Copper Alloy Lead Wire for Narrow Space Insertion

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Solution Overview

Problem

Existing lead wires for narrow space insertion, such as into ultrasonic probes or electrode catheters, face challenges in being easily inserted without breaking or bending, and require a balance between strength and slidability to avoid interference and wear during insertion.

Innovation Solution

A lead wire with a copper alloy wire of 0.015 to 0.18 mm diameter, coated with an insulating layer having a friction coefficient of 0.05 to 0.3, and a tensile strength of 700 to 1,500 MPa, ensuring easy insertion and preventing breakage or buckling, while maintaining high conductivity for low resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the lead wire is made with higher strength to prevent breakage and bending during insertion, then the tensile strength increases, but the friction coefficient increases making insertion more difficult

Engineering Contradiction:
Improvetensile strengthVSAvoidease of insertion
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The patent applies different surface treatments to different parts of the lead wire. The outer surface of the insulating layer is treated with a low-friction coating (friction coefficient 0.05-0.3) to facilitate insertion, while the copper alloy core maintains high tensile strength (700-1500 MPa) through its material composition and heat treatment. This local differentiation resolves the contradiction by optimizing each property where needed.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The lead wire uses a composite structure with a copper alloy core (providing strength) and an insulating layer with low-friction outer surface (providing ease of insertion). The copper alloy itself is a composite of Cu, Ag, and other elements, combining electrical conductivity with mechanical strength. This composite approach allows simultaneous achievement of high strength and low friction.

Inventive Principle:
Principle #40Composite materials

2Ease of operation

If the lead wire diameter is reduced to fit narrow spaces, then the insertion ease improves, but the conductivity decreases

Engineering Contradiction:
Improveease of insertionVSAvoidconductivity
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent optimizes the diameter parameter to 0.015-0.18 mm, which is sufficiently small for narrow space insertion yet large enough to maintain acceptable conductivity. Additionally, the copper alloy composition is adjusted (containing 0.5-15 mass% Ag) to enhance conductivity per unit area, compensating for the reduced diameter. The conductivity is maintained at 60-90% IACS through material composition control.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If the lead wire is made more flexible to ease insertion, then the ease of operation improves, but the tensile strength decreases leading to breakage and buckling

Engineering Contradiction:
Improveease of insertionVSAvoidtensile strength
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The insulating layer acts as a flexible shell that allows the lead wire to bend and flex during insertion without compromising the structural integrity of the copper alloy core. The insulating layer's flexibility enables easy manipulation and insertion, while the core maintains high tensile strength (700-1500 MPa) to prevent breakage and buckling.

Inventive Principle:
Principle #30Flexible shells and thin films

Data Source

PatentUS11456087B2Lead wire for narrow space insertion
Publication Date: 2022.09.27 TOTOKU ELECTRIC CO LTD

AI summary

To provide a lead wire for narrow space insertion that is easily inserted into an elongated small-diameter pipe or small-diameter tube such as an ultrasonic probe or an electrode catheter. The above-described problem is solved by a lead wire for narrow space insertion including a copper alloy wire having a conductor diameter within a range of 0.015 to 0.18 mm, and an insulating layer provided to an outer periphery of the copper alloy wire. A friction coefficient of an outermost surface layer of the insulating layer is within a range of 0.05 to 0.3, a tensile strength of the lead wire is within a range of 700 to 1,500 MPa, and a conductivity of the copper alloy wire is within a range of 60 to 90% IACS.