JPH09273919A - Illuminator for thin plate inspecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately discriminate between dull and glass platings and inspect it with one and the same light source by uniformly illuminating a thin plate product from all the direction by using a ring light source as a reflecting light source, and increasing the reflected light. SOLUTION: The reflected image and transmitted image of a thin plate 8 by a ring light source 1 and a line light source 2 are imaged by a camera 3. The formed image is converted into a digital signal by an A-D converter 14 in an image processor 15, and stored in an image gray level memory 12 via a changeover switch 9. The image of the thin plate before one processed by the processor is stored in an image gray level memory 11. The inputting and processing of the image are conducted in parallel while alternately switching the switches 9, 10 to continuously inspect it. Since the light source 1 is used as the reflecting light source, even if the plated part is gloss or dull plating, accurate inspection can be conducted without altering the illuminating angel of the light source.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Inspection of a thin plate such as a lead frame in which a given pattern such as a plating pattern to be applied is repeated at regular intervals, defect inspection 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 portion such as pattern spacing. When performing these inspections, generally, after the image is input by reflected light, the light source is switched to transmitted light and the image is input.
By performing image processing on the input images of the two patterns separately, the inspection is performed by comparing with the normal state.

However, in the case of precisely inspecting such a thin plate product in which a plurality of patterns are repeated, if the inspection is performed by the above method, the product pattern is positioned immediately below the camera for imaging, and the reflection is performed. And after switching the transmission light source and image processing of each input image separately, it is necessary to move the thin plate product and repeat the same operation to perform the inspection again.
Therefore, in order to inspect a single thin plate product, it is necessary to perform an intermittent process for each pattern, so that an efficient inspection cannot be performed.

In order to solve the above-mentioned conventional drawbacks, the inventor of the present invention simultaneously and continuously performs high-speed surface inspection and dimensional inspection of a thin plate product having a shape repeated at a plurality of pattern intervals. A thin plate inspection device that can be used in Japanese Patent Application No. 6-258871 is proposed.

[0005]

However, even if the thin plate inspection apparatus as proposed in Japanese Patent Application No. 6-258871 is used, the illumination means has the following problems. That is, in a thin plate product to be inspected, for example, a lead frame, the tips of pads and leads are generally silver-plated, and there are smooth glossy surface and rough matte plating having a rough surface depending on the surface texture.

In order to inspect the boundary of these platings, it is necessary to detect and inspect the difference between the light of the lead frame material and the reflected light of the plating surface. Fig. 1 of Japanese Patent Application No. 6-258871
The method shown in Fig. 2 is a method of illuminating a line light source as a reflection light source while inclining to illuminate the light, which causes irregular reflection due to the roughness of the plated surface, and makes it stronger than reflected light from a material having a smooth surface. Is taking. However, in gloss plating, where the surface roughness is close to that of the material surface, in order to increase the difference in reflected light, the angle of the light source is increased in the horizontal direction. I have no choice but to adopt a method to increase the brightness.
Still, it was difficult to distinguish clearly.

In addition, even if the illumination and the lens of the camera are linearly polarized with a 90 ° shift to detect the plated surface clearly, in many cases the brightness required for the camera cannot be obtained because the inclination becomes deep, Therefore, the detection tends to be unstable.

Therefore, the present invention solves the above-mentioned problems and provides a thin plate inspection apparatus capable of accurately inspecting and measuring even a thin plate product which has been subjected to both matte and gloss plating with the same light source. An object is to provide a lighting device.

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a method in which a thin plate to be inspected having a shape in which a plurality of patterns are repeatedly applied at regular intervals is continuously provided at a constant speed in a horizontal direction. A light source for reflection that irradiates the thin plate from above the thin plate, a transmissive light source that irradiates the thin plate from below the thin plate, and a light source that is provided above the thin plate. Means for picking up at least one pattern of the image of the thin plate by the reflected light and the transmitted light obtained by the irradiation from the light source, means for detecting the shading of the picked-up image and performing a digitization process, and a digitized detection result And a means for alternately storing at least one pattern for storage and comparing the stored numerical values alternately with a predetermined reference value to analyze surface defects and dimensional accuracy of the thin plate to be inspected. A lighting device as more becomes thin inspection apparatus and stage, as well as using the ring light source as reflection light source, and is characterized in illumination device in sheet inspection apparatus for using a line light source as the transmission light source.

In the present invention, by using a ring light source as a light source for reflection, a thin plate product such as a lead frame is uniformly illuminated from all directions, and by increasing the reflected light, even a glossy plated surface can be easily clarified with the material surface. Therefore, it is possible to accurately discriminate and inspect matte and glossy plating with the same light source. Also,
By applying linearly polarized light to the light source and the lens of the camera, it becomes easier to distinguish the plated surface from the material surface.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view showing an outline of a thin plate inspection apparatus and its operation of the present invention, 8 is a thin plate having a plurality of different patterns to be inspected, and 1 is a thin plate. Of the thin plate 8 obtained by the ring light source 1 and the line light source 2 is a light source for reflection 2 which is a ring light source installed above the thin plate 8 and a light source 2 for transmission which is a line light source installed below the thin plate. The reflected image and the transmitted image are respectively captured by the camera 3. 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, and the scanning time per pixel of the CCD is t,
When the transport speed of the thin plate 8 is Vw and the resolution of the image per pixel of the CCD is d, the vertical and horizontal dimension ratios of the captured images of these relationships are adjusted as follows. Vw = d / t

The image picked up by the camera 3 is converted into a digital signal by the AD converter 14 in the image processing apparatus 15, and sequentially stored in the image density memory 12 through the changeover switch 9. In addition, the image density memory 11 stores the image of the thin plate of the previous sheet which has already been captured by the camera 3, and this image is passed 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 for processing 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 10 are switched. By performing image input and processing in parallel while alternately switching, inspection by the image of the thin plate 8 can be continuously performed.

Next, a thin plate inspection method using the apparatus of the present invention will be described by taking the lead frame shown in FIG. 2 as an example.
3 is an enlarged view of the lead portion of the lead frame of FIG. 2 picked up by the apparatus of FIG. 1, where A is the lead non-plated portion, B is the lead plated portion, and C is the gap portion. Indicates. Further, FIG. 4 shows the AD converter 14 in FIG.
8 is a graph showing the brightness of each part of FIG. 3 obtained by digitizing the image captured by the camera 3 using an 8-bit converter. The value of c in FIG. 4 is a numerical representation of the brightness of the illumination of the line light source 2 in FIG. 1, and the values a and b are the numerical representation of the brightness of the illumination of the ring light source 1. . 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 gap portion C 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 excluding 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 image of the lead frame of the non-plated portion A and the plated portion B in FIG. 3 may remain. it can. By setting the reflected light from the ring light source 1 to be weak, this image can be an image that is hardly affected by the reflected light. This makes it possible to clearly capture the bright and dark portions due to the lead boundary, and the width of the lead. It is possible to make accurate measurements on distances and intervals. That is, for example, when the width and interval of the leads in FIG. 3 are measured using this image, pixel processing of the bright portion and the dark portion may be performed. In addition, when more rigor is required, the calculation is performed using a plurality of pixels near the boundary between the bright portion and the dark portion,
A method of improving the pixel resolution can also be adopted.

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 remain. Therefore, by taking a plurality of thresholds for the brightness of the remaining portions of the non-plated portion A and the plated portion B and performing pixel processing in detail for each of them, it is possible to identify surface defects and the like in these portions from the difference in brightness. It is possible to inspect the surface condition and detect the boundary between the non-plated portion A and the plated portion B. For example, among the leads 1 ′ to 3 ′ of FIG. 3, the defect portion 4 ′ occurring in the plated portion B of the lead 2 ′ and the defect portion 5 ′ occurring in the non-plated portion A of the lead 3 ′ have the same brightness. It is possible to detect the difference between the non-plated portion A and the plated portion B, and 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.

Since the ring light source 1 is used as the light source for reflection in the above processing, whether the plated portion A is glossy plating or matte plating does not change the irradiation angle of the light source. Accurate surface inspection and dimensional measurement can be performed.

[0018]

As described above, according to the illuminating device in the thin plate inspection device of the present invention, by increasing the reflected light, the boundary with the material surface can be clearly discriminated easily even on the glossy plated surface. It can be said that this invention is industrially useful because it can accurately inspect and measure even a thin plate that has been subjected to matte or gloss plating with the same light source.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an outline of a configuration of an illumination device in a thin plate inspection device of the present invention.

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

FIG. 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 in FIG. 3 obtained by digitizing an image captured by a camera using an 8-bit converter as the AD converter in FIG. 1;

[Explanation of symbols]

 1 ring light source 2 line light source 3 camera 4 driving roller 5 pressing roller 6 driving belt 7 driving motor 8 thin plate to be inspected 9 and 10 changeover switch 11 and 12 image density memory 13 image processing unit 14 AD converter 15 image processing device 16 lead frame Lead pattern 17 Surface defects A Unplated part in lead pattern B Silver plated part in lead pattern

Claims (1)

[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 irradiating the thin plate from above the thin plate. A light source for reflection, a light source for transmission which irradiates the thin plate from below to irradiate the thin plate, and a thin light plate provided above the thin plate, which is obtained by irradiation of the light source with reflected light and transmitted light. Means for picking up an image for at least one pattern, means for detecting the shading of the picked-up image to perform digitization processing, and means for alternately inputting and storing the digitized detection results for each pattern. And the stored numerical values are alternately taken out and compared with a predetermined reference value to analyze surface defects and dimensional accuracy of the thin plate to be inspected, and a lighting device of the thin plate inspection device, comprising: An illumination device in a thin plate inspection apparatus, wherein a ring light source is used as a light source for projection and a line light source is used as the light source for transmission.