JPS61105852A - Wire bonder - Google Patents

Abstract

PURPOSE:To enable to perform a high-speed bonding by a method wherein a wire bonding operation is started based on the signal indicating that the terminal to be used for wire bonding comes in contact with the surface where the wire bonding is performed. CONSTITUTION:When the length of wire bonding surface varies in the amount of height of H1, H2 or H3 for the reference surface L1 when a wedge 1 comes down by the action of a motor circuit 17, the wedge 1 comes in contact with the surface of wire bonding at points t1, t2 and t3. At that time, a detection signal is outputted to a timer 15 from a detector 12, and an ultrasonic wave vibrator 4 is started oscillation after the lapse of time Ta necessary to attenuate the vibration of the wedge 1 by the timer 15, and an ultrasonic wave bonding is started. A signal is outputted to the timer 16 from the vibrator 4 at the same time when the wire bonding is finished, a motor 11 is inversely rotated at a high speed, and the wedge is moved upward and returned to its original position through the intermediate of a cam 9. Accordingly, a bonding work can be performed at a high speed without having a waiting time even when irregularity in size is generated on a semiconductor device.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wire bonder for semiconductor devices, and more particularly to a wire bonder that controls the bonding action according to dimensional variations in the wire bonding portion of the semiconductor device and increases the bonding speed. It is.

There are various wire bonding methods for semiconductor devices. For example, the ultrasonic wire bonding method uses ultrasonic energy to vibrate the bonding wire against the bonded object while exposing the fresh surfaces of each other, resulting in plastic deformation. It performs solid phase bonding. As shown in FIG. 1, a wire bonder that performs this type of wire bonding has a wedge 1, which is a bonding terminal, at the tip of a horn 3 connected to an ultrasonic transducer.
A configuration is proposed in which the wedge 1 is moved downward into contact with the wire bonding surface or separated upward by swinging the horn 3 up and down by a cam 9 rotated by a drive motor 11. 8 is an XY table for moving the wedge 1 back and forth, left and right; 2 is an aluminum wire that is a bonding wire guided to the tip of the wedge 1; and 20 is an object to be bonded (semiconductor device) supported on a support base 30.

Therefore, the wire bonding method using this type of device is designed so that the shape of the cam 9 or the rotational speed of the cam is controlled so that the wedge 1 has a vertical movement profile as shown by the solid line in FIG. The wedge 1 is first rapidly and then slowly lowered from the top dead center position to bring it into contact with the wire bonding surface, while at the same time, when a predetermined time has elapsed, the ultrasonic transducer is activated to Perform sonic wire bonding, and after completion of the sonic wire bonding, run 4 with a program that quickly returns wedge 1 to upward motion with reduced residual vibration.
Wow. Note that this bonding is performed alternately on the pellet side and the lead side. Further, the reason why the wedge is moved slowly downward is to prevent deterioration of wire bondability and damage to the wedge and the wire bonding surface caused by the wedge contacting the wire bonding surface with impact.

Regarding the technology that speeds up the downward movement of the wedge in this way (
・It is 7[\sa)9te(・ru) in Japanese Patent Application Laid-Open No. 55-11736.

(2) However, in a normal semiconductor device, for example, as shown in the example of a ceramic package shown in FIG. There are large variations in the component accuracy of the leads 25 attached to the ceramic package body 23 using the low melting point glass 24, and furthermore, there are large variations in the depth of embedding the leads 25 into the low melting point glass 24.
For this reason, variations occur in the top surface height Ha of the pellet 21, which is the wire bonding surface, and the top surface height Hb of the leads 25 (both with respect to the bottom surface of the ceramic package body 23).

Therefore, if the wire bonding surface varies higher than the reference height and there are ΔHa and ΔHb, the wedge
The reference contact time t is shown in phantom in the figure. The wire bonding surface will be contacted at a time ty some time earlier than ty. Therefore, the wedge remains in static contact with the wire bonding surface until ultrasonic waves are generated, and after the bonding by ultrasonic vibration is completed, it is returned to the upward movement as in the conventional method. As a result, the waiting time tx, from when the wedge comes into contact with the wire bonding surface until the ultrasonic wire bonding is started, becomes longer than necessary, which is one of the reasons why the wire bonding operation time becomes longer. .

Another object of the present invention is to provide a wire bonding method and a wire bonder that can change the wire bonding program according to the dimensional variations of semiconductor devices, thereby eliminating wasted time and speeding up bonding. It is about providing.

In order to achieve the above object, the method of the present invention detects when the bonding terminal reaches the wire bonding surface and makes contact, and immediately performs the bonding action after a predetermined time has elapsed based on the time of this contact. It is characterized by one feature that allows the user to perform the following steps. The device of the present invention also includes a detector for detecting that the bonding terminal has contacted the wire bonding surface, and a control circuit that can start the wire bonding action after a predetermined time based on a signal from the detector. This is a characteristic feature.

The present invention will be explained below using an ultrasonic wire bonding method as an example.

First, the ultrasonic wire bonder of this embodiment will be explained, and then its operation and wire bonding method will be explained.

FIG. 4 is an overall configuration diagram of the ultrasonic wire bonder of this embodiment. In the figure, 1 is a wedge that is a bonding terminal, and an aluminum wire 2 that is a bonding wire is guided to the tip of the wedge 1. Reference numeral 3 designates a horn to which an ultrasonic vibrator 4 is connected, which is pivotally supported on a base 6 together with an integrally formed horn support 5, so that it can swing up and down at points 1 to 1 about its pivot point 7. It has become. 8 is to horizontally move the wedge back and forth and left and right via this base 6.XY
It is a table, and the wedges 1 are successively positioned facing the wire bonding surfaces on the pellets and leads by a control mechanism (not shown). 9 is rotated by a drive motor 1 through a cam tarry and a belt means 10 which are in sliding contact with one end of the horn support 5, and swing the horn support 5 and the horn 3 up and down according to changes in the rotational speed thereof;
Wedge] & move up and down. The cam 9 has a linear cam diagram, and the drive motor 11 is capable of speed adjustment and forward and reverse rotation. Further, 20 is a semiconductor device to be bonded, and 30 is a support stand for supporting this.

12 indicates that the wedge 1 is in contact with the wire bonding surface 1. The detector is electrically connected to a lever 13 electrically insulated from the horn support 5, and when the wedge 1 descends and contacts the wire bonding surface, the lever 13 is grounded. Move away from cam 9 and move lever 13'
By increasing the li pressure, it is detected that the wedge 1 has come into contact with the wire bonding surface.

Further, 14 is a control circuit that causes the ultrasonic vibrator 4 to oscillate based on the contact detection signal from the detector 12, and conversely rotates the drive motor 11 in the reverse direction based on the end of oscillation of the ultrasonic vibrator 4. . That is, this control circuit 14 includes a timer 15 that sends a starting signal to the ultrasonic transducer 4 at a preset time every time it receives a signal from the detector 12, and a counter that the ultrasonic transducer 4 has built-in. A timer 16 receives a signal sent back from the ultrasonic transducer 4 immediately after it oscillates for a predetermined period of time due to the action of
It has The motor circuit 17 has a function of reversing the drive motor 1 so that the wedge 1 is returned to the road dead center position when the signal from the timer 16 is input. The drive motor 11 and the cam 9 are provided with an encoder that detects the rotation angle and a tacho generator (both not shown) that detects the rotation speed, and these work together with the motor circuit 17 to control the rotation of the wedge 1. The vertical motion profile is illustrated in FIG. 2, for example. This is because the characteristics are set to 1.

Next, the method of the present invention will be explained together with the operation of the wire bonder having the above structure.

As shown in FIG. 5, when the wedge moves downward rapidly and then slowly due to the action of the motor circuit 17, the height of the wire bonding surface at that time is higher than the reference surface L1. Sa H, In, or T4. If the variation is too high, the wedge will contact the wire bonding surface at each point 'I + '2 r 13. Therefore, at this time, a detection signal is output from the detector 12 to the timer 15, and the timer 15 immediately starts the ultrasonic vibrator 4 to oscillate after a predetermined time ta has elapsed from that time, and starts ultrasonic bonding. In other words, as is clear from Figure 5,
The sooner the wedges come into contact, the sooner ultrasonic bonding will begin. This eliminates the conventional waiting time tx shown in FIG. 2, making it possible to speed up bonding by that much.

Note that the time t8 set in the timer 15 is the time required to attenuate the one-stroke movement that occurs when the wedge comes into contact with the wire bonding surface, and is set in order to avoid adversely affecting the bonding action immediately after. provided.

At step 12, a signal is output from the vibrator 4 to the timer 16 at the same time as the wire bonding action ends, and after an extremely short time tb necessary for the residual vibration of the wedge to disappear,
The timer 16 outputs a signal to the motor circuit 17, and the motor 1
] is reversely rotated at high speed, and the wedge upper movement is later tightened via the cam 9. When the wedge is restored, the above-described bonding process is repeated again by the cooperation of the encoder and motor circuit 17.

Therefore, if the wire bonding surface is on the higher side, the time required for bonding on the reference surface is tcl l tC2 + tc3 as shown in FIG.
It can be shortened only.

Here, if the collision vibration when the wedge contacts the wire bonding surface does not affect the bonding action, the predetermined time in the timer 15 can be made extremely short, and in some cases, the set time can be set to 0. . This is the timer 16 at the end of the bonding action.
The same applies to

Furthermore, although the above embodiments have exemplified ultrasonic bonding,
If the ultrasonic vibration effect is replaced with a pressure bonding effect, it can be applied to other types of bonding such as nail hend bonding and wedge bonding.

As described above, according to the wire bonding method of the present invention, when it is detected that the bonding terminal has contacted the wire bonding surface, the bonding action is immediately performed after a predetermined period of time has elapsed, and the wire bonder of the present invention has this action. Therefore, even if there are dimensional variations in the semiconductor device, the contact edge of the bonding terminal with the wire bonding surface will be photon bonded within a certain period of time, which is different from conventional methods. By eliminating the waiting time 12, the speed of bonding can be increased accordingly. Furthermore, since the time from the contact of the bonding terminal to the start of the bonding action is constant regardless of dimensional variations, stable bonding can be performed and bonding reliability can be improved.

[Brief explanation of the drawing]

Fig. 1 is a schematic side view of a wire bonder using the ultrasonic bonding method, Fig. 2 is a diagram showing the vertical movement profile of the wedge in this wire bonding method, and Fig. 3 explains dimensional variations in semiconductor devices. A cross-sectional view, FIG. 4 is an overall configuration diagram schematically showing an embodiment of the wire bonder of the present invention, and FIG. 5 is a diagram showing the vertical movement profile of the wedge of the wire bonder according to the present invention. l... Wedge, 2... Aluminum wire, 3...
Horn, 4... Ultrasonic oscillator, 8... XY table, 9... Cam, 11... Drive motor, 12... Detector, 14... Control circuit, 15.16...・Timer,
17... Motor circuit, 20... Semiconductor device, 21.
... Pellet, 23 ... Ceramic package body,
25...leat.

Claims (1)

[Claims] 1. A wire bonder having a wire bonding terminal that moves between a die-bonded pellet and each wire bonding surface of an external conductive lead and contacts the wire bonding surface to perform wire bonding. , a detector that detects that the wire bonding terminal has contacted the wire bonding surface;
A wire bonder comprising: a control circuit that starts a wire bonding action after a predetermined time based on at least a signal from the detector. 2. The wire bonder according to claim 1, wherein the wire bonding terminal is a wedge, and the wire bonding action is an ultrasonic bonding action accompanying oscillation of an ultrasonic vibrator.