Browse Prior Art Database

Automatic Semiconductor Positioning System Using an Image Dissector

IP.com Disclosure Number: IPCOM000076730D
Original Publication Date: 1972-Apr-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 3 page(s) / 52K

Publishing Venue

IBM

Related People

Eisenstadt, BM: AUTHOR

Abstract

This system features the use of an image-dissector camera to scan over a fixed semiconductor chip and to align a stud mounted on a positioning table with the chip.

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Automatic Semiconductor Positioning System Using an Image Dissector

This system features the use of an image-dissector camera to scan over a fixed semiconductor chip and to align a stud mounted on a positioning table with the chip.

An image-dissector camera 2 is fixedly mounted via a stand 8 to an X-Y-theta positioning table 6. Illumination means 7, which provides illumination to the camera and to the semiconductor chip 3, is also attached to stand 8. A heating column 5 holds chip stud 4. Displacement transducers, not shown, are connected to 4-point locator slides at the heating column, to give the position data of the stud relative to the positioning table.

Image dissector 2 provides a display to a closed-circuit television (CCTV) monitor 12. A sync generator 10 provides timing signals for a CCTV sweep generator 11, which in turn feeds its outputs to the CCTV monitor 12 and to X-Y deflection amplifiers 13 via a deflection control switch 14. The deflection amplifiers cause the image dissector 2 to scan in a normal TV mode. The video output of the camera 2 is fed through amplifier 16, which has a 2-3 MHz bandwidth, to monitor 12. In a typical case, if the image dissector photocathode current density is 2 uA/cm/2/, the aperture diameter is 0.0015''; and if an element dwell time is 2 x 10-7 seconds, then the S/N ratio (peak-to-peak video signal-to- RMS noise) will be about 10 db, thereby giving a usable but relatively low- contrast, low-resolution TV image of the chip.

The image dissector operates in conjunction with process controller 20 and the positioning table, to provide data to determine the chip's position and orientation relative to the stud. Initially, the table is positioned so that the dissector is aligned to scan over images of selected solder balls attached to the chip. Scanning and gathering of data is done by two distinct operations, both under control of process controller 20. For example, in the X direction, process controller 20 directs positioning table 6 to move in that direction at controlled speeds. When the desired X positions are reached, the output from the positioning table shaft encoder will be observed and fed to the process controller.

At that point, the process controller will initiate scanning by the image dissector in t...