JPH0287004A - Apparatus for measuring pattern width of printed wiring board - Google Patents

Abstract

PURPOSE:To accurately measure a pattern width by calculating the center of a through-hole and the min. radius between said center and the outside of the annular pattern in contact with the outside of said through-hole and subtracting the radius of the through-hole from the min. radius. CONSTITUTION:The image signal of a substrate 13 is inputted to the A/D converter 16 of an image processor 15 as an analogue signal from an image sensor 14 to output a multivalent image 17. This multivalent image 17 is processed at a certain threshold level by a binarization processing part 18 and a binary image 19 wherein an annular pattern is set to a white image and other part is set to a black image is outputted to a pattern width measuring and processing part 20 to measure a pattern width. The center of a through-hole and the min. radius between said center and the outside of the annular pattern in contact with the outside of said through-hole are calculated by the processing part 20 and the radius of the through-hole is subtracted from the min. radius to measure the min. pattern width.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a pattern width measuring device for printed wiring boards.

(Prior Art) Some devices that measure the pattern width of a conventional printed wiring board (hereinafter referred to as a board) by image processing include an annular pattern between a through hole 1 and a pattern 2 on a resist 1, which results in a black image as shown in FIG. In order to measure the minimum width 4 of 3, there is a method that expands a black image or contracts a white image and measures the number of pixels processed until through hole 1 and pattern 2 are connected.

(Problem to be Solved by the Invention) However, as shown in FIGS. 5(a) to (d), even if the pattern width is 4, the number of pixels is 6 at the angle of the input image, for example in FIG. Since there are 8 pixels in (b), the pattern width cannot be accurately measured using the conventional simple expansion and contraction process.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a pattern width measuring device for printed wiring boards that can accurately measure pattern widths.

[Structure of the invention]

(Means and Effects for Solving the Problems) The present invention provides a button width measuring device for a printed wiring board that processes an image signal of a pattern on a printed wiring board to measure the width of the pattern. By providing a pattern width measurement unit that calculates the minimum radius between the center of the image line and the outer image line of the pattern outside this center and subtracts the radius of the through hole from this minimum radius, the pattern can be accurately measured regardless of the orientation of the imaged pattern. This is a printed wiring board pattern width measuring device that can measure the width.

(Example) Hereinafter, an example of the pattern width measuring device for a printed wiring board according to the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of the device on the pattern width side of the substrate according to the present invention, in which the image signal of the substrate 13 is outputted as an analog signal from the image sensor 14 to the A/F of the image processing device 15.
It is input to the D converter 16 and outputs a multivalued image 17. This multivalued image 17 is processed at a threshold level by a binarization processing unit 18, and the annular pattern 3 is made into a white image and the others are made into a black image. The resulting binary image 19 is output to the pattern width measurement processing section 20, and the pattern width is measured.

Figure 2(a) shows the extracted binary image 1 of the through-hole area.
9, the shaded area becomes a white image showing the annular pattern 3, and the inner circular part becomes a black image showing the through hole 1.

Next, how to determine the center coordinates and radius of the through hole 1 for pattern width measurement will be explained with reference to FIG. 2(b).

First, draw a straight line A that crosses the through hole 1, set the intersection of this straight line A and the outer periphery of the through hole 1 (that is, the boundary between the black image and the white image) as ax+az, and draw a line a□.

The center of a2 is a. shall be. Next, this a. , draw a straight line B perpendicular to line A, let the intersection with the outer periphery of through hole 1 be b2, and draw line b1. Find the midpoint of b. shall be. Here a. +bo is the center coordinate of through hole 1.

Also, the radius r of the through hole 1 is r:b1b2 becomes.

Next, the center coordinate a of the through hole 1 is thus determined. After determining l bn and radius r, the method for measuring the minimum width 4 is shown in Figure 2 (
C) and FIG. 3.

First, turn it on. Find a set 6 of circumferential pixels with a certain radius Ω from Ω, and check whether all pixels are white. If all pixels are white, Q
Check with a new radius of 10ΔQ=Q□, and if black is mixed in, check whether all pixels are white with a new radius of Q−ΔQ. By repeating this procedure, the maximum radius j(max) of the white image is determined.

Then, the minimum width 4 can be determined by Qmax - r.

Furthermore, when checking whether the minimum width 4 is greater than or equal to a certain tolerance value (m), the set 6 of circumferential pixels is set as the radius Q=m+r.
All you have to do is find out whether the pixels on the entire surface are white or not. If all the pixels are solid, it is determined to be good, and if black is mixed in, it is determined to be defective.

In the above embodiment, after converting to a binary image at a certain threshold level (see Figure 1), the center coordinates (ao+bo)
The minimum width 4 was calculated by determining the radius r, but instead of converting the image to a binary image, instead of determining black and white for the binary image, the threshold level and the threshold level for the multi-value image were determined. By determining the height, the minimum width 4 may be calculated by determining the center coordinates (an 1bo) and radius r in the same manner as the method described in FIGS. 2 and 3.

〔Effect of the invention〕

As described above, according to the present invention, in the pattern width measuring device for a printed wiring board that measures the width of the pattern by processing the image signal from the image input unit that captures the image of the pattern on the printed wiring board,
The above image processing device is equipped with a processing unit that calculates the minimum radius between the center of the through hole and the outside of the annular pattern that touches the outside from this center, and subtracts the radius of the through hole from this minimum radius to measure the minimum pattern width. Therefore, it is possible to obtain a pattern width measuring device for a printed wiring board that can accurately measure the pattern width regardless of the orientation of the printed wiring board imaged.

[Brief Description of the Drawings] Fig. 1 is a block diagram showing an embodiment of the printed wiring board pattern width measuring device of the present invention, and Figs. 2 and 3 are the printed wiring board pattern width measuring device of the present invention. FIGS. 4 and 5 are explanatory diagrams showing the operation of a conventional printed wiring board pattern width measuring device. 4...Minimum pattern width 13...Printed wiring board 1
4...Image sensor 15...Image processing device 16...A/D converter 20...Pattern width measurement processing section (Fig.

Claims (1)

[Claims] In a pattern width measuring device for a printed wiring board, which processes an image signal of an imaged pattern of a printed wiring board with an image processing device to measure the width of the pattern, the image processing device is configured to measure the width of the pattern through the printed wiring board. A pattern width measuring device for a printed wiring board, characterized in that a pattern width measuring section is provided for determining the minimum radius between the outer image of the pattern from the center thereof and subtracting the radius of the through hole from this minimum radius.