Browse Prior Art Database

Data Reduction Algorithm for Line Scan Profiles

IP.com Disclosure Number: IPCOM000108412D
Original Publication Date: 1992-May-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 52K

Publishing Venue

IBM

Related People

Katyl, RH: AUTHOR

Abstract

Thickness profile instruments presently do not readily automatically measure multiple line profiles such as occur in electronic packaging on circuit lines on printed circuit boards or in the inner lead area of TAB chip carriers. Disclosed is a computer procedure for producing line thickness readings from scan data.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 82% of the total text.

Data Reduction Algorithm for Line Scan Profiles

      Thickness profile instruments presently do not readily
automatically measure multiple line profiles such as occur in
electronic packaging on circuit lines on printed circuit boards or in
the inner lead area of TAB chip carriers. Disclosed is a computer
procedure for producing line thickness readings from scan data.

      There are four steps to the procedure:
1.   DATA PRE-PROCESSING - Scan data usually has a wavy baseline due
to non-flatness of the substrate.  In this step the baseline is
extracted, smoothed, extraneous data removed, and subtracted from the
incoming scan data.
2.   BASELINE FINDER - To determine thickness, a starting reference
height must be determined.  The mode of a clipped section of data is
found.  Data is clipped so that the sample for the mode calculation
is preferentially baseline data.  To check on baseline quality, the
value of the distribution is checked at its mode and median point.
For a good baseline, the peak distribution value should exceed its
50% point by a tolerance if the baseline quality is good, i.e., it is
confined over a small range of values.
3.   CORNER FINDER - Scan data is smoothed, extraneous data clipped,
and corners of circuit lines found by taking successive differences.
Position of corners found by testing algebraic sign.  Distance
between corners screened for reasonableness, and extraneous data
removed.
4.   THICKNESS CALCULATOR - To check for extra...