JP2825281B2 - Inspection equipment for printed wiring boards - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board inspection apparatus capable of detecting, with high accuracy, an unetched portion or a missing portion in a wiring pattern.

(Prior art)

As shown in FIG. 9, the wiring pattern provided on the printed wiring board may be insufficiently etched for some reason, resulting in an unetched portion 91 between the wiring patterns 9, 9. The remaining etching portion 91 electrically shorts the wiring patterns 9 and 9.

On the other hand, as shown in FIG. 10, a missing portion 95 may be formed in the wiring pattern 9 in the wiring pattern 9 when the etching is partially excessive. The missing portion 95 cuts off the electrical connection in the wiring pattern 9.

For this reason, in the printed wiring board, an inspection is performed to determine whether or not the above-mentioned etched remaining portion 91 and the missing portion 95 are present, and the printed wiring board is discriminated as pass or reject.

Conventionally, as an inspection apparatus used for such an inspection, there is an apparatus using a comparison method. The inspection apparatus is a method of directly comparing master data with work data obtained from a wiring pattern on a printed wiring board to be inspected to determine the presence or absence of a defect. In the comparison method, the master data and the work data are aligned (shift amount correction), a mismatch portion between the two is checked, and a mismatch portion having a certain size or more is output as a defect.

As the master data, there is a case where CAD data at the time of design is used, or a case where a printed circuit board that has actually passed inspection is read by a CCD camera or the like.

[Problem to be solved]

However, in the above-mentioned conventional method, when the master data is CAD data, the master data does not coincide with the pattern width of the work data, so that positioning may not be performed.

Even when the master data is based on a printed wiring board that has passed the inspection, perfect alignment with the work data may not be possible due to uneven etching or expansion and contraction of the product.

As described above, since the master data and the work data have an inevitable slight displacement at the time of alignment, a defect having a size smaller than the displacement cannot be detected even if it is a serious defect.

Further, in the above-mentioned conventional method, since the defect is determined only by the size of the mismatched portion, the unevenness of etching that does not deserve a serious defect is excessively detected. Therefore, the false alarm rate is high.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a printed wiring board inspection apparatus capable of detecting an etching remaining portion and a missing portion with high accuracy.

[Solutions to solve the problem]

The present invention relates to an inspection apparatus for inspecting a wiring pattern for defects on a printed wiring board, the inspection apparatus comprising: an imaging device for reading the wiring pattern; work data obtained by the imaging device; Means for positioning the workpiece, and comparing the workpiece data and the master data positioned by the positioning means with each other to detect a non-coincidence portion. A first filter unit for selecting an unmatched shape that allows a mismatch of a predetermined size or more to pass through among the mismatch data of the remaining portion of the etching obtained by the comparing unit, and the alignment unit. Based on the amount of deviation that always occurs between the position-corrected master data and work data A first filter unit for master check for checking the presence / absence of a pattern of position-corrected master data in an area of a size and outputting output data if there is no pattern; and a certain size or more which is an output of both first filter units. A first AND gate unit which takes a logical product of data indicating the presence / absence of the unmatched shape of the remaining etching and data indicating the presence / absence of the master pattern in the area by negative logic; The unmatched portion having a certain size or more is determined based on the amount of misalignment constantly generated between the position-corrected master data and the work data obtained by the positioning means and the second filter for mismatched shape selection to be passed. Check the presence / absence of a pattern of position-corrected master data in an area of A second filter unit for the master check issues a data, said two second
A second AND which is a logical product of data indicating presence / absence of a missing / mismatched shape having a size equal to or larger than a predetermined size, which is an output of the filter unit, and data indicating the presence / absence of the master pattern in the area by positive logic
A printed wiring, comprising: a gate unit; and a defect counting unit that counts the defect data of the unetched part obtained by the first AND gate unit and the defect data of the missing part obtained by the second AND gate unit. In the board inspection device.

The most remarkable point in the present invention is that the comparing means separates the mismatched data of the etched remaining portion and the mismatched data of the missing portion, and then the mismatched data of the etched remaining portion is removed by the first and second filter sections. Is to be inspected by the second filter unit.

In the present invention, as described above, the master data
Uses AD data, data read from an actual board that has passed inspection, and the like.

Further, the positioning means is a device for performing positioning between the work data read from the printed wiring board as the object to be inspected and the standard master data. As a result, the wiring pattern on the printed wiring board is aligned with the wiring pattern of the master data, and the comparison means prepares for comparison.

The comparing means compares the two data positioned by the positioning means, and detects a mismatched portion. If the mismatched portion is a surplus portion that does not exist in the master pattern, the mismatched portion is determined as mismatched data of the “remaining portion to be etched”. On the other hand, if the mismatched portion is a missing portion that exists in the master pattern but does not exist in the work data, the mismatched portion is determined to be “missing portion” mismatched data. Then, the mismatch data of the remaining portion of the etching is transmitted to the first filter for mismatching shape selection, and the mismatch data of the missing portion is transmitted to the second filter for mismatching shape selection.

The first and second filter units for discriminating mismatched shapes are devices for limiting notable points in the mismatched data. The first and second filter units are filters that take into account inspection shapes such as disconnection and short-circuit, inspection product information, and the like. Adopt shape. However, unlike a general comparison method, the filter section does not need to cut off a mismatched portion having a size equal to or less than the positional deviation amount (see the embodiment).

The first and second filter units for master check are:
This device checks the master data using a certain rule and outputs it only when the rule is met. The position-corrected master data obtained by the positioning means is used as the master data.

In this master check filter section, the direction of the check area of the master data to be checked,
The distance is determined in advance. These are set based on the position correction capability of the inspection device, the detected defect item, and the like (embodiment).

What is necessary here is that the location of the image being processed by the mismatch shape selection filter matches the location of the image being processed by the master check filter. This substantially means that the master data near the point where the mismatch has occurred is simultaneously checked.

The first and second AND gate units are devices that take the logical product of the outputs of the mismatch shape selection filter and the master check filter. When the unmatched shape has a certain shape and size, the output of the AND gate is enabled when the condition of the master data near the point matches a certain rule. That is, true defect data is output.

The defect counting means is a device for counting the defect data output from the first and second AND gates, and the terminal is a device for outputting the counting data.

(Operation)

In the inspection apparatus of the present invention, the master data and the work data read from the object to be inspected are aligned by the alignment means, and the position-corrected work data and master data are sent to the comparison means. The comparing means compares the two data and detects a mismatched portion between the two data. The surplus portion among the non-coincidence portions is determined as non-coincidence data of the remaining etching portion, and is transmitted to the non-coincidence shape selection first filter portion.

On the other hand, the above-mentioned insufficiency portion among the inconsistency portions is determined as the inconsistency data of the missing portion, and is transmitted to the inconsistency shape selection second filter unit.

Therefore, in the former first filter for mismatched shape selection, the mismatched portion having a certain size or less is cut,
Any further mismatch is allowed to pass. At the same time, the position correction stack master data sent from the positioning means is transmitted to the first master check filter.

The first filter for master check is a spatial filter of a rule that outputs if a certain finite area of the master is the entire base material.

By taking the logical product of the outputs of the two first filters in the first AND gate, true data of the remaining etching can be obtained. In this comparison inspection, it can be seen that a pattern in which the pattern portion of the master data does not exist in the vicinity of the mismatched portion as the etching remaining portion is determined as the etching remaining portion. The data of the remaining portion of the etching is sent to the defect counting section.

In the same manner, the comparative inspection is performed in the second filter unit for mismatched shape selection, the second filter unit for master check, and the second AND gate unit. The rule is selected so that a part having no is determined as a true defective part. The data of the true missing part is sent to the defect counting part.

(Effect)

According to the present invention, the output of the comparison inspection is distinguished from the mismatch data of the remaining portion of etching and the mismatch data of the missing portion,
Moreover, since the shape of the master data in the vicinity of the mismatched portion is used for defect determination, a true etching remaining portion and a true missing portion can be detected with a high degree of accuracy equal to or higher than the “position correction function capability”. Can be provided.

〔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 device of this example is a printed circuit board.
A CCD camera 11 as an image pickup device for reading a wiring pattern 101 on 10, an A / D converter 12 for converting an analog signal of the CCD camera 11 into a digital signal, a positioning unit 13,
A comparing unit 14, a first filter unit 15 for discriminating shape discrimination for inspecting discrepancy data of the remaining portion of the etching, a first filter unit 151 for master check, a first AND gate unit 16,
The second for mismatched shape selection to check the mismatched data of the missing part
Filter unit 17, 2nd filter unit 1 for master check
71, a second AND gate unit 18, a defect counting unit 31 for inputting defect data signals from the first and second AND gate units, and a terminal 3.
Consists of two. Further, a master memory 21 having a master storage means 210 is connected to the positioning means 13.

The master adopting means 210 is a device for storing master data, which is standard image information. As the means, for example, when designing the wiring pattern,
There is a means for converting CAD data (vector data) so as to match work data (raster data) from an image pickup apparatus and keeping the converted data as master data. There is also a means for storing data read from a pass wiring pattern (master substrate) by an imaging device in advance.

1, master data is taken into the master memory 21 from the master substrate via the CCD camera 11, the A / D converter 12, and the path 210 without using the master adopting means 201. Route data 212
Means for transmitting to the positioning means via the.

Therefore, when inspecting with the above inspection apparatus, first, the wiring pattern 101 on the printed wiring board 10 is
Work data is read by the camera 11 and input to the positioning means 13 via the A / D converter 12. On the other hand, master data is input to the positioning means 13 from the master memory 21 through a path 212.

Then, in the positioning means 13, the work data and the master data are positioned. However, here, as described above, complete position correction is impossible, and there is always a part that cannot be completely corrected. In practice, there is a slight shape mismatch between the standard master data and the printed circuit board to be inspected. For this reason, a tentative comparison is performed by the comparing means 14 as described below, and the data is separated into non-coincidence data of the etching remaining portion and the missing portion. Inspection is carried out.

As the positioning means, for example, Japanese Patent Application Laid-Open No. 62-1400
There is a device disclosed in Japanese Patent Publication No. 09-2009.

Next, the work data subjected to the position correction in the positioning means 13 and the master data are input to the comparing means 14, and the two are compared to detect information on a mismatched portion. As the information of the non-coincidence part, a pattern portion in which the work data is redundant with respect to the master data (reference numeral in FIG.
Some parts have a pattern part 91 (the part indicated by reference numeral 95 in FIG. 4 described later). Here, the former surplus pattern portion indicates an unetched portion, and this information is used as mismatch data of the unetched portion. The latter indicates a missing part, and this information is regarded as mismatched data of the missing part.

The comparison means 14 includes, for example, a combination of logic elements as shown in FIG.

That is, the mismatch data of the remaining portion of the etching is the second data.
As shown in the figure, when the pattern 9 of the test object (within the solid line frame) and the master pattern 8 (within the dotted line frame) are compared, the pattern 9 is detected as a mismatched portion 91. However, here, as well as the mismatch data of the remaining portion of the etching, the mismatch data based on the positional shift 7 (hatched portion) in both the patterns 8 and 9 is also included. The position shift 7 has a shift amount Y.

Further, as shown in FIG. 4, the mismatch data of the missing part is detected as the mismatch part 95 when the pattern 9 of the test object and the master pattern 8 are compared.
However, here, in addition to the inconsistent data of the missing portion, inconsistent data based on the positional deviation 7 in the patterns 8 and 9 is also included. The position shift 7 has a shift amount Y.

Thus, the comparing means 14 discriminates the above two types of non-coincidence data, and outputs the non-coincidence data of the remaining portion of the etching to the first filter 15 for non-coincidence shape selection, and the non-coincidence data of the missing portion to the second filter for non-coincidence shape selection. Output to the filter unit 17.

In the first filter unit 15 for mismatched shape selection, a quantization error of ± 1 image at the time of conversion in the A / D conversion unit 12 is cut for mismatched data of the remaining portion of the etching, so that the mismatched data has a size of two pixels or more. Pass the part. The mismatched data that has passed is output to the first AND gate unit 16 (7th
Figure).

On the other hand, in the mismatching shape selection second filter unit 17, a mismatching portion having a length (the width is not required) of 80% or more of the width of the pattern to be inspected is determined for the mismatching data of the missing portion. Make a linear filter to pass. The passed mismatch data is output to the second AND gate unit 18 (FIG. 8). This filter unit is prepared for each direction.

The filter unit is a general spatial filter.

Next, the first or second filter unit for master check checks master data (master image). The master data used here is used by the positioning means 13.
This is tentative position-corrected data obtained in step (1).

Thus, in the first filter unit for the master check, as shown in FIG.
The state of the master pattern 8 is checked for a circular area having a diameter twice as large as the deviation amount Y. Circular areas A, B, C in the same figure
Indicates the check area. If there is a master pattern 8 (dotted frame) in the circular areas A and B, there is no output from the filter. On the other hand, when there is no master pattern 8 in the circular area C as in the case of the circular area C, there is an output from the filter (FIG. 7).

Next, in the second filter for master check, as shown in FIG. 5, the state of the master pattern 8 is checked up to a linear area having a length three times the displacement Y of the displacement 7. The linear areas J, K, and L in the figure indicate the check areas. Then, when the base material portion of the master is caught in a part of the area like the linear areas J and L, there is no output from the filter.

On the other hand, when the master pattern is caught in the whole area, as in the linear area K, there is an output from the filter (FIG. 8). However, the direction of the one-dimensional check area is a direction that crosses the filter direction in the second filter unit for mismatched shape selection by 90 degrees. For example, for unmatched data that has passed the horizontal filter, a master check is performed using a linear area in the vertical direction (FIG. 8).

The inspection results of the first and second filter units for master check are sent to the first and second AND gate units, respectively.

A spatial filter is used for the first and second filter units for master check, similarly to the filter unit for selecting mismatched shapes.

7 and 8 show a filter for discriminating a mismatched shape,
This figure shows the relationship between the master check filter and the AND gate. It is shown that true defect information is output from the AND gate output when the condition of the master image in the vicinity of the mismatch occurrence point passing the mismatch shape selection filter conforms to the check rule.

As described above, according to the inspection apparatus of the present embodiment, the discrepancy data of the remaining etching portion and the discrepancy data of the missing portion are distinguished and compared with the master data for inspection. Can be detected with high accuracy.

[Brief description of the drawings]

1 to 5 show an inspection apparatus according to an embodiment of the present invention. FIG. 1 is a block diagram of the inspection apparatus, and FIGS. 2 and 3 are explanatory diagrams of mismatch data of an etching remaining portion and a comparison inspection thereof.
4 and 5 are explanatory diagrams of the mismatched data of the missing portion and the comparison inspection thereof, FIG. 6 is a logic circuit diagram of the comparing means, FIG. 7 is a detection portion of the residual etching, and FIG. 8 is a detection of the missing portion. 9 and FIG. 10 are explanatory diagrams of a remaining portion and a missing portion in the wiring pattern. 7: misalignment, 8: master pattern, 9: pattern of inspected object, 91: etching remaining part, 95: missing part,

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01N 21/88 G01B 11/24 H05K 3/00

Claims (1)

(57) [Claims] 1. An inspection apparatus for inspecting a wiring pattern for defects on a printed wiring board, the inspection apparatus comprising: an imaging device for reading the wiring pattern; work data obtained by the imaging device; And comparing the work data and the master data that have been aligned by the alignment means with each other, and detecting a mismatched portion.
Comparing means for classifying non-coincidence data of the remaining part of the etching and non-coincidence data of the missing part; The presence / absence of a pattern of position-corrected master data in an area having a size based on the amount of deviation that always occurs between the first data filter unit and the position-corrected master data and work data obtained by the positioning means. And a first filter unit for master check, which outputs output data if there is no pattern, and the presence / absence data of a non-matching shape having an etching residue equal to or larger than a certain size, which is the output of both first filter units, and the above-mentioned master pattern. A first AND gate for performing a logical AND operation with data indicating the presence / absence of the area in negative logic; The mismatched data having a predetermined size or more among the mismatched data of the missing portion obtained by the means is passed through a second filter for mismatched shape selection, and the position-corrected master data and work data obtained by the positioning means. A master-check second filter unit for checking the presence / absence of a pattern of position-corrected master data in an area of a size based on the amount of displacement that is constantly generated between the two and outputting output data if there is a pattern; A second AND gate unit for performing an AND operation on data indicating presence / absence of a missing / mismatched shape having a size equal to or larger than a predetermined size, which is an output of both second filter units, and data indicating the presence / absence of the master pattern in the area by positive logic The missing data of the remaining part of the etching obtained by the first AND gate and the defect data of the missing part obtained by the second AND gate are tabulated. That the defect aggregate portion inspection apparatus of printed wiring board, wherein become more that.