Nanoparticle Sintered Interconnects for Low-Temperature Pressureless Bonding
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Solution Overview
Problem
Current sintering methods for interconnecting electronic components are inadequate, particularly for components sensitive to temperature and high thermal inertia, as they require high temperatures and can damage sensitive components, and existing sintering pastes often necessitate pressure that may also cause damage.
Innovation Solution
A method involving a sintering solution with metal nanoparticles, primarily silver, gold, or copper, in a polyhedral shape with an aspect ratio greater than 0.8, dispersed in a solvent with a stabilizing agent, which forms an ordered agglomerate upon solvent elimination and debinding, allowing sintering at lower temperatures without pressure, resulting in a dense interconnection layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sintering methods are used to interconnect electronic components, then electrical and thermal conductivity are improved, but temperature sensitivity of components deteriorates due to high sintering temperatures (200-300°C)
Solution Approach 1:
The invention changes the particle size parameter of the sintering paste from conventional micrometric particles to nanometric particles (less than 100 nm). This parameter change enables sintering at lower temperatures because nanometric particles have higher surface energy and reactivity, allowing them to sinter between themselves at temperatures well below the fusion temperature of solid silver (961°C), thus resolving the contradiction between achieving good conductivity and protecting temperature-sensitive components
Solution Approach 2:
The invention uses a composite sintering paste formulation containing both nanometric particles (less than 100 nm) and micrometric particles. This composite structure combines the benefits of nanometric particles (high reactivity, low sintering temperature) with micrometric particles (structural stability), enabling effective low-temperature sintering while maintaining mechanical integrity and electrical/thermal conductivity
2Object-affected harmful factors
If pressure is applied to reduce sintering temperature, then temperature sensitivity is protected, but component damage occurs due to mechanical stress
Solution Approach 1:
The invention changes the particle size parameter to nanometric scale, which fundamentally alters the sintering mechanism. Nanometric particles sinter through surface diffusion and grain boundary migration at lower temperatures without requiring high pressure, thus protecting both temperature-sensitive components and mechanically fragile components from damage
3Temperature
If sintering paste with nanometric particles is used, then sintering temperature is reduced, but manufacturing complexity increases due to particle agglomeration and paste formulation
Solution Approach 1:
The invention introduces organic vehicles and binding agents as intermediaries in the sintering paste formulation. These intermediaries disperse the nanometric particles uniformly, prevent agglomeration during storage and application, and facilitate controlled sintering. The organic matrix acts as a mediator that manages the complexity of handling nanometric particles while enabling low-temperature sintering
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 achieves a dense sintered interconnection layer with improved electrical and thermal conductivity, suitable for sensitive components, by facilitating coalescence at lower temperatures and eliminating the need for pressure, thus enhancing the feasibility of connecting components without damaging them.
Implementation Method 1
A sintering paste of this type generally comprises 90% by weight of particles of silver... Sintering a sintering paste based on silver is also a known technique for interconnecting electronic components
Implementation Method 2
facilitating coalescence at lower temperatures... the stabilizing agent binding them together and maintaining at least a portion of the metal nanoparticles at a distance from each other
Implementation Method 3
at least partially eliminating the solvent from the interconnection layer such as to form at least one ordered agglomerate
Implementation Method 4
a sintered silver interconnection layer may have an electrical conductivity of more than 20×106 S·m−1
Implementation Method 5
a sintered silver interconnection layer may have... a thermal conductivity of the order of 200 W·m−1·K−1
Data Source
AI summary
A method for interconnecting components of an electronic system includes depositing a sintering solution onto a first component to form an interconnection layer, the sintering solution comprising a solvent, metal nanoparticles dispersed in the solvent, and a stabilizing agent adsorbed onto the nanoparticles. More than 95.0%, preferably more than 99.0% of the mass of the nanoparticles include a metal selected from silver, gold, copper and alloys thereof and have a polyhedral shape with an aspect ratio greater than 0.8. The method also includes eliminating, at least partially, the solvent from the layer to form an ordered agglomerate in which the nanoparticles are regularly disposed in three axes, the stabilizing agent binding them together and maintaining at least a portion of the nanoparticles at a distance from each other, debinding and sintering the layer, and depositing a second component in contact with the layer before or during debinding or sintering.