JPS61260644A - Bonding device - Google Patents

Abstract

PURPOSE:To prevent false measurement by a method wherein a circuit, which detects a bleeder resistor voltage originating in a discharge, and another circuit, which compares a detected discharge current with a detected discharge voltage for the yield of signals indicating the detection of a discharge, are provided. CONSTITUTION:In the presence of a normal spark discharge, a discharge current detecting circuit 2 and bleeder resistor voltage detecting circuit 3 involving the discharge voltage detect a current and voltage, respectively. in the absence of a spark discharge, the circuit 2 detects no current while the circuit 3, with the whole voltage imposed upon a bleeder resistor, detects a voltage. In the presence of a short circuit between the entire wiring and a spark electrode, the circuit 2 detects a current while the circuit 3 detects no voltage because there is no voltage across the bleeder resistor due to the voltage drop attributable to the short circuit. In a device of this design, real conditions involving a discharge may be correctly determined because the output of a discharge current detecting circuit is compared with that of a discharge voltage detecting circuit, which contributes to the prevention of false measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a wire g7 bonding device using spark discharge, and more particularly to a bonding device having a circuit for detecting a spark discharge state.

(Prior Art) In the manufacture of semiconductor integrated circuit (IC) parts, the wire ending process for connecting the bonding node part of the IC chip and the pin terminal of the lead frame with a metal lead wire, for example, a gold wire, is speeded up. This is extremely important for mass production of parts.

For this reason, automatic wire ending devices have been widely adopted in IC manufacturing lines in recent years. In this wire-dending process, the thermocompression bonding area between the gold wire and the bonding/grading area is large, and the mechanical impact on the bonding/grading area is reduced to prevent cracks from occurring at the 871 part. Money to do it? - Formation of a system is essential. As a method for forming this gold goal, a method using electrical spark discharge between a gold wire and a spark electrode is currently widely practiced.

The bonding cycle of such automatic wire bonding equipment consists of the following three main steps.

(1) Lower the capillary and thermocompress the pad and gold ball. (Thermocompression bonding process) (2) Raise the capillary and send out a predetermined length of gold wire from the tip of the capillary. (Gold wire delivery process) (3) A spark electrode is placed at the tip of the gold wire, and a predetermined gold pole is formed by spark discharge. (Gold Ball Formation Step) In the conventional automatic wire bonding apparatus, the presence or absence of gold ball formation was detected by the presence or absence of a discharge current. That is, if the amount of gold wire delivered is appropriate in the gold wire delivery process, spark discharge will occur in the gold pole forming process, and a signal at the "o" level will be detected by this emitted current. When the amount is small, the gap between the spark electrode 1 and the tip of the gold wire becomes large, and spark discharge does not occur, and no discharge current flows, so that an "L" level signal is detected. Therefore, if the "11" level was detected (t14), the binding cycle was continued, and if the "1" level was detected, the binding cycle was stopped.

(Problem to be Solved by the Invention) However, in the gold wire delivery process, if the amount of gold and glands sent out is too large and short-circuits with the spark electrode, even though spark discharge is not performed, /7 A current flows. In other words, even though gold d-~le has not been formed.”
II'' level signal is detected.

In this state, the bonding device
If the level signal is not detected, the sensor ink cycle will continue, so the tip of the capillary of the bonding device will not directly touch the Rad section. In other words, there is a drawback that a TO with poor bonding is produced.

(Means for Solving the Problem) Therefore, in addition to the circuit for detecting the discharge current, the bonding apparatus of the present invention includes a circuit for detecting the partial resistance voltage of the discharge voltage, and a circuit for detecting the discharge current detection signal and the discharge voltage. A circuit that compares the discharge detection signal with the discharge detection signal and outputs a discharge detection signal is provided.

(Operation) When a normal spark discharge occurs, both the circuit for detecting the discharge current and the circuit for detecting the partial resistance voltage of the discharge voltage detect it.

If spark discharge does not occur, the circuit that detects the discharge current does not detect current, but the circuit that detects the divided resistor voltage of the discharge voltage detects the voltage because the entire voltage is applied to the divided resistor.

If the gold wire is short-circuited with the spark electrode, the circuit that detects the discharge current will detect the current, but the circuit that detects the voltage-dividing resistor of the discharge voltage will detect that almost no voltage is applied to the voltage-dividing resistor due to the voltage drop due to the short circuit. No voltage detected.

Here, the correct discharge state is detected by comparing the outputs of the circuit for detecting the sheet weight current and the circuit for detecting the discharge voltage.

(Embodiment) FIG. 1 is a diagram showing an embodiment of the present invention, which includes a DC high voltage generation circuit 1, a discharge current detection circuit 2, a discharge voltage division resistance voltage detection circuit 3, and a discharge signal generation circuit 4. The circuit section is constructed from the following. The direct current high voltage generation circuit 1
This is a circuit that actually performs spark discharge using the high voltage generated in the circuit. The spark discharge circuit 5 is composed of a spark electrode 6, a wire clamp 7, and a gold wire 8. Gold wire 8 is
The wire is sent out vertically from the gold wire spool 9 and guided through the gap between the wire clampers 7 and into the needle hole of the capillary 10. The capillary 10 is driven in the vertical direction together with the bonding arm 11. Cut wire clamper'P
7 temporally flanges the gold wire 8, and the spark electrode 6 is rotated horizontally by an angle θ (about 60° here) and placed directly below the capillary 10. At this time, the distance t1 between the tip of the capillary 10 and the spark electrode 6 and the distance t2 between the tip of the gold wire 8 and the spark electrode 6 are set values (in this example, t
, = 1 to 2 reduction, t2 = 0.3 to 0.5 order).

The DC high voltage generation circuit 1 includes a high frequency high voltage power supply 12 and a switch f.
-13, diode 14, diode 15, capacitor 16, capacitor 17, protection resistor 18 in case discharge occurs in spark discharge circuit 5, protection tI (resistor 19) in case discharge does not occur in spark discharge circuit 5. Ru.

In the discharge current detection circuit 2, a transistor 21 is operated to switch using a voltage that drops across a resistor 20 due to the discharge current, and the amplified waveform is shaped by an inverter 22 to obtain a discharge current signal.

In the discharge voltage dividing resistor voltage detection circuit 3, there is a sufficiently large (here 30 MQ) dividing resistor 23 and a dividing resistor 24 (here 150 Ω) arranged in parallel between the spark electrode 6 and the gold wire 8. ), the voltage applied to the voltage dividing resistor 24 is waveform-shaped by the C-MOS level converter 25 having a large input impedance to obtain a discharge voltage signal.

The discharge signal generation circuit 4 is constituted by a negative input AND logic circuit 26, and outputs a discharge signal based on the logical product of the discharge current signal and the discharge voltage signal.

Next, the operation according to the embodiment of the present invention will be explained with reference to the timing diagram of FIG. In Fig. 2, (1) shows that when a good discharge is obtained between the spark electrode 6 and the gold wire 8, (II)
In (g), the amount of gold #j18 sent out was too small and no discharge occurred; in (g), the amount of gold wire 8 sent out was too large, and the gold wire 8
This is a case where the spark electrode 6 and the spark electrode 6 are short-circuited.

First, after the silver electrode 6 is rotated by an angle θ (approximately 60° in this case) from the true point F of the capillary 10, the capillary 10 integrated with the bonding arm 11 is lowered to perform a bonding operation. Thereafter, the capillary 10 rises, and the spindle current WL6 rotates again by the angle θ and is placed directly below the capillary 10. At this time, the gold wire 8 has a specified length A3 (13=t,
−t2=o, s~1. ．． 7n+m), and the wire clamp 7 clamps the gold wire 8. For this reason, the gold wire 8 is connected to the ground line through the entire wire clamp 7.

Next, the timing signal generation circuit 27 generates a timing signal (
A) is output, the switch 13 switches 'r+(this actual cooling 1
], a closed rectifier circuit is formed for 5 to 15 milliseconds), and a DC high voltage is applied between the spark electrode 6 and the gold wire 8.

Here, if the gap t2 between the strip electrode 6 and the gold wire 8 is appropriate, spark discharge will occur, melting the tip of the gold wire 8, and forming the gold pole 8a. In such a good discharge state, the discharge current flowing out from the positive electrode of the capacitor 16 will flow through the protective resistor 18, the spark electrode 6, the aerial gear,
It flows into the ground line through the gold wire feather, and further flows into the negative electrode of the capacitor 7 through the resistor 20. At this time, at the resistor 20, due to the voltage drop due to the discharge current, "l
," level (-2.5V) is obtained (Fig. 2 (Ii) - (+)). This signal is transferred to the transistor 21.
By performing switching operation in addition to the base of , and further waveform shaping by the inverter 22, a discharge current signal of "L" level is obtained (FIG. 2(C)-(+)).

1, the divided voltage (5V) of the voltage excluding the voltage drop due to the discharge current is applied to the voltage dividing resistor 24 (-(1) in Fig. 2). This waveform has a very small current, so if you shape the waveform with the C-MOS level converter 25, which has a large input impedance, the signal will not disappear.
A discharge voltage signal of L” level is obtained (see Fig. 2 (E
) −(1) ).

When the discharge current signal and the discharge voltage signal are input to the negative input AND logic circuit 26, a discharge detection signal of 11'' level is output (FIG. 2(F)-(1)).

Next, if the gap t3 between the screen electrode 6 and the gold wire 8 is large and no screen discharge occurs, the capacitor 16
Since the current flowing from the positive terminal of the capacitor 17 flows through the protective resistor 19 to the negative terminal of the capacitor 17, the signal at the resistor 20 does not change (Fig. 2 (H) to (II)).

In other words, the discharge current signal remains at the 'H' level and does not change (Fig. 2 (0) - (II)).On the other hand, the high voltage of the DC high voltage generation circuit 1 is connected to the voltage dividing resistor 23 without any voltage drop. Since it is applied to the voltage dividing resistor 24, the waveform of the voltage dividing resistor 24 becomes a "H" level signal of about 11V (as shown in Figure 2).
-([1)). When this waveform is shaped by the C-MOS level converter 25, a discharge voltage signal of "L'" level is obtained (FIGS. 2(E)-(II)).

However, since the discharge current signal is at the 'II' level, the output of the negative input AND logic circuit remains at the 'L' level and does not change (FIGS. 2(F)-(II)).

Next, if the amount of gold wire 8 sent out is too large and short-circuits with the spark electrode 6, the current passing through the resistor 20 will increase, resulting in a voltage drop and a ``L'' level (-3V) signal will be output. (Figure 2(B)-([1)).

When this signal causes the transistor 21 to perform a switching operation and the inverter 22 further shapes the waveform, II l,
A discharge current signal of +Level is obtained (Figure 2 (C) - (
To)).

On the other hand, due to the voltage drop due to the short circuit current, almost no voltage is applied to the voltage dividing resistor 24 ((9)-(g) in FIG. 2). In other words, the discharge voltage signal is at "H" level! , it doesn't change.

Therefore, the output of the negative input AND logic circuit remains at the "'L" level and does not change (FIG. 2(F)-GID').

As explained above, if the discharge detection circuit according to the present invention is used, the "II" level signal is output only when a good discharge is obtained, and the "L" level signal is output when a gold goal cannot be achieved.
″It is possible to output a level signal.

If the 11-signal generating circuit 28 is connected to the negative input AND logic circuit, the bonding cycle can be advanced if the discharge is good, and the bonding cycle can be stopped if the discharge condition is bad.

(Effects of the Invention) As explained above, according to the bonding device of the present invention, the dending cycle is continued only when a normal snow discharge is being performed, and a single discharge is not performed. The bonding cycle can be stopped if the wire is not present or a short circuit occurs due to the gold wire.
It is possible to completely prevent the "empty air" accident that causes C to be manufactured.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a timing diagram of each signal in FIG. 1. DESCRIPTION OF SYMBOLS 1... DC voltage generation circuit, 2... Discharge current detection circuit, 3... Discharge voltage division resistance voltage detection circuit, 4...
Discharge signal generation circuit, 5... Spark discharge section, 28...
Prohibition signal generation circuit. Patent applicant: Oki Electric Industry Co., Ltd. Miyazaki Oki Electric Co., Ltd.

Claims (1)

[Claims] A spark discharge section that forms gold balls by spark discharge and performs bonding, a power supply section that supplies voltage to the spark discharge section, and a current supplied from the power supply section to the spark discharge section. a discharge current detection circuit for detecting a discharge current; a discharge voltage division resistance voltage detection circuit for detecting a voltage division resistance voltage of the voltage supplied from the power supply section to the spark discharge section; and a division resistance voltage detection circuit for the discharge voltage. A bonding device comprising: a discharge signal generation circuit that generates a discharge signal by comparing an output with the discharge current detection circuit; and an inhibition signal generation circuit that transmits a bonding inhibition signal to the spark discharge section based on the discharge signal.