JPS6138185Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a wire bonding device used in the manufacturing process of semiconductor devices, and particularly relates to an ultrasonic device for bonding a wire tip to a semiconductor chip electrode, lead frame, etc. using ultrasonic waves. This invention relates to improvements in wire bonding equipment.

In a die-bonded semiconductor chip, an electrode on the semiconductor chip and the tip of a lead frame are electrically connected using a wire such as a gold wire, and a lead wire for connection to an external device is led out.

As one of the wire bonding methods for manufacturing the above-mentioned semiconductor device, a method using ultrasonic waves has been put into practical use. Bonding is performed by applying ultrasonic vibrations to a capillary for guiding the wire, and pressing the capillary from which the wire has been led out to the end of the lead frame to be bonded while applying ultrasonic vibrations. In the thermocompression bonding method, which has been widely used in the past, when pressing a wire against the end of a lead frame, the capillary is heated to preheat the wire in order to improve bonding performance. Preheating the wire in the process of ultrasonic wire bonding is thought to improve bonding performance, but it is necessary to install a heater to heat the capillary, and in order to install the heater, it is necessary to install a heater inside the horn. There was a risk that stable bonding work could not be performed due to a change in the ultrasonic generation mode of the wire, and a device for ultrasonic wire bonding by heating the capillary had not yet been put into practical use.

The present invention was devised in view of the problems of the conventional devices described above, and provides an ultrasonic wire bonding device in which a heater for heating a capillary can be stably fixed to an ultrasonic horn. Next, the present invention will be explained in detail using the drawings.

In Fig. 1, 1 is a wire such as a thin gold wire for electrically connecting an electrode on a semiconductor chip to a lead frame, etc., and the wire 1 is guided to a capillary 2 with a guide hole bored in the center. and guided onto a chip electrode or lead frame. The capillary 2 is integrally fixed to the tip of the ultrasonic horn 3. The ultrasonic horn 3 stably transmits ultrasonic waves 4 generated by an ultrasonic oscillation circuit (not shown) provided at the other end. Capillary 2 above
A capillary heater 5 is detachably provided in the vicinity of the wire lead-out hole, and heats the wire 1 led out through the heated capillary 2. The capillary heater 5 is made of, for example, a tantalum wire wound in a spiral shape, and the surface thereof is coated with heat-resistant paint. FIGS. 2a and 2b are diagrams showing the capillary heater 5 portion, which is formed into a donut shape through which the capillary 2 can be inserted, and a lead wire 6 for power supply is led out. According to the capillary heater 5 described above, the capillary 2 can be heated with a small volume heater.
can be heated, has little effect on ultrasonic vibration, and hardly narrows the field of view for observing the bonding situation. The heater 5 can be arranged along the outer shape of the capillary 2, and can be brought close to the capillary 2 with good adhesion to efficiently supply heat, and the temperature of the heater 5 can be easily controlled by controlling the current. Can be done.

The capillary heater 5 is fixed to the ultrasonic horn 3 to ensure its retention, but in order to stabilize the ultrasonic waves 4 transmitted to the horn 3, the capillary heater 5 is fixed at a selected position that will become a node of the generated ultrasonic waves. It can be attached with tool 7. Since the ultrasonic nodal portion is selected, even if the fixture 7 is attached, there will be very little change in the mode, and there will be almost no hindrance to the operation of ultrasonic wire bonding.

Figure 3 is a diagram showing the relationship between capillary temperature and bonding achievement rate. Although it varies somewhat depending on the metal material of the lead frame, an excellent bonding rate can be obtained at temperatures above 200℃, preferably around 250℃. . If the temperature exceeds 300℃, the mechanical strength of the thin gold wire will decrease, and if the metal that serves as the lead frame is mounted on a printed circuit board, the substrate will soften due to the heat, making it ineffective even if ultrasonic waves are applied. This is undesirable as it leads to a situation in which the company is unable to fully demonstrate its capabilities.

The above embodiment has been explained using ball bonding, in which a ball is formed at the tip of a wire for bonding, but the present invention can also be applied to wedge bonding or stitch bonding, in which the wire is flattened at the tip of a capillary, etc., and then bonded. Can be applied.

As described above, according to the present invention, a capillary for ultrasonic wire bonding can be heated without impairing ultrasonic vibration, and the reliability of wire bonding can be improved.

[Brief explanation of the drawing]

Figure 1 is a side view of an embodiment according to the present invention, Figures 2a and b are side views and plan views showing the capillary heater portion of the same embodiment, and Figure 3 is the relationship between capillary temperature and bonding achievement rate. FIG. 1... Wire, 2... Capillary, 3... Ultrasonic horn, 5... Capillary heater, 7...
Fixture.

Claims (1)

[Scope of utility model registration request] A capillary with a hole for guiding the wire, a horn that transmits ultrasonic vibration to the capillary, a heater that heats the vicinity of the wire lead-out hole of the capillary, and a horn that uses the ultrasonic waves generated in the horn to heat the heater. An ultrasonic wire bonding device comprising: a fixture for fixing the wire to the wire;