JP4750451B2 - Electronic component mounting position inspection method and electronic component mounting position inspection device - Google Patents

Description

  The present invention relates to an electronic component mounting position inspection method and an electronic component mounting position inspection apparatus for inspecting a mounting position of an electronic component mounted on a transparent insulating substrate.

  In the liquid crystal display device, a driving IC (driving circuit: electronic component) is connected to a glass substrate (transparent mounting substrate: transparent insulating substrate) sandwiched between two glass substrates and stacked on the lighting device. Is.

  For example, in a liquid crystal display device using a thin film transistor (TFT), thin film transistors are arranged in a matrix on one transparent insulating substrate (TFT substrate) of two transparent insulating substrates. And it is overlaid with the outer shape protruding from the other transparent insulating substrate (color filter substrate: CF substrate).

  One pixel is formed in each TFT, and an image signal sent to the pixel is controlled by turning the TFT on and off. A source wiring for inputting an image signal from the source electrode of each TFT is drawn out in parallel with the short side of the glass substrate, and an electrode pad (connection electrode) for connecting a driving IC near the end on the long side of the TFT substrate. Part) is formed.

  Also, gate wiring for turning on and off the TFT is drawn out from the gate electrode of each TFT in parallel with the long side of the TFT substrate, and the driving IC is connected near the end on the short side of the TFT substrate in the same manner as the source side. An electrode pad is formed.

  For example, in a mode in which a driving IC is mounted by a flip chip mounting method, an adhesive resin called an anisotropic conductive film (ACF) is attached to an electrode pad disposed on a portion where a TFT substrate at the end of the panel is projected. The driving IC is directly mounted through a conductive fine particle (conductive particle) dispersed in the substrate. The drive IC is mounted on the electrode pad via a bump formed on the drive IC.

  The mounting position of the driving IC mounted on the electrode pad can be inspected by the following method.

  For example, Patent Document 1 discloses a prior art for observing a raised state of a press-bonded portion of a conductive particle with respect to an electrode pad of a transparent insulating substrate with a differential interference microscope through the transparent insulating substrate.

  Here, a differential interference microscope is a microscope that can be observed as bright and dark brightness by emphasizing minute irregularities (bumps) that cannot be seen with a normal microscope by light interference, and has been used in a wide range of fields. .

  By using this differential interference microscope, it is possible to observe the deformation of the electrode pad slightly caused by the restoring force of the flat conductive particles sandwiched between the bump and the electrode pad so as to return to the original shape as brightness brightness. it can.

  Since the brightness contrast appears only at the position where the bump exists, the approximate mounting position of the driving IC can be inspected by observing the brightness contrast visually or by monitoring with a CCD camera or the like. it can.

JP 2003-269934 A

  However, when the mounting position of the driving IC is inspected by the above method, the number of brightness brightness and the distribution shape are slightly different for each product. In addition, because of human eye judgment, individual differences also occur, and quantitative measurement is not possible. For this reason, there is a possibility that a defective product with a shifted mounting position of the driving IC may flow out to the user.

  Therefore, the present invention can automatically and accurately inspect the mounting position of the electronic component mounted on the electrode pad by thermocompression bonding without depending on the individual difference of the inspector. An object is to provide a position method and an electronic component mounting position inspection apparatus.

The invention according to claim 1 inspects the mounting position of the electronic component when the electronic component is mounted on the electrode pad disposed on the transparent mounting substrate by pressure bonding through the conductive film containing conductive particles. In the electronic component mounting position inspection method, (A) a step of obtaining an observation image of the electrode pad through the transparent mounting substrate by a differential interference microscope as electronic image data, and (B) in the step (A) from the resulting said electronic image data, and a step of determining a position relative to the electrode pads of the assembly of light and dark representing the conductive particles, wherein step (B) is of the electrode pads from the external tangents of the aggregate the distance to the edge, characterized in that it comprises a step of determining the position of the assembly against the electrode pad.

According to a third aspect of the present invention, the mounting position of the electronic component is inspected when the electronic component is mounted on the electrode pad disposed on the transparent mounting substrate by pressure bonding through the conductive film containing conductive particles. An electronic component mounting position inspection apparatus, comprising: a differential interference microscope; an imaging device for converting an observation image of the electrode pad through the transparent mounting substrate by the differential interference microscope into electronic image data; and the electronic image data from an image processing apparatus for obtaining position relative to the electrode pads of the assembly of light and dark representing the conductive particles, the image processing apparatus, the distance from the circumscribing lines of the assembly to the edge of the electrode pad, wherein The position of the assembly with respect to the electrode pad is obtained .

  According to the first aspect of the present invention, the position of the bright and dark aggregate formed at the mounting position of the electronic component is obtained from the observation image of the electrode pad by the differential interference microscope. As a result, when inspecting the mounting position of the electronic component, it does not depend on individual differences of the inspector.

According to the third aspect of the present invention, the position of the bright and dark aggregate with respect to the electrode pad is obtained from the observation image of the bright and dark aggregate formed on the electrode pad with a differential interference microscope. As a result, it is possible to automatically and efficiently inspect the mounting position of the electronic component.

<Embodiment 1>
FIG. 1 is a diagram showing a configuration of an electronic component mounting position inspection apparatus according to the present embodiment.
As shown in FIG. 1, the electronic component mounting position inspection apparatus includes a differential interference microscope 8, a CCD (Charge Coupled Device) camera 12, and an image processing apparatus 13.

  The CCD camera 12 is an imaging device that photoelectrically detects an image of an electrode pad or the like observed with the differential interference microscope 8. The CCD camera 12 is connected to the differential interference microscope 8, and on the other hand, the CCD camera 12 is connected to the image processing device 13 via a cable 18. The image processing device 13 is connected to the display monitor 14.

  Here, as described above, the differential interference microscope 8 divides illumination light into two light beams by a special prism, and is a three-dimensional structure that raises a sample with interference colors and contrast of light and dark caused by interference of these lights. It is a microscope that can be observed with a feeling.

  The image processing device 13 is a device that can perform each image processing described later in accordance with an image processing program. The display monitor 14 is a device that displays a captured image that has been subjected to image processing by the image processing device 13.

In the differential interference microscope 8, as shown in FIG. 1, the structure described below is observed.
The structure is obtained by mounting an electronic component 2 such as a driving IC on a TFT substrate (transparent mounting substrate) 1. The electronic component 2 is mounted on the TFT substrate 1 via the electrode pad 3. A color filter substrate (CF substrate) 7 is bonded to the TFT substrate 1.

  FIG. 2 is an enlarged view showing a mounting state of the electronic component 2 mounted on the TFT substrate 1. An electrode pad 3 is disposed on the transparent TFT substrate 1. Also, bumps 4 are formed on the electronic component 2. The electronic component 2 is mounted on the TFT substrate 1 with the electrode pads 3 and the bumps 4 facing each other.

  Here, the electronic component 2 is mounted on the TFT substrate 1 by thermocompression bonding. The electronic component 2 is mounted on the TFT substrate 1 via an anisotropic conductive film 6 including conductive particles 5.

  Therefore, when the thermocompression treatment is performed, a plurality of minute irregularities due to the conductive particles 5 or the like are generated on the electrode pad 3 and are observed as brightness brightness and darkness 11 (FIG. 4) through the differential interference microscope 8. The

  In addition, this invention is not limited to the thing regarding the test | inspection of the said liquid crystal display device, If the electronic component 2 is mounted on the transparent mounting board like the TFT substrate 1 via the electrode pad 3, It can be inspected.

  Further, as shown in FIG. 1, the TFT substrate 1 on which the electronic component 2 is mounted is such that the back surface (the surface opposite to the mounting side) of the TFT substrate 1 faces the objective lens of the differential interference microscope 8. Has been placed. Therefore, in the differential interference microscope 8, an image of the electrode pad 3 is observed through the transparent TFT substrate 1.

  Next, the electronic component mounting position inspection method according to the present embodiment will be described based on the flowchart shown in FIG.

  First, the plurality of electrode pads 3 are observed using the differential interference microscope 8 (step S1). Here, the electrode pad 3 is observed through the transparent TFT substrate 1.

  The CCD camera 12 takes in the electrode pad 3 image obtained through the differential interference microscope 8 and detects it photoelectrically (that is, photoelectrically converts the differential interference microscope image into electronic image data) (step S2).

  Then, the electronic data image created by the CCD camera 2 is captured by the image processing device 3 (step S3). The electronic data image captured by the image processing device 3 is shown in FIG.

  As can be seen from the electronic data image in FIG. 4, a plurality of electrode pads 3 are included in the image. Further, in one electrode pad 3, a plurality of brightness and darkness 11 (aggregates of light and darkness 11) due to the conductive particles 5 generated during the thermocompression treatment are formed.

  Subsequently, since the contrast of the light and dark 11 may be weak, an enhancement process for enhancing the contrast is performed (step S4).

  Note that enhancement processing for enhancing the boundary of contrast includes primary differentiation processing, smoothing filter processing, Sobel filter processing, Laplacian filter processing, and the like.

  Next, in steps S5 to S7, the positions of the light and dark 11 aggregates representing the conductive particles with respect to the electrode pad 3 are obtained from the electronic image data.

  First, the reference position 16 of the electrode pad 3 is selected, for example, at the upper left corner. The reference position 16 is a point representing the electrode pad 3 and may be an arbitrary position on the electrode pad 3.

  Next, in step S5, a circumscribed line 15 circumscribing the light and dark 11 aggregate is drawn (see FIG. 5). The outer tangent line 15 is drawn so that the edge of the light and darkness 11 that is the outermost in the vertical direction and the horizontal direction of the aggregate of light and darkness 11 is detected by the luminance difference between the electrode pad 3 and the light and darkness 11 and touches that edge. Such processing can be easily performed using a known image processing technique such as pattern matching.

  Subsequently, in step S6, a square center point formed by the four circumscribing lines 15 is obtained. The center point is set as a representative point C representing the light and dark 11 aggregate.

  Subsequently, in step S7, a position D of the representative point C with respect to a predetermined reference point on the electrode pad 3 is obtained.

The position of the representative point C with respect to the predetermined reference point can be obtained, for example, as follows with reference to FIG.
FIG. 6 shows an observation image of the electrode pad 3 when the electronic component 2 is disposed on the electrode pad 3 in a shifted manner.

  First, the design position of the representative point C is obtained in advance as the design point R. That is, when the electronic component 2 is disposed on the electrode pad 3 as designed, the position of the representative point C of the light and dark 11 aggregate with respect to the reference position 16 is obtained as the design point R. The design point R is set as a predetermined reference point of the electrode pad 3.

  Next, the position of the representative point C is obtained with respect to a coordinate system having the design point R as the origin (for example, the short direction of the electrode pad 3 is the X axis and the long direction of the electrode pad 3 is the Y axis). In this way, the position of the representative point C with respect to a predetermined reference point (design point R in the above example) can be obtained.

  Through the above steps, the position of the light and dark 11 aggregate with respect to the electrode pad 3 can be obtained as the position of the representative point C with respect to the design point R.

  Since the assembly of the light and dark 11 is formed by the electronic component 2 mounted on the electrode pad 3, the position of the representative point C with respect to the design point R can be the mounting position of the electronic component 2 with respect to the electrode pad 3. it can.

  It is not necessary to select the design point R as the predetermined reference point of the electrode pad 3. For example, the reference position 16 may be selected as the predetermined reference point.

Next, in step S8, the quality of the mounting position of the electronic component 2 is determined from the position of the representative point C with respect to the design point R.
For example, when the position of the representative point C is within ± 10 μm in the X-axis direction (short direction of the electrode pad 3) and the Y-axis direction (longitudinal direction of the electrode pad 3) with the design point R as the origin. ("Yes" in step S8), the mounting position of the electronic component 2 to be inspected is determined to be "good (pass)" (step S9).

  On the other hand, if the position of the representative point C exceeds 10 μm in either the X direction or the Y direction (“No” in step S8), the mounting position of the electronic component 2 is “defective (not good). (Pass) ”(step S10).

As described above, in the electronic component mounting position inspection method according to the present embodiment, the position of the light and dark 11 aggregate formed at the mounting position of the electronic component 2 from the observation image of the electrode pad 3 by the differential interference microscope 8. Have gained.
As a result, when the mounting position of the electronic component 2 is inspected, it does not depend on individual differences among inspectors.

Further, in the electronic component mounting position inspection method according to the present embodiment, the position of the light / dark 11 aggregate is represented by the representative point C, and the position of the light / dark 11 aggregate with respect to the electrode pad 3 is the predetermined position of the electrode pad 3. It is given by the position of the representative point C with respect to the reference point (design point R in the above example).
As a result, the mounting position of the electrode pad 3 can be easily and quantitatively managed by the position of the representative point C.

In the electronic component mounting position inspection method according to the present embodiment, the representative point C is given by the center point of a rectangle that circumscribes the light and dark 11 aggregate.
As a result, the representative point C can be easily obtained using a known image processing technique such as pattern matching.

Further, in the electronic component mounting position inspection method according to the present embodiment, the design point R of the assembly of light and dark 11 is prepared in advance, and the mounting position of the electronic component 2 is determined by the representative point C of the assembly relative to the design point R Judging.
As a result, it is possible to easily and automatically determine the quality of the electronic component mounting position without depending on individual differences among inspectors.

In addition, the electronic component mounting position inspection apparatus according to the present embodiment includes an image processing apparatus 13 that can perform the above method.
As a result, the inspection of the mounting position of the electronic component 2 can be automatically performed.

  In the present embodiment, the representative point C representing the light-dark 11 aggregate is set to the center value of a quadrangle formed by the circumscribed line 15 circumscribing the light-dark 11 aggregate.

  However, it is not always necessary to select the representative point C as described above, and any point can be used as long as it can represent the light and dark 11 aggregate.

  For example, as shown in FIG. 7, a curve 19 that surrounds an assembly of light and dark 11 may be drawn, and the position of the center of gravity of the figure surrounded by the curve 19 may be used as the representative point C.

  Further, it is not always necessary to draw the outer tangent line 15, and it is only necessary to specify the position of the light and darkness 11 at the extreme end in the vertical and horizontal directions. It is possible to obtain the same information as when the outer tangent line 15 is drawn from the coordinates of the light and darkness 11 at such a position.

  Further, it is not always necessary to inspect the position of the light / dark 11 aggregate with respect to the electrode pad 3 by representing the light / dark 11 aggregate by the representative point C.

  For example, as shown in FIG. 8, after drawing the outer tangent line 15, the mounting position of the electronic component 2 can be inspected by the distance from the outer tangent line 15 to the edge of the electrode pad 3. That is, the distances D1 to D4 between the outer tangent line 15 drawn on the top, bottom, left and right in FIG. 8 and the edge of the electrode pad 3 are measured, and the mounting position of the electronic component 2 on the electrode pad 3 is inspected based on the distance. May be.

  If design values corresponding to the distances D1 to D4 are obtained in advance, it is easy to determine whether the mounting position of the electronic component 2 is good by measuring the distances D1 to D4 when the electronic component 2 is mounted and comparing it with the design values. It can be carried out.

<Embodiment 2>
The electronic component mounting position inspection apparatus according to the present embodiment is configured to measure the distance between adjacent light and dark 11 for each light and dark 11 by the image processing device 13.

  Other configurations are the same as those in the first embodiment, and the same components are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 9 is a schematic diagram showing an observation image of the electrode pad 3 when the electronic component 2 is arranged with a large displacement. As a result of the electronic component 2 being greatly displaced, the light and darkness 11 due to the adjacent bumps 4 is observed in the region of one electrode pad 3.

  Then, as shown in FIG. 9, when the circumscribed line 15 circumscribing the aggregate of the light and dark 11 is drawn, the quadrangle formed by the circumscribed line 15 overlaps the electrode pad 3 without misalignment.

  In the case of determining the positional deviation based on the square center point, the center point is located substantially at the center of the electrode pad 3, so that the electronic component 2 is not greatly displaced even though the electronic component 2 is greatly displaced. May give incorrect results.

  In order to solve this problem, the electronic component mounting position inspection method according to the present embodiment performs the operation described below.

  FIG. 10 is a flowchart for explaining the electronic component mounting position inspection method according to the present embodiment.

  In accordance with the same procedure as in the first embodiment, an electronic data image of the electrode pad 3 is captured and an enhancement process is performed (steps S1 to S4, see FIG. 3).

  Subsequently, the distance L in the horizontal direction (short direction of the electrode pad 3) to the adjacent light and dark 11 is measured for each light and dark 11 (step S21).

  Next, in step S22, the quality of the mounting position of the electronic component 2 is determined from the distance L.

  First, a certain distance Ls is prepared in advance as a criterion for determining whether or not the product is acceptable. The distance Ls is selected to be smaller than the distance between the bumps 4. When the distances L between the light and dark portions 11 having a plurality of luminances are respectively measured and smaller than the distance Ls (“Yes” in step S22), the mounting position of the electronic component that is the inspection target is “good (passed)”. Judgment is made (step S23).

  On the other hand, if the distance L is more than the distance Ls (“No” in step S22), the mounting position of the electronic component 2 to be inspected overlaps the adjacent electrode pad 3 As “bad (failed)” (step S24).

  Thereafter, by performing the processing of steps S5 to S9 described in the first embodiment, the mounting position of the electronic component 2 can be inspected without error.

  For example, in the case shown in FIG. 11, the lateral distance L from the light / dark 11a to the light / dark 11b adjacent to the light / dark 11a is equal to or greater than the distance Ls, so that it is determined to be defective.

  Here, in the present embodiment, it has been described that steps S21 to S24 are performed before the processing of steps S5 to S9 (FIG. 3), but may be performed later.

  As described above, the electronic component mounting position inspection method according to the present embodiment can reliably prevent erroneous determination of the mounting position due to the electronic component 2 being greatly displaced.

In addition, the electronic component mounting position inspection apparatus according to the present embodiment includes an image processing apparatus 13 that can perform the above method.
As a result, it is possible to automatically inspect the mounting position of the electronic component 2 while reliably preventing erroneous determination of the mounting position due to the electronic component 2 being greatly displaced.

It is a figure which shows the structure of the electronic component mounting position inspection apparatus which concerns on Embodiment 1. FIG. 4 is an enlarged view showing a mounting state of an electronic component mounted on the TFT substrate according to Embodiment 1. FIG. 3 is a flowchart illustrating an electronic component mounting position inspection method according to the first embodiment. 4 is a diagram showing an electrode pad observed by a differential interference microscope according to Embodiment 1. FIG. It is a figure which shows the state which drawn the circumscribed line which circumscribes the brightness of the brightness | luminance which concerns on Embodiment 1. FIG. FIG. 6 is a diagram for explaining the electronic component mounting position inspection method according to the first embodiment. FIG. 10 is a diagram for explaining another method for determining a representative point of a luminance brightness / darkness assembly according to Embodiment 1; FIG. 10 is a diagram for explaining another method for determining a representative point of a luminance brightness / darkness assembly according to Embodiment 1; FIG. 10 is a diagram for explaining an electronic component mounting position inspection method according to the second embodiment. 10 is a flowchart illustrating an electronic component mounting position inspection method according to a second embodiment. FIG. 10 is a diagram for explaining an electronic component mounting position inspection method according to the second embodiment.

Explanation of symbols

1 TFT substrate, 2 electronic components, 3 electrode pads, 4 bumps, 5 conductive particles, 6 thermosetting resin, 7 CF substrate, 8 differential interference microscope, 9 objective lens, 10 eyepiece lens, 11 brightness contrast, 12 CCD camera, 13 image processing device, 14 display monitor, 15 external tangent line, 16 reference point, C representative point, R design point.

Claims (4)

An electronic component mounting position inspection method for inspecting a mounting position of the electronic component when the electronic component is mounted on an electrode pad disposed on a transparent mounting substrate by pressure bonding through a conductive film containing conductive particles. ,
(A) A step of obtaining an observation image of the electrode pad through the transparent mounting substrate by a differential interference microscope as electronic image data;
(B) From the electronic image data obtained in the step (A), obtaining a position of the bright and dark aggregate representing the conductive particles relative to the electrode pad;
With
Wherein step (B) is the distance from the circumscribing lines of the assembly to the edge of the electrode pad, an electronic component mounting position inspection, which comprises the step of determining the position of the assembly against the electrode pad Method. (C) The electronic component mounting position inspection method according to claim 1, further comprising the step of determining whether the electronic component mounting position is good or not based on the position of the assembly with respect to the electrode pad. An electronic component mounting position inspection apparatus for inspecting the mounting position of the electronic component when mounting the electronic component on an electrode pad disposed on a transparent mounting substrate by crimping via a conductive film containing conductive particles. ,
Differential interference microscope,
An imaging device that converts the observation image of the electrode pad through the transparent mounting substrate by the differential interference microscope into electronic image data;
An image processing device for obtaining a position of the light and dark aggregate representing the conductive particles with respect to the electrode pad from the electronic image data;
The image processing apparatus obtains the position of the assembly with respect to the electrode pad based on a distance from a circumscribing line of the assembly to an edge of the electrode pad.
An electronic component mounting position inspection apparatus characterized by the above. The electronic component mounting position inspection apparatus according to claim 3, wherein the image processing apparatus determines whether the electronic component mounting position is good or not based on a position of the assembly with respect to the electrode pad.

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