JPS5923418Y2 - automatic wire bonding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an automatic wire pointing device for wire bonding between a semiconductor chip and lead terminals.

In semiconductor devices such as light emitting diodes, attempts have been made to fully automate wire punching operations, and various devices have been developed and put into practical use.

This type of device is equipped with a pattern recognition device to automatically determine the punching position, and the relationship between the recognized electrode position information and the capillary installation position is determined through arithmetic processing, and the relationship between the capillary and the semiconductor chip is calculated. The relative movement amount is set and wire bonding to the appropriate position is performed.

In the conventional apparatus described above, the positional relationship for bonding between the capillary and the semiconductor chip is determined based on the recognized positional information by moving the XY table on which the capillary is attached.

In order to prevent the capillary from colliding with the frame holding stand of peripheral equipment during movement and being damaged, the XY table mentioned above is equipped with a limiter consisting of a microswitch etc. in the drive system of the XY table to prevent the capillary from colliding with the frame holding stand of peripheral equipment during movement. Measures are taken to stop the bonding operation if the capillary protrudes.

In this way, a limiter is necessary to restrict the movement range of the XY table, but when considering the movement of the XY table,
There is a relatively small range of movement that is performed during wire bonding, which is the original purpose, and a large range of movement that is performed during repair inspections and various adjustments.For the latter large movement range, a limiter using a micro switch is used. It can be fully accommodated.

However, there is a problem in that this limiter cannot cope with the former small movement range.

In other words, the limiter described above is necessary to prevent stress on the motor when the XY table comes off the support, but this type of limiter is usually inserted into the same power circuit as peripheral equipment such as the motor. peripheral devices.
The capillary mounted on the XY table may protrude out of the safe range during punching work, which can not only damage the tip of the capillary, but also cause damage to the tip of the capillary. ,
There was also a problem with wire supply, which caused bonding failures.

The present invention eliminates the drawbacks of the conventional device described above and adds a simple configuration to prevent damage to the device and ensure safe operation, and particularly to ensure safety during the first punching process for punching a wire onto a semiconductor chip.

Next, the present invention will be explained in detail using the drawings.

In the figure, 1 is a lead frame formed by punching a metal plate in a repeating pattern. For example, a lead terminal 1a and a lead terminal 1b are provided as a set, and a semiconductor chip 2 is mounted on the top of one lead terminal 1a. Equipped with
The automatic wire bonding apparatus according to the present invention stretches a wire between the lead terminal 1b and the other lead terminal 1b to establish an electrical connection.

The lead frame 1 on which the semiconductor chip 2 is mounted is set in a feeding mechanism and transported at a predetermined pitch in synchronization with the bonding operation.

An imaging device for recognizing the electrode 2a on the chip surface and a recognition device for calculating the electrode position by processing the captured video signal are provided at a position opposite to the punching position of the set lead frame 1. Based on the output signal generated by the recognition device, the relative position between the lead frame 1 and a capillary for wire supply, which will be described later, is controlled.

That is, the output signal of the recognition device is applied to the lead frame feeder configuration or capillary drive system, and the amount and direction of movement is controlled so that the wire end is at the bonding position.

Further, a capillary 3 for supplying the wire is provided at the punching position 4.

The capillanoy 3 is mounted on an XY table 4 that is movable in the X and Y directions of a plane parallel to the XY plane formed by the semiconductor chip 2.

The displacement amount of the XY table 4 in the X direction and the Y direction is biased by the X direction transmission bar 5 and the Y
It is provided by a direction transmitting bar 6.

The X-direction transmission bar 5 and the Y-direction transmission bar 6 are provided in the same structure, except that their operating directions are different.

Therefore, in order to simplify the explanation, only the movement transmission mechanism in the X direction will be described.

The transmission bar 5 is supported by fitting the bar holder into a groove 8 cut in the base 7.

In this bar holder, the table 7 is attached to the X-direction transmission shaft 9 and converts the rotational movement of the transmission shaft 9 into the X-direction linear movement of the transmission bar 5.3 The bar holder has a limit bar 10 integrated with the table 7. The bar receiver operates a microswitch installed close to the base 7.

The microswitch is a limiter that regulates the movement of the XY table 4 regardless of the timing of punching. When the limits 1 to 10 are in contact with the microswitch, a regulation signal is output, and the XY table 4 and wire bonding are A regulation signal is given to the operation control section to stop the operation.

Therefore, the location where the microswitch is installed determines the movable range of the XY table 4.

The transmission shaft 9 is attached to an X-drive stepping motor 11, and displacement in the X direction is applied via the transmission shaft 9 by rotation of the motor 11.

A driving pulse for rotating the motor 11 is obtained by calculation processing of the electrode position information of the video signal and the capillary origin, and a pulse signal corresponding to the calculation result is applied to the motor 11.

Further attached to the transmission shaft 9 is a disc 12 in which the rings H3a and 13b are bored.

A light emitting element 14 and a light receiving element 15 serving as a position sensor are provided sandwiching the disc 12, and the above-mentioned sulin) 13a, 13b
The movement of the X-direction transmission shaft 9 is detected through.

In other words, the positions of the sulins 13a and 13b formed on the disk 12 are determined to provide a safe operating range for the capillary 3 mounted on the XY table 4, taking into account the area of the top of the lead frame 1, the area of the semiconductor chip, etc. The capillary 3 is set within a range in which it does not come out of the opposing relationship with the lead frame 1 when the capillary 3 moves downward with the capillary 3 and the lead frame 1 facing each other during bonding.

The sensor output formed by the deviation from the set range is provided to the wire punching operation control to stop the wire bonding operation from proceeding to the next step.

The command to stop the punching operation based on the above sensor output is input to the bar receiver with priority over the micro switch operation etc. by the limit par 10 attached to the stand 7, and when the sensor output is given, it is incorporated into the operation control section. The operation is stopped regardless of the program.

In the wire bonding apparatus described above, when a start signal is applied to the wire bonding operation, the lead frame 1 is fed by the feed mechanism until the frame 1 is detected at the bonding position.

The lead carrying the semiconductor chip 2 is sent to the bonding position and remains stationary, and then chip information is taken in by an imaging device and the center position of the chip electrode is determined.

X of the XY table 4 where the amount of movement of the capillary 3 from the origin position is calculated based on the tip electrode center position information.

Provided to Y drive stepping motor.

The XY table 4 is displaced in the X direction and the Y direction by a given amount of movement, but at this time the X direction transmission shaft 9 and the Y direction
If a sensor output is generated during the rotational movement of the direction transmission shaft 9', the sensor output is immediately determined to be abnormal and is transferred to the operation control unit, wire bonding is stopped, and the image pickup device starts capturing chip images for the same lead pair again. repeated.

If the sensor output is given to the operation control unit, it is likely that there is an abnormality in the relead tip shape due to an inappropriate semiconductor chip mounting condition, so the lead pair where the sensor output is formed should be wire bonded. It is also possible to control the frame feeding mechanism so that a new lead pair is brought to the punching position without having to do so.

If no abnormality is detected, the capillary 3 is sent to the electrode center position, and after the capillary 3 faces the electrode 2a, the XY table 4 moves in the Z direction to press the wire at the tip of the capillary to the electrode 2a, and the lead A first punching of the wire is performed on the semiconductor chip 2 of the frame.

It is preferable to restrict the operation of the capillary 3 by the sensor during the first punching, in which the proper punching area is limited to a narrow range, that is, when wire bonding to the semiconductor chip electrode. During the second punching for bonding the other end, the sensor is operated in the same way to set the safe operating range of the capillary, regardless of the moving distance and moving direction of the capillary instructed by calculation processing etc. in the operation control section. The capillary can be controlled to ensure safer operation of the device.

As described above, according to the present invention, since the movement of the XY table is regulated by two types of switches, it is possible to reliably prevent the first punching failure due to malfunction of the It is possible to improve bonding reliability and prevent damage to device parts such as capillaries.

Further, each switch can be connected according to the characteristics of the electric circuit, and the burden on circuit design can be reduced.

It is possible to improve the reliability of wire bonding and prevent damage to device parts such as capillaries.

[Brief explanation of drawings]

The figure is a perspective view of essential parts showing an embodiment according to the present invention. 1: Lead frame, 2: Semiconductor chip, 3: Capillary, 4: XY table, 5: X direction transmission bar, 7: Bar holder is stand, 8: Groove, 9: Transmission shaft, 10: X direction limit bar, 11 Nistipping motor, 12: disc, 13a,
13b Nislit, 14: light emitting element, 15: light receiving element.

Claims (1)

[Scope of utility model registration request] In an automatic wire bonding machine that electrically connects a semiconductor chip mounted on one lead end of a node frame to the other lead end using a wire supplied from a capillary, the lead frame and capillary are placed relative to each other. an XY table for changing the position of the XY table; a limiter provided in the drive system of the XY table for regulating the first movement range of the XY table; and a limiter for regulating the movable range of the capillary during wire bonding between the lead ends; a position sensor that regulates the XY table in a second movement range smaller than the first movement range; a means for inputting a chip image on the lead frame to recognize the bonding position; and position information of the recognition means and the position. 1. An automatic wire bonding apparatus comprising: an XY table driving device to which a sensor output is given, and controlling XY table movement by giving priority to the position sensor output over a limiter.