JPH02203258A - Method for inspecting solder bridge of lead component - Google Patents

Abstract

PURPOSE:To decide whether or not there is a solder bridge by setting window at positions between leads for respective images of the component, and finding the spatial differential value of brightness in the lengthwise direction of the leads as to respective images in the windows. CONSTITUTION:A controller 12 operates a lighting device 11 to light the component 11 to be inspected uniformly and an image pickup device 2 is put in operation to pick up the image of reflected light from the component 1. The image of the component 1 which is obtained by the device 2 is supplied to the device 12, which sets the window at the position between respective leads of the image; while the respective windows are scanned in the lengthwise direction of the leads in picture element units, the mean value of the brightness in each window is found at each scanning position and the difference value between the mean value of brightness at a last scanning position and the mean value of brightness at a current scanning position is found as a spatial differential value. Then the difference value of brightness is compared with a specific threshold value to check whether or not the difference value of brightness exceeds the threshold value, thereby deciding whether or not there is a solder bridge.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a solder bridge inspection method for determining whether or not a solder bridge exists between adjacent leads of a lead component having a plurality of leads. Regarding.

<Prior art> As shown in FIG. 4, this type of inspection conventionally involves uniform illumination (indicated by arrows in the figure) of lead components 1 mounted on a board.
Under this uniform illumination, the lead component 1 is captured by the imaging device 2.
This is done by taking an image.

The lead component 1 has a plurality of leads 3a to 3d lined up at equal intervals on both sides, and the tips of each lead 3a to 3d are soldered to a land portion 4 on the board.

FIG. 5 shows an image 1 of the lead component 1 obtained by the imaging device 2.
', and 3a' to 3d' in the figure represent each lead 3a to 3d.
The image is shown below. Among these leads, the leads 3a and 3d at both ends are properly soldered to the board, but the leads 3b and 3c at the intermediate position have solder spanning between them, resulting in a solder bridge 5. In addition, in Figure 5,
5' is an image of the solder bridge. Also, the xy coordinate system is
This is to indicate the position on the image.

Conventionally, to inspect the presence or absence of solder bridges 5, a window 6 is set between the images of each lead, the sum of brightness is determined for each image within each window 6, and the magnitude of the value is compared. By doing so, it is determined whether or not a solder bridge exists between adjacent leads.

Figure 6 (1) and (2) show the brightness distribution of the image along the length of the lead for each image in each window 6, and Figure 6 (1) shows the brightness distribution when there is no solder bridge. Figure (2) shows the brightness distribution when a solder bridge exists.

When a solder bridge 5 occurs between the leads 3b and 3c, the amount of reflected light on the surface of the solder bridge 5 increases, so the brightness of the image in that area increases, and the brightness distribution has a A protruding portion 7 as shown in FIG. 6 (2) appears.

In such a brightness distribution, the area of the shaded portion corresponds to the total brightness within the window 6, and a clear difference appears in the total brightness depending on whether or not a solder bridge occurs.

<Problems to be Solved by the Invention> However, according to this discrimination method, when the substrate is a white ceramic substrate, the brightness distribution of the image within the window 6 is as shown in FIG. 7 (1). The result is as shown in (2).

FIG. 7(1) shows the brightness distribution when there is no solder bridge, and FIG. 7(2) shows the brightness distribution when the solder bridge exists.

If the substrate is a white ceramic substrate, the reflection on the substrate surface will be strong, so the brightness level will be as shown in Figure 7 (1) (
As shown in 2), the overall cost is high. In the case where a solder bridge exists, the brightness distribution at the image position of the solder bridge 5 drops because the specular reflection component does not return to the imager 2 at the front and rear sloped parts 8 and 9 (see Fig. 7 (2).
), the central flat portion 10 protrudes (indicated by C in FIG. 7(2)). As a result, there is almost no difference in the total brightness within the window 6, and it is difficult to determine the presence or absence of a solder bridge by comparing the magnitude of the total.

This invention was made by focusing on the above problem, and by determining the presence or absence of solder bridges by determining the spatial differential value of the brightness of the image within the window, WEvi is made to look white like a ceramic board. It is an object of the present invention to provide a novel method for inspecting solder bridges of lead components, which can stably determine the presence or absence of solder bridges even when the presence or absence of solder bridges is present.

Means for Solving the Problems In order to achieve the above object, the present invention images a lead component having a plurality of leads under uniform illumination, and moves the image to the position between each lead. Set a window, calculate the spatial differential value of the brightness in the length direction of the leads for the image within that window, and use that value to determine whether or not a solder bridge exists between adjacent leads. ing.

Effect〉 If there is a solder bridge between the leads of the lead component,
Since the specular reflection component does not return to the camera at the inclined part of the solder bridge, but returns to the camera at other parts, there is a large difference in brightness between the two. For this reason, even for a white board such as a ceramic board, a window is set between each lead in the component image, and the spatial differential value of the brightness in the length direction of the leads is calculated for the image within that window. When determined, a noticeable difference appears in the values, so it is possible to stably determine the presence or absence of a solder bridge.

<Embodiment> FIG. 1 shows the overall configuration of a component inspection device used to carry out the solder bridge inspection method of the present invention.

In the figure, a lighting device 11 is used to uniformly illuminate the component 1 to be inspected on a substrate 15, and for example, a ring-shaped fluorescent lamp is used. The imaging device 2 is a television camera or the like, and images the reflected light from the part to be inspected 1 at a position diagonally above the part to be inspected 1.

The control device 12 inputs a video signal from the radial image device 2, performs image processing such as window setting on the image, and inspects whether or not a solder bridge 5 has occurred between adjacent leads of the component to be inspected 1. , the light projection operation of the illumination device 11 and the imaging operation of the imaging device 2 are controlled by control signals. Note that the image memory 13 stores images, and the monitor 14 is for displaying images.

FIG. 2 shows an image 1 of the inspected part l obtained by the imaging device 2.
In the figure, 3a' to 3d' represent images of leads 3a to 3d, and 5' represents an image of solder bridge 5, respectively. Among these leads, the glue at both ends is 3.
A and 3d are properly soldered to the board, but the intermediate position glued wires 3b and 3c have solder spanning between them.
Solder bridge 5 has occurred.

This solder bridge 5 includes front and rear sloped parts 8.9 and an intermediate flat part lO.
As for 9, the specular reflection component does not return to the imaging device 2, and its brightness decreases (see FIG. 7 (2)).

In order to inspect the presence or absence of this solder bridge 5, the images of each lead are inspected between 3a' and 3b', between 3b' and 3c', and between 3c'+
By setting a rectangular window 16 at each position between 3 d' and scanning each window 16 in the length direction of the lead shown by the arrow in the figure, the image in each window 16 is scanned in the length direction of the lead. We are looking for the spatial differential value of brightness.

In this embodiment, each window 16 has a vertical width of one inch of the image.
Although the width is matched to the pixel and the width corresponds to the spacing between the leads, the height and width are of course not limited to these, and the size and shape can be changed as necessary. It is.

In the case of this embodiment, in order to obtain the spatial differential value of the brightness, each window 16 is scanned pixel by pixel and the average value (or summation) of the brightness within each window 16 is determined at each scanning position. At the same time, the difference value between the average value of brightness at the previous scanning position and the average value of brightness at the current scanning position is determined as a spatial differential value.

In the above configuration, the control device 12 operates the illumination device 11 to uniformly illuminate the component 1 to be inspected, and also operates the imaging device 2 to image the reflected light from the component 1 to be inspected.

In this case, if a solder bridge 5 exists between the leads 3b and 3c of the component to be inspected 1, the specular reflection component of the light hitting the solder bridge 5 at the front and rear inclined portions 8°9 will not return to the imaging device 2. First, specular reflection components from other parts return to the imaging device 2, so even if the substrate is white like a ceramic substrate, the gap in brightness between the two will be large.

An image 1' of the inspected part 1 obtained by this imaging device 2 is given to the control device 12, and the control device 12
', and scan each window 16 pixel by pixel in the length direction of the leads. At each scanning position, calculate the average brightness value within each window 16, and The difference between the average brightness at the current scanning position and the average brightness at the current scanning position is calculated as a spatial differential value.

Figure 3 (1) shows the change in the brightness difference value when the solder bridge 5 does not exist, and Figure 3 (2) shows the change in the brightness difference value when the solder bridge 5 exists. It shows.

According to the same figure, the difference value of brightness is large at the slope part 8°9 of the solder bridge (D1 to D4 in Fig. 3 (2)).
Therefore, by comparing the brightness difference value with predetermined threshold values THI and TH2 and checking whether the brightness difference value exceeds the threshold values THI and TH2, the solder bridge is It is possible to determine whether or not it exists.

<Effects of the Invention> As described above, the present invention images a lead component having a plurality of leads under uniform illumination, sets a window at a position between each lead in the image, and displays images within the window. Find the spatial differential value of the brightness in the length direction of the lead for each image,
Based on this value, it is determined whether or not a solder bridge exists between adjacent leads, so even if the board is white like a ceramic board, it is possible to stably determine the presence or absence of a solder bridge. A remarkable effect has been achieved in achieving the purpose of the invention.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the overall configuration of a component inspection device for carrying out the solder bridge inspection method of the present invention, and FIG. 2 is an explanatory diagram showing an enlarged image of the component and the setting position of the window according to the present invention. Figure 3 is an explanatory diagram showing how the brightness difference value within the window changes, Figure 4 is an explanatory diagram showing the conventional component inspection method, and Figure 5 is an image of the component and conventional window settings. FIG. 6 is an explanatory diagram showing how the brightness changes within the window for a normal substrate, and FIG. 7 shows how the brightness changes within the window for a ceramic substrate. It is an explanatory diagram. 1...Parts 3a-3d...Lead 2.
...Imaging device 5...Solder bridge 16...
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Claims (1)

[Claims] A lead component with multiple leads is imaged under uniform illumination, a window is set between each lead in the image, and the brightness space in the length direction of the leads is calculated for each image within that window. 1. A solder bridge inspection method for lead components, characterized by determining a differential value and determining whether or not a solder bridge exists between adjacent leads based on the value.