JP5307617B2 - Board mounting state inspection method and board mounting state inspection apparatus - Google Patents

Description

  The present invention relates to a method for inspecting a mounting state between a substrate and an electronic component, and an inspection apparatus therefor.

  Currently, the liquid crystal drive substrate used in various electronic devices such as mobile phones is a COG (Chip On Glass) IC chip or flexible substrate for driving liquid crystal on a transparent substrate constituting the liquid crystal drive substrate. The mounted one is widely used. In this COG mounting, a panel electrode formed on the surface of a transparent substrate and a bump called a bump provided on an electrode of an electronic component such as an IC chip via an anisotropic conductive material such as ACF (Anisotropic Conductive Film). By heating and pressurizing such a convex terminal, the panel electrode of the transparent substrate and the bump of the IC chip are electrically joined via the conductive particles contained in the anisotropic conductive material.

  At this time, whether or not the electronic component is satisfactorily mounted on the transparent substrate can be inspected by observing the overlapping portion of the panel electrode and the bump from the back side of the transparent substrate. That is, when the bump of the IC chip is pressed against the panel electrode of the transparent substrate through the anisotropic conductive material, the conductive particles of the anisotropic conductive material are pressed against the panel electrode. A minute convex portion is formed as an indentation on the surface in contact with the transparent substrate. Therefore, this indentation is detected by observing the back surface of the electrode with a differential interference microscope. As a conventional method for inspecting the mounting state of a substrate, a panel electrode of a transparent substrate mounted with COG is imaged from the back side of the substrate through a differential interference microscope, and light and dark portions of conductive particle indentations are obtained from the obtained binary image data. By emphasizing the boundary by differential processing, the number of conductive particles, that is, the number of conductive particles, is counted, and an electrode whose number of conductive particles is less than a reference value is determined as a poor connection (for example, Patent Documents) 1).

JP 2005-227217 A

However, some transparent substrates to be COG-mounted have depressions formed on the panel electrodes during manufacture. This indentation appears darker than the panel electrode in the image taken with the differential interference microscope, but there may be no difference from the brightness of the dark part of the indentation due to the conductive particles. In some cases, the boundary between the panel electrode and the depression is also emphasized in the same manner as the boundary between the dark portion and the dark portion.
For this reason, in the conventional inspection method, indentations formed on the panel electrode and indentations due to conductive particles cannot be distinguished from each other in the electronic image data captured through the differential interference microscope, and a predetermined number in the panel electrode. Only the following conductive particles are present, that is, even though the connection should be determined to be poor, by determining the depression of the panel electrode as conductive particles, there are more conductive particles than the original number of particles. There is a problem that the defective product is determined as a non-defective product.

  The present invention has been made to solve the above-described problems, and can identify indentations caused by conductive particles and depressions formed in an electrode pattern. The panel electrode provided on a transparent substrate and the above-described Provided are a substrate mounting state inspection method and a substrate mounting state inspection apparatus capable of accurately inspecting a connection state with a bump provided on an electronic component mounted on a transparent substrate.

  The present invention is a mounting state inspection method for a substrate in which an electronic component is mounted on an electrode pattern provided on a transparent substrate via an anisotropic conductive material containing conductive particles, the electrode pattern and the electronic component The overlapping portion with the electrode provided on the transparent substrate is imaged from the back side of the transparent substrate through a differential interference optical system, and the electronic image data of the overlapping portion is acquired, and from the electronic image data, the electrode Extracting a dark pixel group having a luminance lower than the luminance of the pattern image and obtaining the position of the center of gravity of the dark pixel group, and using the center of gravity of the dark pixel group as a base point, within a predetermined distance with respect to a specific direction A step C for searching for a high-brightness pixel having the highest luminance from the pixels existing in the pixel and acquiring the position and luminance of the high-brightness pixel; Less than A plurality of search lines having an angle are set, and a search is made for a low-brightness pixel having the lowest brightness from pixels existing on the plurality of search lines within a predetermined distance from the high-brightness pixel. Step D for obtaining the brightness of a plurality of low brightness pixels, Step E for obtaining the sum of the differences between the brightness of the high brightness pixels and the brightness of the plurality of low brightness pixels, and the sum of the brightness differences and a set value. Step F for discriminating the type of the dark pixel group by comparison.

Further, the present invention is a mounting state inspection method for a substrate in which an electronic component is mounted on an electrode pattern provided on a transparent substrate via an anisotropic conductive material containing conductive particles, the electrode pattern and the From the back side of the transparent substrate, the overlapping portion with the electrode provided in the electronic component is imaged through a differential interference optical system, and the step P for obtaining the electronic image data of the overlapping portion, from the electronic image data, Extracting a dark pixel group having a lower luminance than the luminance of the image of the electrode pattern, obtaining a position and luminance of the center of gravity of the dark pixel group, and a specific direction and the specific using the center of gravity of the dark pixel group as a base point A plurality of search lines having an angle of ± 90 degrees or less with respect to the opposite direction of the direction are set, and brightness is selected from pixels existing on the plurality of search lines within a predetermined distance from the center of gravity. A step R for searching for a plurality of high-brightness pixels for each of the plurality of search lines to obtain positions and luminances of the plurality of high-luminance pixels; a position and luminance of the center of gravity of the dark pixel group; Step S for obtaining the luminance change rate in the plurality of search line directions based on the position and luminance of the luminance pixel, Step T for obtaining the maximum luminance change rate from among the luminance change rates, and other than the specific direction Step U for obtaining the maximum luminance change rate among the luminance change rates in the search line direction set in the direction, and the difference between the luminance change rate obtained in Step S and the luminance change rate obtained in Step U Step V to be obtained and Step W for discriminating the type of the dark pixel group by comparing the difference in luminance change rate with a set value.

  According to this invention, since the indentation caused by the conductive particles and the depression formed in the electrode pattern can be identified, the electrode pattern provided on the transparent substrate and the electronic component mounted on the transparent substrate are provided. It is possible to accurately inspect the connection state with the bump.

It is a side view which shows the structure of the inspection apparatus in Embodiment 1 of this invention. It is sectional drawing (a) of the mounting substrate which is a test subject in Embodiment 1 of this invention, and the enlarged view (b) of a broken-line part. It is the schematic of the image data in Embodiment 1 of this invention. It is a flowchart which shows the test | inspection process in Embodiment 1 of this invention. It is process drawing which shows the inspection process in Embodiment 1 of this invention. It is a flowchart which shows the test | inspection process in Embodiment 2 of this invention. It is process drawing which shows the inspection process in Embodiment 2 of this invention.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, a substrate mounting state inspection apparatus 10 according to the present embodiment controls a mounting stage 1 that is movable in the X and Y axis directions and is rotatable in the θ axis direction, and the above-described axes. And a control device (not shown). A mounting substrate 2 that is an object to be inspected is mounted on the upper surface of the mounting stage 1, and the mounting substrate 2 is fixed on the mounting stage 1 by suction or the like. Above the mounting substrate 2 mounted on the mounting stage 1, a camera 3 as an imaging unit is provided via a differential interference optical system 4, and the camera 3 is fixed toward the mounting substrate 2. . The differential interference optical system 4 is equipped with a lens (not shown) and an illumination device (not shown). The camera 3 and the differential interference optical system 4 are fixed to a stage (not shown) that moves in the Z-axis direction. The camera 3 is connected to an image processing device 5 serving as an image processing unit, and takes an image captured by the camera 3 and performs data processing.

As shown in FIG. 2A, the mounting substrate 2 that is an object to be inspected is formed of an anisotropic conductive material made of ACF on an electrode pattern 21 formed in plural on the surface of a transparent substrate 21 made of glass at intervals. 7, the electrode pattern 21 of the transparent substrate 2 and the bump 61 of the IC chip 6 are bonded to each other by crimping a minute convex terminal called a bump 61 provided on the electrode of the IC chip 6 that is an electronic component. It is an electrical connection. As shown in FIG. 2B, the anisotropic conductive material 7 is a material in which a large number of conductive particles 71 are dispersed in a thermosetting resin film 72. The particles 71 come into contact with the electrode patterns 21 and the bumps 61 to achieve conductivity in the film thickness direction. However, resin is interposed between the conductive particles 71 in the film surface direction to maintain insulation.
In addition, as shown in FIG. 2B, the electrode pattern 21 is formed with a recess 22 that is a manufacturing defect on the side in contact with the transparent substrate 20 when the electrode pattern 21 is manufactured.

  FIG. 3 is an example of image data obtained by imaging the periphery of the crimped portion between the electrode pattern 21 and the bump 61 from the back side of the transparent substrate 20 using the substrate mounting state inspection apparatus 10. FIG. 3 shows an image of the displayed image, and the color tone is different from the actual image.

  In FIG. 3, 21 a is an electronic image of the electrode pattern 21, and 71 a is an image of an indentation formed on the transparent substrate 20 by pressing the conductive particles 71 in the anisotropic conductive material 7 against the electrode pattern 21 ( Hereinafter, it is referred to as “conductive particle image”. Further, 22a is an image of the recess 22 formed in the electrode pattern 21, and a broken line indicates an overlapping region between the bump 61 of the IC chip 6 and the electrode pattern 21.

  In the image data 100, the electrode pattern image 21a is displayed thinner (higher brightness) than the region where the electrode pattern 21 does not exist. Then, the image 71a of the conductive particles 71 existing on the electrode pattern 21 is displayed in a substantially circular shape, and is displayed from a region 71a1 displayed thinner (higher brightness) than the electrode pattern image 21a, and from the electrode pattern image 21a. And a region 71a2 that is displayed darker (low brightness). Moreover, the hollow image 22a of the electrode pattern 21 is displayed in an elliptical shape, a circular shape, or the like, and the whole is darker (lower in luminance) than the electrode pattern image 21a.

  Next, with reference to FIG. 4 and FIG. 5, a mounting state inspection method for a substrate in the present embodiment will be described. 4 is a flowchart of the mounting state inspection method in the present embodiment. FIG. 5A shows a case where the conductive particles 71 are present on the electrode pattern 21, and FIG. It is process drawing which shows the process of the mounting state inspection method in case the hollow 22 exists.

  In the substrate mounting state inspection method in the present embodiment, first, the periphery of the overlapping portion of the electrode pattern 21 and the bump 61 provided on the electronic component 6 is differentiated by the camera 3 provided on the substrate mounting state inspection device 10. An image is taken from the back side of the transparent substrate 21 through the interference optical system 4, and the electronic image data 100 around the crimped portion between the electrode pattern 21 and the bump 61 is acquired (layer imaging process: step A).

  Then, the image data 100 acquired in step A is binarized by using the predetermined gradation K as a threshold value by the image processing apparatus 5 provided in the substrate mounting state inspection apparatus 10 to obtain a bright pixel and a dark pixel. To separate. Then, the center of gravity β of the dark pixel group which is an aggregate of dark pixels is obtained (dark part extraction process: step B). The gradation K, which is a threshold value, is set to a value between the luminance of the electrode pattern image 21a and the luminance of the hollow image 22a of the electrode pattern.

  Next, in the electronic image data 100 obtained in step A, the predetermined specific direction M, that is, the contrast strength of the differential interference optical system 4 is determined based on the center of gravity β of the dark pixel group obtained in step B. A search is made for a high-luminance pixel α having the highest luminance within a predetermined distance in the generated direction M. Then, the position and brightness of the high brightness pixel α are acquired (high brightness pixel search process: step C). The specific direction M is determined by the setting state of the differential interference optical system 4 of the substrate mounting state inspection apparatus 10.

  Then, centering on the high-luminance pixel α obtained in step C, the specific direction (the direction in which the contrast of the differential interference optical system 4 is generated) M and the specific direction M are ± 45 degrees and ± 90 degrees. A total of five search lines are set in a direction having an angle, and the pixel with the lowest luminance on each search line is within a predetermined distance from the high-luminance pixel α and is present on the search line. The luminance pixel γi (i = 1 to 5) is searched. Then, the brightness of the low brightness pixel γi is acquired (dark pixel search process: step D).

  Next, a difference (α−γi) between the luminance of the high luminance pixel α obtained in step C and the luminance of the low luminance pixel γi obtained in step D is obtained, and the sum Σ of these luminance differences is provided in the image processing apparatus. It is obtained by the calculating means (luminance difference integration processing: step E).

  Then, the sum of luminance differences Σ obtained in step E is compared with a predetermined threshold value J (determination process: step F). Here, in the case of the conductive particle image 71a shown in FIG. 5A, since the bright portion 71a1 brighter than the electrode pattern image 21a exists in the direction M in which the contrast intensity of the differential interference optical system 4 is generated, the luminance difference The sum D becomes a large value. On the other hand, in the case of the recessed image 22a of the electrode pattern portion shown in FIG. 5B, only the low-luminance electrode pattern image 21a exists in the direction M in which the contrast intensity of the differential interference optical system 4 occurs. The difference sum Σ is a small value. For this reason, by setting the threshold value J to an appropriate value, when the sum Σ of luminance differences is larger than the threshold value J, it is determined that the dark pixel group extracted in step B is the conductive particle image 71a. In the following cases, it can be determined that the dark pixel group is the hollow image 22a of the electrode pattern.

  As described above, according to the present embodiment, since the conductive particle image 71a and the electrode pattern depression image 22a can be discriminated from each other, it is poorly connected to the electrode pattern 21 in which only a predetermined number or less of the conductive particles 71 exist. Can be determined.

  Note that the predetermined distance for searching for the high-luminance pixel α and the low-luminance pixel in Step C and Step D is a distance determined based on the size of the dark pixel group extracted in Step B, for example, an equivalent ellipse. Is set to the major axis, the perimeter length, or the number of pixels in the dark pixel group, etc., to avoid being affected by other conductive particles 71 and the recesses 22 of the electrode pattern. . In step C of the present embodiment, the number of search lines is five. However, the number and direction of the search lines may be appropriately changed according to the shape of the conductive particle image 71a and the electrode pattern depression image 22a. . However, the search line desirably has an angle of less than ± 90 degrees with respect to the specific direction M, with the position of the high luminance pixel α as the center.

  In the above embodiment, it is determined whether the dark pixel group extracted in step (B) is the conductive particle image 71a or the recessed image 22a of the electrode pattern. In some cases, foreign matter is caught between the substrate 21 and the IC chip 6. In this case, since the sum Σ of the luminance difference is large as in the case of the conductive particle image 71a, the electronic image of the foreign matter can be distinguished from the hollow image 22a of the electrode pattern. Note that the foreign matter and the electrode pattern can be identified using a known mounting state inspection method.

  As described above, according to the present embodiment, the overlapping portion between the electrode pattern and the electrode provided on the electronic component is imaged from the back side of the transparent substrate through the differential interference optical system, and the electronic image data of the overlapping portion is obtained. Acquiring step A, extracting from the electronic image data a dark pixel group having a luminance lower than that of the image of the electrode pattern, obtaining a position of the center of gravity of the dark pixel group, and the dark pixel group Searching for a high-brightness pixel having the highest luminance from pixels existing within a predetermined distance with respect to the center of gravity as a base point, and acquiring the position and luminance of the high-brightness pixel; A plurality of search lines having an angle of ± 90 degrees or less with respect to the specific direction centered on the pixel are set, and pixels existing on the plurality of search lines within a predetermined distance from the high luminance pixel During ~ Step D for searching the low luminance pixels having the lowest luminance to obtain the luminance of the plurality of low luminance pixels, and the sum of the differences between the luminance of the high luminance pixels and the luminance of the plurality of low luminance pixels. Step E is obtained, and Step F for discriminating the type of the dark pixel group by comparing the sum of the luminance differences with the set value. Therefore, the indentation due to the conductive particles and the depression of the electrode pattern are provided. As a result, it is possible to accurately inspect the connection state between the electrode pattern provided on the transparent substrate and the electronic component mounted on the transparent substrate.

  Further, according to the present embodiment, the specific direction M is the direction in which the intensity contrast of the observation image by the differential interference optical system 4 changes, so that the particles and the pattern dents can be easily identified.

  Furthermore, according to the present embodiment, since the predetermined distance is determined based on the size of the dark pixel group, it can be identified as a particle without depending on the size of the depression.

Embodiment 2. FIG.
With reference to FIG. 6 and FIG. 7, the mounting state inspection method of the board | substrate in Embodiment 2 of this invention is demonstrated. Note that the substrate mounting state inspection apparatus according to the second embodiment has the same configuration as that of the first embodiment, and a description thereof will be omitted.
6 is a flowchart of the mounting state inspection method. FIG. 7A shows a case where the conductive particles 71 are present on the electrode pattern 21, and FIG. 7B shows a case where the depression 22 is present in the electrode pattern 21. FIG. 6 is a process chart showing the steps of the mounting state inspection method.

  In the substrate mounting state inspection method in the present embodiment, first, the periphery of the overlapping portion of the electrode pattern 21 and the bump 61 provided on the electronic component 6 is differentiated by the camera 3 provided on the substrate mounting state inspection device 10. An image is taken from the back side of the transparent substrate 21 through the interference optical system 4, and the electronic image data 100 around the crimped portion between the electrode pattern 21 and the bump 61 is acquired (layer imaging step: step P).

  Then, the image data 100 acquired in step P is binarized by the image processing device 5 provided in the substrate mounting state inspection device 10 with a predetermined gradation K as a threshold value, and is converted into a bright pixel and a dark pixel. To separate. Then, the position and luminance of the center of gravity β of the dark pixel group which is an aggregate of dark pixels are obtained (dark part extraction processing: step Q). The gradation K, which is a threshold value, is set to a value between the luminance of the electrode pattern image 21a and the luminance of the hollow image 22a of the electrode pattern.

  Next, with respect to the center of gravity β of the dark pixel group obtained in Step Q as a base point, a predetermined specific direction M, that is, a direction M in which the contrast of the differential interference optical system 4 occurs and ± the specific direction M ± A total of four search lines are set in directions that form an angle of 90 degrees and −180 degrees, respectively, and within the predetermined distance from the center of gravity β of the dark pixel group, each of the pixels existing on each search line is the largest. The high brightness pixel δi (i = 1 to 4) having high brightness is searched. Then, the position and brightness of the high brightness pixel δi are acquired (high brightness pixel search process: step R).

Then, using the position and brightness of the center of gravity β of the dark pixel group obtained in step Q and the position and brightness of the plurality of high brightness pixels δi obtained in step R, the brightness change rate defined by Obtained for each search line (brightness change rate calculation processing: step S).
Luminance change rate = (difference between luminance of high luminance pixel δi and luminance of centroid β of dark pixel group / distance between centroid β of dark pixel group and high luminance pixel δi)

  Next, the maximum change rate Ε1 is obtained from the luminance change rates obtained in step S. Usually, Ε1 coincides with the change rate in the specific direction M (the direction in which the contrast of the differential interference optical system 4 is generated) (maximum change rate extraction process 1: step T).

  Then, the maximum change rate Ε2 is obtained from the change rate of the luminance in the search line direction set in a direction other than the specific direction M (maximum change rate extraction process 2: step U).

  Next, ΔΕ (= Ε1−Ε2), which is the difference between the luminance change rates E1 and E2, is calculated (change rate difference process: step V).

  Next, the difference ΔΕ in luminance change rate calculated in step V is compared with a threshold L (determination process: step W). Here, in the case of the conductive particle image 71a shown in FIG. 7A, a bright portion 71a1 having a higher brightness than the electrode pattern image 21a exists in the direction M in which the contrast intensity of the differential interference optical system 4 occurs, and the differential interference is present. Since there is only an electrode pattern image 21a having a low luminance except in the direction M in which the contrast of the optical system occurs, the luminance change rate difference ΔΕ is a large value. On the other hand, in the case of the recessed image 22a of the electrode pattern shown in FIG. 7B, since only the electrode pattern image 21a exists in the specific direction M (the direction in which the contrast of the differential interference optical system is generated), the luminance change rate The difference ΔΕ is a small value.

  Therefore, by setting the threshold value L to an appropriate value, if the difference Δ 輝 度 in the luminance change rate is larger than the threshold value L, it is determined that the dark pixel group extracted in step Q is the conductive particle image 71a. When it is smaller than L, it can be determined that the dark pixel group is the hollow image 22a of the electrode pattern.

  As described above, according to the present embodiment, since the conductive particle image 71a and the electrode pattern depression image 22a can be discriminated from each other, it is poorly connected to the electrode pattern 21 in which only a predetermined number or less of the conductive particles 71 exist. Can be determined.

It should be noted that the distance for searching for high-luminance pixels in step R is a distance determined based on the size of the dark pixel group extracted in step Q, for example, the long axis or surroundings when the dark pixel group is approximated to an equivalent ellipse If it is set to the number of pixels of the long or dark pixel group, it is not affected by other conductive particles 71 in the surrounding area or the depression 22 of the electrode pattern. In step R, the number of search lines is four, but the direction and the number of search lines may be changed depending on the shape of the conductive particle image 71a and the depression image 22a of the electrode pattern.

Further, in the present embodiment, it is determined whether the dark pixel group extracted in step Q is the conductive particle image 71a or the hollow image 22a of the electrode pattern, but actually the transparent substrate 21 and the IC chip In some cases, a foreign object is caught between the two. In this case, similarly to the conductive particle image 71a, the foreign object image has a large difference Δ 輝 度 in luminance change rate, so that the foreign object image and the electrode pattern depression image 22a can be identified. The foreign object and the electrode pattern 21 can be identified using a known mounting state inspection method.

  As described above, according to the present embodiment, the overlapping portion between the electrode pattern and the electrode provided on the electronic component is imaged from the back side of the transparent substrate through the differential interference optical system, and the electronic image data of the overlapping portion is obtained. Step P to acquire, Step Q for extracting a dark pixel group having a lower luminance than the luminance of the image of the electrode pattern from the electronic image data, and obtaining a position and luminance of the center of gravity of the dark pixel group, and the dark pixel A plurality of search lines having an angle of ± 90 degrees or less with respect to a specific direction and a direction opposite to the specific direction with respect to the center of gravity of the group are set, and the search lines are within a predetermined distance from the center of gravity. A step R for searching for a high-brightness pixel having the highest luminance among the pixels existing above for each of the plurality of search lines to obtain positions and luminances of the plurality of high-brightness pixels; Step S of obtaining the luminance change rate in the plurality of search line directions based on the position and luminance of the heart and the position and luminance of the plurality of high luminance pixels, and the maximum luminance change rate among the luminance change rates A step T for obtaining the maximum luminance change rate among the luminance change rates in the search line direction set in directions other than the specific direction, the luminance change rate obtained in step U, and the step Step V for obtaining a difference from the luminance change rate obtained by V and Step W for determining the type of the dark pixel group by comparing the difference in luminance change rate with a set value. The indentation caused by the conductive particles and the depressions formed in the electrode pattern can be identified. As a result, the connection state between the electrode pattern provided on the transparent substrate and the electronic component mounted on the transparent substrate can be accurately determined. Can be inspected.

  Further, according to the present embodiment, the specific direction M is the direction in which the intensity contrast of the observation image by the differential interference optical system 4 changes, so that the particles and the pattern dents can be easily identified.

  Furthermore, according to the present embodiment, since the predetermined distance is determined based on the size of the dark pixel group, it can be identified as a particle without depending on the size of the depression.

Embodiment 3 FIG.
The mounting state of the substrate may be inspected by combining the mounting state inspection method of the substrate shown in the first embodiment and the mounting state inspection method of the substrate shown in the second embodiment.

  For example, the mounting state inspection method in the second embodiment is further applied to the electrode pattern indentation 22 determined by the mounting state inspection method in the first embodiment, and the electrode pattern indentation 22 is applied in both inspection methods. By determining what is determined to be truly the depression 22, the inspection accuracy of the electronic component mounting state can be further improved. The application order of the mounting state inspection method in the first embodiment and the mounting state inspection method in the second embodiment is not limited to this. Further, the identification target is not limited to the recess 22 of the electrode pattern, but may be the conductive particles 71.

  In addition, the mounting state inspection method in the first embodiment and the mounting state inspection method in the second embodiment are applied in a superimposed manner, and what is determined to be the depression 22 of the electrode pattern in any of the inspections is determined to be a true depression 22. By doing so, the mounting state of the substrate can be more reliably inspected.

  In the first to third embodiments, the inspection of the liquid crystal substrate has been described as an example. However, the present invention is not limited to the inspection of the liquid crystal substrate, and the bright portion is adjacent to the dark portion in the captured image data 100. The present invention can be applied to an inspection for identifying both a target that exists and a target that does not have a bright part.

  DESCRIPTION OF SYMBOLS 1 Mounting stage, 2 Mounting substrate, 3 Camera (imaging means), 4 Differential interference optical system, 5 Image processing apparatus (image processing means), 6 IC chip (electronic component), 7 Anisotropic conductive material, 10 Mounting of substrate Condition inspection device, 20 transparent substrate, 21 electrode pattern, 21a electrode pattern image, 22 electrode pattern depression, 22a electrode pattern depression image, 61 bump (electrode) 71 conductive particles, 71a conductive particle image, 100 electronic image data .

Claims (10)

A mounting state inspection method for a substrate in which an electronic component is mounted on an electrode pattern provided on a transparent substrate via an anisotropic conductive material containing conductive particles,
(A) imaging an overlapping portion between the electrode pattern and an electrode provided on the electronic component from the back side of the transparent substrate through a differential interference optical system, and obtaining electronic image data of the overlapping portion; ,
(B) extracting a dark pixel group having a luminance lower than the luminance of the image of the electrode pattern from the electronic image data, and obtaining a position of the center of gravity of the dark pixel group;
(C) Search for a high-brightness pixel having the highest luminance from pixels existing within a predetermined distance with respect to a specific direction using the center of gravity of the dark pixel group as a base point, and obtain the position and luminance of the high-brightness pixel And steps to
(D) A plurality of search lines having an angle of ± 90 degrees or less with respect to the specific direction with the high luminance pixel as a center are set, and the plurality of search lines are within a predetermined distance from the high luminance pixel. Searching for a low-brightness pixel having the lowest brightness from the pixels existing above, and obtaining the brightness of the plurality of low-brightness pixels;
(E) obtaining a sum of differences between the luminance of the high luminance pixel and the luminance of the plurality of low luminance pixels;
(F) A substrate mounting state inspection method comprising: a step of determining a type of the dark pixel group by comparing a sum of the luminance differences and a set value.   In the step (F), it is determined that the dark pixel group is a depression formed in the electrode pattern when the sum of the brightness differences is equal to or less than the set value, and the sum of the brightness differences is greater than the set value. 2. The method for inspecting a mounting state of a substrate according to claim 1, wherein when the size is larger, the dark pixel group is determined to be the conductive particles. A mounting state inspection method for a substrate in which an electronic component is mounted on an electrode pattern provided on a transparent substrate via an anisotropic conductive material containing conductive particles,
(P) imaging an overlapping portion between the electrode pattern and the electrode provided on the electronic component from the back side of the transparent substrate through a differential interference optical system, and obtaining electronic image data of the overlapping portion; ,
(Q) extracting a dark pixel group having a lower luminance than the luminance of the electrode pattern image from the electronic image data, and obtaining the position and luminance of the center of gravity of the dark pixel group;
(R) A plurality of search lines having an angle of ± 90 degrees or less with respect to a specific direction and a direction opposite to the specific direction are set with a center of gravity of the dark pixel group as a base point, and within a predetermined distance from the center of gravity. Searching the high-brightness pixels having the highest luminance among the pixels existing on the plurality of search lines for each of the plurality of search lines, and obtaining the positions and luminances of the plurality of high-luminance pixels;
(S) obtaining a luminance change rate in the plurality of search line directions based on the position and luminance of the center of gravity of the dark pixel group and the positions and luminances of the plurality of high luminance pixels;
(T) obtaining a maximum luminance change rate from the luminance change rates;
(U) obtaining a maximum luminance change rate from the luminance change rates in the search line direction set in a direction other than the specific direction;
(V) obtaining a difference between the luminance change rate obtained in the step (S) and the luminance change rate obtained in the step (U) ;
(W) A method for inspecting a mounting state of a substrate, comprising: a step of determining a type of the dark pixel group by comparing a difference between the luminance change rates and a set value. In the step (W), when the difference in luminance change rate is equal to or less than the set value, it is determined that the dark pixel group is a depression formed in the electrode pattern, and the difference in luminance change rate is the set value. 4. The method for inspecting a mounting state of a substrate according to claim 3, wherein the dark pixel group is determined to be the conductive particles when larger than.   5. The substrate mounting state inspection method according to claim 1, wherein the specific direction is a direction in which contrast strength changes in an observation image of the differential interference optical system. 6.   6. The substrate mounting state inspection method according to claim 1, wherein the predetermined distance is determined based on a size of the dark pixel group. A mounting state inspection device for a substrate in which an electronic component is mounted on an electrode pattern provided on a transparent substrate via an anisotropic conductive material containing conductive particles,
Differential interference optics,
An imaging unit that images an overlapping portion of the electrode pattern and the electrode provided on the electronic component from the back surface side of the transparent substrate through the differential interference optical system, and forms electronic image data;
For the electronic image data,
(SB) extracting a dark pixel group having a luminance lower than that of the image of the electrode pattern from the electronic image data, and obtaining a position of the center of gravity of the dark pixel group;
(SC) Search for a high luminance pixel having the highest luminance from pixels existing within a predetermined distance with respect to a specific direction using the center of gravity of the dark pixel group as a base point, and obtain the position and luminance of the high luminance pixel Step to do,
(SD) A plurality of search lines having an angle of ± 90 degrees or less with respect to the specific direction with the high luminance pixel as a center are set, and the plurality of search lines are within a predetermined distance from the high luminance pixel. Searching for a low-brightness pixel having the lowest brightness from the pixels existing above, and obtaining the brightness of the plurality of low-brightness pixels;
(SE) obtaining a sum of differences between the luminance of the high luminance pixels and the luminance of the plurality of low luminance pixels;
(SF) determining the type of the dark pixel group by comparing the sum of the luminance differences with a set value ;
Mounting state inspection device substrate, comprising the. A mounting state inspection device for a substrate in which an electronic component is mounted on an electrode pattern provided on a transparent substrate via an anisotropic conductive material containing conductive particles,
Differential interference optics,
An imaging unit that images an overlapping portion of the electrode pattern and the electrode provided on the electronic component from the back surface side of the transparent substrate through the differential interference optical system, and forms electronic image data;
For the electronic image data,
(SQ) extracting a dark pixel group having a luminance lower than the luminance of the image of the electrode pattern from the electronic image data, and obtaining a position and luminance of the center of gravity of the dark pixel group;
(SR) A plurality of search lines having an angle of ± 90 degrees or less with respect to a specific direction and a direction opposite to the specific direction are set with a centroid of the dark pixel group as a base point, and within a predetermined distance from the centroid. Searching the high-brightness pixels having the highest luminance among the pixels existing on the plurality of search lines for each of the plurality of search lines, and obtaining the positions and luminances of the plurality of high-luminance pixels;
(SS) obtaining a luminance change rate in the plurality of search line directions based on the position and luminance of the center of gravity of the dark pixel group and the positions and luminances of the plurality of high luminance pixels;
(ST) obtaining a maximum luminance change rate from the luminance change rates;
(SU) obtaining a maximum luminance change rate from the luminance change rates in the search line direction set in directions other than the specific direction;
(SV) obtaining a difference between the luminance change rate obtained in the step (SS) and the luminance change rate obtained in the step (SU);
(SW) An image processing means for executing a step of determining a type of the dark pixel group by comparing a difference between the luminance change rates and a set value ;
Mounting state inspection device substrate, comprising the.   The substrate mounting state inspection apparatus according to claim 7 or 8, wherein the specific direction is a direction in which contrast strength changes in an observation image of the differential interference optical system.   10. The board mounting state inspection apparatus according to claim 7, wherein the predetermined distance is determined based on a size of the dark pixel group.

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