Metallic Adhesive Composition for Void-Free Thermal Die Attach
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Solution Overview
Problem
Current electrically and thermally conductive materials for electronic devices face challenges such as thermal instability, void formation, and high solvent content, leading to reduced conductivity and increased environmental hazards, particularly in the context of semiconductor die attachment and thermal management in electronic devices.
Innovation Solution
A composition of metal powders and a fluxing vehicle, where lead-free metal alloy particles react to form a metallurgically interconnected network with a high volume fraction of metal and minimal voids, eliminating the need for additional diluents and chemical additives, and featuring a fluxing vehicle that evaporates to minimize residual organic content and ensure stable thermal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional conductive materials (solders, nano-sintering pastes, conductive adhesives) are used for semiconductor die attachment, then electrical and thermal connections can be established, but thermal stability is poor, voids form during processing, and additional diluents/additives are required which reduce conductivity and increase environmental hazards
Solution Approach 1:
The invention extracts and eliminates the harmful components (volatile solvents, additional diluents, and chemical additives) from the paste formulation. By using a minimal formulation consisting only of metal powders and a fluxing vehicle, the patent removes the sources of void formation and environmental hazards while maintaining the necessary functionality for die attachment and thermal management
Solution Approach 2:
The invention creates a composite material system where metal powders (including conductive metals and lead-free solder alloys) are combined with a fluxing vehicle to form a metallurgically interconnected network. This composite structure achieves both electrical/thermal conductivity and thermal stability while minimizing voids through the specific composition and processing approach
2Ease of operation
If solvent-based formulations are used to maintain paste liquidity and work life, then the paste can be processed easily, but solvent bleed-out occurs limiting applicability in tight-pitch applications and high void-content results as solvent is removed during thermal processing
Solution Approach 1:
The invention changes the formulation parameters by using a minimal composition with only metal powders and fluxing vehicle, eliminating the need for volatile solvents. This parameter change maintains paste processability through the fluxing vehicle while preventing solvent bleed-out and void formation during thermal processing
Solution Approach 2:
The fluxing vehicle serves as a temporary, consumable component that facilitates paste application and processing but is designed to be completely removed or consumed during thermal processing without leaving harmful residues. The fluxing vehicle enables easy handling during application but disappears during processing, leaving only the metallurgically bonded metal structure
3Manufacturing precision
If liquid resin is incorporated into the binder chemistry to fill voids after solvent removal, then void content is reduced, but resin rich areas form which reduce the overall effectiveness of the thermal path
Solution Approach 1:
The invention extracts and eliminates liquid resin from the formulation entirely. By removing this component, the patent prevents the formation of resin-rich areas that would compromise thermal conductivity, while still achieving void-free bonding through the metallurgical reaction mechanism enabled by the fluxing vehicle
4Reliability
If high metal loading is achieved to improve conductivity, then electrical and thermal performance is enhanced, but the paste becomes difficult to process and apply without additional diluents
Solution Approach 1:
The fluxing vehicle acts as an intermediary substance that enables high metal loading pastes to remain processable during application. It provides the necessary liquidity and work life for easy handling and deposition, while being completely consumed during thermal processing to leave only the high-metal-content bonded structure with superior conductivity
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 solution provides superior mechanical, electrical, and thermal interconnection performance with reduced voids and solvent content, maintaining conductivity and stability even under reflow conditions, thus addressing the limitations of existing materials in semiconductor die attachment and thermal management.
Implementation Method 1
featuring a fluxing vehicle that evaporates to minimize residual organic content and ensure stable thermal performance
Implementation Method 2
lead-free metal alloy particles react to form a metallurgically interconnected network with a high volume fraction of metal
Implementation Method 3
Metallic transient liquid phase sintering compositions containing blended formulations of metals and metal alloys
Data Source
Figure 1~2
AI summary
Thermally conductive adhesive materials having a first metallic component with a high melting point metal; a second metallic component having a low melting point metal; a fatty acid, an optional amine, an optional triglyceride and optional additives. Also provided are methods of making the same and uses thereof for adhering electronic components to substrates.