JP2726603B2 - Inspection area correction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection area correction method for correcting an inspection area.

[0002]

2. Description of the Related Art When inspecting a soldered portion of an electronic component mounted on a printed circuit board by an inspection device, a field image viewed from an inspection camera is shifted due to warpage of the unevenness of the printed circuit board. You may not be able to do it.

[0005] For example, as shown in FIG. 5, an image viewed from a top camera 21 disposed right above a substrate is distorted by expansion and contraction due to unevenness of the substrate. In addition, PLC
When inspecting a C or SOJ type IC lead, it is not possible to inspect the IC lead from directly above due to the structure of the component. When the side camera 22 is used, in addition to the enlargement / shrinkage of the image due to the unevenness of the substrate, a phenomenon in which the position of the inspection area shifts up and down appears, and the inspection may not be satisfactory.

More specifically, FIGS. 5 (b) and 5 (d) are examples of images of an SOP component (surface mounted component) viewed from a side camera 22. There is no case, and the latter is a case where the substrate is lifted.
FIG. 5 will be briefly described below.

FIG. 5A shows a case where the substrate is at a reference position without distortion of the substrate. When the substrate at this reference position is photographed by the side camera 22 with an IC lead, an image as shown in FIG. 5B is obtained. The hatched portion is a predetermined inspection area, and the quality of the soldering is determined. The IC lead to be entered is here.

On the other hand, FIG. 5C shows a case where the substrate is unevenly distorted and is floating from a reference position. When the substrate floating from this reference position is photographed with an IC lead by the side camera 22, an image as shown in FIG.
The portion to be inspected is located at a position distant from the predetermined inspection area, and the IC lead for judging the quality of soldering is not inserted, so that the inspection cannot be performed.

For this reason, the following method has conventionally been adopted in order to avoid a phenomenon in which the inspection area is displaced during photographing by the side camera 22 due to unevenness of the substrate.

(1) The substrate is evacuated from below to prevent the substrate from floating. As described above, the lifting of the substrate is suppressed by the vacuum suction, so that the image of the inspection area is not shifted when photographed by the side camera 22.

(2) The distortion of the substrate is kept within a certain range. This improves the soldering process (flow, reflow), and suppresses the distortion of the substrate so as not to distort it.

[0010]

According to the above-mentioned method (1), the lifting of the substrate is suppressed by vacuum suction.
Even if an image is obtained by photographing the inspection area with the side camera 22, there is no deviation. However, every time the model of the substrate to be inspected is changed, the position of the suction pad must be manually changed in accordance with the shape of the substrate, resulting in a problem that the operation is troublesome.

According to the above-mentioned method (2), it is necessary to improve the soldering process and the like so that the substrate itself is not distorted so that it does not float from the reference position. And lacks practicality.

The present invention has been developed to solve these problems.
From the image taken by the top camera, the size of the components on the board is measured to determine the board floating amount ΔL, and based on this, the inspection area on the image taken by the side camera is corrected, and the board floating The purpose is to seek the correct inspection area even if it exists.

[0013]

Means for solving the problem will be described with reference to FIG. In FIG. 1, a top camera 1 is a camera provided directly above, which photographs a component arranged on a substrate 3.

The side camera 2 is a camera provided on a side surface for photographing a component arranged on the substrate 3. The inspection area correction processing 6 is performed on the substrate 3 captured by the top camera 1.
Based on the size of the upper part, the inspection area of the part on the image photographed by the side camera 2 is corrected.

[0015]

According to the present invention, as shown in FIG. 1, a top camera 1 and a side camera 2 are arranged directly above a substrate 3 and side surfaces thereof.
Inspection area correction processing 6 corrects the inspection area of the component on the image captured by the side camera 2 based on the size of the component on the board 3 captured by the top camera 1, and the corrected inspection area Inspection is performed.

At this time, the inspection area correction processing 6 obtains the board floating amount ΔL from the reference position of the board 3 based on the size of the parts on the board 3 photographed by the top camera 1,
The correction amount ΔY of the inspection area of the component on the image captured by the side camera 2 is calculated from the board floating amount ΔL, and the correction of the inspection area of the component on the image captured by the side camera 2 is performed by the correction amount ΔY. The inspection is performed on the inspection area after the correction.

Further, in the direction perpendicular to the corrected inspection area, a correction (enlargement or reduction correction) corresponding to the substrate floating amount ΔL is further performed. Therefore, the size of components on the board 3 is measured from the image taken by the top camera 1 to obtain the board floating amount ΔL, and based on this, the inspection area on the image taken by the side camera 2 is corrected. This makes it possible to find the correct inspection area and perform the inspection even when the substrate is lifted when the inspection is performed using the side camera 2.

[0018]

Next, the structure and operation of an embodiment of the present invention will be sequentially described in detail with reference to FIGS.

FIG. 1 is a block diagram showing one embodiment of the present invention.
In FIG. 1, a top camera 1 is a camera provided directly above for photographing a component arranged on a substrate 3, and is arranged on a moving mechanism movable in the X and Y directions.

The side camera 2 is a camera provided on a side surface for photographing a component placed on the substrate 3.
It is arranged on a table, and is arranged on a moving mechanism that can move in the X direction and the Y direction.

The board 3 is a printed board or the like, and is a board to be inspected on which components are arranged and soldered.
The image memory 4 includes the top camera 1 and the side camera 2
The image of the component of the board 3 captured by the above is stored.

The MPU 5 performs various processes in accordance with a program.
And arithmetic processing 7 and the like. The inspection area correction processing 6 corrects the inspection area of the component on the image captured by the side camera 2 based on the size of the component on the board 3 captured by the top camera 1 (from FIG. 2). This will be described later with reference to FIG. 4).

The arithmetic processing 7 carries out various arithmetic processing (see FIGS. 2 to 4). Next, the operation of the configuration of FIG. 1 will be described in detail according to the order shown in the flowchart of FIG.

In FIG. 2, in step S1, an image is captured by a top camera. In this case, an image of a component mounted on the substrate 3 is captured by the top camera 1 disposed directly above the substrate 3 in FIG. For example, FIG.
(A) is stored in the image memory 4.

In step S2, the distance between the leads at both ends is measured.
This is based on the image W captured in S1, for example, the IC lead image shown in FIG.
The distance W2 between both ends of the lead described as 2 is measured.

S3 is substituted into the equation (2) to calculate the substrate floating amount Δ
Calculate L. This is obtained by calculating the distance W2 between both ends of the lead measured in S2 and the actual distance W1 between both ends of the lead of the component taken out from the component library in Expression (2) described later.
To calculate the substrate floating amount ΔL.

In step S4, the correction value ΔY is calculated by substituting the correction value into the equation (3). That is, the correction amount ΔY of the inspection area of the component is calculated by substituting the board lift amount ΔL obtained in S3 into the expression (3) described later.

In step S5, the interval P of the inspection area is obtained from the equation (4).
Is calculated. In this case, the distance P between the inspection areas is calculated by substituting the distance W2 measured in S2, the ΔL calculated in S3, the number of leads N taken out from the component library, and the like into Expression (4) described later. As a result, the enlargement / reduction correction in the direction perpendicular to the inspection area is performed in accordance with the substrate floating amount ΔL.

In step S6, the original inspection area is moved in the vertical direction by ΔY, and is corrected by P in the horizontal direction. This is because the substrate 3
Corresponding to the substrate floating amount ΔL, the correction is performed by the correction value ΔY in the vertical direction when the image is taken by the side camera 2 and the correction is performed at the interval P between the inspection areas in the perpendicular direction. Thus, the inspection area is corrected to the correct inspection area when the image is captured by the side camera 2.

In step S7, an area to be inspected is cut out and inspected. In this case, an image is cut out from a correct inspection area corrected in accordance with the floating amount of the substrate 3 when photographed by the side camera 2 corrected in S6, and for example, it is inspected whether the soldering of the lead is performed normally.

As described above, the size of the components on the board 3 is measured from the image taken by the top camera 1, and the board floating amount ΔL from the reference position is obtained (obtained by substituting into the equation (2)). The correction value ΔY of the inspection area when the photograph was taken in step 2 is obtained (determined by substituting into the equation (3)), further, the interval P in the direction perpendicular to the inspection area is determined (substituted by the equation (4)), and the side The original inspection area of the camera 2 is moved in the vertical direction by ΔY and corrected by P in the horizontal direction. Thus, the inspection area when the component on the board 3 is photographed by the side camera 2 is corrected, and an image is cut out from the corrected inspection area to determine the quality of the soldering.

FIG. 3 is a diagram (part 1) for explaining the operation of the present invention. This means that the top camera 1 shown in FIG. 1 captures an image of a component on the board 3, measures the distance W 2,
FIG. 9 is an explanatory diagram when calculating. This will be described sequentially below.

[1] Measurement of distance W2: FIG. 3A shows an example of an image of a component on the substrate 3 taken by the top camera 1. FIG. Here, an image obtained by photographing the IC on the substrate 3 by the top camera 1 is stored in the image memory 4, and the distance W2 shown at both ends of the IC lead is measured on this image.

[2] Calculation of actual IC lead distance W1: The actual distance W1 between both ends of the IC lead is calculated from the lead pitch data of the components registered in advance in a component library or the like. The relationship between the actual distance W1 and the distance W2 measured in [1] is expressed by the following equation (1) (see FIG. 3B).

[0035] Lb: distance from camera lens center to substrate surface (focal length) Ls: shoulder height of IC lead ΔL: substrate floating amount (positive number: floating, negative number: sinking) Here, lens includes Ls and ΔL It is assumed that the focus has been narrowed down to the specified depth of focus.

[3] Calculation of substrate floating amount ΔL: The substrate floating amount ΔL can be calculated by the following equation (2) by modifying the equation (1). FIG. 4 shows an operation explanatory diagram (part 2) of the present invention. This is an explanatory diagram when a part on the board 3 is photographed by the side camera 2 in FIG. 1 and the inspection area is corrected. This will be described sequentially below.

[4] Calculation of the correction value ΔY of the inspection area on the image of the side camera 2: FIG. 4C shows an example of an image obtained by photographing a component on the board 3 by the side camera 2. Here, an image obtained by photographing the IC on the substrate 3 by the side camera 2 is stored in the image memory 4, and the correction value ΔY of the inspection area is calculated on this image. The correction value ΔY of the position of the inspection area in the image (side camera) is calculated by the following equation (3).

[0038] ΔYs = ΔL × cos θ sin θ: Mounting angle θ of side camera 2 (directly below is assumed to be 0 °) ΔY: Correction is upward of screen when negative number Kt: Magnification of image of top camera 1 Ks: Image of side camera 2 [5] Calculation of inspection area interval P: The inspection area interval P on the image from the side camera 2 due to substrate distortion is calculated by the following equation (4). The position of the inspection area corrected in the vertical direction in [4] is further corrected in the horizontal direction (the pitch direction of the IC leads) by the interval P calculated by the equation (4). At this time, the position of the inspection area closest to the center in the horizontal direction on the screen is set as the center reference, and the horizontal position of the inspection area is allocated and corrected by multiplying by the area interval P as the distance from the inspection area increases in the pitch direction.

[0039] N: Number of IC leads arranged in series in the screen Top camera 1 when side camera 2 is not used
Is only the enlargement / reduction distortion of the image, and only the pitch is corrected by the following equation (5). At this time, the position of the inspection area closest to the center of the screen in the horizontal direction is set as the center reference, and the horizontal position of the inspection area is assigned by multiplying by the area interval P as the distance from the inspection area increases in the pitch direction,
to correct.

[0040] FIG. 3 shows an operation explanatory diagram (part 1) of the present invention. This is an explanatory diagram of an image obtained by the top camera 1.

FIG. 3A shows an example of an image obtained by photographing a component on the substrate 3 by the top camera 1. Here, the distance W2 is a value obtained by measuring the distance of an IC lead pin as a component on an image.

FIG. 3B shows the relationship among the screen position (fixed), the lens position (fixed), and the substrate position of the top camera 1. Here, W2: the measured distance W2 on the image in FIG. 3A W2 W1: the actual distance W1 extracted from the parts library Wb Lb: the distance from the camera lens center to the substrate surface Lb ': from the screen position to the lens center ΔL: board floating amount Ls: shoulder height of IC lead FIG. 4 is a diagram (part 2) illustrating the operation of the present invention. This is an explanatory diagram of an image obtained by the side camera 2.

FIG. 4C shows an example of an image obtained by photographing a component on the board 3 by the side camera 2. Here, the correction value ΔY is a correction value from the inspection area position when the substrate lifting amount is “0”.

FIG. 4D shows the relationship between the floating amount of the board and the like and the side camera 2. Here, ΔL: board floating amount ΔY: inspection area correction value as viewed from side camera 2 when board floating amount ΔL θ: angle of axis of side camera 2 with respect to axis of top camera 1

[0045]

As described above, according to the present invention,
A configuration in which the size of components on the board 3 is measured from an image taken by the top camera 1 to determine the board floating amount ΔL, and based on this, the inspection area on the image taken by the side camera 2 is corrected. Since the inspection is performed using the side camera 2, even if the substrate 3 is lifted, a correct inspection area can be obtained and the inspection can be performed. Accordingly, when the inspection cannot be performed by the image from directly above the substrate 3, the inspection area on the image from the side camera 2 can be corrected based on the image from the top camera 2, and the inspection can be performed. It is particularly convenient when performing an appearance inspection of soldering.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of one embodiment of the present invention.

FIG. 2 is a flowchart illustrating the operation of the present invention.

FIG. 3 is an operation explanatory diagram (part 1) of the present invention.

FIG. 4 is a diagram (part 2) illustrating the operation of the present invention.

FIG. 5 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 1: Top camera 2: Side camera 3: Substrate 4: Image memory 5: MPU 6: Inspection area correction processing 7: Calculation processing

Claims (3)

(57) [Claims] An inspection area correcting method for correcting an inspection area, comprising: a top camera (1) provided directly above and a side camera (2) provided on a side surface for photographing a component arranged on a substrate (3). Based on the size of the component on the board (3) photographed by the top camera (1), the position correction and the position correction of the inspection area of the component on the image photographed by the side camera (2) in real time. To expand at right angles
An inspection area correction process (6) for performing large or reduction correction is performed, and an inspection is performed on an inspection area corrected by the inspection area correction process (6) from an image captured by the side camera (2). An inspection area correction method characterized by comprising: 2. A board floating amount ΔL from a reference position of the board (3) is obtained based on the size of components on the board (3) photographed by the top camera (1). The inspection area correction method according to claim 1, further comprising an inspection area correction process (6) for calculating a correction amount ΔY of an inspection area of the part on an image captured by the side camera (2). 3. An enlargement or reduction correction corresponding to the substrate lifting amount ΔY in a direction perpendicular to the correction amount ΔY of the position of the inspection area corrected according to claim 1 or 2. Inspection area correction method to be performed.