Gold-Silver Wire Bonding via Intermediary Copper Layer

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Solution Overview

Problem

Existing methods for manufacturing two-layer metal wires made of gold-based alloys and silver result in significant machining waste and are prone to surface flaws, oxidation, and separation of the gold-silver interface, making them costly and inefficient.

Innovation Solution

A method involving a copper thickness interposed between the gold-based alloy outer tube and silver alloy inner tube, welded in a furnace with belt conveyors at different temperatures, facilitating particle migration and interpenetration, and subsequent removal of the low-melting copper layer to form a stable two-layer wire, allowing for machining without surface flaws and oxidation resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If direct welding of gold-based alloy outer tube and silver inner tube is performed, then manufacturing process is simple, but machining waste is significant and surface flaws occur

Engineering Contradiction:
Improvemanufacturing process simplicityVSAvoidmachining waste
Core Design Contradiction:
Ease of manufactureVSLoss of substance

Solution Approach 1:

A copper layer is introduced as an intermediary between the gold-based alloy outer tube and silver inner tube. This copper layer acts as a mediator that facilitates welding and bonding while reducing machining waste. The copper layer is subsequently removed after serving its purpose, leaving a clean interface between the gold and silver layers without the need for excessive machining.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The copper layer is placed in advance between the gold and silver tubes before welding. This preliminary action prepares the interface for optimal bonding by providing a material that is compatible with both gold and silver, enabling better adhesion and reducing the need for post-welding machining to remove defects or excess material.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If gold-based alloy coating is applied on silver matrix, then oxidation resistance is improved, but interface separation and surface flaws occur

Engineering Contradiction:
Improveoxidation resistanceVSAvoidinterface stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The copper layer serves as a mediator that improves the bonding between gold-based alloy and silver. Copper has good compatibility with both gold and silver, creating a stable gradient interface that prevents separation. This intermediary layer ensures the structural stability of the composite wire while maintaining the oxidation resistance provided by the gold coating.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Strength

If conventional brazing operation is used between gold tube and silver tube, then joining is achieved, but machining waste and surface imperfections increase

Engineering Contradiction:
Improvejoining strengthVSAvoidsurface quality
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The copper layer acts as a brazing intermediary that facilitates strong joining between gold and silver tubes. During the brazing process, the copper layer promotes wetting and bonding, achieving strong joint strength. After brazing, the copper layer is removed, leaving a clean interface without surface imperfections that would otherwise require extensive machining to correct.

Inventive Principle:
Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method reduces machining waste, ensures oxidation resistance, and allows for versatile machining of the two-layer wire, maintaining economic competitiveness by using readily available materials and common machinery, while avoiding surface imperfections and separation issues.

Implementation Method 1

welded in a furnace with belt conveyors at different temperatures, facilitating particle migration and interpenetration

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 2

welded in a furnace with belt conveyors at different temperatures

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

removing the low-melting metal material from said compound metal wire

Methodology Applied
Scientific EffectMelting: Melting

Data Source

PatentEP3787812B1Method for the realization of a two layer metal wire made of gold-based alloy and of silver
Publication Date: 2024.07.10 DEL PIA
  • EP3787812B1 patent drawingFigure 1
  • EP3787812B1 patent drawingFigure 2
  • EP3787812B1 patent drawingFigure 3

AI summary

A method of manufacturing a two-layer metal wire, in particular in a gold- based alloy and of silver, which comprises a succession of steps which consist in coupling an outer metal tube (2) to an inner metal tube (4) interposing a first binding thickness (3) in low-melting metal material, welding the inner surface (12) of the outer metal tube (2) to the outer surface (13') of the first binding thickness (3) and the inner surface (13") of the same first binding thickness (3) to the outer surface (141) of the inner metal tube (4), to firmly associate the outer tube (2) with the inner tube (4) together, so as to form a tubular element (7, 107) which has at least three metal layers, and then draw, by final drawing, the tubular element (7, 107) to obtain a compound metal wire (9) from at least three metal layers. The object of the present invention is also a semi-finished tubular element (7, 107), having at least three metal layers, which comprises an outer metal tube (2), an Inner metal tube (4) and a first binding thickness (3) interposed between the outer metal tube (2) and the inner metal tube (4).