JP2750450B2 - Standard drilling method for multilayer laminates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to an inner metal layer in a printed wiring board, particularly in a multilayer laminate in which conductors and insulators are alternately formed in a plurality of layers. And a drilling method for providing a reference hole at a reference hole position mark.

(Prior Art) In recent years, with the demand for miniaturization and high performance of electronic devices, multilayer laminates having one or more conductive metal circuits inside have been frequently used as wiring boards on which electronic components are mounted. .

In such a multilayer laminate, it is necessary to match the positional relationship between the circuits of the inner metal layers and the circuit of the outer metal layer to be formed after lamination. That is being done.

That is, a mark (reference hole position mark) serving as a reference point is provided in advance on the inner metal layer of the multilayer laminate, and a reference hole is made at this point to be used for positioning during outer layer processing. However, since the reference hole position mark in the inner metal layer is not visible from the outside, it is difficult to directly and accurately drill the hole, and the hole is drilled by the following method.

(A) Counterbore method The case of a six-layer laminate shown in FIG. 5 will be described as an example.

In FIG. 5, first, the end mill cutter 3 performs counterbore around the reference hole position mark 2 of the outer first metal layer 1a until the mark itself on the second metal layer 1b is exposed. Thereafter, a centering machine is used by using a boring machine with a magnifying glass using reflected light, or image processing is performed on the reference hole position mark, and the center of gravity is formed.

Further, only the metal layers of the first metal layer 1a and the sixth metal layer 1f are spotted by the end mill cutter 3 to transmit light from above or below, and the reference hole position mark 2 which can be seen through.
Is centered by a drilling machine with a magnifying glass or image processing to perform drilling.

In this case, if the metal layer other than the second metal layer 1b includes the reference hole position mark 2 or a metal layer that blocks light, the method cannot be applied.

(B) Direct drilling method This is a method in which a reference hole position mark formed on the inner second metal layer 1b shown in FIG.

(Problems to be Solved by the Invention) Both the methods (a) and (b) have the following common disadvantages.

(1) Normally, since a reference hole is formed based on the reference hole position mark of one of the second metal layer 1b and the inner metal layer, the hole is formed by ignoring a deviation from the other inner metal layers. .

(2) Therefore, it is not possible to determine whether or not the interlayer displacement between the inner layers is within a specified value.

Due to such a problem, in the case of a multilayer board, especially a multilayer board having six or more layers, a large gap may occur between the inner layers even if the holes in the marks of the second metal layer 1b seem to be accurate. Since the circuit is defective, the yield of the multilayer laminate deteriorates.

In order to prevent this, it is necessary to measure the amount of interlayer misalignment based on the second metal layer mark for each layer and send it to the next process, which significantly increases the number of inspection steps and lowers production efficiency.

The present invention is intended to solve such a problem.

[Constitution of the Invention] (Means for Solving the Problems) In the reference drilling method for a multilayer laminate according to the present invention, the reference hole position mark provided on the inner substrate metal layer has two or more inner substrate metal layers. At the same time, the upper reference hole position mark is soft X
Perspective by a line, the obtained still image is subjected to image processing to obtain the area of the figure surrounded by the outer circumference of the mark where the reference hole position mark overlaps, or the area of the figure surrounded by the inner circumference of the overlapped mark. The method is characterized in that a center of gravity is obtained and a hole is formed at the position of the center of gravity.

(Operation) In the reference hole forming method of the multilayer laminate of the present invention, the reference hole position marks on the two or more inner-layer substrate metal layers are simultaneously viewed through soft X-rays, and the obtained still image is subjected to image processing. By calculating the area of the figure surrounded by the outer periphery of the mark where the reference hole position mark overlaps, or the center of gravity of the area of the figure surrounded by the inner periphery of the overlapped mark,
Since the hole is drilled at the position of the center of gravity, the amount of displacement between the inner metal layers is minimized.In the obtained multilayer laminate, a plurality of reference hole intervals include the maximum amount of displacement between the layers of the multilayer laminate. By measuring the hole interval, the amount of misalignment between layers can be determined, and the pass / fail judgment can be made quickly.

(Example) Hereinafter, a reference hole making method for a multilayer laminate according to the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory view of an apparatus of the present embodiment to which the method of the present invention is applied, FIG. 2 is a perspective view showing the relationship between reference holes provided in the multilayer laminate of FIG. 1, FIG. FIG. 4 is an explanatory diagram relating to a method of obtaining the center of gravity for the reference hole position mark according to the present invention.

The reference hole position mark drilling device is installed in the X-ray shielding cover 11, and the soft X-ray irradiation unit 12, drill unit 1
3, a support arm 14 to which these are fixed, an XY table 15 on which the multilayer substrate 1 to be processed is placed and moved, a soft X-ray image receiving device 16, and signal processing for the output of the soft X-ray image receiving device 16. And a control device 18 that generates a control signal based on the processing result.

As shown in FIG. 2, a multilayer laminated board 1 (first
The metal layer 1a), the reference hole position mark 2a of the inner layer,
Reference holes 6, 7, 8 based on 2b, 2c, 2d are provided.

Regarding the positional relationship of the multilayer laminate and the reference hole position mark of each layer, the same symbols are used for the same parts as those in FIG. 3 described above.

In FIG. 1, the soft X-ray irradiation unit 12 is moved,
Each reference hole position mark 2a, 2 of the inner metal layer of the multilayer laminate 1
b, 2c, and 2d are irradiated with soft X-rays, and the soft X-ray image receiving device 16 obtains perspective images thereof. The image signal of the perspective image is obtained by the image processing device 17
Is processed by

As shown in FIGS. 3 and 4, the processing procedure is as follows: (1) The reference hole position mark may be a hole having a fixed outer periphery or a hole having a fixed inner periphery. since the soft X-ray that has passed through the reference hole position mark of the mark outer periphery or inner circumference overlapping shapes a, or a ₂ is obtained, obtaining the center of gravity by calculation process for this. The positions a ₁₀ and a ₂₀ are set as drilling centers.

(2) centered on the center of gravity obtained by the, in the case of Figure 3 obtains the maximum radius R ₁ of a circle circumscribing the mark periphery, of the original diameter d ₀ of the diameter and the reference hole position marks of the circle It is determined whether or not the difference is within a specified deviation amount (g ₀ ).

2R ₁ -d ₀ <g ₀ ... (1) In the case of FIG. 4, the minimum radius R2 of the interior centered on the obtained center of gravity is determined, and from this diameter, the original diameter d ₀ of the reference hole position mark is calculated. It is determined whether or not the difference is within a specified deviation amount.

2R ₂ dd ₀ <g ₀ (2) When the above (1) or (2) is satisfied, it is determined that the product is good. The reference unit is drilled by the drill unit 13 by moving it by 11.

The case where one reference hole 6 is drilled has been described above, but reference holes are provided for the other reference holes 7 and 8 in the same procedure.

In this manner, the reference holes 6, 7, 8 formed with the minimum deviation amount relationship with respect to the reference hole position marks between the respective layers.
By measuring the distance between the XY tables 15 and the distance between them, it is possible to compare the measured values with the specified values of the respective reference drilling pitches, and determine the quality of the laminated substrate alone.

[Effects of the Invention] According to the present invention, it is possible to perform reference drilling in a positional relationship in which the amount of displacement between layers is averaged using reference hole position marks of a predetermined size. The yield can be improved, and the quality of the multilayer laminate can be quickly determined by measuring the interval between the reference holes, so that defective products can be removed in advance.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an apparatus of the present embodiment to which the method of the present invention is applied, FIG. 2 is a perspective view showing the relationship between reference holes provided in the multilayer laminate of FIG. 1, FIG. FIG. 4 is an explanatory diagram relating to a method of obtaining a center of gravity for a reference hole position mark according to the present invention, and FIG. 5 is an explanatory diagram illustrating a method of providing a reference hole for a reference hole position mark of a conventional multilayer laminate 1. . DESCRIPTION OF SYMBOLS 1 ... Multilayer laminated board 1b, 1c, 1d, 1e ... Inner-layer board metal layer 2a, 2b, 2c, 2d ... Reference hole position mark 10 ... Reference hole position mark drilling device 12 ... Soft X-ray irradiation unit 13 ...... Drill unit 15 XY table 16 Soft X-ray image receiving device 17 Image processing device 18 Control device

Claims (1)

(57) [Claims] 1. A reference image of a reference hole position mark provided on an inner substrate metal layer, wherein the reference hole position marks on two or more inner substrate metal layers are simultaneously viewed through soft X-rays to obtain a still image. On the other hand, by performing image processing, the center of the area of the figure surrounded by the outer periphery of the mark where the reference hole position mark overlaps or the center of gravity of the area of the figure surrounded by the inner periphery of the overlapped mark is determined, and the hole is formed at the position of the center of gravity. Reference drilling method characterized by the following.