JP3016223U - Wedge tool for ultrasonic bonding - Google Patents

Abstract

(57) [Abstract] [Purpose] Improving the reliability of ultrasonic bonding [Configuration] A non-slip groove that is orthogonal to the axis parallel to the inner surface of the wire gripping groove of the wedge tool for ultrasonic bonding is provided. [Effect] Variations in strength are reduced, and at the same time, the cycle for tool regeneration and cleaning is lengthened and maintenance becomes easier. In addition, the tool life is extended.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a wedge tool used in a wire bonding device which is an assembly device for semiconductor devices.

[0002]

[Prior art]

 Wire bonding is used for electrical connection between electrodes on a semiconductor chip and package terminals. There are two types of wire bonding: ball bonding, which mainly performs thermosonic bonding of Au wires with a capillary tool, and wedge bonding, which mainly performs ultrasonic bonding of Al wires with a wedge tool. Wedge bonding, which mainly uses Al wires, is normally performed at room temperature and is solid-phase bonding using ultrasonic vibration. When the Al wire is pressed against the Al electrode of the semiconductor chip with a wedge tool and ultrasonic vibration is applied, the ultrasonic vibration from the tool is transmitted to the Al wire and the oxide film and the contaminated layer vibrate at the interface between the Al wire and the Al electrode. It is thought that the aluminum wire and Al electrode will eventually be joined, due to the fact that Al is softened by ultrasonic vibration and deforms due to plastic flow, which causes the contact surface area to increase. There is. Generally, ultrasonic vibrations are converted from electrical signals by ultrasonic transducers. The generated vertical vibration is transmitted to the wedge tool via the horn. The wedge tool oscillates in bending mode, transferring energy to the tip of the tool. The tip of the tool vibrates in parallel to the joint surface (lateral vibration). The tool tip groove is oriented parallel to the horn so that the vibration direction is parallel to the centerline of the pressed wire.

[0003]

[Problems to be solved by the device]

 In order to increase the bonding strength of ultrasonic bonding, the following things happen when the amplitude of ultrasonic vibration is increased or the ultrasonic energy is increased under an appropriate pressing pressure, and the bonding strength becomes stable. There was a problem that it did not rise. 1. Although the crushing of the Al wire is progressing, the joint strength cannot rise proportionally. 2. The wire may retract or come out in front. Originally, where the Al wire and the surface to be joined should be rubbed by ultrasonic vibration, the same thing happened between the tool and the Al wire, and only the Al wire shook. This is a phenomenon in which the Al wire slips and moves. In ultrasonic bonding, it is expected that ultrasonic energy will be mainly used between the Al wire and the surface to be bonded. However, since the ultrasonic vibration is not sufficiently transmitted from the tool to the Al wire, It is considered that energy loss occurs, the joint strength cannot be increased, and the Al wire slips.

[0004]

[Means for solving problems]

 In an ultrasonic bonding wedge tool having a groove for gripping a bonding wire and pressing it against a surface to be bonded, at least one non-slip groove is provided on an inner surface of the groove in a direction perpendicular to an axis parallel to the inner surface.

[0005]

[Action]

 By providing a non-slip groove on the inner surface of the groove that presses the wire, the friction coefficient increases due to the effect of the edge, slippage at the initial stage of bonding does not occur, and in addition, due to ultrasonic vibration at the initial stage As a result of softening, Al plastically deformed into a shape in which the groove provided on the inner surface was hard to fit in, and the tool and the Al wire became ultrasonically vibrated as a unit rather than slipping. As a result, the movement of the Al wire due to the progress and slippage of the Al wire alone was also stopped.

[0006]

【Example】

 Since the shape of the ultrasonic bonding wedge tool is already known, only the end shape, which is a feature of the present invention, is shown here, and an enlarged perspective view is shown for easy viewing. In FIG. 1, 1 is a basic tool, 2 is a V groove for holding a wire, and 3 is a non-slip groove according to the present invention. The anti-slip groove 3 is perpendicular to an axis 5 parallel to the inner surface of the V groove 2 and forms an edge 4 with the inner surface of the V groove 2. FIG. 2 shows another embodiment devised so as to be easier to process than FIG. 1, and two anti-slip grooves 3 are provided. The numbers correspond to those in FIG. FIG. 3 shows a tool contact mark of a wire bonded using the tool of FIG. The contact mark is sometimes called the footprint footprint. In the figure, 6 is a rib formed by the anti-slip groove 3 of FIG. The rib 6 plays a role similar to the meshing of the teeth of the gear that transmits the rotary motion. In other words, the vibration transmission mechanism at the time of ultrasonic bonding is changed from friction transmission accompanied by slippage to positive movement. The width and depth of the non-slip groove 3 provided on the inner surface of the gripping groove 2 that presses the wire are appropriately set according to the wire diameter, but the groove width is 1/10 to 1 / the wire diameter. A range of 3 is suitable.

[0007]

[Effect of device]

 The present invention eliminates the phenomenon of slipping between the tool and the Al wire during ultrasonic bonding, greatly increasing the bonding strength, and exerts a remarkable effect in increasing the reliability of semiconductor devices. Another effect is that the reduction of slippage reduces the amount of Al adhering to the tool, prolongs the cycle of tool regeneration cleaning, and prolongs the life of the industry.

[0008]

[Brief description of drawings]

FIG. 1 is a perspective view of a tool end portion showing an embodiment of the present invention.
FIG. 2 is a perspective view of a tool end portion showing another embodiment of the present invention. FIG. 3 is a top view showing a tool contact mark of a wire bonded by using the tool shown in FIG.

[Explanation of symbols]

 1. ． ． ． Tool base 2. ． ． ． Gripping groove 3. ． ． ． Non-slip groove 4. ． ． ． Edge 6. ． ． ． Tool contact mark on the wire

Claims (1)

[Scope of utility model registration request] 1. A wedge tool for ultrasonic bonding, having a groove for gripping a bonding wire and pressing it against a surface to be bonded, wherein at least one cleat is provided on the inner surface of the groove in a direction perpendicular to an axis parallel to the inner surface. Wedge tool featuring groove