The present invention relates to a catting blade detecting mechanism for use in a cutting apparatus.
Workplaces with a plurality of devices such as Integrated circuits (ICs), large-scale integration (LSI) circuits, etc. formed on their face sides are ground on their reverse sides to a predetermined thickness, and then divided toy a processing apparatus such as a dicing apparatus or the like into individual devices, which will be used in electronic apparatuses such as mobile phones, personal computers, etc. Devices on workplaces are packaged by a technology called quad flat nonleaded (QFN) packaging, for example. Packaged substrates fabricated by the QFN packaging are divided into individual devices by a rotating disk-shaped cutting blade in a dicing step that follows a packaging resin encapsulating step,
When a cutting blade cuts packaged substrates, the cutting blade is unevenly worn with its tip end worn irregularly. As the uneven wear develops on the cutting blade, the unevenly worn tip end of the cutting blade leaves a flaring shaped mark on package side surfaces at a certain stage during the process of dividing packaged substrates, possibly producing oversized defective packages. Therefore, it is necessary to perform dicing on packaged substrates with a cutting blade while the operator is confirming the state of wear on the tip end of the cutting blade. Even if a cutting blade has not been unevenly worn to the extent that it brings out defective products, since cutting blades gradually lose their sharpness by repeating cutting sessions, it is desirable for the operator to recognise a proper timing to replace cutting blades that have become blunt due to wear.
There has been proposed a cutting apparatus having a test material to be cut by a cutting blade for presenting its cut state for an examination to see how much the cutting blade has been worn, and observing means for observing the cutting quality of the cutting blade that is transferred to the test material, so that the cutting blade can be checked for its wear and it can be decided whether the cutting blade should be replaced or not (see, for example, Japanese Patent Laid-open No. 2007-296604).
Existing cutting blade detecting mechanisms are problematic in that they need to temporarily stop a product processing operation in order to examine cutting blades for their wear, resulting in product processing down time.
It is therefore an object of the present invention to provide a cutting blade detecting mechanism for cutting apparatus which is capable of detecting the state of a cutting blade quickly and highly accurately compared to conventional cutting blade detecting mechanisms.
In accordance with an aspect of the present invention, there is provided a cutting blade detecting mechanism for use in a cutting apparatus including a chuck table for holding a workpiece thereon and cutting means Including a cutting blade having an annular cutting edge for cutting the workpiece held on the chuck table while the workpiece is being cutting-fed in an X-axis direction, the cutting blade detecting mechanism having blade detecting means for detecting the state of the cutting edge of the cutting blade. The blade detecting means includes an image capturing milt configured to capture an image of an outer: periphery including an outer periphery end of the cutting edge in the X-axis direction, a light emitter disposed in a position opposite the image capturing unit and facing the cutting edge, and a decision unit configured to determine the state of the shape of a tip end of the cutting edge from the image of the outer periphery of the cutting edge which has been captured by the image capturing unit.
In the cutting blade detecting mechanism according to the present invention, the image capturing unit captures an image of the outer periphery including the outer periphery end of the cutting edge in the X-axis direction which is a cutting feed direction, and the decision unit determines the state of the shape of the tip end of the cutting edge from the image of the outer periphery of the cutting edge. The shape of the tip end of the cutting edge can be detected highly accurately while the cutting apparatus is suffering minimum down time.
The cutting blade detecting mechanism according to the present invention is thus capable of detecting the state of the cutting blade quickly and highly accurately compared to conventional cutting blade detecting mechanisms.
The above and other objects, features and advantages of the present invention and the manner of realizing them will become more apparent, and the invention itself will best be understood from a study of the following description and appended claim with reference to the attached drawings showing some preferred embodiments of the invention.
Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
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The chuck table 20 that holds the workpiece W thereon is mounted on the X-axis table 24 for rotation about a Z axis that is shown as a vertical axis perpendicular to the X-axis directions in
The column 28 supports thereon indexing feed means 30 for indexing-feeding the cutting means 10 in Y-axis directions, which, are perpendicular to the X-axis directions and the 2-axis directions, and a pair of incising feed means 31 for incising-feeding the cutting means 10 in the 2-axis directions. The indexing feed means 30 includes a pair of parallel guide rails 32 disposed on a front surface of the column 28 and extending in the Y-axis directions and a pair of Y-axis tables 33 slidably mounted on the guide rails 32. Each piece of the incising feed means 31 includes a pair of parallel guide rails 34 disposed on one of the Y-axis tables 33 and extending in the Z-axis directions and a Z-axis table 35 slidably mounted on the guide rails 34.
The cutting means 10 are mounted on the lower ends of the Z-axis tables 35. The Y-axis tables 33 and the Z-axis tables 35 have respective, nut units, not shown, disposed on reverse sides thereof and threaded over ball screws 36 and 37 disposed between the guide rails 32 and 34. The ball screws 36 on the Y-axis tables 33 and the ball screws 37 on the Z-axis tables 35 have ends coupled to electric drive motors 38 and 39. When the electric drive motors 38 are energized to rotate the ball screws 36 about their own axes, the Y-axis tables 33 and hence the cutting means 10 are indexing-fed in the Y-axis directions along the guide rails 32. When the electric drive motors 39 are energized to rotate the ball screws 37 about their own axes, the Z-axis tables 35 and hence the cutting means 10 are incising-fed in the Z-axis directions along the guide rails 34.
The cutting means 10 are paired in respective positions spaced from each other along the Y-axis directions. Since the cutting means 10 are essentially identical in structure to each other, one of the cutting means 10 will be described below. The present invention is also applicable to a cutting apparatus which includes a single piece of cutting means 10.
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The cutting means 10 also includes a box-shaped blade cover 15 disposed partly around the cutting blade 11 to cover the same, except a lower portion of the cutting blade 11 that projects downwardly. A pair of substantially L-shaped side nozzles 16 extend from one side of the blade cover 15 in the X-axis directions and are disposed one on each side of the cutting blade 11. The side nozzles 16 eject cleaning water sideways toward the cutting blade 11 in the Y-axis directions. A shower nozzle 17 and a pair of front nozzles 18 are disposed on the other side of the blade cover 15 in the X-axis directions. The shower nozzle 17 ejects cleaning water toward the cutting blade 11 in one of the X-axis directions. The front nozzles 18 eject cleaning water toward the workpiece W (see
The cutting apparatus 1 Includes control means 40 (see
For cutting the workpiece W on the cutting apparatus 1 which is constructed as described above, the workpiece W that is held on the chuck table 20 is loaded into a processing area where the workpiece W can be processed by the cutting means 10. In
When the cutting of the workpiece W along the projected dicing line is over, the indexing feed means 30 is actuated to move the cutting means 10 in one of the Y-axis directions until the cutting edge 14 of the cutting blade 11 over a next uncut projected dicing line in positional alignment therewith. Then, the cutting means 10 cuts the workpiece W along the projected dicing line in the same manner as described above. When the workpiece W has been cut along all the projected dicing lines that are arrayed in the Y-axis directions, the chuck table 20 is turned 90 degrees about the 2 axis along the 2-axis directions, orienting uncut projected dicing lines on the workpiece W parallel to the Y-axis directions. Then, the cutting means 10 cuts the workpiece W along all the uncut projected dicing lines that are arrayed in the Y-axis directions. The workpiece W has now been cut along all the projected dicing lines in the grid pattern, and divided into individual devices demarcated by the projected dicing lines. The workpiece W thus cut is unloaded from the processing area, whereupon the cutting process of the cutting apparatus 1 is finished.
When the cutting process described above is repeated, the cutting edge 14 of the cutting blade 11 is worn. The cutting apparatus 1 includes a cutting blade detecting mechanism having blade detecting means for detecting the state of the cutting edge 14. Details of cutting blade detecting mechanisms according to different embodiments of the present invention will be described below with reference to
The image capturing unit 51 includes an image capturing optical system (lens system) 53 capable of focusing an optical image of a subject and an image capturing element 54 for detecting the optical image focused by the image capturing optical system 53. The image capturing element 54 generates an image signal from the optical image produced by the image capturing optical system 53 by way of photoelectric conversion and sends the image signal to the control means 40. The control means 40 includes, in addition to the decision unit 41, an image processor 42 for processing the image signal sent from the image capturing element 54 to generate image data of the subject, and a memory 43 for storing the image data from the image processor 42.
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Providing the cutting edge 14 of the cutting blade 11 is observed from the image capturing unit 51 along the X-axis directions, the cutting edge 14 is positioned in front and the light emitter 52 is positioned behind the cutting edge 14 in the observational viewing field of the image capturing unit 51. When the light emitter 52 is energized, it illuminates the observational viewing field, making it possible for the image capturing unit 51 to capture an image of the outer periphery of the cutting edge 14. The state of the cutting edge 14 is detected on the basis of the captured image.
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The image capturing unit 51 and the light emitter 52 are provided in respective positions where they do not obstruct water ejected from the side nozzles 16, the shower nozzle 17, and the front nozzles 18, and hence do not adversely affect the Cutting process performed by the cutting means 10.
In a stage prior to detecting the state of the cutting edge 14 of the cutting blade 11, the image capturing unit 51 captures an image of the shape of the outer periphery of the cutting edge 14 which is in a good state not yet worn, and stores its image data in the memory 43. The image data thus stored represents a reference image to be referred to later. For example, the state of the cutting edge 14 immediately after its shape has been corrected by truing (making it into a true circle) and it has been unclogged by dressing may be used as a timing to capture a reference image.
For inspecting the state of the cutting edge 14 after the cutting blade 11 has been in service for some time, the image capturing unit 51 captures an image of the shape of the outer periphery of the cutting edge 14. It is desirable that image capturing conditions at this time should match those for acquiring a reference image. The decision unit 41 then compares the image of the outer periphery of the cutting edge 14 that has been in service and the image of the outer periphery of the cutting edge 14 in a good state that is stored in the memory 43 with each other, and decides whether the cutting edge 14 is still kept in a good state or not.
The image capturing unit 51 captures images of the outer periphery of the cutting edge 14 and the decision unit 41 makes a decision at a designated frequency while the cutting apparatus 1 is operating in a fully automatic mode. Specifically, the designated frequency may cover times including a time after the cutting blade 11 has been set up and its original position has been established.
While the cutting apparatus 1 is operating in the fully automatic mode, the image capturing unit 51 captures images of the outer periphery of the cutting edge 14 at the time the spindle 13 is rotating. In order to capture clear images of the cutting edge 14 along its full circumference even when the spindle 13 is rotating, appropriate timings are established for the light emitter 52 to emit light and for the image capturing unit 51 to capture images. Specifically, in a single image capturing session, the image capturing unit 51 can capture an image of a partial area of the cutting edge 14 in the direction in which the cutting blade 11 rotates. The number of times that the image capturing unit 51 has to capture images in order to cover the entire circumference of the cutting edge 14 and the timings at which the image capturing unit 51 has to capture such images can be calculated on the basis of conditions which include the number of revolutions of the cutting blade 11 per unit time, the circumferential length of the cutting edge 14 in the direction in which the cutting blade 11 rotates, and an angular range of the cutting edge 14 whose image can be captured by the image capturing unit 51 per image capturing session. The light emitter 52 may emit light intermittently, i.e., may emit blinking light, in synchronism with the timings at which the image capturing unit 51 captures images, or may emit light at all times and a shutter in the image, capturing unit 51 may be selectively opened and closed to control the light applied from the light emitter 52 to the image capturing unit 51.
In order to capture clear images of the cutting edge 14 along its full circumference when the spindle 13 is in rotation, the image processor 42 binarizes images captured by the image capturing unit 51. The binarized images provide a sharp contrast between image areas where light emitted from the light emitter 52 has been blocked by the cutting blade 11 and image areas where light emitted from the light emitter 52 has reached the Image capturing unit 51 without being obstructed by the cutting blade 11, so that the decision unit 41 can decide how much the cutting edge 14 has been worn with increased accuracy and at an increased processing speed.
The decision unit 41 detects the current state of the cutting edge 14 from the comparison of the images shown in
If the decision unit 41 decides that the cutting edge 14 is not in a good state because of uneven wear or the like, then the control means 40 performs a predetermined process. For example, the control means 40 indicates an error through indicating means 45 (see
The accuracy with which the state of the cutting edge 14 is detected is affected by the quality of images acquired by the image capturing unit 51. In order for the decision unit 41 to clearly recognize the state of the cutting edge 14 based on images acquired by the image capturing unit 51, the images are required to be clear focused images. The image capturing unit 51 can acquire a clear focused image in one image capturing session only when it is captured within the depth of field of the image capturing optical system 53 in the X-axis directions. Any images captured outside of the depth of field of the image capturing optical system 53 are not clear. Therefore, the image capturing unit 51 has a focusing function for adjusting the focus of the image capturing optical system 53, and captures an image covering a subject, area in its entirety while adjusting the focus in the X-axis directions, or stated otherwise, captures an image that is fully focused in its entirety in the X-axis directions, so that the state of the cutting edge 14 can be recognized highly accurately in a wide range in the X-axis directions based on the image. As can be understood from
Providing the images of the outer periphery of the cutting edge 14 are of a higher magnification, minute changes in the shape of the cutting edge 14 can be detected with higher accuracy. Therefore, the image capturing optical system 53 may have a function to change the image capturing magnification, i.e., a zooming function, so that the image capturing unit 51 can capture images at different magnifications. The higher the magnification is, the higher the accuracy with which to detect changes in the shape of the cutting edge 14 is, but the smaller the image capturing range becomes. If images of all partial areas of the cutting edge 14 are captured at a maximum magnification, then the period of time required to examine the cutting edge 14 tends to be long. In view of this shortcoming, the control means 40 may control the image capturing unit 51 to capture images of the cutting edge 14 at a lower magnification to grasp the entire state of the outer periphery of the cutting edge 14, and then capture images of particular areas of the outer periphery end 14a of the cutting edge 14 at a higher magnification to detect slight changes in the worn state of the cutting edge 14.
The image capturing unit 51 may capture moving images of the cutting edge 14 as well as still images thereof. When the image capturing unit 51 captures moving images of the cutting edge 14 while the cutting blade 11 is rotating, the control means 40 can detect, how much the cutting edge 14 fluctuates in the Y-axis directions and the Z-axis directions in addition to changes in the shape of the cutting edge 14 as described above.
Inasmuch as the cutting blade detecting mechanism detects the state of the cutting edge 14 through an optical observation of the cutting edge 14 without mechanical contact therewith, it can detect the state of the cutting edge 14 efficiently while the cutting means 10 is in operation without stopping a product processing operation of the cutting apparatus 1, i.e., without stopping the fully automatic mode of operation of the cutting apparatus 1. The cutting blade detecting mechanism can detect the state of the cutting edge 14 at any desired timings that are selected. After the cutting blade 11 has been set up, as described above, the state of the cutting edge 14 can be detected efficiently without wasting time.
In the first and second embodiments described above, images of the cutting edge 14 of the cutting blade 11 are captured in the X-axis directions along which the chuck table 20 is cutting-fed by the cutting feed means 22. Consequently, the shape of both sides of the outer cutting edge 14 in the Y-axis directions, in particular, of the periphery end 14a can be detected highly accurately. If images of the outer periphery of the cutting edge 14 are captured in the Y-axis directions unlike images captured in the embodiments of the present invention, then though an amount of wear on the cutting blade 11 in the Z-axis directions, i.e., the diametrical directions of the cutting blade 11, can be detected from the captured images, irregular wear on the cutting blade 11 in the Y-axis directions, i.e., the widthwise directions of the cutting blade 11, is difficult to recognize from the captured images. According to the embodiments of the present invention, it is possible to determine the state of wear on both sides of the cutting edge 14 in the Y-axis directions in addition to the state of wear on the cutting edge 14 in the Z-axis directions, as shown in
In the above embodiments, the cutting blade 11 is illustrated as a hub blade in which the cutting edge 14 is fixed to the hub base 11a. However, the cutting blade 11 is not limited to such a hub blade, but may be a hubless washer blade. The chuck table 20 is not limited to a suction-chuck table, but may be an electrostatic-chuck table. The cutting process performed by the cutting blade 11 is not limited to a process of dividing a workpiece along projected dicing lines thereon, but may be a process of trimming a workpiece edge by cutting it off.
Workpieces that can be processed by the cutting apparatus 1 include semiconductor device wafers, optical device wafers, packaged substrates, semiconductor substrates, inorganic material substrates, oxide wafers, raw ceramics wafers, piezoelectric substrates, and various other workpieces, for example. Semiconductor device wafers may be silicon wafers or compound semiconductor wafers with devices formed thereon. Optical device wafers may be sapphire wafers or silicon carbide wafers with devices formed thereon. Packaged substrates may be chip size package (CSP) substrates. Semiconductor substrates may be made of silicon, gallium arsenide, and so on. Inorganic material substrates may be made of sapphire, ceramics, glass, and so on. Oxide wafers may be lithium tantalate wafers or lithium niobate wafers with or without devices formed thereon.
While the embodiments of the present Invention have been described, the above embodiments and modifications may be combined wholly or partly as other embodiments of the present invention.
The present invention is not limited to the embodiments and modifications described above, but many changes, replacements, and modifications may be made without departing from the scope of the present invention. Furthermore, the present invention may be reduced to practice according to other techniques, processes, schemes, plans, or arrangements insofar as they are capable of implementing the principles of the present invention owing to technological advances or derivations. Therefore, the scope of the appended claim should be interpreted as covering all the embodiments falling within the range of the technical idea of the present invention.
As described above, the cutting blade detecting mechanism for the cutting apparatus according to the present, invention determines the state of the shape of the tip end of the cutting edge based on the images of the outer periphery of the cutting edge that have been captured in the cutting feed direction, thereby making it possible to examine the state of the cutting blade highly accurately and quickly, and contributing to an increase in the processing capability and productivity of the cutting apparatus.
The present invention is not limited to the details of the above described preferred embodiments. The scope of the invention is defined by the appended claim and all changes and modifications as fall within the equivalence of the scope of the claim are therefore to be embraced by the invention.
Number | Date | Country | Kind |
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2017-100492 | May 2017 | JP | national |