JP4577717B2 - Bump inspection apparatus and method - Google Patents

Description

  The present invention relates to a bump inspection apparatus and a bump inspection method for inspecting a bump formed on a substrate, and more specifically, a bump inspection apparatus and a bump for inspecting whether a bump is formed on a substrate with a predetermined accuracy. It relates to the inspection method.

  Conventionally, a bump connection method has been proposed as a method for connecting layers of a multilayer printed wiring board. That is, for example, conical bumps are formed on the substrates, and the substrate on which the bumps are formed and another substrate are pressure-bonded so that the bumps penetrate the substrates and the substrates are connected to each other. When bumps are formed on the substrate in this way, it is necessary to accurately create the bumps with respect to the positions where the bumps are formed and the shape of the bumps. Therefore, it is necessary to inspect the substrate after the bumps are formed.

As a method for inspecting bumps formed on a substrate, there is a method of comparing an image (object image) of a substrate to be inspected with an image (master image) of a sample substrate (for example, see Patent Document 1). . In this method, a substrate having bumps formed on the upper surface is imaged from above to obtain a binary image object image. A master image of a binary image is created in advance from CAD data or the like. Then, by comparing the object image and the master image, a difference between the two is detected, and whether or not the bump is formed with a desired accuracy is determined based on the difference.
JP 2001-102761 A

  Here, since a large number of bumps are usually formed on a single substrate, a plurality of bumps are simultaneously compared and inspected, rather than performing an inspection by individually comparing the bumps one by one. It is preferable. Hereinafter, an inspection process in the case of simultaneously comparing a plurality of bumps will be described with reference to FIG.

  In the inspection process, first, a master image and an object image are prepared. FIG. 12 is a diagram illustrating an example of an image when a plurality of bumps are compared simultaneously. FIG. 12 illustrates a case where a comparative inspection is simultaneously performed on three bumps, ie, first to third bumps. FIG. 12A shows an example of a master image. As the master image, a first bump image 91, a second bump image 92, and a third bump image 93 are created in advance. FIG. 12B shows an example of an object image. The object image includes a first bump image 94, a second bump image 95, and a third bump image 96.

  When the master image and the object image are prepared, the master image and the object image are aligned so that each bump can be compared at an appropriate position. For example, the alignment is performed so that the amount (area) of the difference is minimized for all the bumps to be compared. After the alignment, the master image and the object image are compared, and a different part is detected for each bump. For example, it is determined that a bump in which the area of the different portion is larger than a predetermined reference amount is not created with a desired accuracy (that is, a defect). Therefore, bumps with different areas larger than the reference amount due to misalignment, and bumps with different areas larger than the reference amount because they are not formed in the correct shape are judged to be defective. Is done. FIG. 12C is a diagram in which the master image and the object image are displayed in an overlapping manner. In FIG. 12C, the outline of the master image is indicated by a dotted line and the outline of the object image is indicated by a solid line for the purpose of making the drawing easier to see. In FIG. 12C, a different portion is detected for each of the first to third bumps. Then, it is determined whether or not each bump is defective based on the detected area of the different portion.

  Here, actually, the bump is not a defect as long as the shape is accurately formed even if there is some positional deviation. For example, if the bump has a diameter of 50 μm, a positional deviation of about ± 20 μm is allowed. In the example of FIG. 12, the second bump is misaligned, but the shape is accurately formed. Therefore, it should be determined that the second bump is not a defect. On the other hand, it is often necessary to judge the shape more strictly than the positional deviation, and if the bump itself does not have a predetermined area, it is judged as a defect. In the example of FIG. 12, since the shape of the third bump is not accurately formed, it should be determined as a defect. From the above, it can be said that the permissible range regarding the positional deviation of the bump is wider than the permissible range regarding the shape of the bump. That is, the reference amount should be set large for the positional deviation of the bump, whereas the reference amount should be set small for the bump shape.

  However, in the conventional method, since the inspection is performed with the same reference amount with respect to both the position and the shape, an accurate inspection cannot be performed for either one. That is, if the reference amount is set to be small, the allowable range for the positional deviation is set narrow, so it is determined that the bump (second bump in FIG. 12) that is slightly out of position but not originally defective is defective. Will be. On the other hand, if the reference amount is set to be large, the allowable range for the shape is set wide, so that it is determined that the bump (the third bump in FIG. 12) that is not originally allowed is not a defect. Therefore, the conventional inspection method cannot accurately determine the presence or absence of a defect with respect to the bump position and shape.

  Therefore, an object of the present invention is to provide a bump inspection apparatus and a bump inspection method that can accurately determine the presence or absence of a defect with respect to the position and shape of the bump.

In order to solve the above problems, the present invention adopts the following configuration. That is, the first invention is a bump inspection apparatus for inspecting bumps formed on a substrate. The bump inspection apparatus determines whether or not the shape of the bump is correct with respect to an image representing a bump included in an object image obtained by the imaging unit and the object image obtained by the imaging unit, and among the images representing the bump , A shape detection unit that detects an image having a correct bump shape, and an inspection that sets an area including at least an image detected by the shape detection unit as a non-inspection area and other areas as inspection areas among object image areas By comparing the object image and the master image for the inspection region set by the region setting unit, the master image storage unit that stores the master image serving as the reference for inspection, and the inspection region setting unit, the bumps are formed with a predetermined accuracy. And a comparison inspection unit for inspecting whether or not it is formed.

  In the second invention, the inspection region setting unit may set the region of the image detected by the shape detection unit and the surrounding region as a non-inspection region.

  In the third invention, the bump inspection apparatus may further include an inspection region storage unit that stores data representing a region to be compared by the comparison inspection unit in the master image. At this time, the comparison inspection unit compares the master image and the object image for the region that is the inspection region set by the inspection region setting unit and is represented by the data stored in the inspection region storage unit.

  In the fourth aspect of the invention, the data stored in the inspection area storage unit may represent an area corresponding to a bump to be formed on the substrate. At this time, the master image has an image in which a part is missing from the image of the bump to be formed on the substrate.

The fifth invention is a bump inspection method for inspecting bumps formed on a substrate. In the bump inspection method, an imaging step for imaging a substrate, and an image representing a bump included in an object image obtained by the imaging step, it is determined whether or not the shape of the bump is correct. A shape detection step for detecting an image having a correct bump shape, and a region including at least the image detected in the shape detection step among the regions of the object image is set as a non-inspection region, and the other regions are set as inspection regions. An inspection area setting step and a comparison inspection step for inspecting whether or not the bump is formed with a predetermined accuracy by comparing the object image and the master image for the inspection area set in the inspection area setting step are included. It is.

  According to the first and fifth aspects of the invention, a bump image having a correct shape is detected in advance, and the detected bump image area is set as a non-inspection area. Then, by performing a comparative inspection between the object image and the master image for the inspection region, it is possible to detect a bump having an incorrect shape and a bump having a positional deviation exceeding an allowable amount as a defect. Here, the allowable range related to the shape of the bump is determined in the process of detecting a bump image having a correct shape, and the allowable range related to the positional deviation of the bump is determined in the process of setting the non-inspection area. Therefore, according to the present invention, the permissible ranges relating to the shape and position of the bumps can be set independently and appropriately, so that the presence or absence of defects can be accurately determined with respect to the position and shape of the bumps. Further, according to the present invention, since a conventional method can be applied as a comparison inspection method, it is possible to accurately determine the presence or absence of a defect without using a special comparison inspection algorithm.

  According to the second aspect of the invention, it is possible to widen the allowable range related to the positional deviation. In general, there is often no problem even if the allowable range related to the positional deviation of the bump is large. Therefore, the inspection according to the actual situation can be performed by widening the allowable range related to the positional deviation.

  According to the third aspect of the present invention, it is possible to freely set the region to be subjected to the comparative inspection by setting the region to be subjected to the comparative inspection for the master image.

  According to the fourth aspect, when the object image cannot be accurately acquired due to the reflection of the substrate at the time of imaging, the result of the comparative inspection becomes a defect. Therefore, even when only the region of the bump (ideal bump) to be formed on the substrate is the target of the comparative inspection, an accurate inspection result can be obtained for the object image that could not be acquired accurately. Furthermore, since it is only necessary to perform the comparative inspection only on the ideal bump region, the processing amount of the comparative inspection can be reduced.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of a bump inspection apparatus according to the first embodiment of the present invention. The bump inspection apparatus includes a stage 1, a CCD (Charged Coupled Device) camera 2, and an image processing apparatus 3. The bump inspection apparatus 1 is for inspecting whether or not bumps are correctly formed on the substrate S.

  In FIG. 1, a stage 1 places a substrate S to be inspected on its upper surface. For example, conical bumps are formed on the substrate S. The bumps formed on the substrate S are generally about 100 to 50 μm in diameter and about 100 μm in height. The CCD camera 2 is an example of an imaging unit that images the substrate S, and images the substrate S placed on the stage 1 from above. The captured image data (digital data) is used for a comparison inspection process to be described later. In this embodiment, an image obtained by the CCD camera 2 is called an object image, and data representing the object image is called object image data. If the entire surface of the substrate S cannot be imaged at once, the entire surface of the substrate S may be imaged by moving the CCD camera 2 and / or the stage 1 to change the imaging position. The CCD camera 2 outputs the captured object image data of the substrate S to the image processing device 3. The image processing apparatus 3 uses the object image output from the CCD camera 2 to inspect whether or not the bump is correctly formed on the substrate S (whether or not the bump is formed with a predetermined accuracy). Output the result.

  As shown in FIG. 1, the image processing apparatus 3 includes a binarization processing unit 31, an object image storage unit 32, a shape detection unit 33, a bump position storage unit 34, an inspection area setting unit 35, a comparison inspection unit 36, and a master image. A storage unit 37 and an inspection area image storage unit 38 are provided. The image processing apparatus 3 is typically constituted by a personal computer, and processing in the image processing apparatus is performed by executing a predetermined program stored in the image processing apparatus 3. Note that part or all of the processing in the image processing apparatus may be performed by a dedicated processing circuit.

  The binarization processing unit 31 performs binarization processing on the object image data output from the CCD camera 2. That is, the binarization processing unit 31 converts the object image into a binary image in which each pixel is expressed in binary. In the converted object image data, the position where the bump exists is expressed as “1”, and the position where the bump does not exist is expressed as “0”. The object image storage unit 32 stores object image data obtained after conversion by the binarization processing unit 31. The bump position storage unit 34 stores data (bump position data) indicating the position of each bump to be formed on the substrate S. The bump position data is created in advance by an inspector, for example, and stored in the bump position storage unit 34. The bump position data may be any data as long as the position of each bump can be specified. For example, coordinate data representing the center position of each bump or image data may be used. . For example, master image data described later may be used as bump position data.

  The shape detection unit 33 detects a bump image having a correct bump shape among the bump images (images representing the bumps) included in the object image. In the present embodiment, since the bump has a conical shape, a correctly formed bump is represented as a circular area in the object image. That is, in the present embodiment, the shape detection unit 33 detects an image having a circular outer shape among the bump images. The shape detection unit 33 outputs data indicating the detected bump image region (region on the object image) to the inspection region setting unit 35. Note that the area of the bump image that is not in the correct shape is not notified to the inspection area setting unit 35.

  The inspection area setting unit 35 sets an inspection area to be subjected to comparative inspection and a non-inspection area not to be subjected to comparative inspection for the object image. Specifically, the inspection area setting unit 35 generates an image indicating the inspection area and the non-inspection area by performing a process (diffusion process) of diffusing the area of the bump image having the correct shape. More specifically, the inspection area setting unit 35 generates image data representing an image in which a non-inspection area is an area obtained by expanding a correct-shaped bump image area by a predetermined range. In the present embodiment, this image is referred to as a second inspection area image, and image data representing the second inspection area image is referred to as second inspection area image data. The second inspection area image data is data in which each pixel is expressed in binary, like the object image data. For example, in the second inspection area image, the non-inspection area is represented by “0” and the inspection area is represented by “1”.

  On the other hand, the master image storage unit 37 stores master image data. The master image data is data representing an image (master image) of a substrate serving as a reference in the comparison inspection process. A master image is an image of a substrate on which bumps are ideally formed. The master image data may be image data obtained by imaging a non-defective product, or may be image data created from CAD data. The master image data is data in which each pixel is expressed in binary, like the object image data. In the master image data, as in the object image data, the position where the bump exists is represented by “1”, and the position where the bump does not exist is represented by “0”. The inspection area image storage unit 38 stores image data representing the first inspection area image (first inspection area image data). The first inspection area image data is image data that designates an area to be subjected to comparative inspection among areas in the master image. Similar to the second inspection area image data, the first inspection area image data is data in which each pixel is expressed in binary, the non-inspection area is expressed as “0”, and the inspection area is expressed as “1”.

  The comparison inspection unit 36 performs a comparison inspection process on the substrate S using the object image and the master image. That is, the comparison inspection unit 36 performs pattern matching between the object image and the master image, and detects a difference between the bump images included in the object image and the master image. Based on the detected difference, the comparison inspection unit 36 determines whether each bump is formed on the substrate with a predetermined accuracy. For example, when the number of differences in the bump image is smaller than a predetermined number, it is determined that the bump is formed on the substrate with a predetermined accuracy. It is determined that it is not formed on the substrate with accuracy.

  In the present embodiment, the comparison inspection unit 36 does not simply use the object image and the master image, but masks each image (object image and master image) using the first and second inspection region images. A comparative inspection process is performed. Specifically, the inspection area of the master image is defined by the first inspection area image, and the inspection area of the object image is defined by the second inspection area image. That is, the master image is subjected to the comparison inspection only in the region that is the inspection region in the first inspection region image. In addition, as for the object image, only the region that is the inspection region in the first inspection region image is the target of the comparison inspection process. As a result, the region to be subjected to the comparative inspection process is only the region that is the inspection region in both the first inspection region image and the second inspection region image.

  The operation of the bump inspection apparatus according to this embodiment will be described below. In the following description, an example of inspecting whether or not four bumps, that is, first to fourth bumps are formed on a substrate will be described. FIG. 2 is a diagram showing an example of a correctly formed substrate. As shown in FIG. 2, the 1st-4th bumps 41-44 are formed in the board | substrate produced correctly.

  FIG. 3 is a flowchart showing the flow of processing in the image processing apparatus 3 of the bump inspection apparatus. Prior to the processing shown in FIG. 3, the CCD camera 2 captures an image of the substrate S placed on the stage 1. First, in step S1, an object image is acquired. Specifically, object image data obtained by imaging the substrate S placed on the stage 1 is acquired from the CCD camera 2 to the binarization processing unit 31. The object image data acquired by the binarization processing unit 31 is converted into image data in which each pixel is expressed in binary. The converted object image data is stored in the object image storage unit 32.

  FIG. 4 is a diagram showing the object image obtained in step S1. The object image shown in FIG. 4 includes a bump image 46 representing the first bump, a bump image 47 representing the second bump, a bump image 48 representing the third bump, and a bump image 49 representing the fourth bump. From the object image of FIG. 4, on the substrate S, the first bump is formed almost normally, the second bump is formed in a slightly shifted position, the third bump is formed in a chipped shape, It can be seen that the four bumps were formed with correct shapes, although the shapes were correct. In the present embodiment, the first bump and the second bump are determined to be normal, and the third bump and the fourth bump are determined to be defective. That is, a slightly displaced position such as the second bump is allowed, and an improperly shaped shape such as the third bump or a greatly displaced position such as the fourth bump is determined as a defect.

  In the subsequent step S2, a bump having a correct shape is detected among the bumps formed on the substrate S using the object image. Specifically, the shape detection unit 33 determines whether or not each bump image included in the object image has a correct shape (here, a circle). The determination process by the shape detection unit 33 is performed as follows, for example. That is, first, based on the bump position data stored in the bump position storage unit 34, the position where each bump is to be formed (ideal position where the bump is formed) is specified. Next, it is determined whether or not the shape of the bump image existing at the specified position is circular. The determination of whether or not the shape is circular is performed by calculating the diameter of the bump image area in a plurality of predetermined directions and determining whether or not each value of the calculated diameter is within a predetermined range. That is, when each calculated value of the diameter is within a predetermined range, it is determined to be circular, and when each calculated value of the diameter is not within the predetermined range, it is determined not to be circular. It is preferable that the inspector can freely set the value indicating the predetermined range. By changing this value, the inspector can change the allowable amount related to the shape of the bump. The determination of whether or not the shape is a circle is made for each of the regions including the position indicated by the bump position data. In the example of FIG. 4, the determination is performed for each bump image representing the first to fourth bumps. In addition, the shape detection unit 33 passes data representing the bump image determined to have the correct shape to the inspection region setting unit 35. This data may take any form, but in the present embodiment, it is assumed to be image data. Specifically, the image data includes only bump images determined to have a correct shape among the bump images included in the object image data.

  In step S3, a mask is created in which the area of the bump image detected in step S2 is a non-inspection area. Specifically, the inspection area setting unit 35 first specifies the position of the center of each bump image included in the image data received from the shape detection unit 33. Next, an image representing a mask having a circular area centered on the specified position as a non-inspection area and another area as an inspection area is created.

In subsequent step S4, the second inspection region image is created by diffusing the non-inspection region of the image created in step S3. That is, the inspection area setting unit 35 increases the diameter of the non-inspection area of the image data created in step S3 by a predetermined length. As a result, the second inspection area image is created.
Note that the diffusion amount (the predetermined length) for diffusing the non-inspection region is determined in advance. This diffusion amount serves as an index representing an allowable amount related to the positional deviation of the bump. Therefore, it is preferable that the value of the diffusion amount can be changed by the inspector. FIG. 5 is a diagram illustrating a second inspection region image. FIG. 5 shows a second inspection region image obtained from the object image shown in FIG. In FIG. 5, the shaded area is the inspection area. Note that the dotted line in FIG. 5 indicates the area of the bump image determined to have the correct shape, that is, the non-inspection area set in step S3. As shown in FIG. 5, when the object image shown in FIG. 3 is obtained, the area of the bump image representing the first bump, the second bump, and the fourth bump and the surrounding area are non-inspection areas.

  In step S5, a comparison inspection between the object image and the master image is performed. In step S5, the object image data stored in the object image storage unit 32, the second inspection region image data generated by the inspection region setting unit 35, and the master image stored in the master image storage unit 37 are processed. This is performed using the data and the first inspection area image data stored in the inspection area image storage unit 38. FIG. 6 is a diagram showing a master image used in the present embodiment. FIG. 7 is a diagram showing a first inspection region image used in the present embodiment. As shown in FIG. 6, in this embodiment, a bump image representing each bump (ideal bump) when correctly formed is used as a master image. Further, as shown in FIG. 7, the first inspection area image data in the present embodiment is image data having the entire surface as the inspection area. Hereinafter, details of the process of the comparison inspection unit 36 in step S5 will be described.

  The comparison inspection unit 36 first determines a region for performing a comparison inspection on the object image and the master image. Specifically, the region to be subjected to the comparative inspection in the object image is defined by the second inspection region image. That is, among the object images, the region that is the inspection region in the second inspection region image is the target of the comparative inspection. 4 and FIG. 5 as an example, the area of the bump image representing the first, second, and fourth bumps shown in FIG. 4 and the surrounding area are not subjected to comparative inspection. On the other hand, the area to be subjected to the comparison inspection in the master image is defined by the first inspection area image. In the present embodiment, since the entire surface of the first inspection region image is the inspection region (see FIG. 7), the entire surface of the master image is the target of the comparative inspection.

When the region to be subjected to the comparative inspection is determined, the comparative inspection unit 36 performs processing for aligning the position of the bump image in the inspection region with respect to the object image and the master image. In the alignment process, for example, the position is determined so that the amount of difference (area, that is, the number of pixels) between the object image and the master image is minimized in the entire region to be subjected to the comparison inspection. The difference is a pixel having a different value (0 or 1) between the object image and the master image. After the alignment process, the comparison inspection unit 36 performs a comparison inspection between the object image and the master image. It should be noted that the comparative inspection is not performed for the region that is the target of the comparative inspection for only one of the object image and the master image. That is, the comparative inspection unit 36 performs a comparative inspection on an area that is an inspection area in both the first inspection area image and the second inspection area image. FIG. 8 is a diagram for explaining a region where a comparative inspection is performed. In FIG. 8, the bump image included in the object image and the bump image included in the master image are described in an overlapping manner. In FIG. 8, the area other than the area inside the dotted line is the target of the comparison inspection. Therefore, when the object image shown in FIG. 4 is obtained, the comparison inspection is not performed on the bump image 46 and the bump image 51. Further, the comparison inspection is not performed for the bump image 47 and the bump image 52. In addition, regarding the bump image 49 and the bump image 54, although the bump image 49 exists in the non-inspection area, a part of the bump image 54 exists outside the non-inspection area. Is called.

  In the comparative inspection, the comparative inspection unit 36 outputs an inspection result for each bump image representing one bump. Specifically, if a difference between the object image and the master image is detected for each bump and the number of differences is less than a predetermined number, the bump is determined to be normal, and the predetermined number If it is above, it is determined that the bump is defective. Referring to FIG. 8 as an example, a test result relating to the third bump is obtained by performing a comparative test on the bump images 48 and 53. Here, the bump image 48 has a shape in which a part of the circular shape is missing, and the number of differences increases as compared with a case where the bump image 48 is missing. Therefore, the inspection result for the third bump is assumed to be “defect”. In other words, the predetermined number is set to a value such that a bump image that is determined not to have a correct shape by the shape detection unit 33 is determined as a defect.

  Further, in FIG. 8, the areas of the bump image 54 outside the dotted line are all determined to be different. Accordingly, since the number of differences is considered to exceed the predetermined number, the inspection result for the fourth bump is “defect”. As described above, when the position of the bump image included in the master image exceeds the range of the non-inspection area in the second inspection area image, the bump corresponding to the bump image is determined as a defect. Therefore, the permissible amount regarding the positional deviation of the bump is determined by the range of the non-inspection area of the second inspection area image, that is, the amount of diffusion. For example, if the diffusion amount is set to be large, the range of the non-inspection area in the second inspection area image becomes large, so that the allowable amount regarding the positional deviation of the bumps becomes large. On the contrary, if the diffusion amount is set small, the range of the non-inspection area in the second inspection area image becomes small, so that the allowable amount related to the positional deviation of the bumps becomes small.

  The specific method of the comparison inspection in step S5 may be a method based on the difference between the object image and the master image, and a conventional comparison inspection algorithm can be applied.

  In addition, the comparison inspection unit determines that a bump that has not been subjected to the comparison inspection is “normal”. In FIG. 8, since the first and second bumps are not subjected to the comparative inspection, the inspection result for the first and second bumps is “normal”.

  In the present embodiment, it is assumed that the result of the comparative inspection is displayed as an image on a display device (not shown). For example, the comparison inspection unit 36 may display an image obtained by superimposing the object image and the master image on the display device. At this time, if the color is changed between the bump determined to be normal and the bump determined to be defective, the normal bump and the defective bump can be displayed separately. Also, only the inspection area of the second inspection area image may be displayed among the images obtained by superimposing the object image and the master image. At this time, normal bumps are not displayed because they are present in the non-inspection area, and only defective bumps are displayed. This also makes it possible to distinguish between normal bumps and defective bumps. The method for presenting the result of the comparison inspection may be any method as long as it is a method for presenting normal or defect to each worker for each bump. For this, a method of displaying as an image as described above is preferable.

  As described above, according to the present embodiment, the bump inspection apparatus first performs a process of identifying the shape of the bump (step S2). By this process, bumps that are determined to be normal with respect to the shape (for example, the first and second bumps) are detected. After that, the bump inspection device performs a comparison inspection between the object image and the master image (step S5), and detects a bump that is not formed in a correct shape and a bump that is formed with an unacceptable position. Is done. As described above, the determination regarding the shape of the bump and the determination regarding the position are performed separately, whereby the determination threshold regarding the shape and the determination threshold regarding the position can be made different. Specifically, the allowable value related to the shape of the bump can be changed by changing the value indicating the predetermined range in step S2. Further, by changing the value of the predetermined length in step S4, the allowable value related to the bump position can be changed. According to the present embodiment, the threshold values can be appropriately set with respect to the shape and position, so that the presence or absence of a defect can be accurately determined with respect to the position and shape of the bump.

(Second Embodiment)
A bump inspection apparatus according to the second embodiment of the present invention will be described below. The second embodiment is the same as the first embodiment except that the contents of the first inspection region image and the master image are different from those of the first embodiment. That is, the basic configuration (FIG. 1) and operation (FIG. 3) of the bump inspection apparatus are the same as in the first embodiment. In the following description, it is assumed that the position and shape of the sample substrate (FIG. 2) and the acquired object image (FIG. 4) are the same as those in the first embodiment.

  FIG. 9 is a diagram illustrating a first inspection region image used in the second embodiment. As shown in FIG. 9, in the second embodiment, only the region where the bump is to be formed (ideal region where the bump is formed) is set as the inspection region. Therefore, the comparison inspection process can be minimized, the processing load on the image processing apparatus 3 can be reduced, and the process can be performed in a short time.

  Here, in the first embodiment, the bump image included in the master image represents an ideal bump itself. That is, the master image in the first embodiment represents the same area as the inspection area shown in FIG. Here, if the same master image as that of the first embodiment is used in the second embodiment, there is a possibility that the inspection of the bumps cannot be performed accurately. Details will be described below with reference to FIG.

  FIG. 10 is a diagram for explaining virtual comparison inspection in the case where an object image cannot be captured well. When the substrate S is imaged by the CCD camera 2, the bump pattern may not be successfully imaged due to reflection of a copper pattern or the like formed on the substrate S. In this case, specifically, the entire object image data is “1 (means that bumps are formed)” (FIG. 10A). Such an object image should be determined to be defective in the comparative inspection.

  However, when such an object image is subjected to a comparative inspection using the above-described first inspection area image and master image, a defect cannot be detected. That is, if the process of step S2 is performed on the object image whose entire surface is “1”, a correct-shaped bump image is not detected, and therefore the entire surface is the inspection region in the second inspection region image (FIG. 10B). ). On the other hand, the first inspection area image has an ideal area where bumps are formed as the inspection area (FIG. 10E), and therefore, the area to be subjected to the comparison inspection process is the entire area of the first inspection area image. It becomes an inspection area. Here, since the entire surface of the object image is “1”, the value of each pixel of the object image is “1” for the inspection region of the first inspection region image. In the master image, the values of the pixels of the object image are all “1” for the inspection region of the first inspection region image (FIG. 10D). Therefore, regarding the inspection area of the first inspection area image, there is no difference between the object image and the master image (FIG. 10C), and as a result, each bump is determined to be normal.

  Therefore, in the second embodiment, an image obtained by deleting a part of a bump image representing an ideal bump is used as a master image. FIG. 11 is a diagram illustrating a master image used in the second embodiment. As shown in FIG. 11, in the master image in the second embodiment, the central portion of the bump image representing an ideal bump is missing. Note that the shape and size of the missing portion may be any. However, it is necessary to set a missing portion so that a defect image can be determined as a defect if a bump image representing an ideal bump is compared with a master image in which a part of the bump image is missing. In other words, it is necessary to set a missing portion so that a difference between the bump image representing an ideal bump and the master image causes a difference in the result of the comparison inspection.

  As described above, by setting the missing part in the master image, if a comparison inspection is performed for the object image as shown in FIG. 10A, there is a difference between the object image and the master image for the central part. Arise. As a result, each bump is determined to be defective in the comparison inspection process. Therefore, in the second embodiment, by setting a missing portion in the master image, it is possible to correctly determine the defect even when the object image cannot be correctly captured due to reflection or the like.

  In the second embodiment, a properly formed bump is not subjected to comparative inspection because a bump image representing the bump and its surrounding area are non-inspection areas in the second inspection area image. As a result, since the bump is determined to be normal, there is no problem even if a missing portion is set in the master image.

  The present invention can be used for the purpose of accurately determining the presence or absence of defects with respect to the position and shape of bumps formed on a substrate.

The block diagram which shows the structure of the bump test | inspection apparatus which concerns on 1st Embodiment. Figure showing an example of a correctly formed substrate The flowchart which shows the flow of a process in the image processing apparatus 3 of a bump inspection apparatus. The figure which shows the object image obtained by step S1 The figure which shows a 2nd test | inspection area | region image The figure which shows the master image used in this embodiment The figure which shows the 1st test | inspection area | region image used in this embodiment. The figure for demonstrating the area | region where a comparison inspection is performed The figure which shows the 1st test | inspection area | region image used in 2nd Embodiment. The figure for demonstrating the virtual comparative inspection when an object image cannot be imaged well The figure which shows the master image used in 2nd Embodiment. The figure which shows the example of the image in the case of comparing a plurality of bumps simultaneously

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stage 2 CCD camera 3 Image processing apparatus 31 Binary processing part 32 Object image storage part 33 Shape detection part 34 Bump position storage part 35 Inspection area setting part 36 Comparison inspection part 37 Master image storage part 38 Inspection area image storage part 41 ~ 44 Bump 46 ~ 47, 51 ~ 54 Bump image

Claims (5)

A bump inspection apparatus for inspecting bumps formed on a substrate,
An imaging unit for imaging the substrate;
A shape for determining whether or not the shape of the bump is correct for an image representing a bump included in the object image obtained by the imaging unit, and detecting an image having a correct bump shape among the images representing the bump A detection unit;
An inspection area setting unit that sets an area including at least the image detected by the shape detection unit as a non-inspection area and other areas as inspection areas among the area of the object image;
A master image storage unit for storing a master image serving as an inspection reference;
A bump inspection comprising: a comparison inspection unit that inspects whether or not a bump is formed with a predetermined accuracy by comparing the object image and the master image for the inspection region set by the inspection region setting unit. apparatus.   The bump inspection apparatus according to claim 1, wherein the inspection region setting unit sets an image region detected by the shape detection unit and a region around the image region as a non-inspection region. An inspection region storage unit that stores data representing a region to be compared by the comparison inspection unit in the master image;
The comparison inspection unit compares the master image and the object image for an area that is an inspection area set by the inspection area setting unit and represented by data stored in the inspection area storage unit. The bump inspection apparatus according to Item 1. The data stored in the inspection area storage unit represents an area corresponding to a bump to be formed on the substrate,
The bump inspection apparatus according to claim 3, wherein the master image has an image in which a part of the image of the bump to be formed on the substrate is missing. A bump inspection method for inspecting a bump formed on a substrate,
An imaging step of imaging the substrate;
A shape for determining whether or not the shape of the bump is correct with respect to the image representing the bump included in the object image obtained by the imaging step, and detecting an image having the correct bump shape from the image representing the bump A detection step;
An inspection area setting step of setting an area including at least the image detected in the shape detection step as a non-inspection area and another area as an inspection area among the object image areas;
A bump inspection including a comparison inspection step of inspecting whether or not the bump is formed with a predetermined accuracy by comparing the object image and the master image with respect to the inspection region set in the inspection region setting step. Method.

Images