JPH0133940B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recognizing the position of an object to be recognized, such as a pellet, suitable for wire bonding of semiconductor devices, and particularly to an automatic position recognition method thereof.

Wire bonding, which is performed as one of the manufacturing processes of semiconductor devices, currently employs a method using an automatic position recognition wire bonder. That is,
This method uses an ITV camera to photograph the surface of a pellet or a lead such as a lead frame lead for wire bonding, and electrically and optically detects the image of the pellet or lead surface projected on a viewing screen. In this method, the position of the pellet or lead is calculated and recognized, and the wire bonding position is controlled by an automatic wire bonder based on the recognition result to perform appropriate wire bonding. In this case, to recognize the position of the pellet, etc., a reference measurement point is determined in advance on the pellet, etc., and when the pellet, etc. is projected, the position of this measurement point on the screen is detected.

For example, FIG. 1 shows an example of this. Among the plural pads provided on the pellet 1, diagonally located pads 2 and 3 are set as measurement points, respectively, and each pad 2, 3 (more precisely, The pellet parts including the corners of pads 2 and 3 are shown on the ITV viewing screens 4 and 5, respectively.
image and perform position recognition. Then, as a check for misrecognition, the distance l between both pads 2 and 3 is calculated, and when one pad 3 is used as a reference, the other pad 2 is located on the circumference with the distance l as the radius. This is to check whether there is any misrecognition.

However, in this method, rotational movement occurs in the pellet 1 for some reason, and the pellet 1
Even when the value fluctuates as shown by the imaginary line in the same figure,
Since the distance between the pads 2 and 3 is constant, this may be recognized as a good pellet (placed within the required range). If such erroneous recognition occurs, the wire bonder in the subsequent process will also be defective, resulting in a problem of poor product yield.

Therefore, an object of the present invention is to use one of the measurement points as a reference and determine whether or not the other measurement point exists within the tolerance range of the one measurement point in the X direction and the Y direction. It is an object of the present invention to provide a position recognition method that can reliably recognize the position of a body to be recognized such as the above, prevent erroneous recognition, and perform wire bonding with a high yield.

Hereinafter, the present invention will be explained based on the drawings.

FIG. 2 is a block diagram of an apparatus for carrying out the method of the present invention, in which a package 6 to which pellets 1 are bonded is set on a base 7, and its diagonal parts are photographed by an ITV camera 8. The pellet 1 was measured at the corners of pads 2 and 3 placed at diagonal positions among a plurality of pads, as shown in FIG. 3, and each pad 2 and 3 was photographed with an ITV camera 8. are displayed on the ITV monitor screen 4, and each position is recognized by an optical method and calculation by the calculation unit 10. The calculation unit 10 is the control unit 1
The control unit 11 outputs the position signal of the measurement point to the control unit 11.
The X and Y tables 13 of the wire bonder 12 are operated to determine the sealing position of the wire bonder.

An erroneous recognition check section 14 is provided between the arithmetic section 10 and the control section 11, and uses the output of the arithmetic section 10 to recognize the relative positions of the measurement points 2a and 3a. That is, using the position of one measurement point 3a as a reference,
Tolerance ranges Xa and Ya are set apart by a predetermined distance in the direction, and the other measurement point 2a is set within these tolerance ranges Xa and Ya.
The comparison is made to see if it exists in any of the ranges.

Therefore, the method for recognizing the position of objects to be recognized, such as pellets, of the present invention using the above-mentioned device first includes the following steps.
The ITV camera 4 photographs the pellet site including the measurement points 2a and 3a, the measurement points 2a and 3a (pads 2 and 3) are detected by an optical method on the ITV monitor screen 4, and the calculation unit 10 detects each measurement point. Recognize 2a and 3a. At approximately the same time, the misrecognition check section 14 checks whether or not the other measurement point 2a exists within the required range in the X direction and the Y direction (the above-mentioned tolerance ranges Xa, Ya) using one measurement point 3a as a reference. judge. When the other measurement point 3a is within the allowable range, a confirmation signal is output to the control section 11 to determine whether the package to which the pellets have been bonded is acceptable. In this case, the wire bonder 12 can be activated immediately to perform wire bonding, or the good judgment can be memorized and used for later wire bonding. On the other hand, if the other measurement point 2a is not within the allowable range, it means that the pellet position was incorrectly recognized, and this pellet is excluded from the subsequent process and excluded from the wire bonding target. In some cases, the pellet position must be re-recognized and the erroneous recognition check must be performed again.

Measurement point 2 provided on pellet 1 in this way
By checking the position of the pellet by checking whether the other one of a and 3a exists within the tolerance range in the X direction and Y direction with one as a reference, there will be no misrecognition and reliable position recognition can be achieved. It can be done.

The objects to be recognized are pellets, packages,
There are various types of leads, such as a lead built into a package.

As described above, according to the method for recognizing the position of pellets, etc. of the present invention, one of at least two measurement points provided on the pellet, etc. is used as a reference, and a predetermined tolerance range in the X direction and Y direction with respect to this one measurement point is determined. Since pellet position recognition is confirmed by determining whether or not the other measurement point exists within the area, there is no possibility of misrecognition compared to the conventional method that uses the distance between two points. This has the effect that position recognition can be performed reliably.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the conventional method, FIG. 2 is a configuration diagram of an apparatus for implementing the method of the present invention, and FIG. 3 is an explanatory diagram of the method of the present invention. 1...Pellet, 2,3...Pad, 2a,3
a...Measurement point, 4...ITV visual field screen, 8...
ITV camera, 10... calculation section, 11... control section,
14...Misrecognition check section.

Claims (1)

[Claims] 1. At least two or more measurement points are provided on an object whose position is to be recognized such as a pellet, the position of one measurement point is recognized and used as a reference, and the other measurement point is set in the X direction and Y direction with respect to the one measurement point. A position recognition method characterized by determining whether or not the position exists within each allowable range.