JPH0324783B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a pellet bonding apparatus for bonding small semiconductor pieces (pellets) on which circuit elements are formed to predetermined positions on a mounting substrate.

(Technical Background of the Invention) Generally, as one of the semiconductor manufacturing processes, pellets are sucked and held one by one from a pellet mounting table by a collector shaft having a suction portion at the tip, and the sucked and held pellets are transferred to a mounting board such as a lead frame. A pellet bonding operation is performed in which the pellets are bonded to predetermined positions.

By the way, in such pellet bonding work, as shown in FIG. 1, the pellet 2 bonded to the mounting board 1 has two opposing sides 2a,
2b is bonded at a predetermined position 3 so as to be parallel to two opposing sides 1a and 1b of the mounting board 1.

This means that if the pellet is as shown in Figure 1, that is, if the pads 4 on the pellet 2 are arranged at regular intervals around the pellet 2, the pellet 2 will be bonded accurately to the predetermined position 3 of the mounting board 1. As long as the wire bonding was carried out in the subsequent process, no particular problem occurred.

However, as is well known, depending on the type of pellet, the pads on the pellet may not only be arranged regularly as shown in Figure 1, but also as shown in Figure 2, where the pads 5 are scattered over the pellet 6. There are some that are set up. On the other hand, the external lead 7 to which such a pellet 6 is bonded is
Normally, the pellets 6 extend regularly toward a predetermined position 3 where they are bonded, and the two opposing sides 6a and 6b of the pellet 6 are connected to the two opposing sides of the mounting board 1 as in the conventional method. 1
When bonding is done in parallel to a and 1b, when connecting the pad 5 and the external lead 7 with a wire 8 consisting of the entire wire as shown in Fig. 2, the length of the connected wire 8 is If the wire length is long, there will be an underloop phenomenon (the wire hangs down), and because the height of the loops is uneven, the loops will fall over and shoot out during molding.

Therefore, bonding is performed by tilting the pellet at a certain angle with respect to the mounting substrate, and a bonding apparatus for this method is described, for example, in Japanese Patent Laid-Open No. 51-38970. According to this publication, a cam follower is attached to a rotating block that moves integrally with the collet shaft, and the cam follower moves along the plate cam to rotate the collet shaft, thereby keeping the collet attracted to the collet shaft at a constant position. The angle is rotated and bonding is performed in this state.

(Problems with the prior art) However, in the bonding device described in the same publication, only one type of rotation angle of the collet shaft can be obtained for one plate cam. It had to be reattached to the plate cam, and this replacement work took a lot of time. In addition, it was necessary to provide as many plate cams as the number of rotation angles required, which caused problems in terms of storage.

(Object of the Invention) The present invention has been made in order to eliminate the above-mentioned drawbacks, and it is an object of the present invention to provide a pellet bonding device that can bond pellets at various desired mounting angles by extremely simple adjustment. purpose.

(Structure of the Invention) In order to achieve the above object, the present invention includes the following:
A pellet bonding device comprising an arm that reciprocates between a pellet suction position and a pellet bonding position, and a collet shaft rotatably supported at one end of the arm about its axis. an elastic body provided between the collet shafts and urging the collet shaft to rotate in one direction; a stopper provided on the arm side to prevent the collet shaft from rotating in the one direction at a fixed position; It has an actuation plate that is rotated integrally and a cam follower attached to the actuation plate, and
The movement path of the arm includes a collet shaft rotating cam that operates on the cam follower to rotate the actuating plate in the other direction when the arm moves to the bonding position, and the cam follower contacts the cam. and adjusting means for moving and adjusting the cam in a direction that changes the rotation angle of the actuating plate.

(An embodiment of the invention) An embodiment of the invention will be described below with reference to the drawings.

FIG. 3 is a plan view of a rotating type pellet bonding apparatus to which the present invention is applied, and FIG. 4 is a partially cutaway right side view thereof.

In the figure, reference numeral 10 indicates a shaft 1 by a conventionally known means.
The arm 10 moves up and down in the order of arrows 12 to 17 along the arrows 12 to 17, and swings 90 degrees with respect to the shaft 11. At the tip of the arm 10, there is a collector shaft 19 having a pellet suction part 18 at one end, and a bush 20, A collet receiver 22 supported via 21 is fixed by bolts 23. The collect shaft 19 is provided with a through hole 24 on its central axis, and a pipe 25 connected to a vacuum pump (not shown) is connected to the upper end of the collect shaft 19 in the figure, so that the pellets can be placed on the pellet mounting table 26. When holding the pellets 27 by suction, the suction section 18 is evacuated. Further, a follower plate 29 having a U-shaped portion 28 provided so as to fit with a shaft 37, which will be described later, is fixed by bolts 30 to the side of the collet shaft 19 where the pipe 25 is attached. The bush 20 has a circular collar 31 in the middle as shown in FIG.
The lower surface of the bushing 20 is in contact with the upper surface of the collet receiver 22, and a nut 33 having a protrusion 32 is screwed into a threaded portion provided at one end of the bush 20, so that an opposing surface is formed between the protrusion 32 and the collar 31. The two interposed flanged bearings 34, 34 can be tightened. A diamond-shaped plate 36 having a circular portion 35 approximately in the center thereof that fits into the outer rings of the bearings 34, 34 is attached between the flanges of the two flanged bearings 34, 34. At one end of this plate 36, a shaft 37 having a male thread at the end stands perpendicularly to the surface of this plate 36, and at the other end, a cam follower 38 extends perpendicularly to the surface of this plate 36. and is rotatably provided. Further, in this plate 36, a spring post 39 is provided upright on the back surface located between the mounting portion of the cam follower 38 and the circular portion 35, and a spring post 41 is similarly provided on the tongue piece 40 provided on the collet receiver 22. By placing the spring 42 between the spring posts 39 and 41, a counterclockwise force is applied to the plate 36 in FIG. Stopper 4 installed at one end
3 (hereinafter this state will be referred to as the "contact state"). Further, in this embodiment, the center of the U-shaped portion 28 (coinciding with the axis of the shaft 37), the axis of the collect shaft 19, and the center of the cam follower 38 are arranged so as to be in a straight line A-A, In the contact state, the center line B- of the arm of this A-A
The angle α with respect to B is 15 degrees. Reference numeral 44 denotes a cam for rotating the collet shaft, the cam surface 45 of which is formed in an arc shape centered on the shaft 11, and the arm 10 rotates around the shaft 11 as described later.
When the cam follower 38 rotates 90 degrees, the cam surface 45
It is placed in such a position that it comes into contact with the As shown in FIG. 5, this collet shaft rotation cam 44 has a protrusion 46 provided at one end of the cam 44 that fits into a recess 48 provided in a cam support arm 47 fixed to a machine stand (not shown). However, in FIG. 3, it is possible to move left and right. Further, this movement is performed by rotating an adjustment screw 49 rotatably attached to the cam support arm 47 in either direction, and in the adjusted position, the cam is moved by screwing the stop bolt 50 into the screw provided in the recess 48. It is adapted to be fixed to a support arm 47.

Reference numeral 51 denotes a mounting board, which is sent one pitch at a time in the direction of arrow 52 by known means in synchronization with the pellet bonding operation.

Next, the operation of the pellet bonding apparatus constructed as above will be explained.

1) When the arm 10 moves as indicated by the arrow 12, the pellet 27 on the pellet mounting table 26 is attracted by the suction portion 18 of the collect shaft 19.

At this stage, one side of the plate 36 is attached to the stopper 4.
Since it is in contact with 3, the collect shaft 19
does not rotate about its axis.

2) By the movement of the arm 10 in the direction of the arrow 13, the collect shaft 19 is raised, and the pellet 27 is suctioned and held by the suction portion 18. FIG. 4 shows this state.

Even at this stage, one side of the plate 36 is attached to the stopper 43.
Since the collet shaft 19 remains in contact with the collet shaft 19, the collet shaft 19 does not rotate about its axis.

3) Movement of the arm 10 as indicated by the arrow 14, ie, the arm 10 swings 90 degrees in this embodiment about the axis 11, to move the pellet 27 onto a predetermined position on the mounting substrate 51.

At this stage, the cam follower 38 comes into contact with the cam surface 45 of the collet shaft rotation cam 44, and the shaft 37
The diamond-shaped plate 36 rotates in the opposite direction to the biasing force of the spring 42, that is, clockwise in FIG.
I will be separated from 3. This state is shown by the solid line in FIG. This allows this shaft 37
a follower plate 2 having a U-shaped portion 28 fitted with the
9 also follows the movement of the diamond-shaped plate 36 and rotates clockwise, and since this follower plate 29 is integrated with the collect shaft 19, the collect shaft 1
9 will also rotate clockwise around its axis.

4) The arm 10 moves in the direction of the arrow 15 to press the pellet 27 held in the suction part 18 of the collect shaft 19 to a predetermined position on the mounting board 51 while maintaining the state described in 3) above, and bonding is performed. Do this.

5) When the arm 10 moves in the direction of the arrow 16, the suction part 18 of the collect shaft 19 releases the pellet 27, and the arm 10 as a whole rises while maintaining the above-mentioned state in 3), collecting pellets in one go. Bonding work is completed.

6) The arm 10 moves as indicated by the arrow 17 to position the suction unit 18 above the pellet mounting table 26.

At this stage, the cam follower 38 is separated from the cam surface 45 of the cam 44, and the collet shaft 19 is attached to the spring 4.
3 or 5 due to the biasing force shown in FIG. 2, and this rotation is stopped when one side of the diamond-shaped plate 36 comes into contact with the stopper 43. Further, another pellet is already positioned below this suction part 18 by a moving table (not shown), and the mounting board 51 is fed one pitch in the direction of arrow 52, and the next pellet of the mounting board 51 is moved. A pellet bonding location is located.

Thereafter, by repeating the operations 1) to 6) described above, the pellet bonding work is performed in sequence.

FIG. 7 shows an example in which wire bonding work was performed after bonding the pellet 6 shown in FIG. 2 to the mounting board 1 using the present invention.
As is clear from the comparison with the figure, there is little variation in wire length, which allows very good bonding between the pad and the external lead.

Furthermore, the solid line in Figure 6 indicates that the collet shaft rotates by 45 degrees (the angle β formed by lines A-A and A'-A' in Figure 6) with respect to its axis in step 3) above. Although the cam surface 45 is shown adjusted to position C, the position D of the cam surface 45 indicated by the dashed line in the same figure means that even if the cam follower 38 comes into contact with the cam surface 45, the collect shaft 19 This is a position where the cam surface 45 does not rotate sharply, in other words, one side of the plate 36 and the stopper 43 maintain contact, and the position of the cam surface 45 can be adjusted within the range of C to D by appropriately rotating the adjusting screw 49. By adjusting the rotation angle of the collet shaft 19, it is possible to freely set the rotation angle between 0 degrees and 45 degrees.

Further, in the above embodiment, since the collet shaft rotation cam 44 which acts to rotate the collet shaft 19 is provided in the movement path of the arm 10, there is no need to provide a special rotational drive source for the arm 10 itself. This makes it possible to reduce the weight of the arm 10 and to speed up pellet bonding work.

In the above-mentioned embodiment, the collect shaft rotates clockwise with respect to its axis in FIG. 3 or FIG.
It is also possible to rotate it counterclockwise by changing the positions of 4 and cam follower 38.

Furthermore, although an example in which the present invention is applied to a swing type bonding device, that is, a bonding device that is performed by swinging an arm, has been described, it may also be applied to other types, such as a straight type in which the arm reciprocates between a pellet mounting table and a mounting board. It is possible.

(Effects of the Invention) According to the present invention, pellets can be bonded at various desired mounting angles by extremely simple adjustments such as adjusting the position of the collet rotation cam. Therefore, even with pellets in which the pads are scattered on the pellet, the subsequent wire bonding work can be carried out satisfactorily, and the pattern design of the pads on the pellet becomes easy.

Furthermore, since the collet shaft is rotated by a cam provided on the movement path of the arm, there is no need to provide a special rotation drive source for the arm itself.
This makes it possible to reduce the weight of the arm and speed up pellet bonding work.

[Brief explanation of drawings]

1 and 2 are plan views showing the positional relationship between pellets bonded by conventional pellet bonding work and a mounting board, and FIG. 3 is a plan view of a rotating type pellet bonding apparatus to which the present invention is applied. , FIG. 4 is a partially cutaway right side view of FIG. 3, FIG. 5 is a cross-sectional view of FIG. 3, FIG. 6 is a plan view showing the rotating state of the collet shaft, and FIG. 2A and 2B are plan views showing the positional relationship between the pellets bonded using the above-described method and the mounting substrate. 10...Arm, 11...Shaft, 18...Adsorption section, 19...Collection shaft, 22...Collection receiver, 27...Pellet, 36...Plate (operating plate),
38...Come follower, 43...Stopper, 4
4... Cam for collet shaft rotation, 45... Cam surface,
47...Cam support arm, 49...Adjustment screw (adjustment means), 51...Mounting board.

Claims (1)

[Claims] 1. A pellet bonding device having an arm that reciprocates between a pellet suction position and a bonding position, and a collet shaft rotatably supported at one end of the arm about its axis, the arm and an elastic body provided between the collet shafts and urging the collet shafts to rotate in one direction;
A stopper provided on the arm side to prevent rotation of the collet shaft in the one direction at a fixed position, an actuating plate that rotates integrally with the collet shaft, and a cam follower attached to the actuating plate. The moving path of the arm includes a collet shaft rotating cam that operates on the cam follower to rotate the actuating plate in the other direction when the arm moves to the bonding position, and the cam follower is attached to the cam. A pellet bonding device comprising: adjusting means for moving and adjusting the cam in a direction that changes the rotation angle of the actuating plate when the cam comes into contact with the cam.