Patent Number: 6,168,725

Title: Etching of Al-Cu layers to form electronic circuits using base solutions including nitrites, borates or bromates

Abstract: The invention is an aluminum etchant and method for chemically milling aluminum from, according to a preferred embodiment, a copper-aluminum-copper tri-metal layer to form three-dimensional circuits. The tri-metal comprises copper circuit patterns present on opposing surfaces of an aluminum foil, one of the copper patterns being laminated on a substrate. The etchant comprises an aqueous solution of 60 to 500 g/l base selected from (a) sodium hydroxide, (b) potassium hydroxide, and (c) their mixture; and 30 to 500 g/l of an additive selected from nitrite salt, a borate salt, a bromate salt, or mixture of any of them. The method comprises contacting the tri-metal with the etchant at a temperature between 25 and C. for a time sufficient to remove a desired amount of the aluminum layer and provide (rigid, flexible, or 3-dimensional) electronic circuitry which may contain multiple conductive circuit layers.

Inventors: Achari; Achyuta (Canton, MI), Paruchuri; Mohan R. (Canton, MI)

Assignee: Visteon Global Technologies, Inc.

International Classification: C23F 1/36 (20060101); C23F 1/10 (20060101); H05K 3/06 (20060101); H05K 3/20 (20060101); H05K 3/38 (20060101); H05K 3/46 (20060101); C23F 001/02 (); H05K 003/06 ()

Expiration Date: 01/02/2018