JPH02150704A - Object inspecting device - Google Patents

Abstract

PURPOSE:To eliminate the influence of the disturbance in the peripheral state of an object to be measured and to improve the measuring accuracy of the title device by preparing a height histogram from which the edge section of the object is removed and measuring the height of the object based on the frequency peak of the histogram. CONSTITUTION:After a printed circuit board is placed at a prescribed position, the height of the circuit board is measured with a detecting system 11 and multi-leveled by means of a height picture circuit 13 after the height is processed at a binarization circuit 12. Then a position measuring means 20 and height measuring means 21 prepare a height histogram from a fixed extent of data inputted as pictures and two peak values are detected. Thereafter, the height picture is binarized by using the mean value of the two peak heights as a slice level. Moreover, the dictionary data of chip parts are given and parts positions are detected by pattern matching. After the parts positions are detected, a height histogram from which the edge of chip parts 34 and parts of solder 35 are removed is prepared and the height of the parts 34 can be measured accurately from two peak values.

Description

[Detailed Description of the Invention] [Summary] Regarding an object inspection device, the object is to provide an object inspection device that improves the measurement accuracy of object height, and measures the height of an object to be measured and generates an image signal. An image input means, a binarization means for binarizing an image signal of a certain range including the object to be measured detected by the image input means, and an image signal of a certain range including the object to be measured detected by the image input means. A multi-value conversion means converts the data into multiple values according to the height data, and a binary pattern of the object to be measured that exists within a certain range including the object to be measured is used as the target pattern. A position measurement means that performs butterfly matching by superimposing it on a dictionary pattern corresponding to the regular shape, and then measures the position of the object to be measured, and a histogram calculation is performed from the height data of a certain range including the object to be measured. and a height measuring means for measuring the height of the object to be measured, wherein the height measuring means removes an edge portion of the object to be measured after the position of the object to be measured is measured. The height histogram is created using the above-described method, and the height of the object to be measured is measured based on the frequency peak of the histogram.

[Industrial application field]

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 external appearance of chip components on printed circuit boards inputs a grayscale image of the target component and detects the presence or absence of the component or misalignment based on bright electrode positions. However, this method does not detect the main body of the component, so it has the disadvantage of poor positioning accuracy.

Therefore, the applicant of the present invention has filed an application for a device that eliminates this drawback, and the device related to this prior application measures the three-dimensional shape of the target part and then measures the height of the part.
It is intended to accurately detect the main body of the part. FIG. 6 shows a chip component 2 to be measured located on a printed circuit board 1, and the chip component 2 is attached with solder 3. As shown in FIG. The chip component 2 is divided into a main body 2a and an electrode part 2b, and in particular, the electrode part 2b is soldered. For such a chip component 2, in order to measure the component height,
As shown in FIG. 7, a histogram of height measurement values is created within the limited area 4 including the chip component 2. FIG. 7 is a view of the chip component 2 viewed from above, and the height data (height measurement value ) is obtained, and from this a histogram as shown in FIG. 8 is created using the frequency of each height as a parameter. Then, two peak values are detected from this histogram and taken as the substrate height of the printed board 1 and the component surface height of the chip component 2, respectively.

After that, the difference between these two is determined by the printed board l of chip component 2.
Detected as the height relative to the substrate surface.

[Problem that the invention seeks to solve]

However, in the object inspection device according to the prior application, if solder is attached to the electrode part of the later part more than necessary, when the height histogram is created, There is a problem in that an error occurs in the component height obtained from the two peak values of the substrate and the substrate, and as a result, the measurement accuracy of the component height decreases.

Specifically, what is shown by the solid line ■ in Figure 8 is a normal soldering state, and in this case no error occurs;
As shown in , when the soldering is abnormal, the peak value of the breach 9 is detected as the component surface height, and when the component height measurement calculation is performed based on this, the peak value itself is not accurate. As a result, the measurement accuracy of component height deteriorates. In addition, each height measurement value itself contains errors, so if the two peak values do not accurately correspond to the component surface height and board height, the measurement accuracy will ultimately decrease. do.

The above prior application example is an example of height inspection when a chip component is soldered onto a printed board, but it is not limited to such a printed board, but can also be used to inspect the height of an object on a simple board. A similar problem may occur in other cases.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an object inspection device that can improve the measurement accuracy of object height.

[Means to solve the problem]

In order to achieve the above object, the object inspection apparatus according to the present invention includes an image input means for measuring the height of the object to be measured and generating an image signal, and an image of a certain range including the object to be measured detected by the image input means. Binarization means for converting the signal into binary; multi-value conversion means for converting the image signal in a certain range including the object to be measured detected by the image input means into multiple values according to height data; The target pattern is the binary pattern of the object to be measured that exists within a certain range, and pattern matching is performed by overlaying this with the dictionary pattern corresponding to the regular shape of the object to be measured. In the object inspection apparatus, the object inspection apparatus includes a position measuring means for measuring a position, and a height measuring means for measuring the height of the measured object by performing a histogram calculation from height data of a certain range including the measured object. After the position of the measured object is measured, the height measuring means removes the edge portion of the measured object to create a height histogram, and calculates the height of the measured object based on the frequency peak of the histogram. It is configured to measure.

[Effect]

In the present invention, after the position of the object to be measured is first measured, the edge portion of the object to be measured is removed to create a height histogram, and then the height of the object to be measured is determined based on the frequency peak of the histogram. is measured.

Therefore, by removing the edges of the object to be measured, unnecessary height data such as solder bulges, which are the main cause of errors, can be removed, and the height of the object to be measured can be measured. Improves accuracy.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings.

1 to 5 are diagrams showing an embodiment of the object inspection apparatus according to the present invention, and are examples in which the present invention is applied to height inspection of chip components in ICs.

First, the configuration will be explained. FIG. 1 is a block diagram showing the configuration of an object inspection device. In the figure, the object inspection device includes a detection system 11, a binarization circuit 12, a height image circuit 13, a frame memory 14, a dictionary memory 15, and a matching circuit. 16
, CPU 17, histogram circuit 18 and CRT 19
Consisted of. The detection system (image input means) 11 measures the height around the chip component (certain range) on the printed board of the IC to be measured and inputs it as an image.
It is sent to the value conversion circuit 12 and the height image circuit 13. A binarization circuit (binarization means) 12 binarizes the height image detected by the detection system 11 using a predetermined slice level as a reference, and a height image circuit (multi-value conversion means) 13 converts the height image detected by the detection system 11 into two values. Based on the image data, the image data is multivalued according to the height, and a height image is created from this.

The frame memory 14 stores the binarized image produced by the binarization circuit 12, and particularly stores the binarized pattern of a chip component to be measured as a target pattern. Further, the dictionary memo I month 5 stores a large number of regular shapes and positions of chip parts as dictionary patterns, and dictionary patterns can be input from the outside. The matching circuit 16 reads necessary data from the frame memory 14 and the dictionary memory 15, overlaps the target pattern and the dictionary pattern, and measures the position of the chip component by outputting the number of mismatched pixels. This is done based on orders from. The CPU 17 controls various arithmetic processing instructions necessary for inspecting the position of chip components. For example, it issues a dictionary pattern selection instruction to the dictionary memory 15, and also issues instructions necessary for pattern matching between the CPU 17 and the matching circuit 16. The various alloys are measured and the measurement results are output to the CRT 19. Above frame memory 1
4. Dictionary memory 15, matching circuit 16 and CPU
17 constitutes a position measuring means 20 as a whole.

On the other hand, the histogram circuit 18 performs a histogram operation based on the height data of a certain range including printed boards and chip components based on the output of the height image circuit 13, and sends the data necessary for position measurement of the chip components to the CPU 17. After measuring the position of the chip component, the edge portion of the chip component is removed and a height histogram calculation is performed. At this time, the CPU 17 exchanges data and instructions with the histogram circuit 18, and calculates the height after edge removal. The height of the chip component is measured based on the frequency peak of the histogram, and the measurement result is output to the CRT 19. The CPU 17 and the histogram circuit 18 as a whole are the height measuring means 2.
1. The CRT 19 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 19.

Next, the effect will be explained.

First, a printed board with chip components attached is placed in a predetermined position, the height of a certain range is measured by the detection system 11, inputted as an image, this is binarized by the binarization circuit 12, and the height image is The circuit 13 performs multi-value processing according to the height data.

Next, the program shown in FIG. 2 is executed by the position measuring means 20 and the height measuring means 21. That is, a height histogram is created from a certain range of data input as an image at P. This histogram will be as shown in FIG. 8, for example. Next, two peak values are detected from the histogram at P2. The method for detecting the two peaks is as follows. First, the peak with the highest frequency is defined as the first peak. Next, this height measurer [l/2 of the original height of the part]
Detect the maximum frequency in the area excluding the range of
This is defined as the second peak.

Next, in P3, the average value of the above two peak heights is set as the slice level (in the example of Fig. 8, S/L is set near the middle of the two peaks), and the height image is binarized. do. This binarized image is shown as shown in FIG.

In the figure, 31 is a certain measurement range, 32 is a certain area including the part where chip components are mounted and soldered, and 3
3 is a portion that has been binarized to level [1] at the slice level S/L, and corresponds to a part of the chip component and soldering area. In addition, in the figure, the area other than the hatched area is at the rO] level.

Furthermore, in parallel to step P, dictionary data regarding chip components is provided in step P4. Then, at P, the component position is detected by pattern matching. Specifically, C.P.
In response to the command U17, the target pattern corresponding to the chip component is sent from the frame memory 14 to the matching circuit 16, and a dictionary pattern is read from the dictionary memory 15 and sent to the matching circuit 16 in the same way. The matching circuit 16 overlays the target pattern and the dictionary pattern and measures the number of mismatched pixels.
The pattern will now be checked for matching. Thereby, the position of the chip component is detected.

Next, in P6, the edges of the chip component 34 and the solder portion 35 are removed to create a height histogram, as shown in FIG. Note that 36 is an electrode portion of the chip component 34, and this electrode portion 36 is also removed.

The created histogram will look like Figure 5, which shows the two areas indicated by hatching in Figure 4, namely:
This corresponds to the respective heights of the printed board (substrate) 37 and the chip component 34. Next, at P7, two peaks as shown in FIG. 5 are detected, and the height of the chip component 34 is measured from the difference between the two peaks. In this case, since only data on the component surface and the substrate surface are used, the heights of both are accurately detected, and the height of the chip component 34 can be accurately measured. Therefore, for example, even if the solder is raised more than necessary, as shown by the broken line O in FIG. , the component height can be accurately measured regardless of the solder bulge.

In addition, even if there is some error in the height data, at least the edges and solder parts are removed, so the influence of the error is eliminated as much as possible. Therefore, the above two peak values are accurately calculated from the component surface height and the board height. The accuracy is high in each case.

As a result of the above, the height of the component can be measured accurately, so it is possible to automatically check for defects, such as when a component is installed incorrectly or when the height of the component protrudes due to dirt getting into the bottom of the component. .

Note that the matching process is performed in step P in Figure 2, but this is not done simply to accurately measure the height of the component, but to measure the normal position for inspecting the component. Also used for

Then, by the height measurement and this position measurement as described above, I
Inspection of chip components on the C board is automatically performed.

Further, the application of the present invention is not limited to automatic inspection of the shape, position, etc. of IC parts, but can also be applied to positioning of objects and recognition of objects themselves in other fields.

〔Effect of the invention〕

According to the present invention, the height of an object can be measured with high accuracy 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 flowchart showing its measurement procedure, and FIG. Figure 4 is a diagram showing a binary image of the height data after removing the edges of the part, Figure 5 is a diagram showing its histogram, Figure 6 - Figure 8 is a diagram showing the object inspection device according to the prior application, Figure 6 is a perspective view showing the object to be measured, Figure 7 is a plan view of the object to be measured, and Figure 8 is a histogram of the object to be measured. . 11...Detection system (image input means), 12...
... Binarization circuit (binarization means), 13 ... Height image circuit (multivalue conversion means), 14 ... Frame memory, 15 ... Dictionary Memory, 16... Matching circuit, 17... CPU, 18... Histogram circuit, 19... CRT. 20...Position measuring means, 21...Height measuring means, 31...Measurement range, 32...Constant area, 33... Part, 34...Chip component (object to be measured), 35...
... Solder, 36 ... Electrode section, 37 ... Printed board. Figure 1 Patent Attorney Patent Attorney Igesada Figure 1 Figure 5 A diagram showing the histogram of the first embodiment

Claims (1)

[Claims] Image input means for measuring the height of an object to be measured and generating an image signal; and a binary image signal for binarizing the image signal in a certain range including the object to be measured detected by the image input means. a multi-value converting means for converting into multiple values an image signal in a certain range including the object to be measured detected by the image input means according to height data; Measurement target 2
A position measuring means that uses a value pattern as a target pattern, performs pattern matching by overlaying this with a dictionary pattern corresponding to a regular shape of the target to be measured, and measures the position of the target from this; In an object inspection apparatus, the object inspection apparatus includes a height measuring means for measuring the height of the object to be measured by performing a histogram calculation from height data in a certain range including height data, the height measuring means is configured to measure the height of the object to be measured by Object inspection characterized in that after the object has been measured, edge portions of the object to be measured are removed to create a height histogram, and the height of the object to be measured is measured based on the frequency peak of the histogram. Device.