Browse Prior Art Database

Dimensionally Stable Two Metal Layer Flexible Circuit Card

IP.com Disclosure Number: IPCOM000121585D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Coteus, PW: AUTHOR [+3]

Abstract

Disclosed is a method for filling vias without seeding/activation of the dielectric. In this method, copper is electroplated into the vias through the dielectric, in order to electrically short the front and back sides of the circuit card. In order to achieve this, a continuous sheet of copper is left across the back side of the via, and the copperz surface inside the hole is used as an electroplating surface. The hole is filled by masking the back surface of the substrate and effectively plating only into the hole. The figure shows this arrangement.

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Dimensionally Stable Two Metal Layer Flexible Circuit Card

      Disclosed is a method for filling vias without
seeding/activation of the dielectric.  In this method, copper is
electroplated into the vias through the dielectric, in order to
electrically short the front and back sides of the circuit card.  In
order to achieve this, a continuous sheet of copper is left across
the back side of the via, and the copperz surface inside the hole is
used as an electroplating surface.  The hole is filled by masking the
back surface of the substrate and effectively plating only into the
hole.  The figure shows this arrangement.

      A basic process for implementing this invention is as follows:
           Blanket plate one side ("back" side) of seeded dielectric
starting material.
           Form vias through dielectric from front side.
           Blanket mask back side with photoresist.
           Electroplate part with both sides biased.
           (NOTE:  This step blanket plates the front side, and fills
the via.)
           Remove back-side photoresist.
           Subtractively pattern both sides.
      Variations on this process could include:
           pattern-plating the front side simultaneously with
via-plating, and
          biasing the front and back sides differently to fill a 50
mm (2-mil) via in the same amount of time that 25 mm (1 mil) of
front-side metal is...