JPH02154432A - Pellet shape detection - Google Patents

Abstract

PURPOSE:To reduce detection time of a whole-corner shape by obtaining one received-image screen information for each pellet to recognize four whole-corner shapes of each pellet. CONSTITUTION:Regarding pellets 20 on all surfaces of a wafer 19, their position, presence/absence of improper mark, and presence/absence of corner cut are recognized and memorized. Namely, when recognizing a whole-corner shape of each pellet 20, the corner shape of corners of four pellets 20 which mutually face when receiving image of unit screen by the use of a camera 12 can be simultaneously recognized. To recognize each one corner shape, it is satisfactory to spend 1/4 screen information of one image-receiving screen information by the use of the camera 12. Thus, to recognize four whole-corner shapes of each pellet 20, it is satisfactory to obtain substantially one image-receiving screen information for each one pellet. Thus, detection time of a whole-corner shape can be substantially reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting the shape of pellets used in pellet honding.

[Prior Art] Generally, a pellet bonding apparatus picks up each pellet one by one from among a plurality of pellets formed on a grid by scribing on a wafer, and bonds and inks them onto a substrate such as a lead frame. At this time, the pellets to be bonded are required to be good quality pellets 1 to 1 having desired characteristics among the pellets on the wafer.

Therefore, each pellet on the wafer to be subjected to pellet bonding is processed on the wafer in a process before being carried into the pellet bonding inking apparatus, or in a process immediately before being carried into the pellet bonding inking apparatus and picked up. The position, presence or absence of defective marks, presence or absence of chipped corners, etc. are detected. The pellet pounding device will sequentially and selectively pick up desired pellets based on the detection results and bond and ink them as described above. Note that the defect mark is attached based on the measurement of the electrical characteristics of each pellet, and the chipping at the corner mainly occurs during the transportation process after the measurement.

However, when detecting the shape of the pellet mentioned above, in cases where the pellet is large and the area of the pellet is larger than the field of view of the camera, the following method is used: ■A method is adopted in which the shapes of the four corners of the pellet are sequentially detected over time.

That is, as shown in FIG.
- + g, capture one corner a of the pellet within the field of view of the camera, recognize the corner shape, and if it is determined that there is no chipping in this one corner, determine the center position of the pellet. This center position is drawn into the center of the field of view of the camera, and it is determined whether or not there is a defective mark in the center of the pellet. If there is no defective mark, the pellet is determined to be a good pellet. Subsequently, the pellet is moved to the corner C of the next pellet, and the same discrimination operation is repeated.

As shown in Fig. 5, the above detection method (2) involves scanning the wafer in the order p→q −+ r→5−+ t−+ u, and detecting four pellets within the field of view of the camera. Sp...
q, r, and s are taken in one after another, and their corner shapes are recognized each time they are taken in. When it is determined that there are no chips in all corners, the center position t of the pellet is calculated, and this center position t is The pellet is drawn into the center of the field of view of the camera, and it is determined whether or not there is a defective mark in the center of the pellet. If there is no defective mark, the pellet is determined to be good. Subsequently, the pellet is moved to the corner U of the next pellet, and the same determination operation is repeated.

[Problem to be solved by the invention] However, in the detection method (2) above, only one corner shape of each pellet is recognized, and the presence or absence of chipping in the other three corners is recognized. Therefore, the detection accuracy is poor.

In addition, in the detection method (■) above, all four corner shapes of each pellet are recognized, but the entire information of one image reception screen by the camera is used to recognize only one corner shape. Therefore, in order to recognize all the corner shapes of each pellet, substantially four pieces of image reception screen information are required for each pellet, and the detection time is long.

The present invention aims to detect all corner shapes of a pellet in a relatively short time.

Means for Solving the Problem] The present invention provides a pellet shape detection method for detecting the corner shape of each pellet among a plurality of pellets formed in a square shape on a wafer. When recognizing the shape, the corner shape of the mutually facing corners of a plurality of adjacent pellets is recognized, and when the corner shape of the final corner of each pellet is recognized, the corner shape of this final corner and the already recognized corner shape of the pellet in question are recognized. This completes recognition of all corner shapes including the corner shapes of other corners that have already been recognized.

[Function] In the present invention, when recognizing all the corner shapes of each pellet, when recognizing the unit of the detection system (when the unit screen is received by the camera), it is necessary to recognize the mutual relationship between a plurality of adjacent pellets, for example, four pellets. Simultaneously recognize the corner shapes of opposite corners. Therefore, in order to recognize each corner shape, it is sufficient to use, for example, the information of one image reception screen by the camera. That is, in order to recognize all four corner shapes of each pellet, it is sufficient to obtain substantially one image receiving screen information for each pellet, and the time for detecting all the corner shapes is substantially reduced. can.

[Example] Fig. 1 is a schematic diagram showing an example of a pellet shape detection device used for carrying out the present invention, Fig. 2 is a schematic diagram showing an example of the detection process, and Fig. 3 is a schematic diagram showing information on the image receiving screen of the camera. Pattern diagram,
FIG. 4 is a schematic diagram showing an example of a pickup device to which the present invention can be applied.

The pellet shape detection device 10 shown in FIG.
1, camera 12, image signal processing circuit 13, control circuit 14
, and a monitor television 15.

XY7--The crane 11 can be reciprocated in the X-axis direction and the Y-axis direction by motors 16 and 17, and supports the wafer mounting table 18. A wafer 19 is set on the wafer mounting table 18 via a wafer jig (not shown). On the wafer 19, a plurality of pellets 2o are spun fly pink and formed into a square shape, and are adhesively held on an adhesive sheet (not shown).

The camera 12 is disposed above the wafer 19, images each pellet 20, and transmits the imaging results to the image signal processing circuit 13.
Transfer to. 21 is the illuminator 1C.

The image signal processing circuit 13 performs signal processing on the imaging results of the camera 12 and transfers the signal processing results to the control circuit 14 and monitor television 15.

The control circuit 14 includes a detection operation program, an XY table control program, and a storage circuit for an image information memory. Thereby, the control circuit 14 determines the position of each pellet 20 based on the signal from the image signal processing circuit 13.
It stores image information such as the presence or absence of a defect mark attached to the approximate center of each defective pellet 20 and the presence or absence of chipping at a corner of each pellet 20, and controls the XY table 11.

The monitor television 15 displays image reception screen information of the camera 12 based on the signal from the image signal processing circuit 13.

Hereinafter, the shape detection operation of the beret according to this embodiment will be explained. In addition, in the following explanation, ■, ■, ■...
・ represents the position corresponding to the position ■, ■, ■, etc. in Figures 2 and 3, and the center position is denoted by ■, [phase], ■, etc.
・Place the respective pellets into Beretsu 1■, [phase], ■
It shall be expressed as follows.

The control circuit 14 of the pellet shape detection device 10 includes a camera 1
The XY table 11 is controlled so as to scan the wafer 19 in the order of ■, ■, ■, ■, .

Then, the corner shape of the upper left corner of the first pellet is recognized, and the information that the upper left corner of the pellet (2) exists is stored (see FIG. 3(A)).

■ At the same time, it recognizes the upper left corner of pellet 1-[phase], and at the same time recognizes the corner shape of the upper right corner of the adjacent pellet @ (see Figure 3 (B)). Recognize corner shapes. At this time, the scanning routes 1 to 1 to proceed next are also calculated from the shape information of the wafer 19 (diameter within the wafer outline and its center position), and the process proceeds to (3)
(See figure (C)).

At ■, the upper right corner of pellet O is recognized, and the process proceeds to ■.

■At the same time as recognizing the upper right corner of pellet 0,
The lower right corner of pellet ■ and the upper left corner of pellet O are also recognized (see Figure 3 (D)).

■ At the same time as recognizing the upper right corner of pellet O,
Upper left corner of pellet 0, lower right corner of pellet α,
and recognize the lower left corner of the pellet ■ (Fig. 3 (E)
)reference).

As soon as the bottom left corner of the pellet ■ is recognized, the pellet ■
You will be able to obtain information from four corners,
If the conditions of all corners or the external shape of the pellet are satisfied, move the field of view of the camera 12 to the center of the pellet ■,
A defect is detected, and if it is determined that there is no defective mark, this pellet (3) is stored as a good pellet.

Subsequently, proceeding to (2), corner shapes and defective marks of adjacent pellets are detected by the same method as described above.

In case (2), the lower right corner of the pellet has a missing number, so that pellet is recognized as a defective product (see FIG. 3(F)).

0, as shown in Figure 3 (G), even if the corner of the upper left pellet can be recognized, this pellet has already had the above-mentioned poor corner condition, so the recognition of the remaining corner shapes is canceled and the process is repeated as described above. Treated as defective, after O,
The process proceeds to the next pellet detection 0 without detecting whether or not a defective mark is attached to the center of this defective pellet.

Thereafter, the above-mentioned detection operation is repeated, and as a result, the positions of all the pellets 20 on the wafer 19, the presence or absence of defective marks, and the presence or absence of chipped corners are recognized and stored. This stored information is used as selection information for pellet pickup, etc. when this wafer 19 is provided to a Hondink device in a subsequent process.

Next, the operation of the above embodiment will be explained.

In the above embodiment, when recognizing all the corner shapes of each pellet 20, the corner shapes of the mutually facing corners of four adjacent pellets 20 can be recognized simultaneously when the unit screen is imaged by the camera 12. Therefore, in order to recognize each one corner shape, it is sufficient to use one image reception screen information of the rain surface by the camera 12. That is,
In order to recognize all four corner shapes of each pellet 20, it is sufficient to obtain substantially one image receiving screen information for each pellet, and the detection time for all the corner shapes can be substantially reduced.

In addition, in the above detection process, for pellets 20 that have already been recognized as having chips in some corners, recognition of the remaining corner shapes and detection of defective marks is canceled, and the field of view of the camera is immediately changed to the next one. By advancing to the imaging area, the total detection time for all pellets 20 on the wafer 19 can be shortened.

The pellet pick-up device 30 shown in FIG.
It picks up each piece one by one and transfers it to an intermediate positioning table or the like in order to place it on a board. 31 is X
Y table, 32 is a camera, 33 is an image signal processing circuit,
34 is a control circuit, 35 is a monitor television, 36 is a pickup collet, and 37 is a push-up needle.

The pellet pickup device 30, like the pellet shape detection device 10 described above, places the same wafer 19 as described above on a wafer mounting table 38 supported by an XY table 31. Further, the control circuit 34 controls the pellets 1 to the shape detection device 10.
Similarly to the control circuit 14, the position of each pellet 20 on the wafer 19 and the defective mark placed approximately at the center of the defective pellet 20 are determined based on the signal from the image signal processing circuit 33 based on the imaging result of the camera 32. In addition to storing image information such as the presence or absence of chips and the presence or absence of chipped corners of each pellet 20, the XY table 31 is controlled.

At this time, the pellet pickup device 30 detects the shape of each pellet 20 according to the present invention in the same manner as described above.
The center position of each pellet 20 imaged by the camera 32 is set above the push-up needle 37, and the pellets 20 determined to be good by the shape detection this time are immediately pushed up from above the adhesive sheet by the push-up needle 37, and the pick-up collet 36 Picked up by
This can be used for bonding onto a substrate.

In the implementation of the present invention, if the length β of each of the two sides constituting the corner of each pellet is at least % of the total length of one side of the pellet when the unit screen is imaged by the camera,
When recognizing the corner shape of the final corner, the entire contour shape including all corner shapes of the pellet can be recognized (
(See Figures 2 and 3 (E)).

[Effects of the Invention] As described above, according to the present invention, all corner shapes of a pellet can be detected in a relatively short time.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a pellet shape detection device used in carrying out the present invention, FIG. 2 is a schematic diagram showing an example of the detection process, and FIG. 3 is a schematic diagram showing information on the image receiving screen of the camera.
FIG. 4 is a schematic diagram showing an example of a pickup device to which the present invention can be applied, and FIG. 5 is a schematic diagram showing a conventional detection method. DESCRIPTION OF SYMBOLS 10... Pellet shape detection device, 11... XY table, 12... Camera, 13... Image signal processing circuit, 14... Control circuit, 19... Wafer, 20... Pellet... 30... Pellet pickup device, 31... XY
Table, 32... Camera, 33... Image signal processing circuit, 4... Control circuit. Figure 3 (B) (F) (D)

Claims (1)

[Claims] (1) In a pellet shape detection method that detects the corner shape of each pellet among a plurality of pellets formed in a square shape on a wafer, when recognizing the corner shape of a corner of each pellet, adjacent plural pellets are detected. The corner shapes of the corners facing each other are recognized, and when the corner shape of the final corner of each pellet is recognized, the corner shape of this final corner is combined with the corner shape of the other corners that have already been recognized of the pellet in question. A pellet shape detection method characterized by completely recognizing all corner shapes.