Browse Prior Art Database

Selective Gold Plating Process

IP.com Disclosure Number: IPCOM000102887D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 47K

Publishing Venue

IBM

Related People

Appelt, BK: AUTHOR [+3]

Abstract

Disclosed is a process for selective nickel/gold electrolytic plating of internal printed circuit board tabs. This process provides for efficient use of precious metal plating solutions, while eliminating the need of the conventional commoning bar plating approach, thus simplifying process operations and circuit line routing traces.

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Selective Gold Plating Process

      Disclosed is a process for selective nickel/gold electrolytic
plating of internal printed circuit board tabs. This process provides
for efficient use of precious metal plating solutions, while
eliminating the need of the conventional commoning bar plating
approach, thus simplifying process operations and circuit line
routing traces.

      The printed circuit board composite laminate is processed
through drilling and electrolytic copper plating in the conventional
manner.  Following copper plating, a dry film photoresist is applied
to both surfaces, and exposed with a mask to define photoresist
openings in areas where gold plating is required.  The gold tab size
is limited only by the resolution capabilities of the lithography
system. The board is then processed through photoresist development
and is ready for deep tank electrolytic nickel/gold plating. In this
embodiment, the copper foil/plating provides electrical commoning to
the areas where gold plating is desired, while the photoresist
coating prevents plating in all other areas of the board.  After
plating of the gold tabs, the photoresist is stripped, and a second
photoresist is applied to the board for subtractive etching of the
circuit lines.  Registration of the circuit pattern resist to the
previously defined gold plated tabs is critical to prevent
undercutting of the gold tabs during circuit line etching.  A relaxed
registration tolerance may be achieved if the g...