JP2005523820A - Marking correction method for laser marking system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a marking correction method for a laser marking system which detects an alignment error of each chip and performs marking in consideration of a marking error at the position of each chip.
The present invention relates to a marking correction method for a laser marking system. The disclosed marking correction method of the laser marking system includes (a) assigning an observation target chip to each vision camera, (b) matching the coordinates of each vision camera and the laser marker, and (c) each chip or Marking a first symbol at a position corresponding to each chip, observing the first symbol selected by the vision camera, and teaching one point of the symbol as a reference point; and (d) the chip at the vision camera. Observing the first symbol and reference point and marking each chip with a second symbol on the basis of the reference point; and (e) observing the second symbol on the selected chip and comparing the symbols. Teaching a point; (f) detecting the position of the comparison point from the reference point on each chip and Comprising the steps of detecting the marking errors, the.

Description

  The present invention relates to a marking correction method of a laser marking system using a vision camera, and more particularly to a marking correction method of a laser marking system that corrects a marking object in consideration of a marking error stored in advance while imaging a marking object.

  FIG. 1 is a schematic plan view of a typical lead frame strip. Referring to the drawing, a plurality of chips 12 are mounted on one strip 10, and letters and / or numbers are displayed on the surface of each chip 12 in order to distinguish the chips 12 by production lot. At this time, a laser marker equipment (described later) using a laser beam is used as equipment used for marking. Here, 14 is a recognition tag, which is a label used for aligning strips.

  Such a marking process using a laser marker on the strip 10 tends to be an automatic process including handling of the strip 10 in order to improve the marking efficiency.

  FIG. 2 is a schematic diagram of a typical laser marking system.

  Referring to the drawings, the laser marking system includes a strip supply magazine 20 in which a plurality of strips 10 are stacked, a loader 30 that draws one strip 10 from the magazine 20 and aligns it with a horizontal transfer table 22, and the strip 10. A pre-vision camera 40 for measuring the alignment state, a step motor 50 for moving the strip 10 on the horizontal transfer table 22 in one direction, and marking characters on a plurality of chips on the strip 10 transferred below A laser marker 60, a post vision camera 70 for imaging the marking on the marked strip 10, and an unloader 80 for unloading the marked strip 10 to the strip collection magazine 90.

  The strip 10 placed on the horizontal transfer table 22 by the loader 30 is imaged by the prevision camera 40. In such a strip 10, a recognition tag (a strip itself or an etching line) is formed on one side of the strip 10 so that the alignment state can be easily determined. Only the strips 10 aligned by the pre-vision camera 40 are guided to the next marking step, and the misaligned strips 10 are bypassed and loaded again into the strip supply magazine 20 or discarded.

  The arm 52 is accurately driven by the step motor 50 so that the strip 10 on the horizontal transfer table 22 is positioned at a predetermined position, that is, below the pre-vision camera 40, the laser marker 60 and the post-vision camera 70.

  FIG. 3 is a drawing showing a schematic configuration of a laser marker. Referring to FIG. 3, a laser marker 60 includes a laser oscillator 61, a galvano scanner 63 that scans a laser beam in a XY direction in a predetermined region, and an incident laser beam having the same size with respect to the entire processing region. And an F-theta lens 64 for forming a focal point. 63a and 63b reflect incident laser beams as x and y mirrors, respectively, and each mirror is connected to a driving driver (not shown) and changes its angle according to an input command.

  The strip 10 on which predetermined characters are marked by the laser marker 60 is transferred to the lower side of the post vision camera 70 which is the next step. The post vision camera 70 images the strip 10 to determine the marking quality, bypasses the strip with the wrong marking, and loads the correctly marked strip on the strip collection magazine 90 by the unloader 80.

  FIG. 4 is a plan view for explaining a general tray 16 and a chip c located therein. Referring to FIG. 4, the tray 16 is partitioned into cells in which the chips c are placed so that a plurality of chips c are located. Since the size of this cell is slightly larger than the size of the chip, the chip in each cell can move when the tray 16 is transferred. Therefore, when each chip in the tray 16 is marked with the laser marker, if each chip is not aligned, the position of marking for each chip changes. Therefore, if the marking position is not constant, the consumer cannot be relied on the quality of the chip itself, causing dissatisfaction.

  When marking the chips on the strip, it is possible to mark by marking only the misalignment of the strip with the prevision camera, but when marking the chip in the tray, it was misaligned in each cell When marking a chip in a state by the above method, there arises a problem that the marking quality is remarkably deteriorated.

  The present invention was created to improve the above-mentioned problems, and an object of the present invention is to detect a laser alignment error by detecting the alignment error of each chip and taking into account the marking error at the position of each chip. A marking correction method for a marking system is provided.

  In order to achieve the above object, the marking correction method of the laser marking system according to the present invention includes a laser marker for marking while observing a chip loaded in each cell of a tray with at least one vision camera, and detecting a marked error. A marking correction method of a laser marking system comprising: (a) assigning an observation target chip to each vision camera; and (b) matching coordinates of each vision camera and laser marker; (C) marking each chip or a predetermined first symbol at a position corresponding to each chip, observing the first symbol selected by the vision camera, and teaching one point of the symbol as a reference point; (D) In the vision camera, the chip Observing one symbol and a reference point and marking each chip with a second symbol on the basis of the reference point; and (e) observing the second symbol on the selected chip and teaching a comparison point of the symbol. And (f) detecting a position of the comparison point from the reference point on each chip and detecting a marking error in each cell.

  In the step (a), (a1) a step of attaching a marking sheet to the surface of the tray or a plate having the same shape as the tray and disposing it below a plurality of vision cameras; and (a2) placing the laser marker in each cell with the laser marker. Preferably, the method includes: marking a point; and (a3) assigning a vision camera that looks for the point with the vision camera and observes each cell.

  The one point in step (a2) is preferably the center point of the cell.

  The step (b) includes: (b1) marking an outer edge point of the cell area with the laser marker as a reference, and (b2) detecting the position of the edge point with the vision camera to detect the laser marker. And the step of matching the coordinate system of the vision camera with the coordinate system of the vision camera.

  In step (c), an edge of the first symbol is pointed with a pointing device while viewing the first symbol on the display. In step (e), the second symbol is connected to the post vision camera. The edge of the second symbol is pointed with a pointing device while viewing the image.

  On the other hand, the present invention includes (g) a step of placing a tray loaded with chips to be marked below the vision camera, and (h) marking a point on the chip by observing the chip selected by the vision camera. Teaching as a reference point; (i) calculating each chip's alignment error by imaging each chip with the vision camera; and (j) using the marking reference point of each chip as a reference and the marking error and It is preferable that the method further includes a step of marking by correcting the alignment error.

  In the step (h), it is preferable to point the edge of the chip with a pointing device while viewing the chip on the display.

  The step (i) includes: (i1) imaging each of the chips; (i2) comparing the captured image with a standard image, and comparing the captured image from the marking reference point of the standard image. Measuring the x, y deviation and the tilt angle of the marking reference point.

  According to the correction method of the laser marking system of the present invention, the marking quality in each cell and the alignment error of each chip can be measured, and the marking quality can be improved by adjusting the galvano scanner so as to correct these errors.

  Hereinafter, a marking correction method of a laser marking system according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 5 is a schematic view showing a configuration of a laser marking system to which a marking correction method according to a preferred embodiment of the present invention is applied. Is omitted.

  The laser marking system 160 includes a tray supply magazine 120 on which a plurality of trays 110 are stacked, a loader 130 that pulls out one tray 110 from the magazine 120 and aligns it with a horizontal transfer table 122, and trays on the horizontal transfer table 122. Step motor 150 for transferring 110 in one direction, laser marker 160 for marking characters on each chip in a cell of tray 110 transferred to the lower side thereof, and a post vision camera for imaging the marking on the marked tray 110 170 and an unloader 180 for unloading the marked tray 110 to the tray collection magazine 190. The laser marking system is provided with a control unit 100 for controlling the loader 130, the pre-vision camera 140, the step motor 150, the laser marker 160, the post vision camera 170, and the unloader 180.

  The post vision camera 170 is a CCD (Charge Coupled Device) camera. The CCD is a photoelectric conversion sensor that converts light into an electrical signal. The intensity of light entering a lens (not shown) at the front end of the camera 170 is first recorded on the CCD. The image light captured at this time is separated into different colors by the RGB color filter attached to the CCD. The separated colors are converted into electrical signals by hundreds of thousands of photosensors (corresponding to pixels) constituting the CCD. An analog signal output from the CCD is converted into a digital signal of 0 and 1, and a video signal is generated and output. The post vision camera 170 receives light from the tray 110 and generates an electrical video signal. A video signal captured by the camera is transmitted to the control unit 100.

  FIG. 6 is a drawing schematically showing the configuration of the laser marker of FIG.

  Referring to FIG. 6, the laser marker 160 receives light from a laser oscillator 161, a galvano scanner 163, an F-theta lens 164, and a plurality of chips c in the tray 110, which is a marking object, and generates an electrical video signal. And a controller (not shown) for adjusting the x mirror 163a and the y mirror 163b of the galvano scanner 163 according to the chip position information from the vision camera 165. Is provided.

  The galvano scanner 163 includes an x mirror 163a and a y mirror 163b and motors (not shown) for driving the mirrors 163a and 163b, respectively, and adjusts the positions of these mirrors to scan a laser beam in a predetermined area in the XY direction. Let

  The F-theta lens 164 allows the incident laser beam to form a focal point of the same size with respect to the entire marking object 110.

  The vision camera 165 uses the same CCD camera as the post vision camera 170, and preferably one or a plurality are arranged so as to image the entire surface of the tray 110 in the direction perpendicular to the transfer direction of the tray 110. Is desirable. Thus, the number of vision cameras used is determined by the size of the tray and the field of view of the camera. For example, the length of the tray in the longitudinal direction (the length in the tray transfer direction) is 320 mm, the length of the tray in the longitudinal direction and the vertical direction is 150 mm, and the vision camera has a field of view of 100 × 100 mm. When two trays are arranged in the direction perpendicular to the tray transfer direction, the tray 110 can be transferred four times to the step motor 150 and the entire surface of the tray can be imaged with a vision camera. If four vision cameras are arranged 2 × 2 in the direction perpendicular to the tray transfer direction, the tray 110 can be transferred twice to the step motor 150 and the entire surface of the tray can be imaged by the vision camera.

  On the other hand, it is desirable that the post vision camera 170 observes the marking state while moving the tray 110 arranged and transferred in the direction perpendicular to the transfer direction.

  The correction method of the laser marking system of the present invention using the laser marking system will be described in detail.

  7A and 7B are flowcharts illustrating a marking correction method of a laser marking system according to a preferred embodiment of the present invention.

  First, it is checked whether or not the marking error in each cell is to be calculated (step 10).

  If it is determined in the tenth stage that the marking error is calculated, when using a plurality of vision cameras 165, for example, four vision cameras 165, a chip to be observed by each vision camera 165 is assigned (step 11).

  FIG. 8 is a flowchart for explaining an example 11A of the eleventh stage shown in FIG. 7A.

  Referring to FIG. 8, first, a marking sheet (not shown) is attached to the surface of the tray 110 or a plate (not shown) having the same shape as the tray, and is disposed below the vision camera 165 (step 30). . As the marking paper, it is desirable to use a paper in which black is printed on a white paper, and to arrange the marking paper so that the surface of the marking paper is located at the focal length of the F-theta lens 164.

  Next, one point, for example, the center point of each cell is marked with the laser marker 160 (step 32).

  Then, the vision camera 165 is searched for the central point by the vision camera 165 and the respective cells are observed (step 34).

  After the eleventh step, the coordinate system of each vision camera 165 and the coordinate system of the laser marker 160 are matched (step 12). This is a process in which the coordinates of the coordinates viewed by the vision camera 165 and the coordinates of the coordinates viewed by the laser marker 160 are different from each other.

  FIG. 9 is a flowchart for explaining an embodiment 12A of the twelfth stage shown in FIG. 7A.

  Referring to FIG. 9, first, the laser marker 160 marks a square edge of a region corresponding to a cell with reference to the center point in the thirty-second step (step 42). At this time, the edge point is marked by the coordinate system of the laser marker 160.

  Next, the position of the outline point of the selected cell is detected by the coordinate system of the vision camera 165 and compared with the coordinate system of the laser marker 160 in the forty-second stage (step 44).

  After the twelfth stage, after marking a predetermined first symbol S1 at a position corresponding to each chip, a pointing device (not shown) is observed while observing the first symbol S1 selected by the vision camera 165 on the display (not shown). The edge of the first symbol S1 is pointed at a reference point P1 (not shown) (see FIG. 10). That is, the reference point P1 is taught to the vision camera 165 (13th stage).

  Next, the first symbol S1 and the reference point P1 are searched while observing each cell with the vision camera 165, and the second symbol S2 is marked using the reference point P1 as a reference (step 14).

  The tray 110 or plate after the marking process is transferred to a position below the post vision camera 170 and is preferably observed one cell at a time by the post vision camera 170 moving in the direction perpendicular to the tray transfer direction. The operator points one point P2 of the second symbol S2 with a pointing device while teaching one of the chips on the display, and teaches the comparison point P2 to the post vision camera 170 (step 15).

  Next, after detecting the reference point P1 and the marking reference point P2 of each cell with the post vision camera 170 and measuring the position of the comparison point P2 from the reference point P1, the marking error is calculated from the deviation between two predetermined points. Then, it is stored in the memory (step 16). For the marking error stored in the memory, the marking error is corrected by correcting the adjustment values of the x mirror 163a and the y mirror 163b of the galvano scanner 163.

  The calculation process of the marking error is applicable when the chips are arranged uniformly in each cell of the tray 110 or when the chips are formed on the strip, but when the chips move in the tray 110. Again, the alignment error of each chip must be measured and corrected.

  Next, the tray 110 on which the chips are loaded in the cell is arranged at the same position as the 30th stage (17th stage).

  Next, it is determined whether a new marking reference point has to be designated (step 18). On the other hand, when the marking error in each cell previously stored in the memory in the tenth step is used, the eighteenth step is performed.

  If it is determined in the eighteenth step that a new marking reference point is designated, the point selected by the vision camera 165 is viewed on the display, and one point of the chip, for example, one edge point P3 is pointed with a pointing device. Teaching the vision camera 165 as the marking reference point P3 (step 19) (see FIG. 11).

  Next, each chip is imaged by the vision camera 165 and the alignment error of each chip is calculated (step 20). If it is determined in the eighteenth step that the pre-stored marking reference point P3 is used, the twentieth step is performed.

  FIG. 12 is a flowchart for explaining an embodiment 20A of the twentieth stage shown in FIG. 7B.

  Referring to FIG. 12, first, the position of each chip is imaged by the vision camera 165 (step 50).

  Next, the standard image of the chip (displayed with a dotted line in FIG. 12) is compared with the measured image of each chip (displayed with a solid line in FIG. 12), and the standard image corresponding to the marking reference point P3 from the point P0 is obtained. The x and y deviations dx and dy of the marking reference point P3 and the measured tip inclination angle θ are measured (step 52).

  After the twentieth stage, marking is performed by correcting the marking error of the cell calculated in the thirty-second stage based on the marking reference point P3 of each chip and the alignment error of each chip calculated in the twenty-second stage (21st stage). Stage). That is, in consideration of the error, the x mirror 163a and the y mirror 163b of the galvano scanner 163 are adjusted to mark each chip.

  In the above embodiment, the method for marking each chip in the cell of the tray has been described. However, when marking each chip formed on the strip, the method can be applied to a method for detecting a marking error of each chip and correcting the marking. It is.

  In the above embodiment, the marking correction method in the marking system using a plurality of vision cameras has been described. However, the present invention is also applicable to the case where one width of the tray or strip is observed with one vision camera.

  The present invention has been described with reference to the embodiments with reference to the drawings. However, the embodiments are illustrative only, and various modifications and equivalent other embodiments may be made by those skilled in the art. I understand. Therefore, the true technical protection scope of the present invention must be determined by the claims.

1 is a schematic plan view of a general lead frame strip. FIG. 1 is a schematic view of a general laser marking system. It is drawing which shows the structure of the laser marker of FIG. 2 roughly. 2 is a diagram illustrating a general tray and a chip located therein. 1 is a diagram schematically illustrating a configuration of a laser marking system to which a marking correction method according to a preferred embodiment of the present invention is applied. 6 is a drawing schematically showing a configuration of a laser marker in FIG. 5. 5 is a flowchart illustrating a correction method of a laser marking system according to a preferred embodiment of the present invention. 5 is a flowchart illustrating a correction method of a laser marking system according to a preferred embodiment of the present invention. FIG. 7B is a flowchart illustrating an example of an eleventh stage shown in FIG. 7A. It is a flowchart explaining one Example of the 12th step shown by FIG. 7A. It is drawing explaining measuring the marking error in each cell. 6 is a diagram illustrating measuring a chip alignment error. It is a flowchart explaining one Example of the 20th step shown by FIG. 7B.

Explanation of symbols

10 strip 12 chip 14 recognition tag 20,120 supply magazine 22,122 horizontal transfer table 30,130 loader 40 prevision camera 50,150 step motor 60,160 laser marker 61,161 laser oscillator 63,163 galvano scanner 63a, 163a x mirror 63b, 163b y mirror 64, 164 F-theta lens 100 control unit 110 tray 165 vision camera 167 light

Claims (10)

In a marking correction method of a laser marking system, comprising a laser marker for marking while observing a chip loaded in each cell of a tray with at least one vision camera, and a post vision camera for detecting a marked error,
(A) assigning an observation target chip to each vision camera;
(B) matching the coordinates of each vision camera and laser marker;
(C) marking each chip or a predetermined first symbol at a position corresponding to each chip, observing the first symbol selected by the vision camera, and teaching one point of the symbol as a reference point;
(D) observing the first symbol and the reference point of the chip with the vision camera and marking the second symbol on each chip based on the reference point;
(E) observing a second symbol on the selected chip and teaching a comparison point of the symbol;
And (f) detecting a marking error in each cell by detecting the position of the comparison point from the reference point on each chip, and a marking correction method for a laser marking system. The step (a) includes:
(A1) a step of attaching a marking sheet to the surface of the tray or a plate having the same shape as the tray and disposing it below a plurality of vision cameras;
(A2) marking one point in each cell with the laser marker;
The method according to claim 1, further comprising: (a3) assigning a vision camera that looks for the point with the vision camera and observes each cell.   The marking correction method of the laser marking system according to claim 2, wherein the point is a center point of the cell. In step (b),
(B1) marking an outer edge point of the cell region with the laser marker as a reference with respect to the center point;
The laser marking according to claim 3, further comprising: (b2) detecting the position of the edge point with the vision camera to match the coordinate system of the laser marker with the coordinate system of the vision camera. System marking correction method.   2. The method of claim 1, wherein the step (c) includes pointing an edge of the first symbol with a pointing device while viewing the first symbol on a display.   The laser marking system according to claim 1, wherein in the step (e), an edge of the second symbol is pointed with a pointing device while the second symbol is viewed on a display connected to the post vision camera. Marking correction method. (G) arranging a tray loaded with chips to be marked below the vision camera;
(H) observing a chip selected by the vision camera and teaching one point of the chip as a marking reference point;
(I) imaging each chip with the vision camera and calculating the alignment error of each chip;
5. The marking correction method for a laser marking system according to claim 4, further comprising: (j) marking by correcting the marking error and the alignment error with reference to the marking reference point of each chip. .   8. The marking correction method for a laser marking system according to claim 7, wherein in the step (g), the tray is disposed at the position of the plate in the step (a1).   8. The marking correction method for a laser marking system according to claim 7, wherein, in the step (h), the edge of the chip is pointed with a pointing device while the chip is viewed on a display. In step (i),
(I1) imaging each of the chips;
(I2) comparing the captured image with a standard image and measuring the x, y deviation and tilt angle of the marking reference point of the captured image from the marking reference point of the standard image. The marking correction method for a laser marking system according to claim 7.

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