JP2762130B2 - 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 method of forming 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 laminated board, 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, so that the inner layer reference hole position mark is formed. 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 plate shown in FIG. 5 will be described as an example.

First, using the reference hole position mark 21a of the outer first metal layer 20a, the vicinity of the reference hole position mark 21b of the second metal layer 20b is moved to the second position.
The spot milling is performed by the end mill cutter 30 until the mark 21b on the metal layer 20b itself is exposed. Then, using a drilling machine with a magnifying glass using reflected light, or image processing of a reference hole position mark by a CCD camera, centripetal processing is performed, and the center of gravity is punched.

Only the metal layers of the first metal layer 20a and the sixth metal layer 20f are spotted by the end mill cutter 30 to transmit light from above or below, and the reference hole position marks 21b and 21e 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 20b has the reference hole position marks 21b and 21e or the 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 20b shown in FIG. 5 is directly image-processed by a soft X-ray camera to perform centering and drilling.

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

1) Normally, a reference hole is formed with reference to a reference hole position mark of one of the second metal layer 20b and the inner metal layer.
The hole is drilled ignoring the deviation from the other inner metal layers.

2) Therefore, it cannot be determined whether or not the amount of interlayer displacement between the inner layers is within a specified value.

Due to such a problem, in the case of a multilayer board, particularly a multilayer board having six or more layers, it is apparent that a large gap occurs between the inner layers even if the mark is drilled accurately at first glance. In addition, 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) According to the reference drilling method for a multilayer laminate of the present invention, a reference hole position mark is provided on an inner substrate metal layer, and an interlayer misalignment mark is provided at a peripheral portion of the inner substrate metal layer. Provided, a certain layer as a reference layer, a reference hole position mark of this reference layer as an origin mark, the origin mark, an interlayer misalignment mark of the reference layer, and an interlayer misalignment mark on each inner layer metal layer other than the reference layer. about,
The center of gravity of the origin mark, the center of gravity of the area of the outer periphery of the mark of each interlayer displacement mark, or the center of gravity of the area of the inner circumference of the mark is obtained by performing image processing on a still image obtained through fluoroscopic X-rays. The amount of displacement between layers and the distance between the origin mark and the interlayer displacement mark are measured, the displacement position with respect to the center of gravity of the origin mark is calculated based on the displacement amount, the center of perforation is set, and the hole is drilled with respect to the center of perforation. And

(Operation) In the reference hole drilling method of the multilayer laminate of the present invention, a reference hole position mark is provided on the inner substrate metal layer, and an interlayer misalignment mark is provided on the peripheral portion of the inner substrate metal layer, and one layer is used as a reference layer, The reference hole position mark of the reference layer is used as an origin mark, and the origin mark, the interlayer misalignment mark of the reference layer, and the interlayer misalignment mark on each of the inner-layer substrate metal layers other than the reference layer are obtained by simultaneously seeing through soft X-rays. By performing image processing on the obtained still image, the center of gravity of the origin mark, the center of gravity of the area of the outer periphery of each of the interlayer misalignment marks, or the center of gravity of the area of the inner periphery of the mark is obtained, and the amount of misalignment between the layers is measured. If the result does not fall within the specified value, remove it as a defective product, measure the distance between the origin mark and interlayer misalignment mark for a good product, calculate the misalignment position with respect to the origin mark center of gravity based on the amount of misalignment, and drill A center is set and a hole is drilled with respect to the center of the perforation. The drilled multilayer board has the origin mark center of gravity as the virtual center, and the reference holes are provided at positions where the amount of deviation between the layers is evenly distributed, and the drilling pitch between the reference holes is measured. Since it is possible, a high-quality multilayer laminate having a high precision of the drilling pitch between the reference holes can be obtained.

(Example) Hereinafter, a reference drilling 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. FIGS. 4A and 4B are explanatory diagrams showing the relationship between the interlayer misalignment marks and the method of determining the center of gravity for the interlayer misalignment mark in the present invention.

A reference hole position mark drilling device 1 used in the present invention is installed in an X-ray shielding cover 2 and includes a drill unit 3,
4. Soft X-ray irradiation units 5, 6, supporting arms 7, 8 to which these are fixed, an XY table 9 on which a multilayer laminated substrate 10 to be processed is placed and moved, soft X-ray image receiving devices 11, 12, An image processing device 13 for performing signal processing on the outputs of the soft X-ray image receiving devices 11 and 12; Consists of

As shown in FIG. 2, reference holes 21 and 22 based on reference hole position marks 21b and 22b in the inner layer are provided in the multilayer laminated substrate 10 composed of six layers having the first metal layer 10a as the uppermost layer.

Regarding the positional relationship of the multilayer laminate and the reference hole position mark of each layer, the same symbols are applied to the same portions as those in FIG. 5 described above.

 Hereinafter, the reference drilling method of the present invention will be described.

(1) The reference hole position marks 21b and 22b on the inner metal layer 20b of the six-layered multilayer laminate are formed using the two soft X-ray irradiation units 3 and 4 and the soft X-ray image receiving devices 11 and 12. The reference hole position marks 21b and 22b are scanned to obtain a perspective image, and the center of gravity of each mark image is obtained, and this is set as a reference origin.

(2) The distance between the centers of gravity, that is, the reference hole pitch dimension 1 is measured.

If the measured pitch size is 11, the design pitch size is 10, and the tolerance is α, then 10−α <11 <10 + α It is determined from the above formula whether the pitch size is within the specified value.

(3) Measure the distance between the interlayer displacement marks 24, 25 provided on the outer peripheral portion of the reference origin layer, here the inner metal layer 20b, and the reference origin 21b, and the distance between the interlayer displacement marks 26, 27, and the reference origin 22b, and design values. Is measured.

(4) Interlayer misalignment marks 24b1, 24b2, 24b of reference origin layer 20b
The center of gravity of the interlayer displacement marks 24c, 24d, 24e of 3 and the other layers is measured, and the displacement of each layer with respect to the reference origin layer 20b is measured.

The shape of the interlayer misalignment mark of the reference origin layer is circular, and the interlayer misalignment marks of the other layers use a circle having a larger diameter. From this, as shown in FIG. 3, the amount of displacement between the reference origin layer 20b and the center of gravity of the reference origin layer 20b is obtained by obtaining the center of gravity of the small diameter, the center of gravity of the large diameter, and their coordinates within the same field of view.

(5) After judging that the deviation amount of each inner layer is within the specified value, the design reference hole position mark pitch size is allocated to the virtual center with respect to the measurement reference hole position mark pitch size, and the reference is determined when the hole is drilled. It is assumed that the origin is moved, but it is determined whether or not the change in the measured displacement amount of each layer caused by the movement of the reference origin is within a specified value.

(6) If the above data are good, drill
The units 3 and 4 are moved to make a reference hole.

As described above, according to the present invention, the relative displacement between the inner metal layers can be measured, and the pitch dimension of the reference hole can be measured, whereby the reference hole can be quickly and accurately formed.

Note that the reference hole position mark 23 in FIG.
Drill with design values based on 21 and 22.

[Effects of the Invention] According to the present invention, by providing a predetermined interlayer misalignment mark on each inner metal layer, it becomes possible to measure the absolute misalignment amount with respect to the reference hole position mark as the origin, which significantly reduces the number of inspection steps. The rejection rate as a product also decreased. In addition, since the reference drilling can be performed in a positional relationship in which the amount of displacement between the layers is averaged, the yield as the multilayer laminate is improved, and the interval between the reference holes is measured to quickly form the multilayer laminate. Pass / fail judgment can be made, and drilling can be performed by associating the reference hole pitch with the design dimension. Therefore, quality can be improved by judging pass / fail and averaging the amount of deviation.

[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 the center of gravity for the reference hole position mark according to the present invention. FIG. 5 is an explanatory view showing a method for providing a reference hole for a reference hole position mark of the conventional multilayer laminate 1. DESCRIPTION OF SYMBOLS 1 ... Reference hole position mark drilling device 3, 4 ... Drill unit 5, 6 ... Soft X-ray irradiation unit 9 ... XY table 10 ... Multilayer laminated board 11, 12 ... Soft X-ray image Apparatus 20b ... Inner second metal layer 21, 22, 23 ... Reference hole 21b, 22b ... Reference hole position mark 24,25 ... Interlayer misalignment mark

Claims (1)

(57) [Claims] A reference hole position mark on an inner substrate metal layer;
Providing an interlayer misalignment mark at the periphery of the inner layer metal layer,
One layer is used as a reference layer, and a reference hole position mark of this reference layer is used as an origin mark, and the origin mark, the interlayer misalignment mark of the reference layer, and the interlayer misalignment mark on each of the inner layer metal layers other than the reference layer are softened. The center of gravity of the origin mark, the center of gravity of the area of the mark outer periphery of each of the interlayer misalignment marks, or the center of gravity of the area of the inner circumference of the mark is obtained by performing image processing on a still image obtained through X-ray fluoroscopy. Measuring the distance between the deviation amount and the origin mark / interlayer deviation mark, calculating the deviation position with respect to the origin mark center of gravity based on the deviation amount, setting the center of perforation, and drilling the perforation center. Reference drilling method.