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Copper Pretreatment Suitable for Electrophoretic Deposition of Polyimide

IP.com Disclosure Number: IPCOM000110630D
Original Publication Date: 1992-Dec-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 1 page(s) / 39K

Publishing Venue

IBM

Related People

Buchwalter, SL: AUTHOR [+3]

Abstract

Disclosed is a process for pretreating copper surfaces in order to prepare them for coating with an organic film, specifically a polyimide film deposited by electrophoretic deposition. Many commercial treatments exist for copper to give a controlled thickness of adherent oxide. None were found which were suitable for subsequent electrocoating with polyimide. What is needed is a partially insulating, uniform film of oxide which is not disrupted by the high pH environment generated during cathodic electrophoretic deposition of polyimide (see US Patent 4,832,808).

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Copper Pretreatment Suitable for Electrophoretic Deposition of Polyimide

       Disclosed is a process for pretreating copper surfaces in
order to prepare them for coating with an organic film, specifically
a polyimide film deposited by electrophoretic deposition.  Many
commercial treatments exist for copper to give a controlled thickness
of adherent oxide.  None were found which were suitable for
subsequent electrocoating with polyimide.  What is needed is a
partially insulating, uniform film of oxide which is not disrupted by
the high pH environment generated during cathodic electrophoretic
deposition of polyimide (see US Patent 4,832,808).

      The process for pretreatment of the copper is as follows.  The
copper surface is cleaned in a basic detergent solution containing 11
g of sodium hydroxide, a spatula of Alconox* detergent at 75oC for 5
minutes, then rinsed with deionized water.  The copper was then
etched for 1 minute at 40oC in acidic ammonium persulfate solution,
i.e., 200 g ammonium peroxydisulfate, 800 mL deionized water and 100
mL concentrated sulfuric acid.  After rinsing with deionized water,
the copper was etched in dilute sulfuric acid (200 mL concentrated
sulfuric acid, 1800 mL deionized water) at room temperature for 2
minutes, then rinsed again with deionized water.  Finally, the copper
was oxidized in an ammonium persulfate solution (0.1 g potassium
hydroxide, 1900 mL deionized water, 19 g ammonium peroxydisulfate) at
room temperatur...