Superconductive Jointing Alloy for MRI Coil Encapsulation

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Solution Overview

Problem

In the production of superconducting magnets for MRI, the low melting point of Wood's metal used for soldering coil leads results in joint integrity issues during resin encapsulation, leading to waste and environmental hazards from cadmium.

Innovation Solution

A superconductive jointing alloy with a melting point higher than the encapsulation process temperature is used to couple coil leads before encapsulation, eliminating the need for post-encapsulation soldering and avoiding cadmium use.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If Wood's metal is used for soldering coil leads, then the soldering process is simple and the melting point is low, but the joint integrity deteriorates during resin encapsulation due to low melting point

Engineering Contradiction:

Improvesoldering process simplicityVSAvoidjoint integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the melting point parameter of the soldering alloy from low (Wood's metal) to high (above resin encapsulation temperature) to prevent joint melting during encapsulation while maintaining ease of manufacture

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite alloy composition (e.g., In-Sn-Bi-Pb) that combines multiple elements to achieve both high melting point and superconducting properties, resolving the contradiction between manufacturability and reliability

Inventive Principle:

Principle #40Composite materials

2Temperature

If Wood's metal is used for soldering, then the soldering temperature is low, but cadmium is present which creates environmental hazards

Engineering Contradiction:

Improvesoldering temperatureVSAvoidcadmium hazard

Core Design Contradiction:

TemperatureVSObject-generated harmful factors

Solution Approach 1:

The patent removes cadmium from the alloy composition entirely, extracting the harmful element while maintaining the low-temperature soldering advantage through alternative alloy design

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the potential harm of low melting point into a benefit by carefully selecting an alloy that melts at a temperature suitable for encapsulation without requiring excessive heat, thus avoiding cadmium while maintaining processability

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Ease of manufacture

If leads are cleaned after encapsulation to remove residual resin, then the encapsulation process is simple, but the leads become damaged causing waste

Engineering Contradiction:

Improveencapsulation process simplicityVSAvoidlead integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent performs soldering before encapsulation rather than after, taking preliminary action to join leads while they are accessible, thereby avoiding the need for post-encapsulation cleaning that causes lead damage

Inventive Principle:

Principle #10Preliminary action

4Reliability

If soldering is performed after encapsulation, then the joint can be made, but the leads must be restrained to avoid movement during magnet operation

Engineering Contradiction:

Improvejoint formationVSAvoidlead restraint requirement

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent performs soldering before encapsulation, completing the joint formation while leads are accessible and can be properly positioned, eliminating the need for complex restraint mechanisms during operation

Inventive Principle:

Principle #10Preliminary action

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 allows for encapsulation of coupled coils without damaging solder joints, maintaining joint integrity and eliminating cadmium hazards, ensuring reliable operation in MRI systems.

Implementation Method 1

The jointing alloy has a melting point higher than a highest temperature experienced by the encapsulation material during the encapsulation process. The superconductive jointing alloy may be a superconductor at low temperatures.

Methodology Applied

Scientific EffectSuperconductivity: Superconductivity

Implementation Method 2

encapsulating the first coil, the electrical circuit device and the jointed leads of the first coil and the electrical circuit device in an encapsulation material

Methodology Applied

Scientific EffectEncapsulation:

Data Source

PatentUS8307534B2Method of forming a coupled coil arrangement

Publication Date: 2012.11.13 SIEMENS HEALTHCARE LTD

AI summary

A method of forming an encapsulated coupled coil arrangement. The method includes coupling a first lead of a first coil to a second lead of an electrical circuit device, by soldering or infusion, using a superconductive jointing alloy; and encapsulating the first coil, the electrical circuit device and the jointed leads of the first coil and the electrical circuit device in an encapsulation material. The jointing alloy has a melting point higher than a highest temperature experienced by the encapsulation material having the encapsulation process.