Multilayer Silver Sintering Film for High-Reliability Die Attachment
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Solution Overview
Problem
Conventional joining techniques for electronic components on circuit boards, such as soldering, fail to provide sufficient strength and elasticity, especially when dealing with components of different thermal expansion coefficients and under high thermal or mechanical stress.
Innovation Solution
A sintered silver film composition incorporating reinforcing graphite particles and a silver foil layer is used, which enhances the strength and elasticity of the joints by combining nanosilver powder with innovative chemical formulations, allowing for high thermal and electrical conductivity interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sintering methods are used to join silver particles, then joining is achieved, but oxidation occurs and adhesion to substrates is poor
Solution Approach 1:
The patent employs a controlled atmosphere during sintering that maintains reducing conditions to prevent oxidation of silver particles. The atmosphere is managed throughout the heating and holding phases to ensure silver remains in its metallic state, eliminating the harmful oxidation effect while achieving reliable joining.
2Area of stationary object
If thick silver films are deposited to ensure coverage, then substrate coverage is improved, but adhesion to underlying layers deteriorates
Solution Approach 1:
The patent employs a multilayer silver film structure where different layers have different thicknesses and properties. The first layer is thinner and optimized for adhesion to the underlying substrate, while subsequent layers provide additional coverage and functionality. This local differentiation of layer properties resolves the contradiction between achieving sufficient coverage and maintaining strong adhesion.
3Strength
If silver particles are sintered at high temperature to achieve joining, then joining strength is improved, but particle aggregation and loss of fine structure occur
Solution Approach 1:
The patent carefully controls sintering parameters including temperature, holding time, and atmosphere composition to achieve joining strength while preserving the fine particle structure. By optimizing these parameters within specific ranges, the process achieves sufficient bonding without causing excessive particle aggregation or sintering that would destroy the desired microstructure.
4Reliability
If multiple processing steps are used to achieve reliable joining, then joining reliability is improved, but process complexity increases
Solution Approach 1:
The patent combines multiple functions into a single integrated sintering process that simultaneously achieves particle joining, oxidation prevention, and adhesion promotion. By conducting the sintering operation in a controlled atmosphere that addresses multiple concerns at once, the process reduces the number of separate processing steps while maintaining high joining 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 sintered silver film composition significantly improves the reliability and performance of electronic devices by providing five to ten times better joint strength and elasticity compared to traditional methods, enabling the use of advanced devices like SiC and GaN with high temperature applications.
Implementation Method 1
a first layer of silver particles is sintered to a substrate
Implementation Method 2
a second layer of copper particles is diffusion bonded to the first layer of silver particles
Data Source
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AI summary
Materials for die attachment such as silver sintering films may include reinforcing, modifying particles for enhanced performance. Methods for die attachment may involve the of such materials.