matched at the same time as in the above-mentioned embodiments; for example, after matching is performed by height, scanning is performed in the longitudinal direction of the part by brightness. You can do it like this. Further, the application of the present invention is not limited to automatic inspection of the position of IC parts, etc., but can also be applied to positioning of objects and recognition of objects themselves in other fields. [Effects of the Invention] According to the present invention, it is possible to improve the accuracy of measuring the position of an object even when the surrounding state of the object is disturbed.

[Brief explanation of the drawing]

1 to 5 are diagrams showing an embodiment of the object inspection device according to the present invention, FIG. 1 is a block diagram showing its configuration, FIG. 2 is a block diagram of its matching circuit, and FIG. 3 is its matching circuit. A flowchart showing the measurement procedure, FIG. 4 is a diagram showing pattern characteristics regarding the brightness data, FIG. 5 is a diagram showing pattern characteristics regarding the height data, and FIG. 6 is a diagram showing the pattern characteristics regarding the height data. FIG. 3 is a perspective view showing a measurement target. 1... Printed board, 2... Chip parts, 2a... Main body, 2b... Electrode section, 3... Solder, 11. ...Detection system (image input means), 12...
...Binarization circuit (first binarization means), 13...
...Binarization circuit (second binarization means), 14...
・Brightness dictionary memory, 15...Height dictionary memory, 16...Brightness matching circuit, 17...
... Height matching circuit, 18 ... Arithmetic circuit, 19 ... CPU. 20...CRT. 24... Dictionary information storage means, 25... Position measuring means, 31... Measurement range, 32... Electrode target pattern, 33... - Component target pattern, 34...electrode dictionary pattern, 35...component dictionary pattern. A block diagram of a matching circuit according to one embodiment. FIG. 2 A diagram showing pattern characteristics for brightness data in one embodiment. FIG. 4 A flowchart showing measurement procedures in one embodiment. Figure 5 showing pattern characteristics

Claims (1)

[Claims] Image input means for detecting brightness information and height information about an object to be measured and generating an image signal, and a brightness image of a certain range including the object to be measured detected by the image input means. 2
a first binarization means for converting into a value, a second binarization means for binarizing a height image of a certain range including the object to be measured detected by the image input means, and a normalization for the object to be measured. dictionary information storage means for storing brightness and height corresponding to the shape of the object as a dictionary pattern; year,
These target patterns are superimposed on dictionary patterns to perform pattern matching, and in the pattern matching, the brightness and height matching is performed by scanning the dictionary with the dictionary positions being the same,
An object inspection device comprising: a position measuring means for calculating the degree of coincidence between the two and measuring the position of the object to be measured based on the calculated value.