Browse Prior Art Database

Individual Chip Inspection System

IP.com Disclosure Number: IPCOM000113228D
Original Publication Date: 1994-Jul-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 77K

Publishing Venue

IBM

Related People

Edmundson, RJ: AUTHOR [+3]

Abstract

A faster and more reliable means was required for transfer and optical inspection of diced silicon memory and logic chips following burn-in testing. By satisfying this requirement, the Individual Chip Inspection Station (ICIS) disclosed herein permitted a significant increase in efficient and throughput in the manufacture of these chips.

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Individual Chip Inspection System

      A faster and more reliable means was required for transfer and
optical inspection of diced silicon memory and logic chips following
burn-in testing.  By satisfying this requirement, the Individual Chip
Inspection Station (ICIS) disclosed herein permitted a significant
increase in efficient and throughput in the manufacture of these
chips.

      Diced silicon logic and memory chips for certain critical
applications are soldered onto a test substrate for burn-in testing,
then unsoldered afterward.  This process deforms the Controlled
Collapse Chip Contact (C4) solder balls (or pads), which must be
reflowed, then visually inspected to detect pads that are undersized
or damaged.  In prior art, an acceptable level of reliability could
only be achieved by a manual process in which skilled technicians
handled each chip individually, subjecting it to three inspections
under a microscope.

      ICIS (Figure) is a standalone workstation using a Programmable
Chip Handler (PCH) and an Oblique Viewing Microscope (OVM) under the
control of separate microprocessors for the transfer and optical
inspection of C4 solder pads.  Microprocessor PC1 controls the PCH,
which transfers the chips between reflow boats and the tool test
area, and an X-Y stage, which orients them properly for testing.
Light aimed at the chip surface from an angle casts shadows for each
pad.  The resulting image seen by the OVM appears as a top view of
the pads and their shadows.  The image of each pad, captured by a
camera, is evaluated by an algorithm under...