JPS6398188A - Method of detecting position of reference mark of multilayer printed board - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a method for detecting the position of a reference mark on a multilayer printed circuit board.

(b) Conventional technology Are there generally holes for wiring in multilayer printed circuit boards? - Drill a hole using an axial drill and fit the reference hole of the multilayer printed circuit board into the guide pin of the multiaxial ball holder in order to position the multilayer printed circuit board with respect to the six drills to be processed. Therefore, since the reference hole needs to be accurately provided at a predetermined position on the multilayer printed circuit board, the reference mark (copper mark) previously provided on the multilayer printed circuit board is detected, and the drill is drilled at the detected position. Processing equipment is used. However, in order to detect the fiducial mark of a multilayer printed circuit board that has a copper foil layer on the surface and a fiducial mark on the inner layer, X-rays are used to process the fiducial mark. There were disadvantages such as there was no other way to find the center position, the equipment was expensive, and it was not easy to do because there were legal regulations regarding the handling of X-rays.In order to solve this problem, the applicant First patent application 1986-238
89 was filed. This technology is a multi-layer printed circuit board with a pattern outside the inner layer on the same layer as the reference mark.
A reference copper foil wire is provided in advance at a predetermined relative position between the reference mark and the jll, and the position of the reference copper foil wire is first detected by moving the overcurrent type position sensor, and then the reference copper foil wire is detected. The position is detected by moving the eddy current position sensor toward the reference mark based on the relative position between the reference mark and the reference mark.Then, the sensor is moved in a direction perpendicular to the above movement direction to determine the coordinates of the reference mark. I try to ask for it.

(c) Problems to be solved by the invention By the way, the eddy current type position sensor cannot distinguish between a reference mark and a pattern other than the reference mark, so there is no reference mark in the detection operation path. There is a restriction that there must be no patterns other than marks, so
Considering errors in end face processing of multilayer printed circuit boards, it is necessary to maintain a sufficient distance between the reference mark and other patterns, but on the other hand, to avoid wasting expensive multilayer printed circuit boards, There is also a desire to minimize the distance between the two patterns.

However, the above method requires a reference copper foil wire, and therefore has the drawback of not being able to meet the above requirements. Also, if the distance from the reference mark to the end face of the board or the wiring pattern is set too small, the sensor may protrude outside the board and cannot perform a detection operation, or the sensor may enter the wiring pattern and cause erroneous detection. There was an inconvenience that it ended up happening. The present invention aims to solve these problems.

(d) Means for solving the problem The present invention stores in advance an approximate value from the end face of the multilayer printed circuit board to the position of the reference mark, and positions an eddy current position sensor at this (predetermined position). First, the detection movement of the reference mark is started in a direction in which the front and rear margins of the reference mark are larger than the left and right margins in the direction perpendicular to this, and the detection movement is performed in a direction parallel to this until the reference mark is detected. Then, the above problem is solved by performing a detection operation in a direction that is 45 degrees to this detection direction.That is, the multilayer printed circuit board fiducial mark-position detection method of the present invention uses a method in which a copper fiducial mark is provided in advance. A method for detecting the position of a reference mark on a multilayer printed circuit board in which another copper foil layer is provided on a copper foil layer, the distance from the end face of the multilayer printed circuit board to the position where the reference mark is provided is memorized in advance. Then, position the eddy current position sensor above this position, and first set the reference mark parallel to the end face of the multilayer printed circuit board in a direction where the front and rear margins of the reference mark are larger than the left and right margins in the direction perpendicular to this mark. If the mark detection operation is started and the reference mark cannot be detected, the detection operation is performed at a fixed interval along the trajectory of this operation, and this movement is repeated until the reference mark is detected. The positions of one end and the other end are detected, and the coordinates from the coordinates of the first position to the center of the reference mark are calculated using the signals of the two detected positions, and then,
Through this calculated coordinate point, the eddy current type position sensor is caused to detect ('f=') in an oblique direction with an angle of 45 degrees with the initial trajectory.

(E) Position the eddy current position sensor above the coordinates based on the stored data from one end of the multilayer printed circuit board to the center of the reference mark. In this state, move the eddy current position sensor in a direction where the front and back margin of the reference mark is larger than the left and right margin in the direction perpendicular to this, for example, in the lateral (X) direction,
Detect the reference mark. When the reference mark cannot be detected, detection operations are performed at regular intervals along the locus of the initial detection operation, and this operation is performed until the reference mark is detected. Changes in output voltage or current due to the eddy current position sensor passing over the reference mark (detect the position of one end of the reference mark from H, move the eddy current position sensor further in the same direction, and do the same) The open end position is detected. From these two values, the correct center distance in the X direction is determined. At this time, the approximate position (vote) in the vertical (Y) direction of the base 114 mark is also determined. By moving the eddy current position sensor in a direction that makes a 45 degree angle to the approximate coordinates, the distance between the base ψ mark and the edge of the board, or the distance between the reference mark and the wiring pattern can be determined. Even if the distance is small, the accurate center point of the reference mark can be determined as a result.

(F) Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 6 of the accompanying drawings.

FIGS. 1 and 2 show a reference hole machining apparatus for a multilayer printed circuit board for carrying out the method of the present invention. A drill head 10 provided with an eddy current position sensor 6 and a drill 8 includes:
It is attached to a table 14 movable in the X direction by a servo motor 12, and this table 14 is further provided on a table 18 movable in the Y direction perpendicular to the X direction by a servo motor 16. The operation of the servo motor 12 and the servo motor 16 is controlled by a controller 20, and the operation of the servo motor 12 and the servo motor 16 is controlled by a controller 20.
, i.e., the X direction and Y direction of the drill head 10
A signal corresponding to the directional coordinates is detected by, for example, a pulse detector provided thereon, and is input to the controller 20. In addition to inputting the detection signal of the eddy current type position sensor 6 to the controller 20,
Approximate value signals (two types of signals, X-direction data and Y-direction data) from this point to the center position of the cap mark 4 are also stored.

Next, the method of the present invention will be explained. Multilayer printed circuit board 2
For example, it has a four-layer structure, with the top and bottom outermost layers having a thickness of 2.
It is a copper layer with a thickness of about 0 tt, and a circular copper mark 4 serving as a reference mark is provided on the second layer from the top. Each layer is partitioned by a pre-pure plate 2c. Therefore,
The copper mark 4 on the second layer of the upper corner is not visible from the outside.

If the multilayer printed board 2 is made in large numbers, it is necessary to separate it, and if one piece is taken out, it is necessary to remove the protruding part of the buri-plave 2e and make the dimensions uniform, so in any case, the board Although the end face is cut,
As described above, since the reference mark cannot be visually observed, the cut is made without obtaining an accurate dimension from the center of the reference mark to the end surface of the substrate.

In advance, end surfaces 2 al, 2 of the multilayer printed circuit board 2
is stored in the controller 20.

With the multilayer printed circuit board 2 installed on a predetermined processing table,
The eddy current position sensor 6 is driven on the coordinate 4Z based on two approximate position signals from the controller 20 (FIG. 4).
. From this coordinate 4Z, the eddy current position sensor 6 is moved in a direction in which the front and rear margins of the reference mark are larger than the left and right margins in the direction perpendicular to this, for example, in the direction (X direction) orthogonal to the end surface 2al of the multilayer printed circuit board 2. The eddy current type position sensor 6 first performs detection movements in the X direction at preset intervals until it crosses a point 4xl on the circumference of the reference mark 4. When the eddy current position sensor 6 cuts a point 4xl on the circumference of the reference mark 4, the output current changes as shown in Figure 5. The coordinate value X1 indicating the pulse signal from the servo motor 12 at the point 4x2 is stored in the controller 20. Also, the eddy current position when moving to the right in FIG. The output current of the sensor 6 similarly changes as shown in FIG. 6, and the coordinate value X2 at the point 4x2 is stored.
At o, the calculation X=(xl+x2)/2 is performed. This X indicates the coordinate value of the center position of the i+4 mark 4 in the X direction. This X-direction alFt value and locus tM
Since the approximate coordinates in the Y direction can be determined using ft'f X 1 and X2, the approximate center coordinates of the copper mark can be determined. Next, the servo motor 12 and the servo motor 16 are operated to move the eddy current position sensor 6 in the direction shown by arrow #4 in FIG. let me,
The center position of the copper mark 4 in the 45 degree direction is calculated by the same operation as above. This means that a more accurate center position of the copper mark 4 has been calculated. In this way, when the rod moves in the Y direction, if the eddy current position sensor is operated in a direction perpendicular to this 45 degree direction (in the direction indicated by the two-dot chain arrow I+ in Fig. 3), more accurate detection can be achieved. It becomes possible to find the coordinates. Next, the servo motor 12
Then, the servo motor 16 is operated to move the drill 8 to this central position. That is, the detected copper mark 4
Since the eddy current type position sensor 6 coincides with the center position of the eddy current type position sensor 6, the servo motor 12 is operated to move the drill head 8 by a distance of 9 minutes between the eddy current type position sensor 6 and the drill 8. Thereby, the drill 8 is aligned with the center position of the copper mark 4. Next, the drill 8 is lowered and the reference hole is machined. In this way, a reference hole is accurately formed in the center of the copper mark 4. Since there is generally a plurality of reference holes, for example, by storing coordinate values from the first reference hole in the controller 20, it is possible to perform the following processing efficiently. Note that during the second-stage detection operation, driving in the 45-degree direction has the advantage that calculations for finding the center are the simplest, and the detection operation can be performed more efficiently than when other angles are selected.

(1.) As described in detail, according to the present invention, in the direction in which the distance between the reference mark and the end face of the board or between the reference mark and the wiring pattern is shorter, the distance between the reference mark and the wiring pattern is at an angle of 45 degrees. Since the detection operation is performed in the same direction, the detection operation can be performed without any problem even if the distance between the reference mark and the end face of the board or the distance between the reference mark and the wiring pattern is small.
It has become possible to economically use expensive multilayer printed circuit boards.

[Brief explanation of the drawing]

Figure 1 is a plan view showing the reference hole processing device, Figure 2 is a view seen in the direction of arrow 11 in Figure 1, Figure 3 is a diagram showing the relationship between the end face of a multilayer printed circuit board and the reference hole, and Figure 4. Figures 5 and 6 showing the trajectory of the wave mark and eddy current position sensor
The figure is a diagram showing changes in the output current of the eddy current type position sensor. 2...Multilayer printed circuit board, 4...Copper mark, 6...
・Eddy current position sensor, 8...drill, 10...
Drill head, 12... Servo motor, 14... Table, 16... Servo motor, 18... Table, 20... Controller. Figure 2

Claims (1)

[Claims] In a method for detecting the position of a fiducial mark on a multilayer printed circuit board in which another copper foil layer is provided on a layer on which a copper fiducial mark is previously provided, the fiducial mark is provided from an end surface of the multilayer printed circuit board. Memorize the distance to the position in advance, position the eddy current position sensor above this position, and first place the multilayer printed circuit board in a direction where the front and back margins of the reference mark are larger than the left and right margins perpendicular to this. If the reference mark cannot be detected, the detection operation is started parallel to the end face of the reference mark, and if the reference mark cannot be detected, the detection operation is performed at a predetermined interval along the locus of this operation, and this operation is continued until the reference mark is detected. The positions of one end and the other end of the reference mark are repeatedly detected, and the detected 2
The coordinates from the coordinates of the first position to the center of the reference mark are calculated using the signals of the two positions, and then a vortex passes through the calculated coordinate point and forms an oblique direction of 45 degrees with the initial trajectory. A method for detecting the position of a reference mark on a multilayer printed circuit board, characterized by operating a current-type position sensor.