JPH0626822A - Pattern inspection method - Google Patents

Abstract

PURPOSE:To measure the height of a land pattern by the shade inspection method. CONSTITUTION:The upper and lower widths of a land pattern 2 from the center of a land pattern 2 are detected and a land pattern side width from the center line in vertical direction of the 1 and pattern 2 to the edge of the land pattern 2 is measured. A shade length measurement value which can be obtained by measuring the length of a shade 3 by applying light to the land pattern 2 from the upper right or left par at a position corresponding to a land pattern side width is obtained. The ratio of the land pattern side width to the shape measurement length value is compared with the reference value, thus judging whether the height of the land pattern 2 is proper or not.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a height inspection of a wiring pattern on a printed board, especially a round pattern such as a land pattern.

In recent years, the density of printed boards has become higher and higher, and along with this, it is necessary to improve the inspection accuracy of wiring patterns.

[0003]

2. Description of the Related Art Conventionally, the height of a wiring pattern is inspected by irradiating the wiring pattern with light obliquely from above and measuring the length of the shadow to determine the quality.

FIG. 4 is a plan view for explaining the shadow length measurement of the conventional example. In the figure, the shadow 3 formed by irradiating the wiring pattern 1 with light obliquely from above is measured, for example, from the center line of the pattern to the end of the shadow in the shadow direction, and the measured value is compared with the reference value. The height of the wiring pattern 1 was inspected by making the above determination.

[0005]

However, the shadow inspection method is intended for the linear wiring pattern 1 of FIG. 5, and is suitable for the measurement of a pattern such as a land pattern 2 having a non-uniform line width such as a circular pattern. Absent.

An object of the present invention is to make it possible to measure the height of a land pattern by a shadow inspection method.

[0007]

To solve the above-mentioned problems, the upper and lower widths of the land pattern are detected from the center of the land pattern, and within the range of the upper and lower width, the land is measured from the vertical center line of the land pattern. The width of the land pattern up to the edge of the pattern is measured, and the length of the shadow formed by irradiating the land pattern in the lateral direction from diagonally above is measured at the position corresponding to the width of the land pattern. This is achieved by a pattern inspection method of determining the quality of the height of the land pattern by comparing the ratio of the lateral width of the land pattern and the shadow length measurement value with a reference value.

[0008]

In the present invention, in the height inspection of the wiring pattern by the shadow inspection method, the length from the center line of the land pattern to the land pattern edge (land pattern width) and the length of the shadow at the position corresponding to the length. The height of the land pattern is determined by comparing the ratio with the reference value.

The above ratio is obtained by normalizing with the land pattern width that the shadow becomes long at the center of the land pattern and becomes shorter toward the edge.
It can be said that the height of the entire land pattern is properly expressed.

[0010]

Embodiments FIGS. 1 (A) to 1 (C) are explanatory views of Embodiment 1 of the present invention. Fig. 1 (A): First, the vertical width of the land pattern (upper and lower boundary values) from the center position of the land pattern in the transmitted light image
Is detected.

FIG. 1 (B): The horizontal width of the land pattern (land pattern horizontal width) in the transmitted light image from the vertical center position obtained by detecting the vertical width of the land pattern.
Measure the length of.

FIG. 1C: In the shadow pattern image, the length of the shadow (shadow length measurement value) is measured. The length measurement range is within the vertical width of the land pattern, and the length measurement target is from the horizontal boundary value of the land pattern to the end of the shadow.

In determining whether the height of the land pattern is good or bad, the ratio between the width of the land pattern and the shadow measurement value is obtained, and when the ratio satisfies the reference value within the range of the vertical width of the land pattern, it is determined as a good product. To do.

FIGS. 2A to 2C are explanatory views of the second embodiment of the present invention. Fig. 2 (A): In the transmitted light image, the vertical width of the land pattern is detected from the center position of the land pattern.

FIG. 2 (B): In the transmitted light image, in the range of the vertical width of the land pattern from the vertical center position obtained by detecting the vertical width of the land pattern, and at both ends as shown in the drawing, The land pattern width is measured while leaving the long range.

FIG. 2C: In the shadow pattern image, the length of the shadow (shadow length measurement value) is measured. The length measurement range is within the vertical width of the land pattern, and the length measurement target is from the horizontal boundary value of the land pattern to the end of the shadow.

In determining whether the height of the land pattern is good or bad, the ratio between the width of the land pattern and the shadow measurement value is obtained, and when the ratio satisfies the reference value within the range of the vertical width of the land pattern, it is determined as a good product. To do.

In the first embodiment, it is assumed that the land pattern is close to a perfect circle. However, in many cases, this is not the case, and especially the measurement of the edge is unstable. Therefore, in the second embodiment, the inspection accuracy is improved by performing the measurement excluding the upper and lower ends.

FIGS. 3A and 3B are explanatory views of the third embodiment of the present invention. In Examples 1 and 2, the reference value of the quality judgment with respect to the ratio of the land pattern width and the shadow length measurement value was fixed, but
It is also possible to change this reference value by the distance in the vertical direction from the center of the land pattern.

Normally, the shadow of the land pattern swells as it approaches the center in the vertical direction, as shown in FIG. 3 (B). According to the present invention, whether the height of the pattern is good or bad is judged based on the ratio of the pattern and the shadow thereof. Therefore, the expansion ratio of the shadow can be dealt with by changing the judgment ratio depending on the vertical position as shown in FIG. You can

FIG. 3 (A) shows the relationship between the land pattern width and the pass / fail judgment ratio of the shadow measurement value. As described above, since the shadow increases in bulge as it approaches the center, the length measurement value of the shadow is very small at the upper and lower ends of the land pattern and large at the center.

Therefore, the reference ratio (judgment ratio) of the land pattern width / shadow length measurement value with respect to the vertical positions A, B, C of the land pattern becomes larger toward the center.

In the embodiment, the round pattern has been described as the land pattern, but the present invention can be applied not only to the round pattern but also to a pattern having a non-uniform line width.

[0024]

INDUSTRIAL APPLICABILITY The present invention can cope with the measurement of the height of a round pattern such as a land pattern by the shadow inspection method. This has contributed to the expansion of the range of application of pattern inspection and the improvement of accuracy.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of Embodiment 3 of the present invention.

FIG. 4 is a plan view illustrating shadow measurement of a conventional example.

FIG. 5 is a plan view of a wiring pattern

[Explanation of symbols]

 1 Linear wiring pattern 2 Land pattern 3 Shadow

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Gotoshi Ando 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Limited

Claims (1)

[Claims] 1. The vertical width of the land pattern is detected from the center of the land pattern, and the horizontal width of the land pattern from the vertical centerline of the land pattern to the edge of the land pattern is measured within the range of the vertical width. The length of the shadow formed by irradiating the land pattern in the lateral direction from diagonally above is measured at a position corresponding to the lateral width of the land pattern to obtain a shadow measurement value, and the shadow measurement value and the land are measured. A pattern inspection method comprising: comparing a ratio with a pattern width with a reference value to determine whether the height of the land pattern is good or bad.