Browse Prior Art Database

Visual Check of Drilled Hole Depth

IP.com Disclosure Number: IPCOM000117411D
Original Publication Date: 1996-Feb-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Cortez, JT: AUTHOR [+2]

Abstract

In Printed Wire Board (PWB) manufacturing, drill machines must drill up to one million holes in a twenty-four hour period. Each hole must be drilled to the correct depth to properly manufacture the board while simultaneously preventing excessive drill bit wear. A method is disclosed that increases the effectiveness and reduces the time required for determining drilled hole depth.

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This is the abbreviated version, containing approximately 83% of the total text.

Visual Check of Drilled Hole Depth

      In Printed Wire Board (PWB) manufacturing, drill machines must
drill up to one million holes in a twenty-four hour period.  Each
hole must be drilled to the correct depth to properly manufacture the
board while simultaneously preventing excessive drill bit wear.  A
method is disclosed that increases the effectiveness and reduces the
time required for determining drilled hole depth.

      Current methods require removing a disposable board (backer
board) from underneath the printed circuit board and determining the
drilled hole depth into the backer board.  This determination is done
by taking actual measurements or by judging the depth based on
overall appearance and experience.  Both methods of determining
drilled hole depth are time-consuming and subject to error.

      The method disclosed here requires the backer board to be
produced with an internal plane of a color that is different than the
exterior.  When the drill bit enters the backer board and then
retracts, the different color becomes visible.  The accuracy of the
depth of the colored layer determines the accuracy of measurement for
the drilled hole; i.e., if the colored layer is exactly 0.010 inches
into the board, then drilled holes that expose this layer are at
least 0.010 inches deep.

      The thickness of the colored layer can also be used to
determine drilled hole depth; i.e., a colored layer that is 0.005
inches thick and 0.010 inches into...