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High-Speed, Improved Quality Hybrid Process for Producing Small Holes in Printed Wiring Board Laminate

IP.com Disclosure Number: IPCOM000116503D
Original Publication Date: 1995-Sep-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Harkins, MG: AUTHOR [+2]

Abstract

Disclosed in this invention is a high-quality hybrid process for producing small holes in the Printed Wiring Board (PWB) laminates. The process consists of laser drilling followed by a reaming operation in order to produce fine smooth holes for subsequent processing.

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High-Speed, Improved Quality Hybrid Process for Producing Small Holes
in Printed Wiring Board Laminate

      Disclosed in this invention is a high-quality hybrid process
for producing small holes in the Printed Wiring Board (PWB)
laminates.  The process consists of laser drilling followed by a
reaming operation in order to produce fine smooth holes for
subsequent processing.

      As the first step of the process, lasers such as C02 or excimer
with controlled pulses of energy are used to produce holes of
requisite diameter.  The process can produce about 80 holes per
second per panel as opposed to four holes per second by mechanical
drilling, a factor of 20 in terms of speed.  The typical holes
produced by lasers are conical in shape, with irregular internal
surface, and also contain some debris due to the burning nature of
the laser processing.  Fig. 1 shows the schematic of a typical
multi-layer PWB holecross-section after laser drilling.

      The second step in the process is the reaming process that is
similar to the mechanical drilling process.  A drill bit of
appropriate final size can be used for this step, but a reaming bit
such as the one with a two-flute commercially developed designs is
more suitable for this purpose.  The reaming bit is such as to remove
several mils of material from the hole walls rather than removing all
of the material as is done in conventional mechanical drilling.
Thus, the bit can be similar to the regular drill bit bu...