JPH0350416B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a device for detecting defects in legs of electronic components such as IC elements, and particularly to electronic components consisting of a base and a plurality of legs aligned on both sides of the base. The present invention relates to a device for detecting bending or loss of a leg piece mainly in a direction perpendicular to the alignment direction.

<Prior art> An electronic component consisting of a base and a plurality of legs connected to both sides of the base is inserted into a plurality of holes provided in advance at corresponding locations on a circuit board, etc., and the electronic component is inserted into the circuit board. In recent years, this type of insertion work has been performed using high-speed automatic insertion devices. In this case, the mutual positional relationship of the multiple pores on the circuit board is determined in advance, so if some of the legs of the electronic component are bent, it may be difficult to insert the electronic component onto the circuit board. This may result in a final product with some electronic components missing, or
This causes inconveniences such as having to interrupt work and remove defective products from the line.

Therefore, before fixing electronic components on the circuit board,
It is necessary to check the connection state of the legs and remove from the line those legs that are too bent to be inserted into the holes on the circuit board. Conventionally, a beam of light is applied to each surface of a plurality of leg pieces, the reflected light is detected, and the image is compared with the positional relationship of the leg pieces of a normal electronic component to find out which ones match and which errors are detected. Items with a small amount that do not interfere with fixing electronic components on a circuit board were considered acceptable items, and others were removed from the line as defective items.

In order to detect bending in a direction perpendicular to the alignment direction of the leg pieces of an electronic component, a light beam is irradiated from a light source such as a floodlight installed on one side of the leg piece alignment direction, and the other side is The state of the leg is detected as a two-dimensional image by capturing the shadow of the leg with a detection unit such as an imager provided, and the condition of the leg is determined by comparing this image with an image of a normal leg. It is considered to be able to detect abnormalities.

<Problems to be Solved by the Invention> However, in this method, the light source or the detection part is aligned in the alignment direction of the leg pieces, which becomes an obstacle when transporting electronic components, and the light source or the detection part cannot be moved. In this case, it becomes difficult to speed up the process of inspecting a large number of electronic components.

Moreover, in order to capture images of the leg pieces from the direction in which the leg pieces are aligned, the leg line has a depth, so
This requires an optical system with a large depth of focus or a strictly parallel light beam from a laser beam, which is disadvantageous in that it requires multiple devices and is expensive.

<Means for Solving the Problems> In view of the drawbacks of the prior art, the main object of the present invention is to solve the problem of defective legs of an electronic component having a plurality of legs aligned along both sides of a base body. In the device for detecting the above, the light projecting means makes a light beam enter from between the rows of legs on both sides of the base substantially parallel to the bottom surface of the base and obliquely with respect to the alignment direction of the legs. , means for detecting one-dimensional images of two or more different parts in the length direction of the leg by a light beam transmitted to the outside of the leg; means for correcting the difference in size of the one-dimensional images of the leg pieces based on the geometrical relationship between the optical axis angle and the lens position, and the two or more parts from the one-dimensional image corrected by the correction means; In addition to comparing the relative positions of the legs in the leg row direction, it is determined whether or not the spacing between adjacent leg pieces in the leg row direction is within an allowable range, and the abnormality of the leg is determined. An object of the present invention is to provide a defect detection device for a leg piece of an electronic component, characterized in that it has a means for detecting.

<Operation> According to such a configuration, since the optical axis is inclined with respect to the alignment direction of the leg pieces, the light source or the detection section can be provided at a position where it does not interfere with the transport path of the electronic component. Then, the presence or absence of deformation of the leg piece is determined based on the presence or absence of a relative shift in the imaging positions of two or more parts in the length direction of the leg piece, or the shift in the interval between images of adjacent leg pieces. obtain. In addition, the difference in the size of the one-dimensional image of each leg piece that occurs depending on the distance difference is corrected based on the geometric relationship between the optical axis angle and the lens position, and then the pass/fail judgment is made. Even if pieces are discriminated based on a uniform tolerance value, there will be no difference in the tolerance rate.

Embodiments The present invention will now be described in detail with reference to specific embodiments with reference to the accompanying drawings.

FIG. 1 shows an electronic component consisting of an IC element 1 having normal legs, in which a plurality of legs 3 and 4 are provided on both sides of a molded base 2, respectively. A notch 5 for direction identification is provided at the front end of the base body 2. Conventionally, the bending of the leg piece 3 in the alignment direction of the legs 3 and 4 as shown by the arrow convenience,
Alternatively, there were problems such as requiring an optical system with a large depth of focus.

FIG. 2 is a schematic diagram showing a first embodiment of the device of the present invention.

A plurality of leg pieces 3 and 4 protrude from both left and right ends of the base body 2 having a flat rectangular cross section, and are each bent downward near the base end. IC element 1 is
It is placed so as to straddle the conveyance path 10, and is reflected at the bottom of the conveyance path 10 located between the rows of legs 3 and 4 on both the left and right sides at an angle of approximately 45° with respect to the horizontal direction. A mirror 11 is provided.

Another reflecting mirror 12 is installed diagonally below the reflecting mirror 11, and the light beam from the light source 13 is directed to the reflecting mirrors 12, 1.
1, the direction is changed to form one group of light rays pointing to the right in FIG.

A part of this group of rays is part of leg piece 4 ()
The rest of the light travels straight to the right of the leg 4, is diverted downward in FIG. 2 by the reflecting mirror 14, and is focused on the image sensor 16 by the lens 15. This line becomes a dark silhouette image only in the part where the leg piece 4 is present. sensor 1
The sensing portion 16a of No. 6 has a linear shape and captures a one-dimensional image of a portion () where the leg piece 4 intersects with a certain horizontal plane.

A pulse motor 1 having a built-in ball screw is connected to the sensor 16.
7, the sensor 16 moves left and right as shown by the imaginary line in FIG. 2, and at the same time, the sensing portion 116a also changes its position. A light beam having a different path than that before the movement is incident on the moved sensing part 16a and forms an image. This image is a one-dimensional image of the portion () of the leg piece 4 in FIG. 2 that intersects with different horizontal lines.

3 and 4 are a side view and a plan view of the embodiment of FIG. 2. The first reflecting mirror 12 has an angle of about 58 degrees with respect to the horizontal plane, and the light reflected thereon is reflected on the second reflecting mirror 11 and directed in the horizontal direction. Therefore, the light emitted from the light source 13 provided at the front side in the alignment direction and diagonally downward at the outer position of the leg row of the IC elements 1 is the first,
Its direction is changed by second reflecting mirrors 11 and 12,
Eventually, the beams will cross the leg rows with a group of rays pointing horizontally and diagonally backward.

As described above, according to the present invention, since the light rays passing through the leg array in an oblique direction are captured, the distance between the legs appears as a difference in image size in the image formed on the sensing section. That is, as shown in Fig. 5, each leg piece is an image whose size is proportional to each angle formed by the straight lines connecting the point P representing the center position of the lens and the edge of each leg piece in the alignment direction. An image is formed on the sensing section 16a. Therefore, if the leg pieces are numbered 4 ₁ to 4 ₄ in order of distance from point P, and each of the above angles is set to a ₁ to a ₄ , then a ₁ < a ₂ <
a ₃ < a ₄ . A similar relationship holds true for the intervals b ₁ to _{b 3} between the leg pieces.

Therefore, when the bright and dark images on the sensing portion 16a are scanned in correspondence with clock pulses of a certain specified frequency, two waveforms as shown in FIG. 6 are obtained, and each leg piece 4 ₁ to 4 ₄ Pulse width corresponding to A ₁ ~ _{A 4}
is proportional to the corresponding angles a ₁ to _{a 4} , and the farther the leg is from point P, the smaller the pulse width becomes with regularity. Here, since the relative positions of the second reflecting mirror 11, the IC element 1, the lens 15, and the sensing part 16a are mechanically determined, the size of the image due to the distance difference from the point P to the position of each leg piece is determined mechanically. The difference in height can be easily corrected based on the geometric relationship of each part. Such correction can be implemented by incorporating a CPU into a device that processes the output signal of the image sensor and performing arithmetic processing based on a given geometrical relationship.

The waveform diagram shown in Fig. 6 was obtained from a normal leg piece corrected by taking into account the distance of each leg piece.
The pulse timings obtained for the two positions () and () of the leg piece 4 set at intervals in the vertical direction match, and moreover, the pulse intervals are within a predetermined tolerance range.

In FIG. 7, the leg piece ₄₁ is bent inward,
The outward bending of the legs ₄₃ is detected as a timing mismatch between the pulses obtained from the two positions. In the waveform shown in FIG. 8, the timings of all the pulses corresponding to each of the legs 4 ₁ to _{4 4} match, but there are some where the intervals between adjacent pulses are not appropriate, and It can be seen that even though leg 4 ₃ is straight in the vertical direction, it protrudes more outward than the other leg pieces.

According to the present invention, it is possible to determine whether the leg is bent or missing in the medial-lateral direction, that is, in the left-right direction, but if the leg is bent in the front-back direction, that is, in the direction in which the legs are aligned, the effect You will also receive Therefore, it is possible to separately detect the bending of the leg in the front-back direction, and remove those whose bends in the front-back direction are outside the allowable range as unconditional failures, or to evaluate the influence of the bend in the front-back direction based on the geometric relationship. It is recommended that the present invention be carried out with this in mind.

By the way, if the effect of perspective difference is ignored and pass/fail judgment is made for each leg piece using a uniform tolerance value, a difference will occur in the error tolerance rate due to the difference in image size. It is conceivable to change the allowable value for each leg piece in consideration of the difference in image size, but this would inevitably complicate the judgment circuit if it were to accommodate differences in the specifications of the IC elements to be tested. Therefore, by correcting the pulse width itself in accordance with the perspective difference as described above, it becomes possible to perform pass/fail determination using one tolerance value.

FIG. 9 is a schematic diagram showing a second embodiment of the apparatus according to the present invention, in which the same members as in the first embodiment are given the same reference numerals and detailed explanations will be omitted.

The course of the light rays whose course has been changed to the right by the reflecting mirror 11 is changed downward by the reflecting mirror 18, as in the previous embodiment, and by the lens 15,
The upper part of the leg piece 4 () is attached to the sensitive part 16a of the sensor 16.
Connect the corresponding image. Next, as shown by the imaginary line, when the reflecting mirror 18 is tilted, an image corresponding to the lower part () of the leg piece 4 is formed on the sensing part 16a of the sensor 16, as in the first embodiment. . Therefore, by determining the spacing between the legs in each image and comparing the two images, it is possible to distinguish between acceptable products and defective products.

The reflecting mirror 18 in this embodiment is, for example, a so-called galvanic mirror that can be tilted by connecting a pair of upper and lower strip wires, installing magnetic pole tips with a space on both sides, and passing an electric current through the strip wires. It may be made of a structure called a mirror. Further, in the above embodiments, an incandescent lamp such as a halogen lamp is used as a light source, but any type of light source can be used.

<Effects of the Invention> According to the present invention, since transmitted light is used, the position of the leg in the left-right direction can be reliably detected as a one-dimensional image, regardless of the surface condition of the leg. . Moreover, since the detected image is one-dimensional and there is no need to use an optical system with a large depth of focus or a laser beam, the device does not become complicated and high-speed operation is possible, making it operationally and economically viable. This has a large effect, and since correction is performed to take into account the distance difference between leg segments, detection accuracy does not decrease even if all leg segments are discriminated using a uniform tolerance value, improving the yield of inspection objects. In other words, it is possible to significantly reduce the possibility of rejecting electronic components having leg bends within the allowable range.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the electronic component showing the bending of the leg pieces using imaginary lines. FIG. 2 is a schematic front view showing a first embodiment of the device according to the invention. 3 and 4 are a side view and a plan view, respectively, of essential parts of the embodiment shown in FIG. 2. FIG. 5 is an explanatory diagram showing the size relationship of corresponding leg images depending on the distance difference between the legs. 6 to 8 are waveform diagrams of signals obtained from the image sensor. FIG. 9 is a schematic front view showing a second embodiment of the device according to the invention. 1...IC element, 2...substrate, 3, 4...leg piece, 5...
Notch, 10... Conveyance path, 11, 12... Reflector, 1
3...Light source, 14...Reflector, 15...Lens, 16...
Sensor, 16a...Sensing section, 17...Pulse motor,
18...Reflector.

Claims (1)

[Scope of Claims] 1. In an apparatus for detecting a defect in a leg of an electronic component having a plurality of legs arranged along both sides of a base, a light beam is directed between rows of legs on both sides of the base. The length of the leg is determined by a light projecting means that projects light approximately parallel to the bottom surface of the base body and obliquely to the alignment direction of the leg pieces, and a light beam transmitted to the outside of the leg piece. A means for detecting one-dimensional images of two or more parts that differ in direction, and a geometric method between the optical axis angle and the lens position to detect the difference in size of the one-dimensional images of each leg that occurs depending on the perspective difference of each leg. Comparing the relative positions of the two or more parts in the leg row direction from the one-dimensional image corrected by the correcting means based on the scientific relationship, and comparing the relative positions of the two or more parts in the leg row direction, A defective detection device for a leg of an electronic component, characterized in that the device has a means for determining whether an interval in the leg row direction between the legs is within an allowable range, and detecting an abnormality in the leg. .