Supercooled Micro-Capsule Solder Paste for Lower-Temperature Joining

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Solution Overview

Problem

The high temperatures required for melting metal alloys in soldering can damage electronic components and substrates, and lead to decreased reliability due to excessive intermetallic compound formation and diffusion.

Innovation Solution

A solder material comprising supercooled micro-capsules with a metallic core in a liquid state below its solidification temperature, alloyed metallic particles, and a flux, which allows for soldering at lower temperatures by forming a new alloy with a higher melting temperature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If high temperature is used to melt metal alloys for soldering, then the soldering process can be completed, but damage to electronic components and substrates occurs

Engineering Contradiction:

Improvesoldering temperatureVSAvoiddamage to components and substrates

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent changes the temperature parameter by using supercooled liquid metal cores that remain liquid below their solidification temperature, enabling soldering at temperatures 30-50°C lower than conventional processes. This parameter change directly reduces thermal damage to components and substrates while maintaining effective soldering

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite solder material system consisting of supercooled micro-capsules containing liquid metal cores, alloyed metallic particles, and flux. This composite structure enables low-temperature soldering by combining materials with different thermal properties, where the supercooled liquid core provides流动性 at lower temperatures without damaging components

Inventive Principle:

Principle #40Composite materials

2Reliability

If high temperature is used for soldering, then the metal alloy melts and forms joints, but excessive intermetallic compound formation occurs

Engineering Contradiction:

Improvesolder joint reliabilityVSAvoidexcessive intermetallic compound formation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the temperature parameter to below the solidification temperature of the supercooled liquid metal core, which suppresses excessive intermetallic compound formation. The lower processing temperature reduces atomic diffusion rates, preventing excessive IMC growth while still enabling effective solder joint formation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes phase transition properties of supercooled liquids, where the liquid metal core remains in liquid state below its normal solidification temperature. This phase state allows the material to flow and form joints at lower temperatures, reducing harmful phase transformations and intermetallic compound formation that occur at higher temperatures

Inventive Principle:

Principle #36Phase transitions

3Reliability

If high temperature is used for soldering, then the soldering process completes, but excessive diffusion of metallization layers occurs

Engineering Contradiction:

Improvesolder joint reliabilityVSAvoidexcessive diffusion of metallization layers

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent reduces the processing temperature parameter to below the solidification temperature of the supercooled liquid metal core. This temperature reduction decreases the diffusion coefficient of metallization layers, preventing excessive diffusion while still allowing complete soldering process to occur

Inventive Principle:

Principle #35Parameter changes

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 soldering operations at temperatures 30°C below the melting temperature of the alloy, reducing damage to components and substrates, and minimizing intermetallic compound formation and diffusion, thereby improving solder joint reliability.

Implementation Method 1

a plurality of supercooled micro-capsules each including a metallic core in a liquid state at a temperature below a solidification temperature of the metallic core

Methodology Applied

Scientific EffectSupercooling: Supercooling

Implementation Method 2

A dissolution of at least a portion of the metallic shells of the plurality of supercooled micro-capsules causes at least partial dissolution of the plurality of alloyed metallic particles, forming a resulting alloy

Methodology Applied

Scientific EffectDissolution:

Implementation Method 3

the dissolution occurs at a temperature above a melting temperature of the plurality of alloyed particles

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentUS12208471B2Solder materials including supercooled micro-capsules and alloyed particles

Publication Date: 2025.01.28 INDIUM CORP

AI summary

A material includes a plurality of supercooled micro-capsules each including a metallic core in a liquid state at a temperature below a solidification temperature of the metallic core and further includes a metallic shell surrounding each respective metallic core. A plurality of alloyed metallic particles and flux are mixed with the plurality of supercooled micro-capsules to form a solder paste. Upon heating the solder paste, the plurality of alloyed particles melt. As the metallic shells destabilize, the liquid metallic cores interdiffuse with the melted alloyed particles forming a new alloy that has a higher melting temperature than the melting temperature of the alloyed metallic particles.