JPS6325884B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a hole drilling position detection method for detecting the drilling position of a hole drilled on an inner layer circuit of a multilayer printed wiring board.

[Background technology]

Multilayer printed wiring boards used in electronic devices and the like are generally manufactured as follows. First, metal foil is attached to both or one side of the inner layer prepreg, and an inner layer circuit is formed on this to create an inner layer circuit board. With respect to one inner layer circuit board or a plurality of inner layer circuit boards arranged in a plane, outer layer prepregs are stacked on top and bottom, metal foil is further stacked on the outside of these, and heat and pressure molding is performed.
After that, if a plurality of inner layer circuit boards are arranged side by side, rough cutting is performed for each inner layer circuit. For the intermediate product of the multilayer printed wiring board produced after the molding, the hole mark indicating the position of the reference hole, which is displayed on the surface of the inner layer circuit board, is detected from the outermost layer metal foil side. A spot with a hole mark is counterbored from above to expose the hole mark. Drill a reference hole in the center of this hole mark. Then, by forming an outer layer circuit on the outermost layer of metal foil using this reference hole as a reference, a multilayer printed wiring board is completed.

However, the above manufacturing method has the following problems. This is because in intermediate products of multilayer printed wiring boards, which consist of multiple inner layer circuit boards arranged side by side, the inner layer circuit boards are hidden from view due to the outermost layer of metal foil, making it difficult to determine the rough cutting position. When searching for dots and hole marks, the hole marks are blocked by the outermost layer of metal foil and cannot be seen, so the exact position cannot be determined.Also, there is a problem of misalignment between the outer layer and the inner layer circuit board during hot press molding. The problem is that the exact position of the hole mark is becoming increasingly difficult to determine.

Therefore, in order to solve the above problems, the following hole mark detection method was developed. As shown in FIG. 1, after forming the inner layer circuit 1a and the hole mark 1b on the inner layer prepreg 2, the outer layer prepreg is attached with a patch (guide mark) 3 pasted on the hole mark 1b in advance. 4,
4 and metal foils 5, 5 are stacked and heated and press-molded. Finished multilayer printed wiring board intermediate product 6
However, it is visually determined that the patch 3 bulges by the thickness of the patch 3 and that the portion 5a on the metal foil 5 shines slightly. Then, counterbore the determined position and peel off the patch to expose the hole mark. Since the upper surface of the exposed hole mark is contaminated with resin or the like, it can be clearly exposed by polishing the upper surface. Then, the hole mark is visually observed with a magnifying glass and the center position of the hole mark is determined. In the figure, 1 is an inner layer circuit board. However, the above method
There were problems such as the need for additional patching and polishing processes, the need to visually detect the position of the hole mark, which was extremely tiring on the eyes, and errors in the detection position. In addition to the above method, a method has been developed for detecting hole marks formed on the inner layer circuit board from the surface of the outer layer metal foil using various sensors. However, since detection was performed from the surface of the outer metal foil, there was a problem in that errors inevitably occurred in the detection position.

[Purpose of the invention]

An object of the present invention is to solve the above-mentioned problems and provide a method for detecting the position of holes in a multilayer printed wiring board with extremely high detection accuracy.

[Disclosure of the invention]

In order to achieve the above object, the inventors conducted extensive studies and completed this invention.

This invention detects the position of a hole by detecting the position of the hole mark of a multilayer printed wiring board in which hole marks indicating the position of the hole are formed at an appropriate number of locations on the inner layer circuit board. This is a method for detecting the position of holes in a multilayer printed wiring board, in which counterbore processing is performed from both the front and back sides of the position predicted to be the hole mark position in the multilayer printed wiring board, and the position of the hole mark is determined by a light transmission image of the hole mark. The gist of this paper is a method for detecting the position of holes in a multilayer printed wiring board, which is characterized by detecting the position of holes in a multilayer printed wiring board.
Hereinafter, this will be explained in detail based on drawings showing examples thereof.

As shown in FIG. 2, in the method for detecting hole drilling positions in a multilayer printed wiring board according to the present invention, hole marks 1b indicating hole drilling positions are formed at several locations on an inner layer circuit board 1, as in the conventional method. In this method, the position of the hole is detected by detecting the position of the hole mark 1b in the multilayer printed wiring board 7. The hole mark 1b indicates the position of a reference hole that will be a reference when forming a circuit in the outer layer metal foil 5 to correspond to the inner layer circuit 1a. First, a counterboring process is performed using a counterboring means from both the front and back sides of the position where the hole mark 1b is predicted to be located in the multilayer printed wiring board 7. The method for predicting the hole mark position is as follows:
It varies. For example, as shown in FIGS. 5 and 6, three peripheral edges of the circuit pattern 1a having the hole marks 1b of the inner layer circuit board 1 are preliminarily marked.
Metal marks 8a, 8b, and 8c, which serve as references for determining the coordinates of the hole mark 1b, are formed simultaneously with the circuit pattern 1a. These metal marks 8
As shown in Fig. 7, a, 8b, and 8c are for determining the x and y coordinates of the inner layer circuit board. The x-axis is a straight line that intersects at right angles and passes through the center point of the mark 8c. The coordinate position of each hole mark 1b is determined in accordance with these xy coordinate axes. As shown in FIG. 6, the metal marks 8a, 8b, and 8c are placed in the inner direction (in the direction of the arrow) while leaving a certain distance from the edge of the surface of the outer layer metal foil 5 to the surface of the metal foil 5. The position is measured by scanning the eddy current sensor 9 (also shown in FIG. 5). As a result, the position of the hole mark 1b is determined. An eddy current sensor generates a high-frequency magnetic field and detects a conductor by utilizing the fact that the impedance of the sensor coil changes due to eddy current loss generated in the conductor due to the magnetic field. In this embodiment, since the eddy current loss due to the outer layer metal foil is constant, the change in eddy current loss when the outer layer metal foil and the metal mark overlap is detected. In this case, a magnetic sensor may be used instead of the eddy current sensor.
Marks 8a, 8b, 8c that serve as references for the xy coordinate axes
By using a mark consisting of a bar scale with information about the xy coordinate system, only one mark is required. On the other hand, as disclosed in U.S. Pat.
There are also mechanical methods of predicting hole mark positions by non-penetrations. In this embodiment, a multilayer printed wiring board is mounted on an XY table (not shown) that operates based on an XY coordinate system. The multilayer printed wiring board is moved to the counterbore location using this XY table. As shown in FIG. 2, end mills (bottom milling cutters) 12a and 12b, which serve as counterboring means, are provided on both upper and lower sides of the pedestal 11, respectively.
A hole 11a is formed in the pedestal 11 to receive the lower end mill 12b. First, the upper end mill 12a is lowered from above to form the counterbore hole 12c. At this time, the counterbore depth A is controlled using the downward displacement of the end mill after the contact signal between the metal foil 5 and the end mill 12a is output by the continuity detector, or the progress of the fall. Next, the lower end mill 12b is raised at the same position to form the counterbore hole 12c, and although not shown, the counterbore depth B is controlled in the same manner as the upper end mill 12a. At this time, the distance C between the bottom surface of the upper counterbore hole 12c and the hole mark 1b is desirably about 0.1 to 0.3 mm, and the counterbore depth B of the lower counterbore hole 12c is desirably about 0.1 mm. The reason why the interval C is set in this way is because normally, if it is smaller than 0.1 mm, there is a risk of spot facing the hole mark 1b, and if it is larger than 0.3 mm, it will be difficult to obtain a light transmitted image of the hole mark 1b. It is. The interval B is also set for substantially the same reason. However, the numerical value regarding the counterbore depth is not limited to the above numerical value. In the figure, 13
is an airtight chamber, and 13a is an end mill 12 with a counterbore.
13b is a dust collection path for collecting chips and the like in the airtight chamber 13; 14 is a rubber material for improving the airtightness of the airtight chamber 13; 15 is an air blower for blowing off chips attached to the surface; 15a is a contact pin (contactor) for contacting the metal foil 5 and connecting it to the continuity detector; 15a is the contact pin 15;
16 and 16a are springs that urge the contact pin 15 and the pin 15a downward, 17 is a brush for connecting the rotor 18 connected to the end mill 12a and the continuity detector, and 17a is a pin having the same shape as . The brush holder 19 is a timing belt for rotating the end mill 12a. When the counterbore processing from both the front and back sides of the multilayer printed wiring board is completed, the counterbore portion of the multilayer printed wiring board is moved to below an ITV camera (industrial television camera) using an XY table. As shown in FIG. 3, illumination is applied to the counterbore hole 12c from below by optical fibers 20, 20, and as shown in FIG. 4, a light transmission image of the hole mark 1b is captured by the ITV camera 21. If this light transmission image is image-processed, the center point 26 of the hole mark 1b can be derived, so that the drilling position of the reference hole can be detected with high precision without error. Moreover, since the detection is not performed visually, the eyes will not get tired. It is also suitable for automation. Furthermore, the multilayer printed wiring board 7 is moved based on an XY table (not shown),
If the center point of the hole mark 1b is placed directly above the central axis of the drill 22, the reference hole can be drilled with high precision. In this case, drill 2
Another method is to attach the rotary drive unit 2 to another fine-movement XY table (not shown) and move the fine-movement XY table to align the center axis of the drill 22 with the center point of the hole mark 1b. In FIG. 3, 11 is a pedestal, 23 is a holding member for creating an airtight state on the surface of the multilayer printed wiring board 7 and holding down the wiring board 7, and 23a is for blowing away chips after drilling the hole with the drill 22. 23b is a transparent glass, 25 is a chip collection path, 12c is a counterbore in FIG. 4, and 27 is the field of view of the ITV camera.

In the embodiment, the hole marks detected by the hole drilling position detection method for a multilayer printed wiring board according to the present invention are as follows:
It indicated the position of the reference hole for forming the outer layer circuit. However, the present invention is not limited to this, and for example, it may indicate a hole for through-hole plating. Further, there is no particular limit to the number of hole marks formed.

In the example, when capturing a light transmission image of a hole mark, the illumination is applied from below and the light is applied from above.
It was captured by an ITV camera. However, the positions of the illumination and ITV camera are not limited to those in the example. Furthermore, the device that captures light transmission images is not limited to ITV cameras;
Other image pickup tubes may also be used.

〔Effect of the invention〕

As described above, the method for detecting the hole drilling position of a multilayer printed wiring board according to the present invention is applicable to a multilayer printed wiring board in which hole marks indicating the hole drilling positions are formed at an appropriate number of locations on the inner layer circuit board. A hole drilling position detection method for a multilayer printed wiring board that detects a hole drilling position by detecting the position of the hole mark, the method comprising: detecting a hole drilling position on both sides of the predicted hole mark position in the multilayer printed wiring board; Since the method is characterized in that a blank counterboring process is performed and the position of the hole mark is detected by a light transmission image of the hole mark, the effect that the hole drilling position can be detected with extremely high accuracy is brought about.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view illustrating a conventional method for detecting the position of holes drilled in a multilayer printed wiring board, and FIGS. 4 is an enlarged plan view showing a counterbore hole, and FIGS. 5 to 7 are explanatory views for explaining a method for predicting the hole mark position, Fifth
FIG. 6 is a plan view of the inner layer circuit board, FIG. 6 is an explanatory diagram of the mark detection process, and FIG. 7 is an explanatory diagram illustrating a coordinate conversion method for replacing the hole mark position on the outer layer metal foil. DESCRIPTION OF SYMBOLS 1... Inner layer circuit board, 1a... Inner layer circuit, 1b... Hole mark, 5... Outer layer metal foil, 7... Multilayer printed wiring board, 1
2c...Spothole, 15...Contact pin (contactor), 20...Optical fiber, 21...ITV camera.

Claims (1)

[Scope of Claims] 1. Hole drilling is performed by detecting the positions of hole marks of a multilayer printed wiring board in which hole marks indicating hole drilling positions are formed at appropriate locations on an inner layer circuit board. This is a method for detecting the position of holes in a multilayer printed wiring board, in which counterbore processing is performed from both the front and back sides of the position predicted to be the hole mark position in the multilayer printed wiring board, and the hole is detected using a light transmission image of the hole mark. A method for detecting the position of holes in a multilayer printed wiring board, which is characterized by detecting the position of a mark. 2. A patent claim in which the depth of the counterbore is controlled by the counterbore means receiving a continuity detection signal due to the contact between the contact and the outer layer metal foil as the counterbore means moves, by controlling the amount of push-in of the counterbore means. range 1
A method for detecting the position of holes in a multilayer printed wiring board as described in 2.