JPH05240627A - Pattern inspecting device - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a pattern inspection apparatus, and an object thereof is to provide a pattern inspection apparatus which sets a defect level of a defect pattern in a plurality of stages and detects the defect level. A pattern shape reading means for reading a pattern shape of a wiring pattern formed on an object to be measured, a defect level of the wiring pattern is set in a plurality of stages, and a plurality of pattern shapes serving as threshold values of the defect level are stored. And a pattern shape comparison means for comparing the pattern shape stored in the pattern shape storage means with the pattern shape read by the pattern shape reading means, and the comparison result by the pattern shape comparison means. , The presence or absence of a defect in the wiring pattern, and the defect level are inspected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern inspection device, and more particularly, to a metal wiring made of, for example, a copper foil on a printed wiring board, which is suitable for use in the field of printed wiring board inspection. The present invention relates to a pattern inspection device for inspecting a defect of a wiring pattern and a defect level.

In recent years, electronic circuits are generally constructed by electrically connecting electronic components arranged at predetermined positions on a printed wiring board by metal wiring formed on the printed wiring board. is there. However, when electricity is applied in a state where the wiring pattern formed on the printed wiring board is defective, there is a risk that the wiring pattern will be broken, and the mounted electronic components and power supply will be damaged.

Therefore, it is necessary to inspect the wiring pattern of the electronic circuit for defects before energization.

[0004]

2. Description of the Related Art A conventional pattern inspection apparatus of this type is shown in FIG. This pattern inspection apparatus is roughly composed of a pattern shape reading means 1, a pattern shape storing means 2, and a pattern shape comparing means 3. The pattern shape reading means 1 reads the pattern shape of a wiring pattern such as a copper foil wiring which is a metal wiring formed on a printed wiring board which is an object to be measured.

The pattern shape storage means 2 stores a wiring pattern serving as a reference threshold value for determining whether the wiring pattern is normal or defective. Pattern shape comparison means 3
Is for determining whether the read wiring pattern is normal or defective by comparing the pattern shape read by the pattern shape reading unit 1 with the pattern shape stored in the pattern shape storing unit 2. Is.

In the above structure, by comparing the wiring pattern of the metal wiring on the printed wiring board read by the pattern shape reading means 1 with the wiring pattern serving as the reference threshold, it is determined whether or not there is a defect in the wiring pattern. To be inspected.

[0007]

However, in such a conventional pattern inspecting apparatus, the read wiring pattern on the printed wiring board is compared with a wiring pattern serving as a reference threshold to obtain a wiring pattern. Since only the presence or absence of defects is inspected, when the pattern shape is coded by the method shown in FIGS. 2, 4 and 5 described later, as shown in FIGS. , The metal wiring pattern is classified as either normal or defective, and it is impossible to inspect a wiring pattern such as a defect having a defect level that can be judged to be normal depending on use conditions. There was a point.

Incidentally, FIG. 9A shows that the degree of defect is classified into either 0 (normal) or 1 (defect), and that it does not take an intermediate value. 9
FIG. 9B shows a structure of a corresponding conventional reference dictionary, showing a state in which a defective code area and a normal code are divided into areas and shape codes are stored in each area, and FIG. Is an example of the conventional defect display, and the position of the defect is displayed as a dot on the CRT or plotter, but any defect is also displayed as a black dot, for example.

That is, in general, there is a kind of ambiguity in distinguishing whether a wiring pattern is normal or defective. Usually, a wiring pattern of a printed wiring board is a pattern that causes electrical failure such as conduction failure or insulation failure. Since the shape is regarded as a defect, for example, a diagram for explaining a disconnection defect as shown in FIGS. 10A to 10C will be described as an example.
As shown in FIG. 10 (a), a complete disconnection pattern should obviously be a defect, but as shown in FIG. 10 (b), a slightly thin wiring pattern is shown in FIG. 10 (a). This is an intermediate state between the defect pattern and the normal pattern shown in FIG. 10C, and whether or not this should be a defect depends on the use conditions and the like, and is finally determined by the operator.

Therefore, by merely inspecting for normality / defects, a wiring pattern which should be judged to be normal is erroneously judged to be defective, and so-called over-detection increases the number of defective portions, resulting in extra time required for correction work. There is a problem that the number of defects increases and that defects are overlooked due to the judgment that the wiring pattern that should be judged as a defect is a normal pattern.

[Purpose] Therefore, an object of the present invention is to provide a pattern inspection apparatus which sets a defect level of a defect pattern in a plurality of stages and detects the defect level.

[0012]

In order to achieve the above object, a pattern inspection apparatus according to the present invention has a plurality of pattern shape reading means for reading a pattern shape of a wiring pattern formed on an object to be measured and a plurality of defect levels of the wiring pattern. A pattern shape storage unit that stores a plurality of pattern shapes that are set in stages and serve as a threshold of the defect level, a pattern shape stored in the pattern shape storage unit, and a pattern shape read by the pattern shape reading unit. And a pattern shape comparison means for comparing the above-mentioned pattern shape comparison means, and is configured to inspect the comparison result by the pattern shape comparison means, the presence or absence of a defect in the wiring pattern, and the defect level.

In this case, when the pattern shape of the wiring pattern is coded and stored in the pattern shape storage means and the defect level is detected based on the pattern shape, the defect level is output and displayed to the outside. It is effective to do.

[0014]

According to the present invention, the defect level of the wiring pattern is set to a plurality of levels by the pattern shape storing means, and a plurality of pattern shapes serving as the threshold of the defect level are stored and read by the pattern shape comparing means. The defect level of the pattern shape is inspected.

That is, the defect level is detected by setting the defect levels of the defect pattern in a plurality of stages.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a pattern inspection apparatus according to the present invention, and is a block diagram showing the overall configuration of this embodiment.
First, the configuration will be described.

In FIG. 1, the same numbers as the numbers given to the conventional example shown in FIG. 8 indicate the same parts. The pattern inspection apparatus of this embodiment is roughly divided into a pattern shape reading means 1, a pattern shape storing means 2, and a pattern shape comparing means 3. The pattern shape reading means 1 includes a lens 4, a CCD 5, and a binarization circuit 6. , Memory circuit 7, length measuring circuit 8
The pattern shape storage means 2 is from the reference dictionary storage circuit 9, and the pattern shape comparison means 3 is from the comparison / determination circuit 1.
0, an output display device 11.

Reference numeral 12 denotes a printed wiring board which is an object to be measured, and 13 denotes metal wiring (in this case, copper foil wiring).
The pattern shape reading unit 1 reads the pattern shape while detecting the center position of the wiring pattern of the metal wiring 13 formed on the printed wiring board 12, and more specifically, the pattern data read by the lens 4 and the CCD 5. Is binarized by the binarization circuit 6, and then the storage circuit 7
In addition to storing and holding as image information, the length measuring circuit 8 measures the length of the pattern data in each direction and converts it into a shape code.

The conversion of the pattern data into the shape code is
As shown in FIG. 2, 0 °, 45 ° from a predetermined reference direction
°, 90 °, 135 °, 180 °, 225 °, 270
S (Short), C (Correc
t), L (Long), and OV (OVer) are longer than any of the lengths, codes shown in Table 1 (specifically, 2 bits × 8 directions' worth of codes) are assigned.

[0020]

[Table 1]

The reference dictionary storage circuit 9 which is the pattern shape storage means 2 stores a wiring pattern serving as a reference threshold for determining whether the wiring pattern is normal or defective, as a reference dictionary. As shown in the example of the degree of defect, the degree of defect is divided into several levels by the shape code (in this case,
The defect level is defined by being divided into 10 levels. In FIG. 3, the left side is an example of division of the metal wiring 13 for a disconnection defect and the right side is an example of division for a short circuit defect, and a, b, c, d, etc. are 0.
It is the code of Table 1 showing the length in each direction of °, 45 °, 90 ° and 135 °.

The pattern shape comparing means 3 compares the pattern shape read by the pattern shape reading means 1 with the pattern shape stored in the pattern shape storing means 2 by the comparison / determination circuit 10 to read the wiring. It is to determine whether the pattern is normal or defective, and the result is displayed by the output display device 11.

Next, the operation will be described. In the above configuration, the pattern shape reading means 1 is used to print the printed wiring board 1
When the pattern shape of the wiring pattern of the metal wiring 13 formed on the wiring 2 is read, the binarization circuit 6, the storage circuit 7,
The length measuring circuit 8 gives a shape code corresponding to the read wiring pattern.

Here, a method of giving a shape code to this wiring pattern will be described in detail. It should be noted that although there are several thousands of wiring patterns, the wiring patterns shown in FIG. 4 will be described as an example.
First, in the wiring pattern shown in FIG. 4A, the code “0110111” is set based on the code table shown in Table 1 with the longitudinal direction of the pattern shape being 90 ° (or 180 °).
001101110 "is added, and similarly, FIG.
In the wiring pattern shown in (b), the code "011
1101101101110 ″ is added.

However, in the case of a wiring pattern having a defect as shown in FIGS. 5A and 5B, as described above,
Since the pattern shape reading means 1 reads the pattern shape by detecting the center, the reading position is as shown by the alternate long and short dash line in the figure. That is, in the defective wiring pattern shown in FIG. 5A, the code "00001110000001" is used.
Similarly, in the defective wiring pattern shown in FIG. 5B, the code "11111101" is added.
11011111 ″ is added.

Therefore, since the code in FIGS. 5A and 5B is different from the code that should be obtained originally (the code in FIG. 4A), a defect in the wiring pattern is detected.
In the method of creating a reference dictionary by the reference dictionary storage circuit 9, as shown in the flowchart of FIG. 6, first, pattern information is read (step 1) and a shape code is generated (step 2).

Then, the occurrence frequency of the shape code is compared with a predetermined occurrence frequency number M (step 3), and if it is smaller than the occurrence frequency number M, the result is output to the output display device 11 (step 4). The degree of defect is determined (step 5), and the obtained shape code is registered in the defect dictionary as shown in FIG. 3 (step 6). On the other hand, if the shape code is generated more frequently than the number M of occurrences in the process of step 3 described above, this shape code is registered in the normal dictionary (step 7). This is because, in general, the frequency of occurrence of defective patterns is low, and therefore the one with a high frequency of occurrence can be regarded as a normal pattern.

As described above, in this embodiment, the reference dictionary storage circuit 9 sets the defect levels of the wiring patterns in a plurality of levels, and the reference dictionary storage circuit 9 stores a plurality of pattern shapes serving as thresholds for the defect levels. Therefore, the defect level of the defect pattern can be set in a plurality of stages, and the defect level of the pattern shape of the read wiring pattern can be detected.

Therefore, it is possible to strictly detect the defect level of the wiring pattern. Further, in this embodiment, as shown in FIGS. 7A and 7B, by setting the degree of defect in a plurality of stages, a color output display according to the defect level as shown in FIG. The resulting pattern defects are detected, including the degree of defects. As a result, a defect pattern intermediate between the normal pattern and the apparent defect pattern is also presented to the operator, and the defect is prevented from being overlooked or excessively detected.

Further, in this embodiment, since the variation in the degree of defects is statistically captured, the process control can be effectively performed, and the productivity can be improved.

[0031]

According to the present invention, the defect level of the wiring pattern is set to a plurality of levels by the pattern shape storage means, and a plurality of pattern shapes serving as the defect level threshold values are stored and read by the pattern shape comparison means. The defect level of the pattern shape of the wiring pattern is inspected.

That is, the defect level is detected by setting the defect levels of the defect pattern in a plurality of stages.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of this embodiment.

FIG. 2 is a diagram for explaining a coding example of a pattern shape.

FIG. 3 is a diagram showing an example of creating a reference dictionary in this embodiment.

FIG. 4 is a diagram for explaining a coding example of a shape code in a normal pattern.

FIG. 5 is a diagram for explaining a coding example of a shape code in a defect pattern.

FIG. 6 is a flowchart illustrating a method of creating a reference dictionary.

FIG. 7 is a diagram for explaining a process of an output result according to the present embodiment.

FIG. 8 is a block diagram showing an overall configuration of a conventional example.

FIG. 9 is a diagram for explaining a process of an output result according to a conventional example.

FIG. 10 is a diagram for explaining a disconnection defect.

[Explanation of symbols]

 1 pattern shape reading means 2 pattern shape storing means 3 pattern shape comparing means 4 lens 5 CCD 6 binarization circuit 7 storage circuit 8 length measuring circuit 9 reference dictionary storage circuit 10 comparison judgment circuit 10 11 output display device 12 printed wiring board ( Measurement target) 13 Metal wiring

Claims (2)

[Claims] 1. A pattern shape reading means for reading a pattern shape of a wiring pattern formed on an object to be measured, and a plurality of pattern shapes for setting a defect level of the wiring pattern in a plurality of steps and for providing a threshold for the defect level. Pattern shape storage means for storing the pattern shape storage means, and pattern shape comparison means for comparing the pattern shape stored in the pattern shape storage means with the pattern shape read by the pattern shape reading means. 2. The pattern inspection apparatus for inspecting the result of the comparison, presence / absence of defects of the wiring pattern, and defect level. 2. The pattern shape storage means stores the pattern shape of the wiring pattern in a coded form, and when a defect level is detected based on the pattern shape, the defect level is output and displayed to the outside. Claim 1 characterized by
The described pattern inspection device.