JPH0777417A - X-ray image pickup method and board machining method therewith - Google Patents

Abstract

PURPOSE:To simply calculate the minimum amount required X-ray radiation and automatically set X-ray radiation conditions by adding transmission images in sequence for image processing, and comparing the image processed result of the added image with the previous one. CONSTITUTION:When a printed board is fed on a table, a command is sent to an X-ray radiating means 14 from a CPU 15, and the first X-ray radiation is performed to the identification mark of the board. The X-ray transmission image of the board reaches an X-ray camera 5, an image picked up by the camera 5 is fed to an image input device 16 by the command of the CPU 15, it is stored in an image memory device 17 after A/D conversion, and the center position of an identification pattern is calculated. X-ray radiation is repeated, the X-ray transmission images obtained by the camera 5 and the device 16 are added in sequence to the image at the time of the previous radiation stored in the device 17, and the center position of the identification mark is calculated from the added images. The coordinates of the detected center point are gradually made correct when the X-ray radiation is repeated in sequence.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray imaging method and a substrate processing method using the same.

[0002]

2. Description of the Related Art Conventionally, in a printed circuit board or the like, when a reference hole for punching a press or mounting an electric component is formed, an identification pattern (mark) is formed at the same time as a conduction pattern
Is formed, and a hole is made at this identification pattern position. When a multi-layer printed circuit board is used and an identification pattern is present in the inner layer, the identification pattern is not exposed to the outside, and therefore it cannot be identified by visible light. An X-ray transmission image of the identification mark is obtained using an X-ray irradiation device. A configuration using an image pickup device that picks up an image of the object and detects the pattern position based on the image is often adopted.

[0003]

In the above configuration,
In order to detect the position of the identification pattern as accurately as possible, it is desirable to increase the amount of X-rays to be emitted. However, when the amount of X-rays is increased, the irradiation time naturally becomes longer, the processing efficiency is lowered, and the processing cost is increased.
Therefore, it is required to perform the minimum necessary X-ray irradiation while maintaining the positioning accuracy.

For this reason, conventionally, a work is continuously irradiated with X-rays and an image processed image is displayed on a display, and the X-ray irradiation is stopped when the user always looks at the image and determines that the noise is gone. ing. However, this method relies heavily on the visual inspection of the user, which complicates the work and makes automation difficult.

Therefore, an object of the present invention is to obtain the minimum X-ray dose necessary for accurate image processing by calculation, not by user's visual observation, and automatically set the X-ray irradiation process accordingly. It is in.

[0006]

In order to achieve the above object, an X-ray imaging method of the present invention uses an X-ray irradiating means for irradiating an X-ray and an X-ray irradiating a work from the X-ray irradiating means. An X-ray irradiating unit performs X-ray irradiation on a specific work by using an image pickup unit that picks up a transmission image and an image processing unit that performs image processing based on a picked-up result by the image pickup unit. The transmission image is image-processed each time it is increased by a fixed amount, and compared with the image processing result up to the previous time, X at the time when the variation in the image processing result converges within a predetermined range.
The amount of X-ray irradiation is set as the required amount of irradiation, and when the work is imaged thereafter, the required amount of X-ray irradiation is performed and image processing is performed based on that.

Specifically, the X-ray irradiating means irradiates a predetermined amount of X-rays by one operation, and the X-ray irradiating means repeatedly irradiates a specific work.
The transparent images obtained each time are sequentially added, image processing is performed on the added images, and the image processing results based on the added images up to the previous time are compared, and variations in the image processing results converge within a predetermined range. The number of times of X-ray irradiation at that time is set as the required number of times of irradiation, and when the work is imaged thereafter, X-ray irradiation of the necessary number of times of irradiation is performed and image processing is performed based on the added image. To do so.

More specifically, X times n times (n is a natural number)
A calculated value obtained based on the line irradiation addition image, and (n-1)
The difference from the calculated value obtained based on the X-ray irradiation addition image for one time is calculated, and when the absolute value of this difference falls within the predetermined range, the n is set as the necessary irradiation number of times.

The substrate processing method according to the present invention uses a substrate on which a pattern is formed in advance as a work, and
The position of the pattern of the work is detected using a line imaging method, and the substrate is processed based on the result of this pattern position detection.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a substrate punching device used in this embodiment. An XY table mechanism 3, a perforating means 4 and an X-ray camera (imaging means) 5 which are moved by the XY table mechanism 3, are provided below a table 2 on which a printed circuit board 1 as a work to be processed is placed. ing.
The structure will be described in detail. A base plate 7 is provided on the main body frame 6, and the base plate 7 can be moved in the left-right direction in FIG. 1 by a motor 9 fixed by a holder 8. On the base plate 7, the perforating means 4 is provided via the mounting member 10 and the X-ray camera 5 is provided via the mounting member 11. Mounting member 1
A motor 13 is attached to the holder 0 via a holder 12, and the attachment member 10 and the drilling means 4 are movable in the front-back direction in FIG. 1 by the operation of the motor 13. The motors 9 and 13, the base plate 7, the mounting member 10 and the like are collectively referred to as an XY table mechanism 3. The drilling means 4 includes a motor 4a, a chuck 4b, and a drill 4c.
It consists of and. Above the table 2, there is a hole 2
An X-ray irradiation means 14 is arranged so as to face the X-ray camera 5 or the perforating member 4 via a.

FIG. 2 shows a block diagram of a control circuit of the punching device having such a configuration. The central processing unit (hereinafter referred to as “CPU”) 15 includes an X-ray irradiation unit 14,
An image input device 16 to which an image is input from an X-ray camera 5 which receives an X-ray image by the X-ray irradiation means 14, and an image storage device 17 which can store the image from the image input device 16.
A display device 18 such as a display for displaying this image is connected. The CPU 15 and the image input device 1
6, the image storage device 17 and the like are shown as image processing means. Further, the CPU 15 includes a read only memory (hereinafter referred to as “ROM”) 19 in which an image processing program is stored, and a random access memory (in which a positioning program corresponding to an identification mark position is stored). Hereinafter referred to as "RAM".) 20
And the XY table mechanism 3 and the perforating means 4 described above are connected.

Next, a method of drilling a substrate using this apparatus will be described. According to the method of the present invention, the X-ray irradiation dose is first determined before the actual punching of the printed circuit board. FIG. 3 shows a flowchart of this operation.

When the printed circuit board 1 is supplied onto the table 2, C is printed based on the image processing program stored in the ROM 19.
A command is sent from the PU 15 to the X-ray irradiation means 14, and the X-ray irradiation means 14 performs the first X-ray irradiation toward the identification mark (not shown) on the printed circuit board 1 (step A). The X-ray irradiation means 14 used in this embodiment is
It is set so that a predetermined amount of X-ray is emitted for each operation.

Then, the X-ray transmission image of the printed circuit board 1 becomes X.
Reach the line camera 5. Therefore, based on a command from the CPU 15, the image captured by the X-ray camera 5 is changed to the image input device
In step 6, the pixel position is A / D converted for each pixel, the result of the first irradiation is stored in the image storage device 17 (step B), and the center position of the identification pattern is calculated (step C). As this center position calculation method, various known methods can be adopted. For example, two intersections of the X axis set in the imaging area and the pattern outer periphery are obtained, and the average value of the X coordinates is calculated as the center point. A so-called four-point search method or the like is adopted in which the X coordinate is used, and similarly, the average value of the Y coordinates of two intersections of the Y axis and the pattern outer periphery is used as the Y coordinate of the center point. In this way, as the result of the first irradiation, the X-ray transmission image and the center point coordinates are stored. For example, in this embodiment, the X coordinate of the center point calculated here is defined as P ₁ with the X coordinate as a reference. At this point in time, since a sufficient amount of X-rays for pattern position detection are not supplied,
The X-ray transmission image has a lot of noise and a large error in the coordinates of the center point.

Next, based on a command from the CPU 15, a second X-ray irradiation is performed by the X-ray irradiation means 14 (step A).
′), X through the X-ray camera 5 and the image input device 16
A line transmission image is obtained. This transmission image is added to the image at the time of the previous X-ray irradiation (steps A to B) stored in the image storage device 17 (step B ′), and the added image is stored in the image storage device 17. At the same time, the center position of the identification mark is calculated from the added image (step C '). As a result, the image of the identification pattern becomes clearer than that of the previous time and an image with reduced noise is obtained, and the center position can be detected more accurately than the previous time. In addition,
The X coordinate of the center point calculated at this time is P2. Therefore, the average value of the calculated value P ₂ and _{P 1 P'2 = (P 2} +
P ₁ ) / 2 is calculated (step D).

Then, based on a command from the CPU 15, the X-ray irradiation means 14 performs the third X-ray irradiation, and an X-ray transmission image is obtained via the X-ray camera 5 and the image input device 16 (step A). ″). This transmission image is compared with the first image processing result stored in step E and 2
It is further added to the image obtained by adding the result of the image processing of the second time (step B ″). Then, the added image is stored in the image storage device 17 and the center position of the identification mark is calculated (step C ″). ). Then, the X coordinate of the center point calculated at this time is defined as P ₃ . Therefore, the average value P ′ ₃ = (P ₁ + P ₂ + P ₃ ) / 3 with the calculated value P ₃ is calculated. Furthermore, the variation of these average values ΔP ′ ₃ = | P
′ ₂ −P ′ ₃ | is obtained (step D ′).

When the X-ray irradiation is repeated in this manner, the detected coordinates of the center point become gradually more accurate. Therefore, FIG.
As shown in, the variation of the detection result gradually decreases and converges toward the actual center point P _X (which is unknown at the time of performing the work). Here, in the case where the center position is detected with an accuracy of ± Q in consideration of the tolerance of the center position detection, the work is continued until the variation is within the width of the tolerance range. That is, here ΔP
′ ₃ and Q are compared, and if ΔP ′ ₃ > Q, the work is continued (step E).

Such an X-ray irradiation process (step A ″)
Repeating the above, each time, the obtained image is added to the added image up to the previous time (step B ″), and the center position of the identification mark is obtained from this added image (step C ″). Each time X-ray irradiation is repeated, the image becomes clear, noise is reduced, and the accuracy of the center position is improved. Therefore, the amount of change becomes smaller as the number of times increases. Specifically, n
When X-ray irradiation is performed once, first, the average value P ′ _n = (P
_{1 + P 2 + P 3 +} ··· + P (n-1) + seek P _n) ÷ n, Furthermore, variation _{ΔP' n = | P'(n-} 1) -P' n | asking (step D' ), Comparing the magnitudes of ΔP ′ _n and Q (step E), and when ΔP ′ _n <Q, set the required number of irradiations to n (step F) and set the X-ray irradiation dose. Complete the work to make a decision.

After the required number of X-ray irradiations (n times) is determined as described above, the actual drilling operation is started.
The flowchart is shown in FIG.

When the printed circuit board 1 to be processed is supplied onto the table 2, an identification mark (not shown) is formed on the hole 2a.
The printed board 1 is fixed by a gripping means (not shown) so as to face (step G). Therefore, the X-ray irradiator 14 irradiates the printed circuit board 1 n times with X-rays (step H). An X-ray camera 5 captures a transmission image of the printed circuit board 1 that has received this irradiation. Then, the captured image is captured from the image input device 16 and stored in the image storage device 17. Then, according to the image processing program stored in the ROM 19, the X-ray transmission image is image-processed to obtain the center point of the identification mark (step I). The coordinates of the center point are temporarily stored in the RAM 20. In addition,
Unlike the above-mentioned work for setting the required irradiation times, the center point is not detected by image processing for each X-ray irradiation, but the center point is detected only when n times of X-ray irradiation is completed. To do.

When the center point of the identification mark is obtained in this way, the XY table mechanism 3 is driven according to the positioning program stored in the ROM 19 and the punching member 4 is placed at the center point of the identification mark stored in the RAM 20. It is moved (step J), and the printed board 1 is drilled by the drill 4c through the hole 2a (step K). Although not shown in the flowchart, the stored image is displayed on the display device 18 in parallel with steps I to K.

In the above embodiment, until the variation of the image processing result (the position of the identification mark center point) falls within the allowable range,
Although X-ray irradiation and image processing were actually performed n times, it is also possible to estimate the required number of irradiations by looking at the convergence of the image processing results. The method will be described below with reference to the flowchart of FIG.

Similar to the above-described example, first, X-ray irradiation is performed (step A "), images are added each time (step B"), and the center point of the identification mark is obtained by image processing (step C "). Then, the average value P ′ _i and the variation ΔP
′ _I is calculated (step D ′). Then this ΔP
′ _I and the amount of change ΔP obtained during the (i−1) th X-ray irradiation
' _(I-1) and the convergence speed V _i = | ΔP' _(i-1) −ΔP
′ _I | is obtained (step L). At this time, since it is premised that the variation is converged every time the X-ray irradiation is repeated, the change amount ΔP ′ _i and the reference value R _P are compared (step M), and ΔP ′ _i is the reference value R. If it is larger than _P and the variation is divergent, increase the initial value of the number of X-ray irradiation and then perform again.

As shown in FIG. 4, the image processing result gradually converges, but the convergence speed Vi (corresponding to the slope of the graph in FIG. 4) gradually becomes smaller and the fluctuation range becomes smaller. When the convergence speed V _i becomes small to some extent, it is considered that the variation becomes almost constant. That is, when the convergence speed V _i becomes smaller than the preset reference value R _V , it can be considered that the convergence speed V _i hardly changes thereafter. Therefore, the convergence speed V _i is compared with R _V (step N), the X-ray irradiation is completed when V _i <R _V, and the necessary irradiation number is estimated. Specifically, it is calculated how many times the remaining X-ray irradiation is performed under this convergence speed V _{i so} that the variation ΔP ′ _i falls within the allowable range Q (step O). That is, (ΔP ′ _i −Q) ÷ V
_{If i} = j, then it can be seen that if the X-ray irradiation is performed j times thereafter, the variation in the image processing result falls within the allowable range. That is, it can be estimated that the required number of irradiations at this time is m = i + j. According to this method, the required number of irradiations can be obtained even if the work is not actually performed m times but only i times less than that.

In the above embodiments, the X-ray irradiating means for irradiating a predetermined amount of X-rays in one operation is used, and the X-ray irradiating means is operated a plurality of times. However, as another embodiment,
The X-ray may be continuously and continuously irradiated, and the image input device may be configured to periodically capture an image at predetermined time intervals. In that case, in the work for initial setting, the number of times of image capture when the image processing result falls within the allowable range is obtained, and based on this, the required irradiation amount of X-rays and the required irradiation time are obtained. Then, in actual processing such as drilling, the X-ray irradiating means is operated for the set required irradiation time.

Further, although the X coordinate of the center point of the identification mark is used as a reference for observing the degree of variation in the image processing result, the present invention is not limited to this, and it is guided by image processing. Any data can be used.

In the above description, an example in which the invention is applied to a device for punching a printed circuit board is shown, but the present invention is not limited to this and is applied to all imaging devices using X-rays. It is a thing.

[0028]

According to the X-ray imaging method of the present invention, it is possible to easily calculate the minimum X-ray irradiation dose necessary for maintaining the image processing accuracy without the user's visual observation, and the work efficiency is improved. It is possible to improve and contribute to cost reduction, and it becomes possible to automatically set X-ray irradiation conditions.

[Brief description of drawings]

FIG. 1 is a front view of a main part of a substrate punching device using an embodiment of the present invention.

FIG. 2 is a block diagram of the substrate punching device shown in FIG.

FIG. 3 is a flowchart showing a necessary irradiation amount setting operation of the X-ray imaging method according to the present invention.

FIG. 4 is an explanatory diagram showing variations in image processing results.

FIG. 5 is a flowchart showing a board hole drilling operation following the required irradiation amount setting operation shown in FIG.

FIG. 6 is a flowchart showing another embodiment of the necessary irradiation amount setting work of the X-ray imaging method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printed circuit board (work) 5 X-ray camera (imaging means) 14 X-ray irradiation means 15 Central processing unit (CPU) 16 Image input device 17 Image storage device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H05K 3/46 X 6921-4E

Claims (4)

[Claims] 1. An X-ray irradiating means for irradiating an X-ray, and the above X
X-rays by the X-ray irradiating means, using image pickup means for picking up a transmission image of X-rays radiated on the work from the ray irradiating means and image processing means for performing image processing based on the image pickup result by the image pickup means. Irradiation is performed on a specific work, and the transmitted image is image-processed each time the X-ray irradiation amount increases by a predetermined amount, and compared with the image processing results up to the previous time, the dispersion of the image processing results converges within a predetermined range. X at the time
It is characterized in that the radiation dose is set as the required radiation dose, and when the work is imaged thereafter, X-ray radiation of the required radiation dose is performed and the image processing is performed based on that. X-ray imaging method. 2. The X-ray irradiating means irradiates a predetermined amount of X-rays by one operation, and the X-ray irradiating by the X-ray irradiating means is repeatedly performed on a specific work and is obtained each time. The transmitted images are sequentially added, the image processing is performed on the added image, and compared with the image processing result based on the added image up to the previous time, when the variation of the image processing result converges within the predetermined range. The number of times of X-ray irradiation is set as a necessary number of times of irradiation, and when the work is imaged thereafter, the above-mentioned number of times of irradiation of X-rays is performed and image processing is performed based on the number of times of irradiation. X according to claim 1.
Line imaging method. 3. A difference between a calculated value obtained from n (n is a natural number) X-ray irradiation addition images and a calculated value obtained from (n-1) X-ray irradiation addition images, and the difference is calculated. 3. When the absolute value of X falls within a predetermined range, the n is set as the required number of irradiations, X according to claim 1 or 2.
Line imaging method. 4. The work is a substrate on which a pattern is formed in advance, the position of the pattern of the work is detected by using the X-ray imaging method according to claim 1, and the pattern is formed. A substrate processing method, wherein the substrate is processed based on a position detection result.