JPH07117392B2 - Pin bend detection device in flat package - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a flat type that optically determines whether or not a foot pin is normally extended before mounting a flat package enclosing an IC on a printed circuit board or the like. The present invention relates to a device for detecting pin bending of a package.

[Conventional technology]

When mounting a flat package (1) with an IC enclosed as shown in FIG. 8 on a printed circuit board, the foot pins (2) are thin and easily bent. It is necessary to check whether ... extends normally.

The conventional inspection is performed by photographing the flat package (1) placed on the inspection table from above with a television camera or the like, and binarizing the image to recognize the pattern.

[Problems to be Solved by the Invention]

The conventional inspection method described above can detect the horizontal bending (2a) of the foot pin as shown in FIG. 9, but cannot detect the vertical bending (2b) as shown in FIG. When the flat package (1) is placed on the printed circuit board, the vertical pins are bent, so that the foot pins do not contact the bonding pads, resulting in poor soldering. Once such soldering failure occurs, the flat package (1) is assembled on the printed circuit board together with many other electronic components, and the number of foot pins is large. It takes a lot of effort and time to do
Makes the assembly cost very bad.

Therefore, an object of the present invention is to provide an apparatus capable of accurately detecting the vertical bending of the foot pin of the flat package.

[Means for Solving the Problems]

The flat package pin bending detection device provided by the present invention provides an optical system that irradiates parallel light to the foot pins of the flat package along the direction in which they are aligned, and a light flux of the parallel light that has passed near the foot pins. Cylindrical lens that shrinks in the direction of foot pin projection, a two-dimensional CCD sensor that receives light that has passed through the cylindrical lens, and the vertical bending of the pin with respect to the normal position for the binarized image stored in the second image memory The basic configuration including a determination unit for determining the presence / absence of is characterized by any one of the following configurations (1) to (4).

(1) For the binarization of the output of the above-mentioned two-dimensional CCD sensor, the first image memory for storing the image data of the inspection table without the flat package mounted by the two-dimensional CCD sensor and the flat package for the inspection table Two-dimensional CCD when placed on
The image output captured by the sensor is performed by a comparator that compares the image data stored in the first image memory pixel by pixel and binarizes the image data.

(2) Also, the presence / absence determination of the vertical bending of the pin with respect to the regular position by the determination unit and the determination of the vertical bending of the pin with respect to the regular position by the determination unit are stored in the second image memory. For the binarized image, a means for confirming the tip of the foot pin by searching from the outside along the inspection table toward the flat package, and a position of a predetermined distance l from the tip position to the root of the pin. The binarized image in is searched in order from the top, means for detecting the point where the change from bright to dark is first detected, and the length x of the change point from the upper surface of the inspection table is measured. And a means for determining whether the length is within the range of m.

(3) The binarization of the output of the two-dimensional CCD sensor in (1) and the presence / absence determination of the vertical bending of the pin in (2) are simultaneously performed.

(4) In the above basic configuration, a first mirror that bends light in a right angle direction is arranged in an optical path in an optical system, and a second mirror that bends light in a right angle direction is arranged between the cylindrical lens and the two-dimensional CCD sensor. It is assumed that the total length is shorter than the optical path length, and any one of the processes described in (1), (2), and (3) above is performed on this.

[Action]

In the above device, the shadows of the plurality of foot pins viewed from the side are incident on the two-dimensional sensor. This shadow image is reduced by the cylindrical lens in the protruding direction of the foot pin so that the entire side surface of the foot pin can be detected within the limited light receiving range of the two-dimensional sensor. Since the up and down direction of the foot pin is not reduced, the up and down bending of the foot pin, which is the detection target of this device, can be detected with high accuracy. In the binarized image of the foot pin obtained by the two-dimensional sensor, the presence or absence of bending is determined by the magnitude of the deviation from the regular position.

Further, by using the first mirror and the second mirror, the total length can be shortened and the device can be manufactured compactly.

In particular, the binarization of the output of the two-dimensional CCD sensor is performed based on the imaging data of the inspection table without the flat package, so that the light and dark variations due to light diffraction etc. It is possible to improve the detection accuracy by eliminating the influence of (having a difference).

In addition, it is determined whether or not the pin bends in the up-down direction, the tip of the foot pin is confirmed with respect to the binarized image, and the binarized image is obtained at a position of a predetermined distance l from this tip position toward the root of the pin. Are sequentially viewed from the top, and the length x from the upper surface of the inspection table at the point where the light first changes from light to dark is within the range of the predetermined length m. Judgment becomes possible and the judgment time can be shortened.

〔Example〕

FIG. 1 shows one unit of the detection unit of the detection device according to the present invention. In FIG. 1, (3) is an optical system for irradiating parallel light, for example, a pinhole is arranged in front of the high-power LED (4) to form a point light source, and this is directed at a right angle by a first mirror (5). It is bent and collimated by the lens (6).
(7) is the first slit and limits the irradiation range of the parallel light.
(1) is a flat package which is the object to be inspected placed on the inspection table (B), and the four sides (or two sides) around it are parallel to the foot pins (2) ... As shown in FIG. Have been extended to. The flat package (1) is arranged so that parallel light is emitted from the side of the foot pins (2) ... And passes along the direction of arrangement. (8) is a second slit that limits the light receiving range and reduces the incidence of external light. (9) is a cylindrical lens, a foot pin (2) ...
The luminous flux of parallel light that has passed through the vicinity is reduced in the protruding direction of the foot pin. (10) is a second mirror which bends the light emitted from the cylindrical lens (9) at a right angle. (11) is a two-dimensional CCD
In the sensor, pixels are arranged vertically and horizontally in an array of, for example, 492 × 512 bits.

When detecting the flat package (1) having foot pins in four directions, the detection unit (12) is assembled with four sets in a rectangular frame-shaped case (13) as shown in FIG. . As the case (13), for example, the case shown in FIGS. 3 (a) and 3 (b) is used. In Fig. 3 (a) and (b), (7)
Is a first slit, (8) is a second slit, (14) ... Is a light-shielding plate for preventing light interference between the detection parts, (15) ... Mounting bolt insertion holes, (16) and (17) are It is an input / output connector. In this case (13), a CCD drive circuit is built in in addition to the four sets of detectors (12) ... And the output of the two-dimensional CCD sensor is output as a video signal.

FIG. 4 shows a judging means (18) for processing the video signal output from the detecting section (12).

In FIG. 4, (19) is an A / D converter for converting a video signal into a digital signal, (20) is a first image memory, and four sets of the inspection table B in which the flat package (1) is not mounted are photographed. Image data (hereinafter referred to as original image) is stored respectively. (21) is a D / A converter, and the first image memory (2
0) ... Stored data is converted to analog. (22) is a variable resistor for adjusting the binarization level, and (23) is a comparator, which compares the image data when the original image and the flat package are placed on the inspection table pixel by pixel and performs the binarization process.
(24) is a second image memory for storing a binarized image of four screens. (25) is an image control circuit for generating a clock signal, horizontal and vertical synchronization signals, etc.
The data is output to the CCD drive circuit and the second image memory (24), and the timing for reading and writing the image data is set. (26)
Is the original image captured in the first image memory (20) by the NTSC conversion circuit, the image data output from the detection unit (12), and the binarized image that has been binarized and stored in the second image memory (24) Is selectively converted to an NTSC signal and output to a monitor TV.

Reference numeral (27) denotes a CPU, which performs predetermined arithmetic processing on the binarized image stored in the second image memory (24) to determine whether or not the foot pin of the flat package is bent. (28)
RAM is used as a work area for the CPU and is backed up by a battery (29).

(30) is an input / output circuit, which outputs the judgment result by the CPU (27) and inputs commands such as inspection start and original image display. (3
1) is a key display circuit, which controls the input key (32) and the display of input data on the numeric display (33).

(34) is a cursor circuit, which displays the judgment position on the monitor screen with the cursor when the judgment position data is input.

The operation of the pin bending detection device of the flat package will be described below.

First, in the empty state in which the flat package is not placed on the inspection table (B), the original images for four screens are loaded from the detection unit (12) into the first image memory (20) as the reference level for the binarization process. Due to the influence of diffraction and the like, this original image has a difference in brightness and darkness even in the same shadow part due to the position of the pixel of the two-dimensional CCD sensor.

Next, place the flat package (1) on the inspection table (B),
At this time, the image data obtained from each detector (12) is compared with the original image stored in the first image memory (20) described below by the comparator (23) for each pixel, and binarized. The output level of the original image is reduced to 1/3 to 1/4 by the variable resistor (22). The binarization method for comparing with the original image eliminates the influence of variations in brightness and darkness of the original image due to light diffraction, etc., so that the foot pins (2) of the flat package (1) can be seen from the lateral direction. A binarized image can be obtained with high accuracy. This binarized image is stored in the second image memory (24).

Upon completion of the binary processing, the CPU (27) determines whether or not the foot pins (2) ... Bend in the vertical direction. The procedure of this arithmetic processing is performed as follows, for example.

First, as shown in FIG. 5, a position 0.09 mm above the inspection table (B) is searched from the outside toward the flat package (1) while determining whether or not each pixel is a shadow. This search is performed by the CPU (27) with respect to the stored contents of the second pixel memory (24). When a shadow is first detected, it is determined that it is the tip of the foot pin (2) because the shadow continues for a predetermined number of bits. When this determination is made, the position at the distance l is searched inward in the vertical direction from this tip position. This searches the binarized image in order from the top, and first detects the point where the darkness changes from bright to dark. This change point is also determined by the continuation of several bits.

Then, the length x from the upper surface of the inspection table (B) at this change point is measured, and whether the length x is within the range of the predetermined length m is determined to be good or bad. According to this determination method, x <m is normal in the normal case shown in FIG. 6 and normal, and x is the normal case when the foot pins (2) are bent as shown in FIG. > M, which is a defect. This determination signal is output through the input / output unit (30), the good flat package (1) is mounted on the printed circuit board as it is, and the defective flat package (1) is sorted as a defective product separately. After correcting the bend of ..., it is supplied to the mounting line again. The predetermined lengths l and m are appropriately set according to the length and thickness of the foot pins (2) ... Of the flat package (1) to be inspected by using the input key (32) shown in FIG. Done.

〔The invention's effect〕

According to the present invention, it is possible to accurately detect the vertical bending of the foot pin of the flat package, and it is possible to improve the yield of the mounting process of the flat package on the printed board.

Especially, by using a cylindrical lens, the shadow is reduced in the protruding direction of the foot pin, which does not require so much accuracy, so the two-dimensional CCD sensor with a high detection accuracy maintains the entire image near the foot pin with a high detection accuracy. It can be made incident, and the sensor can be made small and at low cost.

In particular, the present invention binarizes the image data of the inspection table in which the flat package is not placed as a reference, confirms the tip of the foot pin, and then uses this as a reference to determine the vertical bending of the pin. Since it is performed, highly accurate determination can be performed in a short time.

[Brief description of drawings]

FIG. 1 is a schematic view showing a detection unit of a flat package pin bending detection device of the present invention, and FIG. 2 shows four sets of detection units as a case for detecting a flat package having four-direction foot pins. FIG. 3 (a) and FIG. 3 (b) show a specific example of the case shown in FIG. 2, FIG. 3 (a) is a plan view, and FIG. 3 (b) is a cross section taken along line AA. It is a figure. FIG. 4 is a block diagram of the determination means of the pin bend detecting device of the flat package of the present invention, and FIG. 5 is a diagram showing the determination points for explaining the determination procedure performed on the binary image of the shadow of the foot pin. FIG. 6 is a side view of a flat package having a normal foot pin, and FIG. 7 is a side view of a flat package having a bent pin. FIG. 8 is a perspective view showing an example of a flat package, and FIG.
FIG. 10 is a plan view of a flat package in which the foot pin has a horizontal bend, and FIG. 10 is a side view of a flat package in which the foot pin has a vertical bend. (1) …… Flat package, (2) …… Foot pin, (3) …… Optical system, (5) …… First mirror, (9) …… Cylindrical lens, (10) …… Second mirror, (11) …… two-dimensional CCD sensor, (12) …… detector, (18) …… determination means.

Claims (4)

[Claims] 1. The parallel light is applied to the foot pin of the flat package,
An optical system that illuminates along the alignment direction, a cylindrical lens that reduces the light flux of the parallel light that has passed near the foot pin in the foot pin protruding direction, and a two-dimensional CCD sensor that receives light that has passed through the cylindrical lens, In a pin bending detection device of a flat package, which comprises a determination means for binarizing the output of the two-dimensional CCD sensor and determining whether the pin vertically bends with respect to the normal position, the two-dimensional CCD sensor output The value was imaged with the first image memory that stores the image data of the inspection table without the flat package placed on it with the two-dimensional CCD sensor, and with the two-dimensional CCD sensor when the flat package was placed on the inspection table. The image output is performed by a comparator that compares each pixel with the image data stored in the first image memory and binarizes the image data. Pin bending of the detection device of the flat package to. 2. Collimated light is applied to the foot pin of the flat package,
An optical system that illuminates along the arrangement direction, a cylindrical lens that reduces the light flux of the parallel light that has passed through the vicinity of the foot pin in the foot pin protruding direction, and a two-dimensional CCD sensor that receives light that has passed through the cylindrical lens, A flat package pin bending detection device comprising a determination means for binarizing the output of a two-dimensional CCD sensor and determining whether or not the pin is vertically bent with respect to the regular position. The presence or absence of bending in the vertical direction of the foot is determined by searching the binary image from the outside along the inspection table toward the flat package and confirming the tip of the foot pin, and from the tip position to the root of the pin. A predetermined distance l
Means for searching the binarized image at the position of from the top in order and detecting the point where the change from bright to dark first, means for measuring the length x of the change point from the upper surface of the inspection table, and the length. A device for detecting pin bending of a flat package, characterized in that it is performed by means for judging whether or not the length x is within a range of a predetermined length m. 3. Parallel light is applied to the foot pins of the flat package,
An optical system that illuminates along the arrangement direction, a cylindrical lens that reduces the light flux of the parallel light that has passed through the vicinity of the foot pin in the foot pin protruding direction, and a two-dimensional CCD sensor that receives light that has passed through the cylindrical lens, In a pin bending detection device of a flat package, which comprises a determination means for binarizing the output of the two-dimensional CCD sensor and determining whether the pin vertically bends with respect to the normal position, the two-dimensional CCD sensor output The value was imaged with the first image memory that stores the image data of the inspection table without the flat package placed on it with the two-dimensional CCD sensor, and with the two-dimensional CCD sensor when the flat package was placed on the inspection table. A comparator for comparing the image output with the image data stored in the first image memory, pixel by pixel, and storing it in the second image memory. The presence / absence of the vertical bending of the pin with respect to the regular position in the determination means is determined by searching the binary image from the outside along the inspection table toward the flat package and determining the tip of the foot pin. A means for checking and a predetermined distance l from the tip position toward the root of the pin.
Means for searching the binarized image at the position of from the top in order and detecting the point where the change from bright to dark first, means for measuring the length x of the change point from the upper surface of the inspection table, and the length. A device for detecting pin bending of a flat package, characterized in that it is performed by means for judging whether or not the length x is within a range of a predetermined length m. 4. A first mirror, which bends light in a direction perpendicular to an optical path in the optical system, the cylindrical lens, and the two-dimensional structure.
A second mirror for bending the light in a direction perpendicular to each other is arranged between the CCD sensors so that the total length is shorter than the optical path length.
The pin bending detection device of the flat package described in any one of 1.