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Browse Prior Art Database

Multi-tolerance Flexible Photo Mask

IP.com Disclosure Number: IPCOM000121444D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 1 page(s) / 39K

Publishing Venue

IBM

Related People

Dang, H: AUTHOR [+3]

Abstract

A process is disclosed for resolving wide distortion problems in a via network on multi-layer ceramic products which occur during an expose operation. An expose is a step in the photo-lithographic procedure to imprint a circuit on a substrate, in this case, a multi-layer ceramic substrate.

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Multi-tolerance Flexible Photo Mask

      A process is disclosed for resolving wide distortion
problems in a via network on multi-layer ceramic products which occur
during an expose operation. An expose is a step in the
photo-lithographic procedure to imprint a circuit on a substrate, in
this case, a multi-layer ceramic substrate.

      The problem is encountered when the calculated mask image of
via locations does not coincide with the actual vias on the top
ceramic layer. Primarily this is caused by different shrinkage in the
many ceramic layers, with a resulting non-uniform distortion in the
vias compared to the calculated vias network.

      This mismatch problem can be solved either by:
      (1)  Building a mask with a large capture pads - this is
feasible until the pads become too large or the space between
electrodes becomes too small;  or
      (2)  Building a mask with nominal size pads but with locations
varying according to the actual distortion level of the substrate to
be exposed.

      The disclosed process, which involves building a mask tailored
to a distortion level based on actual measurements of the via network
prior to expose, includes the following steps:
(1)  Design a nominal mask from engineering documents.
(2)  Measure the distortion level of the substrate to be exposed.
(3)  Build a series of low-cost flexible masks with varying degrees
of distortion.
(4)  Visually locate and match this mask image with the via lo...