Silver-Silicon Bonding Material for Low-Temperature Sintering Reliability

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Solution Overview

Problem

Existing low-temperature-sinterable bonding pastes require complex production processes and do not adequately address the thermal expansion mismatch between semiconductor elements and metal layers, leading to reliability issues such as cracking and breakage in thermal fatigue testing.

Innovation Solution

A low-temperature-sinterable bonding material composed of silver and silicon particles, with a high proportion of silicon atoms on the particle surfaces, forms an atomic-level interface during sintering, enhancing bonding strength and reliability while allowing for simple preparation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If silver particles are used as bonding material for high-temperature semiconductor elements, then bonding strength is improved, but thermal expansion mismatch causes cracking and breakage in thermal fatigue testing

Engineering Contradiction:

Improvebonding strengthVSAvoidthermal fatigue resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent uses a composite bonding material consisting of silver particles (for bonding strength and electrical conductivity) combined with silicon particles (for thermal expansion matching). This composite structure allows the material to simultaneously achieve strong bonding and compatibility with semiconductor thermal expansion characteristics, preventing cracking during thermal fatigue testing.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent modifies the bonding material composition by adding silicon particles with thermal expansion coefficients matching those of semiconductor elements. This parameter change in material composition enables the bonding layer to expand and contract with the semiconductor during temperature cycles, eliminating the thermal stress that causes cracking.

Inventive Principle:

Principle #35Parameter changes

2Temperature

If lead-free solder with high melting point is used for SiC chip bonding, then high-temperature operation is enabled, but such solder is difficult to obtain and process

Engineering Contradiction:

Improveoperating temperatureVSAvoidsolder availability and processing

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent replaces difficult-to-obtain high-melting-point lead-free solder with a readily available silver-silicon bonding paste. While silver has lower melting point than some high-temperature solders, the sintering process creates strong bonds that are sufficient for high-temperature operation, and the material is much easier to source and process.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent substitutes traditional soldering (melting and solidifying metal) with sintering bonding (heating to activate diffusion bonding). This mechanical/thermal process substitution allows bonding at lower temperatures than high-melting-point solders while achieving comparable or superior bond strength.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Temperature

If conventional low-temperature-sinterable bonding paste is used, then sintering at low temperature is achieved, but production process complexity increases

Engineering Contradiction:

Improvesintering temperatureVSAvoidproduction process complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent extracts only the essential functional components (silver particles for bonding and silicon particles for thermal matching) from complex conventional pastes, eliminating unnecessary additives and processing steps. This simplified composition achieves low-temperature sintering without the production complexity of conventional multi-component pastes.

Inventive Principle:

Principle #2Taking out (Extraction)

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 material enables low-temperature sintering with improved bonding strength and thermal fatigue resistance, reducing the likelihood of cracking and breakage in semiconductor devices.

Implementation Method 1

a metal paste containing nanosized particles or microsized particles of silver or copper is used as a bonding material and the bonding material is sandwiched between objects to be bonded and is heated for a predetermined time period to sinter the metal such as silver in the bonding material to bond the objects to be bonded by a metal bonding layer

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentEP4700824A1Low-temperature-sintering bonding material and bonded structure

Publication Date: 2026.02.25 DAICEL CORP

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AI summary

Provided is a low-temperature-sinterable bonding material which can be sintered at a low temperature when used for sintering bonding, which can provide a bonded structure having high reliability, and whose preparation is simple and easy. A low-temperature-sinterable bonding material according to an embodiment contains silver particles and silicon particles, greater than 50% of surfaces of the silicon particles being constituted by silicon atoms. A low-temperature-sinterable bonding material according to another embodiment contains silver particles and silicon particles, silver constituting the silver particles and silicon constituting the silicon particles forming an interface at an atomic level by sintering.