Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1999-07-06
2001-02-13
Young, Lee (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S832000, C029S740000, C029S743000, C257S797000, C382S151000
Reexamination Certificate
active
06185816
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
The present invention relates generally to manufacturing systems that use pick and place equipment to handle small components. More specifically, the invention relates to an apparatus and method for aligning a camera to an imprint in a film layer which represents an attach position on a semiconductor workpiece, where a pick and place device picks up the semiconductor workpiece.
II. Description of the Related Art
In the assembly of semiconductor products, relatively small parts or components are picked up and accurately placed in another location. For example, in the assembly of optoelectronic systems, it may be necessary to accurately orient and align optical components, such as semiconductor lasers. In a known pick and place system, an operator manually aligns a vacuum collet with respect to an optical camera. These two devices working together are used to move a workpiece in the manufacturing process. The workpiece may be a chip, a bar, a wafer, etc.
In the known system, a test piece is located below the downward looking camera. Crosshairs, viewed on a monitor, are used to align the camera with an attach position on the test piece, which will be the actual attach position on a semiconductor workpiece in the manufacturing process. The attach position may be near the center of the test piece, which in turn would represent the center of a workpiece, for example. The vacuum collet is then moved over the test piece and lowered until it is slightly above the test piece, near the attach position. The operator then adjusts the position of the collet using x and y coordinates until it appears that it is aligned to what the camera perceives as the attach position. Lastly, the test piece is replaced with an actual semiconductor workpiece.
This manual alignment is performed at an angle and by human eye, thus making the process cumbersome, potentially inaccurate and unrepeatable. Inaccuracy in the procedure will result in the collet being placed some distance from where it was intended to be placed. The margin of error may be defined as the difference between the actual attach position, where the vacuum collet picks up a workpiece, and where the optical collection device perceives the attach position to be.
There exists a need for a pick and place system that provides precise, repeatable and efficient alignment between the pick and place equipment and the camera, such that what is seen by the camera as the attach position is aligned to the actual attach position, where the vacuum collet picks up the workpiece. Such precision will help ensure that the workpiece is ultimately placed in the correct location.
SUMMARY OF THE INVENTION
The present invention relates to a system for handling a semiconductor workpiece, such as a semiconductor chip, laser bar, wafer and the like. The system includes a pick and place device for accurately moving the semiconductor workpiece. The pick and place device is arranged to form an imprint on a film layer to align an optical device. In addition, the system has a control device for moving the pick and place device to a remote location away from the imprint, and an optical device for viewing the imprint while the pick and place device is at the remote location.
According to one aspect of the invention, a device may be provided for aligning the optical device with respect to the imprint on the film layer while the pick and place device is in the remote location.
According to another aspect of the invention, the movement of the pick and place device is controlled in response to the location of the imprint on the film layer.
In a preferred embodiment of the invention, the optical device may be a vision camera with suitable vision control software. The present invention should not be limited, however, to the preferred embodiments described and shown in detail herein.
If desired, the pick and place device may have a source of vacuum and a vacuum collet. In a preferred embodiment of the invention, the pick and place device has an annular tip for forming the imprint on the film layer.
According to another aspect of the invention, the imprint is formed in a film layer provided on a film support. The film layer may be formed, for example, of adhesive tape.
The present invention also relates to a system for aligning a camera, or other optical collection device, to an imprint of a vacuum pick and place device. Thus, the present invention may be used to align the camera to the actual attach position of the pick and place device in a precise, repeatable and efficient manner.
According to another aspect of the invention, the vacuum pick and place device is moved over the film layer to a first (x,y) position, predetermined to be the attach position's coordinates. Once locked into the first position, the vacuum pick and place device then descends on the attach position and makes an imprint of the head of the vacuum pick and place device on the film layer. The vacuum pick and place device then ascends from the film layer and is released from the first position and moved out of the way to a second position.
Then, the optical collection device is aligned to the imprint of the vacuum pick and place device on the film layer. By doing so the optical collection device becomes aligned to the vacuum pick and place device pick up point. This may be accomplished relatively easily by an operator viewing the imprint on a monitor and accurately aligning the crosshairs to the imprint of the vacuum pick and place device on the film layer. The pick and place device is then brought back in and locked into its first (x,y) position where imprinting occurred. Thus, the optical collection and reproduction device and the vacuum pick and place device pick up point are in alignment using the imprint as a reference point employing devices and a methodology which can be replicated.
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patent: 5443354 (1995-08-01), Stone et al.
patent: 5578156 (1996-11-01), Kamakura et al.
patent: 5612787 (1997-03-01), Harvey et al.
patent: 5680698 (1997-10-01), Armington et al.
patent: 5743731 (1998-04-01), Lares et al.
patent: 5946409 (1999-08-01), Hori
patent: 5998878 (1999-12-01), Johnson
Freund Joseph M.
Przybylek George J.
Romero Dennis M.
Chang Rick Kiltae
Dickstein , Shapiro, Morin & Oshinsky, LLP
Lucent Technologies - Inc.
Young Lee
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