Copper Nanoparticle-Nanowire Paste for Low-Temperature Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for copper-to-copper bonding in microelectronics require high temperature and pressure, and Sn-based solders cause reliability concerns due to aggressive reactions and brittle intermetallic compounds, limiting their application in semiconductor processes and electronics packaging.
Innovation Solution
A conductive paste comprising a mixture of copper nanoparticles and nanowires with a specific weight ratio, where the nanoparticles are fused at a low temperature to form a strong and reliable interconnection without mechanical pressure, utilizing the nanowires to enhance mechanical and electrical properties by preventing crack propagation and solvent escape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If Sn-based solder is used for joining microelectronics devices, then bonding can be achieved at low temperature (200-250°C), but aggressive reactions with copper bump and UBM cause reliability concerns and form brittle intermetallic compounds
Solution Approach 1:
The patent uses copper nanopowder as the bonding material, which is homogeneous with the copper bump and UBM (both copper-based). This homogeneous composition prevents aggressive intermetallic reactions between dissimilar metals, eliminating the reliability issues associated with Sn-based solder while maintaining low-temperature bonding capability.
Solution Approach 2:
The patent employs a composite structure of copper nanopowder with organic vehicle and binder, creating a conductive paste that combines the benefits of copper (homogeneous bonding, low reactivity) with processable material properties (printability, adhesion), enabling reliable low-temperature bonding without the harmful effects of traditional solders.
2Reliability
If copper nanopowder is used for bonding, then homogeneous joining avoids aggressive reactions, but high temperature and pressure are required to achieve reliable Cu-Cu bonding
Solution Approach 1:
The patent changes the physical state and size parameters of copper from bulk or large particles to nanopowder with specific surface area and reactivity characteristics. This parameter change enables copper-copper bonding at low temperature (200-250°C) without requiring high pressure, while maintaining homogeneous joining that avoids aggressive reactions.
Solution Approach 2:
The patent introduces an organic vehicle and binder as intermediaries that facilitate the bonding process. The organic vehicle provides a medium for nanopowder dispersion and printability, while the binder ensures adhesion to substrates and maintains structural integrity during processing, enabling low-temperature reliable bonding without direct high-temperature Cu-Cu contact.
3Reliability
If copper nanopowder is used for bonding, then homogeneous joining avoids aggressive reactions, but mechanical pressure is typically required to achieve reliable bonding
Solution Approach 1:
The patent changes the size parameter of copper from bulk or large particles to nanopowder with high surface area to volume ratio. This parameter change increases reactivity and bonding efficiency, enabling reliable Cu-Cu bonding without requiring mechanical pressure, thus simplifying the bonding process while maintaining high reliability through homogeneous joining.
4Reliability
If traditional copper bonding methods are used, then reliable bonding can be achieved, but processing costs increase and applications to semiconductor processes are limited
Solution Approach 1:
The patent replaces traditional mechanical bonding methods (requiring high pressure and temperature equipment) with a printable paste approach. The copper nanopowder formulated in organic vehicle and binder can be deposited using conventional printing techniques, substituting complex mechanical bonding systems with simpler, more cost-effective printing processes suitable for semiconductor manufacturing.
Solution Approach 2:
The patent changes the physical form of copper from bulk metal requiring mechanical processing to nanopowder with optimized surface properties. This parameter change enables the copper to be formulated into a printable paste with controlled viscosity and flow characteristics, facilitating easy application through printing methods and reducing manufacturing costs while maintaining bonding reliability.
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 copper nanoparticle-nanowire composite enables reliable and stable bonding at low temperatures, improving mechanical and electrical properties while reducing processing costs and avoiding aggressive inter-diffusion reactions, thus extending its application in various electronics joining processes.
Implementation Method 1
utilizing the nanowires to enhance mechanical and electrical properties by preventing crack propagation
Implementation Method 2
utilizing the nanowires to enhance mechanical and electrical properties by preventing crack propagation and solvent escape
Implementation Method 3
the nanoparticles are fused at a low temperature to form a strong and reliable interconnection
Data Source
Figure 1A~1D
Figure 2A
Figure 2B
AI summary
34 CONDUCTIVE PASTE, METHOD FOR FORMING AN INTERCONNECTION AND ELECTRICAL DEVICE ABSTRACT 5 According to embodiments of the present invention, a conductive paste is provided. The conductive paste has a composition including a plurality of conductive nanoparticles and a plurality of conductive nanowires, wherein a weight ratio of the plurality of conductive nanoparticles to the plurality of conductive nanowires is between about 10:1 and about 50:1. According to further embodiments of the present invention, a method for forming 10 an interconnection and an electrical device are also provided. Figure 3B