Browse Prior Art Database

Algorithm to Detect Bent Lead Defects of Tab Package Outer Leads

IP.com Disclosure Number: IPCOM000121532D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Nakano, H: AUTHOR

Abstract

This article describes an apparatus and an algorithm to detect bent lead defects of TAB package outer leads. The apparatus uses a camera disposed above the package and a lighting device arranged below the camera. An area of interest is set in the image to cover the knee position of leads, and projection along Y-axis and averaging along X-axis are performed with respect to the area of interest.

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Algorithm to Detect Bent Lead Defects of Tab Package Outer Leads

      This article describes an apparatus and an algorithm to
detect bent lead defects of TAB package outer leads.  The apparatus
uses a camera disposed above the package and a lighting device
arranged below the camera.  An area of interest is set in the image
to cover the knee position of leads, and projection along Y-axis and
averaging along X-axis are performed with respect to the area of
interest.

      An image of leads of TAB package solder-bonded to substrate is
captured by a camera (Fig. 1).  The following operations are
performed on the image (Fig. 2):
 1. Set an area of interest to cover the knee position of leads. Bend
of lead appears around the knee position.
 2. Perform projection (summing of gray level of each pixel) along
y-axis (Fig. 2B).  Bent lead usually provides less bright portions in
the image.
 3. Perform averaging by lead width with respect to the result of
projection in step 2 (Fig. 2C).

      The peak of the waveform in Fig. 2C will appear at the center
of each of the leads.  Suppose there is a bent lead defect in the
window, the height of the peak for the lead will be lower than those
for other acceptable leads.  To properly set a threshold for peak
detection, bent lead defects can be determined.