JP2002139555A - Scanning type circuit board inspection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scanning type circuit board inspection apparatus capable of either relaxing the requirements for the accuracy of setting a circuit board or a light beam device or the like, or enhancing the accuracy of light-beam scans, for solving the problem of inspection apparatus using electronic scans or those using two-dimensional scans of light beams that the positioning accuracy of a circuit board and, in the case of light-beam scans, scanning accuracy, are so important and that the reliability cannot be insured unless strict settings and measures against vibration are made. SOLUTION: The scanning type circuit board inspection apparatus which can insure the accuracy of light-beam scans, even if a circuit board and a light- beam scanning system may be moved relative to each other by vibration or impact, by always checking a reference position through preliminary scans prior to inspection to adapt the reference position at the control side and to relax the requirements for the accuracy of setting the circuit board and that of setting the light-beam scanning system, and further detecting the positions of light beams in the vicinity of the circuit board to perform closed-loop control, is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection apparatus for a printed circuit board, and more particularly to an inspection apparatus for a circuit board by light beam scanning or electronic scanning which can flexibly cope with a circuit board having a high wiring density.

[0002]

2. Description of the Related Art A printed circuit board on which electronic components are mounted is manufactured using a thin film forming technique such as etching and plating. With higher functionality, the density of mounted components is higher, and the gap between wires is becoming smaller year by year. Pre-inspection of printed circuit boards, which are difficult to correct after mounting due to high density, is becoming increasingly important, but the difficulty is also increasing due to the high density. In the past, in general, a continuity or non-conduction test was performed by accessing each wiring pattern on a printed circuit board in a contact or non-contact manner. However, access points are discretely determined in order to cope with high density. Rather, there have been various technical proposals that enable continuous access using a light beam or an electronic scanning method. For example, an inspection technique that causes an optical change in an electro-optic crystal to perform electronic scanning with an image sensor or two-dimensional scanning with a light beam, or an electrode device having a photoconductive layer facing a circuit board. This is an inspection technique for performing two-dimensional light beam scanning.

However, in these inspection techniques, the position of the electrodes on the circuit board depends on the set position of the circuit board, so that the arrangement and fixation of the circuit board requires high accuracy. Further, in the case of light beam scanning, the scanning accuracy of the light beam is important, and there is a problem that the scanning accuracy cannot be improved unless the setting of the light beam scanning device and measures against vibration are thoroughly implemented.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to reduce the setting accuracy of a circuit board or a light beam device or improve the accuracy of light beam scanning in a scanning type circuit board inspection device. It is an object of the present invention to provide and provide such a scanning circuit board inspection apparatus.

[0005]

According to a first aspect of the present invention, there is provided a scanning type circuit board inspection apparatus having a preliminary scanning process for recognizing a reference position and the like prior to the inspection of a circuit board. Setting accuracy can be reduced.

That is, the potential distribution having the electrode layer and the electro-optic layer is two-dimensionally electronically scanned by the image pickup device.
Alternatively, in the case of performing detection by performing two-dimensional scanning with a light beam, a potential is applied to one or a plurality of electrodes on the circuit board to perform pre-scanning to detect a known electrode position. Then, the correction process is performed in consideration of the relationship between the first position signal and the position of the pixel when the image sensor is used, or the electrode position where the control signal of the light beam scanning means is detected as the first position signal in the case of light beam scanning. By performing the above, it is possible to control the circuit board so that it can be adapted even if the position of the circuit board is not so exact.
Further, by similarly performing the correction processing in association with the distance between the plurality of electrodes with the first position signal, the setting accuracy of the enlargement or reduction ratio by the scanning system can be eased.

A scanning circuit board inspection apparatus according to a second aspect of the present invention includes means for obtaining a second position signal of a light beam indicating a two-dimensional position of a light beam spot near a circuit board. A closed loop control for controlling a minute position of a light beam by a position signal is realized. With this configuration, the light beam can follow the light beam even if the relative position of the light beam scanning system and the circuit board is displaced due to vibration and impact, and the influence on the scanning accuracy of the light beam can be reduced.

More specifically, a group of substantially transparent light receiving elements in a periodic lattice are formed on a transparent substrate, and a second position indicating a two-dimensional position of the light beam is obtained by a signal difference between the light receiving elements adjacent vertically and horizontally. Signal. However, since the second position signal indicating the position of the light beam fluctuates periodically, it is used together with the first position signal, or the position of the light beam is controlled while counting the period of the second position signal fluctuating from the reference position. I do.

The light receiving element group can be independently disposed between the light beam and the liquid crystal layer or between the photoconductive layer and the light beam scanning system. However, for the purpose of the present invention, the light receiving element group is provided on a substrate having the liquid crystal layer or the photoconductive layer. A more accurate system can be configured by fixedly providing them.

According to the scanning type circuit board inspection apparatus described above, the reference position is always confirmed by the preliminary scanning prior to the inspection and is adapted on the control side, so that the setting accuracy of the circuit board, the setting accuracy of the light beam scanning system, etc. Inspection can be performed with good accuracy even if the stress is reduced, and the position of the light beam near the circuit board is detected and closed loop control is performed. Therefore, displacement between the circuit board and the light beam scanning system due to vibration and impact , The light beam scanning accuracy can be ensured.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a scanning circuit board inspection apparatus according to the present invention.

FIG. 1 shows a first embodiment of the present invention, which is an example in which a liquid crystal layer and an image pickup device arranged opposite to a circuit board are used. In FIG. 1, an electrode portion is disposed to face a circuit board 11 fixed to a substrate support portion 12, and a transparent substrate 13 is provided.
A transparent electrode 14, a liquid crystal layer 15, and the like are stacked on top of it.
Electrodes are electrically connected to the electrodes on the circuit board 11 from pins or connectors, and a potential is applied between the electrodes and the transparent electrode layer 14 to cause an optical change in the liquid crystal layer 15. The illumination light 17 illuminates the liquid crystal layer 15 with the illumination light 17 through the transparent substrate 13, the transparent electrode 14, and the like, and the reflected light 1 b is collected by the condenser lens 1 a in the imaging device 18 to form an image on the imaging device 19, and an electric signal is generated. Into the control device.

FIG. 2 shows a correspondence diagram when a circuit pattern on the circuit board 11 is captured as an image. In the figure, when only the circuit patterns 21 and 22 on the circuit board 11 are contacted from the back via pins, and a voltage is applied between the circuit board 11 and the transparent electrode 14 to capture an image by the above-described method, Nos. 23 and 2 as voltage changes of each pixel 25
4 is recognized.

As described above, the potential distribution on the circuit board is converted into an electric signal as the brightness of an image and taken in. The problem always arises when the position on the circuit board and the position in the taken image are changed. Relationship. Of course, inspection is performed after clarifying the relationship between them using a circuit board or the like for position adjustment in advance, but in this case, it is important to fix the circuit board 11 with a predetermined accuracy and to perform circuit inspection. The purpose of the present invention is to accurately maintain the relative position between the substrate supporting unit 12 as a fixing means of the substrate 11 and the imaging device 18. However, when the circuit board 11 is sequentially replaced and inspected, there are variations in the set position of the circuit board 11 or deterioration over time of the substrate support unit 12, and the board inspection apparatus has a considerable amount of moving mechanism and vibration. Because the environment is added, the substrate support 12
The relative positional relationship between the camera and the imaging device 18 is also subject to change. Therefore, no problem arises when the required resolution is low, but a high-density substrate requires frequent position adjustment.

In the present invention, in order to address these problems, the reference position in the image is adapted to the circuit board according to the procedure shown in FIG. That is, a preliminary scan is performed each time the circuit board is set prior to the inspection, and a voltage is applied between the circuit board 11 and the transparent electrode layer 14 so that a predetermined pattern, for example, 21 or 22, is selected. Is retrieved, the corresponding pattern images 23 and 24 are searched in the image, and their pixel numbers are recognized. This pixel number is the first position signal. Since the positions of the patterns 21 and 22 in the circuit board 11 are known in advance, the pixel number corresponding to the reference position on the circuit board 11 is checked, and the first position signal is determined. The prescan is completed by storing the difference between the two.

In the inspection of the circuit board, a test pattern is selected, a voltage is applied between the test pattern and the transparent electrode layer 14, an image is captured, a pixel position of the image pattern is detected, and a pixel position corresponding to a reference position is determined. The position of the pattern image is known by performing the correction process, and the quality of the pattern is determined.

Since the preliminary scanning is performed every time the circuit board is changed as described above, even if the circuit board is shifted within a predetermined range, it is possible to cope with it and the setting accuracy can be relaxed. In addition, a plurality of patterns to be checked in the pre-scanning correspond to the case where there is a defect, and the distance between two points in the circuit board is also made to correspond to the distance between pixels, so that the enlargement / reduction ratio of the optical system in the imaging device 18 can be determined. Correction processing is enabled.

FIGS. 4 and 5 are views for explaining an example in which an image is captured by light beam scanning instead of the imaging device 18 in the first embodiment as a second embodiment of the present invention. FIG. 4 is a schematic diagram of the device. The optical change generated in the liquid crystal layer 15 is detected by the light beam scanning device 41 from the light beam 43.
Is emitted to scan the liquid crystal layer 15, the reflected light 44 is received by the light receiving device 42, and sent to the control device 4e as an electric signal to capture an image. The light beam scanning device 41 is a laser diode 4
7 is converted into parallel light by a shaping lens 48,
After being reflected by the oscillating mirrors 49 and 4a, the light is converged on the liquid crystal layer 15 by the imaging lens 4b. Swing mirror 4
Numerals 9 and 4a slightly change the angle according to an instruction from the control device 4e, and scan the light beam 43 to an arbitrary position on the liquid crystal layer 15. The light receiving device 42 collects the reflected light 44 on the light receiving element 4d by the condenser lens 4c and outputs it as an electric change. Numerals 45 and 46 denote signal lines between the light beam scanning device 41 and the light receiving device 42 and the control device 4e, respectively.

FIG. 5 shows the relationship between the circuit board 11 and the image 51 recognized by the control device 4e. As in the first embodiment, an electric potential is applied between the patterns 21 and 22 and the transparent electrode layer 14 to capture an image by light beam scanning. The positions of the pattern images 52 and 53 recognized by the image 51 are represented by pixel numbers. 2 is different from the case of FIG. 2 in that it is indicated by a voltage for controlling the swing mirrors 49 and 4a. That is, the angle of the two oscillating mirrors 49 and 4a is changed to scan the light beam 43. If the oscillating mirror 49 oscillates the light beam 43 in the horizontal direction and the oscillating mirror 4a oscillates the light beam 43 in the vertical direction, Reference numerals 54 and 57 denote control voltages applied to the oscillating mirrors 49 and 4a, respectively, and correspond to the first position signal of the light beam. Number 55, 5
Reference numeral 8 denotes a voltage, and numbers 56 and 59 indicate horizontal and vertical coordinates, respectively. Therefore, the positions of the pattern images 52 and 53 are recognized as the values of the control voltages 54 and 57. As another means for obtaining the first position signal, a potentiometer for detecting the rotation angle may be arranged on the oscillating mirrors 49, 4a and the output thereof may be defined.

In the second embodiment, there is the same concern as described in the first embodiment, and the procedure shown in FIG. Perform an inspection.
However, the first position signal is replaced with the values of the control voltages 54 and 57.

FIGS. 7 and 8 are diagrams for explaining a third embodiment of the present invention. The electrode section facing the circuit board 11 is formed by laminating a transparent electrode 72 and a photoconductive layer 73 on a transparent substrate 71, and a light beam 7 from a light beam scanning device 74.
5, the photoconductive layer 73 through the transparent substrate 71 and the transparent electrode 72
Is irradiated and scanned to form a local conductive path in the irradiated portion of the photoconductive layer 73, and the signal line 7 connected to the transparent electrode 72 is formed.
7, the electrical resistance or capacitance of a circuit formed by the transparent electrode 72, the photoconductive layer 73, the circuit pattern, and the like is inspected to determine the quality of the pattern on the circuit board 11. Numeral 78 indicates a signal line between the light beam scanning device 74 and the control device 76.
The control device 76 controls the light beam scanning device 74 and inspects the electric resistance between the signal line 77 and the pattern on the circuit board 11. The configuration of the light beam scanning device 74 is the same as that of the light beam scanning device 41 of FIG.

The pattern images in the image 81 recognized according to the third embodiment are exposed on the surface.
There are only 4,85 electrode portions. The positions of these electrodes are also indicated by the values of the control voltages 54 and 57 for the oscillating mirror, as in FIG. 5, and this control voltage is used as the first position signal of the light beam.

In the third embodiment, as in the second embodiment, preliminary scanning is performed prior to inspection, and a reference position is recognized according to FIG. 6 to enable correction processing.

In the third embodiment, it is assumed that one end of a pattern on a circuit board is scanned with a light beam from one side and the other end is connected to a control device via a pin or a connector. It is also possible to form a conductive path and a circuit using only a light beam using a beam. In this case, since the detailed positions of the two light beams and the substrate pattern position are unknown, it is uneconomical to repeat trial and error without limit to form a conductive path for each specific pattern. The pre-scanning procedure can be quickly performed by connecting the specific pattern to the control device with a pin or a connector and executing it. It is more desirable to provide a dedicated reference position confirmation pattern especially on a circuit board.

Although the present invention has been described with reference to the first to third embodiments, it is possible to relax the setting accuracy of the circuit board or the scanning device when inspecting the pattern on the circuit board by electronic scanning or light beam scanning. However, there is a problem of how to make these devices more resistant to vibration, impact, and the like. That is, since a moving mechanism such as transfer and exchange of a circuit board is indispensable, vibration or impact always exists in the apparatus, but scanning of a light beam to an arbitrary point is performed under a predetermined condition even under such conditions. It is necessary to have precision, and this is a problem to be solved when increasing the pattern density on a circuit board. The present invention can realize a scanning circuit board inspection apparatus capable of coping with this point, and a fourth embodiment will be described below.

FIGS. 9, 10 and 11 are views for explaining a fourth embodiment of the present invention. FIG. 9 shows an example in which an electrode portion made of a photoconductive layer is opposed to a circuit board and scanning is performed by a light beam. A light receiving element group for detecting the position of the light beam is arranged in the electrode portion to set a detailed position of the light beam. Is detected and controlled as the second position signal, thereby improving the position accuracy of the light beam and increasing the resistance to vibration or impact. In the figure, the electrode section facing the circuit board 11 is formed by laminating a substantially transparent light receiving element group 92, a transparent electrode 93, a photoconductive layer 94, etc. on a transparent substrate 91. The light beam 96 is transmitted by the light beam scanning device 95 to the transparent substrate 91 and the light receiving element group 9.
2, irradiate and scan the photoconductive layer 94 through the transparent electrode 93 and the like, and form a local conductive path at the position of the photoconductive layer 94 where the light beam is irradiated. The configuration inside the light beam scanning device 95 is the same as that of the light beam scanning device 41 in FIG. Reference numeral 98 denotes a signal line connecting the light receiving element group 92 and the transparent electrode layer 93 to the control device 97, and reference numeral 99 denotes a signal line between the light beam control device 95 and the control device 97.

FIG. 10 shows an example of a planar arrangement structure of the light receiving element group 92. The light receiving elements 101, 102, 103, and 104 have a lattice shape having the diameter of the light beam spot 10a substantially as its period.
104 and the like are arranged. Each light receiving element is constituted by a substantially transparent solar cell, and their outputs are connected so as to output the difference between the outputs of the adjacent light receiving elements vertically and horizontally. For example, in the horizontal direction, the outputs of every other light receiving element from the light receiving element 101 are added to the operational amplifier 106 by the resistor 105 and input to the + input, and the other light receiving elements from the light receiving element 102 are similarly added and added to the negative input. And output 1
At 07, the difference between the outputs of the light receiving elements adjacent in the horizontal direction appears.
Similarly, the output 109 of the operational amplifier 108 is connected so that the output of the adjacent light receiving element in the vertical direction appears. Although the connection to the operational amplifiers 106 and 108 is shown only at the ends, all the light receiving elements are connected as described above.

In such a light receiving element group, the light beam spot 10a is shown in FIG.
The outputs of the light receiving elements 103 and 104 are radiated, and the output of each light receiving element appears in proportion to the area overlapping with the light beam spot 10a. A difference from the sum of the outputs of 102 and 104 appears. Similarly, a difference between the sum of the outputs of the light receiving elements 101 and 102 and the sum of the outputs of the light receiving elements 103 and 104 appears in the output 109 indicating the vertical position. If these outputs are divided by the sum of all outputs of the light receiving elements 101, 102, 103 and 104 and normalized, a stable output can be obtained even with respect to fluctuations in the intensity of the light beam spot.

These outputs 107 and 109 are second position signals indicating the local position of the light beam spot 10a, respectively. The oscillating mirror in the light beam scanning device 95 is controlled so that these outputs become constant values. By driving, the light beam spot 10a can be controlled to an arbitrary position on the liquid crystal layer 94. The outputs 107 and 109 indicating the positions of these light beams are received by the light receiving element group 9 which is in close contact with the circuit board 11 or the liquid crystal layer 94.
2, the light beam 96 is controlled to follow the vibration or impact in the apparatus. The conventional light beam scanning is an open loop control for controlling the rotation angle of the oscillating mirror based on a voltage instructed by the control device. However, the light beam control shown in FIGS. 9 and 10 is a closed loop control. In addition, the scanning accuracy can be improved and the resistance to disturbances such as vibration can be enhanced.

FIG. 11 shows the relationship between the first position signal and the second position signal of the light beam. In the area 111 recognized by the light beam scanning device 95 and the control device 97, the light beam position 112 is displayed in the horizontal and vertical directions by the control voltages 113 and 117 of the oscillating mirror in the same manner as shown in FIG. Is done. The numbers 114 and 118 correspond to the voltages 115 and 11 respectively.
9 indicates horizontal and vertical coordinates, respectively. These control voltages 1
Reference numerals 13 and 117 denote first position signals of the light beam position 112. If the relative position between the light beam scanning device 95 and the circuit board 11 fluctuates due to the presence of vibration or shock, the accuracy is significantly reduced. become. Numerals 11b and 11d indicate outputs 107 and 109, respectively, and indicate a second position signal of the light beam position 112. However, the light receiving element group 10
Since 1, 102, 103, 104, etc. are configured periodically, the second position signal is periodic as shown in FIG. Sharing the first position signal to control the rough position and the detailed position control to the second position signal
Alternatively, it is necessary to perform control while counting peaks and valleys of the second position signal from the reference position. In principle, the light receiving element group for obtaining the second position signal is formed in a lattice shape as shown in FIG. 10, but even if wiring is performed by a pattern on a substrate on which the light receiving element is formed, the connection tends to be too complicated.
The fifth embodiment shown in FIG. 12 is intended to improve this point. FIG. 12 shows a cross section of a light receiving element group formed on an electrode portion facing a circuit board. On a transparent substrate 121, a striped transparent electrode 122, a photoconductive layer 124, a uniform transparent electrode 125, a photoconductive layer 126, and a striped transparent electrode 127 are formed.
Are laminated. Reference numeral 123 denotes a transparent insulating material to be filled between the striped electrodes 122. The striped electrodes 122 and 127 are arranged so as to be substantially orthogonal. In each electrode group, every other electrode is connected so as to obtain a differential output of an adjacent electrode, and a differential output is obtained by an operational amplifier. When the stripe-shaped electrodes 122 are allocated in the horizontal direction and the stripe-shaped electrodes 127 are allocated in the vertical direction, these represent the second position signal of the light beam. The number of constituent layers increases, but the number of wirings can be reduced.

As described with reference to the fourth and fifth embodiments, it has been shown that the scanning of the light beam can be controlled in a closed loop by obtaining the second position signal indicating the position of the light beam near the circuit board. However, in the configuration of the light receiving element group in the fourth and fifth embodiments, the arrangement period is set to be substantially equal to the diameter of the light beam spot, so that there is a slight problem. That is, the second position signal shown in FIG. 11 has periodic peaks and valleys. There is no problem when the light beam spot position 112 is near the zero point like the number 11b indicating the horizontal position, but the number 11d indicating the vertical position
In the case where it is near the deepest part of the valley, there is a problem in accuracy. The output waveform at the valleys and peaks fluctuates due to the relationship between the diameter of the light beam spot and the period of the light-receiving element, and the inclination is difficult to be constant. There is a risk of instability. In consideration of these situations, the light beam diameter and the period of the light receiving element are arranged as the minimum unit gap between the electrodes to be accessed on the circuit board, so that the gap between the light receiving elements is approximately positioned above the electrodes on the circuit board. We can solve it.

The sixth embodiment shown in FIG. 13 shows the structure of a light receiving element which solves the above problem only with the light receiving element configuration and gives more flexibility to the system configuration. The light receiving element groups shown in the fourth and the fifth have a period substantially equal to the light beam spot diameter. However, the same light receiving element group is vertically and horizontally shifted by a half period, and the second position signal of the light beam is arranged. Is to switch and use the output from each light receiving element group according to the position of the light beam spot, and perform scanning control of the light beam. FIG. 13 shows a configuration in which the light receiving element group having the same configuration as the means for obtaining the second position signal formed of the stripe-shaped light receiving element group shown in FIG.

In the figure, reference numeral 131 denotes a transparent substrate, reference numerals 132, 137, 139, and 13d denote transparent striped electrodes, respectively, and reference numerals 134, 136, and 1
3a and 13c indicate photoconductive layers, numbers 135 and 13b indicate uniform transparent electrodes, and numbers 133 and 138 indicate transparent insulating layers, respectively. It is assumed that the striped electrodes 132 and 137 are shifted laterally by a half cycle as shown in the figure, and the striped electrodes 139 and 13d are also shifted by a half cycle in the depth direction. 4 striped electrodes
Although there are layers, the connections in each layer are the same as in FIG. 12, and four outputs are obtained from those light receiving element groups.

FIG. 14 shows four signal waveforms forming the second position signal. In addition to the first position signals 113 and 117 and the second position signals 11b and 11d in FIG. 11, second position signals 141 and 142 obtained from the light receiving element groups newly shifted by a half cycle are indicated by dotted lines. It is.
In the sixth embodiment shown in FIG.
1b, 11d, 141 and 142,
The second position signal of the light beam is used by constantly monitoring the state of these four types of signals and switching according to the position of the light beam.
For example, the second position signal in the horizontal direction is used because the light beam exists on the fixed inclination with the number 11b, and the number 142 is selected as the vertical position signal in the same sense.

A seventh embodiment of the present invention will be described with reference to FIGS. In the fourth, fifth, and sixth embodiments, a light receiving element is arranged near a liquid crystal layer or a photoconductive layer to obtain a second position signal of a light beam, which is fed back to an oscillating mirror to define a fine position of the light beam. The execution of the control has been described.
However, since the configuration of the light receiving element group arranged near the electrode unit is not always simple, the seventh embodiment will be described in which the configuration near the electrode unit is simplified and a load is applied to the light receiving element group at a remote position. .

FIG. 15 shows a schematic configuration of the seventh embodiment. In the figure, an electrode portion opposed to the circuit board 11 is composed of a transparent substrate 151, a reflection control layer 152 for generating a checkered bright and dark pattern in reflected light, a transparent electrode 153, and a photoconductive layer 154. Upon receiving the light beam 156 from the beam scanning device 155, a part thereof is reflected by the reflection control layer 152.
The light receiving device 157 collects the reflected light 158 on the light receiving element array 15a by the condenser lens 159, converts the collected light into an electric signal, and sends the electric signal to the control device 15b via the signal line 15d. The control device 15b outputs a light beam 156 from the obtained image.
Is extracted, and the position of the light beam 156 is finely controlled by controlling the oscillating mirror and the like in the light beam scanning device 155 via the signal line 15e. Numeral 15c indicates a signal line between the transparent electrode layer 153 and the control device 15b.

FIG. 16 shows a specific example of the configuration of the electrode portion facing the circuit board 11 used in the sixth embodiment. In the figure, the electrode section is a transparent electrode 15 on a transparent substrate 151.
3. The photoconductive layer 154 is laminated. Reflection control layer 1
52 is not shown in the figure because it was realized by the shape around the transparent electrode layer 153. The region 161 where the intensity of the reflected light is small and the region 162 where the intensity of the reflected light is small by reflecting a part of the irradiation light are formed in a checkered pattern. The explanation will be expanded as follows. One surface of the transparent substrate 151 is formed in a checkered pattern with a rough surface having gentle irregularities at a period of several micrometers and a flat surface, and a thin translucent layer is formed thereon. . In this embodiment, since the transparent electrode layer 153 also functions as the thin film translucent layer, a conductive metal thin film having a reflectance of about 20% is formed by sputtering or the like.
Further, a photoconductive layer 154 is formed thereon.

In the figure, reference numeral 164 denotes a conductive metal thin film portion in a flat region, and reference numeral 165 denotes a conductive metal thin film portion in a region having irregularities. When the incident light 166 is input to the flat area 164, the reflected light 167 is reflected in a uniform direction according to the incident angle, and when the incident light 166 is input to the uneven area 165, the reflected light 169 is randomly generated according to the slope of the uneven slope. Since the light travels in the direction, the reflected light can be given strength. If the position is set so that the light receiving device 157 does not receive the reflected light 167 from a flat area, the light receiving apparatus 157 receives the reflected light 169 from the uneven area and recognizes the area as bright.
The transmitted lights 168 and 16a travel in substantially the same direction as the incident light 166 and have little effect other than the intensity, provided that the materials forming the upper and lower portions of the conductive metal thin film have the same refractive index. Photoconductive layer 154
If the thickness is small, even if there is some disturbance in the transmitted light, there is little effect, so there is no need to strictly consider the refractive index.
However, in the case where the thickness of the photoconductive layer 154 is increased and the beam diameter of the transmitted light affects the resolution, the surface of the transparent substrate 151 is made flat and has a thin refractive index thereon or the same refractive index as the photoconductive layer. If a material is added, the surface is made uneven by pressing a mold, etc., and if a photoconductive layer is formed after the conductive metal thin film is applied, the refractive index of the upper and lower conductive metal thin films will be the same, so that the transmitted light will be distorted. Will not occur.

FIG. 17 shows an image obtained from the output of the light receiving device 157, and a procedure for obtaining the second position signal of the light beam from the image will be described. The light receiving device 157 receives the reflected light from the electrode portion covering almost the entire circuit board 11, but only the portion having the reflected light intensity of a certain value or more is extracted because the intensity of the portion irradiated with the light beam 156 is large. BA number 1
As shown at 71, an image having a light beam spot shape is obtained. Checkered light and dark patterns 172 and 173 are obtained in the reflected light from the electrode portion irradiated with the light beam 156.
Focusing on a part of the checkered pattern, a second position signal of the light beam is obtained from the positional relationship between the boundary indicated by reference numeral 175 and the center point 174 of the image 171, for example. If the resolution of the light receiving device 157 allows, a code corresponding to the address is recorded in a part of the checkerboard pattern, and if it is recognized, the control accuracy can be further improved.

In the above, examples have been shown in which the position control of the light beam is finely performed using the fourth to seventh embodiments. In these embodiments, examples having only a photoconductive layer have been described. However, it is effective to have a liquid crystal layer. There is considerable freedom in the position of the light receiving element group or the reflection control layer, and the function can be expected if the light receiving element group is arranged on the upper surface of the transparent substrate or in the middle. The method of realizing the reflection control layer in the seventh embodiment can also be configured by using a hologram or other techniques in addition to the above embodiments.

In the first to third embodiments, the correction process is performed by recognizing the correlation between the reference point on the circuit board and the position recognized by the scanning system, that is, the first position signal, having the preliminary scanning. In the fourth to seventh embodiments, it has been explained that the density of the circuit board can be increased by detecting the second position signal which is the fine position of the light beam and controlling the scanning system.
Among them, the relationship between the second position signal and the pre-scan was not described in detail, but it is obvious that the control of the light beam by the second position signal also requires the recognition of the reference position in the pre-scan. It is.

[0041]

As described above, according to the present invention, an arbitrary point on a circuit board is accessed by electronic scanning or light beam scanning to determine the quality of the circuit board. In the inspection equipment, the reference position on the circuit board is adaptively corrected, so the setting accuracy of the circuit board can be relaxed. Also, the light beam position is detected near the circuit board and finely controlled, so that it is not subject to vibration and shock. Since it is strong and can improve accuracy, it is effective for inspection of high-density circuit boards.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment of the present invention.

FIG. 2 is a diagram showing a positional relationship between a two-dimensional image, a pixel, and a circuit board.

FIG. 3 is a flowchart of a board inspection including a pre-scan in the first embodiment.

FIG. 4 is a diagram showing a configuration of a second embodiment of the present invention.

FIG. 5 is a diagram showing a positional relationship between a two-dimensional image, a control voltage, and a circuit board.

FIG. 6 is a flowchart of a board inspection including a pre-scan in the second embodiment.

FIG. 7 is a diagram showing a configuration of a third embodiment of the present invention.

FIG. 8 is a diagram showing a positional relationship between a two-dimensional image, a control voltage, and a circuit board.

FIG. 9 is a diagram showing a configuration of a fourth embodiment of the present invention.

FIG. 10 is a diagram showing a grid-like light receiving element group arrangement and connection.

FIG. 11 is a diagram showing a relationship among a first position signal, a second position signal, a light beam position, and the like.

FIG. 12 is a sectional view showing the arrangement of a striped light receiving element group according to a fifth embodiment of the present invention;

FIG. 13 is a sectional view of two light receiving element groups shifted by a half cycle according to a sixth embodiment of the present invention.

FIG. 14 is a diagram illustrating a signal waveform and a light beam positional relationship of two light receiving element groups shifted by a half cycle.

FIG. 15 is a diagram showing a configuration of a seventh embodiment of the present invention.

FIG. 16 is a structural view of an electrode portion for including a light and dark pattern in reflected light.

FIG. 17 is an image for detecting a second position signal.

[Explanation of symbols]

11 ... circuit board, 12 ...
・ Substrate support, 13 ... Transparent substrate,
14: transparent electrode, 15: liquid crystal layer,
16 light source, 17 illumination light, 18 imaging device 19
... Imaging device, 1a ... Condenser lens, 1b ... Reflected light 21,22 ... Circuit pattern, 23,24 ... Circuit pattern image, 25 ... Pixel 41 ... Light beam scanning device , 42 ...
.Light receiving devices, 43 ... light beams,
44 ... reflected light, 45, 46 ... signal line,
47 ... Laser diode, 48 ...
・ Shaping lens, 49, 4a ・ ・ Swinging mirror, 4b ・ ・ ・ Imaging lens,
4c: condenser lens, 4d: light receiving element,
4e: Control device 51: Image, 52, 5
3 ··· Pattern image, 54, 57 ·· Control voltage,
55, 58... Voltage, 56, 59... Coordinates 71... Transparent substrate, 72.
・ Transparent electrode, 73 ・ ・ ・ Photoconductive layer,
74 ... light beam scanning device, 75 ... light beam, 76 ... control device, 7
7, 78... Signal line 81... Image, 82, 83, 84, 85... Pattern image 91... Transparent substrate, 92.
.Light receiving element group, 93: transparent electrode,
94 photoconductive layer, 95 light beam scanning device, 96 light beam, 97 control device, 98, 99 signal line 101, 102, 103, 104 light receiving element, 105
... Resistance, 106,108
..Op amps, 107,109..Output,
10a: light beam spot 111: area, 112
..Position of light beam, 113,117..Control voltage,
114, 118... Voltage, 115, 119.
-Coordinates, 11b, 11d-Output 121 ... Transparent substrate, 122,
127 striped electrode, 123 ... transparent insulating material, 124, 126 photoconductive layer,
125: Transparent electrode 131: Transparent substrate, 132, 137, 139, 13
d .. Striped electrodes, 134, 136, 13a, 1
3c ··· Photoconductive layer, 133,138 ··· Transparent insulating layer,
135, 13b ··· Transparent electrode 141, 142 ··· Second position signal 151 ··· Transparent substrate, 152 ·
..Reflection control layers, 153, transparent electrodes,
154: photoconductive layer, 155: light beam scanning device, 156: light beam, 157
...... Reception device, 158 ... Reflected light, 159 ... Condenser lens, 1
5a: light receiving element array, 15b: control device,
15c, 15d, 15e... Signal line 161... Large reflected light intensity area, 162.
..Small region of reflected light intensity, 163 ... enlarged view,
164: flat portion, 165:
Irregularities, 166 ... incident light,
167, 169 ... reflected light, 168,
16a: transmitted light 171: image, 172
173 ... light / dark pattern, 174 ... center point,
175 ・ ・ ・ Boundary

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/00 G01R 31/28 L

Claims (10)

[Claims] In a scanning type circuit board inspection apparatus, a predetermined position on an electrode device facing a circuit board is accessed by light beam scanning or scanning on an image to determine whether the circuit board is good or bad. Each time the setting is performed or during the inspection, the pre-scanning is performed to access the electrode device corresponding to the predetermined electrode on the circuit board, and the first position signal of the light beam included in the light beam scanning system or the first position by image scanning. A scanning circuit board inspection apparatus for detecting a relationship with a signal and correcting a position on an electrode device facing the circuit board to secure scanning accuracy. 2. The scanning circuit board inspection apparatus according to claim 1, wherein a plurality of electrodes on the circuit board to be accessed in the pre-scan are provided in addition to the first position signal and the reference position on the circuit. A scanning circuit board inspection apparatus, which also recognizes a relationship with a reference distance and corrects a position on an electrode device facing a circuit board to secure scanning accuracy. 3. The scanning circuit board inspection apparatus according to claim 1, wherein the electrode device is composed of an electrode layer and an electro-optical element. A scanning circuit board inspection apparatus, wherein a predetermined potential difference is given between only a predetermined electrode on a circuit board and detection is performed. 4. The scanning circuit board inspection apparatus according to claim 1, wherein the electrode device is composed of an electrode layer and a photoconductive layer. A scanning circuit board inspection apparatus, wherein a connection is detected by selecting only electrodes on a predetermined circuit board. 5. A scanning circuit board inspection apparatus according to claim 1, wherein when detecting whether or not a circuit pattern between conductive paths formed by a plurality of light beams is good, a predetermined circuit pattern is used. A circuit pattern integrated with the connection point is searched by a light beam to obtain a first position signal. 6. A scanning circuit board inspection apparatus for judging whether a circuit board is good or not by accessing a predetermined position on an electrode device facing the circuit board by light beam scanning and arranged in a path of the light beam. A light receiving element group for outputting a second position signal of the light beam corresponding to the two-dimensional position of the light beam, and controlling the two-dimensional position of the light beam by adding the second position signal of the light beam. Scanning circuit board inspection apparatus characterized by the following: 7. A light receiving element group in a scanning circuit board inspection apparatus according to claim 6, wherein the light receiving element group is formed in a periodic lattice shape substantially equal to the diameter of the irradiation light beam, and each of the lattices corresponds to the amount of received light. Scanning, comprising a light receiving element for outputting an electric signal, and a signal output between the light receiving element vertically and horizontally adjacent to the light receiving element group irradiated with the light beam as a second position signal of the light beam. Type circuit board inspection equipment 8. A light-receiving element group in a scanning circuit board inspection apparatus according to claim 6, wherein the light-receiving element group has a periodic first stripe-shaped light-receiving element group substantially equal to the diameter of the irradiation light beam and a first stripe-shaped light-receiving element group. A second stripe light receiving element group having a different direction from the light receiving element group is laminated, and the output difference between adjacent light receiving elements in the first stripe light receiving element group irradiated with the light beam, A scanning circuit board inspection apparatus, wherein an output difference between adjacent light receiving elements in a striped light receiving element group is used as a second position signal of a light beam. 9. A scanning type circuit board inspection apparatus according to claim 6, wherein the light receiving element group comprises two sets of the light receiving element groups according to claim 7 shifted by a half cycle. Scanning circuit board inspection apparatus characterized in that the second position signal is switched by a position. 10. A scanning type circuit board inspection apparatus for accessing a predetermined position on an electrode device facing a circuit board by light beam scanning to determine whether the circuit board is good or not. It has a reflection control layer that returns reflected light so as to generate a light and dark pattern corresponding to the two-dimensional position of the beam, and a light receiving element array that receives the reflected light. A scanning circuit board inspection apparatus for controlling a two-dimensional position of a light beam by obtaining a second position signal of the beam.