JPH01129108A - Detecting device of sectional shape - Google Patents

Abstract

PURPOSE:To detect a sectional shape with excellent accuracy and at high speed, by a method wherein an output of a strip-shaped line sensor detecting a light-cut linear image of a conductor part is masked with an output of another line sensor in a substrate element, so as to obtain a required detection output signal. CONSTITUTION:A non-diffused light-cut linear image 19A formed corresponding to a conductor element 20, out of two-dimensional patterns on an imaging surface 17 based on the reflected light from a printed wiring board 12, which is caused by the application of a laser light, is detected by a strip-shaped line sensor 18 which is provided at a position (h) from a height corresponding to a substrate element. Meanwhile, a diffused light-cut linear image 19B formed corresponding to the substrate element is detected by a line sensor 21 provided separately from the above sensor. The line sensor 21 does not detect an output of a non-diffused light corresponding to the conductor element 20. Accordingly, only a part corresponding to a conductor pattern region out of outputs of the strip-shaped line sensor 18 is made effective by utilizing an output of the line sensor 21, so as to detect a conductor pattern.

Description

[Detailed Description of the Invention] [Summary] This relates to a device for detecting the cross-sectional shape of a printed wiring board conductor pattern, etc., and in particular, a cross-sectional shape detection device that detects a concave-like defect on the conductor pattern. Regarding this, in a cross-sectional detection device using a light cutting method and a strip-shaped line sensor, it is possible to accurately and quickly detect cross-sectional shapes even when the base material is a printed wiring board with light diffusing properties. In a cross-sectional shape detection device that irradiates a linear light beam to form a light section line on an object, images it from an oblique direction, and detects the cross-sectional shape from the height of the light section line image, a rectangular first line sensor that detects a portion above a predetermined height in the light section line image; a second line sensor that detects a base level portion in the light section line image; and the first line sensor. and a signal processing circuit that generates an output that is masked by the output of the second line sensor.

[Industrial application field]

The present invention relates to a method for detecting the cross-sectional shape of a conductive pattern on a printed wiring board, and more particularly to a cross-sectional shape detecting device for detecting a concave-like defect on a conductive pattern.

When printed wiring boards are manufactured, they are inspected to check whether the conductive patterns formed on the base material are properly formed. In this case, if the conductor pattern has a depression-like defect as shown in Figure 6, it cannot be detected by detecting the two-dimensional pattern alone. (False) indicates a case where there is a neckdown. Also (C)
2 shows a case in which there is a depression in the center that does not reach the base material part.

Inspection of such printed wiring boards is usually performed by detecting the cross-sectional shape of the conductor using a photosection method, but at this time, the inspection is performed without being hindered by the diffused light from the base material.
It is desired that the cross-sectional shape of a conductor pattern can be detected accurately and at high speed.

[Conventional technology]

FIG. 7 shows a conventional cross-sectional shape detection method for a printed wiring board, and shows an example using a light cutting method and a two-dimensional optical sensor. In the figure, laser light irradiated from the vertical direction is condensed into a line through a cylindrical lens 11, and is irradiated onto a printed wiring board 12. As a result, a light cutting line 14 corresponding to the cross-sectional shape of the conductive pattern 13 is obtained, so that the image is formed through the lens 15 from an oblique direction different from the irradiation direction of the laser beam, and a television camera or the like placed on the image forming plane is Detection is performed by the dimensional sensor 16 to detect the cross-sectional shape.

FIG. 8 explains the process of processing a photosection image when the photosection method and a television camera are used.

In FIG. 8, (a) is the original image on the two-dimensional sensor 16 based on the conductor pattern on the printed wiring board 12,
It has been shown that irradiation with laser light produces optical cutting lines. Extraction of a light section line from an original image is generally performed by assuming that the brightness peak point in the y direction of the original image is the center of the irradiated laser beam. In Figure 8 (
b) shows an image of the optical cutting line extracted in this way. By setting the slice level to a certain height h from the height corresponding to the base material part and performing binarization on this optical section line image, the image is binarized as shown in (C). Get the output signal. By performing such an operation on the entire surface of the printed wiring board and displaying an image according to the binarized signal, a cross-sectional shape detection pattern as shown in (d) is obtained.

If there is a part on the conductor pattern of the printed wiring board where the optical cutting line is lower than the slice level h due to date shunting or the like, that part is detected as a pattern as shown by the circle in FIG. 8(d). This makes it possible to detect depression-like defects in the conductor pattern.

The cross-sectional shape detection method shown in FIGS. 7 and 8 has the advantage of relatively high cross-sectional shape detection accuracy, but on the other hand, because it uses a two-dimensional sensor such as a television camera, the inspection speed is The disadvantage is that it is extremely slow.

On the other hand, instead of the two-dimensional optical sensor, it is conceivable to use a one-dimensional optical sensor (line sensor) that can operate at high speed. FIG. 9 shows a cross-sectional shape detection method using a light cutting method and a rectangular line sensor. In the figure, a laser beam irradiated from a vertical direction is condensed into a line through a cylindrical lens 11 and is irradiated onto a printed circuit board 12 . As a result, the conductor pattern 13
Since the optical cutting line 14 corresponding to the cross-sectional shape of the laser beam is obtained, the image is formed through the lens 15 from an oblique direction different from the irradiation direction of the laser beam, and detected by the rectangular line sensor 18 disposed on the imaging surface 17. to detect the cross-sectional shape.

In the case of FIG. 9, the line sensor 18 is configured to detect the optical cutting line only when it exists above a certain height h from the base material part.

FIG. 10 explains the positional relationship between the light section line image and the strip-shaped line sensor in the configuration of FIG. 9. It is shown that the rectangular line sensors 18 arranged in large numbers are arranged so that the height between the position of the optical cutting line image 19 on the base material and the lower end of the line sensor 18 is h.

As a result, a light-cut line image corresponding to the conductor portion 20 is generated on the rectangular line sensor 18, and detected by its output.

In this case, the position of the strip line sensor 18 needs to be kept constant so that the height h of the base material relative to the image is always constant, but this is based on the height of the base material of the printed wiring board 12. A predetermined positional relationship can be maintained at all times by determining this using other means such as the proximity sensor 18A for detecting the material level and controlling it by feeding it to a line sensor moving mechanism (not shown) that adjusts the position of the line sensor 18. It is configured to hang.

FIG. 11 explains the process of processing a light section image when the light section method and the strip line sensor are used.

In FIG. 11, (a) shows the original image on the imaging plane 17 based on the conductor pattern on the printed wiring board 12, which is generated by laser light irradiation. As described above, the strip-shaped line sensor 18 generates an output signal shown in (false) based on the light-cut line image corresponding to the height h or more from the base material part. This output signal is further binarized by providing a slice level th corresponding to the output level corresponding to the base material portion, thereby obtaining a binarized signal shown in (C). By performing such operations on the entire surface of the printed wiring board and displaying an image according to the binary signal, (d
A cross-sectional shape detection pattern is obtained as shown in FIG. If there is a part on the conductor pattern of the printed wiring board where the optical cutting line is lower than the slice level h due to date shunting or the like, that part is detected as a pattern as shown by the circle in FIG. 11(d). This makes it possible to detect depression-like defects in the conductor pattern.

[Problem that the invention seeks to solve]

The cross-sectional shape detection methods shown in FIGS. 9 to 11 have the advantage of enabling high-speed detection of cross-sectional shapes, but on the other hand, it is difficult to detect conductor patterns due to light diffusion in the base material. There is a problem with becoming.

FIG. 12 explains the diffusion of the imaging light when the optical cutting line is applied to the base material part. In the figure, conductor part 2
Optical cutting line corresponding to 0 @! 19A has been shown to cause no diffusion. On the other hand, the base material is made of a resin plate or the like and is usually semitransparent and has light diffusing properties. Therefore, the light-cut line image 19B corresponding to the base material portion is diffused over a wide range, and a part of it is detected by the line sensor 18 to generate a noise output. This makes it difficult to detect the conductor pattern on the printed wiring board 12.

The present invention aims to solve the problems of the prior art, and provides a cross-section detection device using an optical cutting method and a strip-shaped line sensor, in which a printed wiring board whose base material part has light diffusing properties is used. The purpose of this invention is to enable accurate and high-speed cross-sectional shape detection even in such cases.

[Means for solving problems]

FIG. 1 shows the basic configuration of the present invention, in which a linear light beam is irradiated to form a light section line on an object, and this is imaged from an oblique direction to determine the height of the light section line image. This cross-sectional shape detection device detects a cross-sectional shape from a cross-sectional shape, and includes first and second line sensors (1, 2) and a signal processing circuit (3).

The first line sensor 1 has a rectangular shape and detects a portion above a predetermined height in a light section line image.

The second line sensor 2 detects the base level portion in the optically sectioned line image.

The signal processing circuit 3 generates an output obtained by masking the output of the first line sensor with the output of the second line sensor.

[For production]

FIG. 2 is a diagram explaining the present invention in detail. Of the two-dimensional pattern on the imaging surface 17 based on the reflected light from the printed wiring board 12 caused by laser light irradiation, for the non-diffuse light section line image 19A generated corresponding to the conductor section 20 As described above, the rectangular line sensor 18 is provided at a position h from the height corresponding to the base material portion to detect this. On the other hand, a diffused light section line image 19B corresponding to the base material part is generated, but in order to prevent this, another line sensor 21 is provided at a position corresponding to the base material part at the bottom of the strip-shaped line sensor 18. Detect. That is, line sensor 21
, only the light output due to the light diffusion of the base material portion of the two-dimensional pattern on the imaging plane 17 is detected, and the light output corresponding to the conductor portion 20 that is not diffused is not detected.

Therefore, by using the output of the line sensor 21 and activating only the portion of the output of the strip-shaped line sensor 18 that corresponds to the conductor pattern area, the output of the line sensor 21 can be used without being disturbed by noise caused by light diffusion in the base material. Conductor patterns can be detected.

〔Example〕

FIG. 3 shows the configuration of an embodiment of the present invention.

In the figure, 30 is helium neon (He-Ne) L/
- a laser which generates a laser beam with a wavelength of 632.8 nm. The light generated by the laser 30 is reflected by a mirror 31 and passes through a beam expander 32 to produce an expanded parallel beam. This beam is condensed into a line through a cylindrical lens 33 and irradiated onto a printed wiring board 35 placed on a transparent mounting table 34, thereby creating a light cutting line according to the cross-sectional shape of the conductor pattern. It is formed. The reflected light from the light cutting line passes through the filter 36 and is imaged by the lens 37. At this time, the filter 36 allows only light of the laser wavelength to pass through. The light from the lens 37 is split through a beam splinter 38, and one part is incident on a strip-shaped line sensor 39 arranged on the imaging plane. The strip type line sensor 39 is the same as the line sensor 1 explained in FIG.
8, a light cutting line image which is located at a height h from the image corresponding to the base material portion and which is not diffused from the conductive pattern is detected, and its signal is input to the processing circuit 41.

The other beam split through beam splinter 38 is guided to television camera 42 . The television camera 42 forms a two-dimensional optical sensor and detects the entire optical section line image. The signal from the television camera 42 is input to the microprocessor 43, and the microprocessor 43 calculates the height of the base member from this signal. Information on the calculated height of the base material portion is fed back to the motor driver 44. Motor driver 4
4 drives the moving mechanism 40, thereby moving the moving mechanism 40.
changes the position of the strip-shaped line sensor 39 mounted thereon, and is controlled so that the strip-shaped line sensor 39 is always kept at a constant height h from the image corresponding to the base material portion.

On the other hand, the white light from the white light source 6 passes through a filter 6, where the laser wavelength light is cut off, and is irradiated onto the back side of the mounting table 34 through a light guide 47 made of an optical fiber, thereby illuminating the printed wiring board section from the back side. The resulting image of the conductor pattern at the optical cutting line position passes through a filter 48 and is focused by a lens 49 . At this time, the filter 4B cant the light at the laser wavelength. The line sensor 50 is the lens 4
9, and detects an image of the base material portion.

The signal processing circuit 41 uses the signals from the strip-shaped line sensor 39 and the signal from the line sensor 50 to separate and extract the signal of the optically sectioned line image of the portion corresponding to the conductor pattern area. It goes without saying that the light generated by the laser 30 may be used as a light source for detecting the image of the base material portion.

FIG. 3A shows an example of the characteristics of each filter in the embodiment shown in FIG. 3, where (al is the filter 48
The He-Ne laser wavelength is 632.8 nm.
It has been shown that it has the characteristics of a band cut filter that cuts off light in a narrow band centered on .佽) shows the characteristics of the filter 36, and the He-Ne laser wavelength is 632.
It has been shown that it has the characteristics of a bandpass filter that passes light in a narrow band centered around 8 nm.

FIG. 4 explains the process of separating and extracting optical signals in the signal processing circuit. In the figure, 51 is a binarization circuit that binarizes the signal from the line sensor 50. Reference numeral 52 denotes a gate consisting of an analog switch or the like, which turns on/off the signal from the strip line sensor 39 based on the signal from the binarization circuit 51 and outputs the signal. The edict is a binarization circuit that binarizes the output of the gate 52 to generate an output signal.

When an output is generated from the line sensor 50, the binarization circuit 51 turns off the gate 52 and outputs the output from the strip line sensor 39.
The gate 52 is turned on only when no output is generated from the line sensor 5o, and the signal from the rectangular line sensor okara is allowed to pass through.

Since the binarization circuit 53 binarizes this output signal and generates an output, only the light cutting line image that is not diffused from the conductor pattern is generated based on the diffused light from the base material part, as explained with reference to FIG. Detection is possible without interference from noise.

FIG. 5 explains the process of processing a light section image in the embodiment shown in FIG.

In FIG. 5, (al) shows the original image on the imaging plane based on the conductor pattern on the printed wiring board 35 generated by laser light irradiation, and the conductor portion is shown with diagonal lines. (b) shows an output signal based on the diffused light section line image in the base material part detected by the line sensor 50, and the output level decreases in the conductor part.(C) shows the output signal from the line sensor father. Binarization circuit 5
1 shows an output signal sliced and binarized at a certain level. (dl indicates the output signal from the strip line sensor 39, and in addition to the output signal based on the non-diffused light section line from the conductor part, there is an output signal based on the diffused light section line image from the base material part. (81 indicates the output signal obtained by controlling the gate 52 according to the output signal from the binarization circuit 51, and the output signal from the base material part in the output signal from the strip line sensor 39. It is shown that the part of the output signal based on the diffused light-cut line image of the gate 52 is masked.
The output signal of the binarization circuit 53 is shown in which the output signal of the circuit 53 is binarized, and it is shown that the output is generated corresponding to only the conductor portion. In this case, detection of depressions or the like in the conductor portion can be performed arbitrarily by appropriately selecting the height h for the strip-shaped line sensor 39.

〔Effect of the invention〕

As explained above, according to the present invention, the output of the strip-shaped line sensor that detects the light-cut line image of the conductor portion is masked by the output of another line sensor that detects the light-cut line image of the base material portion. Since the detection output signal is obtained, cross-sectional shape detection can be performed accurately and at high speed even in the case of printed wiring boards etc. where the base material part has light diffusive properties. can be detected.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic configuration of the present invention, FIG. 2 is a diagram explaining the present invention in detail, FIG. 3 is a diagram showing the configuration of an embodiment of the present invention, and FIG. Figure 4 is a diagram illustrating the processing of separating and extracting optical signals in the signal processing circuit, and Figure 5 is a diagram showing the processing of optically cut images in the embodiment of Figure 3. Figure 6 is a diagram explaining the process, Figure 6 is a diagram illustrating defects in conductor patterns, Figure 7 is a diagram showing a conventional method for detecting the cross-sectional shape of a printed wiring board, and Figure 8 is a diagram using an optical cutting method and a television camera. Figure 9 is a diagram illustrating a cross-sectional shape detection method using the optical cutting method and a rectangular line sensor; Figure 10 is a diagram showing the optical cutting line in the composition ratio of Figure 9. A diagram explaining the positional relationship between the image and the strip-shaped line sensor, FIG. 11 is a diagram explaining the process of processing a light-cut image using the light-cutting method and the strip-shaped line sensor, and FIG. 12 shows the light-cutting line. It is a figure explaining the diffusion of. 30... Helium neon (He-Ne) laser 31.
...Mirror n...Beam expander 33...Cylindrical lens 34...Placement stand...Printed wiring board 36, 46.48-...Filter correction, 49...Lens wing...Beams Printer 39... strip line sensor, 40... line sensor moving mechanism 41... signal processing circuit 42... television camera guide... microprocessor 44... motor driver 45... white light source 47 ...Light guide 50...Line sensor 51.53...Binarization circuit 52...Gate

Claims (1)

[Claims] In a cross-sectional shape detection device that irradiates a linear light beam to form a light section line on an object, images it from an oblique direction, and detects the cross-sectional shape from the height of the light section line image. , a rectangular first line sensor (1) that detects a portion of the light section line image that is above a predetermined height, and a second line sensor (2) that detects a base level portion of the light section line image. , a signal processing circuit that generates an output in which the output of the first line sensor is masked by the output of the second line sensor (
3) A cross-sectional shape detection device comprising: