JPS6042019B2 - Ultrasonic wire bonding equipment - Google Patents

Abstract

PURPOSE:To compose the titled apparatus of high reliability without using the mechanical contact by utilizing damping of output current from the ultrasonic oscillator to the vibrator in time of contact of the capillary tip to the bonding face. CONSTITUTION:The vibrator 1 is vibrated by the ultrasonic output potential from the ultrasonic oscillator 4 via the transformer 5 and related in the arrow direction around the sustaining shaft 3 by the driving device (not illustrated) and the metal fine wire 12 is bonded to the bonding face 12a of a pellet 11 by pushing with the capillary tip 2. The value of applied current to the vibrator 1 is detected as the potential value by the detector 22 on said apparatus, this value is compared to the standard potential value. When the difference exceeds the set value, the driving device is controlled by the controller 23 and the descent of the capillary tip 2 is stopped and the bonding operation is made to do.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic wire bonding apparatus provided with means for detecting a contact surface of a capillary chip to a bonding surface.

Conventional ultrasonic wire bonding equipment of this type has a first
The configuration was as shown in the schematic diagram shown in the figure.

Reference numeral 1 denotes a vibrator, which has a capillary tip 2 attached to its tip, and is rotated in the direction of arrow A about a support shaft 3 by a drive device (not shown).

Reference numeral 4 denotes an ultrasonic oscillator which applies an ultrasonic output voltage to the vibrator 1 via a transformer 5 to generate ultrasonic vibrations.

6 is a detection contact, consisting of a fixed contact 7 and a movable contact 8,
This movable contact is connected to a support arm 9 attached to the rear end of the vibrator 1.
and is always in contact with the fixed contact 7.

A detector 10 is connected to the detection contact 6 and outputs a detection signal when the contact is opened.

Reference numeral 11 denotes a pellet such as a semiconductor element, which serves as a bonding object and is bonded with a thin metal wire 12.

12a is a bonding surface.

In the conventional device described above, when the vibrator 1 is rotated in the direction of arrow A by the drive device and the lower end of the capillary chip 2 comes into contact with the bonding surface 12a, the support arm 9 is also rotated in the direction of arrow B, and the movable contact 8 is detached from the fixed contact 7 and the detection contact 6
becomes open. Then, a signal is output from the j detector 10, and a controller (not shown) operates the drive device, causing the vibrator 1 to
rotation is stopped. As described above, the means for detecting the contact surface of the capillary chip 2 with the bonding surface of the conventional apparatus relies on turning on and off the detection contact 6 which is mechanically operated, and has the following drawbacks. Wire bonding work has become faster and the capillary tip 2 is repeatedly moved up and down at high speed, but this causes large wear on the fixed contact 7 and movable contact 8 of the detection contact 6, and also reduces the responsiveness. It wasn't good. In this invention, when a load is applied to the vibrator due to the contact surface of the capillary chip to the bonding surface,
Utilizing the fact that the output current of the ultrasonic transmitter attenuates, a means is provided to detect a change in this output current and detect a contact surface,
It is an object of the present invention to provide an ultrasonic wire bonding device that can detect a contact surface with high reliability and responsiveness without using a contact point, and can quickly respond to high-speed wire bonding.

FIG. 2 is a schematic configuration diagram of an ultrasonic wire bonding device showing the principle of the present invention, and shows 1 to 5, 11, 12, 12
A is the same as the conventional device described above, but the contact surface detection means is different.

20 is a low-resistance element connected in series from the transformer 5 to the vibrator 1, and 21a and 21b are the low-resistance elements 2.
By measuring the voltage between these terminals with measurement terminals drawn out from both ends of the oscillator 1, it is possible to detect changes in the current in the supply circuit to the vibrator 1.

Figure 3 shows terminals 21a and 2 in front of the contact surface of capillary chip 2.
This is a voltage waveform between 1b and 1b.

(2) is the voltage value, and t is the time. When the capillary chip 2 comes into contact with the bonding surface 12a, the load to which the ultrasonic energy vibrates increases at that moment, so that the terminals 21a, 21b
The voltage of the voltage waveform between them drops as shown in FIG.
This invention applies this phenomenon, and FIG. 5 shows an ultrasonic wire bonding device according to an embodiment. A schematic diagram of the equipment is shown.

A detector 22 is inserted into the circuit from the transformer 5 to the vibrator 1, and detects changes in current.

That is, the value of the output current of the ultrasonic oscillator 4 that was output before the contact surface of the capillary chip 2 is measured as a voltage value, and is stored in the temporary storage means, and this reference voltage value and the measured voltage value thereafter are measured. When the voltage difference exceeds a set value, it is detected as a contact surface and a detection signal is sent to the controller 23 of the wire bonding apparatus. As a result, the controller 23 operates a drive device (not shown) to stop the gear/pillar chip 2 from lowering and performs the bonding operation.
Note that the above detection means can also be applied as follows.

The ultrasonic energy value necessary for crimping is stored as a voltage value as described above, and each time an ultrasonic wave is output, the stored voltage value is compared and returned to the ultrasonic oscillator 4 to correct the output. In this way, the output can be stabilized as the ultrasonic output changes over time. Further, in the above embodiment, the change in the output current from the ultrasonic oscillator 4 is measured as a voltage value, and the
Although the comparison was made with a memory value, the contact surface may be detected by measuring the waveform due to the output current and comparing it with a stored waveform before the contact surface.

Furthermore, as the electric element based on the output current from the ultrasonic oscillator 4, in the above embodiment, a voltage value or a voltage waveform is taken, or a current value is taken, but the current value may be taken and detected.

Furthermore, the device according to the present invention can also be used in the case of an ultrasonic thermocompression wire bonding device.

As described above, according to the present invention, a detector is inserted into the output supply circuit from the ultrasonic oscillator to the vibrator, and a change in the output current is detected to detect the contact surface. The device can be easily constructed, there is no problem of contact wear, the contact surface can be detected with good responsiveness and reliability, and it can be used to increase the speed of wire bonding. .

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a conventional ultrasonic wire bonding device, FIG. 2 is a schematic configuration diagram showing the principle of contact surface detection means of the ultrasonic wire bonding device according to the present invention, and FIGS. 3 and 4 are Figure 2 shows the detected voltage waveform based on the supplied output current from the ultrasonic oscillator of the device, Figure 3 is a waveform diagram before the contact surface of the capillary tip, Figure 4 is a waveform diagram when the capillary tip is in contact, and Figure 5 1 is a schematic configuration diagram of an ultrasonic wire bonding apparatus according to an embodiment of the present invention. 1... Vibrator, 2... Capillary chip, 4... Ultrasonic oscillator, 11... Pellet, 12... Fine metal wire, 12a...
・Bonding surface, 22...Detector, 23...
...Controller.

Claims (1)

[Claims] 1. A vibrator having a capillary tip attached to its tip, an ultrasonic transmitter that is electrically connected to the vibrator and applies an output voltage to generate ultrasonic vibrations, and the above-mentioned connection from the ultrasonic transmitter. The electrical element is inserted into the circuit and detected based on the output current, and the detected value before contacting the bonding surface of the capillary chip with the sequentially detected values are compared and the difference between the two is determined.
An ultrasonic wire bonding apparatus characterized by comprising a detector which outputs a detection signal when the temperature exceeds a predetermined value and detects the contact surface of the capillary chip. 2. The ultrasonic wire bonding apparatus according to claim 1, wherein the electric element has a voltage value proportional to the output current. 3. The ultrasonic wire bonding apparatus according to claim 1, wherein an output current value is taken as the electric element. 4. The ultrasonic wire bonding apparatus according to claim 1, wherein the electric element is a voltage waveform based on an output current.