JP5132610B2 - Electronic component mounting state inspection apparatus and electronic device manufacturing method - Google Patents

Description

  The present invention relates to an electronic component mounting state inspection apparatus and an electronic device manufacturing method, and more particularly, to an electronic component in a case where the electronic component is mounted on a transparent substrate provided with electrodes via an anisotropic conductive film by thermocompression bonding. The present invention relates to a mounting state inspection apparatus and a method for manufacturing an electronic device.

  Conventionally, as a mounting state inspection method when an electronic component is mounted by thermocompression bonding through an anisotropic conductive film, there is a method using that the electrical resistance value is increased when the mounting state is insufficient. As this method, in addition to a method of actually measuring the electric resistance value of the mounting portion, a method of confirming a function achieved when the electrical connection is correctly performed is known. For example, when the electronic component for display control of the liquid crystal display is mounted on the glass substrate of the liquid crystal display, whether or not the mounting state is good can be determined by actually displaying the screen of the liquid crystal display.

  There is also a method of directly observing the state of the mounting part. For example, it is mounted by the number of parts that a human observes with a differential interference microscope from the back in the mounting direction, and determines that the electronic component is an impression formed on the electrode by mounting by thermocompression bonding through an anisotropic conductive film. The state is judged as good or bad.

  There is also a method of automating this method. For example, Patent Document 1 describes a method of taking an image of an electrode portion using a differential interference microscope and determining whether or not an indentation is based on the shape of a raised portion present in the taken image. ing. Patent Document 2 describes a method for determining whether or not an impression is based on the area and shape of white or black when a captured image is similarly binarized. Furthermore, Patent Document 2 also describes a method of measuring the strength of bonding by obtaining the standard deviation of the gray value of the inspection range in the electrode.

  When the mounting state of the electronic component is not determined to be good by these automated methods, the mounting state of the electronic component may be truly defective or may be really good. In that case, the electronic component is carried out to a re-inspection process, and a final determination is made as to whether the mounting state is good or not by visual inspection by a human.

JP 2003-269934 A JP 2005-227217 A

  As described above, when the mounting state of the electronic component is not determined to be good by the conventional automatic inspection method, there is a possibility that the mounting state of the electronic component is truly bad and may be really good. is there. The case of being truly good is, for example, a case where a large number of indentations are concentrated on the electrode, and the case of being truly defective is, for example, a case where foreign matter such as dust is mixed in the electronic component. .

  Conventionally, however, it has not been possible to distinguish between densely indented marks and foreign matters, so that not only electronic components in which foreign matter is sandwiched but also electronic components in which densely indented impressions are formed are determined to be defective. If an electronic component having such densely formed indentations is determined as a defective product, it is carried out to a reinspection process such as a visual inspection, which causes a decrease in inspection efficiency.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electronic component mounting state inspection apparatus and electronic device that can avoid a problem that a dense indentation is regarded as a foreign matter in an automatic inspection process. It is to provide a device manufacturing method.

  A first feature according to an embodiment of the present invention is that, in the electronic component mounting state inspection apparatus, a surface on which the electronic component is pressure-bonded and mounted on a transparent substrate on which the electronic component is pressure-bonded and mounted via an anisotropic conductive film Imaging means for imaging with a differential interference microscope from the back side of the image, a specifying means for specifying the height of the convex portion included in the image picked up by the imaging means, and the convex shape specified by the specifying means Determining means for determining whether or not the height of the portion exceeds a predetermined threshold value, and determining that a foreign object is mixed when the height of the convex portion exceeds the predetermined threshold value.

  According to a second feature of the present invention, in the method for manufacturing an electronic device, an electronic device production process in which the electrode of the electronic component is bonded to the electrode of the transparent substrate through the conductive fine particles, and is anisotropic. An imaging process in which a transparent substrate on which an electronic component is pressure-bonded and mounted through a conductive conductive film is imaged by imaging with a differential interference microscope from the back side of the surface on which the electronic component is pressure-mounted, and an image captured in the imaging step A specifying step for specifying the height of the convex portion to be included; and determining whether the height of the convex portion specified in the specifying step exceeds a predetermined threshold; A determination step of determining that a foreign substance is mixed when a predetermined threshold value is exceeded.

  According to the present invention, since it is possible to correctly determine whether or not foreign matter is mixed in the automatic inspection process, it is possible to mount an electronic component that can avoid the problem that the densely indented impression is regarded as foreign matter mixed in the automatic inspection process. It is possible to provide a state inspection apparatus and a method for manufacturing an electronic device. As a result, the electronic component on which the dense indentation is formed is determined as a defective product and is not carried out to a re-inspection process such as a visual inspection, so that the inspection efficiency can be improved.

It is a figure which shows the structure of the mounting state inspection apparatus of the electronic component which concerns on embodiment of this invention. It is a figure which shows the structure of the test target object which concerns on embodiment of this invention. It is a figure which shows the structure of the differential interference microscope which concerns on embodiment of this invention. It is a figure which shows the structure of the test target object which concerns on embodiment of this invention. It is a figure which shows the structure of the test target object which concerns on embodiment of this invention. It is a figure which shows the conventional foreign material determination method. It is a figure which shows the conventional foreign material determination method. It is a figure which shows the foreign material determination method which concerns on embodiment of this invention. It is a figure which shows the foreign material determination method which concerns on embodiment of this invention. It is explanatory drawing of the differential interference direction which concerns on embodiment of this invention. It is a flowchart which shows the mounting state test | inspection process which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of an electronic component mounting state inspection apparatus X according to an embodiment of the present invention. As shown in FIG. 1, the mounting state inspection apparatus X includes an XY stage 5, a differential interference microscope 6, a CCD camera 7, a display unit 8, a cleaning device 9, and a control unit 10. The display unit 8 displays the inspection content and the inspection result. On the XY stage 5, an inspection object 4 in which an electronic component 3 is mounted on a transparent substrate 1 via an anisotropic conductive film 2 is placed.

  FIG. 2 is a diagram showing a configuration of the inspection object 4 according to the embodiment of the present invention. As shown in FIG. 2, an electrode 11 is provided on one surface of the transparent substrate 1, and an electronic component 3 is mounted via an anisotropic conductive film 2 on the side where the electrode 11 is provided. The electronic component 3 is mounted by thermocompression bonding. The anisotropic conductive film 2 is a film in which conductive particles 2b are dispersed in an adhesive resin 2a having insulating properties. When the electronic component 3 is mounted, the conductive particles 2b are sandwiched between the bumps 3a and the electrodes 11 of the electronic component 3 and are crushed, so that the bumps 3a and the electrodes 11 can be energized. Further, when the conductive particles 2b sandwiched between the bumps 3a and the electrodes 11 are pressed, the electrodes 11 are formed with indentations 11a that are the marks pressed by the conductive particles 2b.

  FIG. 3 is a diagram showing a configuration of the differential interference microscope 6 according to the embodiment of the present invention. As shown in FIG. 3, the differential interference microscope 6 includes a pair of wedge-shaped prisms 12a and 12b, which are interference devices, incorporated in a normal optical microscope, and changes in the refractive index and thickness of the sample are shaded. It is a known microscope that can be observed instead of the difference. By using the differential interference microscope 6, minute convex portions (for example, the indentation 11 a) of the electrode 11 that cannot be observed with a normal optical microscope can be observed as a difference in light and shade. The differential interference microscope 6 is arranged in a direction to project the transparent substrate 1 on which the electronic component 3 is mounted from the back side of the surface on which the electronic component 3 is mounted.

  The differential interference microscope 6 is provided with an adjustment mechanism (not shown) for adjusting the position of the movable prism 12b with respect to one fixed prism 12a. By moving the prism 12b by this adjusting mechanism, the observable contrast can be adjusted. Therefore, by adjusting the position of the prism 12b at the time of manufacturing the differential interference microscope 6, it becomes possible to obtain the same shade difference when each differential interference microscope 6 projects the same inspection object 4.

  The brightness of the illumination of the differential interference microscope 6 can be adjusted so as to be constant by using the average of the gray values of the captured images and an illuminometer. By performing this illuminance adjustment, the same light and shade difference can be obtained when each differential interference microscope 6 projects the same inspection object 4.

  The CCD camera 7 is an example of an imaging unit according to the present invention. The CCD camera 7 is provided integrally with the differential interference microscope 6 and captures an image projected by the differential interference microscope 6.

  The cleaning device 9 cleans the surface of the transparent substrate 1 on the side projected by the differential interference microscope 6. If dust adheres to the surface of the transparent substrate 1 on the side projected by the differential interference microscope 6, it will interfere with taking an image of the electrode 11 due to the influence, and the indentation 11 a cannot be detected, or foreign matter may be in contact with the electrode 11. It may be determined that the object is sandwiched between the bumps 3a. In order to prevent such a problem, it is preferable to clean the transparent substrate 1 in advance. When the frequency of dust adhesion is low, the portion is cleaned only when the indentation 11a cannot be detected or when it is determined that a foreign object is sandwiched between the electrode 11 and the bump 3a. May be. As a cleaning method, there are a method of removing dust by blowing gas, a method of sucking dust, a method of removing dust with a brush, and the like. In the case of cleaning with a brush, it is effective to combine brush rotation and parallel movement. That is, if only the rotation is performed, the rotational center becomes zero speed, and thus the foreign matter in this portion cannot be removed. On the other hand, if only translation is performed, there is a possibility of moving dust to the adjacent inspection range.

  The control unit 10 is an example of a specifying unit and a determining unit according to the present invention, and includes a ROM, a RAM, a CPU, and a storage unit. The ROM stores various programs and various fixed data. The RAM temporarily stores data input from the differential interference microscope 6 and the CCD camera 7. The CPU performs various arithmetic processes using programs and fixed data stored in the ROM and data stored in the RAM. The storage unit stores a part of the input data and the calculation result by the CPU in association with the inspection object 4. In addition, as will be described later, the control unit 10 stores a threshold value of density information that can distinguish between the foreign matter 21 and the dense pressure mark 11b.

  4 and 5 are diagrams showing the configuration of the inspection object 4 according to the embodiment of the present invention.

  Specifically, FIG. 4 shows a state in which the foreign material 21 is sandwiched between the bump 3 a and the electrode 11. On the other hand, FIG. 5 shows a state in which the conductive particles 2 b are densely sandwiched between the bump 3 a and the electrode 11, and a dense pressure mark 11 b is formed on the electrode 11. As already explained, in the conventional automatic inspection method, the dense indentation mark 11b and the foreign matter 21 cannot be distinguished. Hereinafter, this point will be described in more detail.

  6 and 7 are diagrams illustrating a conventional foreign matter determination method.

  Specifically, FIG. 6 shows a state in which foreign matter determination is performed on the electrode portion (see FIG. 4) between which the foreign matter 21 is sandwiched. On the other hand, FIG. 7 shows a state in which foreign matter determination is performed on the electrode portion (see FIG. 5) where the dense pressure marks 11b are formed. As shown in these drawings, conventionally, a filter process and a binarization process are performed on an image picked up using a differential interference microscope, and the foreign matter 21 depends on the area of white or black contained in the binarized image. Or indentation 11a.

  However, according to this determination method, the image processing is performed on the electrode portion on which the foreign matter 21 is sandwiched (see FIG. 6B) and the electrode portion on which the dense pressure marks 11b are formed. The result (see FIG. 7B) cannot be distinguished. That is, in any case, the area of white included in the binarized image becomes an area of a certain value or more. For this reason, conventionally, not only the electronic component in which the foreign substance 21 is sandwiched but also the electronic component in which the dense pressure indentation 11b is formed is determined as a defective product.

  In order to solve such a problem, the present inventors paid attention to the difference in height between the foreign matter 21 and the dense indentation mark 11b. That is, the foreign material 21 and the densely indented mark 11b are greatly different in the size occupied between the bump 3a and the electrode 11, and there is a clear difference in height between the two. For example, as shown in FIG. 4, the height h1 of the foreign material 21 is about several hundred nm. On the other hand, as shown in FIG. 5, the height h2 of the dense indentation mark 11b is about several tens of nanometers.

  The differential interference microscope 6 is suitable for counting the number of irregularities because the irregularities change remarkably. However, the height of the convex portion (absolute value indicating the degree of swelling) is not known. However, in order to correctly inspect the mounting state, it is important to specify not only the unevenness change but also the height of the convex portion. Therefore, in the present invention, the height of the convex portion is specified by the method described below, and it is determined whether or not the foreign material 21 is mixed based on the height.

  8 and 9 are diagrams showing a foreign object determination method according to the embodiment of the present invention.

  Here, a state in which integration processing is performed in the differential interference direction on the density information of the image data captured by the CCD camera 7 is shown. The “differential interference direction” refers to the direction in which differential interference is performed in the differential interference microscope 6 (the direction in which the focus is shifted), which will be described in detail later. “Applying integration processing” refers to an operation of cumulatively calculating density information for each pixel, for example.

  FIG. 8 shows a state in which the integration processing is performed on the image data in the mounted state including one indentation 11a and a lump of dense indentations 11b. On the other hand, FIG. 9 shows a state in which integration processing is performed on image data in a mounted state including one indentation 11a and one foreign material 21. FIG. 8 and FIG. 9 both show a state before (a) the integration process and (b) a state after the integration process. The vertical axis represents the brightness (density information) of the image data, and the horizontal axis represents the position information in the differential interference direction.

  Here, the dense indentation 11b is a state in which the indentations 11a are gathered. For this reason, a change in the density value appears for each indentation 11a, but as shown in FIG. On the other hand, in the case of the foreign substance 21, as shown in FIG. 9A, the density value gradually changes over a long section in the differential interference direction. Therefore, the integration processing is performed on the image data in the mounting state in which the dense pressure marks 11b are formed (see FIG. 8B) and the image data in the mounting state in which the foreign material 21 is sandwiched. A large difference is observed in the peak value of the brightness of the integral image data from the result of the processing (see FIG. 9B). This difference is caused by a difference in the physical height of the material sandwiched between the bump 3a and the electrode 11. In other words, by performing integration processing in the differential interference direction on the density information of the image data imaged by the CCD camera 7, the height of the convex portion included in the image data can be specified. The “height” here may be an index of height, and the unit is not particularly limited.

  Therefore, the control unit 10 stores in advance a threshold value of density information that can distinguish the foreign substance 21 and the densely packed mark 11b. Then, it is determined whether or not the peak value obtained as a result of the integration process exceeds a predetermined threshold. If the peak value exceeds the predetermined threshold, it is determined that the foreign material 21 is mixed. In this way, it is possible to correctly determine whether or not the foreign matter 21 is mixed in the automatic inspection process, and therefore, it is possible to avoid the problem that the densely indented impression 11b is considered to be mixed with the foreign matter 21 in the automatic inspection step. It becomes possible.

  FIG. 10 is an explanatory diagram of the differential interference direction according to the embodiment of the present invention.

  As already described, the “differential interference direction” is the direction in which differential interference is caused in the differential interference microscope 6 (the direction in which the focus is shifted). Describing with reference to FIG. 10, the direction of light and darkness (arrow direction) in the image data captured by the CCD camera 7 corresponds to the differential interference direction. Here, since it is assumed that two lights are applied to the electrode 11 in an oblique direction, the direction from the upper left to the lower right is a light and dark direction in the drawing.

  Next, the operation of the mounting state inspection apparatus X according to the embodiment of the present invention will be described using the processing flowchart of the control unit 10 shown in FIG.

  First, when the inspection object 4 is conveyed to the inspection position projected by the differential interference microscope 6 (S1: YES), an image projected by the differential interference microscope 6 is captured by the CCD camera 7 (S2). When the imaging by the CCD camera 7 is completed, the position of the electrode 11 is detected from the captured image based on the shape pattern of the electrode 11 registered in advance (S3).

  When the position of the electrode 11 is detected, integration processing is performed on the detected image of the electrode 11 (S4), and it is determined whether or not the peak value resulting from this integration processing exceeds a predetermined threshold value. (S5). Here, when the peak value as a result of the integration processing exceeds a predetermined threshold (S5: YES), it is determined that the foreign material 21 is mixed (S6), and the foreign material determination operation ends. On the other hand, when the peak value as a result of the integration processing does not exceed the predetermined threshold (S5: NO), it is determined that the foreign material 21 is not mixed (S7), and the foreign material determination operation ends.

  As described above, according to the electronic component mounting state inspection apparatus X according to the embodiment of the present invention, it is possible to correctly determine whether or not the foreign material 21 is mixed in the automatic inspection process. In this case, it is possible to avoid the problem that the dense indentation mark 11b is regarded as the contamination of the foreign matter 21. As a result, the electronic component on which the dense indentations 11b are formed is determined as a defective product and is not carried out to a reinspection process such as a visual inspection, so that the inspection efficiency can be improved.

  Further, in the electronic component mounting state inspection apparatus X according to the embodiment of the present invention, a method of determining whether or not the foreign material 21 is mixed using the image data projected by the differential interference microscope 6 is adopted. Yes. As already described, in order to correctly inspect the mounting state, it is necessary to use the differential interference microscope 6 in order to know the change in the unevenness. Therefore, when the present invention is applied to an existing inspection apparatus that needs to use the differential interference microscope 6, there is an effect that it is not necessary to change the hardware configuration.

In addition, in FIG. 11, although demonstrated centering on the foreign material determination process among the mounting state inspection processes which concern on embodiment of this invention, the content of the mounting state inspection process other than a foreign material determination process is not specifically limited. . For example, when it is determined that the foreign matter 21 is mixed (S6), it may be determined that the mounting state is defective. On the other hand, when it is determined that the foreign matter 21 is not mixed (S7), the process may be shifted to the indentation determination operation.
The impression determination is to determine whether or not the number of impressions necessary for the specification of the mounting state of the non-defective product has been reached. For example, when the necessary number of indentations has been reached, it is determined that the mounting state is good. On the other hand, when the necessary number of impressions is not reached, it is determined that the mounting state is defective.

  The indentation determination method may be a general method. For example, it is possible to employ a method of binarizing an image captured by the differential interference microscope 6 and determining whether the indentation 11a is based on the area and shape of white or black when binarized. .

  Here, (A) the procedure for determining indentation after determining foreign matter has been described, but on the contrary, the procedure for determining foreign matter after performing (B) indentation determination may be adopted. (A) By adopting the procedure for determining the indentation after determining the foreign matter, there is an advantage that when the foreign matter 21 is mixed, it is possible to immediately determine that the mounting state is defective without performing the indentation determination. is there. On the other hand, if the procedure for determining foreign matter after (B) indentation determination is adopted, foreign matter determination is performed only when, for example, the area of white included in the binarized image in the indentation determination exceeds a certain value. There is a merit that it is good.

  Here, the integration processing is performed on the density information of the image data in order to specify the height of the convex portion, but the height of the convex portion may be specified by another method. Also in this case, if an appropriate threshold value is stored in the control unit 10 in advance, it can be determined whether or not the foreign material 21 is mixed by determining whether or not the threshold value is exceeded.

  Here, it is determined whether or not the peak value resulting from the integration process exceeds a predetermined threshold (S5 in FIG. 11), but the peak value resulting from the integration process is not necessarily obtained. There is no need. That is, as a result of the integration process, if there is a value (brightness) exceeding a predetermined threshold, it can be determined that the foreign material 21 is mixed regardless of whether the value is a peak value or not. It is.

  The content of the foreign material 21 is not particularly limited. That is, anything that adversely affects the mounting state of the electronic component 3, such as dust that should not be included, can be considered as the foreign material 21.

  DESCRIPTION OF SYMBOLS 1 ... Transparent substrate, 2 ... Anisotropic conductive film, 3 ... Electronic component, 4 ... Inspection object, 5 ... XY stage, 6 ... Differential interference microscope, 7 ... CCD camera, 8 ... Display part, 9 ... Cleaning apparatus, DESCRIPTION OF SYMBOLS 10 ... Control part, 11 ... Electrode, 11a ... Indentation, 11b ... Condensed indentation, 21 ... Foreign material.

Claims (3)

An imaging means for imaging a transparent substrate on which an electronic component is pressure-bonded and mounted through an anisotropic conductive film by imaging with a differential interference microscope from the back side of the surface on which the electronic component is pressure-bonded;
Specifying means for specifying the height of the convex portion included in the image picked up by the image pickup means;
It is determined whether or not the height of the convex portion specified by the specifying means exceeds a predetermined threshold, and if the height of the convex portion exceeds a predetermined threshold, it is determined that foreign matter is mixed in An electronic component mounting state inspection apparatus, comprising: a determination unit configured to perform the determination. The specifying means specifies the height of the convex portion by performing integration processing in the direction in which differential interference is performed in the differential interference microscope with respect to the density information of the image,
The electronic component mounting state inspection apparatus according to claim 1, wherein the determination unit uses, as the predetermined threshold value, a threshold value of density information that can distinguish a foreign object from a densely indented impression. An electronic device production process in which an electrode of an electronic component is crimped and bonded to an electrode of a transparent substrate through conductive fine particles;
An imaging step of imaging a transparent substrate on which an electronic component is pressure-bonded and mounted through an anisotropic conductive film by imaging with a differential interference microscope from the back side of the surface on which the electronic component is pressure-bonded, and
A specifying step of specifying the height of the convex portion included in the image captured in the imaging step;
It is determined whether or not the height of the convex portion specified in the specifying step exceeds a predetermined threshold, and if the height of the convex portion exceeds a predetermined threshold, it is determined that foreign matter is mixed in A method for manufacturing an electronic device, comprising: a determination step.

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