JP2753732B2 - Inspection equipment for printed wiring boards - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an inspection device for detecting a defect shape of a wiring pattern on a printed wiring board.

(Prior art)

A wiring pattern on a printed wiring board may have a defect shape due to short-circuit of a wire, adhesion of dust or the like in a manufacturing process. Therefore, various inspection devices for detecting such a defect shape have been proposed.

Such an inspection device includes an imaging device such as a CCD camera that reads a wiring pattern on a printed wiring board, an A / D converter that converts an analog signal of the imaging device into a digital signal, and a defect shape from the digital image signal. There is an inspection apparatus having defect detection means for detecting.

However, as shown in FIG. 6 and FIG.
In the inspection of 90, the inspection device may determine that the fragment portion 91 and the short-circuit portion 92 have a defect shape. However, actually, the fragment portion 91 is an open end of a clean pattern even though it looks like a disconnection, and the short-circuit portion 92 is a normal connection portion.

Therefore, in such a case, a processing system for selecting whether or not the data is true defect data is required.

Conventionally, as an inspection device for that purpose, a device that inspects a normal wiring pattern, registers a portion determined to be a defect shape at that time, that is, pseudo defect data in a memory, and verifies this at the time of an actual inspection. is there. That is, when inspecting a wiring pattern at the time of actual inspection, pseudo defect data stored in the memory is read out and collated with defect candidate data detected from the wiring pattern. When the defect candidate data matches the pseudo defect data, the defect candidate data is determined not to be true defect data. When the defect candidate data does not match, it is determined to be true defect data.

In the comparison, a mask table in which a mask is applied to a portion of the pseudo defect data is used.

 The above-mentioned judgment method is shown in FIG.

That is, the pseudo defect data obtained from the normal wiring pattern is registered in the mask table 96 first. The cells 961 and 969 are masked as pseudo defect data in the mask table (this is referred to as mask data). Cells 962 to 967 that are not pseudo defect data are not masked. On the other hand, in the data table 95 obtained from the inspected wiring pattern, defect correction data detected as a defect shape is stored in cells 951, 953, and 959.

Therefore, when the mask table 96 is compared with the data table 95, the cells 951 and 9
Since 59 defect candidate data matches cells 961 and 969 of pseudo defect data, it is determined that these two data are not defect shapes. On the other hand, the cell 953 of the defect candidate data is determined to be true defect data 973 because there is no similar pseudo defect data.

Therefore, in the above inspection method, the position of the mask with respect to the data table is prevented in order to prevent the pseudo defect from being leaked in the collation process, that is, to prevent the defect from being judged as true defect data even though it is originally pseudo defect data. Candidates are needed.

Therefore, the following two means are generally used as the position correcting means.

One of them is an enlarged mask method in which a large mask is provided. The other is a peripheral mask collation method that also performs collation with peripheral masks.

In the enlarged mask method, as shown in FIG. 9, in the mask table 81, the range to be masked is set to the cell 815 of the pseudo defect data at the center and the cell 8 adjacent thereto.
It is 9 times larger than 11-814,816-819. Then, as shown in FIG. 10, in the data table 82,
The defect candidate data cell 828 obtained from the inspection object is compared with the enlarged mask cells 811 to 819 in the mask table 81. As a result of the comparison, it is determined that the defect candidate data cell 828 is not true defect data.

The latter peripheral mask matching method uses a defect candidate data cell 828 in the data table 82 as shown in FIG.
Is compared with the mask table 81, the cell 811 in the portion matched with the defect candidate data cell 828 is not pseudo defect data, so that the defect candidate data cell 828 is determined to be true defect data. However, the above cell 811 of the mask table 81
The collation with the cells (8) in the vicinity of is also performed. As a result, since there is a cell 815 of pseudo defect data, it is determined that the defect candidate data cell 828 is not true defect data.

[Problem to be solved]

However, in the former enlarged mask method, when the printed wiring board has a fine (precision) pattern, the defect candidate data close to the position corresponding to the mask cell is determined to be not true defect data due to the enlarged mask. Is not an appropriate method.

In the latter peripheral mask matching method, the size of the mask is determined based on the position correction amount. For example,
As shown in FIG. 12, in the case of position correction of ± 150 μm, the mask size is set to 100 μm, and the periphery of the mask is compared.

Therefore, if the position correction is reduced for fine patterns, it is necessary to increase the total memory capacity of mask data for developing a mask. For example, when the size of the mask cell is reduced to 100 × 100 μm, the capacity of the mask memory is required to be four times as large as that when the size of the mask cell is 200 × 200 μm. Therefore, the cost of the inspection apparatus is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and aims to provide an inexpensive printed circuit board inspection apparatus capable of reducing position correction while maintaining a small mask memory capacity.

[Solutions to solve the problem]

The present invention relates to an imaging device that reads a wiring pattern on a printed wiring board, a defect detection unit that detects defect candidate data from an image signal of the imaging device, and a defect detection unit that detects a defect candidate data detected by the defect detection unit. Defect selection means for selecting whether the data is data, data collection means for totalizing true defect data selected by the defect selection means, and display means for displaying data of the data collection means; and The defect selection means includes a mask memory for registering and reading the pseudo defect data, and a defect candidate data for dividing the defect candidate data into a mask cell size or less.
An inspection apparatus for a printed wiring board, comprising: a time division unit; and a mask collation unit for collating the defect defect candidate data with the mask of the pseudo defect data.

In the present invention, the most remarkable point is that a defect selection unit including the mask memory, the defect candidate data / time division unit, and the mask comparison unit is provided.

The pseudo defect data is pseudo data that is inspected using a normal wiring pattern in advance and is detected as if it were a defect shape, despite the fact that it is originally a normal shape. The pseudo defect data is registered in the mask memory and read at the time of collation.

The defect candidate data is data that is detected as having a defect shape when a wiring pattern of a printed wiring board to be inspected is inspected, and is data that is collated with the mask of the pseudo defect data. is there.

Further, the defect candidate data / time division unit is means for dividing the defect candidate data into a cell size smaller than the cell size (cell size) of the mask of the pseudo defect data. For example, the defect candidate data is calculated as 1/9 of the mask size.
Divide into 1 / 16th size.

The matching in the mask matching section is performed between the divided cells and the mask cells from the mask memory. At this time, each of the divided cells is compared with a portion where the divided cell itself is located and a mask cell in a portion adjacent thereto.

The data tabulation means is a means for counting and recording data determined by the defect selection means, and the display means is a means for reading and displaying necessary data from the data counting means.

Further, since an image signal output from an imaging device is generally an analog signal, it is converted into a digital signal by an A / D converter.

(Operation)

In the inspection device of the present invention, the image signal read by the imaging device enters the defect detection means, and the presence or absence of a signal corresponding to the defect shape is determined. If the defect detection means determines that there is a defect shape, the signal is sent to the defect candidate data / time division unit of the defect selection means as defect candidate data, and is divided into smaller pieces than the cell size of the mask.

On the other hand, in the mask collation unit, pseudo defect data is read from the mask memory, and the pseudo defect data and the divided defect candidate data sent from the defect candidate data / time division unit are collated as described above. That is, for the portion where the divided defect candidate data itself is located and the adjacent portion,
Match with the mask cell. Then, the true defect data obtained as a result of the collation is sent to the data totaling means and further to the display unit.

In the mask collation unit, each of the defect candidate data divided into small pieces is collated with the mask of the pseudo defect data as described above.

(Effect)

As described above, according to the inspection apparatus of the present invention, the defect candidate data is divided and used for collation, and the mask size of the pseudo defect data is not reduced, so that it is not necessary to increase the mask memory capacity. Further, since the defect candidate data is divided and collated, the position correction can be reduced.

Therefore, it is possible to provide an inexpensive printed wiring board inspection apparatus which is particularly effective for inspection of fine wiring patterns.

〔Example〕

An inspection apparatus for a printed wiring board according to an embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 1, the inspection apparatus of this embodiment includes an imaging device 21 that reads a wiring pattern 11 on a printed wiring board 10 and an A / D converter that converts an analog signal of the imaging device into a digital signal.
It comprises a D converter 22, a defect detecting means 23, a defect selecting means 3, a data totaling means 41, and a terminal 42 as a display means. In addition, the defect selection means includes a defect candidate data / time division unit.
It has a mask comparing unit 32 for comparing the signals sent from both, 31 and a mask memory 33.

The defect detecting means detects whether or not there is any data (defect candidate data) that is temporarily determined to have a defect shape in the image signal sent from the A / D converter 22. If there is defect candidate data, the signal is sent to the defect candidate data / time division unit 31 of the defect selection means 3 and is divided into a smaller size than a mask cell size described later.

On the other hand, pseudo defect data is registered in the mask memory 33 of the defect selection means 3. The pseudo defect data is temporary defect data that is inspected in advance using a normal wiring pattern and is normally normal, but is determined to have a defect shape by the defect detection unit 23.

Thus, the individual data of the divided defect candidate data is compared with the mask data of the pseudo defect data in the mask memory 33. This will be described with reference to FIGS.

First, as shown in FIG. 2, it is assumed that the data table 51 obtained by the defect detecting means 23 has nine cells A to I. Each size of the cells A to I is stored in a mask memory.
The size is the same as the size of each of the cells A to I of the mask table 52 (FIG. 3) in 33. For example, both have a size of 200 × 200 μm.

Therefore, in the defect candidate data / time division unit 31, the E that exists as the defect candidate data in the data table 51 is stored.
Divide the part into 1/3 length and 1/3 horizontal. That is, E
Is divided into nine cells e1 to e9. The cell size of the divided cells e1 to e9 is 1/9 of the cell size of the mask table.

Next, as shown in FIG. 4, of the defect candidate data (cell E) of the data table 51, the data of e5 is collated with the pseudo defect data (cell E) of the mask table 52. This collation is performed for the mask cell of the portion where e5 itself is located (the center portion of E of the mask table 52) and the portion where e5 is adjacent (around the center portion of E of the mask table 52). In other words, the cell e of the mask table 52 is collated for e5.

The cells e1 to e4 and e6 to e9 are collated as shown in FIGS. 4 and 5, respectively. That is,
For example, regarding the cell e7, the mask cell portion (cell E of the mask table 52) of the portion where the cell e7 itself is located and the portion adjacent thereto (the cell E of the mask table 52)
D, G, H).

As a result of collation as described above, when it is determined that the data is true defect data, the data is transmitted to the data totaling means 41.

As described above, in the inspection apparatus of the present embodiment, the defect candidate data is subdivided into cells smaller than the cell size of the mask, and each subdivided cell is compared with the mask of the mask table as described above. The size as it is is fine. Therefore, it is not necessary to increase the capacity of the mask memory as in the prior art, and the cost does not increase.

In addition, since the collation is performed in the segmented state as described above, the position correction can be reduced. Therefore, excellent performance can be exhibited in the inspection of fine patterns.

[Brief description of the drawings]

1 to 5 show a printed wiring board inspection apparatus according to an embodiment, FIG. 1 is a block diagram thereof, FIG. 2 is an explanatory view of a data table, FIG. 3 is an explanatory view of a mask table, FIG. 4 and 5 are explanatory diagrams showing the comparison between the divided cell and the mask cell, FIGS. 6 and 7 are explanatory diagrams of the pseudo defect shape, and FIG. 8 is a diagram showing defect candidate data, pseudo defect data and true defect data. FIGS. 9 and 10 are explanatory diagrams showing the relationship between defects, FIGS. 9 and 10 are explanatory diagrams of a conventional enlarged mask method, FIG. 11 is an explanatory diagram of a conventional peripheral matching method, and FIGS.
FIG. 1 is an explanatory diagram of a conventional position correction. 51, 82, 95 ... Data table, 52, 81, 96 ... Mask table, 91 ... Fragment as pseudo-defect, 92 ... Short-circuit part as pseudo-defect, A ~ I ... cell, e1 ~ E9 …… Split cell,

Claims (1)

(57) [Claims] An image pickup apparatus for reading a wiring pattern on a printed wiring board, defect detection means for detecting defect candidate data from an image signal of the image pickup apparatus, and a defect candidate data detected by the defect detection means are set to true. Defect selection means for selecting whether or not the data is defect data; data collection means for totalizing true defect data selected by the defect selection means; and display means for displaying data of the data collection means. The defect selection means includes a mask memory for registering and reading pseudo defect data, a defect candidate data / time division unit for dividing the defect candidate data into a cell size equal to or smaller than a mask cell size, a divided defect candidate data and a pseudo defect. An inspection apparatus for a printed wiring board, comprising: a mask collation unit for collating a data with a mask.