JPH0815178B2 - IC visual inspection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention enables highly accurate measurement of the amount of bending between leads of an IC without complicating the device configuration.
Regarding the IC appearance inspection method, more specifically, the bending of the lead can be measured in the longitudinal direction and the width direction of the lead, and also in the lead thickness direction, that is, the lead floating amount can be measured with high accuracy. The present invention relates to an IC appearance inspection method capable of measuring these bending amounts in relation to each other and to a package by utilizing the characteristic of recognition.

[Conventional technology]

Conventionally, the inspection of the bending of the IC lead has been performed mainly by visual inspection, and it takes a lot of time and labor at present. In view of this situation, attempts have been made to automate the inspection of bending of IC leads. For example, insert type IC
Japanese Unexamined Patent Application Publication No.
There is a technology disclosed in 8-70110. This is mainly for the purpose of measuring the bending in the lead width direction, that is, the lead pitch, and as shown in FIG. 9, the light source g and the phototransistor or photodiode are sandwiched by the intermediate portion of the lead i to be inspected. A photodetector s for detecting the presence or absence of light is disposed so as to face each other so that the optical path l connecting the light source g and the photodetector s intersects the lead intermediate portion, and the IC is run to move the lead i to the optical path l. Is blocked, the blocked state of the optical path 1 is detected by a plurality of photodetectors s, and the pitch of the pulse train detected by the photodetectors s is measured to measure the lead pitch and the like. In this technique, the optical path 1 intersects with the lead intermediate portion to be measured in an orthogonal state. The optical path 1 is intersected at an intermediate portion of the lead i in an orthogonal state for the following reason.

Since the IC to be inspected has a deviation in the thickness direction of the lead (lifting of the lead), and the positioning error when setting the IC to the inspection device is unavoidable, the optical path 1 is orthogonal to the middle of the lead. By crossing in the state, it is intended to prevent the lead floating and the positioning error from causing a fatal obstacle to the measurement of the lead pitch. As shown in FIG. 10 (a), if the optical path 1 is assumed to be orthogonal to the tip of the lead, the optical path 1 is not blocked by the lead i when the IC setting position is displaced as shown by the alternate long and short dash line. Measurement is impossible. Also, as shown in FIG. 10 (b), the lead pitch cannot be measured when the lead has a float.
The same problem occurs when the optical path 1 and the lead i are not orthogonal to each other. For example, as shown in FIGS. 11 (a) and 11 (b),
When an image is taken from above the lead with an acute angle with respect to the lead, the lead cannot be captured even if the setting position is slightly displaced or the lead is displaced inward in the thickness direction. Further, even when the lead crosses the lead at an acute angle in the same manner, the lead may be looked up from below as shown in FIG. Needless to say about floating leads,
The package itself cannot get in the way of the lead. In each of these cases, when the optical path 1 is made orthogonal to the middle portion of the lead i, even if there is a misalignment of the setting position or floating of the lead as shown in FIGS. It is possible to reliably detect the presence of, and it is possible to measure the lead pitch in an extremely stable state. By thus intersecting the optical path 1 with the intermediate portion of the lead in an orthogonal state, the stability of the inspection device is guaranteed.

However, in this technique, since the optical path is intersected with the lead middle portion, all the data obtained is the data in the lead middle portion, and the information at the lead tip portion cannot be obtained.

However, the current mounting technology is shifting to surface mounting that enables high-density mounting, and ICs are also shifting from conventional insertion type ICs to surface mounting type ICs. What is a surface mount type IC?
(Hereinafter referred to as FIC), the tip of the lead is extended parallel to the upper and lower surfaces of the IC package, and this tip is the contact surface to the mounting board. The state of contact with the mounting board is extremely important, and therefore the bending of the lead tip must be closely monitored. Particularly in recent ICs, the number of pins is increasing, and the lead pitch tends to be narrowed more and more. From this sense as well, it is very important to detect the bending of the tip of the lead, especially the detection of floating of the lead. Assuming that such an FIC is described in Japanese Patent Laid-Open No.
When applying the technology described in 8-70110 to observe the bending of the lead tip, it is necessary to intersect the optical path with the lead tip, but it does not intersect with the optical path depending on the bending of each lead tip. There is also a lead, and the amount of bending cannot be measured for that lead. In addition,
Although the technique described in 58-70110 can detect whether or not the tip of the lead intersects the optical path, it cannot measure the exact position of the edge of the lead. Further, since the relationship between the lead and the package cannot be measured with this technique, a measurement error may occur if the package is set at the inspection position with a deviation from a predetermined arrangement state or a bent state.

In view of such a problem, recently, an apparatus for inspecting the bending of a lead by using an image processing technique has been developed. What is shown as FIG. 8 is an explanatory view showing an example of this apparatus. The FICa has leads arranged on each side of the package b having a rectangular shape in plan view, but in the illustrated example, the leads are opposed to each other in the package b for convenience of description.
The explanation will be given assuming that it exists only on the edge. Also, the size of FICa is shown larger than it actually is.

In this device, an image pickup device e is arranged in front of the projecting lead c1 to be inspected via an imaging lens f, and a light source g is arranged at a side position of the image pickup device e. Then, the entire lead c1 including the end surface d of the lead c1 is illuminated by the illumination light L emitted from the light source g, and the light reflected by the surface of the lead c1 is received by the image pickup device e to directly obtain the image of the lead c1. Then, this image is subjected to image processing by a signal processing device (not shown) to recognize the entire shape of the lead c1 and compare the shape with a standard pattern registered in advance in the electronic computer to detect bending of the lead. .

[Problems to be solved by the invention]

In such a bending inspection device, the reflected light on the surface of the lead c1 is received to recognize the outer shape of the lead.
Since the surface condition of the lead c1 is different for each IC, the mode of reflection of the illumination light on the surface of the lead c1 is not uniform.
There is a problem that it is difficult to recognize the outer shape of c1, and as a result, it is also difficult to increase the accuracy of lead bending inspection performed based on such recognition of the outer shape. Further, in the conventional bending inspection apparatus, the image pickup device is arranged so that its optical path is parallel to the extending direction of the lead tip portion as shown in FIG. 8, or the optical path is on the lead tip surface. Since it is arranged vertically above the lead tip so as to be orthogonal to it, it was not possible to inspect the bending in all the directions of the lead longitudinal direction, the lead width direction, and the lead thickness direction. Since the bending in the thickness direction, which is called so-called floating, hinders the contact of the lead with the mounting board, it is necessary to measure the amount of the bending with high accuracy. It was not possible to inspect at the same time as the bending in the direction and the lead width direction.

[Means for solving problems]

The present invention has been made in view of the present situation, and it is possible to accurately measure the bending amount of a lead in the lead longitudinal direction, the lead width direction, and the lead thickness direction without being affected by the surface condition of the lead. It is another object of the present invention to provide an IC appearance inspection method capable of measuring the amount of bending in relation to each other and to the package by utilizing the characteristic of image recognition.

The present inventor has noticed that the image information of the entire lead is not necessary to detect the bending of the lead, and the tip position of the lead is simply known, and the tip position is the silhouette image of the lead by the transillumination method. In addition, in order to simultaneously inspect bending and floating in the lead longitudinal direction and the lead width direction, the tip of the lead is imaged obliquely to obtain a silhouette image, and the silhouette image is imaged. The present invention has been completed to find out that it is possible to perform two-dimensional image recognition using a processing device.

The present invention which has achieved such a problem has the following contents. That is, on the side opposite to the protruding side of the lead to be inspected with the IC package sandwiched, a surface in the length direction of the lead that can capture an image without blocking the tip of the lead by the IC package and includes the lead edge. A device in which an image pickup device is arranged at a position that can image the tip of the lead in an oblique direction with a small acute angle with respect to and a lighting device is arranged behind the lead to be inspected viewed from the image pickup device. IC to use
An appearance inspection method, comprising the step of forming a silhouette image of a lead including an outline contour image of a lead tip edge on the image pickup device by transmitted illumination by the illumination device, and an image recognition process for the obtained silhouette image. And the step of extracting the lead edge pattern from the silhouette image and comparing this pattern with a standard pattern of a non-defective product registered in advance. As a result of comparison, the lead edge pattern obtained from the silhouette image is compared. Is deviated in the width direction of the lead with respect to the standard pattern, it is judged that the lead has a bend in the width direction, and the pattern of the lead tip edge obtained from the silhouette image is before and after the standard pattern in the longitudinal direction of the lead. If the lead length is not correct or the lead is floating, the lead obtained from the silhouette image If the deviation amount of the leading edge pattern from the standard pattern is within a preset allowable value, it is judged as a good product, and if it is outside the allowable value, it is judged as a defective product.

The principle of the present invention will be described with reference to FIGS. 1, 2, and 3. In the figure, 1 is an FIC, 2 is a lighting device, 3 is an imaging lens,
Reference numeral 4 is an imaging device. Here, a case will be described where the lead 5a located on the left side of the drawing among the leads 5a and 5b of the FIC 1 is inspected. The image pickup device 4 is positioned on the opposite side of the side where the lead 5a to be inspected protrudes with the package 6 sandwiched therebetween, while the illumination device 2 is viewed from the image pickup device 4 with the lead 5a.
The optical path connecting the illuminating device 2 and the imaging device 4 intersects with the surface in the length direction of the lead including the lead tip edge at a small acute angle α by being positioned behind the.

[Action]

The illumination light L illuminated from the illumination device 2 passes through the portion where the lead 5a exists, then passes through the imaging lens 3 and enters the image pickup device 4, and the image pickup device 4 receives the silhouette image 5 of the lead 5a.
Image a '. Since the lead 5a is illuminated obliquely from above with a small acute angle with respect to the top and bottom surfaces of the lead tip, the silhouette image 5a 'formed on the image pickup device 4 includes an upper side 7a and a lower side 7b of the lead tip 7. Of the left side 7c and the right side 7d, the portion corresponding to the lower side 7b appears as the leading edge 7b 'of the outer contour of the silhouette image. Since the tip edge 7b 'corresponds to the tip position of the lead 5a, if the lead 5a is bent, it will be reflected as a deviation of the position where the tip edge 7b' exists, and therefore the tip in the silhouette image 5a ' The amount of bending of the lead 5a can be measured by measuring the position of the edge 7b 'and comparing it with the position of the reference front edge. For example, when there is a bend, the leading edge 7b 'exists at the position shown by the imaginary line in FIG. The lead 5a may be bent in three directions: the lead width direction K, the lateral lead longitudinal direction W, and the lead thickness direction H. The lead width direction K is bent in the leading edge 7b '.
Is reflected as a displacement of the positions of both ends 7c 'and 7d' of the lead, and the bending in the lead longitudinal direction W and the lead thickness direction H is the leading edge 7
It is reflected as a deviation before and after the position of b '(left and right in FIG. 3). Therefore, in order to detect the bending amount in the lead longitudinal direction W with high accuracy, it is sufficient to set a large angle α formed by the light receiving direction of the imaging device 4 with respect to the surface in the length direction of the lead including the leading edge of the lead. It can be understood that α may be set to a small value in order to measure the bending amount in the lead thickness direction H with high accuracy, but generally, the bending of the lead 5a in the thickness H direction is likely to be a problem during wiring. It is preferable to set α as small as possible.

The measurement of the amount of bending performed on such a silhouette image including the image of the leading edge of the lead is performed by two-dimensional image recognition using an image processing device.

As described above, the present method forms the lead silhouette image including the image of the lead tip edge on the imaging device by the transillumination method, and measures the bending amount by performing two-dimensional image recognition on the obtained silhouette image. Therefore, the obtained image is not affected by the surface condition of the lead, and the bending amount of the lead can be measured with high accuracy. Further, since the bending of the lead clearly appears as a deviation of the tip edge position in the outer contour of the silhouette image, the bending can be easily recognized and it is also suitable for image recognition. Further, according to the present invention, since the optical path connecting the illumination device and the imaging device is intersected with the surface in the length direction of the lead including the lead tip edge with a small acute angle, the bend in the lead thickness direction is changed. , It can be measured at the same time as bending in the lead width direction.

〔Example〕

Next, details of the present invention will be described based on illustrated embodiments. FIG. 4 shows FI using the IC appearance inspection method according to the present invention.
It is explanatory drawing at the time of comprising the lead bending inspection apparatus of C. A ring light 2'is arranged above the FIC1 with the scattering plates 8 interposed therebetween, and on the other hand, below the FIC1 and behind the leads 5a and 5b, a camera 4a for picking up an image of the lead 5a, Cameras 4b for picking up an image of the lead 5a are arranged to face each other with their optical paths intersecting each other. The cameras 4a and 4b are related to a drive mechanism (not shown), and when inspecting FICs of different sizes, the cameras 4a and 4b can be moved left and right so that the leads 5a and 5b can be caught in the field of view of the camera. It is configured to be able to. The scattering plates 8 and 8 are for scattering the illumination light emitted from the ring light 2 ',
Due to the presence of the scattering plates 8 and 8, it is possible to irradiate the leads 5a and 5b with sufficient illumination light regardless of the size of the FIC 1. Ring light 2'and scattering plate 8,
At the center of 8, a suction cylinder 9 that is rotatable and horizontally movable is arranged. One end of the suction cylinder 9 is associated with a decompression device (not shown), and the FIC 1 can be sucked by bringing the lower end opening portion into close contact with the package 6. When the lead to be imaged is changed, the suction cylinder 9 is sucked. In the state
It is configured so that FIC1 can be rotated.

The camera 4a and the camera 4b, which are located below the package 6,
A wide-field camera 10 for positioning the package 6 is arranged substantially in the middle of the position. The camera 10 is a camera
The package 6 obtained by the camera 10 is for monitoring the position of the FIC 1 so that a silhouette image including the images of the lead tips of the leads 5a, 5b can be captured in the fields of view of the leads 4a, 4b.
The entire image of is used as a guide when controlling the movement of the cameras 4a and 4b and the suction cylinder 9. Reference numeral 11 in the figure denotes a signal processing device that processes the image information of the cameras 4a, 4b and the camera 10 and determines the quality of the FIC 1. In the figure, 12 is a supply magazine in which the pre-inspection FIC1 is stored, 13 in the figure is a storage magazine in which the post-inspection FIC1 is stored, and 14 is a transport for transferring the FIC1 from the supply magazine 12 to the position where the suction cylinder 9 exists. A device, 15 is a transfer device for transferring the FIC after the inspection to the storage magazine 13.

The operation mode of the lead bending inspection apparatus having such a configuration is as follows. First removed from supply magazine 12
The FIC1 is transferred to the lower part of the suction cylinder 9 by the transfer device 14, the lower end of the suction cylinder 9 is brought into close contact with the package 6, and the FIC1 is lifted. Next, the entire package 6 is imaged by the camera 10, the current position of the package 6 is calculated, and if the position is deviated from the predetermined position, the camera 4
The horizontal position of the a, 4b or the suction cylinder 9 is finely adjusted so that the leads 5a, 5b fit within the imaging range of the cameras 4a, 4b. In this state, the camera 4a captures the lead 5a and the camera 4b captures the silhouette image of the lead 5b at the same time, and the silhouette image is compared with a standard pattern of a non-defective product registered in the signal processing device 11 in advance. The inspection is performed at the same time. When this inspection is completed, the suction cylinder 9 is rotated 90 ° to capture the leads existing on the other two sides in the visual fields of the cameras 4a and 4b, and the inspection is performed in the same manner as described above. In this way, the silhouette image of all the leads of the FIC1 is captured and the silhouette image and the standard pattern are compared,
If even one of them has a difference from the standard pattern that exceeds the permissible value, the FIC judges that it is a defective product and discards it.On the other hand, for all leads, the difference between the silhouette image and the standard pattern is within the permissible value. If it is, the corresponding FIC is determined to be a non-defective product and is fed to the storage magazine by the transport device 15.

By the way, the leads on each side may be picked up one by one as shown in the principle diagram, but it is also possible to pick up the leads 5a, 5a ,. For example, when the images are collectively taken, a silhouette image as shown in FIG. 5A is obtained. This silhouette image is composed of the package silhouette 6'and the silhouettes 5a ', 5a' of the leads 5a, 5a, ... Of which, the silhouettes 5a ', 5a'. Only the leading edges 7b ', 7b' ... in the outer contour. Therefore, for example, image processing of the silhouette image is performed to create an image in which only the leading edges 7b ′, 7b ′ ... Are left as shown in FIG.
By comparing this image with the standard pattern of the leading edge registered in advance, the bending of the lead can be easily detected.

As described above, the present apparatus using the IC appearance inspection method according to the present invention forms the silhouette image of the lead including the images of the leading edges of the leads 5a and 5b on the image pickup device by the transmission illumination, and outlines the outline of the silhouette image. Since the lead bend is detected only by the position of the front edge of the lead, the lead bend can be detected accurately without being influenced by the state of the lead surface, and the image processing apparatus can be Since it is not necessary to recognize the entire shape of the lead as described above, it is possible to simplify. Further, in this apparatus, since the camera is arranged on the opposite side of the projecting side of the lead to be inspected with the package 6 sandwiched between them, the camera is placed facing each other as in this embodiment.
Even when using a table, it is possible to prevent light other than transmitted light from entering each other's cameras as much as possible, and it is possible to inspect the leads on each side of the package at the same time and speed up the inspection work. .

Further, according to the method of the present invention, the lead tip is imaged from an oblique direction with a small acute angle with respect to the surface in the length direction of the lead including the lead tip edge. It is possible to inspect the bending as well as the floating at the same time. Both the longitudinal direction and the float appear as a displacement in the front-back direction of the position where the lead front edge exists, and whether the cause of the displacement is the bending in the longitudinal direction or the float causes a positional relationship with the package and the package. It may not be possible to cut immediately without considering the positional relationship with the tip of the lead located on the opposite side with the pin in between, but in any case, the one with bending or floating in the lead longitudinal direction is a defective product. The defective IC can be surely checked. Further, according to the present invention, since the bending is inspected by performing the two-dimensional image recognition on the silhouette image including the image of the lead edge, the bending amount is not only detected but also the bending amount is increased. It is possible to measure with high accuracy, and by taking advantage of the characteristics of image recognition to recognize the silhouette image of the package, the positional relationship of the leads with respect to the package can also be measured. It is possible to correct the lead position even if the position is deviated from the predetermined posture, and the occurrence of inspection errors can be significantly reduced.

6 and 7 show another embodiment of the present invention. What is shown in FIG. 6 is a case where the cameras 4 are arranged so as to be offset by 90 ° and the leads existing on two adjacent sides are inspected at the same time. In this case, the angle of rotation of the FIC1 performed when changing the lead to be inspected is 180 °. Although not shown, it is also possible to arrange the cameras 4 on all sides and simultaneously image the leads on all sides. The present invention, as described above,
The method of the present invention is particularly suitable for lead inspection of a surface mounting IC having lead tips extending parallel to the upper and lower surfaces of the package, but the method of the present invention is an insertion type IC such as a DIPIC as shown in FIG. Can also be applied to. In this case, DIP type IC
Since the leads exist only on both sides of the package, it is not necessary to rotate the IC by the suction cylinder 9.

〔The invention's effect〕

The IC appearance inspection method according to the present invention is a state in which a small acute angle is made to the surface in the length direction of the lead including the lead tip edge on the side opposite to the protruding side of the lead to be inspected while sandwiching the IC package. An image pickup device for picking up an image of the tip of the lead from an oblique direction is arranged, and an illumination device is arranged behind the lead seen from the image pickup device, and an image of the lead edge is formed on the image pickup device by transmission illumination by the illumination device. The amount of bending of the lead is measured by forming a silhouette image of the lead including the image, and recognizing the image of the silhouette image using an image processing device. Therefore, the surface state of the lead is detected to detect the bending of the lead. Is no longer affected, and it becomes possible to perform highly accurate lead bending inspection. or,
Since the silhouette image is used for inspection, even if there is a bent portion in the package thickness direction in the middle of the lead, the bent portion will not appear in the silhouette image if the bending amount is small. It is not necessary to consider this, and the inspection can be rationalized. Further, the silhouette image has an advantage that the device configuration can be simplified because the outer contour can be easily grasped and is suitable for image processing.

Further, according to the present invention, since the lead tip portion is imaged obliquely with respect to the surface in the length direction of the lead including the lead tip edge, the lead longitudinal direction, the lead width direction and the floating can be inspected at the same time. For surface mounting ICs that have lead tips that extend parallel to the top and bottom surfaces of IC packages such as FICs, the lead tip float causes contact failure on the mounting board. Is extremely important, and the present invention that can inspect the bending in the lead longitudinal direction and the lead width direction as well as the floating is extremely useful.

Further, since the method of the present invention performs two-dimensional image processing on the silhouette image, it is possible to measure the accurate positions of the leading edge and the side edge of each lead, and thus simply detect whether or not the lead is bent. Not only that, the amount of bend can be measured with high accuracy. Furthermore, by using the characteristics of image recognition to recognize the silhouette image of the lead in relation to the silhouette image of the package, the position of the lead edge can be grasped in relation to the package. The position of the lead edge can be corrected even if the setting is misaligned or rotated from the predetermined posture, and the occurrence of inspection errors can be greatly reduced, and the rigor of the setting is strict. Since it is not required, the inspection can be speeded up.

[Brief description of drawings]

1 and 2 are principle diagrams of an IC appearance inspection method according to the present invention, FIG. 3 is an explanatory view showing a captured silhouette image, and FIG. 4 is a configuration using the IC appearance inspection method according to the present invention. Explanatory diagram showing the configuration of one embodiment of the lead bending inspection apparatus,
FIGS. 5 (a) and 5 (b) are explanatory views showing the captured silhouette image, and FIGS. 6 and 7 are other embodiments, FIGS. 8 and 9.
Figure, Figure 10 (a), (b), Figure 11 (a), (b),
12 and 13 (a) and (b) are explanatory views of the conventional example. 1: FIC, 2: Lighting device, 3: Imaging lens, 4: Imaging device, 4a, 4b: Camera, 5a, 5b: Lead, 5a ′, 5b ′: Silhouette, 6: Package, 6 ′: Silhouette, 7 : Lead tip surface, 7a: Top side, 7b: Bottom side, 7c: Left side, 7d: Right side, 7b ': Tip edge, 8: Scattering plate, 9: Suction tube, 10: Camera, 11: Signal processing device, 12: Supply Magazine, 13: Storage magazine, 14: Transport device, 15: Transport device, L: Illumination light, a: FIC, b: Package, c1, c2: Lead, d: End surface, e: Imaging device, f: Imaging lens , G: light source, i: lead, l: optical path, s: photodetector.

Claims (1)

[Claims] 1. A side opposite to a protruding side of a lead to be inspected with an IC package sandwiched between the IC package and a tip portion of the lead.
While arranging the imaging device at a position where an image can be picked up without being blocked by the package and a small acute angle is formed with respect to the surface in the length direction of the lead including the lead tip edge and the lead tip can be picked up from an oblique direction, An IC appearance inspection method using an apparatus in which an illuminating device is arranged behind a lead to be inspected viewed from the imaging device, wherein the imaging device includes an outline contour image of a lead tip edge by transmitted illumination by the illuminating device. A step of forming a silhouette image of the lead, and image recognition processing is performed on the obtained silhouette image to extract the pattern of the leading edge of the lead from the silhouette image, and this pattern is registered in advance. As a result of the comparison with the standard pattern of the standard pattern, the pattern of the lead tip edge obtained from the silhouette image is compared with the standard pattern. When you are displaced in the width direction it is determined that there is a bend in the width direction to the lead,
If the pattern at the tip of the lead obtained from the silhouette image is displaced in the longitudinal direction of the lead relative to the standard pattern, the process of determining that the lead length is displaced or the lead is lifted, and the pattern obtained from the silhouette image The appearance of the IC that consists of a process in which the lead tip edge pattern is judged to be a good product if the deviation from the standard pattern is within the preset allowable value, and is judged to be a defective product if it is outside the allowable value. Inspection methods.