Browse Prior Art Database

Soldermask Undercut Monitor

IP.com Disclosure Number: IPCOM000116293D
Original Publication Date: 1995-Aug-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Carey, CF: AUTHOR [+4]

Abstract

Soldermask undercut measurement is currently performed by cross section analysis.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Soldermask Undercut Monitor

      Soldermask undercut measurement is currently performed by cross
section analysis.

      This is a time consuming task, and limits the amount of data
which can be collected, especially in a hi-volume manufacturing
environment.  Measurement of this parameter is critical to the
reliability of Flip Chip Modules.

      The solution to this problem is to add this design to the
product artwork, as a manufacturing enhancement or fiducial.  The
solder mask spacing is varied, by design, over the range monitored.
A dye is applied to one side of the pattern.  The dye will flow, by
capillary action, where complete breakthrough has occurred between
adjacent soldermask openings.  Dye will then be visible in the
opposite solder mask opening.

      Knowing the design spacings of the soldermask openings allows
an estimate of the actual undercut present on the part.