Thermoconductive Adhesive Sheet With Aggregated Silver Particles
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Solution Overview
Problem
Current sheet materials with high thermal conductivity are unreliable in hot-cold cycle tests and require sintering temperatures above 250°C, which can damage organic substrates, while materials with nano-size silver particles excel in low-temperature sintering but are problematic in adhesiveness, and those with micro-size particles are poor in sheet performance.
Innovation Solution
A thermoconductive adhesive sheet composed of secondary silver particles formed through aggregation of primary particles with average sizes between 10-100 nm, combined with a thermosetting resin and binder resin, which allows for high thermal conductivity and improved adhesiveness under low-temperature sintering conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sheet material is designed to express thermal conductivity like solder material, then thermal conductivity is improved, but reliability characteristics in hot-cold cycle test worsen
Solution Approach 1:
The patent uses a composite material structure combining micro-size silver particles (5-20 μm) with nano-size silver particles (10-100 nm) in specific proportions (micro-size: 30-90 wt%, nano-size: 10-70 wt%). This composite structure allows the micro-size particles to provide structural stability and reliability while the nano-size particles fill gaps and enhance thermal conductivity, resolving the contradiction between thermal conductivity and reliability in hot-cold cycle tests.
2Temperature
If sintering temperature is increased to 250°C or higher to express high thermal conductivity, then thermal conductivity is improved, but damage to organic substrates and oxidation of copper substrates occurs
Solution Approach 1:
The patent changes the particle size parameters of silver particles, specifically using a bimodal distribution with micro-size (5-20 μm) and nano-size (10-100 nm) particles. This parameter change enables effective sintering at lower temperatures (200°C or lower) because the nano-size particles provide high surface area and reactivity for sintering, while the micro-size particles maintain structural integrity, thus achieving high thermal conductivity without damaging organic substrates or oxidizing copper substrates.
3Temperature
If nano-size silver particles are used for low-temperature sintering, then sintering temperature is reduced, but temporary adhesiveness deteriorates
Solution Approach 1:
The patent creates a composite particle system where micro-size silver particles (5-20 μm) serve as the primary adhesive component providing temporary adhesiveness, while nano-size silver particles (10-100 nm) act as fillers that enhance sintering activity. The micro-size particles maintain mechanical strength and adhesiveness, while the nano-size particles enable low-temperature sintering through their high surface area and reactivity, thus resolving the contradiction between low-temperature sintering and temporary adhesiveness.
4Strength
If micro-size silver particles are used, then temporary adhesiveness is improved, but sheet performance deteriorates
Solution Approach 1:
The patent employs a composite particle system combining micro-size silver particles (5-20 μm) with nano-size silver particles (10-100 nm). The micro-size particles provide temporary adhesiveness and structural framework, while the nano-size particles fill interstitial spaces, enhance thermal conductivity, and improve overall sheet performance through better particle packing and reduced voids. This synergistic composite structure resolves the contradiction between temporary adhesiveness and sheet performance.
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 sheet material achieves excellent temporary adhesiveness and sheet performance with high thermal conductivity, enhancing the reliability of semiconductor devices even under low-temperature sintering conditions.
Implementation Method 1
a thermoconductive adhesive sheet which is sheet-like formed of a resin composition containing (A) silver particles, (B) a thermosetting resin, and (C) a binder resin
Implementation Method 2
the silver particles (A) are secondary particles formed through aggregation of particles that contain primary particles having an average particle size of 10 to 100 nm
Data Source
AI summary
A thermoconductive adhesive sheet which is sheet-like formed of a resin composition containing (A) silver particles, (B) a thermosetting resin, and (C) a binder resin, and in which: the silver particles (A) are secondary particles formed through aggregation of particles that contain primary particles having an average particle size of 10 to 100 nm.