Process for removing plating materials from copper-based substrates

  • US 5,755,950 A
  • Filed: 02/13/1997
  • Issued: 05/26/1998
  • Est. Priority Date: 06/07/1995
  • Status: Expired due to Term
First Claim
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1. A method for removing plating materials from a plated substrate comprising a copper-based alloy with a tin-based or tin/lead-based surface plated layer, said method comprising:

  • (1) treating the plated substrate at a temperature of about 50°

    to 150°

    F. with an aqueous etchant solution consisting essentially of about 1 to 50 weight percent of an etchant acid and about 0.1 to 5 weight percent nitric acid, the surface plated layer metals being removed by, and dissolved or suspended in, the aqueous etchant solution and an intermetallic layer containing tin or tin/lead remaining on the treated surface;

    (2) separating the treated substrate and the aqueous etchant solution;

    (3) rinsing the separated substrate from step (2) with water;

    (4) treating the rinsed substrate of step (3) at a temperature of about 70°

    to 210°

    F. with an aqueous immersion solution consisting essentially of about 1 to 50 weight percent of an immersion acid and about 1 to 150 g/l of copper cation in the form of a copper (II) salt, the tin or tin/lead in the intermetallic layer being removed from the substrate and the substrate being rendered essentially free of tin or tin/lead from the surface plated layer; and

    (5) separating the substrate from step (4) from the aqueous immersion solution, wherein the substrate is essentially free of surface plated tin or tin/lead;

    wherein the etchant acid and the immersion acid are independently selected from the group consisting of sulfuric acid and alkane sulfonic acids.

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