JPS61290730A - Bonding apparatus - Google Patents

Abstract

PURPOSE:To do precise bonding operation of a bonding tool, by sensing the landing onto a given position of the tool fixed to the bonding arm, through the use of a non-contacting sensor and a moving member being possible to be displaced with the arm. CONSTITUTION:By moving the XY table 1, the lower end of the wedge 13 is set on a given position on a pellet 19. The up-and-down moving block 3 is moved down, and the lowering operation of the wedge 13 is stopped precisely at a predetermined position through the use of a non-contacting sensor 14b and a numerical controlling section 5a. To the tip side of the bonding wire 17, supersonic vibration is applied through the horn 12, to pressure-weld the wire 17 to the bonding pad of the pellet 19. Next, the wire-clamp 15 is released and the up-and-down moving block 3 is raised while the XY table 1 is moved, being set at the next position to repeat the same operation. In this way, the non-contacting sensor consisting of the moving member 14a and sensor section 14b senses the landing of the bonding tool precisely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a bonding technique, and particularly to a technique that is effective when applied to a wire bonding process in the assembly of semiconductor devices.

[Background Art] For example, when electrically connecting a pellet fixed on a tab of a lead frame and a lead in the assembly process of a semiconductor device, a bonding wire is pressed against the bonding pad of the pellet or the lead frame to make a crimping bond. It is important to accurately grasp the landing of a bonding tool such as a wedge on the bonding pad or lead frame, and to accurately stop the lowering movement of the vertically movable block to which the bonding tool is fixed via the bonding arm. This is important from the viewpoint of preventing collision between the wedge that is lowered onto the pellet loading pad or lead frame by the lifting and lowering of the block, and the pellet loading pad or lead frame.

For this reason, the bonding arm to which the bonding tool is fixed is rotatably attached to a rotating shaft provided on the vertical movement block, and the rotation of the bonding arm due to the bonding tool landing is detected by the following mechanism. is possible.

That is, electrical circuit contacts are provided at a predetermined part of the bonding arm that rotates and at a part that is fixed independently of the bonding arm, and the contacts are closed by biasing the bonding arm with a spring or the like. The contact is configured so that when the bonding arm is rotated due to the landing of the bonding tool, the contact point is opened, and the landing of the bonding tool is detected from the outside, and the entire bonding arm to which the bonding tool is fixed is raised and lowered. The lowering of the vertically movable block is returned to the drive mechanism of the vertically movable block to stop the lowering of the vertically movable block at a predetermined position.

However, with the above-mentioned structure having electrical contacts, it is not possible to accurately detect the point of contact opening operation, that is, the point of landing of the bonding tool, due to contact wear or minute irregularities, and the The stopping position of the vertically movable block that lowers the bonding tool to the bonding area becomes unstable, resulting in inaccurate bonding operations of the driven bonding tool, so-called chattering. The inventor has found that there are drawbacks such as reduced operating time of the device.

The unstable bonding operation of the bonding tool as described above can cause poor bonding between the bonding wire and the pellet bonding band or lead frame, and damage to the pellet caused by the bonding tool.
This reduces the reliability of wire bonding.

The literature explaining wire bonding technology is "Electronic Materials J, November 1982 issue, special edition, published by Kogyo Chosukaikai Co., Ltd., November 15, 1982.
There are 163 to P168.

[Object of the Invention] An object of the present invention is to provide a bonding technique that allows highly reliable bonding.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the Invention] A brief overview of typical inventions disclosed in this application is as follows.

That is, the landing of the bonding tool fixed to the bonding arm on a predetermined bonding site is performed using a mover fixed to the bonding arm that is displaced by the landing of the bonding tool and displaced together with the bonding arm, and a movable element that is provided independently of the bonding arm. By adopting a structure in which the displacement of the movable element is detected by a non-contact sensor mechanism consisting of a sensor section that detects the displacement of the movable element without contacting the movable element, instability of mechanical contact operations such as contacts can be reduced. This prevents inaccurate detection of the landing timing of the bonding tool due to the above reasons, thereby realizing accurate bonding operation of the bonding tool and obtaining highly reliable bonding results.

[Example] FIG. 1 is a schematic cross-sectional view of a wire bonding apparatus that is an example of the present invention.

In FIG. 1, a bonding head 2 is provided on an XY table 1 that is movable in a horizontal plane, and a vertical movement block 3 is provided inside this bonding head 2.
is configured to be able to be raised and lowered by an inner shaft 4 provided vertically.

A ball screw mechanism 6 is attached to the side surface of the vertically movable block 3 to convert the rotational motion of a servomotor 5 fixed to the bonding head 2 side into vertical linear motion. The vertically movable block 3 is configured to be moved vertically by a predetermined distance by rotating the block 5 by a predetermined amount in a predetermined direction.

Furthermore, a bonding arm 8 is provided inside the vertically movable block 3 and is rotatable in a vertical plane about a rotating shaft 7 horizontally fixed to the vertically movable block 3 .

One end of the bonding arm 8 is attached to the vertical movement block 3
The bonding arm 8 is configured to be biased upward by the voice coil motor 9 fixed to the bonding arm 8 and to apply a counterclockwise rotating force around the rotating shaft 7, and is opposed to the voice coil motor 9 via one end of the bonding arm 8. At this position, it abuts against a stopper 10 fixedly provided on the vertically movable block 3.

Furthermore, a horn 12 connected to the ultrasonic oscillator 11 is provided on the other end side of the bonding arm 8, and a wedge 13 is attached almost vertically to the tip of the horn 12 that extends outside the vertical movement block 3. Fixed.

The vertical movement of the movable block 3 causes the wedge 13 fixed to the tip of the horn 12 to move up and down, and when the wedge 13 lands on the bonding part, the wedge 13 is moved from the bonding part to the wedge 13. The voice coil motor 9 is applied to the bonding arm 8 to which the horn 12 is fixed by the reaction force applied.
The bonding arm 8 is slightly rotated clockwise against the urging force of the voice coil motor 9, and a bonding load corresponding to the urging force of the voice coil motor 9 is applied to the wedge 13.

In this case, a mover 14a (non-contact sensor mechanism) made of a conductor is fixed to one end of the bonding arm 8, and is configured to be vertically displaced by rotation of the bonding arm 8. A sensor section 14b (non-contact sensor mechanism) fixed to the vertically movable block 3 is provided above the movable element 14a so as to face the movable element 14a without contacting it.

The sensor section 14b is composed of, for example, a high-frequency magnetic field generation mechanism, and eddy current loss occurs on the sensor section 14b side due to eddy currents generated in the mover 14a by the magnetic field applied from the sensor section 14b to the mover 14a. is generated,
Since this eddy current loss is changed by a change in the distance between the sensor section 14b and the mover 14a, the sensor section 14b
The displacement of the mover 14a in the vertical direction relative to the bonding arm 8, that is, the landing of the wedge 13 fixed to the bonding arm 8 via the horn 12, is detected when the mover 14a and the sensor section 14b are not in contact with each other.

The rotation of the bonding arm 8 detected by the sensor section 14b, that is, the landing of the wedge 13, is controlled by the numerical control mechanism 5a of the servo motor 5, which drives the vertical movement block 3 that raises and lowers the wedge 13 via the bonding arm 8. The structure is such that the stop position of the lowering movement of the vertically movable block 3, that is, the lowering position of the wedge 13 relative to the bonding portion, is accurately controlled.

Further, a wire clamper 15 is fixed to the vertically movable block 3, and the tip thereof is located near the wedge 13.

A bonding wire 17 made of aluminum or the like is paid out from the spool 16, passes through a part of the horn 12, and is then inserted into the wire clamper 15 and supplied to the lower end of the wedge 13. At a predetermined time, the wire clamper 15 Driven by a wire clamper drive mechanism (not shown), the bonding wire 17 is cut from the bonding site and the lower end of the wedge 13 is cut by reciprocating in the direction in which the bonding wire 17 is pulled out while the bonding wire 17 is being clamped. The structure is such that the bonding wire 17 is set to.

The lower end of the wedge 13 is configured such that the side surface of the bonding wire 17 to be centered is exposed on the lower end surface of the wedge 13, and the side surface of the bonding wire 17 exposed on the lower end surface of the wedge 13 is Ultrasonic vibrations are applied to a predetermined bonding site through the horn 12 while being pressed from above, and the side surface of the bonding wire 17 is crimped to the predetermined bonding site.

Furthermore, a wedge 13 fixed to the tip of the horn 12
Below is a θ table 1 that is rotatable in the horizontal plane.
8 is provided, and pellets 1 are placed on this θ table 18.
A lead frame 20 (bonding part) with a lead frame 9 (bonding part) mounted at the center is placed,
It is configured to be rotated together with the θ table 18 at a predetermined time.

By combining the horizontal displacement by the XY table 1 and the vertical displacement by the vertical movement block 3, a predetermined bonding operation of the wedge 13 fixed to the bonding arm 8 via the horn 12 is realized, and a pair of pellets Every time bonding is performed between the bonding pad 19 and the bonding portion of the lead frame 20 using the bonding wire 17, the θ table 18 on which the lead frame 20 is placed is rotated by a predetermined angle to continue the bonding operation. It is something that

The operation of this embodiment will be explained below.

First, by appropriately moving the XY table 1, the lower end of the wedge 13 is positioned directly above a predetermined pounding pad of the pellet 19.

At this time, the tip of the bonding wire 17 is set at the lower end of the wedge 13 so that it protrudes from the side surface of the lower end of the wedge 13 by a predetermined length in a substantially horizontal direction.

Next, the vertical movement block 3 is moved downward, and the wedge 1
3 is lowered and lands on the pounding pad of the pellet 19, and the wedge 13 causes the voice coil motor 9 to slightly rotate the bonding arm 8 against the urging force by the reaction force from the pounding pad, and the bonding arm 80 The rotation is detected by the non-contact sensor 14b and transmitted to the numerical control unit 5a, the rotation of the servo motor 5 that drives the vertical movement block 3 is stopped, and the downward movement of the vertical movement block 3, that is, the downward movement of the wedge 13 is stopped. Stops accurately at a predetermined position.

The side surface of the tip end of the bonding wire 17 exposed on the lower end surface of the wedge 13 is pressed by the bonding band of the pellet 19 with a predetermined bonding load depending on the urging force of the voice 4 coil motor 9 via the horn 12. Ultrasonic vibrations are applied, and the side surface of the tip end of the bonding wire 17 is pressed against the bonding pad of the pellet 19.

Next, the wire clamper 15 is opened and the bonding wire 17 can be paid out, and then the vertical movement block 3 is raised and the XY table 1 is moved in the horizontal direction, so that the wedge 13 is allowed to pay out the bonding wire 17 and lead it. After being moved directly above the bonding site of the frame 20, the vertically movable block 3 is moved downward again, and the wedge 13 is lowered and lands on the bonding site.

At this time, the wedge 13 slightly rotates the bonding arm 8 against the urging force of the voice coil 9 due to the reaction force from the bonding part, and this bonding arm 8
The rotation is accurately detected by the non-contact sensor 14b and transmitted to the numerical control unit 5a, and the lowering operation of the vertical movement block 3 driven by the servo motor 5, that is, the lowering operation of the wedge 13, is accurately detected at a predetermined position. will be stopped.

Then, the side surface of the bonding wire 17 exposed on the lower end surface of the wedge 13 is pressed against the bonding site of the lead frame 20 with a predetermined bonding load according to the urging force of the voice coil motor 9, and the ultrasonic vibration is transmitted via the horn 12. is applied and crimped.

In this way, when the wedge 13 lands on the bonding portion, the movable element 14a is displaced together with the bonding arm 8 which is rotated by the landing of the wedge 13, and the displacement of the movable element 14a is detected without contacting the movable element 14a. Because the structure allows accurate detection by a non-contact sensor mechanism consisting of a sensor section 14b, for example, the wedge 13 may
This prevents inaccurate landing detection, and makes it possible to accurately control the stop position of the downward movement of the vertical movement block 3, so that the wedge 13, which is raised and lowered by the vertical movement of the vertical movement block 3 during bonding, The bonding load that presses the bonding wire 17 against the bonding pad of the pellet 19 and the bonding site of the lead frame 20 is maintained appropriately, and collisions between the lower end of the wedge 13 and the pellet 19 and the lead frame 20 are avoided, thereby increasing customer satisfaction. High quality bonding is performed.

Furthermore, since the movable element 14a and the sensor part 14b are structured so as not to be in mechanical contact, maintenance management due to wear of the contact parts is unnecessary, and a decrease in the operating rate of the bonding apparatus is prevented.

Next, the wire clamper 15 restrains the bonding wire 17 and is moved a predetermined distance in the opposite direction to the direction in which the bonding wire 17 is pulled out, that is, in the direction away from the bonding site of the lead frame 20. The bonding wire 17 is cut near the bonding site.

Next, the vertical movement block 3 is raised, the wedge 13 is raised, and the wire clamper 15 restraining the bonding wire 17 is moved by a predetermined distance in the direction in which the bonding wire 17 is paid out, and the wire clamper 15 is The distal end of the bonding wire 17 which has been restrained is set in a state where it is extended by a predetermined length from the lower end of the wedge 13, in preparation for the next bonding operation.

Next, the θ table 18 is rotated by a predetermined angle, and the above-described series of bonding operations are repeated, and the pellet 1
The bonding pad 9 and the bonding portion of the lead frame 20 are reliably bonded and electrically connected by the bonding wire 17.

[Effects] (1) When the bonding tool fixed to the bonding arm lands on a predetermined bonding site, the movable element is fixed to the bonding arm and is displaced together with the bonding arm, which is displaced by the landing of the bonding tool, and the bonding Since it is a structure in which detection is performed by a non-contact sensor mechanism consisting of a sensor section that is provided independently of the arm and detects the displacement of the movable element without contacting the movable element, for example, instability of mechanical contact can be detected. This prevents inaccurate detection of the bonding tool's landing due to such factors, and the operation of the drive mechanism that drives the bonding tool is accurately controlled, allowing accurate bonding operation of the bonding tool and improving reliability. It is possible to obtain high bonding results.

(2) As a result of (1) above, the mover and the sensor section are not in mechanical contact, so maintenance management due to wear of the contact section is unnecessary, and a decrease in the operating rate of the bonding device is prevented. .

(3) As a result of the il+, the product yield is improved.

(4) As a result of the above (11 to (3)), productivity in the bonding process is improved.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, the bonding tool is not limited to ultrasonic bonding using a wedge, but may also be pole bonding using a capillary.

[Field of Application] In the above explanation, the invention made by the present inventor was mainly applied to wire bonding technology, which is the field of application that formed the background of the invention, but the invention is not limited thereto. It can also be widely applied to pellet bonding technology for mounting on lead frames.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a wire bonding apparatus that is an embodiment of the present invention. l...XY table, 2...bonding head,
3... Vertical movement block, 4... Guide shaft, 5... Servo motor, 5a... Numerical control section, 6... Ball screw mechanism, 7... Rotating shaft, 8... Bonding Arm, 9...Voice coil motor, IO...Stopper,
11... Ultrasonic oscillator, 12... Horn, 13...
- Wedge (bonding tool), 14a... Mover (non-contact sensor mechanism), 14b... Sensor section (non-contact sensor mechanism), 15... Wire clamper, 16...
・Spool, 17...Bonding wire, ]8...
- θ table, 19... pellet (bonding site), 2o... lead frame (bonding site).

Claims (1)

[Scope of Claims] 1. A mover fixed to the bonding arm and displaced together with the bonding arm so as to be displaced when the bonding tool fixed to the bonding arm lands on a predetermined bonding site; is provided with a non-contact sensor mechanism consisting of a sensor section which is provided independently and detects the displacement of the movable element without contacting the movable element, and this non-contact sensor allows the bonding tool to be moved to a predetermined bonding site. A bonding device that detects landing without contact. 2. The bonding apparatus according to claim 1, wherein the mover is made of a conductor, and the sensor part is made of a high-frequency magnetic field generating mechanism. 3. The bonding apparatus according to claim 1 or 2, wherein the bonding apparatus is a wire bonding apparatus.