Tin-Zinc Solder Joining Tungsten Guide Wire Cores
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Solution Overview
Problem
Conventional guide wires face challenges in securing sufficient joining strength between the core shaft and coil body, particularly when using tungsten materials, leading to potential separation during procedures and retention issues in the patient's body.
Innovation Solution
A guide wire design incorporating a core shaft and coil body joined by tin-zinc based solder, with the coil body made of tungsten and the core shaft optionally of stainless steel, utilizing tin-zinc based solder with a 91 wt.% tin and 9 wt.% zinc composition to ensure strong and manageable bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If silver-tin based solder or gold-tin based solder is used to join the core shaft and coil body, then joining strength can be achieved for some materials, but sufficient joining strength cannot be secured when the core shaft and coil body are formed of tungsten
Solution Approach 1:
The patent changes the chemical composition parameters of the solder material from conventional silver-tin or gold-tin based compositions to a specific tin-zinc-based composition with 6-12 wt% zinc content. This parameter change enables the solder to achieve adequate joining strength with tungsten materials while maintaining compatibility with stainless steel core shafts, thereby resolving the material compatibility issue.
Solution Approach 2:
The patent employs a composite solder material consisting of tin as the base metal with zinc as an alloying element (6-12 wt%). This composite material formulation creates a eutectic or near-eutectic composition that provides both wetting capability for stainless steel and bonding strength for tungsten, achieving universal applicability across different material combinations.
2Reliability
If conventional solder materials are used, then joining can be achieved for stainless steel core shafts, but the joining strength is insufficient and separation may occur during procedures
Solution Approach 1:
The patent modifies the solder composition parameters to include 6-12 wt% zinc in the tin-based solder. This specific compositional range creates optimal metallurgical bonding characteristics that ensure reliable joining strength, preventing separation during medical procedures while maintaining compatibility with both stainless steel and tungsten materials.
3Strength
If the solder melting point is too high, then strong bonding can be achieved, but the solder becomes difficult to manage during the joining process
Solution Approach 1:
The patent adjusts the melting point parameter of the solder by incorporating 6-12 wt% zinc into the tin-based composition. This creates a eutectic or near-eutectic alloy with a lowered melting point that facilitates easier handling and application during the joining process, while still achieving adequate bonding strength for the medical guide wire application.
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 guide wire achieves secure joining strength between the core shaft and coil body, preventing separation during procedures and allowing for easy management of the solder's melting point, while maintaining visibility in radiation imaging.
Implementation Method 1
the joint includes tin-zinc based solder
Data Source
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AI summary
[Problem] To provide a guide wire having secured joining strength between a core shaft and a coil body even when the material of the core shaft and the coil body is changed variously and especially when the core shaft and the coil body are formed of tungsten. [Solution to Problem] In a guide wire 1 including a core shaft 3, a coil body 5 that covers an outer periphery of the core shaft 3, and a distal end joint 13, an intermediate joint 15, and a proximal end joint 17 that join the core shaft 3 and the coil body 5, the distal end joint 13, the intermediate joint 15, and the proximal end joint 17 include tin-zinc based solder.