JP4237486B2 - Pellet pick-up method and pellet bonding apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pellet pick-up method and a pellet bonding apparatus.
[0002]
[Prior art]
One of the semiconductor manufacturing processes is a bonding process in which pellets are bonded to a lead frame or the like. In this process, a pellet bonding apparatus is used. This apparatus picks up pellets one by one from a plurality of pellets arranged in a lattice by scribing the wafer and bonds them onto a substrate such as a lead frame. At this time, the pellet to be bonded must be a non-defective pellet having desired characteristics.
[0003]
Therefore, in general, each pellet supplied to the pellet bonding apparatus has a defect mark, a corner defect, etc. in addition to the position on the wafer at the stage immediately before being loaded into the pellet bonding apparatus and picked up. It has come to be recognized. Based on these recognition results, the pellet bonding apparatus selectively picks up only non-defective pellets having desired characteristics one by one and bonds them as described above. In addition, a defect mark is attached | subjected to the surface of a pellet based on the electrical property measurement in a previous process.
[0004]
Here, a conventionally used pellet bonding apparatus will be described with reference to FIG.
[0005]
The pellet bonding apparatus 15 shown in FIG. 5 includes a wafer support device 16, a lead frame transport device 17, a bonding device 18, and a control device 19.
[0006]
The wafer support device 16 has a wafer holder 2 that supports a plurality of pellets arranged in a lattice pattern by scribing the wafer. The wafer holder 2 is disposed on the XY table 3 via a θ table (not shown), and the pellets 1 are sequentially positioned at the pickup position by the horizontal movement of the XY table 3. A camera 4 is installed above the pickup position. The camera 4 captures an image of one pellet positioned opposite to it. The image captured by the camera 4 is subjected to image processing by the image processing unit 5, and based on the processed image, the position of the pellet, the presence / absence of a defective mark on the surface of the pellet, and the presence / absence of a chipped corner of the pellet are detected. The detection result is transferred to the control unit 6 constituting the control device 19. On the basis of this detection result, the control unit 6 has no defect mark on the pellet surface and no chipped corners of the pellet, that is, when it is determined to be a non-defective pellet, the positional deviation between the detected pellet position and the reference position The XY table 3 and the θ table are corrected and moved by the amount, and the pellet 1 is accurately positioned at the pickup position. On the other hand, when it is determined that the pellet surface has a defective mark or a defective pellet in which chipping of a corner of the pellet is detected, the XY table 3 is moved by a specified amount (distance between pellets) to move the next pellet 1 To the pickup position.
[0007]
The lead frame transport device 17 has a feed mechanism (not shown), and the lead frame 10 is transported intermittently along the transport rail 9 by this feed mechanism.
[0008]
The bonding apparatus 18 has a bonding head 8 having a suction nozzle 7 at the tip. The bonding head 8 picks up the pellet 1 at the pickup position and bonds it to the island of the lead frame 10. Note that an adhesive is applied in advance to the bonding points in the lead frame 10, and the pellet 1 is bonded to the lead frame via the adhesive.
[0009]
The control unit 6 constituting the control device 19 controls the lead frame transport device 17 and the bonding device 18 constituting the pellet bonding apparatus, in addition to the above-described movement control of the XY table 3.
[0010]
The above-described pellet bonding apparatus 15 operates as follows.
[0011]
First, one pellet 1 on the wafer holder 2 is positioned at a pickup position, that is, a position facing the camera 4 by the movement of the XY table 3. Next, an image of the pellet 1 is captured by the camera 4. An image captured by the camera 4 is subjected to image processing by the image processing unit 5, and the position of the pellet, the presence / absence of a defective mark on the pellet surface, and the presence / absence of a chipped corner of the pellet are detected from the processed image. When the control unit 6 determines that the pellet is a non-defective pellet based on the detection signal from the image processing unit 5, the control unit 6 corrects the amount of displacement of the pellet 1 from the reference position and accurately positions it at the pickup position. Then, it is picked up by the suction nozzle 7 of the bonding head 8 and bonded to the lead frame 10 via an adhesive. After the pellet pick-up, the wafer holder 2 moves by one pitch, and the next pellet 1 is positioned at the bonding position.
[0012]
On the other hand, if it is determined as a defective pellet, the wafer holder 2 moves one pitch without performing the pickup operation, and the next pellet 1 is positioned at the pickup position.
[0013]
Thereafter, the pellet bonding apparatus 15 repeats the above-described operation.
[0014]
[Problems to be solved by the invention]
In the above-described pellet bonding apparatus, for each detection using the camera 4, an image of one pellet located at the pickup position is taken in, and the position is recognized and the quality is determined. For this reason, all the pellets 1 must be positioned once at the pickup position.
[0015]
By the way, considering the case where the pellet positioned at the pick-up position is determined to be a defective pellet, the time for positioning the pellet at the pick-up position is wasted time in terms of the operating rate of the bonding operation. That is, the bonding operation is stagnated during that time. This has been a bottleneck in improving the operating rate of the apparatus.
[0016]
The fact that all pellets 1 must be positioned once at the pickup position means that the XY table 3 on which the wafer holder 2 is mounted repeats acceleration / deceleration operations in small increments. The vibration generated in the XY table 3 due to the repeated acceleration / deceleration operation is transmitted to the bonding head 8 and the bonding accuracy is deteriorated.
[0017]
In addition, for the same reason, sliding parts such as a slide guide and a ball screw for driving that guide the movement in the horizontal direction used for the XY table 3 repeatedly move little by little. The worn grease was worn out, and the life of the sliding parts was shortened.
[0018]
Therefore, the present invention can improve the operation rate of the pellet pick-up operation, and when applied to the pellet bonding apparatus, leads to an improvement in the operation rate of the pellet bonding operation, and can improve the bonding accuracy, An object of the present invention is to provide a pellet pick-up method and a pellet bonding apparatus capable of extending the life of the apparatus.
[0019]
[Means for Solving the Problems]
The present invention relates to a pellet pick-up method for picking up non-defective pellets on a wafer one by one, and when the pellets in a certain row are positioned at the pick-up position, the pellets adjacent to this pellet and the pellets located in the next row The image is captured at the same time, and based on this captured image, the good / bad information of the pellet located in the next line is determined and stored together with the position information, and stored in the pellet pick-up operation of the next line. Based on the information, in the case of good information, the pellet is positioned at the pickup position, and in the case of defective information, the pellet is skipped without being positioned at the pickup position, and the pellet in the row adjacent to the pellet skipped by this skip is positioned at the pickup position. To make a pass / fail judgment It is characterized in.
[0020]
In the present invention, a plurality of pellets arranged in a lattice shape are imaged, the position of the pellet is determined based on the imaged information obtained by image recognition, the pellet is positioned at the pickup position, and the pellet is sequentially In the method of picking up one by one along a row, the pellet positioned at the pickup position and the pellet adjacent to the pellet at the pickup position and positioned in the next picked-up row are simultaneously image-recognized, and then the pellet Is moved along a line relative to the camera, and the image recognition is repeated sequentially along with the movement to determine the quality of the pellet. As a result, the quality information of the next picked-up pellet is sequentially sequentially line by line. The image-recognized pellets are picked up based on the accumulated pass / fail information of the pellets in units of one row. When positioned flop position, if the image recognized pellet is defective, the pellet is moved interlaced pickup position, pellet row adjacent to the pellets skipped by this movement is positioned at the pickup position It is characterized by determining pass / fail at that position .
[0021]
In this case, when the image-recognized pellet is positioned at the pick-up position based on the accumulated information, if the image-recognized pellet is a non-defective product, the pellet is moved to the pick-up position. It is preferable to recognize and position at the pickup position.
[0022]
The present invention also provides wafer support means for supporting a plurality of pellets arranged in a grid, image recognition means for recognizing an image after taking the pellets into the camera field of view, and picking up the pellets from the wafer support means. In the pellet bonding apparatus having bonding means for bonding on the object to be bonded and control means for controlling the movement of the wafer support means based on information from the image recognition means, the camera field of view is positioned at the pickup position. It is set so that the pellet adjacent to the pellet and the pellet at the pick-up position and located in the next picked-up row is displayed simultaneously, the image recognition means recognizes at least two pellets simultaneously, and the control means recognizes the pellet with the camera Move along the line relative to With the quality of the pellets is determined on the basis of information obtained by sequentially the image recognition, further control means have a sequential storage storing unit quality determination was quality information of pellets, wherein, the image pre If the pellet is defective, the pellet is moved over the pickup position, and the pellet in the row adjacent to the pellet skipped by this movement is positioned at the pickup position, and the quality is judged at that position. .
[0023]
In this case, said control means when said image recognized pellet For good so as to recognize the position by moving the pellet pick-up position preferred.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0025]
FIG. 1 is a schematic diagram for explaining a pellet pick-up operation to which the present invention is applied, FIG. 2 is a schematic diagram showing a camera field of view in pellet image recognition to which the present invention is applied, and FIG. 3 is an application of the present invention. FIG. 4 is a schematic diagram showing a schematic configuration of a pellet bonding apparatus to which the present invention is applied. In addition, the same code | symbol is attached | subjected to the same functional component as FIG. 5, and the detailed description is abbreviate | omitted.
[0026]
First, the apparatus configuration will be described with reference to FIG. The pellet bonding apparatus 50 shown in FIG. 4 is different from the pellet bonding apparatus 15 shown in FIG. 5 in that the control device 19 includes a storage unit 11 in addition to the control unit 6, and a plurality of cameras 60 are provided. The point is that a single pellet image can be taken in.
[0027]
Here, the image recognition operation | movement of the pellet 1 using the pellet bonding apparatus 50 shown in FIG. 4 is demonstrated.
[0028]
In FIG. 2, it is assumed that image recognition and pick-up operations proceed along the pick-up direction indicated by the arrows in FIG. The pellet 41 indicated by a broken line is a pellet that has been picked up, the pellet 21 is a pellet positioned at the pickup position, the pellet 51 is detected next, the pellet to be picked up, the pellet 31 is adjacent to the pellet 21 positioned at the pickup position, And the pellet located in the line picked up next is each shown.
[0029]
The camera field of view 12 is set so that at least the entire outer shape of the pellet 31 can be accommodated in addition to the image of the pellet 21 positioned at the pickup position. The image processing unit 5 performs image processing of the pellets 21 and the pellets 31 captured by the image capture once by the camera 4, and based on the processed images, the presence or absence of defective marks attached to the surface of each pellet, the pellets It is possible to detect good / bad information such as detection of the presence or absence of a corner chip using a conventionally known pattern recognition technique. The control unit 6 determines not only the position and quality of the pellet 21 but also the quality of the pellet 31 based on the detection result of the image processing unit 5, and the determination result is stored in the storage unit 11 together with the position information of the pellet. It can be memorized.
[0030]
From the above, the pick-up operation by the pellet bonding apparatus 50 is performed as follows.
[0031]
In FIG. 1, in the first row (the row located at the top in the figure), the pellets 1 are sequentially positioned at the pickup position, and the image of the positioned pellets 1 is recognized using the camera 60, and is determined to be non-defective. The bonding operation is sequentially performed on the object. The bonding operation for this row is not different from the conventional one. However, in the present embodiment, every time the pellet 1 is positioned at the pickup position, the control unit 6 also performs the pass / fail determination of the next pellet that is adjacent to the positioned pellet 1 and enters the camera field of view. The difference is that the determination result is sequentially stored in the storage unit 11 together with the position information of the pellet 1. In other words, by doing this, when the bonding operation of the currently picked-up row is completed, the pass / fail judgment result for the pellet 1 located in the next row is stored in one row unit together with the position information of the pellet. The data are sequentially stored and accumulated in the unit 11. This is shown in FIG.
[0032]
Therefore, the bonding operation for the next row (second stage in FIG. 1) is performed as follows.
[0033]
As described above, when the pickup target moves to the next row, the pass / fail judgment result of the pellet 1 located in that row has already been accumulated in the storage unit 11. Therefore, the control unit 6 calls the storage unit 11 to determine whether the pellet 1 positioned at the beginning of the next line is a non-defective product and performs the following control. In the case of FIG. 1, since the first pellet 1 in the next row has already been determined to be non-defective, this pellet 1 is positioned at the pickup position (a position corresponding to the position of the pellet 21 in FIG. 2) (A in the figure). Then, the camera 4 captures the image. In the image processing unit 5, the amount of displacement of the pellet 1 from the reference position is detected from the captured image, and the control unit 6 corrects and moves the XY table 3 and the θ table by the amount of displacement, and moves the pellet 1. Position it accurately at the pickup position. Thereafter, it is picked up by the suction nozzle 7 of the bonding head 8 and bonded to the lead frame 10. In addition, when the image of the pellet 1 is captured, an image of the pellet adjacent to the pellet 1 and located in the third row (third stage in FIG. 1) is also captured. Determination) is made and stored in the storage unit 11 together with the position information. In the case of FIG. 1, since the second-positioned pellet is already determined to be a non-defective pellet, when the pickup operation of the first pellet in the second stage is completed, the wafer stage 2 is moved in pitch, and the non-defective product is detected. Will be positioned at the pickup position. Similarly, the misalignment correction operation for the pellet, the quality determination of the pellet located in the third stage (in the case of FIG. 1, defective product determination), and storage in the storage unit 11 are performed in the same manner. In the case of FIG. 1, it is known at the time of pellet recognition in the first row that the following three pellets are defective (B in the figure). Therefore, the control unit 6 moves by four pitches at a time using this information. That is, pellets that are already known to be defective are skipped without stopping at the pickup position. Then, with respect to the non-defective product determination pellet newly positioned at the pickup position by this movement, as described above, the positional deviation correction operation and the non-defective determination of the pellet positioned in the third stage (in the case of FIG. 1, the non-defective product determination) The storage in the storage unit 11 is performed in the same manner.
[0034]
However, since an image of the pellet located in the third row adjacent to the pellet thus skipped cannot be obtained, the pickup row is changed to the third row for this pellet (C, D in the figure). When it moves, it is positioned once at the pickup position, and the quality is determined at that position as in the conventional case. After it is determined that the pellet is a non-defective pellet, a normal bonding operation is performed. When the image of the pellet is captured, an image of a pellet (not shown) adjacent to the pellet and located in the fourth row is also captured at the same time, and the quality is determined.
[0035]
FIG. 3 shows these in the flowchart.
[0036]
According to the present embodiment, the following effects can be obtained.
(1) Based on the image captured at one time, the good / bad information of the pellet positioned at the pickup position is detected, and the good / bad information of the pellet located in the next row is also detected and judged. Therefore, it is possible to make the pellet positioned at the pickup position as good as possible based on the information, so that the operation rate of the pickup operation can be improved. If applied to the pellet bonding apparatus, the stagnation time of the bonding head can be eliminated when the pellet is bonded to an object to be bonded such as a lead frame or a substrate, and the operation rate of the pellet bonding operation can be improved.
(2) For the same reason as in (1) , the repeated acceleration / deceleration operation by the XY table 3 is suppressed, whereby the occurrence of vibration is suppressed compared to the conventional case, and as a result, the bonding accuracy can be improved. .
(3) Further, for the same reason as in (1) , since repeated acceleration / deceleration operations are suppressed in small increments, a slide guide and a ball screw for driving that are used for the XY table 3 to guide the movement in the horizontal direction, etc. It is possible to prevent the life of the sliding component from being shortened due to the grease applied to the sliding portion of the sliding component, etc., and to prolong the device life.
[0037]
In general, the percentage of non-defective pellets in a wafer is about 60%, and the above-described effect becomes more significant as the non-defective ratio is lower.
[0038]
In the embodiment described above, images of two pellets in total, one pellet located adjacent to this pellet and the next row, together with the pellet image positioned at the pickup position, are captured at one time. Although the quality is judged as good or bad, it may be set as a field of view in which the pellet positioned at the pickup position, the pellet in the next next row, and further the pellet in the next next row can be taken in at a time. By widening the camera field of view in this way, the number of pellets that are not accumulated due to jumping of defective pellets can be reduced, so that it is possible to further reduce the waiting state in the pickup operation, that is, the generation of wasted time. It is possible to further improve the operating rate.
[0039]
Further, in the above embodiment, a case has been described in which one pellet is positioned in the camera field of view for one row, but the camera field of view includes adjacent pellets in the pickup direction including pellets in the next row to be picked up. For example, three pellets may be set. By setting in this way, the next row of pellets is recognized three times, so even if there are irregularities in the reflection of the pellets due to the illumination angle of illumination, etc., the same pellet is recognized three times, so the recognition accuracy Can be improved.
[0040]
Further, in the above-described embodiment, the image recognition and the pickup operation direction have been described in the horizontal direction in FIG. 2, but the vertical direction may be used in the same figure.
[0041]
In the above embodiment, the pellets are directly transported to the lead frame by the bonding head and bonded. However, the picked-up pellets are placed on a stage that is an intermediate stage, and the position is recognized using a camera or the like there. You may adapt to the system which corrects a position again and bonds to a lead frame. A type in which the push-up pin rises from under the wafer during the pickup operation may be used.
[0042]
In the above embodiment, the image of the next row adjacent to the pellet is taken together with the image of the pellet positioned at the pick-up position, and only the good / bad information is determined for the adjacent pellet. However, at the same time, the misregistration information is also detected and stored in the storage unit. When the pellet is positioned at the pickup position, the misregistration information is called from the storage unit, and a correction operation using the XY table is performed based on the information. You may do it.
[0043]
In the above embodiment, the camera is disposed so as to face the pellet positioned at the pickup position. However, the camera is disposed at a position facing the pellet positioned before the position positioned at the pickup position. An operation similar to that of the above-described embodiment may be performed based on the image and the image of the next-row pellet adjacent to the pellet.
[0044]
Further, in this specification, “adjacent” means being located in the vicinity, and is not necessarily limited to being located at the closest position.
[0045]
【The invention's effect】
As described above, according to the present invention, the operation rate of the pellet pick-up operation can be improved, and when applied to the pellet bonding apparatus, the operation rate of the pellet bonding operation is improved and the bonding accuracy is improved. In addition, the life of the apparatus can be extended.
[Brief description of the drawings]
FIG. 1 is a schematic diagram for explaining a pellet pick-up operation to which the present invention is applied.
FIG. 2 is a schematic diagram showing a camera field of view in image recognition of a pellet adapted to the present invention.
FIG. 3 is a flowchart of image recognition and pellet pick-up operations to which the present invention is applied.
FIG. 4 is a schematic diagram showing a schematic configuration of a pellet bonding apparatus to which the present invention is applied.
FIG. 5 is a schematic diagram showing a schematic configuration of a conventional pellet bonding apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pellet 2 Wafer holder 3 XY table 4 Camera 5 Image processing part 6 Control part 7 Suction nozzle 8 Bonding head 9 Transport rail 10 Lead frame 11 Storage part 12 Camera visual field 13 Non-defective pellet 14 Defective pellet 15 Pellet bonding apparatus 16 Wafer support apparatus 17 Lead frame transport device 18 Bonding device 19 Control device 21 Pellet 31 Pellet 41 Pellet 50 Pellet bonding device 51 Pellet 60 Camera

Claims (5)

In the pellet pick-up method for picking up good quality pellets one by one in the wafer, when the pellets in a row are positioned at the pick-up position, images of the pellets and the pellets located in the next row are simultaneously captured. Based on this captured image, the good / bad information of the pellet located in the next line is determined and stored together with the position information, and in the next line pellet pick-up operation, based on the stored information, In the case of good information, the pellet is positioned at the pickup position. In the case of defective information, the pellet is skipped without being positioned, and the pellet in the row adjacent to the pellet skipped by this skip is positioned at the pickup position and the pass / fail judgment is made at that position. Characterized by the fact that Pellet pickup how to. Image a plurality of pellets arranged in a grid, determine the position of the pellet based on the information obtained by image recognition and image recognition, position the pellet at the pickup position, and sequentially put the pellets one by one in a row In the method of picking up along, the pellet positioned at the pickup position and the pellet adjacent to the pellet at the pickup position and positioned in the next picked-up row are simultaneously image-recognized, and then the pellet is relative to the camera. The image recognition is sequentially repeated along with the movement, and the quality of the pellets is repeatedly judged. As a result, the quality information of the next picked-up pellets is sequentially accumulated and accumulated in units of one row. Based on the pass / fail information of the pellets per line, the image-recognized pellets are positioned at the pickup position. When the image-recognized pellet is defective, the pellet moves over the pickup position, and the pellet in the row adjacent to the pellet skipped by this movement is positioned at the pickup position. A method for picking up pellets, characterized in that Based on the accumulated information, when the image-recognized pellet is positioned at the pickup position, if the image-recognized pellet is a non-defective product, the pellet is moved to the pickup position to recognize the position. 3. The method for picking up pellets according to claim 2, wherein positioning is performed. Wafer support means for supporting a plurality of pellets arranged in a grid, image recognition means for recognizing an image after taking the pellets into the camera field of view, and picking up the pellets from the wafer support means, In a pellet bonding apparatus having bonding means for bonding to a wafer and control means for controlling movement of the wafer support means based on information from the image recognition means, the camera field of view is a pellet positioned at the pickup position and a pellet at the pickup position And the image recognition means recognizes at least two pellets simultaneously, and the control means rows the pellets relative to the camera. And move the image sequentially along with the movement. Based on the information obtained by recognition, the quality of the pellet is judged, and the control means further has a storage means for sequentially accumulating the quality information of the quality of the pellet. In this case, the pellet bonding apparatus is characterized in that the pellet is moved by jumping over the pickup position, and the pellet in the row adjacent to the pellet skipped by this movement is positioned at the pickup position and the quality is determined at that position. 5. The pellet bonding apparatus according to claim 4, wherein when the image-recognized pellet is a non-defective product, the control unit moves the pellet to a pickup position to recognize the position.

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