JPS62166914A - Reference hole drilling device for multilayer printed board - Google Patents

Abstract

PURPOSE:To drill a standard hole on a printed board in a highly accurate manner, by forming a hole mark, showing a reference hole drilling position, in a proper spot on an internal layer circuit board, and shifting the reference hole to a central position of the hole mark by a picture processing device. CONSTITUTION:Part of an upper spot facing hole 12c of a plate 7, whose spot facing from both sides of a multilayer printed board 7 is finished, is moved to a lower part of an industrial television camera 21. Next, light is illuminated from the lower slant of this hole 12c by optical fibers 20 and 20, and the light transmitted image appearing in this hole 12c is photographed by the ITV camera 21, then this image is subjected to a picture process by a picture processor 29. With this constitution, a center point of a hole mark is directly taken out, thus a reference hole's drilling position is detected in a highly accurate manner without entailing any errors.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a device for punching reference holes in a multilayer printed wiring board.

[Background Art] Multilayer printed wiring board plates used in electronic devices and the like are generally manufactured as follows. First, metal foil is pasted on both sides or one side of an inner layer prepreg, and an inner layer circuit is formed thereon to produce an inner layer circuit board. Then, prepregs for the outer layer are superimposed on the top and bottom of the inner layer circuit board or a plurality of inner layer circuit boards arranged in a plane, and metal foil is further superimposed on the outside of these, followed by heating and pressure forming. .

After that, if one or more inner layer circuit boards are arranged in a plane, rough cutting is performed for each inner layer circuit. By the way, in the intermediate product of the multilayer printed wiring board produced after the above-mentioned molding, the hole mark displayed on the surface of the inner layer circuit board for indicating the position of the reference hole is detected from the outermost layer metal foil side.

A spot with a hole mark is counterbored from above to expose the hole mark, and a reference hole is drilled 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 method has the following problems. In intermediate products of multilayer printed wiring boards that are composed of a plurality of inner layer circuit boards arranged side by side,
Since the inner layer circuit board is hidden from view by the outermost layer of metal foil, it is difficult to determine the rough cutting position.b. When trying to find the hole mark, the hole mark is blocked by the outermost layer of metal foil. The exact position of the hole mark is becoming increasingly difficult to determine because the hole mark cannot be seen and the exact position cannot be determined, and because positional deviations tend to occur between the outer layer and the inner layer circuit board during C1 heat and pressure molding. It is α that there is.

Therefore, in order to solve the above-mentioned problems, the following hole mark detection method has been devised.

In other words, after forming the inner layer circuit C and hole mark B on the inner layer prepreg, with a patch (id mark) pasted on the hole mark B in advance, the outer layer prepreg D and metal foil E are stacked and heated and pressed. The intermediate product of the completed multilayer printed wiring board is raised by the thickness of the patch, and the part on the metal foil is visually determined to be slightly shiny. Thereafter, the determined position is counterbored to make a counterbore hole A as shown in FIG. 9(a), and then the patch is peeled off to expose the hole mark Bt-as shown in FIG. 9(b).
In this method, the adhered resin is further polished to clearly expose the peeling hole mark B, and the center position X of the hole mark B is determined using a magnifying scope.

However, this method also requires a patching process.

Moreover, since the counterbore position is detected by visual inspection, it is difficult to drill the counterbore in an accurate position, and furthermore, the depth of the counterbore hole A is t. Since this was determined by the operator's intuition, it required considerable skill to counterbore to the appropriate depth. Therefore, counterbore and drill holes have a problem of low positional accuracy and lack of reliability.

Furthermore, as described above, the resin adheres to the hole mark surface, which poses an aesthetic problem, and the holes also cause a decrease in positional accuracy. Furthermore, in addition to the process of pasting patches to indicate the hole mark positions as mentioned above, counterbore work, polishing to remove adhering resin, and manual work called saku-qin are required for making holes, so the accuracy of each work may be affected. However, there were quality problems, and it was extremely labor-intensive and difficult to ensure final accuracy. In other words, since it was considered difficult to automate the process while ensuring accuracy, the process relied on the manual process described above, but in the end it was unreasonable in terms of quality and cost.

[Object of the Invention] The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a device for punching reference holes in a multilayer printed wiring board, which is automated at low cost and has high accuracy in the positioning of nine reference holes. It is on offer.

[Disclosure 1 of the Invention The present invention provides a circuit pattern in which a hole mark indicating a reference hole drilling position is formed at an appropriate location on an inner layer circuit board, and an edge mark is formed on the surface of the inner layer circuit board to predict the formation position of the hole mark. An eddy current sensor detects the position of an edge mark by scanning the surface of the multilayer printed wiring board based on a change in eddy current loss, using a multilayer printed wiring board formed of metal foil on the peripheral edge of the multilayer printed wiring board; a prediction means for predicting the position of the hole mark from the detection position from the equation sensor; and a counterbore hole of a constant depth that is moved to a predetermined position on the upper and lower surfaces of the multilayer printed wiring board based on the prediction result of the prediction means. Upper and lower end mills for drilling, a light projecting means for irradiating a light beam onto either the top or bottom of the multilayer printed wiring board drilled by these end mills, and a seat from the opposite light projecting side. an imaging means disposed corresponding to the borehole to take a light transmitted image; an image processing means for determining the center position of the hole mark from the image obtained by the imaging means; and an imaging means for determining the center position of the hole mark from the image obtained by the imaging means; A special embodiment will be described below, which is characterized in that it is provided with a drill device that is moved to a central position and drills a reference hole in a multilayer printed wiring board.

Figure 1 shows an inner layer circuit board 1 used in this embodiment.
The inner layer circuit board 1 has hole marks 1t+, i b at the peripheral edge afi of the circuit pattern 1a having the hole mark 1b.
, ib, and metal edge marks 8a, 8b, and 8c are formed at the same time as the circuit pattern 1a, respectively. These edge marks 8a, 8
b, 8c are X of the inner layer circuit board 1 as shown in FIG.
This is for determining the yy reference axis, and the edge mark 8a
Let the straight line passing through the center points of and edge mark 8b be y pongee,
The x-axis is a straight line that is perpendicular to the y-pongee and passes through the center point of the edge mark 8C. The coordinate position of each hole mark 1b is determined according to these xyy reference axes. Edgemark 8
For at a b and 8 c, as shown in FIG. 2, the eddy current sensor 9 is placed inward (in the direction of the arrow, also shown in FIG. 1) while keeping a certain distance from the surface of the outer layer metal foil 5. Position measurements are made in a scanning manner. Electrical conductors are detected by utilizing the change in impedance of the sensor coil due to eddy current loss. In this example, the outer layer gold s? Since the eddy current loss due to i is constant,
The change in eddy current loss when the outer layer metal foil and the metal edge mark overlap is detected. As shown in the graph of tjfJ2, the eddy current sensor 9 scanning the surface of the outer metal foil 5 detects the edge mark 8 where the first magnetic field change occurs.
When placed on at 8 b, 8 c, the sensor output forms the first waveform peak point A. Therefore, the first waveform peak point A of the eddy current sensor 9
The position of each of the plurality of edge marks 8a, 8b, 8c is measured based on the output change to form .

Then, the xyy reference axes defined on the inner layer circuit board 1 can be assumed on the surface of the outer layer metal foil 5. Therefore, each hole marker 2 whose coordinates have been determined in advance along the xyy reference axis
The position of 1b on the surface of the outer metal foil 5 can also be automatically determined.

FIG. 4 shows the overall system of the embodiment device, in which the detection signal obtained from the eddy current sensor 9 is processed by the central processing unit 31 via the signal processing circuit 30, and the position of the hole mark is detected. . Next, under the control of the central processing unit 31, a counterboring process is performed at that position. During the counterboring process, the xysi board on the inner layer circuit board 1 of the hole mark 1b is placed on the outer layer metal foil. It is automatically replaced at the corresponding position through calculation processing, etc. For example, as shown in FIG. 3, the XY coordinate axes are placed on the outline of the roughly cut multilayer printed wiring board 7 whose outermost layer is the metal foil of the outer circuit forming layer. Take an X pongee on one side of the outline, and take a Y pongee on the side perpendicular to the - side. And now Etsuno Mark 8 a, 8
b, 8 Each coordinate on the XY coordinates of c is (Xa, Y
a), (Xb, Yb), and (XetYc), the inclination θ between the xy coordinates of the inner layer circuit board 1 and the outer shape of the multilayer printed wiring board 7 is determined by the following equation 0.

The above coordinates (X o , Y o ) are calculated using the following formula 0 and 0
It is determined by the formula.

X o= X bcos2θ−YbSinθCOSθ+
Xcsinθe09θ+Yb5in2θ+X
csinθe09θ10Y ccos2θ・・・・・・■
Therefore, the xy coordinates of the hole mark 1b that have been determined in advance are (Xi
+yi), then the XY position f of the hole mark 1b to be found
f(Xi, Yi) is determined by the following formula 0 and (■).

X i = X o + xicos θ + yisin θ...
・・・■'1' i= Yo−xisinθ+yico
sθ...0 The XYjl[(X i, Y i) of the hole mark 1b obtained in the above manner is input to an arithmetic control means such as a computer, and based on that information,
By controlling the counterbore means provided to move relatively according to the Y coordinate, the counterbore hole is formed outside the metal f.
It is automatically formed at a position on f1s.

In addition, in the above embodiment, the metal edge mark 8
The number of edge marks 8 a, 8 b, and 8 c formed is not particularly limited, and the positions of edge marks 8 a, 8 b, and 8 c do not have to be located on the xy coordinates.

Pt45 shows the detailed structure of the counterbore means, in which the multilayer printed wiring board 7 is placed on an XY table 32 that operates based on the XY coordinate system. This XY table 32
is controlled by a drive signal from the drive controller 33 based on a signal from the central processing unit 31, and moves the multilayer printed wiring board 7 to the counterbore location. At this spot facing point, the end mill 12a serving as a spot facing means is provided on both the upper and lower sides of the table 11.
, 12b, and the lower end mill 12b is mounted on the stand 11.
A hole 11a is formed into which the receiver is inserted. Then, the end mill 12a is lowered from above by a drive signal from the drive controller 34 based on a signal from the central processing section 31, and a counterbore hole 12c is formed as shown in FIG.

FIG. 8 shows a top view of the counterbore 12c. At this time, the counterbore depth is determined by using the downward displacement of the end mill or the passage of time after the contact signal between the metal foil 5 and the end mill 12a is output by the continuity detector 28. control. Next, at the same position, the drive controller 34 of the lower end mill 12b is raised to form the counterbore hole 12c, and the counterbore depth t2 is controlled in the same manner as the upper endmill 12a.

At this time, the distance t between the bottom surface of the upper dust hole 12c and the hole mark 1b is preferably about 0.1 to 0.1 mII, and the counterbore depth t++h is preferably about 0.25 mm. The airtight chamber 13 is communicated with a dust collection path 13b for collecting dust etc. inside, and a rubber material 14 is provided around the opening to improve airtightness. Contact pin 15 for connection to 12a, pin 15a, and these contact pins 15
, and a spring 16.16a that biases the bottle 15a downward. A brush 17 connected to a continuity detector 28 is in sliding contact with a rotor 18 which is rotationally driven by a timing belt 19 and rotates an end mill 12a, and this brush 17 is held by a brush holder 17a.

Now, when the counterbore processing from the front and back sides of the multilayer printed wiring board 7 is completed, the upper dust hole 12c portion of the multilayer printed wiring board 7 is moved below the ITV camera 21 as shown in FIG. 7 using the XY table 32. let At this time, the lower dust hole 1
2c is applied obliquely from below through an optical fiber 20.20, and an ITV camera 21 captures a light transmission image appearing on the bottom surface of the upper dust hole 12c, as shown in FIG. this,
If the light transmission image is image-processed by the image processing device 29, the center point 26 of the hole mark 1b is directly derived, so that the central processing unit 31 can detect the drilling position of the reference hole with high precision without error. It is.

The image processing device 29 binarizes the video signal obtained by capturing the image and displays it on the monitor 35, and also sends it to the central processing unit 31, where the binarized image data is Then, the center coordinates of the drill hole marker 21b are determined by a conventionally known method such as the centroid measurement method or the long side 1/2 division method, and the XY table 32 is set so that the drill 22 is located below the center coordinates. The multilayer printed wiring board 7 is moved by controlled driving. After that, the actual drilling begins. As a result, a reference hole with extremely high positional accuracy can be obtained.゛In this case, the drill rotating section is attached to another fine movement XY table 36, and the fine movement XY table 36 is controlled and driven by the drive signal of the drive controller 37 based on the signal from the central processing unit 31, so that the center axis of the drill 22 can be adjusted. It may be arranged to match the center position of the hole 21b.

Incidentally, sometimes the multilayer printed wiring board 7 is placed on the stand 11 and pressed from above by the pressing member 23, so that the front side is set in a sealed state. A transparent glass 23b is fitted on the upper surface of the holding member 23, and the ITV camera 21 captures a light transmission image through the transparent glass 23b. In addition, chips generated when drilling a hole with the drill 22 are blown away by the air jet passage 23a, and the chips are blown away by the dust collection passage 25.
recovered by.

Now, in the above embodiment, Edgemark 8a, 8b...
・The process from detecting the position of the hole mark 1b to drilling the counterbore hole 12c is described, but the outline cutting of the printed wiring board is automatically cut by detecting the edge mark and finding the coordinates of the point of the cutting line. Of course, a step for performing this may also be provided.

[Effect of the invention 1] The present invention forms a hole mark indicating the position of the reference hole at an appropriate location on the inner layer circuit board, and also forms an edge mark on the surface of the inner layer circuit board to predict the formation position of the hole mark. an eddy current type sensor that detects the position of an edge mark by scanning the surface of the multilayer printed wiring board by using a multilayer printed wiring board formed of metal foil on the peripheral edge of the circuit pattern, and detects the position of an edge mark based on changes in eddy current loss; A prediction means for predicting the hole mark position from the detection position from the eddy current sensor, and a seat at a constant depth that is moved to a predetermined position on the upper and lower surfaces of the multilayer printed wiring board based on the prediction result of the prediction means. Equipped with upper and lower end mills for boring holes, it is possible to automatically drill counterbore holes, and moreover, it is possible to obtain counterbore holes of reliable depth and to prevent variations in the finish of the bottom of the counterbore holes. The exterior appearance is improved as it can be unified without using these end mills, and it also has a light projecting means that irradiates the light beam to the counterbore holes on either the top or bottom of the multilayer printed circuit board drilled with these end mills, and a counter-light projecting means. The center point of the hole mark is determined by the image pickup means arranged corresponding to the counterbore hole from the side and for taking a light transmitted image, and the image processing means for determining the center position of the hole mark from the image obtained by the image pickup means. It can be detected automatically with high accuracy, and therefore a reference hole can be drilled at a highly accurate position by a drill device that is moved to the center position of the hole mark determined by the image processing means. Due to automation, it is possible to obtain precision that cannot be obtained from manual or visual work, greatly improve productivity, and improve the finish of the product.Furthermore, it eliminates the need for patch application, which reduces scratches and scratches caused by patch application work. This has the effect of eliminating defective factors such as foreign matter contamination, greatly reducing the incidence of serious defects in multilayer printed wiring boards such as disconnections and short circuits that occur due to these factors, and producing products with high M conformity.

[Brief explanation of drawings]

FIG. 1 is a plan view showing one aspect of the inner layer circuit board of the multilayer printed wiring board used in the embodiment of the present invention, FIG. An explanatory diagram of a method for automatically replacing the hole mark position with the position on the outer layer metal foil, Fig. 4 is a schematic configuration diagram of the entire system as above, Fig. 5 is a cross-sectional view of the end mill part as above, Fig. 6 7 is a cross-sectional view of the spot-bored hole part of the multilayer printed wiring board obtained by the same end mill, and FIG. Figure 8 is an enlarged plan view of the counterbore hole according to the above, Figures f59 (a) and (b) are cross-sectional views and plan views of the counterbore hole part of the multilayer printed wiring board according to the conventional example, 1 is an inner layer circuit board, 1a is an inner layer circuit, 1b is a hole mark, 5 is an outer N metal foil, 7 is a multilayer printed wiring board, 8 at 8 b, 8
c is machining 7 mark, 12a*12b is end mill, 12
20 is an optical fiber, 21 is an rTV camera, 26 is a hole mark center position, and 29 is an image processing device. Agent Patent Attorney Ishi 1) Ai Figure 7 Figure 1a C Figure 2 Figure 3 Figure 4 Figure 7 Figure 2q Figure 8

Claims (1)

[Claims] 1) A hole mark indicating the position of the reference hole is formed at an appropriate location on the inner layer circuit board, and an edge mark to predict the formation position of the hole mark is formed on the surface of the inner layer circuit board.A metal is attached to the peripheral edge of the circuit pattern. An eddy current sensor uses a multilayer printed wiring board made of foil and detects the position of an edge mark by scanning the surface of the multilayer printed wiring board based on changes in eddy current loss; A prediction means for predicting a hole mark position from a detection position; and a surface for drilling a counterbore hole of a constant depth by being moved to a predetermined position on the upper and lower surfaces of a multilayer printed wiring board, respectively, based on the prediction result of the prediction means. , a lower end mill, a light projecting means that irradiates a light beam to a counterbore hole on either the upper or lower side of the multilayer printed wiring board drilled in these end mills, and a counterbore hole that corresponds to the counterbore hole from the opposite side of the light projector. an imaging means arranged to take a light transmission image; an image processing means for determining the center position of the hole mark from the image obtained by the imaging means; and a movement to the center position of the hole mark determined by the image processing means. 1. A device for drilling reference holes in a multilayer printed wiring board, comprising: a drill device for drilling reference holes in a multilayer printed wiring board.