JPH0894336A - Thin-plate inspection device and method - Google Patents

Abstract

PURPOSE: To simultaneously, continuously, and automatically inspect the surface and dimensions of a thin-plate product by carrying a thin plate with a plurality of different patterns at a constant speed and picking up the reflection and transmission images of the thin plate in synchronization with the carrying speed and performing image processing. CONSTITUTION: A thin-plate product 8 where a plurality of patterns are repeated with an interval are mounted on a carrier belt 6, is driven by a drive motor 7, and is carried at a constant speed. A camera 3 and a light source 1 for reflection are laid out at the upper portion of the carrier belt 6 and a light source 2 for transmission is laid out at the lower portion and the reflection and transmission images of the thin plate 8 are picked up and are inputted to an image processing device 15. A CCD camera is used for the camera 3, the scanning time per line of the CCD is set to a carrier speed of Vw, the resolution per pixel of the CCD is set to (d). Then, speed is controlled so that the carrier speed is Vx=dxt so that an aspect ration of the image which is picked up become equal. Also, the processing speed of an image processing part 13 is increased as compared with the input speed of an image to be inputted to an image light and shape memory 12, thus achieving a continuous inspection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for simultaneously measuring the surface quality and dimensional accuracy of a thin plate material having a plurality of patterns provided at a constant interval such as an IC lead frame.

[0002]

2. Description of the Related Art A thin plate such as a lead frame in which a certain pattern such as a plating pattern to be applied is repeated at regular intervals, is required to be inspected for defects such as spots and unevenness on the surface of a pattern portion. It is necessary to perform dimensional inspection of the position, width, length, etc. of the processed part such as pattern spacing, but in general, when performing these inspections, after inputting an image with reflected light, the light transmitted through the light source is transmitted. The image is input by switching to, and the input images of these two patterns are separately image-processed to compare with the normal state and the inspection is performed.

[0003]

However, in the case of precisely inspecting a thin plate product in which a plurality of such patterns are repeated, if the inspection is performed by the above-described method, the product will be directly under the camera for imaging. Pattern must be positioned, and the input images taken by switching the reflection and transmission light sources must be image-processed separately and then inspected, then the product must be moved and the same operation must be repeated again to inspect it in sequence. , To inspect a single sheet product,
Since it is necessary to perform intermittent processing for each pattern, it is not possible to perform efficient inspection.

The present invention has been made in view of the above situation, and the surface inspection and the dimension inspection of a thin plate product having a shape repeated at a plurality of pattern intervals can be simultaneously and continuously performed at high speed. It is an object of the present invention to provide such a thin plate inspection method and apparatus.

[0005]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a thin plate to be inspected having a shape in which a plurality of patterns are repeatedly applied at regular intervals, continuously in a horizontal direction at a constant speed. Means for conveying to, a reflection light source for irradiating the thin plate from above with a suitable incident angle, a transmission light source for irradiating the thin plate from below to penetrate the thin plate, and provided above the thin plate, Means for picking up an image of the thin plate for each pattern or a plurality of patterns by reflected light and transmitted light obtained by irradiation from these light sources, means for detecting the shading of the picked-up image and performing numerical processing, Means for alternately inputting and storing the detected results for each pattern or a plurality of patterns, the stored numerical values are alternately taken out and compared with a predetermined reference value, and surface defects and dimensions of the thin plate to be inspected are measured. A thin plate inspection device including means for analyzing accuracy and the like, and a thin plate to be inspected having a shape in which a plurality of patterns are repeatedly applied at predetermined intervals, and is provided above the thin plate while being conveyed in the horizontal direction at a constant speed. The reflected light and the transmitted light obtained by irradiating the thin plate to be inspected with the light source for reflection and the light source for transmission provided below the single thin film or a plurality of patterns by a camera provided directly above the thin plate to be inspected. An image is taken for each pattern, the degree of shading of the image in the picked-up image is converted into a numerical value by an AD converter, and this is alternately inputted into one image pattern or a plurality of patterns and stored in two image density memory devices, and then stored. This is taken out alternately from the memory device and compared with a predetermined reference value in the image processing section, and the surface condition and size of the pattern of the thin plate to be inspected and the pattern A sheet inspection method and performing inspection intervals simultaneously.

[0006]

Next, details of the present invention and its operation will be described with reference to the drawings.

FIG. 1 is an explanatory view showing an outline of the thin plate inspection apparatus of the present invention and its operation. Reference numeral 8 is a thin plate having a plurality of different patterns to be inspected. Reference numeral 1 is a reflection light source installed above the thin plate, and 2 is a transmission light source installed below the thin plate. The reflection image and transmission image of the thin plate 8 obtained by these light sources 1 and 2 are respectively reflected by the camera 3 Is imaged. The thin plate 8 is conveyed at a constant speed in the arrow direction by the drive roller 4 and the pressing roller 5 which are transmitted by the drive belt 6 driven by the drive motor 7.

A line CCD camera is used as the camera 3. The travel time per line of the CCD is t, the transport speed of the thin plate 8 is Vw, and the resolution of the image per pixel of the CCD is d. In this case, these relationships are adjusted as follows so that the vertical and horizontal dimensional ratios of the captured images are the same.

Vw = dt The image picked up by the camera 3 is converted into a digital signal by the AD converter 14 in the image processing device 15, and sequentially stored in the image density memory 12 through the changeover switch 9. In addition, the image density memory 11 on one side stores the image of the previous thin plate captured by the camera 3,
This image is transferred through the changeover switch 10 to the image processing unit 13
Is being processed by. In this case, if the processing speed of the image processing unit 13 that processes the image of the image density memory 11 is set to be higher than the input speed of the image input to the image density memory 12, the changeover switches 9 and 1
By performing image input and processing in parallel while alternately switching 0, inspection by the image of the thin plate 8 can be continuously performed.

Next, the thin plate inspection method according to the present invention will be described by taking the lead frame shown in FIG. 2 as an example. Figure 3
2 is an enlarged view of the lead portion of the lead frame of FIG. 2 taken by the apparatus of FIG. 1, where A is a non-plated portion of the lead, B is a plated portion of the lead, and C is a gap portion. FIG. 4 is a graph showing the brightness of each part of FIG. 3 obtained by digitizing the image captured by the camera 3 by using an 8-bit converter as the AD converter 14 in FIG. It is a thing. The value of c in FIG. 4 is a numerical representation of the brightness of the illumination of the transmissive light source 2 in FIG. 1, and a and b are the numerical representation of the brightness of the illumination of the reflective light source 1. Is. The maximum brightness of the plated portion B of the lead shown in FIG. 3 is shown by b in FIG. 4, and the brightness of the C portion is shown by c. Similarly, the maximum value of the brightness of the non-plated portion A is shown by a in FIG.

Here, the image stored in the image density memory 11 or 12 of FIG. 1 is transferred to the image processing unit 13,
By removing a portion brighter than the brightness C'which is sufficiently larger than the b value within the range from the c value to the b value in FIG. 4, the lead images of the lead frames of the A and B portions in FIG. 3 can be left. This image can be an image that is hardly affected by the reflected light by setting the reflected light from the light source 1 to be weak, which makes it possible to clearly capture the bright and dark portions due to the lead boundary, and Accurate measurements can be made of the spacing. That is, for example, by this image,
When measuring the width and interval of the lead on the alternate long and short dash line E in FIG. 3, pixel processing of the bright portion and the dark portion on the alternate long and short dashed line E may be performed. If more rigor is required,
It is also possible to adopt a method of improving the pixel resolution by using a plurality of pixels in the vicinity of the boundary between the bright portion and the dark portion to perform calculation.

Next, the non-plated portion A of the lead frame in FIG. 3 can be left by excluding the pixels between the b value and the a value in FIG. By removing the portion darker than a, the plated portion B of the lead frame can be left. Therefore, the brightness of the remaining portions A and B is set to a plurality of thresholds,
By performing pixel processing in detail for each of them, it is possible to inspect the surface condition such as surface defects in these portions and to detect the boundary between the non-plated portion A and the plated portion B from the difference in brightness. For example, the defective portion 4 occurring in the plated portion A and the defective portion 5 occurring in the non-plated portion B of the lead 2 in FIG. 3 can be detected by the difference in brightness thereof,
Also, due to the difference in brightness between the non-plated part A and the plated part B,
The boundary can be detected. The surface inspection and the dimensional accuracy measurement can be performed simultaneously by combining with the above-mentioned measurement results of the width and spacing of the leads.

[0013]

EXAMPLES Next, examples of the present invention will be described.

In FIG. 1, a lead frame in which a desired pattern is repeatedly applied by partial silver plating to a thin plate 8 to be inspected is used, and a metal halide light source of high frequency lighting is used as a reflection light source 1, and the angle is 45 degrees with respect to the thin plate 8. And the halogen light source as the light source for transmission 2 is used to illuminate the line CCD camera 3 of 1000 pixels from directly below the thin plate 8, and the image is taken by the camera 3, and the brightness of the image is shown. After adjusting the irradiation intensity of each light source so as to be as shown in FIG. 4, and setting the brightness in the range of C ′ and a to b, the pixel corresponding to the one-dot chain line E in FIG. The lead interval and the lead width of the lead frame are measured by detecting the boundary between light and dark by performing the process described in 1. and the boundary between the non-plated portion A and the plated portion B in FIG. After extracting the pixels, the threshold value of A'is measured, and for surface defects, the threshold value is set to be darker than A'when the brightness of the extracted pixels is dark and brighter than B'when the brightness is bright. It was measured.

As a result of the measurement, the maximum variation of the measured values of the lead width and the lead interval is within 2 pixels, and the variation of the measured value at the boundary between the non-plated portion and the plated portion is 4 pixels.
Since it was within pixels, dimensional inspection could be performed with extremely high accuracy. In addition, we were able to fully understand the occurrence of surface defects.

Next, the image density memory 12 shown in FIG. 1 is set to a size capable of storing an image of one lead frame, and the judgment standard of the quality of the lead frame is set by adding the maximum value of variation to the standard value. As a result of conducting the above-mentioned dimensional inspection while continuously transporting the lead frame and simultaneously inspecting the surface defects of the lead frame, it was possible to completely prevent discharge of defective products. It is needless to say that the number of image density memories 1 and the number of image processing units 13 in FIG. 1 can be a plurality of combinations depending on the number of elements of the camera 3 and the balance between the field of view and image input and processing speed. .

[0017]

As described above, according to the present invention, each lead frame has a gap portion,
In addition, it can be said that the invention is industrially useful because the dimensions of a thin plate having a plurality of repetitive patterns and surface defects can be inspected simultaneously and continuously at high speed.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an outline of a thin plate inspection apparatus of the present invention and its operation.

FIG. 2 is a plan view of a lead frame as an example of a thin plate to be inspected.

3 is an enlarged view of a lead portion of the lead frame of FIG. 2 taken by the apparatus of FIG.

4 is a graph showing the brightness of each part of FIG. 3 obtained by digitizing an image captured by a camera 3 by using an 8-bit converter as the AD converter 14 in FIG. .

[Explanation of symbols]

 1 light source for reflection 2 light source for transmission 3 camera 4 driving roller 5 holding roller 6 driving belt 7 driving motor 8 thin plate to be inspected 9 changeover switch 10 changeover switch 11 image density memory 12 image density memory 13 image processing unit 14 AD converter 15 image Processing device 16 Lead pattern of lead frame 17 Surface defect A Non-plated part of lead pattern B Silver-plated part of lead pattern

Claims (2)

[Claims] 1. A means for continuously transporting a thin plate to be inspected having a shape in which a plurality of patterns are repeatedly applied at regular intervals in a horizontal direction at a constant speed, and an appropriate incidence on the thin plate from above the thin plate. A reflection light source that irradiates at an angle, a transmission light source that irradiates the thin plate from below to penetrate the thin plate, and a reflection light and a transmission light that are provided above the thin plate and that are obtained by irradiation from these light sources. Means for picking up an image of the thin plate for at least one pattern, means for detecting the shading of the picked-up image to perform digitization processing, and inputting and storing the digitized detection results alternately for at least one pattern A thin plate inspection apparatus comprising means, means for alternately taking out the stored numerical values and comparing them with a predetermined reference value, and analyzing surface defects, dimensional accuracy, etc. of the thin plate to be inspected. 2. A thin light plate to be inspected having a shape in which a plurality of patterns are repeatedly applied at predetermined intervals is conveyed at a constant speed in the horizontal direction, and a reflection light source provided above and a reflection light source provided below the thin light plate. Reflected light and transmitted light obtained by irradiating the thin plate to be inspected from the transmitted light source,
At least one camera provided directly above the thin plate to be inspected
An image is picked up for each pattern, the degree of shading of the image in the picked-up image is digitized by an AD converter, and this is alternately input into at least two image shading memory devices for each pattern and stored therein. Alternately taken out from the memory device and compared with a predetermined reference value in the image processing unit, and simultaneously inspecting the surface condition and size of the pattern of the thin plate to be inspected and the interval for each pattern. Thin plate inspection method.