JPS639602B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shape inspection device, and is particularly suitable for automatically inspecting the quality of minute three-dimensional shapes such as printed board soldered parts, printed board mounted parts, and bumps in LSI bonding. Regarding.

Printed soldering parts, printed board mounting parts,
For industrial products that have minute three-dimensional shapes on a plane, such as LSI bonding bumps, it is necessary to determine whether the minute three-dimensional shapes are good or bad. For example, defects such as excess or deficiency of solder, blowholes, cracks, etc. occur in the soldered portions of printed circuit boards, and these must be detected by determining the shape. For this purpose, conventional methods have been used in which an operator inspects directly visually or using a magnifying glass or a stereomicroscope. However, for example, in the case of soldered parts on printed circuit boards, the surface condition is unstable, such as surface gloss or local cloudiness, making stable inspection difficult. Nakatsuta.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a shape inspection device that can reliably and stably automatically inspect minute three-dimensional shapes.

In order to achieve the above object, the present invention projects a linear slit light onto an object, extracts the light cutting line on the object surface formed by this as electrical information, and extracts the electrical information. The waveform information obtained is subjected to judgment processing based on preset criteria, but even if the surface condition of the object is not uniform, the optical cutting line extracted by preprocessing is corrected. The present invention is characterized in that shape inspection can be carried out reliably.

Hereinafter, the present invention will be explained in detail using the drawings.
FIG. 1 is a configuration diagram of an apparatus showing an embodiment of the present invention, in which a printed board 1 is the object to be inspected.
XY table mechanism such as Y table 2 on which printed board 1 is placed, slit projector 3, image detectors 4, 5,
a head holding structure 6 and a base 7 that hold these;
It is composed of a determination control section 8.

The determination control unit 8 includes optical cutting line extraction circuits 9A, 9B,
Waveform preprocessing circuits 10A, 10B, determination circuit 11,
It is composed of a sequence control circuit 12, an external memory 13, a lamp control circuit 14, a motor control circuit 15, and an external memory 16.

The XY table mechanism includes an X drive motor 17, an Drive motor 2
0, a Y sliding mechanism 21, a Y feeding mechanism (feed screw and nut, not shown), a moving mechanism in the Y direction (horizontal direction on the same page) by a Y table 2, and a printed board holding and positioning mechanism 22. .

In the above configuration, the printed board 1 is carried onto the Y table 2 manually or by an automatic carrying mechanism (not shown), and is positioned and held by the holding and positioning mechanism 22. external memory 1
Reference numeral 6 is, for example, a magnetic tape cassette, a floppy disk, a paper tape, etc., on which the XY coordinates of each soldered portion of the printed circuit board 1 to be inspected are sequentially recorded. The motor control circuit 15 reads this record according to the timing specified by the sequence control circuit 12, moves the XY movement mechanism by driving the motors 17 and 20, and moves the record to the position specified by the external memory 16. Printed board 1
Move and stop sequentially.

FIG. 2 is a diagram showing an example of the configuration of the slit projector 3, which includes a lamp 24, a slit 25, and an imaging lens 26.
The linear slit light from the slit 25 is focused onto the soldering part 23 by an imaging lens 26 as an image 27. In the case of FIG. 2, it is assumed that the slit light is set in the X direction. The image 27 thus obtained is detected by the image detectors 4 and 5 from diagonally above on both sides as shown in FIG. Here, the image detectors 4 and 5 are any type of combination such as a combination of an imaging lens and a television camera, a combination of an imaging lens and an image detector, a combination of an imaging lens and an image scanner such as a galvanometer mirror, and a one-dimensional imaging device. It may also be an imaging device.

FIG. 3a shows the image detector 4 or 5 in this way.
This shows a photosection image detected by . In the figure, it is assumed that the dark portion is actually bright and the output video signal indicates a high voltage. Optical cutting line extraction circuit 9
A and 9B extract the optical cutting waveform as shown in FIG. 3b as described later, and compress the input two-dimensional image data into waveform data.

FIG. 4 is a diagram showing an example of the configuration of the optical cutting line extraction circuits 9A and 9B, showing the video signal V of the image detector 4 or 5, the scanning trigger signal Hd (horizontal synchronization signal in the case of a television camera), and the set value V. ₁ and V ₂ (V ₁ >V ₂ ), and is composed of three elements: a maximum value position detection circuit 28 , a center position detection circuit 29 , and a selection circuit 30 . Its function is to obtain a light section line by scanning a light section image as shown in FIG. Therefore _, for each scan corresponding to a certain X value, as illustrated in _FIG . ), the maximum value position detection circuit 28 determines the Z position Zm. Also the maximum value
When Vm is larger than V ₁ (in the case of Fig. 5b), the center position detection circuit 29 first determines Z = Z ₁ where V = V ₁ , and then determines Z = Z ₂ where V = V ₂ . , and further calculate the center position Z ₀ by setting Z ₀ =(Z ₁ +Z ₂ )/2. Then, during one scan, the center position detection circuit 2
If the video signal V exceeds V ₁ within 9, the selection circuit 30 selects the output Z ₀ of the center position detection circuit 29, and if the video signal V does not exceed V ₁ , the selection circuit 30 selects the maximum value. The output Zm of the position detection circuit 28 is outputted as the position of the optical cutting line. Also, the video signal V
does not exceed V ₂ during one scan, the selection circuit 30 outputs zero (for a more detailed embodiment of this optical cutting line extraction circuit, see Japanese Patent Application No. 1983-
No. 111706 “Shape detection method and device”, patent application
No. 54-146427, "Optical cutting line detection device").

The configuration example shown in Fig. 4 is extremely effective for extracting a light section line from an image with a large surface light selection such as a soldered part and a large change in brightness as a light section image. In the case of a rough object,
The optical cutting line extraction circuit may include only the maximum value position detection circuit 28 or only the center position detection circuit 29.

The waveform preprocessing circuits 10A and 10B perform noise processing on the optically disconnected waveforms extracted by the optically disconnected line extracting circuits 9A and 9B, and connect processing for disconnected portions. FIG. 6 shows an example of its configuration, in which four registers 31,
32, 33, 36 and two comparison circuits 34, 37,
It is composed of two selection circuits 35 and 38. Registers 31 to 33, comparison circuit 34, and selection circuit 35 perform intermediate value filtering processing for noise processing, and register 36, comparison circuit 37, and selection circuit 38 perform step-like interpolation processing for connection of disconnected parts. Do like this.

First, an optical cutting waveform is output as a time series signal from the optical cutting line extraction circuit 9A or 9B, and this is input to the three registers 31, 3.
2 and 33, these are accumulated in sequentially shifted form. Now, as shown in Figure 6, these values are Zi− ₁ ,
When Zi, Zi+ ₁ , the comparison circuit 34 checks the magnitude of these three values, and the selection circuit 35 outputs the intermediate value as the output Zi ₀ . The algorithm for detecting the intermediate value Zi ₀ by the circuits 34 and 35 is shown in FIG.
It is formatted as shown in Figure b.

Next, to connect the broken wire, first use the comparison circuit 37 to connect Zi ₀
=0, and when Zi ₀ ≠0, the value is held in the register 36 and output from the selection circuit 38. When Zi ₀ = 0, register 3
6, the selection circuit 38 selects the value held at that time.
The same value is held in the register 36 as it is. By such step-like interpolation processing, for example, the waveform shown in FIG.
It is formatted as shown in Figure b.

The waveform pre-processing as described above is unnecessary when the object has a stable rough surface, but is essential when the object has optical selection such as a soldering part. Note that the waveform preprocessing is not limited to the intermediate value filtering and step-like interpolation illustrated here, and various methods such as smoothing processing and linear interpolation can be applied.

The outputs from the waveform preprocessing circuits 10A and 10B are judged and evaluated in the judgment circuit 11, and if it is judged as defective, the XY coordinates of the point to be inspected and the type of defect are recorded in the external memory 13. A magnetic cassette tape, floppy disk, paper tape, etc. is used as the external memory 13, and is used as data for correction work by the inspection staff. When the inspection of one inspection point is completed as described above, the next inspection point is moved to the next inspection point according to the data in the memory 16, and inspection is performed.

The content of the judgment made by the judgment circuit 11 varies depending on the object to be inspected and its inspection specifications, but here, as an example, a method for judging whether solder is excessive or insufficient in the soldering surface inspection of a printed circuit board shown in FIG. 10 will be described. Although the determination processing is here performed using a minicomputer or a microcomputer, it can easily be replaced with a dedicated hardware circuit.

Figure 10 a is a good product, b is defective due to excessive solder, c
is an example of a defective solder shortage. For the determination process, first, test areas 39 and 40 shown by broken lines in FIG. 10 are set for each input waveform, and the areas within them, that is, the areas S _A ,
Calculate S _B and set the tolerance value in advance
Compare with S _A0 and S _B0 . As a result, if S _A ≧S _A0 , an excess solder is output, and if S _B ≧S _B0 , an insufficient solder defect is output. Further, this determination is performed on the two optical cutting waveforms detected from the two image detectors 4 and 5, and if a defect is detected in either or both, the soldered portion is determined to be defective. By detecting from both sides simultaneously in this way, even if a blind spot occurs on one side, the other side can be detected correctly, and erroneous determination due to the blind spot can be prevented.

In addition, if the inspection item is a defect that cannot be inspected with just a single slit image, such as the blowhole 41 shown in FIG. 11, the Y table 2 shown in FIG. Then, the slit image is detected and the above judgment process is performed, and by repeating this process, the shape is inspected in an appropriate section in the Y direction, and a comprehensive judgment is made.

The above is a description of the embodiment shown in FIG. However, the slit projector 3, image detector 4,
A fine movement mechanism for focus adjustment is required at the connection between the head holding structure 6 and the head holding structure 6, but this is omitted in FIG. In addition, only one of the image detectors 4 and 5 may be used if there is no risk of creating a blind spot on the object.
In this case, only one pair of optical cutting line extraction circuits 9A, 9B and waveform preprocessing circuits 10A, 10B are required. Further, the angle between the slit projector 3 and the image detector 4 or 5 is practically appropriate to be 45° to 60°, but this value may be appropriately set depending on the purpose. Further, in this embodiment, when a defect is output as a result of the judgment evaluation, it is output to the external memory 13, but a marking device is separately added to mark the part of the object to be inspected that is determined to be defective. It can also be done.

Furthermore, it is also possible in the present invention to determine the mutual arrangement relationship and number of the slit projector and the image detector according to the shapes of the objects 41 and 42 to be inspected, as shown in FIGS. It is included.

As is clear from the above description, according to the present invention, micro three-dimensional shapes, which conventionally had to be relied on manually, can be used in printed board soldering surface inspection, printed board mounting inspection, LSI bonding bump shape inspection, etc. Appearance inspection can be automated, making reliable, stable and efficient inspection possible.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a device showing an embodiment of the present invention, FIG. 2 is a diagram showing an example configuration of a slit floodlight,
FIG. 3 is a diagram showing an example of a light section line from which a detection slit image is extracted, FIG. 4 is a diagram showing an example of the configuration of a light section line extraction circuit, and FIG. 5 is an explanatory diagram of the operation of the circuit in FIG. 4.
Fig. 6 is a diagram showing an example of the configuration of a waveform preprocessing circuit;
8 and 8 are diagrams showing an algorithm for intermediate value filtering processing by the circuit of FIG. 6 and an example of waveform processing using the algorithm, FIG. 9 is a diagram showing an example of disconnection connection processing by the circuit of FIG. 6, and FIG. FIG. 10 is an explanatory diagram showing an example of the defect determination processing method according to the present invention, FIG. 11 is a diagram explaining the state of occurrence of blowholes, and FIG.
The figure shows another example of the structure of the slit projector and image detector in the light cutting method. 1...Printed board, 2...Y table, 3...
Slit projector, 4, 5... Image detector, 9A, 9
B... Optical cutting line extraction circuit, 10A, 10B... Waveform preprocessing circuit, 11... Judgment circuit, 15... Motor control circuit, 17... X drive motor, 19...
Table, 20... Y drive motor, 23... Printed board soldering section, 42... Object to be inspected.

Claims (1)

[Scope of Claims] 1. A slit projector that projects linear slit light onto an object; an image detector that detects a light-cut image drawn on the surface of the object by the slit light;
an extraction means for extracting a linear optical section line from the detected optical section image; a circuit for removing noise from the optical section line extracted by the means; and a connection process for a disconnection in the optical section line. A waveform preprocessing means consisting of at least one of the circuits and a waveform preprocessing means that counts the shape characteristics of the optical cutting line preprocessed by the means and compares it with a preset determination threshold value to determine whether the shape of the object is acceptable or not. and a position setting mechanism that variably sets the relative position of the object with respect to the slit light, and is characterized by a configuration for automatically inspecting the quality of the three-dimensional shape of the object. shape inspection equipment. 2. In the shape inspection device according to claim 1, when inspecting a soldered portion of a printed circuit board, the determining means may detect the What is claimed is: 1. A shape inspection device characterized in that pass/fail determination is made by comparing the area within a region formed by optical cutting lines with a preset reference area.