JPH07111332B2 - Appearance inspection method for thin plates - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin plate, that is, an IC lead frame or a TAB (Tape Automated).
The present invention relates to a method of inspecting the appearance of a tape for bonding. More specifically, firstly, the present invention relates to an inspection method for determining the presence or absence of deformation of a thin plate, especially a lead pin, and secondly, in addition to the presence or absence of deformation of the lead pin, the state of the front surface and the back surface, that is, scratches on the lead frame and the like. The present invention relates to an inspection method for determining the presence / absence of pits, pinholes, unevenness, stains, stains, and the quality of gloss. Thirdly, in addition to the above-mentioned deformation of lead pins and the quality of the front and back surfaces, pin holding The present invention relates to an inspection method for determining whether or not a fixing position of a tape adhesive or a tape is good or bad.

[0002]

2. Description of the Related Art In the past, visual inspection by a human eye was used as a visual inspection method for thin plate-like objects such as lead frames. However, due to the recent increase in the density of semiconductor elements, leadframes are becoming more and more pins, and in response to demands for production cost reduction, mass production, and homogenization of quality, the appearance inspection of leadframes is also automated.・ Higher speed and higher accuracy are required. Therefore, recently, a television camera system using a CCD (charge coupled device) is often used as a visual inspection means for a lead frame or the like.

The outline thereof is as follows: A thin plate-like object such as a lead frame is transferred to an inspection position, an inspection request signal is output, its appearance is photographed by a CCD television camera, and an image obtained by image processing the image is obtained. By comparing and collating the pattern with a reference pattern for comparison and collation designed in advance by a CAD system, it is possible to determine whether the lead pin is deformed or not, and whether or not each item such as scratches and stains on the front and back surfaces is good or bad (for example, See Japanese Patent Application Laid-Open No. 2-226481).

[0004]

However, the above-mentioned appearance inspection means is normally discriminated by comparing and collating the image pattern obtained by image-taking by one CCD television camera provided at one place and image-processing. is doing. Therefore, the deformation of the lead pin of the thin plate-like object, the quality of the front and back surfaces, and the quality of the fixing position of the pin fixing adhesive or the like have to be determined separately.

Among the deformations of the lead pins, the presence or absence of deformation of the lead pin in the Z direction, that is, the thickness direction of the lead frame or the like is determined in the X direction, that is, the longitudinal direction of the lead frame or the like, or the Y direction, that is, the width of the lead frame or the like. Unlike the deformation of the lead pin toward the direction, 1 with the above CCD TV camera
It is impossible to determine by shooting only from the direction. This requires a plurality of CCD TV cameras, and when using a plurality of CCD TV cameras, it takes a lot of time to image-process the information obtained by each and obtain an image pattern to be compared and collated. become. Therefore, conventionally, the determination of the deformation of the lead pin in the Z direction is made by visual inspection.
It is difficult to inspect a large number of lead frames at a time, and individual differences tend to occur because the same standard is not used.

Further, since the depth of focus of a CCD television camera is generally shallow, it is not possible to accurately distinguish, for example, from scratches on the front and back surfaces of a lead frame or the like and deposits. A scratched product is a defective product, but if it is an adhered substance, it will be cleaned and it will be a good product.Therefore, it is necessary to rely on visual inspection to determine which one will hit, and there is a problem in terms of accuracy and inspection time. there were.

Moreover, since the image element of the CCD television camera is larger than the pixel of the laser beam, the resolution is poor.
Therefore, it is difficult to obtain data on fine irregularities and stains, and accurate determination cannot be performed. CCD
There is also a method of repeatedly inspecting by slightly shifting the scanning position of the TV camera, but that would take nearly twice as long as the inspection time. Further, it is conceivable to reduce the area of the image element of the CCD television camera, but this has a problem that the photosensitivity is lowered and the integration time for photoelectric conversion is long, and the inspection time is also long.

The present invention is intended to solve the problems of the conventional visual inspection means for thin plate-like objects such as IC lead frames and TAB tapes. That is, the first aspect of the present invention
It is an object of the invention to provide an inspection method for accurately determining the presence or absence of deformation in the Z direction of a lead pin such as a thin plate-like lead frame having a multi-pin structure. A second object is to provide an inspection method for accurately determining the quality of the front and back surfaces in addition to the determination of the presence or absence of the deformation. A third object is to provide an inspection method for accurately determining whether or not the fixing position of the pin holding adhesive or the like is good, in addition to the presence or absence of the deformation and the quality of the front and back surfaces.

[0009]

[Means for Solving the Problems]

1) The first aspect of the appearance inspection method for a thin plate-like object according to the present invention is that when the thin plate-like object 1 passes an appearance inspection position, a laser beam 2 is emitted from both front and back sides of the thin plate-like object 1. The front surface 3 and the back surface 4 are each scanned by repeatedly irradiating the front surface 3 and the back surface 4 at a constant angle θ from the front or rear of the line z orthogonal to the back surface and at a constant speed in the direction perpendicular to the transport direction, and the transmitted light 2a from the front side and the back side, respectively.
Is converted into a received electric signal by each of the light receiving sensors 8 on the back side and the front side, image processing is performed, three-dimensional information is obtained from the phase difference between the two two-dimensional images, and Z comparison is performed with a previously input reference pattern. The presence or absence of deformation of the lead pin 6 in the direction is determined (see FIGS. 1 and 2).

2) The second aspect of the appearance inspection method for a thin plate-like object according to the present invention is that when the thin plate-like object 1 passes the appearance inspection position, laser beam light 2 is emitted from both front and back sides of the thin plate-like object 1. Repeated irradiation is performed at a constant angle θ from the front or the rear of the line z orthogonal to the front and back surfaces and at a constant speed in the direction perpendicular to the transport direction,
The front surface 3 and the back surface 4 are respectively scanned, and the transmitted light 2a from the front side and the back side is detected by the respective light receiving sensors 8 on the back side and the front side.
Then, the image is converted into a received electric signal and image processing is performed, three-dimensional information is obtained from the phase difference between the two two-dimensional images, and the presence or absence of deformation of the lead pin 6 in the Z direction is checked by comparing and collating with a previously input reference pattern. discriminated, and compares each reflected light 2b from the surface 3 and the back 4, and image processing is changed to an electrical signal received by the front and back of the light receiving sensor 8, the reference pattern which enter the respective two-dimensional image in advance The collation is performed to determine the quality of the front surface 3 and the back surface 4 (see FIGS. 1 and 3).

3) A third aspect of the appearance inspection method for a thin plate-like object according to the present invention is that when the thin plate-like object 1 passes an appearance inspection position, a laser beam 2 is emitted from both front and back sides of the thin plate-like object 1. Repeated irradiation is performed at a constant angle θ from the front or the rear of the line z orthogonal to the front and back surfaces and at a constant speed in the direction perpendicular to the transport direction,
The front surface 3 and the back surface 4 are respectively scanned, and the transmitted light 2a from the front side and the back side is detected by the respective light receiving sensors 8 on the back side and the front side.
Then, the image is converted into a received electric signal and image processing is performed, three-dimensional information is obtained from the phase difference between the two two-dimensional images, and the presence or absence of deformation of the lead pin 6 in the Z direction is checked by comparing and collating with a previously input reference pattern. discriminated, and compares each reflected light 2b from the surface 3 and the back 4, and image processing is changed to an electrical signal received by the front and back of the light receiving sensor 8, the reference pattern which enter the respective two-dimensional image in advance By comparing, the quality of the states of the front surface 3 and the back surface 4 is determined, and the transmitted light 2a from the front and back sides, or the reflected light 2 from the front and back surfaces, respectively.
b is converted into an electric signal received by each light receiving sensor 8 and image-processed, and each two-dimensional image is compared and collated with a previously input reference pattern to determine the quality of the position of the pin fixing adhesive 7 or the like. (See FIGS. 1, 2 and 3).

In the above structure, the thin plate-like material 1 means an IC lead frame, a TAB tape or the like. The X direction means the longitudinal direction of the thin plate 1, the Y direction means the width direction of the thin plate 1, and the Z-axis direction means the thickness direction of the thin plate 1.

The above-mentioned deformation is especially X.
Deformation in the Y and Z directions. Note that the deformation includes etching defects, press defects, and the like. Also, the states of the front surface 3 and the back surface 4 include the presence / absence of scratches, pits, pinholes, unevenness, stains, stains, etc. on the front and back surfaces of the thin plate-like object 1 and unevenness of the plated portion. It also includes the presence / absence of stains / dirt / adhesion of foreign matter, and the quality of the plating's dimensional position and gloss. The position of the pin fixing adhesive 7 or the like means the fixing position of the adhesive 7 for holding the lead pin 6 or the tape.

The irradiation of the laser beam 2 from the front side and the irradiation of the laser beam 2 from the back side are performed so that the transmitted light 2a from one side does not interfere with the reflected light 2b of the other side.
The timing to repeat at a constant speed is staggered. Each light receiving sensor 8 which receives each laser beam light 2 receives each transmitted light 2a or reflected light 2b and converts it into an electric signal.

An image processing unit (not shown) by a computer is provided for performing image processing of the electric signal from the light receiving sensor 8 and comparing and comparing with a previously inputted reference pattern to make a determination. The two-dimensional image or three-dimensional information obtained from the phase difference of the two-dimensional image is compared and collated with the reference pattern input in advance, and the presence or absence of deformation of the lead pin 6, the quality of the front surface 3 and the back surface 4, the adhesion for pin fixing Software that can determine the quality of the fixed position of the agent 7 etc. is installed.

In the figure, 9 is a gap between pins of a thin plate-like object, 10 is a condenser lens, 11 is a polygon mirror, 12 is an fθ lens, 13 is a mirror, and 14 is a diffusion plate.

[0017]

Function: The thin plate 1 such as an IC lead frame or TAB tape is conveyed to the visual inspection position, and when the thin plate 1 passes the visual inspection position, laser beam light is emitted from both front and back sides of the thin plate 1. Irradiate 2. The irradiation of the laser beam 2 is carried out at a constant angle θ from the front or back of a line z orthogonal to the front and back surfaces of the thin plate-shaped object 1 and a direction perpendicular to the conveying direction (longitudinal direction of the thin plate-shaped object in the figure) ( In the drawing, the thin plate-shaped material is repeatedly performed at a constant speed in the width direction), and light is received by each of the light receiving sensors 8 on the front and back sides (see FIG. 1).

A) First, in the case of determining whether or not the deformation of the thin plate-like material described in 1) above, especially the deformation of the lead pin, is determined (FIG. 2).
See) Laser beam light 2 from both front and back sides of the thin plate 1
The thin plate-like object 1 is scanned from the front surface 3 and the back surface 4 by the irradiation. Within the irradiated laser beam 2,
Each transmitted light 2 that has passed through the space 9 between the pins of the thin plate-shaped object 1 and the other space 9
The light a is received by the respective light receiving sensors 8 on the back side or the front side. At this time, since the irradiation of the laser beam light 2 from the front side and the irradiation of the laser beam light 2 from the back side are shifted as described above, the transmitted light 2a from the front side is
Does not interfere with the reflected light 2b on the back side.

The transmitted light 2a received by each of the back and front light receiving sensors 8 is immediately converted into an electric signal and image-processed by an image processing unit to obtain a two-dimensional image.
By comparing and collating this two-dimensional image with a reference pattern for determining the presence or absence of deformation in the X and Y directions, which is input in advance, it is determined whether or not the lead pin 6 is deformed in the X and Y directions. Further, since each of the above two-dimensional images is due to each transmitted light 2a of the separate laser beam light 2 emitted from both front and back sides of the thin plate-like object 1, there is a phase difference between both two-dimensional images. There is. Therefore, three-dimensional information is obtained from this phase difference, and the three-dimensional information is compared and collated with a reference pattern for determining the presence / absence of deformation in the Z direction, which has been input in advance, to thereby lead pin in the Z direction. The presence or absence of deformation of No. 6 is determined.

B) Next, in the case of judging the quality of the front and back surfaces of the thin plate-like article described in 2) above (see FIG. 3), it is determined whether the thin plate-like article 1 is deformed by the transmitted light 2a. In addition to that, the laser beam light 2 emitted from both the front and back sides is reflected by the lead pins 6 and the like on the front and back sides of the thin plate-like object 1, and the reflected light 2b is reflected on each of the front and back sides. The light is received by the light receiving sensor 8. This is converted into an electrical signal in the same manner as above, and each two-dimensional image obtained by image processing is displayed on the table.
The state of the front surface 3 and the back surface 4 of the thin plate-like object 1, that is, scratches, pits, pinholes, unevenness, stains, etc. of the lead frame are compared by comparing with a reference pattern that has been input in advance for determining the quality of the back surface. -The presence / absence of dirt and the quality of gloss are also determined.

C) Furthermore, in the case of determining whether the fixing position of the pin fixing adhesive or the like described in 3) is good or bad (see FIGS. 2 and 3), the thin plate 1 is deformed by the transmitted light 2a. The presence or absence is determined, and the quality of the front and back surfaces of the thin plate 1 is determined by each reflected light 2b.
Each two-dimensional image obtained from a or each reflected light 2b is compared and collated with a reference pattern input in advance for position determination of the fixing adhesive 7 or the like. As a result, the quality of the fixing position of the pin fixing adhesive 7 or the tape is also determined.

In any of the above cases, the information based on the transmitted light 2a or the reflected light 2b obtained by scanning with the laser beam light is used as a two-dimensional image or three-dimensional information by the image processing unit as a reference pattern which is input in advance. It is determined by comparing and collating. Therefore, the accuracy of discrimination is C
Unlike the CD TV camera system and visual inspection, it is processed with high accuracy, and even in a large amount of inspection, there is no individual difference and it is accurate.

Particularly, the pixel by the laser beam 2 is C
Unlike a picture element of a CD TV camera, it has a small size and a good resolution, and since it does not have the drawback of a shallow depth of focus unlike a CCDD TV camera, it can accurately obtain information about fine irregularities and stains. The difference between scratches and dirt on the front and back of No. 1 can be accurately determined. Also CC
Unlike D TV cameras, there is no reduction in light sensitivity, so inspection time is shortened. Moreover, the deformation of the thin plate-like material, especially the deformation of the lead pins, the quality of the front and back surfaces,
It is possible to perform all the inspections such as the quality of the fixing position of the pin fixing adhesive.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1, FIG. 2 and FIG. 3 show an embodiment of the appearance inspection method of a thin plate-like object according to the present invention, in which a laser beam light is applied to the thin plate-like object 1 which moves the appearance inspection position. It is composed of a scanning unit that irradiates two, a light receiving unit, and an image processing unit.

In the scanning unit, the front surface 3 faces upward and the back surface 4 faces.
The laser diode as the light emitter 5, the condenser lens 10 for condensing the laser beam light 2, and the laser beam light 2 on the upper and lower sides of the thin plate-like object 1 which moves with the laser beam light 2 down. The polygon mirror 11 that rotates at a constant speed for repeatedly scanning the front and back surfaces of the thin plate 1, the fθ lens 12 that makes the amplitude of the repeated scanning equal to or larger than the width of the thin plate 1, and the laser beam light 2 on the surface of the thin plate 1.・ Mirror 1 for irradiating the back surface with a constant angle θ with respect to the perpendicular z, for example, 15 degrees
3 and 3 are provided.

Similarly to the scanning unit, the light receiving unit also has laser beam light 2 on the upper side and the lower side of the thin plate-like object 1, respectively.
A diffuser plate 14 for diffusing the transmitted light 2a and the reflected light 2b of
A detector as a light receiving sensor 8 is provided in order to receive the diffused transmitted light 2a and the reflected light 2b and convert them into electric signals.

A computer is used as the image processing unit, and as described above, the electric signal from the light receiving sensor 8 is subjected to image processing and compared with a reference pattern inputted in advance to make a determination, and is a two-dimensional image or a two-dimensional image. The three-dimensional information obtained from the phase difference of the image is compared and collated with the reference pattern that has been moved in beforehand, and the presence or absence of deformation of the lead pin 6, the quality of the condition of the front surface 3 and the back surface 4, the fixing position of the pin fixing adhesive 7, etc. Incorporates software that can determine the quality of each item. The reference pattern for comparison and matching may be input by CAD or a silhouette.

In the illustrated embodiment, the thin plate-like object 1 when passing through the appearance inspection position has a front surface 3 and a back surface 4 in an upper / lower relationship, but the present invention is not limited to this, and the front surface 3 / rear surface 4 has a left / right relationship. It may have a horizontally long vertical shape. In either case, the laser beam 2 is emitted from both the front and back sides of the thin plate 1, and the light emitters 5 may be provided on both sides of the thin plate 1. The laser beam light 2 from one light emitter 5 may be divided by a half mirror and irradiated from each side.

In the illustrated embodiment, the thin plate 1 is conveyed in the longitudinal direction, but it may be conveyed in the width direction, in which case the repeated irradiation of the laser beam 2 causes the thin plate 1 to be elongated. Done in the direction.

[0030]

As is apparent from the above, the appearance inspection method for a thin plate according to the present invention has the following effects. A) Check for deformation of the thin plate, especially for the lead pin.
Not only in the X and Y directions, but also in the Z direction can be accurately determined. That is, in the conventional one CCD TV camera system, it is possible to determine the presence or absence of deformation in the X and Y directions, but it is impossible to inspect in the Z direction, and a plurality of CCD TV cameras are provided. , Required complex image processing. On the other hand, in the appearance inspection method for a thin plate-like object according to the present invention, image processing is performed based on each transmitted light of each laser beam light from the front and back sides of the thin plate-like object. It becomes possible to obtain three-dimensional information, and by comparing and collating it with the reference pattern, the deformation of the lead pin in the Z direction can be easily, quickly and accurately determined.

B) In addition to the presence or absence of deformation of the thin plate-like material,
It is possible to accurately determine the quality of the front and back surfaces of the thin plate.
That is, in the conventional CCD television camera system, the depth of focus is generally shallow, so that it is not possible to accurately determine whether the thin plate-shaped object is a scratch or an adhered object on the front and back surfaces. Further, since the image element of the CCD television camera is relatively large, it is difficult to accurately determine the quality of the front and back surfaces because the resolution is poor and information about fine irregularities and stains cannot be obtained. On the other hand, in the appearance inspection method according to the present invention, laser beam light is repeatedly scanned from the front and back sides of the thin plate-like object to obtain information from each reflected light. Therefore, the resolution is good, and high-density information about fine irregularities and stains can be obtained,
By comparing this with the reference pattern, it becomes possible to accurately determine the quality of the state of the front and back surfaces, for example, the difference between scratches and stains. Further, since it is not necessary to rely on visual inspection for the final inspection, the time required for the visual inspection can be shortened.

(C) In addition to the presence or absence of deformation of the thin plate-like object and the quality of the front and back surfaces, the quality of the fixing position of the pin fixing adhesive or the like can be determined at the same time. That is, the conventional C
In the CD TV camera system, it is not possible to simultaneously judge whether the thin plate-like object is deformed, especially whether the lead pin is deformed, whether the condition of the front and back surfaces is good, or whether the fixing position of the pin fixing adhesive etc. is good. I had no choice but to inspect. On the other hand, in the appearance inspection method according to the present invention, each transmitted light from the front surface / front surface or each reflected light on the front surface / back surface is subjected to image processing by each light receiving sensor to obtain each two-dimensional image, and a reference image is obtained. By comparing and collating with the pattern, the quality of the position of the pin fixing adhesive or the like can be determined. Therefore, it is possible to determine whether or not the thin plate-like object is deformed, whether the front and back surfaces are in good condition, or whether the fixing position of the pin fixing adhesive or the like is good.

[Brief description of drawings]

FIG. 1 is a partially longitudinal perspective view of a main part in an embodiment of a method for inspecting the appearance of a thin plate-like material according to the present invention.

FIG. 2 is a partially longitudinal front view of the embodiment shown in FIG. 1 when inspecting the lead pin for deformation.

FIG. 3 is a partially longitudinal front view of the embodiment shown in FIG. 1 at the time of inspecting the quality of the front and back surfaces of the thin plate-like object.

[Explanation of symbols]

1-Thin plate 2-Laser beam light 2a
-Transmitted light 2b-Reflected light 3-Surface 4-
Back side 5-Light emitter 6-Lead pin 7-
Pin fixing adhesive 8-Light receiving sensor 9-Void 10-
Condensing lens 11-Polygon mirror 12-fθ lens 13
-Mirror 14-diffuser z-orthogonal line θ
-Constant angle

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location H01L 21/66 J 7630-4M 23/50 C

Claims (3)

[Claims] 1. When the thin plate 1 passes through a visual inspection position, a laser beam 2 is emitted from both the front and back sides of the thin plate 1, and a predetermined angle from the front or rear of a line z orthogonal to the front and back. Repeatedly irradiate at a constant speed in the direction perpendicular to the transport direction at θ.
The front surface 3 and the back surface 4 are each scanned, and the transmitted light 2a from the front side and the back side is converted into electric signals received by the respective light receiving sensors 5 on the back side and the front side, and image processing is performed.
Appearance inspection of a thin plate-like object, characterized in that three-dimensional information is obtained from the phase difference of the three-dimensional image, and whether or not the lead pin 6 is deformed in the Z direction is determined by comparing and collating with a previously input reference pattern. Method. 2. A laser beam 2 is emitted from both front and back sides of the thin plate 1 when the thin plate 1 passes an appearance inspection position, and a predetermined angle is applied from the front or rear of a line z orthogonal to the front and back. Repeatedly irradiate at a constant speed in the direction perpendicular to the transport direction at θ.
The front surface 3 and the back surface 4 are each scanned, and the transmitted light 2a from the front side and the back side is converted into electric signals received by the respective light receiving sensors 5 on the back side and the front side, and image processing is performed.
The three-dimensional information is obtained from the phase difference of the three-dimensional image, the presence or absence of deformation of the lead pin 6 in the Z direction is determined by comparison and collation with a previously input reference pattern, and each reflection from the front surface 3 and the back surface 4 is performed. The light 2b is received by each of the light-receiving sensors 5 on the front side and the back side, converted into an electric signal and image-processed, and each two-dimensional image is compared and collated with a previously input reference pattern to determine whether the states of the front surface 3 and the back surface 4 are good or bad. to determine the
A method for inspecting the appearance of a thin plate-shaped product, characterized by being 3. A laser beam 2 is emitted from both front and back sides of the thin plate 1 when the thin plate 1 passes an appearance inspection position, and a constant angle is applied from the front or rear of a line z orthogonal to the front and back. Repeatedly irradiate at a constant speed in the direction perpendicular to the transport direction at θ.
The front surface 3 and the back surface 4 are each scanned, and the transmitted light 2a from the front side and the back side is converted into electric signals received by the respective light receiving sensors 5 on the back side and the front side, and image processing is performed.
The three-dimensional information is obtained from the phase difference of the three-dimensional image, the presence or absence of deformation of the lead pin 6 in the Z direction is determined by comparison and collation with a previously input reference pattern, and each reflection from the front surface 3 and the back surface 4 is performed. The light 2b is received by each of the light-receiving sensors 5 on the front side and the back side, converted into an electric signal and image-processed, and each two-dimensional image is compared and collated with a previously input reference pattern to determine whether the states of the front surface 3 and the back surface 4 are good or bad. In addition to determining the above, each transmitted light 2a from the front and back sides, or each reflected light 2b from the front and back sides is received by each light receiving sensor 5 and converted into an electric signal for image processing, and each two-dimensional image is processed in advance. A method for inspecting the appearance of a thin plate-like object, characterized in that the quality of the position of the pin fixing adhesive 7 or the like is determined by comparing and collating with the input reference pattern.