JPS62127240A - Method of laminating and positioning green sheet - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] [Summary] In the green sheet stack alignment process, a plurality of specific pattern positions on the green sheet are imaged using an image input device, compared with a reference pattern, and n of each positional deviation error is calculated. The sum of the multiplications is calculated digitally and used as an alignment evaluation measure to align the stacked green sheets to improve work accuracy and efficiency.

(Industrial Application Field) It is related to the stacking alignment process of green sheets, which are the pre-fired forms of multilayer ceramic substrates for electronic circuits, and more specifically, the pattern of the green sheets is recognized by an image input device, and its position is The present invention relates to a method of comparing the position with a prescribed pattern and selecting the position with the minimum error by digital information processing.

The main steps from forming the tape-shaped green sheet to laminating it are shown in Figure 6.
(b) Via hole punching, (C) Via hole filling and pattern printing,
(D1 alignment lamination. Although not shown, the laminated green sheets are then pressed into close contact and then fired.

The via hole is a hole with a diameter of 70 to 120 microns,
It is filled with a conductive material to provide electrical continuity between the upper and lower surfaces of the sheet. Therefore, the green sheet must be stacked in such a manner as to match the specific pattern position of the green sheet below or above the green sheet.

For this reason, there has been a demand for the development of a method that allows simple and accurate positioning.

[Prior art and problems to be solved by the invention] The conventional alignment of green sheets is shown in FIG. - Show a plurality of reference holes 20 in the laminating jig 22? ! This was done by inserting it into the losing guide pin 23.

However, with this method, inserting multiple reference holes correctly and perpendicularly to the position of the guide pin requires extremely sophisticated technology and time, and the reference holes may be distorted due to the The variation in position could be as much as 200 microns.

The present invention was devised in view of these points.
The object of the present invention is to provide a green sheet stacking alignment method that allows quick and accurate alignment with an easy-to-operate configuration.

[Means for solving problems]

For example, a green sheet is imaged by an image input device such as a television camera, and a contour detection unit detects contours of a plurality of predetermined patterns on the green sheet and contours of a predetermined reference pattern corresponding to the patterns; Furthermore, the coordinate gap between both contours is determined by counting clock pulses in both the X and Y directions, and the absolute value of the difference between the gap values on both sides of the specific pattern is calculated for all specific patterns. The above problem can be solved by summing the n-th power of the absolute values for all specific patterns in both the X and Y directions and aligning the green sheets using the total value as an evaluation standard.

[For production]

For example, identify two via holes located diagonally apart on the green sheet, and draw two white circles or squares slightly larger than the via holes at the correct positions. , set as a reference pattern.

First, while displaying a reference pattern on an image display device, an image of the pattern surface of the green sheet is taken, the image is superimposed on the display screen, and the green sheet is moved manually or by other methods while looking at the image. Then, bring the via hole set above into the reference pattern.

In this state, alignment according to the present invention is started.

Note that the via holes and patterns on the green sheet can be clearly distinguished from the background on the image capture screen, so for convenience of explanation from now on, the background part will be shown as white, and the part without the reference pattern and the via holes will be shown as black.

1 The scanning line in the X direction passing through the center of the reference pattern is X-X'
Then, the video output signal of the scanning line changes from black to white at point p in FIG. 3, black at point q, white at point r, and black at point S. The number of pixels during the period in which the signal is white represents the distance of the gap between the aligned pattern and the reference pattern. Therefore, in terms of an electronic circuit, the value of the gap can be determined by the number of pulses of the pixel scanning clock during the gap period.

1. Count the number of clock pulses a1 and l in the gaps on both sides of the specific pattern, and calculate the absolute value Δ3 of the difference between them. -a+
-a, + are calculated, the gap of another reference pattern is determined as a2, a2' by the same process, and the absolute value Δa2 of the difference is calculated.

Next, regarding the vertical direction, as shown in FIG. =
/l, detects whether the video signal of the pixel is black or white, and
While scanning in the Y direction, the gap period from when the video signal changes from black to white at the outline of the reference pattern until it changes from white to black at the boundary of the pattern to be aligned. Count the number of pixels, that is, the number of scanning lines in the X direction in this case, and set them as b1 and b+', respectively, as in a, calculate the absolute value of the difference Δb+, and similarly calculate it for another reference pattern. b,' and Δb2,
S-Δa, n +Δaz″I +Δb, 1) +Δ
Calculate btn. A positive value of 1 or more is selected as the value of n. This total value S becomes O when the pattern to be aligned is located at the center of the reference pattern, and the value increases when the position shifts slightly, so the total value S is an evaluation measure of the quality of alignment. It is very effective as

The holder that holds the green sheet has a structure that can be finely adjusted in the XY direction and the rotational direction θ by a drive device 13, and the coordinates in these three directions can be read out.

Therefore, the position of the holder is changed a predetermined number of times, each sum value S at each position is determined, and the 3N LQ sum value S is stored in the storage unit in correspondence with the holder coordinate values in the three directions. do. Thereafter, the coordinate value of the holder corresponding to the lowest value of S is retrieved from the storage section, and the holder driving device is driven to move the green sheet to the coordinate value.

〔Example〕

The gist of the present invention will be specifically explained below with reference to embodiments shown in the drawings. The same reference numerals indicate the same objects throughout the figures.

FIG. 1 is a block diagram showing the configuration of one embodiment.
is a camera as an image input device, 4 is a reference pattern generator, 5 is a scan control unit, 6 is an X-scanning direction contour detection unit, 7 is a Y-direction contour detection unit, 8 is an X-coordinate gap counter, and 9 is a Y-direction Coordinate gap counter, 10 is a calculation unit, 1) is an image display device,
1) -1 is a display section, 12 is a standard comparison section, 13 is a holder drive device, 14 is a storage section, 15 is a check number counter, 1
6 is a search control section, and 17 is a starting circuit. All of these can be constructed using known conventional techniques and are easily available. Figure 2 shows the display screen, in which 1)-2 is the display screen, 17 is the green sheet,
2 is a specific via hole selected for alignment, 3 is a reference pattern, X-X' and Y-Y' are horizontal and vertical scanning lines passing through the center of the reference pattern, respectively, and the arrow indicates the holder driving device 1.
The moving direction X1Y and rotation direction θ of the green sheet according to 3.
shows.

FIG. 3 is a signal waveform diagram, in which the horizontal axis represents the dimensions of only the topmost pattern, and the others represent the time corresponding to the horizontal scanning XX' of the pattern. In the center is shown the clock pulse that sends the video signal, which is the output of the image input device, to the horizontal pixels below.

FIG. 4 is an explanatory diagram of Y-direction scanning, and FIG. 5 is a flow diagram.

The present invention will now be described in detail. By manual or mechanical means, two specific via holes on the green sheet are brought into the reference pattern 3 while looking at the image display device 1), and then the alignment of the present invention is started.

As shown in Fig. 3, the output video signal of the horizontal scan X-X' changes from black to white at the left side outline p of the reference pattern 3, from black at the left ring ItSq of the via hole 2, and from black at the right side outline r of the via hole 2. X
The direction contour detection section 6 detects the direction contour.

Since the white part indicates the gap between the reference pattern and the outline of the via hole, the number of clock pulses that send horizontal scanning pixels is counted by the coordinate difference value counter 8 during the period when the video signal output is white. , the number of pixels, that is, the gap distance can be obtained. The pulse number counting result number is a as shown in the figure.
l, 81°, and the absolute value of their difference Δa1= a
1-a,'' is calculated.

Similar operations are performed for other reference patterns, and azs
Obtain a2' and calculate Δaz=ax-82'.

Next, we will discuss the vertical direction. As shown in Figure 4, 1
Taking the Y-direction scanning line Y-Y' passing through the center of the reference pattern, the scanning control 5 points out the pixel at the point where the X-direction scanning line intersects Y-Yo at x = A, and detects the Y-direction contour. The unit 7 detects whether the video signal of that pixel is black or white, and in the same way as it did in the X direction, at the outline of the reference pattern 3,
The Y-coordinate difference value counter 9 counts the pixels, in this case the number of scanning lines in the X direction, during the period from when the video signal changes from black to white until it changes from white to black at the outline of the via hole 2. , their numbers are respectively b+, b+' as in a, the absolute value of their difference Δb1・b+-b+' is calculated, and the same for another reference pattern is bt, bz', and the difference between them is Calculate the absolute value Δb2・b2~b,l,
Assuming n=1, S-Δa1+Δa, +Δb, +Δb
Calculate t. The calculations of Δa, to Δb8 and S are performed by the calculation unit 10.

The calculated i, θ sum S is displayed on the display section 1)-1 and simultaneously inputted into the standard comparison section 12, and if it is within the standard value, alignment is completed. Alternatively, even if it is within the standard value, if the position with the minimum error is to be pursued, the method described below is further performed.

The drive device 13 of the holder that holds the green sheet is
It has a structure that allows highly accurate position adjustment using a micrometer in the Y direction and rotational direction, and allows the coordinates in these three directions to be read out.

The total sum value S is stored in the memory in correspondence with the coordinate values of the holder driving device 13 in the three directions. Furthermore, the number of checks is counted by the check number counter 15, and while the green sheet is moved and rotated manually or mechanically a predetermined number of times, the total sum S is calculated and the coordinate values of the holding body are stored in the storage section in the same manner as above. 14, and then the search control section 16 searches for the coordinate value corresponding to the lowest value of the total sum S, displays the search value on the display section 1)-1, and displays the holder driving device at that position. 13 to move the green sheet. In this case, the green sheet may be moved manually by reading the lowest value coordinates from the display screen, but it is also easy to automatically drive the holder driving device 13.

By the method of this invention, the alignment error, which conventionally reached 200 microns, can be reduced to about 10 microns.

In this embodiment, alignment was performed at two via holes, but it is of course possible to perform alignment at more locations, which is also preferable for improving alignment accuracy. Further, although via holes are used as a reference for alignment, other patterns may of course be used.

The reference pattern is stored in the reference pattern generating section 4 in advance (however, as an alternative method, the reference pattern may be imaged with a camera and superimposed on the screen when the device is used. Not only a circle but also a square shape is used.

In obtaining the above calculated value S, 1 was used for n, but it goes without saying that a larger number may be used.

The larger n is, the higher the alignment sensitivity becomes.
The burden on 0 will increase.

Calculation and display of S can also be performed independently in the X direction and Y direction.

A part of the image display device 1) can be used as the display section 1)-1.

Although the entire green sheet 17 is shown in FIG. 2, it is also possible to enlarge and display only the reference pattern part. In that case, the accuracy of alignment increases in proportion to the magnification.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to align the green sheets by extremely easy operation of the hour wheel, which contributes to improving the accuracy and reducing the number of man-hours, and also makes it possible to further increase the packaging density. , its practical effects are enormous.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of one embodiment of the present invention, Figure 2 shows the display screen; Figure 3 is a signal waveform diagram, Figure 4 is an explanatory diagram of the vertical coordinate gap, Figure 5 is a flowchart, FIG. 6 shows a conventional process. In the figure °ζ, 2 is a specific via hole, 3 is a reference pattern.

Claims (2)

[Claims] (1) In the green sheet stack alignment process, multiple specific patterns on the green sheet (2)
is imaged by an image input device, the outline of the pattern is scanned in the main scanning direction and the sub-scanning direction, and a reference pattern (3) is created corresponding to the above-mentioned specific pattern.
Detect the contours on each of the above scanning lines, calculate the gap between the two contours on each scanning line, and calculate the absolute value of the difference between the gaps on both sides of each specific pattern (2) on each scanning line. A method for stacking and aligning green sheets, characterized in that a specific pattern is calculated, a sum S of the absolute values of the gaps to the nth power is calculated, and alignment is performed using the sum S as an evaluation measure. (2) Change the position of the holding body that holds the green sheet a predetermined number of times, calculate the above-mentioned summation value S at each position, and calculate the vertical, horizontal, and rotational coordinate values X at each position of the holding body,
Y, Θ and the total sum value S are stored in a storage device, and the coordinate value corresponding to the minimum value is searched from the total sum value S stored in the storage device, and the coordinate value corresponding to the minimum value is searched. 2. The green sheet stack alignment method according to claim 1, wherein the green sheet position is determined by moving the holder to the position of the search coordinate value.