Patents by Inventor Akira Tokoh

Akira Tokoh has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5449584
    Abstract: The present invention provides a positive photo-sensitive resin composition comprising a polybenzoxazole precursor as a base resin, an organic solvent-soluble polymer or its precursor (e.g., a polyamic acid) as a component for imparting improved adhesion, flexibility or heat resistance, and a diazoquinone compound and/or a dihydropyridine compound as a photosensitive agent. This photo-sensitive resin composition can form a pattern of high resolution and further has excellent adhesion and mechanical properties. The present invention further provides three novel diazoquinone compounds as a photo-sensitive agent, which compounds give high resolution, high contrast and thick-film formability when compounded in a positive photo-sensitive resin composition. The present invention furthermore provides a new type positive photo-sensitive resin composition obtained by reacting a polybenzoxazole precursor with a diazoquinone compound as a photo-sensitive agent.
    Type: Grant
    Filed: March 18, 1994
    Date of Patent: September 12, 1995
    Assignee: Sumitomo Bakelite Company, Ltd.
    Inventors: Toshio Banba, Etsu Takeuchi, Toshiro Takeda, Naoshige Takeda, Akira Tokoh
  • Patent number: 5385808
    Abstract: The present invention provides a photosensitive resin composition which comprises as essential components:(A) a polyamic acid having a recurring unit represented by the following formula [I]: ##STR1## wherein 0.5-50 mol % of R.sub.1 consists of a silicone diamine residue represented by the following formula [II]: ##STR2## wherein n represents an integer of 1-50, and the remainder of 50-99.5 mol % of R.sub.1 consists of an organic group selected from the group consisting of an aromatic group, an aliphatic group, an alicyclic group, and a heterocyclic group, and R.sub.2 consists of an organic group selected from the group consisting of an aromatic group, an aliphatic group, an alicyclic group, a heterocyclic group, and a silicone group, and m represents 1 or 2,(B) an amide compound having carbon-carbon double bond, and(C) a photosensitizer.The present invention further provides a semiconductor apparatus in which the above composition is used.
    Type: Grant
    Filed: October 25, 1993
    Date of Patent: January 31, 1995
    Assignee: Sumitomo Bakelite Company Limited
    Inventors: Akira Tokoh, Nobuyuki Sashida, Etsu Takeuchi, Takashi Hirano
  • Patent number: 5238784
    Abstract: The present invention provides a photosensitive resin composition which comprises, as essential components:(A) a polyamic acid having a recurring unit represented by the following formula [I]: ##STR1## wherein R.sub.1 and R.sub.2 each represents an organic group selected from the group consisting of an aromatic group, an alicyclic group, an aliphatic group, and a heterocyclic group and m is 1 or 2,(B) an amide compound having carbon-carbon double bond, and(C) a photosensitizer.
    Type: Grant
    Filed: November 28, 1990
    Date of Patent: August 24, 1993
    Assignee: Sumitomo Bakelite Company Limited
    Inventors: Akira Tokoh, Nobuyuki Sashida, Etsu Takeuchi, Takashi Hirano
  • Patent number: 5206337
    Abstract: The present invention provides an oligomer having an inherent viscosity .eta. of 0.001-0.5 dl/g as measured at a concentration of 0.5 g/dl in N-methyl-2-pyrrolidone at 30.degree. C., which has been obtained by subjecting to polymerization and imidization (a) an acid component consisting of an aromatic tetracarboxylic acid dianhydride and/or a derivative thereof and (b) a diamine component consisting of 5-100 mole % of a diaminosiloxane represented by the undermentioned formula (I) and 95-0 mole % of an organic diamine other than the formula (I): ##STR1## wherein R.sub.1 is a divalent aliphatic group of 1-5 carbon atoms or a divalent aromatic group of 6 or more carbon atoms; R.sub.2 and R.sub.3 are each a monovalent aliphatic or aromatic group and may be the same or different; and m is an integer of 1-100, as well as an oligomer solution obtained by dissolving the above oligomer in an organic solvent.
    Type: Grant
    Filed: May 7, 1991
    Date of Patent: April 27, 1993
    Assignee: Sumitomo Bakelite Company Limited
    Inventors: Toshiro Takeda, Naoshige Takeda, Akira Tokoh