Inspection equipment

Abstract

To provide an inspection device with which it is possible to reduce dead spots of illumination light on the object to be imaged, and improve the accuracy of measurement.SOLUTION: An inspection device 10 comprises: a first imaging unit 21 that images an inspection object 12 from the vertical direction; a plurality of dome-shaped reflection plates 230a-230c that are arranged between the first imaging unit 21 and the inspection object 12, and that have openings 233-236 on the first imaging unit 21 side and the inspection object 12 side, respectively; a plurality of annular light sources 23a-23c that illuminate the respective reflection plates 230a-230c; and apparatuses for inspection (second imaging unit 22, projection unit 24), located on the outside of the reflection plates 230a-230c, that are capable of imaging, or irradiating with light, the inspection object 12. The optical axes of the apparatuses for inspection are arranged so as to pass through open holes 237, 238 that are provided in the reflection plates 230a-230c.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an inspection apparatus.

Background Art

[0002] In an inspection apparatus that images a test object such as a substrate on which electronic components are mounted and inspects the appearance of the test object using the captured image data, as a method of illuminating the test object that is the imaging target, there is a configuration in which a lighting unit having a dome-shaped reflector arranged so as to cover the imaging target from the vertical direction is used, and light from a light source is reflected by the reflector and the imaging target is irradiated with illumination light (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the case of the above-described configuration, in addition to the main imaging unit that images the imaging target from the vertical direction, inspection devices such as an inclined imaging unit that images the imaging target from an oblique direction and a projection unit that projects a pattern stripe onto the imaging target are provided. Therefore, it is necessary to open through holes in the reflector of the lighting unit to pass the optical path. However, when the diameter of this through hole becomes large, a region where the imaging target is not irradiated with illumination light (this region is called a "dead spot") occurs, and there is a problem that the measurement accuracy deteriorates.

[0005] The present invention has been made in view of such problems, and an object thereof is to provide an inspection apparatus capable of reducing dead spots of illumination light on an imaging target and improving measurement accuracy.

Means for Solving the Problems

[0006] To solve the aforementioned problems, the inspection apparatus according to the present invention comprises: a main imaging unit that images an object to be imaged from a vertical direction; a plurality of dome-shaped reflectors positioned between the main imaging unit and the object to be imaged, each having an opening on the main imaging unit side and the object to be imaged side; a plurality of annular light sources that illuminate each of the reflectors; and an inspection device located outside the reflectors that is capable of imaging or illuminating the object to be imaged. Each of the multiple reflectors has an annular projection extending inward at the end facing the object to be imaged, the inner circumference of the projection forms an opening on the object to be imaged side, the light source is positioned on the main imaging side of the projection, the multiple reflectors are connected vertically with their openings touching, and the radius of the opening on the object to be imaged side of the reflector on the main imaging side is the same as the radius of the opening on the main imaging side of the reflector on the object to be imaged side. The optical axis of the inspection device is positioned to pass through a through-hole provided in the reflector. [Effects of the Invention]

[0007] According to the inspection apparatus of the present invention, it is possible to reduce dead spots of illumination light on the object being imaged and improve measurement accuracy. [Brief explanation of the drawing]

[0008] [Figure 1] This is an explanatory diagram illustrating the configuration of the inspection device. [Figure 2] This is an explanatory diagram for illustrating the configuration of the illumination unit, where (a) is a plan view as seen from the first imaging unit side, and (b) is a cross-sectional view of AA in (a). [Figure 3] This is an explanatory diagram showing the arrangement of the illumination unit, the first imaging unit, the second imaging unit, and the projection unit in the imaging unit. [Figure 4] This is an explanatory diagram illustrating the relationship between inspection equipment and through-holes. [Figure 5] This is an explanatory diagram for illustrating the relationship between the projection angle of the illumination unit and the detection of its reflected light, where (a) shows the projection angle of each light source in the illumination unit, and (b) shows an example of the condition of the inspection surface of the object being inspected. [Modes for carrying out the invention]

[0009] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. First, the configuration of the inspection apparatus 10 according to this embodiment will be described using Figure 1. This inspection apparatus 10 is an inspection apparatus that inspects an object to be inspected 12 using image data of an object to be inspected obtained by imaging the object to be inspected 12. The object to be inspected 12 is, for example, an electronic circuit board on which a large number of electronic components are mounted. The inspection apparatus 10 determines whether the mounting state of the electronic components is good or bad based on the image data of the object to be inspected. This inspection is usually performed on multiple inspection items for each component. An inspection item is an item that requires identification of good or bad. Inspection items include, for example, inspection items for component placement such as missing parts, misalignment, and polarity reversal of the component itself, and inspection items for connections between components and the board, such as soldering condition and lifting of component lead pins.

[0010] The inspection device 10 comprises an inspection table 14 for holding the object to be inspected 12, an imaging unit 20 for illuminating and imaging the object to be inspected 12, an XY stage 16 for moving the imaging unit 20 relative to the inspection table 14, and a control unit 30 for controlling the operation of the imaging unit 20 and the XY stage 16. For the sake of explanation, as shown in Figure 1, the surface on which the object to be inspected is placed on the inspection table 14 is defined as the XY plane, and the direction perpendicular to that surface (i.e., the imaging direction by the imaging unit 20 (the imaging axis of the first imaging unit 21 (the optical axis direction of the optical system of the first imaging unit 21))) is defined as the Z direction.

[0011] The imaging unit 20 is mounted on a movable table (not shown) of the XY stage 16 and is movable in both the X and Y directions by the XY stage 16. The XY stage 16 is, for example, a so-called H-shaped XY stage. Therefore, the XY stage 16 includes a Y drive unit that moves the movable table in the Y direction along a Y-direction guide extending in the Y direction, and two X-direction guides and two X drive units that support the Y-direction guide at both ends and are configured to allow the movable table and Y-direction guide to move in the X direction. The XY stage 16 may further include a Z-movement mechanism for moving the imaging unit 20 in the Z direction, or a rotation mechanism for rotating the imaging unit 20. The inspection device 10 may further include an XY stage that allows the inspection table 14 to move, in which case the XY stage 16 that moves the imaging unit 20 may be omitted. Linear motors or ball screws can be used for the X drive unit and Y drive unit.

[0012] The imaging unit 20 includes a first imaging unit 21, which is a main imaging unit that images the object to be imaged, the object to be inspected 12, from a vertical direction; a second imaging unit 22, which is an inclined imaging unit that images the object to be inspected 12 from an oblique direction; an illumination unit 23 that illuminates the object to be inspected 12; and a projection unit 24 that projects a pattern of stripes for three-dimensional measurement onto the object to be inspected 12. In the inspection apparatus 10 according to this embodiment, the first imaging unit 21, the second imaging unit 22, the illumination unit 23, and the projection unit 24 are configured as an integrated imaging unit 20, and in this integrated imaging unit 20, the relative positions of the first imaging unit 21, the second imaging unit 22, the illumination unit 23, and the projection unit 24 are fixed, however each part may be configured to be relatively movable. Alternatively, the first imaging unit 21, the second imaging unit 22, the illumination unit 23, and the projection unit 24 may be separate units and configured to be independently movable.

[0013] The first imaging unit 21 includes an image sensor that generates two-dimensional image data of the object to be imaged, and an optical system (e.g., a lens) for forming an image on the image sensor. The first imaging unit 21 is, for example, a CMOS camera or a CCD camera. The maximum field of view of the first imaging unit 21 may be smaller than the area on the inspection table 14 where the object to be inspected is placed. In this case, the first imaging unit 21 images the entire object to be inspected 12 by dividing it into multiple partial images. The control unit 30 controls the XY stage 16 so that the first imaging unit 21 moves to the next imaging position each time the first imaging unit 21 captures a partial image and outputs partial image data. The control unit 30 combines the partial image data to generate overall image data of the object to be inspected 12.

[0014] The first imaging unit 21 may be equipped with an image sensor that generates a one-dimensional image instead of a two-dimensional image sensor. In this case, the entire image of the object to be inspected 12 can be obtained by scanning the object to be inspected 12 with the first imaging unit 21.

[0015] The illumination unit 23 is configured to project illumination light for imaging by the first imaging unit 21 and the second imaging unit 22 onto the surface of the object under inspection 12. The illumination unit 23 includes one or more light sources that emit light of a wavelength or wavelength range selected from the wavelength range detectable by the image sensors of the first imaging unit 21 and the second imaging unit 22. The illumination light is not limited to visible light, and ultraviolet light, X-rays, etc. may be used. If multiple light sources are provided, each light source is configured to project light of different wavelengths (e.g., red, blue, and green) onto the surface of the object under inspection 12 at different projection angles.

[0016] In the inspection apparatus 10 according to this embodiment, the illumination unit 23 includes a lateral illumination source (in this embodiment, consisting of an upper light source 23a, an intermediate light source 23b, and a lower light source 23c) and a reflector 230 that reflects the light emitted from the lateral illumination sources 23a to 23c and projects illumination light from an oblique direction onto the inspection surface of the object under inspection 12 (i.e., the surface relative to the imaging unit 20 (XY plane)) (details of the lateral illumination sources 23a to 23c and the reflector 230 will be described later). Here, in the inspection apparatus 10 according to this embodiment, the lateral illumination sources 23a, 23b, and 23c are each annular light sources (ring illumination sources) that surround the optical axis of the first imaging unit 21 and are configured to project illumination light obliquely onto the inspection surface of the object under inspection 12 by the reflector 230. Note that each of these lateral illumination sources, the upper light source 23a, the intermediate light source 23b, and the lower light source 23c, may be configured with multiple light sources arranged in a ring. Furthermore, the upper light source 23a, the middle light source 23b, and the lower light source 23c are each configured to project illumination light onto the inspection surface at different angles via the reflector 230.

[0017] Furthermore, each of the lateral illumination sources, the upper light source 23a, the middle light source 23b, and the lower light source 23c, may consist of one ring illumination source or may include multiple ring illumination sources. For example, among the lateral illumination sources, the upper light source 23a may be configured as one ring illumination unit, and the middle light source 23b and the lower light source 23c may be configured as a single integrated ring illumination unit. Alternatively, among the lateral illumination sources, the upper light source 23a and the lower light source 23c may be red illumination sources, and the middle light source 23b may be composed of a green illumination source, a blue illumination source, and a red illumination source. Alternatively, the upper light source 23a and the lower light source 23c may be composed of green or blue illumination sources.

[0018] As described above, in the description of this embodiment, the case of using three types of light sources (side illumination sources 23a to 23c) that irradiate illumination light on the subject 12 from different angles will be described. However, the type (number) of light sources is not limited to three, and two or four or more light sources may be used. For example, in addition to the side illumination sources 23a to 23b, an epi-illumination source that irradiates illumination light on the subject 12 along the optical axis of the first imaging unit 21 may be combined. Alternatively, only some of the side illumination sources 23a to 23c may be used. Also, any one of the light sources 23a to 23c may be used. In that case, it may be configured to acquire a monochrome image using a single-color light source.

[0019] For reference in FIG. 1, among the side illumination sources 23a to 23c, the light beam that is emitted from the upper light source 23a, reflected by the reflector 230, projected onto the subject 12, and further reflected by the inspection surface of the subject 12 and incident on the first imaging unit 21 is indicated by a dashed arrow. Also, among the side illumination sources, the light emitted from the middle light source 23b, the lower light source 23c, and the projection unit 24 and the light incident on the second imaging unit 22 are similarly indicated by dashed arrows. Here, the surface of the subject 12 is illustrated as a plane for convenience of explanation, but in reality, like a general subject, it has inclinations and heights depending on the part.

[0020] Also, the second imaging unit 22 is configured to image the inspection surface (substrate surface) of the subject 12 from an oblique direction. This second imaging unit 22 is also, like the first imaging unit 21, for example, a CMOS camera or a CCD camera. In the illustrated embodiment, the second imaging unit 22 is provided between the middle light source 23b and the lower light source 23c, but the arrangement of the second imaging unit 22 is not limited to this. For example, the second imaging unit 22 may be provided outside the lower light source 23c.

[0021] Note that a plurality of second imaging units 22 may be provided around the first imaging unit 21. The plurality of second imaging units 22 are arranged to image the subject 12 from different directions. By doing so, it is possible to reduce the area that is blocked by the height difference on the inspection surface and not imaged.

[0022] The projection unit 24 projects a pattern onto the inspection surface of the object to be inspected 12. The object to be inspected 12, onto which the pattern has been projected, is imaged by the first imaging unit 21. In the illustrated embodiment, the projection unit 24 is located between the upper light source 23a and the middle light source 23b, but the arrangement of the projection unit 24 is not limited to this, and for example, the projection unit 24 may be located outside the lower light source 23c.

[0023] The inspection device 10 creates a height map of the inspection surface of the object to be inspected 12 based on the pattern image data of the object to be inspected 12, which is captured while the pattern is projected from the projection unit 24. The control unit 30 detects local discrepancies in the pattern image relative to the projected pattern and determines the height of that area based on the local discrepancies. In other words, changes in the imaged pattern (the pattern projected onto the object to be inspected 12 and captured by the first imager 21) relative to the projected pattern (the pattern projected onto the object to be inspected 12 from the projection unit 24) correspond to changes in height on the inspection surface.

[0024] Here, the projection pattern is preferably a one-dimensional stripe pattern in which bright and dark lines alternate periodically. The projection unit 24 is positioned to project the stripe pattern onto the inspection surface of the object to be inspected 12 from an oblique direction. Discontinuities in height on the inspection surface of the object to be inspected 12 are represented as pattern displacements in the stripe pattern image. Therefore, the height difference can be determined from the amount of pattern displacement. In the inspection apparatus 10 according to this embodiment, the control unit 30 creates a height map using the PMP (Phase Measurement Profilometry) method, which uses a stripe pattern whose brightness changes according to a sine curve. In the PMP method, the amount of displacement of the stripe pattern corresponds to the phase difference of the sine curve.

[0025] The projection unit 24 comprises a pattern forming apparatus, a light source for illuminating the pattern forming apparatus, and an optical system for projecting the pattern onto the inspection surface of the object to be inspected 12. The pattern forming apparatus may be a variable patterning apparatus capable of dynamically generating a desired pattern, such as a liquid crystal display, or a fixed patterning apparatus in which a pattern is fixedly formed on a substrate such as a glass plate. If the pattern forming apparatus is a fixed patterning apparatus, it is preferable to make the projection position of the pattern variable by providing a moving mechanism for moving the fixed patterning apparatus or by providing an adjustment mechanism in the optical system for pattern projection. Furthermore, the projection unit 24 may be configured to allow switching between multiple fixed patterning apparatuses having different patterns.

[0026] Multiple projection units 24 may be provided around the first imaging unit 21. The multiple projection units 24 are arranged to project patterns onto the object under inspection 12 from different projection directions. In this way, the area that is shadowed and not projected due to height differences on the inspection surface can be reduced.

[0027] The control unit 30 shown in Figure 1 comprehensively controls the entire device. It is implemented as hardware using the CPU, memory, and other LSIs of any computer, and as software using programs loaded into memory. Here, however, the functional blocks realized through the coordination of these components are depicted. Therefore, it will be understood by those skilled in the art that these functional blocks can be realized in various ways using hardware alone, software alone, or a combination thereof.

[0028] Figure 1 shows an example of the configuration of the control unit 30. The control unit 30 comprises an inspection control unit 31 and a memory unit 35. The inspection control unit 31 comprises a height measuring unit 32, an inspection data processing unit 33, and an inspection unit 34. The inspection device 10 also includes an input unit 36 ​​for receiving input from a user or other device, and an output unit 37 for outputting information related to the inspection. The input unit 36 ​​and the output unit 37 are each connected to the control unit 30. The input unit 36 ​​includes, for example, input means such as a mouse or keyboard for receiving input from a user, and communication means for communicating with other devices. The output unit 37 includes known output means such as a display or printer.

[0029] The inspection control unit 31 is configured to perform various control processes for inspection based on input from the input unit 36 ​​and inspection-related information stored in the memory 35. The inspection-related information includes two-dimensional image data of the object to be inspected 12, a height map of the object to be inspected 12, and substrate inspection data (inspection data). Prior to inspection, the inspection data processing unit 33 creates substrate inspection data using the two-dimensional image data and height map of the object to be inspected 12, which are guaranteed to pass all inspection items. The inspection unit 34 performs the inspection based on the created substrate inspection data and the two-dimensional image data and height map of the object to be inspected 12.

[0030] PCB inspection data is inspection data created for each type of PCB. PCB inspection data is, in essence, a collection of inspection data for each component mounted on that PCB. The inspection data for each component includes the necessary inspection items for that component, the inspection window (the image inspection area) for each inspection item, and the inspection criteria that determine whether each inspection item is good or bad. One or more inspection windows are set for each inspection item. For example, in an inspection item that determines the quality of soldering on a component, typically the same number of inspection windows as the number of soldering areas on that component are set in an arrangement corresponding to the arrangement of the soldering areas. Furthermore, for inspection items that use image data that has undergone predetermined image processing, the details of that image processing are also included in the inspection data.

[0031] The inspection data processing unit 33 sets each item of the inspection data according to the board as part of the board inspection data creation process. For example, the inspection data processing unit 33 automatically sets the position and size of each inspection window for each inspection item to match the component layout of the board. The inspection data processing unit 33 may also accept user input for some items of the inspection data. For example, the inspection data processing unit 33 may accept tuning of inspection criteria by the user. The inspection criteria may be set using height information.

[0032] The inspection control unit 31 performs imaging of the object to be inspected 12 as a preprocessing step for creating substrate inspection data. The object to be inspected 12 used is one that has passed all inspection items. As described above, the imaging process is performed by illuminating the object to be inspected 12 with the illumination unit 23, controlling the relative movement of the imaging unit 20 and the inspection table 14, and sequentially capturing partial images of the object to be inspected 12 with the first imaging unit 21 and the second imaging unit 22 to acquire partial image data. Multiple partial image data are captured so that the entire object to be inspected 12 is covered. The inspection control unit 31 combines these multiple partial image data to generate full-surface substrate image data that includes the entire inspection surface of the object to be inspected 12. The inspection control unit 31 stores the full-surface substrate image data in the memory 35.

[0033] Furthermore, as a preprocessing step for creating a height map, the inspection control unit 31 projects a pattern onto the object under inspection 12 using the projection unit 24 while controlling the relative movement between the imaging unit 20 and the inspection table 14. The first imaging unit 21 divides the pattern image of the object under inspection 12 and sequentially captures the images to obtain the divided image data when the pattern is projected. Preferably, the projected pattern is a striped pattern whose brightness changes according to a sine curve based on the PMP method. The inspection control unit 31 synthesizes the divided image data obtained by imaging to generate pattern image data, which is image data of the entire inspection surface of the object under inspection 12. The inspection control unit 31 stores the pattern image data in the memory 35. Alternatively, pattern image data may be generated for only a part of the inspection surface instead of the entire surface.

[0034] The height measurement unit 32 creates a height map of the entire inspection surface of the object under inspection 12 based on the imaging pattern of the pattern image data. First, the height measurement unit 32 obtains a phase difference map of the inspection surface of the object under inspection 12 by determining the local phase difference between the pattern image data and the reference pattern image data for the entire image. The reference pattern image data is a pattern image projected by the projection unit 24 (i.e., image data generated by a pattern forming device built into the projection unit 24). The height measurement unit 32 creates a height map of the object under inspection 12 based on the reference surface that serves as the reference for height measurement and the phase difference map. The reference surface is, for example, the substrate surface of the electronic circuit board being inspected. The reference surface does not necessarily have to be a plane; it may be a curved surface that reflects deformation such as warping of the substrate. The reference surface may be specified in advance by user input, or it may be determined for each individual substrate by, for example, the substrate surface height measurement method described later.

[0035] Specifically, the height measuring unit 32 determines the phase difference of the stripe pattern between each pixel of the imaging pattern image data and the corresponding pixel of the reference pattern image data. The height measuring unit 32 converts the phase difference into height. The conversion to height is performed using the local stripe width near the pixel in question. This is to interpolate the fact that the stripe width on the imaging pattern image data varies depending on the location. This is because, even if the stripe width of the reference pattern is constant, the stripe width changes linearly from one end to the other of the pattern projection area on the inspection surface because the distance from the projection unit 24 differs depending on the position on the inspection surface. Based on the converted height and the reference surface, the height measuring unit 32 determines the height from the reference surface and creates a height map of the object under inspection 12.

[0036] The inspection control unit 31 may create an object under inspection image data having a height distribution by associating the height information contained in the height map of the object under inspection 12 with each pixel of the two-dimensional image of the object under inspection 12. Alternatively, the inspection control unit 31 may perform a three-dimensional modeling display of the object under inspection 12 based on the object under inspection image data with a height distribution. Alternatively, the inspection control unit 31 may superimpose the height distribution onto the two-dimensional object under inspection image data and display it on the output unit 37. For example, the object under inspection image data may be color-coded according to the height distribution. Note that in the inspection apparatus 10 according to this embodiment, the projection unit 24 and the height measurement processing of the object under inspection 12 by the projection unit 24 do not need to be implemented.

[0037] Next, we will describe the method of illuminating the object to be inspected 12 using the illumination unit 23 of the imaging unit 20 when acquiring image data of the object to be inspected 12 using the first imaging unit 21 and the second imaging unit 22 in the inspection apparatus 10 according to this embodiment.

[0038] As shown in Figures 2 and 3, the illumination unit 23 of the imaging unit 20 has the aforementioned side illumination sources (upper light source 23a, middle light source 23b, and lower light source 23c) and a dome-shaped reflector 230 positioned between the first imaging unit 21 and the object under inspection 12. The reflector 230 has openings 233 and 236 formed on the side of the first imaging unit 21 and the side of the object under inspection 12, respectively.

[0039] To explain in more detail, the reflector 230 is divided into three parts, starting from the first imaging unit 21 side, which are dome-shaped: an upper reflector 230a, a middle reflector 230b, and a lower reflector 230c, which are connected to each other by their openings 234 and 235. In the following explanation, the upper reflector 230a, middle reflector 230b, and lower reflector 230c that make up the reflector 230 will also be referred to as the divided parts.

[0040] The upper reflector 230a has an opening 233 on the side facing the first imaging unit 21, and an annular projection 231a extending inward is formed at the end facing the object under inspection 12, with the inner circumference of this projection 231a forming an opening 234. The inner surface 232a of the upper reflector 230a is a reflective surface that reflects light, and the upper light source 23a is positioned on the side of the projection 231a facing the first imaging unit 21. Therefore, the light emitted from the upper light source 23a illuminates the inner surface 232a of the upper reflector 230a, is further reflected by this inner surface 232a, and is irradiated onto the object under inspection 12 through the opening 234.

[0041] The intermediate reflector 230b has an opening 234 on the first imaging unit 21 side, and an annular projection 231b extending inward is formed at the end on the side of the object under inspection 12, with the inner circumference of this projection 231b forming the opening 235. The inner surface 232b of the intermediate reflector 230b is a reflective surface that reflects light. The surface of the projection 231a of the upper reflector 230a on the side of the object under inspection 12 is also part of the inner surface 232b of the intermediate reflector 230b and is a reflective surface. The intermediate light source 23b is positioned on the side of the projection 231b of the intermediate reflector 230b on the first imaging unit 21 side. Therefore, the light emitted from the intermediate light source 23b illuminates the inner surface 232b of the intermediate reflector 230b, is reflected by this inner surface 232b, and is irradiated onto the object under inspection 12 through the opening 235.

[0042] The lower reflector 230c has an opening 235 on the side facing the first imaging unit 21, and an annular projection 231c extending inward is formed at the end facing the object under inspection 12, with the inner circumference of this projection 231c forming the opening 236. The inner surface 232c of the lower reflector 230c is a reflective surface that reflects light. The surface of the projection 231b of the middle reflector 230b facing the object under inspection 12 is also part of the inner surface 232c of the lower reflector 230c and is a reflective surface. The lower light source 23c is positioned on the side of the projection 231c of the lower reflector 230c facing the first imaging unit 21. Therefore, the light emitted from the lower light source 23c illuminates the inner surface 232c of the lower reflector 230c, is reflected by this inner surface 232c, and is irradiated onto the object under inspection 12 through the opening 236.

[0043] Figure 3 is a diagram illustrating the relationship between the side illumination sources 23a to 23c and the reflector 230 in the illumination unit 23, and the relationship between the illumination unit 23 and the first imaging unit 21, the second imaging unit 22, and the projection unit 24. Therefore, in an actual product, for example, the illumination unit 23 may be manufactured by preparing the upper reflector 230a, the middle reflector 230b, and the lower reflector 230c, and the light source unit on which each of the side illumination sources 23a to 23c is mounted, as separate components and assembling them.

[0044] As described above, in the illumination section 23 of the imaging unit 20 in the inspection apparatus 10 according to this embodiment, the upper reflector 230a, the middle reflector 230b, and the lower reflector 230c are connected vertically with their openings 234 and 235 touching. That is, the opening on the inspected object 12 side of the upper reflector 230a and the opening on the first imaging unit 21 side of the middle reflector 230b are both openings 234, so their radii are the same. Similarly, the opening on the inspected object 12 side of the middle reflector 230b and the opening on the first imaging unit 21 side of the lower reflector 230c are both openings 235, so their radii are the same.

[0045] The upper reflector 230a has through-holes 237 arranged in a ring shape with spacing between them, surrounding the opening 233. On the outside of the upper reflector 230a, projection units 24, which are inspection equipment, are arranged in a ring shape so that their optical axes pass through each of the through-holes 237. Here, we show a case where four through-holes 237 are formed, facing each other in the X and Y directions, i.e., spaced 90° apart, and four projection units 24 are arranged for each through-hole 237. However, the number of pairs of through-holes 237 and projection units 24 is not limited to four. For example, it may be composed of three pairs of through-holes 237 and projection units 24 spaced 120° apart, or it may be composed of five or more pairs of through-holes 237 and projection units 24.

[0046] The intermediate reflector 230b has through-holes 238 arranged in a ring shape with spacing between them, surrounding the upper reflector 230a. Outside the intermediate reflector 230b, the second imaging unit 22, which is an inspection device, is arranged in a ring shape so that its optical axis passes through the through-holes 238. Here, we show a case where four through-holes 238 are formed opposite each other in the X and Y directions, with the upper reflector 230a in between, i.e., spaced 90° apart, and four second imaging units 22 are arranged for each through-hole 238. However, the number of pairs of through-holes 238 and second imaging units 22 is not limited to four. For example, it may be composed of three pairs of through-holes 238 and second imaging units 22 spaced 120° apart, or it may be composed of five or more pairs of through-holes 238 and second imaging units 22.

[0047] Furthermore, through holes may be provided in the lower reflector 230c, and inspection equipment may be arranged so that the optical axis passes through these through holes. In this case, as inspection equipment, in addition to the second imaging unit 22, which is the tilt imaging unit described above, and the projection unit 24, a specific wavelength irradiation unit that irradiates the object to be inspected 12 with illumination light of a specific wavelength may be provided.

[0048] As described above, by providing through holes 237 and 238 in the reflector 230 and arranging the inspection equipment so that the optical axis passes through these through holes 237 and 238, as shown in Figure 3, it is possible to irradiate the object under inspection 12 with patterned fringes or illumination light of a specific wavelength at different angles with respect to the imaging axis of the first imaging unit 21, which is the main imaging unit, or to image the object under inspection 12. Furthermore, the inspection equipment can be configured such that the angle between the imaging axis of the first imaging unit 21, which is the main imaging unit, and the optical axis of the inspection equipment increases as the reflector 230 is closer to the object being imaged (in the order of upper reflector 230a, middle reflector 230b, and lower reflector 230c). When arranging the second imaging unit 22, which is an inclined imaging unit, and the projection unit 24 on the reflector 230 as part of the inspection equipment, it is desirable to position the projection unit 24 closer to the first imaging unit 21, which is the main imaging unit, than to the second imaging unit 22. By bringing the projection angle of the projection unit 24 closer to the optical axis of the first imaging unit 21, which is the main imaging unit, the area of ​​shadow on the object under inspection 12 can be reduced. This is particularly effective when the distance between adjacent pitches is short, such as with chip components.

[0049] Furthermore, it is desirable that the light sources (upper light source 23a, middle light source 23b, and lower light source 23c) provided in the lighting unit 23 be controllable by the control unit 30, allowing for control of the lighting timing and color emission of each light source.

[0050] Furthermore, the light sources (upper light source 23a, middle light source 23b, and lower light source 23c) provided in the illumination unit 23 are ring-shaped light sources (ring illumination sources), but can be configured by dividing them into multiple parts (for example, four divisions). In this configuration, it is desirable that the control unit 30 can control the lighting and extinguishing of each part (divided lighting is possible). With this configuration, by lighting all parts of each of the light sources (upper light source 23a, middle light source 23b, and lower light source 23c), it is possible to illuminate the object under inspection 12 from all directions from 0° to 360°, and by lighting some parts (except for the remaining parts), it is possible to illuminate the object under inspection 12 from a specific direction. In this case, all of the upper light source 23a, middle light source 23b, and lower light source 23c may be configured to be divisibly lit, or one or two of the light sources may be configured to be divisibly lit.

[0051] Thus, the inspection apparatus 10 according to this embodiment reflects the illumination light from the light sources 23a to 23c using the dome-shaped reflector 230 and irradiates the object to be inspected 12. Compared to the conventional configuration in which light from the light source is directly irradiated onto the object to be inspected 12, the inspection equipment (second imaging unit 22 and projection unit 24) mounted at an angle can be brought closer to the object to be inspected 12, which is the object to be imaged. As a result, the resolution of the camera and the height reproducibility due to the refinement of the stripes can be improved, and consequently, the inspection accuracy can be improved.

[0052] Furthermore, by using a dome-shaped reflector 230, there is no need to use a diffuser to diffuse the illumination light from the light sources 23a to 23c, thus reducing the loss of light intensity.

[0053] In Figure 3, the dashed line indicates the optical axis (imaging axis) of the first imaging unit 21, the second imaging unit 22, and the projection unit 24. The dashed line indicates the luminous flux of illumination light emitted from the upper light source 23a, the middle light source 23b, and the lower light source 23c, respectively, and reflected by the upper reflector 230a, the middle reflector 230b, and the lower reflector 230c, respectively, and irradiated onto the object under inspection 12. As is clear from Figure 3, the inner circumferential surfaces 232a to 232c of the upper reflector 230a, the middle reflector 230b, and the lower reflector 230c are reflective surfaces on the side of the protrusions 231a and 231b facing the object under inspection 12. Therefore, there is almost no gap between the luminous flux LFa of the illumination light irradiated onto the object under inspection 12 from the upper reflector 230a and the luminous flux LFb of the illumination light irradiated onto the object under inspection 12 from the middle reflector 230b, and there is also almost no gap between the luminous flux LFb of the illumination light irradiated onto the object under inspection 12 from the middle reflector 230b and the luminous flux LFc of the illumination light irradiated onto the object under inspection 12 from the lower reflector 230c. As a result, areas on the object under inspection 12 that are not illuminated by illumination light (the "dead spots" mentioned above) can be eliminated, and the measurement accuracy of the image data of the object under inspection 12 captured in this state can be improved.

[0054] Furthermore, as described above, the illumination unit 23 of the inspection apparatus 10 according to this embodiment does not directly irradiate the object under inspection 12 with illumination light emitted from light sources 23a to 23c, but rather reflects it with a reflector 230 before irradiating the object under inspection 12. If the object under inspection 12 is imaged while the illumination light from light sources 23a to 23c is directly irradiated onto the object under inspection 12, there will be a large variation in the brightness of the captured image data. However, by reflecting the light with a reflector 230 before irradiating, the variation in brightness in the image data can be suppressed, and the measurement accuracy using this image data can be improved.

[0055] Furthermore, as described above, inspection equipment such as the first imaging unit 21, the second imaging unit 22, and the projection unit 24 are positioned so that their optical axes pass through the openings 233 and through holes 237 and 238 formed in the reflector 230. Since the reflector 230 can have a thin structure, it is possible to reduce the size of these openings 233 and through holes 237 and 238. As a result, the reflective surface on the inner circumferential surface of the reflector 230 can be widened, and the area on the object under inspection 12 that is not illuminated by illumination light (dead spot) can be reduced.

[0056] Furthermore, since the field of view or illumination of the inspection equipment widens as you move away from the equipment, it is desirable to configure the inner circumferential surface of the through-holes 237 and 238 in the reflector 230 to have a tapered shape along the field of view or illumination. For example, as shown in Figure 4(a), the inner circumferential surface of the through-holes 237 and 238 may be tapered so that it is approximately parallel to the optical axis of the inspection equipment 22 and 24, or as shown in Figure 4(b), it may be tapered so that it widens from the inspection equipment 22 and 24 side toward the subject 12 side. By making the through-holes 237 and 238 such tapered shapes, it is possible to reduce the size of the through-holes 237 and 238, and thus reduce the area on the subject 12 that is not illuminated by the illumination light (dead spot).

[0057] Furthermore, the above description has described a case in which the light source of the lighting unit 23 is composed of an upper light source 23a, an intermediate light source 23b, and a lower light source 23c, and each light source is placed on the upper reflector 230a, the intermediate reflector 230b, and the lower reflector 230c, which are the divided parts of the reflector 230. However, the divided parts of the light source and reflector are not limited to three sets, and may be composed of two or four or more sets.

[0058] Finally, a method for processing image data captured using the illumination unit 23 will be described. As described above, in the inspection apparatus 10 according to this embodiment, the light sources constituting the illumination unit 23 (upper light source 23a, middle light source 23b, and lower light source 23c) are positioned at an angle to the optical axis (imaging axis) L of the first imaging unit 21, as shown in Figure 5(a), and are arranged to have different projection angles with respect to the reference plane of the object to be inspected 12 (the inspection surface of the object to be inspected 12, which is substantially parallel to the installation surface of the inspection apparatus 10). Specifically, the projection angles are projected in the order of upper light source 23a, middle light source 23b, and lower light source 23c, so that they approach the horizontal direction.

[0059] Light is emitted from each of the light sources 23a to 23c of the illumination unit 23, reflected by each of the divided sections 230a to 230c of the reflector 230, and projected onto the object under inspection 12. Of the light reflected by the object under inspection 12, the intensity of the light other than that which is reflected by the object under inspection 12 and directly incident on the first imaging unit 21 varies depending on the state of the object being measured. For example, in a configuration where the reflectivity is close to 100%, ideally it will be 0. That is, the angle (inclination) of the inspection surface of the object under inspection 12 with respect to the reference plane, and the intensity of the reflected light from the light source that is reflected from this inspection surface and directly incident on the first imaging unit 21 will be high, while the intensity of the reflected light from the other light sources will be 0. For example, if solder with the cross-section shown in Figure 5(b) is formed on the inspection surface of the object to be inspected 12, the intensity of the reflected light from the illumination light from each light source 23a to 23c of the illumination unit 23, as detected by the image sensor of the first imaging unit 21, changes according to the angle of the surface of the solder with respect to the reference plane.

[0060] Therefore, in the case of Figure 5(a), the intensity of light detected by the first imaging unit 21 is such that the light from the upper light source 23a is stronger on inclined surfaces close to the reference plane, and as the inclination of the inclined surface from the reference plane increases, the intensity of the light detected changes in the order of the middle light source 23b and then the lower light source 23c. Therefore, by determining which light source has the strongest light intensity in the image data captured by the first imaging unit 21, it is possible to estimate the angle of the inclined surface on the object under inspection 12 where that light was reflected.

[0061] The angle of the inclined surface of the object under inspection 12 (for example, the angle of the solder side) estimated from the image data captured by the first imaging unit 21 by illumination from the illumination unit 23 (light sources 23a to 23c and divided sections 230a to 230c of the reflector 230) can be determined by the central angle of the illumination and the illumination range. However, it is also necessary to consider changes in the illumination angle due to the position within the field of view (FOV) of the first imaging unit 21 and the settings of the first imaging unit 21.

[0062] Note that the relationship between each light source 23a to 23c of the illumination unit 23 and the angle of the inclined surface of the object under inspection 12 is just one example and is not limited to this configuration. For example, if there are four or more light sources (four or more sets of light sources and reflector divisions), the illumination range for each light source becomes narrower, and the more light sources there are, the greater the resolution when estimating the angle of the inclined surface of the object under inspection 12 (for example, the angle of the solder side) from the captured image data. Also, if the object under inspection 12 is a highly reflective object such as a metal sphere, it may not be possible to measure in the range of 0° to 90°.

[0063] As described above, the intensity of each pixel in the image data obtained by lighting each of the light sources 23a to 23c of the illumination unit 23 and imaging with the first imaging unit 21 is large when it matches the angle of the inclined surface described above, and close to 0 when it does not match. Similarly, the image data captured by the second imaging unit 22, whose optical axis is positioned at a different angle from the optical axis of the first imaging unit 21, can be estimated to be a range of angles different from the range of angles of the inclined surface that can be estimated from the image data captured by the first imaging unit 21. Therefore, the inspection apparatus 10 according to this embodiment is configured to estimate the angle of the inclined surface of the object under inspection 12 (for example, the angle of the solder) for each pixel based on its intensity from the image data obtained by reflecting the light from each of the light sources 23a to 23c of the illumination unit 23 (divided sections 230a to 230c) onto the object under inspection 12 and imaging with the first imaging unit 21 and the second imaging unit 22.

[0064] Alternatively, the light sources 23a to 23c may be sequentially lit to capture an image of the object under inspection 12 with the first imaging unit 21 and the second imaging unit 22, or the first imaging unit 21 and the second imaging unit 22 may be configured with cameras capable of acquiring color image data, and the light sources 23a to 23c may be lit simultaneously in different colors to capture an image of the object under inspection 12 in a single image. In this case, by acquiring image data of the R (red) component, image data of the G (green) component, and image data of the B (blue) component from a single color image data, image data corresponding to each of the light sources 23a to 23c can be obtained.

[0065] Furthermore, the inspection target for estimating the angle of the inclined surface of the object to be inspected 12 using image data captured by the first imaging unit 21 and the second imaging unit 22 is not limited to the solder surface described above, but can also be applied to the shape of the IC lead tip and the shape of the chip electrode. [Explanation of symbols]

[0066] 10 Inspection equipment 12. Object under examination (object to be imaged) 20. Imaging Unit (Imaging Section) 21. First Imaging Unit (Main Imaging Unit) 22. Second imaging unit (examination equipment, tilted imaging unit) 23 Lighting Department 23a~23c light source 24. Projection Unit (Inspection Equipment) 30 Control Units 230 Reflector 230a~230c split part 233,234,235,236 Openings 237,238 through holes

Claims

1. The main imaging unit captures the object to be imaged from a vertical direction, A plurality of dome-shaped reflectors are positioned between the main imaging unit and the object to be imaged, each having an opening on the main imaging unit side and the object to be imaged side, Multiple annular light sources that illuminate each of the aforementioned reflectors, The device includes an inspection device located outside the reflector that is capable of imaging or illuminating the object to be imaged, Each of the plurality of reflectors has an annular projection extending inward at the end facing the object to be imaged, the inner circumference of the projection forms an opening facing the object to be imaged, and the light source is positioned on the main imaging side of the projection. Multiple reflectors are connected with their openings touching in the vertical direction. The radius of the opening on the object-to-image side of the reflector on the main imaging unit side and the radius of the opening on the main imaging unit side of the reflector on the object-to-image unit side are the same size. The optical axis of the inspection device is positioned to pass through a through-hole provided in the reflector. Inspection device.

2. The multiple light sources can be controlled for each individual light source, including the timing of illumination and the color of the emitted light. The inspection apparatus according to claim 1.

3. The inspection device includes at least one of the following: an inclined imaging unit that images the object to be imaged from an oblique direction; a projection unit capable of projecting pattern fringes for three-dimensional measurement; and a specific wavelength illumination unit that irradiates illumination light of a specific wavelength. The inspection apparatus according to claim 1.

4. The inspection equipment is arranged in a ring shape on the reflector with spacing between them. The inspection apparatus according to claim 1.

5. The inspection equipment is configured such that the angle between the imaging axis of the main imaging unit and the optical axis of the inspection equipment increases as the reflector is positioned closer to the object being imaged. The inspection apparatus according to claim 1.

6. The through hole in the reflector has a tapered shape. The inspection apparatus according to claim 1.

7. The through holes are arranged in a ring shape in the reflector, spaced apart from each other. The inspection apparatus according to claim 1.

8. At least one of the multiple light sources is divided into multiple parts, and each part can be controlled to turn on and off. The inspection apparatus according to claim 1.

Images