JPH05129408A - Wire bonding method and equipment - Google Patents

Abstract

PURPOSE:To inspect at once a true wire loop which is not affected by adverse influence like vibration due to conveyance, by detecting a wire after bonding by using a camera for setting the bonding position coordinates. CONSTITUTION:A picture image wherein a semiconductor chip or leads are sensed is displayed on a monitor surface, and two bonding position coordinates P1, P2 are set. A capillary 4 is moved by controlling an XY driver 22 and a Z driver 24, and a wire 3 is connected between an electrode 1A and a lead 2. After bonding, a control equipment 30 determines the equation y=ax+k of a straight line which passes the two designated coordinate points P1 and P2 by calculation. The amount of curl wherein a wire loop is most bent is obtained by calculation and displayed on the monitor. Since the amount of curl of the wire loop can be inspected by a bonding equipment itself, adverse influence due to vibration during conveyance is eliminated, and true inspection results which are reliable can be obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a wire bonding method and apparatus.

[0002]

2. Description of the Related Art Generally, the wire bonding method is as follows.
This is done as described in (1) to (4). 4 to 6, 1 is a semiconductor chip, 1A is an electrode, 2 is a lead of a lead frame, 3 is a wire, and 4 is a capillary.

(1) When performing wire bonding using a bonding device,
It is necessary to set (remember) the bonding position coordinates. This setting work is called "teaching work" and is performed by the operator.

Here, the bonding position coordinates mean the coordinates of the point where the wire 3 is connected on the electrode 1A of the semiconductor chip 1 and the lead 2 of the lead frame.

(2) When the bonding position coordinates are set, the control unit of the bonding apparatus, based on the bonding position coordinates of the electrode 1A and the lead 2 corresponding thereto, the movement information of the capillary 4 between the respective bonding positions. , For example, the Z stroke (A to D), the reverse level (A to B), the reverse amount (B to C), the descending locus (D to E), etc. are calculated and set by a preset arithmetic expression or the like ( (See FIG. 4).

(3) Next, the capillaries 4 move based on the movement information of the capillaries 4 set as described above and the amount of displacement of the electrodes 1A and the leads 2 detected by a camera (not shown), and the capillaries 4 move. A wire 3 is connected between 1A and the lead 2 (see FIG. 5).

(4) When the capillary 4 is moved under the conditions set as described above and the actual bonding is performed, a desired wire loop is not formed, and a curl phenomenon (the formed wire loop from directly above is formed). When viewed, the wire loop may be horizontally curved).

There are various possible causes for this, part 1
As shown in FIG. 6, for example, when the wire 3 is bonded onto the lead 2, the wire 3 led out from the tip of the capillary 4 is too long (a wire feeding amount is defective) and hangs down. It may come in contact with the rounded part at the tip and be flipped outward (a direction orthogonal to the tangent line of the rounded part) (bonding failure).

Therefore, after wire bonding, the formation state of the wire loop is inspected, and if the loop shape is defective,
The Z stroke, the descending locus, etc. of the capillary 4 are adjusted to eliminate defective bonding.

[0010]

However, in the prior art, in order to inspect the formation state of the wire loops, the lead frame after bonding is conveyed to an inspection device called a "projector", and here, each wire loop is inspected. The curl amount was measured and inspected.

However, the wire loop may be deformed by the vibration during the transportation to the inspection device. Therefore, even though the wire loop was normally formed during bonding, it is determined to be abnormal in the inspection after the transfer to the inspection device, which causes confusion in the adjustment of the bonding information (that is, true determination is made). Not).

The present invention aims at enabling a true inspection of wire loops.

[0013]

According to a first aspect of the present invention, an image of a component to be bonded positioned at a bonding work position is captured by a camera, the bonding position coordinates are obtained from the captured image, and the obtained bonding position is obtained. In the wire bonding method of connecting a wire to coordinates, an image of a bonding target component for which the wire bonding operation has been completed is captured again by the camera, and the loop state of the bonded wire is detected from this image.

According to a second aspect of the present invention, an image of a component to be bonded positioned at a bonding work position is captured by a camera, bonding position coordinates are obtained from the captured image, and a wire is connected to the obtained bonding position coordinate. In the bonding device, the two bonding position coordinates P1 obtained from the imaging result of the camera
, A means for obtaining a formula of a straight line passing through P2, and a perpendicular line drawn from the maximum curl point P3 of the loop of the bonded wire obtained from the imaging result of the camera to the straight line passing through the two points P1 and P2. And a means for calculating the length of the.

[0015]

The bonding apparatus itself can inspect the loop state of the wire. That is, a camera that the bonding apparatus originally has for setting the bonding position coordinates is used, and the loop state of the bonded wire can be immediately captured and detected by the camera. Therefore, it is possible to inspect a true wire loop which is not adversely affected by vibration after transportation after bonding, immediately after the bonding is completed.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an example of an arithmetic circuit used for implementing the present invention, FIG. 2 is a schematic diagram showing a monitor screen of a camera, FIG. 3 is a schematic diagram showing a wire loop, and FIG. FIG. 5 is a schematic diagram showing movement information, and FIG. 5 is a schematic diagram showing a wire bonding state.

First, the general procedure of the wire bonding method for carrying out the present invention will be described.

(1) Teaching of bonding position coordinates (see FIGS. 1 and 2) Teaching is performed by capturing an image of the electrode 1A and the lead 2 by an image recognition means. That is, the image pickup means (camera 10) images the semiconductor chip 1 or the leads 2 and displays the imaged image on the monitor 11. At this time, in the center of the screen of the monitor 11, an instruction mark (referred to as "reticle 12") is displayed which indicates the center position of the camera and serves as an alignment when pointing a point on the monitor screen 11A (FIG. 2). reference). And monitor 11
On the electrode 1A or the lead 2 displayed on the reticle 12
By aligning the two bonding position coordinates P1
, P2 are set.

By the way, the camera 10 provided in the bonding apparatus is mounted on the XY table 20, and the XY table manual moving means (called "chessman 21") provided on the operation panel is operated. Therefore, it can be moved in the XY directions via the XY driver 22.

Then, the operator moves the camera 10 by operating the chessman 21 while looking at the image displayed on the monitor 11 to align the reticle 12 with the ideal bonding position on the electrode 1A or the lead 2.
After this alignment, the point designation button 23 on the operation panel is pressed to store the bonding position coordinates in the memory 31 of the arithmetic and control unit 30.

(2) Setting of Capillary Movement Information (See FIG. 4) When the bonding position coordinates are set, the control device 30 included in the bonding device determines the bonding position coordinates of the electrode 1A and the lead 2 corresponding thereto. , Movement information of the capillary 4 between the respective bonding positions, for example, Z stroke (A to D), reverse level (A to B), reverse amount (B to C), descending trajectory (D to).
E) and the like are calculated and set by a preset arithmetic expression or the like.

(3) Wire Bonding by Moving Capillaries (See FIG. 5) The control device 30 controls the XY driver 22 and Z based on the movement information of the capillaries 4 set as described above.
By controlling the driver 24, the capillary 4 is moved to connect the wire 3 between the electrode 1A and the lead 2.

(4) Inspection of wire loop (see FIG. 3) The control device 30 inspects the formation state of the wire loop after wire bonding, and if the loop shape is defective, Z stroke of the capillary 4, descending locus, etc. Adjustment,
Try to eliminate defective bonding. At this time, the controller 30 controls the two designated coordinate points P1, P2 (1
Means for obtaining an equation of a straight line passing through the bonding position coordinate P1 on one electrode and the bonding position coordinate P2 on the corresponding lead, and the designated third coordinate point P
From 3 (the point where the wire loop is most curved in the horizontal direction, that is, the curl with respect to the straight line passing through the two points P1 and P2),
And a means for calculating a length (curl amount) of a perpendicular line drawn from a straight line passing through the points P1 and P2.

The inspection procedure of the wire loop by the control device 30 will be described in detail below. First, when the wire loop is inspected, the coordinate P1 of the electrode 1A which is the first bonding point of the target wire loop is designated (the coordinate P1 and the coordinate P2 on the lead 2 are
Since it is taught in advance, there is no need to store it again. ).

This command causes the camera 10 to move, and the electrode 1A is projected on the monitor 11. At this time, the wire loop captured by the camera 10 is also displayed on the monitor screen 11A (actually, a part of the wire loop is displayed due to the limitation of the screen area). The reticle 12 is displayed in the center of the screen. Therefore, the operator operates the chessman 21 while looking at the monitor 11 and gradually moves the camera 10 to follow the wire loop, and the most curved portion (in the horizontal direction), that is, the maximum curl amount. Find the part. Then, the center of the camera, that is, the reticle 1 is located in the maximum curl amount that is found.
In accordance with 2, press the point designation button 23. As a result, the coordinate point (P3) is stored in the bonding apparatus.

After this, the operator presses a calculation command button on the operation panel (not shown), and the calculation control device 30 starts calculation of the curl amount. The calculation is performed according to a calculation formula described later. Then, the calculated curl amount is displayed on the monitor 11
Is displayed in a predetermined area.

The operator adjusts the bonding information based on the curl amount displayed. Here, the above-mentioned curl amount is calculated from the coordinate point P3 to the bonding position coordinates P1 and P2.
It is the length L of the perpendicular drawn from the straight line passing through
It is calculated by equations (1) to (6).

Two coordinate points P1 (a, b), P2 (c,
Formula of straight line H passing through d)

[0029]

[Equation 1] And At this time, the inclination α is calculated from the coordinates of P1 and P2.

[0030]

[Equation 2] Can be expressed as Also, when x = a, since y = b,

[0031]

[Equation 3] Therefore, substituting equations (2) and (3) into equation (1),

[0032]

[Equation 4] And this is

[0033]

[Equation 5] Can be transformed. Then, from the coordinate point P3 (e, f) to the straight line H
The length L of the perpendicular drawn down is as follows.

[0034]

[Equation 6]

However, according to this embodiment, the following effects (1) to (4) are obtained. Since the curling amount of the wire loop can be inspected by the bonding device itself, the vibration during transportation does not adversely affect the formed wire loop as in the past, and a reliable true wire loop inspection result can be obtained. Obtainable.

Further, since it is not necessary to carry the lead frame, it is possible to eliminate the carrying time which has been conventionally required for carrying out the inspection, and as a result it is possible to shorten the testing time.

Further, since the inspection can be carried out immediately after the bonding is completed, the production of defective semiconductor devices can be minimized (in general, a plurality of semiconductor chips are mounted on one lead frame. Therefore, in wire bonding, one lead frame or one magazine is used as one unit for bonding.
After the bonding for one lead frame or one magazine was completed, the units were transported to the projector one by one. Therefore, many defective semiconductor devices have already been detected by the inspection device until a defective bonding state is found. It had the drawback of being manufactured).

In the above embodiment, the third coordinate point P3 is designated by the operator's manual operation, but it may be automatically detected by using the image recognition means. In this case, the camera follows the coordinate point P3 on the wire loop in order, and at the same time, the length of the perpendicular line drawn from the coordinate point P3 to the straight line passing through P1 and P2 is calculated, and the maximum value of this length is curled. It can also be displayed on the monitor as a quantity.

Further, in the above embodiment, the reference pattern is set together with the bonding position coordinates P1 and P2 during the teaching operation, the image of the bonding target component is captured by the camera at the time of bonding, and the captured image is compared with the reference pattern. Correct the position coordinates, and set the corrected bonding position coordinates to P1,
It may be replaced with P2.

[0040]

As described above, according to the present invention, the true inspection of the wire loop can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of an arithmetic circuit used for implementing the present invention.

FIG. 2 is a schematic diagram showing a monitor screen of a camera.

FIG. 3 is a schematic diagram showing a wire loop.

FIG. 4 is a schematic diagram showing capillary movement information.

FIG. 5 is a schematic diagram showing a wire bonding state.

FIG. 6 is a schematic diagram showing an example of a cause of curl.

[Explanation of symbols]

 1A electrode (bonding target component) 2 lead (bonding target component) 3 wire 10 camera 30 arithmetic and control unit

Claims (2)

[Claims] 1. A wire bonding method in which an image of a bonding target component positioned at a bonding work position is captured by a camera, bonding position coordinates are obtained from the captured image, and a wire is connected to the obtained bonding position coordinates. A wire bonding method, wherein an image of a bonding target component whose operation has been completed is captured again by the camera, and the loop state of the bonded wire is detected from this image. 2. A wire bonding apparatus for capturing an image of a part to be bonded positioned at a bonding work position with a camera, obtaining bonding position coordinates from the captured image, and connecting a wire to the obtained bonding position coordinates, wherein Obtained from imaging results, 2
A means for calculating a formula of a straight line passing through one bonding position coordinate P1 and P2, and a straight line passing through the above two points P1 and P2 from the maximum curl point P3 of the loop of the bonded wire obtained from the imaging result of the camera. A wire bonding apparatus comprising: a means for calculating the length of a perpendicular line that is lowered by calculation.