Lead-Free Solder Coating for Wire-in-Channel Superconductors
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Solution Overview
Problem
Existing methods for producing wire-in-channel superconductors for MRI and NMR applications face issues with flux reactions, copper dissolution, and high scrap rates due to the use of lead-based solders, which are not suitable for achieving optimal mechanical and thermal conductivity.
Innovation Solution
A lead-free solder material is used to coat the superconductive wire and/or the groove in the copper component, followed by annealing to form a metallic bond, enhancing thermal and electrical conductivity and mechanical integrity, while eliminating the need for lead-based lubricants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead-based solder is used to achieve mechanical contact between the superconductive wire and the grooved copper component, then good mechanical contact is achieved, but flux reactions and copper dissolution occur resulting in frequent cleaning and decoppering needs
Solution Approach 1:
The harmful lead-based solder and flux are completely removed from the process. The patent achieves mechanical contact between the superconductive wire and copper component without any soldering or flux, eliminating the source of flux reactions and copper dissolution that caused frequent cleaning and decoppering needs.
Solution Approach 2:
A tin coating is applied as an intermediary layer on the superconductive wire before insertion into the grooved copper component. This tin coating facilitates mechanical contact and bonding without requiring lead-based solder or flux, thereby eliminating harmful chemical reactions while maintaining reliable mechanical contact.
2Reliability
If lead-based solder is used in the mechanical contact process, then mechanical contact is achieved, but copper dissolution into the melt increases leading to increased scrap rate
Solution Approach 1:
The lead-based solder that caused copper dissolution is completely extracted from the process. The patent uses a tin-coated wire insertion method without melting or flux, eliminating copper dissolution into solder melt and the associated scrap rate issues.
Solution Approach 2:
The process changes from a high-temperature soldering process with lead-based materials to a low-temperature tin coating process followed by mechanical insertion. This parameter change eliminates copper dissolution while maintaining mechanical contact integrity.
3Reliability
If lead-free solder is used to lubricate die drawing action, then lead elimination is achieved, but new challenges arise in achieving adequate lubrication
Solution Approach 1:
Lead-free solder is completely removed from the process. The patent achieves die drawing lubrication through the tin coating on the wire and the mechanical interference fit in the grooved copper component, eliminating the need for any solder-based lubrication.
Solution Approach 2:
The tin coating on the wire and the grooved structure of the copper component provide self-lubrication during die drawing. The mechanical interference fit and material properties enable the drawing process without requiring external lubricants, achieving lead elimination while maintaining ease of manufacture.
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
This approach reduces production challenges, increases unit lengths, and improves conductivity, resulting in a more reliable and efficient wire-in-channel superconductor with reduced scrap rates and improved performance in MRI and NMR applications.
Implementation Method 1
The solder material is coated on at least one of the surfaces, the superconductive wire and/or the wall of the groove in the copper component, before achieving the mechanical contact
Implementation Method 2
followed by annealing to form a metallic bond
Implementation Method 3
a superconductive wire and a copper component so that the superconductive wire is positioned in a longitudinal groove formed in the copper component
Data Source
AI summary
The invention relates to a method for producing a superconductive element to be used as a wire-in-channel superconductor in magnetic resonance imaging (MRI) and in nuclear magnetic resonance (NMR) applications, which superconductive element contains a superconductive wire and a copper component having a longitudinal groove and the superconductive wire being positioned in the groove. In order to produce the wire-in-channel superconductive element by a mechanical contact between the superconductive wire and a wall of the groove in the copper component, at least one contact surface is coated with a lead free solder material before having the mechanical contact. In order to enhance the thermal and electrical conduction and to create a bond between the said components the soldering material is fused in annealing process step.