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Browse Prior Art Database

Hole Fill Detection Method

IP.com Disclosure Number: IPCOM000103429D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 42K

Publishing Venue

IBM

Related People

Ruane, R: AUTHOR [+2]

Abstract

Disclosed is a method which allows immediate detection of whether or not the clearance holes are completely filled. The over 60,000 holes/panel are typically less than 7 mils in diameter and less than 2 mils in height. It is important to completely fill these etched clearance holes with the designated dielectric material since a laser is used to produce a second hole in the center of the filled clearance hole.

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

Hole Fill Detection Method

      Disclosed is a method which allows immediate detection of
whether or not the clearance holes are completely filled. The over
60,000 holes/panel are typically less than 7 mils in diameter and
less than 2 mils in height.  It is important to completely fill these
etched clearance holes with the designated dielectric material since
a laser is used to produce a second hole in the center of the filled
clearance hole.

      Incomplete filling of the initial clearance holes will cause
subsequent plating problems shorting the laser drilled hole to the
extremities of the clearance hole. Cross-sectioning is still
presently used to detect incomplete hole fill, but it is not feasible
to cross-section all 60,000+ holes.

      This new hole fill detection method works by placing the
dielectric material on one side of the panel to be filled and forcing
the dielectric through the holes until it meets the top copper
release sheet.  Following lamination, the release sheet is removed
and all 60,000 are visible and able to be scanned under a microscope
for complete hole fill.  If the holes are completely filled using
only one sheet of dielectric material filling from one side, when
using two sheets (one/side) the holes must be filled as
experimentation as shown.  See figure at end of article depicting the
one sided fill vehicle.

      Disclosed anonymously.