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Process for etching a semiconductor lead frame

  • US 5,683,943 A
  • Filed: 06/12/1995
  • Issued: 11/04/1997
  • Est. Priority Date: 06/14/1994
  • Status: Expired due to Term
First Claim
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1. A method for producing a lead frame having a plurality of outer leads and a plurality of inner leads respectively having tips, for a resin-sealed semiconductor package, comprising:

  • coating a first and a second major surface of a blank for a lead frame with a first and a second photoresist layer, respectively;

    forming a first resist pattern having a first opening on the first major surface of the blank by exposing the first photoresist layer through a first pattern mask and a second resist pattern having second openings on the second major surface of the blank by exposing the second photoresist layer through a second pattern mask;

    applying a first etchant to at least the first major surface of the blank to form an etched recess;

    cleaning the surface of the etched recess formed in the first major surface of the blank after applying the first etchant;

    pickling the cleaned surface of the etched recess to remove oxides and hydroxides tarnishing the surface of the etched surface;

    forming a protective film over the pickled surface of the etched recess to prevent oxidation and hydraulic;

    forming an etch-resistant layer of an etch-resistant material to fill the etched recess in the first major surface of the blank;

    applying a second etchant to the second major surface of the blank to etch through remaining portions of the blank; and

    removing the etch resistant layer, the first resist pattern and the second resist pattern from the resulting lead frame and cleaning the lead frame.

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