Demountable Solder Joints for Low-Resistance HTS Current Paths

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Joining superconducting current paths in high-field magnets requires low-resistance connections that can be demounted without disrupting current flow, especially in non-insulated high-temperature superconductor (HTS) structures, which are challenging due to the potential for high currents and the need for low resistance at joints.

Innovation Solution

The use of demountable solder joints with low-temperature solder between HTS channels in superconducting current paths, allowing separation of magnet components without damaging the HTS material by maintaining the integrity of the current path through the use of low-temperature solder that can be melted and separated without affecting the HTS channels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional joining methods are used for superconducting current paths, then mechanical strength is improved, but the ability to demount without disrupting current flow deteriorates

Engineering Contradiction:

Improvejoint strengthVSAvoiddemountability

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The joint is segmented into two distinct solder layers: a first solder layer providing strong mechanical bonding, and a second solder layer with lower melting point enabling demounting. This segmentation allows the joint to exhibit both strong attachment during operation and controlled separation during maintenance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the thermal parameter (melting point) of the solder material to create functional differentiation. By using a second solder layer with lower melting point than the first solder layer, the joint can be selectively melted and demounted without compromising the structural integrity provided by the first solder layer during normal operation.

Inventive Principle:

Principle #35Parameter changes

2Power

If high current capacity is achieved in superconducting joints, then electrical performance is improved, but resistance to heat generation worsens

Engineering Contradiction:

Improvecurrent capacityVSAvoidheat generation

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The joint uses a composite solder structure with two different materials having complementary properties. The first solder layer provides mechanical strength and electrical conductivity, while the second solder layer with lower melting point acts as a thermal fuse, protecting the joint from excessive heat generation by melting before the superconductor is damaged.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The second solder layer serves as a pre-positioned thermal protection mechanism. It is designed to melt at a lower temperature than the superconducting material, providing beforehand cushioning against thermal runaway or excessive heat generation during high current operation, thus protecting the joint from harmful thermal effects.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of repair

If demountable joints are used for maintenance, then ease of repair is improved, but joint reliability deteriorates

Engineering Contradiction:

ImprovemaintainabilityVSAvoidjoint reliability

Core Design Contradiction:

Ease of repairVSReliability

Solution Approach 1:

The joint is segmented into a permanent bonding layer (first solder) and a sacrificial demounting layer (second solder). This segmentation allows the joint to maintain high reliability during operation through the strong first solder layer, while enabling easy repair by melting only the second layer for controlled disassembly without damaging the superconducting components.

Inventive Principle:

Principle #1Segmentation

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

Enables the disassembly of superconducting magnets while preserving the HTS material and maintaining low resistance in the current path, facilitating maintenance and reconfiguration of high-field magnets used in applications like MRI machines and fusion reactors.

Implementation Method 1

The use of demountable solder joints with low-temperature solder between HTS channels in superconducting current paths

Methodology Applied

Scientific EffectSoldering: Soldering

Implementation Method 2

low-temperature solder that can be melted and separated without affecting the HTS channels

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 3

Superconductors are materials that have no electrical resistance to current (are 'superconducting') below some critical temperature

Methodology Applied

Scientific EffectSuperconductivity: Superconductivity

Data Source

PatentEP4128290B1Demountable solder joints for coupling superconducting current paths

Publication Date: 2025.10.22 MASSACHUSETTS INST OF TECH

Figure 1A
Figure 1B
Figure 2A

AI summary

Described are concepts directed toward systems, structures and techniques to create low-resistance, high current capacity, demountable solder joint connections. Such systems, structures and techniques may be used to simultaneously create low-resistance, high current capacity, demountable solder joint connections at multiple locations between no insulation (NI) superconductors and in particular between NI high temperature superconductors (HTS) such as may be used in NI-HTS magnets.