Silver-Copper Sintering Composition for Flux-Free Metal Bonding
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Solution Overview
Problem
Current silver sintering compositions face limitations in achieving stable adhesion and sintering strength on copper, gold, or silver substrates, particularly in high-temperature applications, and often require fluxing agents that leave residues, necessitating cleaning steps.
Innovation Solution
A silver sintering composition comprising at least one silver filler, a copper alloy in the range of 0.01% to 20% by weight, and a matrix component selected from a resin or solvent, which improves adhesion and sintering strength on various metal substrates without the need for fluxing agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver sintering composition is used on copper substrates, then electrical conductivity is improved, but adhesion strength deteriorates due to lack of inter-metallic bonding
Solution Approach 1:
The patent uses a composite material system consisting of silver particles (for conductivity), copper alloy particles (for adhesion), and resin matrix (for binding). This composite structure allows the silver-copper inter-metallic bonds to form on copper substrates while maintaining overall electrical conductivity and mechanical strength.
Solution Approach 2:
The copper alloy particles act as an intermediary between the silver filler and the copper substrate. During sintering, the copper alloy reacts with the copper substrate to form inter-metallic bonds, while the silver particles maintain the electrical conductivity pathway. This intermediary mechanism solves the adhesion problem without sacrificing conductivity.
2Strength
If fluxing agents are used to form inter-metallic bonds, then adhesion is improved, but harmful residues are generated requiring cleaning steps
Solution Approach 1:
The patent extracts and eliminates the fluxing agent from the sintering composition, replacing it with a flux-less sintering mechanism using copper alloy particles that form inter-metallic bonds directly during heating. This removal of harmful fluxing agents eliminates residue generation while maintaining adhesion strength.
Solution Approach 2:
The patent changes the sintering parameters and composition to enable flux-less sintering. By controlling the heating process and using specific copper alloy compositions, inter-metallic bonds form without requiring traditional fluxing agents, thus avoiding harmful residues.
3Reliability
If silver flake is used as conductive filler, then electrical conductivity is improved, but adhesion to substrate deteriorates
Solution Approach 1:
The patent creates a composite filler system combining silver particles (for conductivity) with copper alloy particles (for adhesion). The copper alloy component provides strong bonding to the substrate while the silver component maintains electrical conductivity, solving both adhesion and conductivity requirements simultaneously.
Solution Approach 2:
The patent merges the functions of conductivity (silver) and adhesion (copper alloy) into a single filler composite. By combining these two materials in specific ratios and sizes, the composition achieves both electrical conductivity and strong substrate adhesion without requiring separate functional layers.
4Strength
If resin is added to conductive composition for adhesion, then adhesion strength is improved, but thermal and electrical conductance deteriorates
Solution Approach 1:
The patent optimizes the resin content to minimal levels necessary for adhesion while maximizing the metal particle content. By carefully controlling the resin concentration and using flux-less sintering to create dense metal-to-metal contacts, the composition achieves adequate adhesion while maintaining high thermal and electrical conductance through the sintered metal network.
Solution Approach 2:
The patent uses a composite structure where the resin matrix provides minimal binding necessary for adhesion, while the continuous network of sintered silver and copper alloy particles provides the primary pathways for thermal and electrical conduction. This composite architecture minimizes resin interference with conductance while maintaining adhesion.
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 composition achieves stable sintering with enhanced adhesion and sintering strength on copper, gold, or silver substrates, eliminating the need for fluxing agents and improving thermal and electrical conductivity, while preventing voids and porosity in the cured product.
Implementation Method 1
silver sintering composition containing a copper alloy for metal bonding... capable of stably sintering on various metal substrates such as copper, gold or silver... with good adhesion and sintering strength
Implementation Method 2
transient liquid phase sintering (TLPS)... silver sintering composition... sintered product
Implementation Method 3
improving thermal and electrical conductivity
Implementation Method 4
improving thermal and electrical conductivity... create electrical and thermal conductivity between integrated circuit devices and their substrates
Data Source
AI summary
This invention relates to a silver sintering composition. In particular, the present invention relates to a silver sintering composition containing a copper alloy, which is capable of being stably sintered on various metal substrates such as copper, gold or silver with good adhesion and sintering strength.