JPS6317564B2 - - Google Patents

Description

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

[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, this is a method of visually determining that the patch 3 is raised by the thickness of the patch 3 and that the portion 5a on the metal foil 5 shines slightly. In the figure, 1 is an inner layer circuit board.
Another method is to detect the position of the hole mark by irradiating the multilayer printed wiring board with X-rays and seeing through the inner layer circuits. However, of the above two methods, the former requires more steps to attach the patch, the position of the hole mark is detected visually, which is very tiring on the eyes, and it is not possible for a machine to distinguish when the raised part of the metal foil shines. Because it is difficult, it is not suitable for automation, and there are problems such as the cost of automation being too high. In addition, the latter method requires safety measures against X-rays, and the investment in X-ray equipment is expensive, making it unprofitable even when automated.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for detecting hole mark positions on a multilayer printed wiring board that solves the above-mentioned problems and can be automated at low cost.

[Disclosure of the invention]

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

The present invention is a hole mark position detection method for detecting the position of hole marks in a multilayer printed wiring board in which hole marks indicating hole drilling positions are formed at a suitable number of locations on an inner layer circuit board. Metal marks that serve as a reference for determining the coordinates of the hole marks are formed at multiple locations on the periphery of the circuit pattern on the inner layer circuit board at the same time as the circuit pattern, and an eddy current sensor is scanned from the edge of the outer layer metal foil surface. A hole mark position detection method for a multilayer printed wiring board, characterized in that the positions of the plurality of metal marks are measured based on changes in the output of the sensor, and the positions of the hole marks are detected based on the measurement results. The law shall be its gist.
Hereinafter, this will be explained in detail based on drawings showing examples thereof.

As shown in FIGS. 2 and 3, the method for detecting the position of hole marks on a multilayer printed wiring board according to the present invention is as follows.
Similar to the conventional method, this method detects the positions of hole marks 1b in a multilayer printed wiring board 7 in which hole marks 1b indicating hole drilling positions are formed at three locations on an inner layer circuit board 1. 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. Note that in FIG. 3, the hole mark is not visible. In advance, metal marks 8a, 8b, 8c, which serve as a reference for determining the coordinates of the hole marks 1b, 1b, 1b, are placed on three peripheral parts of the circuit pattern 1a of the inner layer circuit board 1, which has the hole marks 1b, on the circuit pattern 1a. Form each at the same time. These metal marks 8a, 8b, 8c are for determining the xy coordinate axes of the inner layer circuit board, as shown in FIG.
A straight line passing through the center point of mark 8a and mark 8b is defined as the y-axis, and is perpendicular to the y-axis, and a straight line passing through the center point of mark 8c is defined as the x-axis. The coordinate position of each hole mark 1b is determined in accordance with these xy coordinate axes. As shown in FIG. 3, the metal marks 8a, 8b, and 8c are placed in the inner direction (arrow direction, The position is measured by scanning the eddy current sensor 9 (also shown in FIG. 2). 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. As shown in the graph of FIG. 3, when the eddy current sensor 9 that scans the surface of the outer metal foil 5 comes over the metal marks 8a, 8b, and 8c where the first magnetic field change occurs, the sensor output first changes. A waveform peak point A is formed. Therefore, the positions of the plurality of metal marks 8a, 8b, and 8c are measured based on the output change of the eddy current sensor 9 that forms the first waveform peak point A. Based on this measurement result, the inner layer circuit board 1
The xy coordinate axes defined above are the outer layer metal foil 5.
It rises to the surface. Therefore, the above
The position of each hole mark 1b whose coordinates have been determined in advance according to the xy coordinate axes can also be known on the surface of the outer metal foil 5.

As described above, the method for detecting the position of hole marks on a multilayer printed wiring board according to this embodiment involves forming a metal mark that serves as a reference for the coordinates of the hole marks at the same time as forming the circuit pattern on the inner layer circuit board. The position of the metal mark is measured using an eddy current sensor, and the position of the hole mark is detected based on the measurement result, and the detection is performed using an inexpensive device called an eddy current sensor. Because this process is performed automatically, automation can be achieved at low cost.

Once the position of the hole mark is detected, a reference hole is then drilled at that position to serve as a reference when forming the outer layer circuit. When drilling the reference hole, if the x and y coordinates of the hole mark on the inner layer circuit board are automatically replaced with the corresponding position on the outer layer metal foil through arithmetic processing, etc., the work of drilling the reference hole can also be automated. .

For example, as shown in FIG. 4, the XY coordinate axes are placed on the outline representing the outer shape of the rough-cut multilayer printed wiring board 7 whose outermost layer is a metal foil for forming an outer layer circuit. The X-axis is taken on one side of the outer shape, and the Y-axis is taken on the side perpendicular to the side. Now, metal marks 8a, 8
Each coordinate on the XY coordinate system of b, 8c is (Xa, Ya),
(Xb, Yb), (Xc, Yc), inner layer circuit board 1
The inclination θ between the xy coordinate axes and the outer shape of the multilayer printed wiring board 7 is determined by the following formula.

θ=tan ^-1 (Xb-Xa/Yb-Ya) ... Also, the coordinates (Xo, Yo) on the XY coordinate system of the origin of the xy coordinates of the inner layer circuit board are determined by the following equations and formulas.

^{Xo ＝ _ _}
The XY coordinates (Xi, Yi) of b can be found using the following equations and expressions.

Xi=Xo+xisinθ+yisinθ...Yi=Yo−xisinθ+yicosθ...The XY coordinates (Xi, Yi) of the hole mark obtained in the above manner are input into the computer. Based on this information, a reference hole is automatically formed at a precise position on the outer layer metal foil by controlling a hole punching means provided to move according to the XY coordinates.

As shown in FIG. 5, a plurality of inner layer circuit boards 1, 1, 1 are arranged in a plane and are simultaneously molded integrally with the same outer layer material (prepreg and metal foil) 10 to form a multilayer printed wiring board. The above equations can also be applied when an intermediate product is formed and this intermediate product is roughly cut into each inner layer circuit board. In other words, multiple points on the cutting line during rough cutting
If the xy coordinates are determined in advance, the metal mark 8
As shown by the chain line, rough cutting can be performed while avoiding the parts a, 8b, 8c and the inner layer circuit 1a. The outer edge of the outer layer material is deformed during molding. Therefore, it is cut off by rough cutting.

In the method for detecting the position of a hole mark on a multilayer printed wiring board according to the present invention, the eddy current sensor does not directly detect the hole mark, but instead measures the position of another metal mark that serves as a reference for determining the coordinates of the hole mark. I try to do that. This is because the hole mark may be provided within the inner layer circuit pattern, in which case it is difficult to distinguish it from the inner layer circuit pattern. Furthermore, in the embodiment, the x-axis and y-axis, which serve as the reference for the coordinates of the hole mark, are determined using metal marks, so that the coordinates of the hole mark can be determined accurately.

In the embodiment, the position of the metal mark was measured based on the waveform peak point of the output of the eddy current sensor. This is because, based on the waveform peak point, measurement is possible regardless of changes in detection sensitivity due to differences in prepreg thickness, metal foil thickness, material, etc.

In the embodiment, the hole marks detected by the hole mark position detection method for a multilayer printed wiring board according to the present invention indicate the positions of reference holes 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 restriction on the position or number of hole marks formed. The same applies to metal marks. Therefore, the metal mark does not necessarily have to be located on the xy coordinate axes. The xy coordinate axes can be determined freely.

〔Effect of the invention〕

In the hole mark position detection method for a multilayer printed wiring board according to the present invention, metal marks are formed in advance at multiple locations on the periphery of the circuit pattern of the inner layer circuit board at the same time as the circuit pattern to serve as a reference for determining the coordinates of the hole marks. , an eddy current sensor is scanned from the edge of the surface of the outer metal foil to measure the positions of a plurality of metal marks based on changes in the output of this sensor, and the position of the hole mark is detected based on the measurement results. Since the detection is performed using an inexpensive device called an eddy current sensor,
The effect is that automation can be realized at low cost.

[Brief explanation of the drawing]

FIG. 1 is a sectional view illustrating a conventional method for detecting hole mark positions on a multilayer printed wiring board, and FIG. 2 is an embodiment of an inner layer circuit board used in the method for detecting hole mark positions on a multilayer printed wiring board according to the present invention. FIG. 3 is a diagram illustrating an embodiment of the hole mark position detection method for a multilayer printed wiring board according to the present invention, and FIG. 4 is a plan view of the multilayer printed wiring board shown in FIG. A drawing explaining a method for automatically replacing the hole mark position detected by the hole mark position detection method with the position on the outer layer metal foil. 2 is a diagram illustrating a method for performing rough cutting by applying a mark position detection method. 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, 8
a, 8b, 8c...metal mark, 9...eddy current sensor.

Claims (1)

[Scope of Claims] 1. A hole mark position detection method for detecting the position of hole marks in a multilayer printed wiring board in which hole marks indicating hole drilling positions are formed at appropriate number of locations on an inner layer circuit board, At the same time as the circuit pattern, metal marks are formed in advance at multiple locations on the periphery of the circuit pattern on the inner layer circuit board to serve as a reference for determining the coordinates of the hole marks, and the eddy current sensor is inserted from the edge of the outer layer metal foil surface. A hole in a multilayer printed wiring board, characterized in that the positions of the plurality of metal marks are measured based on changes in the output of the sensor in a scanning manner, and the position of the hole mark is detected based on the measurement results. Mark position detection method. 2 The metal mark serves as the reference for the coordinates of the hole mark.
A method for detecting the position of a hole mark in a multilayer printed wiring board according to claim 1, which is for determining an xy coordinate axis.