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Browse Prior Art Database

Plated through Hole with Sloped Edge

IP.com Disclosure Number: IPCOM000106251D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Yamanaka, K: AUTHOR

Abstract

Disclosed is a plated through hole (PTH) with sloped edge which is effective to improve reliability of PTH. The sloped edge can be obtained by using a photosensitive material as an insulating layer of a printed circuit board.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 97% of the total text.

Plated through Hole with Sloped Edge

      Disclosed is a plated through hole (PTH) with sloped edge which
is effective to improve reliability of PTH.  The sloped edge can be
obtained by using a photosensitive material as an insulating layer of
a printed circuit board.

      The figure shows the present process for forming PTHs with
sloped edge.  A photosensitive material is applied, as an insulating
layer, to the surface of a circuit board.  The photosensitive layer
is selectively exposed and developed such that openings are formed at
the positions where through holes are to be made by drilling.  The
sloped edge can be produced in the openings by controlling the
photoprocess parameters for opening formation.  Then, through holes
are formed by drilling.  Copper is deposited by plating on the inner
wall of the through holes and the surface of the sloped openings and
then the surface of the plated copper is buffed to remove nodules
made in the plating process.  Finally, the copper layer is
circuitized by patterning and etching.  Alternatively, it may be
possible to plate the sloped openings with copper prior to the
through hole drilling and thereafter perform the through hole
drilling and through hole plating.

      Without sloped edge, the plated copper will get thinner at the
sharp upper edges and cracks occur in the buffing process, thereby
degrading reliability of PTHs significantly and, in the worst case,
causing an open circuit defect.  The use of...