JP2010107250A - Device of inspecting inspection object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device of inspecting an inspection object for obtaining image data for precisely perceiving a three-dimensional shape of the inspection object with a simple structure. <P>SOLUTION: In the appearance inspection device, first to third line sensors perform the scanning of the images of first to third scanning lines 130 to 134, respectively. A pattern illumination source irradiates a surface to be inspected of a board with light from an oblique direction to form an inspection pattern on the surface to be inspected. An analysis unit uses the image data obtained by scanning the board to inspect the height of the surface to be inspected by a phase shift method. In the first to third line sensors and the pattern illumination source, the interval between scanning lines and the period of the inspection pattern are set so that n&times;a=Pv, where n is the number of the first to third scanning lines 130 to 134, a is the interval between the first to third scanning lines 130 to 134, and Pv is the period of the inspection pattern in a sub-scanning direction. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an inspection apparatus for an inspection object, and more particularly to an inspection apparatus for an inspection object that scans an image of a scanning line extending on an inspection surface of the inspection object using a line-shaped sensor array.

For example, an apparatus for inspecting an inspection object using image data obtained by imaging an inspection object such as a substrate is known. However, it is difficult to grasp the shape of the surface to be inspected in the height direction even if an image obtained by viewing the surface to be inspected perpendicularly is captured as it is. For this reason, for example, the slit illumination source that displaces the light projection position of the slit light on the inspection surface by rotational movement projects the slit light from the oblique direction onto the inspection surface of the substrate, and the reflected light directed vertically upward from the inspection surface There has been proposed a scanning head that detects this with a line sensor (see, for example, Patent Document 1).
JP 2004-226318 A

  In the technique described in the above-mentioned patent document, it is necessary to accurately match the displacement speed of the slit light with the movement speed of the substrate. On the other hand, there is a great need for technology for grasping the three-dimensional shape of an object to be inspected such as a substrate, and it is strongly desired to reduce the cost of the apparatus by adopting a simple configuration.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an inspection device inspection apparatus that can acquire image data for accurately grasping the three-dimensional shape of an inspection object with a simple configuration. It is to provide.

  In order to solve the above-described problems, an inspection apparatus for an object to be inspected according to an aspect of the present invention includes an image of each of a plurality of scanning lines extending in parallel with each other on the same plane as the surface to be inspected of the object to be inspected. A plurality of line-shaped sensor arrays scanned by the apparatus, a moving means for relatively moving the plurality of scanning lines and the object to be inspected in the sub-scanning direction, and irradiating light on the surface to be inspected from the oblique direction. And an illumination source for forming a stripe pattern on the surface to be inspected, in which stripes extending linearly at an angle with respect to a plurality of scanning lines are periodically arranged in the direction perpendicular to the extending direction, and a stripe pattern is formed Inspection means for inspecting the height of the inspection surface by a phase shift method using image data obtained by scanning the inspection object. The plurality of line-shaped sensor arrays and the illumination source have n × a = when the number of the plurality of scanning lines is n, the interval between the plurality of scanning lines is a, and the period of the stripe pattern in the sub-scanning direction is Pv. The interval between the scanning lines and the period of the stripe pattern are set so as to be Pv.

  According to this aspect, by forming the inspection pattern fixed in the pattern formation region, the position in the height direction of the object to be inspected can be obtained without forming the inspection pattern fixed to the surface to be inspected. It becomes possible. For this reason, a configuration for accurately matching the displacement speed of the inspection pattern and the moving speed of the inspection object is not necessary, and the three-dimensional shape of the inspection object can be accurately grasped with a simple configuration. Note that the line-shaped sensor array may be a line sensor or a line-shaped sensor array included in the area sensor.

  According to the inspection object inspection apparatus of the present invention, image data for accurately grasping the three-dimensional shape of the inspection object can be acquired with a simple configuration.

  Hereinafter, embodiments of the present invention (hereinafter referred to as “embodiments”) will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows a configuration of an appearance inspection apparatus 10 according to the first embodiment. The appearance inspection apparatus 10 includes a main unit 12 and a test unit 14. Below the test unit 14, a support base 22 is provided on which the substrate 1 as an object to be inspected is gripped. A scanning head 16 and a guide 18 such as a linear guide are provided above the test unit 14. The scanning head 16 moves horizontally when the stepping motor 20 operates. The guide 18 supports the scanning head 16 and guides the scanning head 16 when the scanning head 16 moves.

  The scanning head 16 includes an illumination unit 30, a lens 32, and a line sensor unit 34. These members are fixed on the frame 36. The illumination unit 30 includes a side illumination source, a pattern illumination source, a half mirror, and the like, which will be described later. The reflected light vertically upward from the substrate 1 is guided to the lens 32 by the half mirror, and after passing through the lens 32, is input to the line sensor unit 34 which is a one-dimensional CCD sensor. The line sensor unit 34 images the substrate 1 line by line and outputs the image data 54. The line sensor unit 34 has a plurality of line sensors as will be described later.

  The main unit 12 controls the entire apparatus as a whole. The main unit 12 can be realized by a CPU, memory, or other LSI of any computer in terms of hardware, and an appearance inspection loaded into the memory in terms of software. It is realized by a functional program or the like, but here, functional blocks realized by their cooperation are depicted. Accordingly, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

  The main unit 12 includes a head control unit 40, a memory control unit 42, a memory 44, an analysis unit 46, and a determination criterion storage unit 48. The head control unit 40 controls lighting of the side illumination source and the pattern illumination source by supplying the illumination control clock 50 to the illumination unit 30. In addition, the head control unit 40 controls the movement of the scanning head 16 by supplying a motor control signal 52 to the stepping motor 20. Further, the head control unit 40 controls the start of writing of the image data 54 by the memory control unit 42 by outputting a test start signal 56 to the memory control unit 42.

  The memory control unit 42 controls the writing of the image data 54 to the memory 44. The analysis unit 46 reads the image data for appearance inspection and the image data for height measurement from the memory 44 in parallel with the scanning or after the scanning is completed. Determination criteria are stored in the determination criterion storage unit 48 in advance. The analysis unit 46 analyzes the read image data, and determines whether or not the mounting state of the components on the board 1 is acceptable in light of the determination criterion recorded in the determination criterion storage unit 48 in advance.

  FIG. 2 is a perspective view of the test unit 14 according to the first embodiment, and FIG. 3 is a schematic view of the test unit 14 according to the first embodiment viewed in the main scanning direction. Hereinafter, the configuration of the test unit 14 will be described in detail with reference to both FIG. 2 and FIG.

  The illumination unit 30 includes a side illumination source 102, an acrylic sheet 104, a half mirror 108, and a pattern illumination source 122. A pair of side illumination sources 102 are provided so as to extend in a direction perpendicular to the moving direction of the scanning head 16. The acrylic sheet 104 is disposed below each of the pair of side illumination sources 102.

  The two side illumination sources 102 each have an LED (light emitting diode) group 120, and are inclined so as to efficiently project side light onto the surface of the substrate 1 under inspection. The acrylic sheet 104 has an action of diffusing side light from the side illumination source 102. This is because the side illumination source 102 is an aggregate of LEDs that are point light sources, and if there is no diffusing action, spot-like light may be reflected in the image data and adversely affect inspection accuracy. The half mirror 108 reflects the reflected light directed vertically upward from the surface of the substrate 1 that is the surface to be inspected toward the line sensor unit 34.

  The line sensor unit 34 includes a first line sensor 150, a second line sensor 152, and a third line sensor 154 each formed by a line-shaped sensor array with 5000 to 10,000 image sensors. The first line sensor 150, the second line sensor 152, and the third line sensor 154 are arranged to extend in parallel to the main scanning direction with an interval c. Instead of the line sensor unit 34, an area sensor may be used. In this case, among the images captured by the area sensor, the inspection of the substrate 2 is performed using an image of a portion captured by a line-shaped sensor array that is included in the area sensor and extends in parallel to the main scanning direction at an interval c. To implement.

  The first scanning line 130, the second scanning line 132, and the third scanning line 134 are defined as straight lines that extend in parallel to each other on the same plane as the surface to be inspected of the substrate 1. The first line sensor 150 scans an image of the first scanning line 130 viewed from a direction perpendicular to the surface of the substrate 1. The second line sensor 152 scans an image of the second scanning line 132 viewed from a direction perpendicular to the surface of the substrate 1. The third line sensor 154 scans an image of the third scanning line 134 viewed from a direction perpendicular to the surface of the substrate 1. Hereinafter, the first scanning line 130, the second scanning line 132, and the third scanning line 134 are collectively referred to as a “scanning line group” as necessary. The direction in which these scanning lines face is referred to as “main scanning direction”, and the direction parallel to the surface to be inspected of the substrate 1 and perpendicular to the main scanning direction is referred to as “sub-scanning direction”.

  The head control unit 40 moves the scanning head 16 in the sub-scanning direction by supplying a motor control signal 52 to the stepping motor 20. As a result, the first scanning line 130, the second scanning line 132, and the third scanning line 134 move on the surface to be inspected of the substrate 1 in the sub-scanning direction. Therefore, the guide 18, the stepping motor 20, and the head control unit 40 move the first scanning line 130, the second scanning line 132, and the third scanning line 134 with respect to the substrate 1 during the scanning timing by the line sensor unit 34. It functions as a moving means that moves relative to the substrate 1 by moving in the sub-scanning direction.

  The pattern illumination source 122 includes a light source 124, a pattern filter 126, and a magnifying optical system 128. The pattern filter 126 gives periodic light intensity to the light emitted from the light source 124 so that the projected image forms a stripe pattern. The light source 124 is an LED. Of course, other types of light sources may be used as the light source 124.

  The pattern illumination source 122 irradiates the surface to be inspected of the substrate 1 from an oblique direction so as to form a fixed inspection pattern for the pattern forming region 140 including a part of each scanning line of the scanning line group. . At this time, the pattern illumination source 122 uses, as an inspection pattern, a stripe pattern in which stripes extending linearly at an angle with respect to each scanning line of the scanning line group are periodically arranged in the direction perpendicular to the extending direction. Formed in the pattern formation region 140.

  Here, the fringe pattern formed by the pattern illumination source 122 will be described with reference to FIG. FIG. 4 is a diagram illustrating a relationship between a fringe pattern formed by the pattern illumination source 122 according to the first embodiment and a scanning line group. In FIG. 4, the diagonal line indicates a portion with low illuminance in the stripe pattern.

  The pattern illumination source 122 forms a fringe pattern in the pattern forming region 140 that is constituted by stripes extending linearly at an angle θ with respect to the sub-scanning direction. In the first embodiment, the pattern illumination source 122 forms a stripe pattern having θ of 45 degrees. However, the pattern illumination source 122 may form a fringe pattern with another angle θ that is greater than zero degrees and less than or equal to 90 degrees.

  Hereinafter, the number of scanning lines in the scanning line group is n, and the scanning line interval is a. Also, let Pv be the periodic interval of the fringe pattern in the sub-scanning direction. In the first embodiment, since the number of scanning lines is 3, n = 3. In the first line sensor 150 to the third line sensor 154 and the pattern illumination source 122, the scanning line interval and the inspection pattern periodic interval are set so that n × a = Pv. By setting the scanning line interval and the inspection pattern period interval in this way, the phase shift method is performed using the image data scanned at the same timing by the first line sensor 150 to the third line sensor 154. It becomes possible to inspect the height of the component mounted on the substrate 1 by using it. In addition, when the interval between stripes of the stripe pattern is the pattern interval Pr, Pr = Pv × sin θ. For this reason, the above formula can also be expressed as n × a = Pr / sin θ.

  FIG. 5 is a flowchart showing an inspection procedure of the appearance inspection apparatus 10 according to the first embodiment. The processing in this flowchart starts when a user presses a start button (not shown).

  When the start button is pressed by the user, the head control unit 40 moves the scanning head 16 to the start position (S10). When the scanning head 16 is moved to the start position, the head control unit 40 causes the line sensor unit 34 to scan the scanning line group under uniform illumination with the side illumination source 102 turned on (S12). When the scanning of the scanning line group under uniform illumination is completed, the head control unit 40 turns off the side illumination source 102 and causes the line sensor unit 34 to form a stripe pattern with the pattern illumination source 122 forming a stripe pattern. Is scanned (S14).

  When the scanning by the line sensor unit 34 under both uniform illumination and stripe pattern formation is completed in this way, the head control unit 40 operates the stepping motor 20 to advance the scanning head 16 in the sub-scanning direction by a predetermined interval. (S16). This process of S12-S16 is called one scanning process.

  When one scanning process is completed, the head control unit 40 determines whether or not the scanning head 16 has reached the end position using the length of the substrate 1 input in advance in the sub-scanning direction (S18). When the end position has not been reached (N in S18), the process proceeds to S12, and one scanning process is repeatedly performed until the scanning head 16 reaches the end position.

  By repeatedly performing one scanning step in this manner, the line sensor unit 34 captures an image of the substrate 2 on which a fringe pattern having a shifted phase is projected. Specifically, in the present embodiment, the line sensor unit 34 has three line sensors arranged in parallel at equal intervals. Therefore, the line sensor unit 34 acquires three images in which the phase of the fringe pattern is shifted by 120 degrees by repeatedly executing this one scanning process. By acquiring an image of the object to be inspected on which the fringe pattern whose phase is shifted is thus obtained, the component height can be inspected by the phase shift method.

  When the scanning head 16 has reached the end position (Y in S18), the analysis unit 46 analyzes the image data captured during uniform illumination and illuminates the determination criteria held in the determination criterion storage unit 48, thereby providing a substrate. 1. Comprehensive inspection relating to the presence / absence of misalignment or missing parts of the components mounted in 1 or errors in the mounted components is executed (S20).

  Further, the analysis unit 46 analyzes the image data picked up at the time of forming the stripe pattern, and calculates the height of the component mounted on the substrate 1 using the phase shift method. Since the method for calculating the component height using the phase shift method is known, a description thereof will be omitted. The analysis unit 46 compares the calculated height of each component with a determination criterion relating to the height of the component held in the determination criterion storage unit 48, so that a foreign object is caught between the substrate and the electronic component foot. A height inspection, such as whether it is floating or the solder is sufficiently applied, is also carried out as part of the overall judgment. The appearance inspection apparatus 10 includes a display and a display control unit (not shown) that controls display on the display. When the comprehensive inspection is completed, the display control unit displays the comprehensive inspection result on the display (S22).

(Second Embodiment)
FIG. 6 is a diagram illustrating the relationship between the fringe pattern formed by the pattern illumination source 122 according to the second embodiment and the scanning line group. In FIG. 6, a broken line shows a low illuminance portion in the stripe pattern.

  The pattern illumination source 122 forms a fringe pattern composed of stripes extending at right angles to the sub-scanning direction in the pattern formation region 140. Therefore, θ = 90 degrees in the above formula, and the pattern interval Pr = sub-scanning direction interval Pv. Therefore, in such a stripe pattern, the scanning line interval a and the pattern interval Pr are set so that n × a = Pr.

(Third embodiment)
FIG. 7 is a diagram illustrating an area sensor 200 used in the appearance inspection apparatus according to the third embodiment. In the third embodiment, an area sensor 200 is used instead of the line sensor unit 34. Except for this point, the configuration of the appearance inspection apparatus according to the third embodiment is the same as that of the first embodiment.

  The area sensor 200 has pixels 202 arranged in a grid. The analysis unit 46 is an image obtained by the area sensor 200 capturing an image captured by the pixel row 204 that captures the image of the scanning line separated by the scanning line interval a where n × a = Pv among the pixels 202. Extract from the data. The user can input the position and number of scanning lines to the main unit 12 using an input device such as a mouse or a keyboard. The analysis unit 46 acquires the position and number of the scanning lines input in this way, and specifies the pixel row 204 that captures the image of the scanning line. As described above, even when the area sensor 200 is used, it is possible to simultaneously pick up images of a plurality of scanning lines as in the case of imaging with the line sensor, and the substrate 1 is efficiently inspected using the phase shift method. It becomes possible to do.

  The present invention is not limited to the above-described embodiments, and an appropriate combination of the elements of each embodiment is also effective as an embodiment of the present invention. Various modifications such as design changes can be added to each embodiment based on the knowledge of those skilled in the art, and embodiments to which such modifications are added can also be included in the scope of the present invention. Here are some examples.

  In a modification, instead of moving the scanning head 16 in the sub scanning direction, the support base 22 is moved in the sub scanning direction. This also makes it possible to move the substrate 1 and the scanning line group relatively in the sub-scanning direction.

It is a figure which shows the structure of the external appearance inspection apparatus which concerns on 1st Embodiment. It is a perspective view of the test unit concerning a 1st embodiment. It is the schematic diagram which looked at the test unit which concerns on 1st Embodiment in the main scanning direction. It is a figure which shows the relationship between the fringe pattern formed by the pattern illumination source which concerns on 1st Embodiment, and a scanning line group. It is a flowchart which shows the test | inspection procedure of the external appearance inspection apparatus which concerns on 1st Embodiment. It is a figure which shows the relationship between the fringe pattern formed by the pattern illumination source which concerns on 2nd Embodiment, and a scanning line group. It is a figure which shows the area sensor used with the external appearance inspection apparatus which concerns on 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Board | substrate, 10 Appearance inspection apparatus, 16 Scan head, 30 Illumination unit, 34 Line sensor unit, 40 Head control unit, 42 Memory control unit, 44 Memory, 46 Analysis unit, 48 Judgment reference | standard storage part, 122 Pattern illumination source, 124 Light source, 126 pattern filter, 128 magnifying optical system, 130 first scanning line, 132 second scanning line, 134 third scanning line, 140 pattern formation region, 150 first line sensor, 152 second line sensor, 154 third line Sensor.

Claims (1)

A plurality of line-shaped sensor arrays each scanning a respective image of a plurality of scanning lines extending in parallel with each other on the same plane as the surface to be inspected of the object to be inspected;
Moving means for relatively moving the plurality of scanning lines and the object to be inspected in a sub-scanning direction;
A stripe in which stripes extending linearly with an angle with respect to the plurality of scanning lines are periodically arranged in a direction perpendicular to the extension direction by irradiating light on the inspection surface of the inspection object from an oblique direction An illumination source for forming a pattern on the surface to be inspected;
An inspection means for inspecting the height of the surface to be inspected by the phase shift method using image data obtained by scanning the object to be inspected with the stripe pattern formed thereon,
With
When the number of the plurality of scanning lines is n, the interval between the plurality of scanning lines is a, and the period of the fringe pattern in the sub-scanning direction is Pv. An inspection apparatus for an object to be inspected, wherein an interval between scanning lines and a period of a stripe pattern are set so that n × a = Pv.

Images