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Method of forming patterned polyimide films

  • US 5,470,693 A
  • Filed: 02/18/1992
  • Issued: 11/28/1995
  • Est. Priority Date: 02/18/1992
  • Status: Expired due to Fees
First Claim
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1. A method of producing patterned low thermal coefficient of expansion polyimide films, comprising the steps of:

  • applying a polyamic acid precursor layer onto a substrate wherein said polyamic acid precursor in said layer is capable of imidizing to form a polyimide which has a thermal coefficient of expansion approximately equal to said substrate and is selected from the group consisting of 3,3'"'"',4,4'"'"'-biphenyltetracarboxylic dianhydride-p-phenylenediamine, 3,3,4,4'"'"'-biphenyltetracarboxylic dianhydride-benzidine, pyromellitic dianhydride-p-phenylenediamine, pyromellitic dianhydride-benzidine, and 3,3'"'"'4,4'"'"'-benzophenone tetracarboxylic acid dianhydride-p-phenylenediamine;

    partially baking said polyamic acid precursor layer to a point where a significant amount of casting solvent in said polyamic acid precursor layer has been removed but wherein said polyamic acid precursor layer is still subject to development;

    applying a positive photoresist on said polyamic acid precursor layer;

    imagewise exposing said positive photoresist to radiation through a mask;

    developing said positive photoresist with a first developer which is more active for said positive photoresist than for said polyamic acid precursor layer to yield a structure comprised of a patterned photoresist, a polyamic acid precursor layer and a substrate, said step of developing is performed under conditions where said polyamic acid precursor layer is not etched with said first developer, said first developer being an aqueous developer;

    immersing said substrate in a second developer which is more active for said polyamic acid precursor layer than for said positive photoresist, said second developer being an aqueous developer;

    removing polyamic acid precursor material exposed to said second developer to produce a patterned polyamic acid precursor layer; and

    curing said patterned polyamic acid precursor layer to yield a patterned polyimide which has a low thermal coefficient of expansion.

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