Methods of strengthening bonds
AssigneeWestern Electric Company, Inc.
InventorWilliam F. Glick
Life of this patent
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Abstract
The adherence of thin-film conductors to supporting substrates, and therefore the strength of external lead bonds made to the conductors, is increased by forming the conductors first and then heat treating them in air. The conductors may be formed from layers of titanium, palladium and gold sequentially deposited on the substrate or, in order to reduce the amount of gold, a portion of it may be replaced by copper and nickel.
Claims8
A method of strengthening the bond between a thin-film conductor and an alumina substrate on which the conductor is formed, which comprises the sequential steps of:
- depositing at least two metal layers, the first of which is titanium and the second is palladium, on said substrate to form a thin film of conductive material thereon;
- removing a portion of the conductive material to form at least one thin-film conductor from said material, said conductor having exposed edges;
- and
- heating the substrate and conductor for a predetermined period in an oxidizing atmosphere to improve the strength of the bond between the conductor and the substrate.
A method of improving bond strength between a thin film conductor and an alumina substrate on which the conductor is formed, comprising the sequential steps of:
- a. depositing successive layers of an adhesive metal of titanium and a conductive metal of palladium starting with the adhesive metal against the substrate;
- b. removing those portions of the adhesive and conductive metal layer not needed for the conductor to form and expose the edges of said conductor;
- and
- c. heating the substrate, and conductor so formed, in air for a predetermined length of time to improve the strength of the bond between the conductor and the substrate.
A method of strengthening the bond between a thin film conductor and an alumina substrate on which the conductor is formed comprising the sequential steps of:
- evaporating a layer of titanium on the alumina substrate;
- evaporating a layer of palladium on the titanium;
- plating a layer of copper on the palladium;
- plating a layer of nickel on the copper;
- plating a layer of gold on the nickel, the combined evaporated and plated layers forming a single thin-film coating of conductive material on the substrate;
- removing at least a portion of the material to form a thin-film conductor;
- and
- heating substrate and the conductor for a predetermined period of time in air to improve the strength of the bond between the conductor and the substrate.
Dependencies are inferred from the claim text.