JP3291176B2 - Circuit pattern inspection method and inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit pattern inspection method and an inspection apparatus for inspecting a positional deviation of a circuit pattern formed on the front and back surfaces of an object to be inspected and inspecting a distance between a plurality of points of the circuit pattern. .

[0002]

2. Description of the Related Art In recent years, in the printed wiring board manufacturing industry,
Multilayer, high-density, fine pattern, and high precision printed wiring boards are rapidly advancing, and high reliability is required. In particular, in the case of a multilayer circuit board using a fine pattern, the inspection of the positional deviation of the circuit pattern between the layers has become a very important issue. That is, the circuit pattern is
Exposure mask film by exposure method, substrate after exposure,
It is formed on a substrate after printing by a printing method, a circuit board after etching, and the like, and it is necessary to perform a positional displacement inspection on these circuit patterns.

Generally, in a multilayer circuit board, in order to make electrical connection between layers, through holes or via holes are formed at positions corresponding to lands in each layer, and electrical connection portions such as plating are formed in these hole portions. Has formed. Here, when the optimum position of the through hole or the via hole with respect to the land of each layer is referred to as a hole center corresponding point, according to the circuit pattern design rule, the arc-shaped portion of the land contour is regarded as a part of a circular arc. In general, the center point of the arc is defined as the hole center corresponding point. And, when the position of the center point corresponding to the hole center on the front and back is misaligned in the circuit pattern formed on both the front and back surfaces of a circuit board etc., either one of them is formed, or a through hole or a via hole is formed at an intermediate position between the two. Will do.

However, the fine patterning often causes the positions of the lands on the front and back to be out of the standard range (that is, to the extent that it cannot be accommodated by the method of matching one side or the middle position). Significant defects such as chipping of lands and short-circuiting of unnecessary portions between layers occur. Also, in a multilayer circuit board or a single-sided circuit board, automatic insertion and assembly of electronic components is often performed by an NC device having two XY axes,
In this case, since the insertion position is determined by the numerical control data for controlling the NC device, it is necessary to manage the relative position between the reference point (usually a reference hole) of the substrate and the insertion hole provided on the land with high accuracy. That is, when the circuit pattern has a large displacement, an electronic component insertion error occurs.

[0005] As in the above-described example, it is important to inspect land displacement in a circuit pattern formed on the front and back of a circuit board or a circuit pattern of a multilayered circuit board, and to inspect a distance between a plurality of points of the circuit pattern. It is an issue.
Therefore, the following methods have been considered for inspecting the displacement of the land and the distance between a plurality of points of the circuit pattern. That is, JP-A-3-282303 discloses that an image of a circuit pattern is taken by an ITV camera, enlarged and displayed on a monitor television, and an operator operates a cursor such as a cross, a circle, or a rectangle into a land or hole pattern. A method is described in which the X and Y coordinates of the cursor at this time are read and the positional deviation of the corresponding point of the hole center is inspected.

In Japanese Patent Application Laid-Open No. 2-221975, a circuit pattern is picked up by an ITV camera, enlarged and displayed on a monitor television, and front and back land patterns are arranged on the center line of the screen displayed on the monitor television screen. There is described a method in which an operator operates so as to sequentially contact each other, and inspects a positional shift between the front and back sides based on a moving amount at that time. Further, as another method, there is a method in which three or more points are specified in the arc portion of the land contour line using a precision length measuring device, and the center of the land is calculated from the positions of these points.

[0007]

By the way, generally, when measuring the displacement of the wiring pattern formed on the front and back of the circuit board, except for a large displacement which can be seen at a glance, a through hole, a via hole, It is inspected in the process after forming holes such as insertion holes. However, if the land is judged to be out of the specified range after drilling, the already drilled circuit board must be discarded. Since it often occurs, the loss of the substrate material increases and the productivity decreases. In other words, it is desirable to inspect the displacement of the land in an upstream process before forming a hole in the land, so that when a defect occurs, it is possible to quickly correct the defect and stabilize the quality in a short time, Further, occurrence of defects can be reduced.

As described above, it is desirable to inspect the displacement of the land in an upstream process before forming a hole in the land. However, an exposure mask film, a substrate after exposure, a substrate after printing, a substrate after etching, There is no hole in the substrate before hole processing like this, and in order to inspect these circuit patterns, it is necessary to estimate and measure the hole center corresponding point based on the land pattern without holes. . Also,
Since the land pattern has a lead lead-in portion and a portion that increases the land area, and is often not geometrically simple, the hole center corresponding point cannot be simply estimated.

On the other hand, in the technique described in the above-mentioned publication, since the detection of the hole center corresponding point is performed manually by the operator visually, it is particularly necessary to detect a lead drawing portion or a portion where the land area is increased. No consideration has been given. Further, even when the center position is automatically calculated from a point on the contour of the land, a point is designated on the contour of the land, and a large number of calculation methods are used to deal with various land shapes. The task of selecting a calculation method suitable for the shape is required of the operator.

In addition, actual lands have various shapes, and it is difficult to limit the shapes of lands in a line that manufactures various types. Further, the shape of the land may be different for one circuit board. For example,
In the inspection of the positional deviation of the circuit pattern between the signal circuit and the power supply circuit formed on the front and back of the inner layer substrate of the multilayer circuit board, and the distance inspection between the land and the reference point (usually a reference hole) of the substrate, the land is also used. May differ in shape. In such a case, if a complicated operation such as the above-described designation of the measurement point or the calculation method by the operator is performed, the efficiency of the inspection work is significantly reduced. In order to solve this problem, a general-purpose hole center corresponding point detection method that can be commonly applied to various shapes, directions, and sizes of lands is required.

[0011] Further, since the high-density circuit pattern is miniaturized and the land size and the distance between pins are reduced, even a slight deviation of the corresponding point of the hole center may cause a defect such as a land break or an interlayer short. Therefore, high precision measurement of 10 μm or less is required for measuring the displacement of the circuit pattern. To achieve such high accuracy,
It is conceivable to increase the resolution of the imaging device that images the circuit pattern.However, if the resolution is increased, the field of view becomes narrower and only a part of the inspection target can be imaged. It is difficult to understand whether the inspection is performed or not, and it takes time to adjust the inspection target portion within the field of view of the imaging device, and the operation efficiency is reduced.
Conversely, the problem is not solved even if the work is performed so that the field of view of the imaging device matches the inspection target location. Therefore, it is required to secure the size of the field of view of the imaging device and to improve the detection accuracy.

Furthermore, there are variations in the shape of the circuit pattern due to exposure, variations in the edge of the circuit pattern caused by the chemical treatment called etching, and the like, and irregularities generally occur at the edges of the circuit pattern. For this reason, if the measurement of the point corresponding to the center of the hole is performed by using a minute portion (for example, one pixel) of the edge, the measurement accuracy is deteriorated. Therefore,
It is necessary to improve the accuracy by performing processing such as averaging the outline of the edge.

The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to obtain a hole center corresponding point by a common operation for various shapes, directions, and sizes of lands. By increasing the versatility and adopting simple processing procedures for image processing, high-speed processing is possible even with inexpensive hardware resources. An object of the present invention is to provide a circuit pattern inspection method and an inspection apparatus capable of performing highly accurate measurement in pixel units.

[0014]

According to a first aspect of the present invention, there is provided a circuit pattern inspection method for inspecting a displacement of a center position of a land in a circuit pattern based on an image obtained by capturing the circuit pattern. A first step of displaying the measurement reference point on the screen of the monitor device together with a measurement reference point serving as a reference for measuring the center position of the land, a second step of positioning the measurement reference point in the image of the land of interest, Predetermined plural detection points are set at equal intervals on straight lines in at least two directions different from each other as starting points, and whether or not each detection point overlaps a land until the land does not overlap at least one detection point A third process of repeating the process of determining whether or not the detection points on each straight line are increased by a predetermined distance, and that any of the detection points does not overlap the land. A fourth step of moving the measurement reference point in a direction in which the detection point overlaps the land, and determining whether or not the number of detection points which do not overlap the land after the movement of the measurement reference point in the fourth step becomes a predetermined number or more. The third step and the fourth step are repeated until at least one of the conditions is satisfied, and when the above condition is satisfied, the position of the measurement reference point is set as the hole center corresponding point corresponding to the center position of the land. 5 steps.

According to this configuration, the hole center corresponding point can be detected based on the land where no hole is formed, and can be used for lands of various shapes in general.
Moreover, since the procedure is simple, high-speed processing can be performed even with inexpensive hardware. In the invention of claim 2,
A partial measurement area extending over the contour line of the land is set using the hole center corresponding point obtained by the method of claim 1 as a reference position, and the position of the hole center corresponding point is determined based on the overlapping dimension between the partial measurement area and the land. to correct.

In this configuration, a partial measurement area is further set based on the hole center corresponding point obtained in pixel units according to the procedure of claim 1, and the information obtained from the partial measurement area is used to reduce Also, the position of the hole center corresponding point can be determined with high accuracy, and the detection accuracy of the hole center corresponding point can be increased. According to a third aspect of the present invention, in the second aspect, three or more partial measurement areas are provided.

According to this configuration, by providing three or more partial measurement areas, it is possible to correct each of the vertical and horizontal axes on the screen, so that the number of partial measurement areas can be increased. Then, the detection accuracy of the hole center corresponding point is further improved. In the invention according to claim 4, claim 3
In the present invention, the partial measurement area is a rectangle having sides orthogonal to the straight lines on which the detection points are arranged.

According to this configuration, since the partial measurement area is a rectangle having a side perpendicular to the direction connecting the detection point and the measurement reference point with the measurement reference point as the reference point, from the hole center corresponding point to the partial measurement area. Is simplified.
According to a fifth aspect of the present invention, in the second to fourth aspects of the present invention, the overlapping dimension is evaluated by measuring the area of the overlapping portion between the partial measurement area and the land.

In this configuration, by making the partial measurement area rectangular and measuring the area of the partial measurement area, the calculation for correcting the position of the hole center corresponding point based on the partial measurement area becomes easy. According to a sixth aspect of the present invention, in the third to fifth aspects, the position of the partial measurement area is determined based on the position of the detection point overlapping the land when the hole center corresponding point is obtained by the method of the first aspect. To determine.

According to this configuration, when the lead lead-in portion is formed on the land, the partial measurement area can be arranged avoiding the portion overlapping the lead lead-in portion, and the hole center obtained based on the partial measurement area can be obtained. The position accuracy of the corresponding point can be further improved. According to a seventh aspect of the present invention, in the second to fifth aspects of the present invention, the shape of the land is determined based on the positional relationship of the detection points which do not overlap the land when the hole center corresponding point is obtained by the method of the first aspect. Is determined, and the partial measurement area is determined in consideration of the shape of the identified land.

In this configuration, by identifying the land shapes first, the optimum number and arrangement of the partial measurement areas in each land shape can be determined, and the measurement accuracy of the correction value obtained from the partial measurement area is improved. be able to. According to an eighth aspect of the present invention, in the second to fifth aspects of the present invention, when the hole center corresponding point is obtained by the method of the first aspect, the circumference passing through the detection point located at an equal distance from the measurement center point. The shape of the land is identified by searching above or in the vicinity thereof, and the partial measurement area is determined in consideration of the shape of the identified land.

According to this configuration, the shape of the land can be more accurately recognized by searching on or near the circumference of a predetermined radius in the state where the hole center corresponding point is obtained. In addition, the partial measurement area can be set more accurately by improving the identification accuracy of the land shape. The invention of claims 9 to 14 relates to a circuit pattern inspection apparatus. In the invention of claim 9, the positional deviation between the circuit patterns formed on the front and back surfaces of the inspection target is determined by the positional relationship of the lands in the front and back circuit patterns. An apparatus for inspecting based on the image, an imaging apparatus for imaging the front and back circuit patterns, and a monitor apparatus for displaying a measurement reference point serving as a reference for measuring the image of the imaged circuit pattern and the center position of the land. A plurality of predetermined detection points are set at equal intervals on straight lines in at least two directions different from each other starting from a measurement reference point located in a land to be measured. If the land overlaps at least one detection point, A detection point that repeats the process of determining whether each detection point overlaps a land and increasing the interval between the detection points on each straight line by a predetermined distance until the detection points disappear. Positioning means; positioning means for moving the measurement reference point relative to the land in such a direction that the detection point overlaps the land when any of the detection points does not overlap the land; and movement of the measurement reference point. Later, the detection point setting means and the positioning means are alternately operated until at least one of the conditions that the number of detection points that do not overlap the land is equal to or more than a predetermined number or has a specific positional relationship is satisfied, and the above conditions are satisfied. And a center determining means for determining the position of the measurement reference point as a hole center corresponding point corresponding to the center position of the land, and determining the hole center corresponding point for each land of interest of the circuit pattern on the front and back, and then determining between the hole center corresponding points. A comparison / determination unit that determines a non-defective product when the distance obtained by comparing the distance with the reference value is within the reference value.

According to the ninth aspect of the present invention, the hole center corresponding point is obtained for each of the land patterns corresponding on the front and back surfaces, and the difference between them is obtained, thereby displacing the position of the circuit pattern on the front and back surfaces with respect to various lands. General-purpose measurement, and high-precision measurement is possible with inexpensive hardware. According to a tenth aspect of the present invention, there is provided an apparatus for inspecting a distance between a plurality of points of a circuit pattern formed on an inspection target based on a positional relationship between lands in the circuit pattern, and an imaging apparatus for imaging the circuit pattern, A monitor device for displaying an image of the circuit pattern and a measurement reference point serving as a reference for measuring the center position of the land, and a monitor device on a straight line in at least two directions different from each other starting from the measurement reference point located in the land of interest A plurality of predetermined detection points are set at the same interval, and it is determined whether or not each detection point overlaps the land until the land does not overlap with at least one detection point. A detection point setting means for repeating a process of increasing the interval by a predetermined distance, and a direction for overlapping the detection point with the land when any of the detection points does not overlap with the land Positioning means for moving the measurement reference point relative to the land, and at least one condition of whether the number of detection points that do not overlap the land after the movement of the measurement reference point is equal to or more than a predetermined number or has a specific positional relationship is A center determining unit that operates the detection point setting unit and the positioning unit alternately until the condition is satisfied, and sets the position of the measurement reference point as a hole center corresponding point corresponding to the center position of the land when the above condition is satisfied; And comparing and determining a distance between the hole center corresponding points for each of the plurality of lands to be compared with a reference value, and determining that the determined distance is within the reference value to determine a non-defective product. .

According to the tenth aspect of the present invention, the distance (pitch) between the plurality of points on the circuit pattern can be determined for each of the plurality of lands by determining the hole center corresponding points for the plurality of lands and calculating the difference therebetween. Can be measured versatile, and highly accurate measurement can be performed with inexpensive hardware. According to an eleventh aspect of the present invention, in the ninth or tenth aspect of the present invention, a partial measurement area extending over the contour of the land is set based on the position of the hole center corresponding point and the information on the detected point. Center position determining means for correcting the position of the hole center corresponding point based on the overlap dimension between the hole and the land.

With this configuration, the reference measurement point obtained in pixel units can be corrected using the information of the partial measurement area, and the detection accuracy of the hole center corresponding point can be improved. In the twelfth aspect, the ninth to the first aspects
In the first aspect of the present invention, the measurement reference point is displayed at a fixed position in the screen of the monitor device, and the land of interest is overlapped with the measurement reference point by moving the inspection target.

In this configuration, by moving the object to be inspected and overlapping it with the measurement reference point, the moving mechanism can be simplified and practically easy to use. In particular, when the operator holds and moves the inspection object by hand, a moving mechanism can be dispensed with, and an inspection apparatus that is inexpensive and easy in alignment and has high workability can be provided. In the invention according to claim 13, the first imaging device and the second imaging device which are fixed to a fixed position with respect to the inspection target and respectively image circuit patterns at corresponding positions on the front and back surfaces of the inspection target, 9. A third image pickup device which is relatively movable and picks up another position of the circuit pattern, and a hole center corresponding point of a land in the circuit pattern picked up by each image pickup device. Image processing means for measuring the position of the circuit pattern by obtaining using the method described above, and a hole obtained by the image processing means for determining whether or not the position of the circuit pattern on the front and back surfaces of the inspection target and the distance between a plurality of points of the circuit pattern are good Calculation determining means for determining based on the positional relationship of the center corresponding points.

According to this configuration, it is possible to simultaneously capture images used for the positional deviation inspection of the circuit pattern on the front and back surfaces and the distance inspection between a plurality of points of the circuit pattern, so that the inspection speed can be increased. According to a fourteenth aspect, in the thirteenth aspect, a position measuring means for measuring a moving distance of the third imaging means is added.

According to this configuration, it is possible to perform the distance inspection by the inspection apparatus alone without using the reference object.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a flow chart showing the processing procedure of the inspection method of the present invention. FIGS. 2 to 5 show the case where the inspection method of the present invention detects a hole center corresponding point for lands of various shapes. 4 shows a changing process of a relationship between a land and a detection point. In the present invention, first, a circuit pattern formed on a mask film for exposure or a circuit board is imaged by TV cameras 1a to 1c (see FIG. 13) as image pickup devices, and an image of the circuit pattern and a center position of a land are measured. The reference measurement reference point is displayed on the screen of the monitor device 2 (see FIG. 13) (S1 in FIG. 1). The display magnification of the monitor device 2 is 2
0 to 30 times is appropriate. Either one of the circuit patterns and the measurement reference points may be displayed first, or they may be displayed simultaneously. The measurement reference point may have any shape as long as it can indicate the position, such as a point or a cross mark. For example, a circuit board T (FIG. 1)
3), the image of the circuit pattern S captured by each of the TV cameras 1a and 1b is displayed on the screen of the monitor device 2. Is displayed together with the measurement reference point P _{0 in the} form as shown in FIG.

Next, in order to indicate a land L to be inspected from among the circuit patterns S displayed on the screen of the monitor device 2, a measurement reference point P _{0 is} set in an area inside the land L to be inspected. Are superimposed (S2 in FIG. 1). Land L
In order to overlap the measurement reference point P ₀ with the measurement reference point P ₀ , the land L may be moved (that is, the circuit pattern S is moved relative to the screen), or the measurement reference point P ₀ may be overlapped. The point P ₀ may be moved with respect to the land L (that is, the measurement reference point P ₀ may be moved on the screen). For the movement of the land L, the inspection target on which the circuit pattern is formed may be moved, or the TV that is imaging the inspection target may be moved.
The cameras 1a and 1b may be moved (the members surrounded by broken lines in FIG. 13 except for the circuit board T are integrally moved).

[0031] After the superposition of reference point P ₀ in the inner area of the land L to be inspected, as shown in (a) of FIG. 2 to FIG. 5, eight directions which starting from the reference point P ₀ equal intervals to set the detection point P ₁ of each predetermined plurality on a straight line (S3 in Fig. 1). Distance detection point P ₁ is is set the same in any straight line. Each straight line is set at equal angular intervals of every 45 degrees around the reference point P _0.
Here, although setting the detection point P ₁ in the eight directions of a straight line, it is possible to achieve the object as long as two lines or more different directions. Each detection point P ₁ is provided for the purpose of determining the overlap with the land L. It is determined whether each detection point P ₁ overlaps the land L (S4 in FIG. 1), and all the detection points P ₁ are determined. Overlaps the land L (S in FIG. 1).
5), the distance between the detection point P ₁ on the straight line is increased (S6 in FIG. 1) repeats the processing of steps S3 to S6.

[0032] In step S5, when the at least one detection point P ₁ is determined to no longer overlap the land L, and the measurement reference point P ₀ in the direction of superimposing the detection point P ₁ that does not overlap the land L to the land L mobile (S7 in FIG. 1).
That is, the state is as shown in FIG. Here, the direction in which the measurement reference point P ₀ is moved is a direction from the detection point P ₁ that does not overlap the land L to the measurement reference point P ₀ . However, when the detection point P ₁ at the same time for a plurality of directions are no longer overlap with the lands L may be employed an intermediate direction of respective directions. The amount of movement of the reference point P ₀ is also performed in units of pixels, and may be performed in plurality of pixels, which is determined according to the test time and the detection accuracy.

Next, determine at least one of the detection point P ₁ that does not overlap the land L after moving the reference point P _0, the number and positional relationship (arrangement pattern). Here, if the determination condition is not satisfied, the above operation is repeated (see FIGS. 2 to 5C), and if at least one of the condition that the number is equal to or more than a predetermined number and the positional relationship is a specific pattern is satisfied. (see FIG. 2 (d) to FIG. 5), the hole center corresponding point reference point P ₀ at that time (S9 in FIG. 1). At least one condition means that only one of the conditions may be used as the determination condition, or both may be used as the determination conditions. If the condition is satisfied, repeat the steps S3~S7 until the conditions are met by increasing the distance between the detection point P ₁ (Fig. 1
S8). 2 and 3 show patterns of the land L used in the signal circuit, and FIGS. 4 and 5 show patterns of the land L used in the power supply circuit.

The hole center corresponding point measured by the above-described method is obtained in units of one pixel. Here, the following method is employed to improve the measurement accuracy of the hole center corresponding point to the sub-pixel accuracy regardless of the resolution of the TV cameras 1a and 1b. Now, from P ₁₁ in FIG.
Shall P ₁₈ is a detection point when the determined hole center corresponding points 'coordinates on the screen of the monitor device 2 (X0' hole center corresponding point P ₂ obtained by the method described above, Y
0 ').

First, noting that only the detection point P ₁₃ overlapping the land L when the hole center corresponding point P ₂ ′ is obtained, in the direction from the hole center corresponding point P ₂ ′ to the detection point P ₁₃ . It is estimated that there is a lead pull-in part. Generally, the lead lead-in portion protrudes outside the circle centered on the hole center corresponding point P ₂ ′, and is not suitable for use in determining the true hole center corresponding point P ₂ . Therefore, based on the hole center corresponding point P ₂ ′, the direction to the detection point P ₁₇ opposite to the detection point P ₁₃ and the hole center corresponding point P 2
Detection point P ₁₁ is the direction perpendicular to the direction of the detection point P ₁₇ from ₂ ', selects the direction to P _15. Next, in each direction from the hole center corresponding point P ₂ ′ toward the detection points P ₁₇ , P ₁₁ , and P ₁₅ , the size of p × q pixels is respectively set at a position at a fixed distance D from the hole center corresponding point P ₂ ′. The rectangular partial measurement areas A, B1, and B2 are set. Here, the size of the distance D is set to a size in which the partial measurement areas A, B1, and B2 straddle the contour of the land L.

Next, the area (the number of pixels) of the portion overlapping the land L in each of the partial measurement areas A, B1, B2 is measured. Each partial measurement area A, B1, B2 respect of the determined area of the respective a, b1, b2, true hole around the corresponding point of P ₂ coordinates (hereinafter hole center corresponding points after correction obtained by the treatment) (X0 , and Y0), further portions measurement area from the true hole center corresponding point P ₂ a, B1, B2
Assuming that the average distance to the contour line of the land L in R is R, these have the following relationship. R = D + (b1 + b2) / 2p ΔX = R− (D + a / p) = − (2a−b1−b2) / 2p ΔY = (b1−b2) / 2p X0 = X0 ′ + ΔX = X0 ′ − (2a −b1−b2) / 2p Y0 = Y0 ′ + ΔY = Y0 ′ + (b1−b2) / 2p where ΔX and ΔY are the hole center corresponding point P ₂ ′ obtained by the processing procedure of FIG. 1 and the true hole center. which is an error of a corresponding point P _2. FIG. 8 shows the positional relationship between the hole center corresponding point P ₂ ′ obtained by the procedure shown in FIG. 1 and the corrected hole center point P ₂ .

In the above embodiment, an example is shown in which the lead lead portion is located on the right side of the land L. However, the present method can be applied regardless of the direction in which the lead lead portion is located on the land L. For example, as shown in FIG. 9, when the present method is applied to a land L having a lead lead portion in a direction forming an angle θ with respect to the X direction in the embodiment described with reference to FIG.

That is, the arrangement of the partial measurement areas A, B1, and B2 is determined by the above-described method. The shape and size of each of the partial measurement areas A, B1, and B2 are the same as in the above-described example. Here, the areas of the partial measurement areas A, B1, and B2 that overlap the land L are a, b1, and b2, respectively. At this time, the XY coordinate and T-
If the U coordinate is imagined, the TU coordinate can be handled in the same manner as in the above example, so that ΔT = − (2a−b1−b2) / 2p ΔU = (b1−b2) / 2p. Then, if the TU coordinates are converted to the XY coordinates, the following relationship is obtained. ΔX = Δb1 (cosθ−sinθ) + b2 (sinθ + cosθ)
−2a cos θ｝ / 2p ΔY = Δb1 (sin θ + cos θ) + b2 (sin θ−cos θ)
−2a sinθ｝ / 2p X0 = X0 ′ + ΔX = X0 ′ + Δb1 (cosθ−sinθ) + b2 (sinθ + cos
θ) -2a cos θ｝ / 2p Y0 = Y0 ′ + △ Y = Y0 ′ + ｛b1 (sinθ + cosθ) + b2 (sinθ−cos
θ) -2a sin θ｝ / 2p For example, when the angle θ is 45 degrees, the relationship of Expression 1 is satisfied.

[0039]

(Equation 1)

In the example described above, the hole center corresponding point P ₂ ′
The reference point P ₀ in the three directions of the straight line determined based on the information of the detection point P ₁₃ that overlaps the land L when determined
At a fixed distance D from the measurement reference point P ₀ and each detection point P
_11, the area of the portion overlapping the land L in P _15, provided rectangle having a side perpendicular to the direction connecting the P ₁₇ partial measurements areas A, B1, B2, respectively, partial measurement area A, B1, B2 Is measured, the hole center corresponding point P ₂
Is measured in detail with high precision in units of sub-pixels (0.1 pixels).

FIG. 10 shows partial measurement areas A, A1, A2, B1, B2, B3, B4, C, and C for various lands L.
The example of arrangement | positioning of D1 and D2 is shown. As described above, the partial measurement areas A, A1, A2, B1, B2, B3, B4, C, D1, and the like are determined according to the shape of the land L and the position of the lead lead-in portion.
Various arrangements of D2 are conceivable. Also, as shown in FIG. 10, the partial measurement areas A, A1, A2, B1, B2, B
3, B4, C, D1, and D2 are not limited to three locations. For example, if one location is selected, the hole center corresponding point is determined based on the curvature change of the contour of the land L in the partial measurement area. it is also possible to determine the P _2. However,
In order to increase the correction accuracy for the two axes X and Y, three or more settings are desirable. Further, the shape of the partial measurement area may be a circle, a triangle, or a trapezoid, but the calculation can be simplified by making it a rectangle.

In the measurement of the dimension of the land L in the partial measurement area, it is not always necessary to use the area, but the density is used, or a plurality of lines are set on the land L and directly measured on the line. The values may be averaged. Also, the dimension measurement of the land L can be performed by directly measuring the land L portion.
The measurement may be performed indirectly from a portion other than the land L (that is, the dimensions of the portion other than the land L may be measured in the partial measurement area and subtracted from the dimensions of the partial measurement area).

Further, in this embodiment, when the hole center corresponding point P ₂ ′ is obtained, the arrangement of the partial measurement area is determined from the information of the detection point P ₁₃ overlapping the land L. based on the detection pattern of the presence or absence of an overlap between the land L in the detection point P ₁₁ to P ₁₈ when seeking ₂ 'to identify the shape of the land L, thereby it may be determined arrangement of portions measurement area.

For example, a land L and a detection point P₁Figure 2
5 to (d) of FIG.
(A) (c) (e) (g)
it can. The recognition of the shape of the land L is based on the point P corresponding to the hole center.
_Two'When measuring'₀Predetermined half centered on
Searching on or near the circumference of the diameter
Can also be. If this method is adopted, the shape of the land L can be changed.
Recognition can be performed with higher accuracy and partial measurement
Since the rear can be properly arranged, the center point P of the hole center _TwoSpirit of
The degree improves. Now, FIGS. 11 (a) and 12 (a)
Partial measurement areas A, B1,
The example which determines B2 is shown. In this case, each detection point P₁₁~ P
₁₈And the pattern of overlap between the land L
FIG. 11 shows the partial measurement areas A, B1, and B2.
(A), (b), and arrangements as shown in FIGS.
Can be FIGS. 11B and 12B correspond to the center of the hole.
Point P_TwoMeasurement at four locations to improve measurement accuracy
Areas A1, A2, B1, and B2 are provided. But
In FIG. 12B, the detection point P₁₂, P₁₄Compatible with
The partial measurement areas A1 and B2 provided by
Since the contour lines include parts that are not on the circumference,
Including such a portion deteriorates the accuracy of position measurement. So
Here, in order to avoid such an arrangement, FIG.
As shown in FIG. 12 and FIG._Two′
Measurement reference point P when₀Not around the circumference
To set a search line K in the vicinity of the search
And the detection point P₁₂, P₁₃, P₁₄Of the contour of the land L between
Information about the shape can be obtained, and FIG.
12 (a) can be recognized.
You. By recognizing the shape of the land L in this way,
If the shape is recognized as shown in FIG.
The arrangement shown in FIG.
If the shape is recognized as shown in FIG. 12A, the arrangement shown in FIG.
The contour of the land L in the partial measurement area
Arrangements that include parts can be avoided.

FIG. 13 shows a configuration example of an apparatus for realizing the above method. In FIG. 13, a circuit board T to be inspected,
The parts holding the TV cameras 1a, 1b, 1c, the mirror 3, the moving table 4, and the linear scale 5 are omitted.
As shown in the figure, three TV cameras 1a are used as imaging devices.
1c, the front surface of the circuit board T is imaged by the TV camera 1a, and the back surface of the circuit board T is imaged by the TV camera 1b via the mirror 3 for image inversion. In addition, a T which captures an image of a different position on the circuit board T from the TV cameras 1a and 1b.
A V camera 1c is provided, and the TV camera 1c is movable by a moving table 4 in a direction along the surface of the circuit board T. The position of the TV camera 1c is detected by a linear scale 5 as a position measuring means.

The image detecting section 11 has TV cameras 1a to 1c.
The image signal picked up at is input and the image signal is stored. The image selection unit 12 selects an image to be subjected to image processing from images captured by the TV cameras 1a to 1c. The selected image is combined with the measurement reference point P ₀ in the image processing unit 13, and the combined image is displayed on the screen of the monitor device 2. Here, the alignment between the measurement reference point P ₀ and the land L to be inspected is performed by moving the circuit board T. Also, the hole center corresponding point P ₂ ′
Is determined by applying the above method. That is, the image processing unit 13 is an image processing unit, and includes a detection point setting unit, a positioning unit, and a center determining unit.

The arithmetic processing section 14 calculates the distance between the hole center corresponding point P ₂ ′ obtained as described above for the front and back lands L of the circuit board T. After that, the comparison / determination unit 15 compares the distance obtained by the arithmetic processing unit 14 with the reference value to determine the quality. That is, the arithmetic processing unit 14 and the comparison / determination unit 15 constitute an arithmetic determination unit. The inspection result output unit 16 outputs the inspection result obtained by the comparison / determination unit 15 to a printer or the like. To further improve the measurement accuracy, determined with sub-pixel accuracy the location of the true hole center corresponding point P ₂ using the method described above on the basis of the hole center corresponding point P ₂ ', for the hole center corresponding point P ₂ The pass / fail judgment may be performed by the same processing.

Here, the corresponding lands L are imaged on the front and back surfaces of the circuit board T by the TV cameras 1a and 1b, and the images are input to the image detecting section 11. If this apparatus is used, the circuit patterns on both the front and back surfaces are shifted. An inspection can be performed. Also, a TV camera 1a or a TV camera 1b,
The land L in the same plane or on a different plane of the circuit board T is imaged by the TV camera 1c, and the image is
If the input is 1, the apparatus can inspect the distance (pitch) between a plurality of points of the circuit pattern. In this case, the TV
The moving distance of the camera 1c is measured by the linear scale 5, the value is added to the measured value of the displacement by image processing to calculate the distance between a plurality of points of the circuit pattern, and this distance is compared with a reference value. If the distance is within the reference value, it may be determined that the product is good. The distance between a plurality of points of the circuit pattern may be measured by calculating the positions of two lands L in one screen by using the same method, or by moving the TV camera 1c. The measurement may be performed by obtaining the positions of the two lands L imaged by the same method. If the optical system is changed, the displacement of the land L of the circuit pattern on the front and back of the circuit board T can be reduced by one.
It is also possible to measure with a single TV camera.

[0049]

According to the first aspect of the present invention, the center corresponding to the hole can be detected on the basis of the land on which no hole is formed, and the invention can be generally used for lands having various shapes. . Moreover, since the procedure is simple, there is an advantage that inexpensive hardware can be processed at high speed.

According to a second aspect of the present invention, a partial measurement area is further set based on the hole center corresponding point obtained in pixel units by the procedure of the first aspect, and information obtained from the partial measurement area is used. There is an advantage that the position of the hole center corresponding point can be corrected with higher accuracy than the unit, and the detection accuracy of the hole center corresponding point increases. According to the third aspect of the invention, by providing three or more partial measurement areas, it is possible to correct each of the vertical axis and the horizontal axis on the screen. There is an effect that the detection accuracy of the center corresponding point is further improved.

According to the fourth aspect of the present invention, the partial measurement area is a rectangle having sides perpendicular to the direction connecting the detection point and the measurement reference point with the measurement reference point as the reference point. There is an advantage that the calculation of the distance to is simplified. According to the fifth aspect of the present invention, since the partial measurement area is rectangular and the area of the partial measurement area is measured, there is an advantage that the calculation for correcting the position of the hole center corresponding point based on the partial measurement area becomes easy. .

According to a sixth aspect of the present invention, when a lead lead-in portion is formed on a land, a partial measurement area can be arranged avoiding a portion overlapping with the lead lead-in portion, and a hole obtained based on the partial measurement area can be provided. There is an advantage that the positional accuracy of the center corresponding point can be further improved. According to the invention of claim 7, by identifying the land shapes first, the optimum number and arrangement of the partial measurement areas in each land shape can be determined, and the measurement accuracy of the correction value obtained from the partial measurement area is improved. There is an advantage that can be.

According to an eighth aspect of the present invention, the shape of the land can be recognized more accurately by searching on or near the circumference of a predetermined radius in the state where the hole center corresponding point has been obtained. Therefore, there is an advantage that the identification accuracy of the land shape can be improved and the partial measurement area can be set more accurately. According to a ninth aspect of the present invention, a hole center corresponding point is obtained for each of the corresponding land patterns on both the front and back surfaces, and the difference between the hole center and the land pattern is obtained, so that the misalignment of the circuit pattern on the front and back surfaces can be measured for various lands in general. There is an advantage that high-precision measurement can be performed with inexpensive hardware.

According to a tenth aspect of the present invention, a distance (pitch) between a plurality of points on a circuit pattern is obtained by obtaining a hole center corresponding point for each of a plurality of lands and obtaining a difference therebetween.
Can be universally measured for various lands,
Moreover, there is an advantage that highly accurate measurement can be performed with inexpensive hardware. The invention of claim 11 has the advantage that the reference measurement point obtained in pixel units can be corrected using the information of the partial measurement area, and the detection accuracy of the hole center corresponding point can be improved.

According to the twelfth aspect of the present invention, the inspection object is moved and overlapped with the measurement reference point, so that the movement mechanism can be simplified and practically easy to use. In particular, when the operator holds and moves the inspection object by hand, a moving mechanism can be dispensed with, and there is an advantage that an inexpensive and easily operable inspection apparatus can be provided.

According to the thirteenth aspect of the present invention, it is possible to simultaneously capture images used for the inspection of the positional deviation of the circuit pattern on the front and back surfaces and the inspection of the distance between a plurality of points of the circuit pattern.
There is an advantage that the inspection speed can be increased. Claim 1
The invention of the fourth aspect has an advantage that the distance inspection can be performed by the inspection apparatus alone without using the reference object.

[Brief description of the drawings]

FIG. 1 is an operation explanatory diagram showing a processing procedure of an embodiment.

FIG. 2 is an operation explanatory diagram of the embodiment.

FIG. 3 is an operation explanatory diagram of the embodiment.

FIG. 4 is an operation explanatory diagram of the embodiment.

FIG. 5 is an operation explanatory diagram of the embodiment.

FIG. 6 is a diagram illustrating an example of a relationship between a circuit pattern and a measurement reference point in the embodiment.

FIG. 7 is a diagram illustrating a setting example of a partial measurement area in the embodiment.

FIG. 8 is a diagram showing a concept of correcting a hole center corresponding point using a partial measurement area in the embodiment.

FIG. 9 is a diagram illustrating an example of setting a partial measurement area on a land inclined with respect to a basic axis of a screen in the embodiment.

FIG. 10 is a diagram illustrating an example of setting partial measurement areas for various lands according to the embodiment.

FIG. 11 is a diagram illustrating a concept of recognizing a land shape using a search line according to the embodiment.

FIG. 12 is a diagram illustrating a concept of recognizing a land shape using a search line in the embodiment.

FIG. 13 is a block diagram illustrating an inspection apparatus used in the embodiment.

[Explanation of symbols]

1a TV camera 1b TV camera 1c TV camera 2 Monitoring device 5 Linear scale 11 Image detection unit 12 Image selection unit 13 Image processing unit 14 Operation processing unit 15 Comparison / judgment unit 16 Inspection result output unit A Partial measurement area B1 Partial measurement area B2 Partial measurement area K search line L land P ₀ measurement reference point P ₁ detection point P ₂ hole center corresponding point P ₂ ′ hole center corresponding point P _{11 to} P ₁₈ detection point

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01B 11/00 G01B 11/24 G01N 21/88 H05K 3/00

Claims (14)

(57) [Claims] 1. A circuit pattern inspection method for inspecting a displacement of a center position of a land in a circuit pattern based on an image obtained by capturing a circuit pattern, the measurement serving as a reference for measuring the center position of the land. A first step of displaying on the screen of the monitor device together with the reference point, a second step of locating the measurement reference point within the image of the land of interest, and a straight line in at least two different directions starting from the measurement reference point A predetermined number of detection points are set at the same intervals, and it is determined whether or not each detection point overlaps the land until the land does not overlap with at least one detection point, and the detection on each straight line is performed. A third process of repeating the process of increasing the interval between points by a predetermined distance; and, when any of the detection points no longer overlaps the land, the detection point is overlapped with the land. To move the measurement reference point
And a third step and a fourth step until at least one of a condition that the number of detection points that do not overlap the land after the movement of the measurement reference point in the fourth step becomes a predetermined number or has a specific positional relationship is satisfied. And a fifth step of, when the above condition is satisfied, setting the position of the measurement reference point as the hole center corresponding point corresponding to the center position of the land. 2. A partial measurement area extending over a contour line of a land is set using the hole center corresponding point obtained by the method of claim 1 as a reference position, and the hole center is determined based on the overlapping dimension of the partial measurement area and the land. A circuit pattern inspection method, wherein the position of a corresponding point is corrected. 3. The circuit pattern inspection method according to claim 2, wherein three or more partial measurement areas are provided. 4. The circuit pattern inspection method according to claim 3, wherein the partial measurement area is a rectangle having a side orthogonal to each of the straight lines on which the detection points are arranged. 5. The circuit pattern inspection method according to claim 2, wherein an overlapping dimension is evaluated by measuring an area of an overlapping portion between the partial measurement area and the land. 6. The position of the partial measurement area is determined based on the position of the detection point overlapping the land when the hole center corresponding point is obtained by the method of claim 1. Item 6. The circuit pattern inspection method according to Item 5. 7. A land shape is identified based on a positional relationship of detection points that do not overlap with a land when the hole center corresponding point is obtained by the method of claim 1, and the shape of the identified land is taken into account. 6. The circuit pattern inspection method according to claim 2, wherein a partial measurement area is determined. 8. A land shape is identified by searching for a circle passing through a detection point located equidistant from the measurement center point or its vicinity when the hole center corresponding point is obtained by the method of claim 1. 6. The circuit pattern inspection method according to claim 2, wherein the partial measurement area is determined in consideration of the shape of the identified land. 9. An imaging device for inspecting a positional shift between circuit patterns formed on both front and back surfaces of an inspection target based on a positional relationship between lands in the front and back circuit patterns, and an imaging device for imaging the front and back circuit patterns, respectively. And a monitor device for displaying a captured image of the circuit pattern and a measurement reference point serving as a reference for measuring the center position of the land, and at least two directions different from each other starting from the measurement reference point located in the land of interest. A plurality of predetermined detection points are set on the straight line at the same interval, and it is determined whether or not each detection point overlaps the land until the land does not overlap with at least one detection point. Detecting point setting means for repeating the process of increasing the interval between the detecting points by a predetermined distance, and setting the detecting point to a land when any of the detecting points does not overlap the land. Positioning means for moving the measurement reference point relative to the land in a direction in which the detection reference point does not overlap the land after the movement of the measurement reference point. The detection point setting means and the positioning means are alternately operated until at least one of the conditions is satisfied, and when the above condition is satisfied, the position of the measurement reference point is set as the hole center corresponding point corresponding to the center position of the land. The center determining means and, for each land of interest of the front and back circuit patterns, determine the hole center corresponding point, then determine the distance between the hole center corresponding points, compare with the reference value, and determine that the distance is within the reference value. A circuit pattern inspection apparatus, comprising: a comparison determination unit for determining. 10. An apparatus for inspecting a distance between a plurality of points of a circuit pattern formed on an inspection target based on a positional relationship between lands in the circuit pattern, comprising: an imaging apparatus for imaging the circuit pattern; And a monitor device for displaying a measurement reference point serving as a reference for measuring the center position of the land, and the same intervals on straight lines in at least two different directions starting from the measurement reference point located in the land of interest In the above, a predetermined plurality of detection points are set, and it is determined whether or not each detection point overlaps the land until the land does not overlap with at least one detection point, and the interval between the detection points on each straight line is determined. Detecting point setting means for repeating a process of increasing the distance by a predetermined distance, and a measuring base in a direction in which the detecting point overlaps the land when any of the detecting points does not overlap the land. Positioning means for moving the reference point relative to the land, and at least one of the following conditions: at least a predetermined number of detection points that do not overlap the land after the movement of the measurement reference point or a specific positional relationship is satisfied. The detection point setting means and the positioning means are alternately operated until the above condition is satisfied, and when the above condition is satisfied, the position of the measurement reference point is set as the hole center corresponding point corresponding to the center position of the land. Comparing the distance between the hole center corresponding points for each of a plurality of lands, and then comparing the distance between the hole center corresponding points with a reference value, and determining that the obtained distance is within the reference value to determine a non-defective product. A circuit pattern inspection apparatus, characterized in that: 11. A partial measurement area extending over a contour line of a land is set from the information on the position of the hole center corresponding point and the detected point, and the hole center corresponding point is determined based on the overlapping dimension between the partial measurement area and the land. The circuit pattern inspection apparatus according to claim 9, further comprising a center position determination unit that corrects the position of the circuit pattern. 12. The method according to claim 9, wherein a measurement reference point is displayed at a fixed position in a screen of the monitor device, and a land of interest is superimposed on the measurement reference point by moving an inspection target. Circuit pattern inspection equipment. 13. A first image pickup device and a second image pickup device which are fixed to a fixed position with respect to an inspection target and respectively image circuit patterns at corresponding positions on the front and back surfaces of the inspection target, and are relatively positioned with respect to the inspection target. 9. A method according to claim 1, further comprising the steps of: a third imaging device which is movable in a movable manner and images another position of the circuit pattern; and a point corresponding to a hole center of a land in the circuit pattern imaged by each imaging device. Image processing means for measuring the position of the circuit pattern by determining the position of the circuit pattern on the front and back surfaces of the inspection target and the hole center corresponding to the distance between a plurality of points of the circuit pattern by the image processing means. An inspection apparatus for a circuit pattern, comprising: an operation determination unit that determines based on a positional relationship between points. 14. The circuit pattern inspection apparatus according to claim 13, further comprising a position measuring means for measuring a moving distance of the third imaging means.