JPS61190953A - Wire bonder - Google Patents

Abstract

PURPOSE:To enable a bonding at the central position of a lead by mounting an arithmetic operation section computing the position of indication of optimum bonding in the actual lead to a control system. CONSTITUTION:A control system 2 has a recognition section 21, which recognizes an inner lead 18A and an electrode pad 19A for a semiconductor structure 17 form a signal from a TV camera 20 and outputs the central position of the structure 17 as a recognition data, a memory section 22, which previously memorizes the relative quantities of deviation of the positions of indication of optimum bonding (positions where the center of a capillary must be positioned) to the central position of various inner leads and electrode pads as data, and an arithmetic operation section 23 determining the absolute positions of indication of optimum bonding of the inner lead 18A and the electrode pad 19A in the present semiconductor structure 17 by outputs from the recognition section 21 and the deviation data memorized to the memory section 22. Accordingly, a wire bonder can be automated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a wire bonder, and particularly to a wire bonder that can perform wire bonding to leads with high reliability.

[Foreground technology]

Wire bonding is performed to electrically connect the electrode pads of semiconductor pellets fixed on the lead frame or package base of a semiconductor device to the external leads of the lead frame or package base. Wire bonders are often configured as automatic wire bonders that automatically recognize electrode pads and leads and then connect wires to the recognized positions. For example, examples that describe such techniques include Kogyo Kenkyukai, Electronic Materials, November 1983 issue, special edition, November 15, 1983, P, 140-145.

Usually, the recognition positions of the electrode pads and leads are set at their respective center positions, and the bonding tool is positioned here to perform wire bonding.

By the way, in a wire bonder that performs the first bonding to an electrode pad using the so-called nail head bonding method, in which a ball is formed at the tip of the wire and the capillary crushes the ball while performing thermocompression bonding, the center of the capillary and the center of bonding are always aligned. Therefore, even if the above-described recognition method is used as is, the recognition position and the wire bonding position always match, and good bonding to the electrode pad can be performed.

However, even with this wire bonder, as shown in FIGS. 4 and 5, during the second bonding in which the wire 31 is pressed onto the lead 32 while being crushed on one side of the capillary 30, the actual bonding position Bx is
The lead recognition position (lead center position) C
It becomes impossible to bond correctly on x. In particular, the effect of this phenomenon becomes greater as the deviation between the extending direction of the leads 32 and the extending direction of the wire 31 (plane This is a cause of deterioration in the reliability of wire bonding.

For this reason, conventional wire bonders of this type have low reliability, especially when bonding wires to multi-pin semiconductor devices. There are also problems in that the work is complicated, as it has to be programmed, and it lacks versatility.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a wire bonder that can always bond a wire to a preferred position on a lead and improve the reliability of a semiconductor device.゛The above and other objects and novel features of the present invention are as follows:
It will become clear from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

In other words, there is a recognition unit that recognizes the center position of the lead, a storage unit that stores the amount of deviation of the optimum bonding instruction position with respect to this center position, and an optimum bonding instruction for the actual lead based on the respective outputs of these recognition unit and storage unit. By providing a calculation unit that calculates the position in the control system of the wire bonder, it is possible to easily determine the optimal bonding instruction position that is offset from the center position of the lead by the amount of deviation determined in advance by self-teaching and stored in the storage unit. This enables good wire bonding and improves the reliability of the semiconductor device.

〔Example〕

FIG. 1 is an overall configuration diagram of an embodiment of a wire bonder in which the present invention is applied to nail head bonding using gold wire. In the figure, 1 is the wire bonder main body, and 2 is a control system.

The wire bonder main body 1 supports a bonding arm 12 that is vertically swingable on a bonding head 11 mounted on an XY table 10, and has a capillary 13 fixed to the tip thereof. As is well known, this capillary 13 has a conical tip end, and the tip of a gold wire 14 as a bonding wire wound around a pulley 15 supported on the upper part of the bonding rod 11 is inserted into its hollow hole. ing. Further, it goes without saying that the bonding arm 12 is swung up and down by a cam mechanism (not shown), and that the capillary 13 is moved up and down along with this oscillation.

On the other hand, a bonding stage 16 is arranged below the capillary 13, and a semiconductor structure 17 to be wire-bonded is placed thereon. In this example, in this semiconductor structure 17, a semiconductor pellet 19 is fixed on a lead frame 18, and the gold wire 14 is connected between an inner lead 18A of the lead frame 18 and an electrode pad 19A of the semiconductor pellet 19.

Further, a TV camera 20 is supported by the bonding head 1 above the capillary 13, and can image the surface of the semiconductor structure 17 on the bonding stage 16.

On the other hand, the control system 2 controls the inner lead 18A of the semiconductor structure 17 and the electrode pad 19 from the signal from the TV camera 20.
A recognition unit 21 recognizes A using a known pattern recognition method and outputs the center position as recognition data, and a recognition unit 21 that recognizes the center position of A by a known pattern recognition method and outputs the center position as recognition data, and determines in advance the optimum bonding instruction position (the position where the center of the capillary should be located) with respect to the center position of various inner leads and electrode pads. ), and the output of the recognition section 21 and the bias data stored in the storage section 22 are used to determine the current inner lead 18A and electrode pad in the semiconductor structure 17. The calculation unit 23 determines the absolute optimum bonding instruction position of 19A. The storage unit 22 is provided with a self-teaching unit 25 that performs predetermined calculations based on external design data 24 and the respective outputs of the recognition unit 21, from which the bias data described above is taken in and stored. It is supposed to be done. Further, the calculation unit 23 is connected to a controller 26 that controls the XY table 0, and the capillary 13
can be set to the optimum bonding instruction position.

It goes without saying that each part of the control system 2 can be configured to be centrally controlled by a computer (not shown), and numeral 27 in FIG.

Next, a wire bonding operation using the wire bonder having the above configuration will be explained.

First, the semiconductor structure 17 to be wire-bonded on the bonding stage 16 is imaged with the TV camera 20, each inner lead 18A and electrode pad 19A is displayed on the monitor 27, and a marker is set to determine the optimal bonding of each inner lead 18A and electrode pad 19A. Align with the indicated position. Incidentally, in each electrode pad 19A, the optimum bonding instruction position coincides with the center position, so no problem occurs, and therefore, the case of the inner lead 18A will be explained here.

That is, in the case of the inner lead 18A', as shown in FIGS. 2 and 3, the direction in which the inner lead 18A extends,
Depending on the stretching direction of the gold wire 14, the optimum position for the center of the capillary 13, that is, the optimum bonding instruction position f3-n, is the center position C of each inner lead 18A.
biased against n. Therefore, mark alignment to this optimum bonding instruction position is performed for all inner leads by using the design data 24 or the like.

On the other hand, by recognizing each inner lead 18A, the recognition unit 21 recognizes the center position of each lead, in other words, the position where the gold wire 14 is actually to be bonded.

Then, the self-teaching unit 25 uses the position recognition data of the inner leads 18A of the recognition unit 21, that is, the center position Cn of each inner lead 18A and the optimal bonding instruction position Bn aligned by the marker, to determine the position of both in the XY direction. The amount of deviation (Xn, Yn) is automatically calculated and stored in the storage unit 22 as deviation data. This calculation is performed for all of the plurality of inner leads, and thereby the relative deviation amount of the optimum bonding instruction position with respect to the center position is stored for all of the inner leads 18A in the semiconductor structure 17 of this structure. That is, self-teaching is completed.

Therefore, when a series of semiconductor structures 17 to be wire bonded are sequentially moved onto the bonding stage 16, each semiconductor structure 17 is imaged by the TV camera 20 each time, and the recognition unit 21 identifies each inner lead 18A. The center position is recognized. This center position is sent to the calculation unit 23 as recognition data.

Then, the calculation unit 23 fetches the bias data corresponding to each inner lead 18A from the storage unit 22, and calculates the absolute optimal bonding instruction for each inner lead 18A based on the relative position of both data and the center position. Calculate the position. Then, by controlling the controller 26, the position of the XY table 10 is controlled and the capillary 1 is
3 is set at this optimum bonding instruction position, and wire bonding to the inner lead 18A is performed.

In this way, if the capillary 13 is positioned and wire bonding is performed, gold, v11 and
4 is thermocompression bonded to the inner lead 18A in an example of the direction in which the gold wire is stretched at the tip of the capillary 13, and this position B
a is deviated from the center position Ca of the capillary 13, but this amount of deviation is equal to the previously memorized amount of deviation (X n
s Y n ), therefore gold, 11111
4 is bonded to the center position Ca of the inner lead 18A, which is offset by this amount from the optimum bonding instruction position.

By doing this, if you do self-teaching first,
Optimal wire bonding can be automatically performed for all the inner leads 18A of a large number of semiconductor structures 17 having the same configuration thereafter.

〔effect〕

(1) The control system of the wire bonder includes a recognition unit that recognizes the center position of the lead, a storage unit that stores the amount of deviation of the optimal bonding instruction position with respect to this center position, and a control system that uses the It is equipped with a calculation unit that calculates the optimal bonding instruction position for the actual lead, so once the lead is recognized, the capillary can be set to the optimal position for all leads, and bonding can be performed at the center position of the lead. Highly reliable wire bonding can be achieved.

(2) Since it has a self-teaching section that calculates the amount of deviation of the optimum bonding instruction position with respect to the center position and stores it in the storage section, the amount of deviation can be set by the wire bonder itself, and the wire bonder can be automated. Can be done.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, the control system recognition section, storage section, and calculation section do not need to be configured independently; instead, the entire control system can be configured using a computer, and the same functions as each section can be programmed using software technology. You can.

C Field of Application] The above explanation has mainly been about the case where the invention made by the present inventor is applied to a wire bonder using gold wire, which is the field of application that formed the background of the invention, but it is not limited thereto. It can also be applied to nail head bonding type wire bonders using aluminum wires and copper wires other than wires.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of the wire bonder of the present invention, FIG. 2 is an enlarged plan view of a portion of the electrode pads and leads of the semiconductor structure, FIG. 3 is an enlarged plan view of the leads, and FIGS. 4 and 5. FIG. 4 is a cross-sectional view and FIG. 5 is a plan view for explaining the bonding position shift. 1... Wire bonder body, 2... Control system, 10...
・XY table, 11...bonding head, 12
...Bonding arm, 13...Capillary, 1
4... Gold wire, 16... Bonding stage, 17
...Semiconductor structure, 18...Lead frame, 18A
... Inner lead, 19 ... Semiconductor pellet, 19
A... Electrode pad, 20... TV camera, 21...
- Recognition unit, 22... Storage unit, 23... Calculation unit, 24
...Design data, 25...Self-teaching section, 2
6... Controller. Figure 2 Figure 1a Figure 3

Claims (1)

[Claims] 1. A wire bonder equipped with a control system that recognizes the leads of a semiconductor structure placed on a bonding stage, positions a capillary of a wire bonder main body on the leads, and performs wire bonding. The control system includes a recognition unit that recognizes the center position of the lead, a storage unit that stores the amount of deviation of the optimal bonding instruction position at which the capillary should be located with respect to this center position, and each of the recognition unit and storage unit. A wire bonder comprising: an arithmetic unit capable of calculating an optimal bonding instruction position to a lead of a semiconductor structure to be currently wire-bonded based on an output and setting a capillary at this position. 2. The memory section has a self-teaching section, so that the amount of deviation can be determined from the lead center position recognized with respect to the first semiconductor structure and the optimal bonding instruction position set in advance for this lead. A wire bonder according to claim 1, comprising: