JP3083643B2 - Ultrasonic power supply method for ultrasonic wire bonding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic power supply method for an ultrasonic wire bonding apparatus used for wire bonding of electronic equipment and the like.

[0002]

2. Description of the Related Art Ultrasonic wire bonding is widely used for wire bonding of electronic components such as integrated circuits. The bonding mechanism of the ultrasonic wire bonding method is a mechanism for bonding a wire to an electronic component or a wiring electrode, which is a material to be bonded, by applying an appropriate amount of ultrasonic waves for a necessary time using a bonding tool called a capillary. Of these, the intensity and application time of the ultrasonic vibration
By presetting the output and time limit of the ultrasonic oscillator, the required amount can be automatically and repeatedly applied for the required time. The timing of the application is linked to the vertical movement of the bonding tool, and the pressing of the wire to the electrode is also performed by the vertical movement of the bonding tool.

An example of the operation of a bonding tool called a capillary (hereinafter referred to as a capillary) will be described. In FIG. 3, in the vertical movement of the capillary, first, the capillary at the top level is lowered to the first search level, where the speed is adjusted for positioning the bonding position. Next, the capillary descends to the surface of the electrode of the electronic component to be wire-bonded, and a predetermined load is applied. At the same time, the ultrasonic vibration is applied and the capillary rises until after the first bonding. Next, the capillary moves over the electrodes of other wire-bonded electronic components and wirings and drops to the second search level. Here, for position adjustment, speed adjustment is performed, and then descend to the 2nd bonding position.
And a predetermined load and ultrasonic vibration are applied,
And climb to the top level. When the first and second bonding are completed in this way, the wire is cut by a pull-cut method or the like, and the capillary moves to the next wire bonding operation.

As described above, the ultrasonic wire bonding is performed by the above-described operation of the capillary. However, currently used ultrasonic wire bonders have limited bonding conditions such as ultrasonic power, load, tool speed, and temperature depending on the type of work. Have been. Once these bonding conditions are set, they are not changed unless there is a change in the type or the like on the work side. For these reasons, even if the below-described degradation of the capillary starts to occur, the condition is reviewed only when it affects the quality, so that the yield of bonding is inevitably reduced. In addition, there is a part where the change of the condition is performed while relying on the intuition of the person who performs the review, and individual differences appear.

[0005] The cause of the deterioration of the capillary will be described below. In FIG. 2, (A) of FIG. 2 shows a state in which the capillary is located at the second bonding position by the above operation. As is clear from the figure, a wire 2 made of gold or the like is bonded to a material 13 to be bonded at a part of the tip of the capillary 1. At the time of this bonding, the wire 2 is one-sided at the tip of the capillary 1, and the dust 3 of the gold wire forming the wire 2 adheres to the tip of the capillary 1. By repeating the operation, the dust 4 moves into the cylinder of the capillary 1 and adheres. As described above, due to the adhesion of the gold constituting the wire to the tip of the capillary and the adhesion of the scraps of the gold wire to the inside of the capillary tube, the capillary itself deteriorates according to the frequency of use. The deterioration of the capillary causes a reduction or deviation in the amount of transmission of the ultrasonic wave to the material 13 to be bonded, resulting in deterioration during bonding.

[0006]

SUMMARY OF THE INVENTION The present invention provides an ultrasonic bonding method capable of reducing a decrease in bonding quality due to deterioration of the bonding tool and improving a yield.

[0007]

SUMMARY OF THE INVENTION The present invention is characterized in that the bonding conditions are changed depending on the frequency of use of a bonding tool, and in particular, an ultrasonic oscillator driven by an ultrasonic oscillator, and an ultrasonic oscillator A bonding tool to which vibration is transmitted, wherein the ultrasonic power is increased according to the frequency of use of the bonding tool in an ultrasonic wire bonding apparatus for bonding a wire to a material to be bonded by vibration of the bonding tool. And Conditions for changing the ultrasonic power include the amount of power, the amount of bonding pressure, and the time.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of conditions for changing the bonding conditions according to the frequency of use will be described below. In order to increase the ultrasonic power, the power supplied to the ultrasonic transducer by the ultrasonic oscillator, which is a representative factor of the bonding conditions, is changed according to the frequency of use of the bonding tool. Here, the unit of the frequency of use of the bonding tool is a shot, which is the first bonding and the second bonding.
The operation of stretching the wire during bonding is one shot at a time. One shot usually has a wire length of about 1.0 to 2.0 mm, depending on the distance between the electrodes between the electronic components to be wire-bonded.

In the following example, the ultrasonic power is changed (increased) depending on the frequency of use of the bonding tool. If the power of the ultrasonic wave is expressed in bits, there is a slight difference between the types of the ultrasonic wire bonder.
When the output relation is adjusted to 5 W, 1.
95 mW.

Frequency of use 0 to 200,000 200,000 to 300,000 300,000 to 400,000, 400,000 to 450,000 Ultrasonic power 80 85 87 89 (bit) By recording these conditions in a RAM, floppy disk, or the like, Digital control makes it possible to automatically control the conditions of wire bonding according to the frequency of use of the bonding tool.

FIG. 1 is a block diagram for controlling the output power of the ultrasonic oscillator, and shows from the capillary to the main controller (CPU). In FIG. 1, 6
Is a main controller, 5 is an ultrasonic oscillator, 7 is an ultrasonic oscillator, 8 is a horn for transmitting ultrasonic vibration to the capillary 1, and 9 is a mounting bolt for attaching the capillary 1 to the transmission horn.

The power transmitted from the ultrasonic oscillator 5 to the capillary 1 varies depending on the quality of the capillary 1, the mounting bolt 9, the horn 8, the ultrasonic vibrator 7, and the adjustment. The degree of the change differs depending on the input impedance of the ultrasonic vibrator 7, and this impedance is obtained by measuring the output signal levels of the terminals 10, 11, and 12, and this impedance differs for each model.

Therefore, when using the ultrasonic bonder, the impedance is measured in advance and stored in the main controller 6, and the frequency of use of the capillary of the ultrasonic bonder is stored in the main controller 6 every time the ultrasonic bonder is used. I do. When the ultrasonic bonder is used, the output of the ultrasonic oscillator 5 is set by the main controller 6 according to the impedance and the frequency of use of the capillary, and the ultrasonic transducer is driven. The bit conversion operation for changing the ultrasonic output is performed by directly inputting a number from a keyboard in a program menu set on the wire bonder, or selecting several types of condition setting calculation formulas and inputting only variable values. It can be carried out.

[0014]

According to the present invention, it is possible to change the ultrasonic output in accordance with the frequency of use of the bonding tool and to set conditions before the occurrence of a bonding failure. Is improved. In addition, it is possible to save the trouble of reviewing the bonding conditions of the ultrasonic bonder.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of capillary deterioration.

FIG. 3 is an explanatory diagram of the operation of the capillary.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Capillary 2 Gold wire 3 and 4 Scrap of gold wire 5 Ultrasonic oscillator 6 Main controller

Claims (2)

(57) [Claims] An ultrasonic oscillator driven by an ultrasonic oscillator, and a bonding tool to which vibration of the ultrasonic oscillator is transmitted, wherein the vibration of the bonding tool bonds a wire to a material to be bonded. In the ultrasonic wire bonding apparatus, an ultrasonic output is controlled according to the frequency of use of the bonding tool. 2. The ultrasonic output supply method according to claim 1, wherein the ultrasonic output is increased in accordance with an increase in the use frequency of the bonding tool.