Inter-diffusion Layer Bonding for High-Temperature Die Attach
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Solution Overview
Problem
Current high-temperature die attach materials for electronic applications, such as those in deep oil exploration, aerospace, and automotive, face challenges with lead content toxicity, reliability degradation at high temperatures, and lengthy testing times, necessitating lead-free, thermally stable solutions that maintain strength over extended periods.
Innovation Solution
A method involving the formation of contiguous inter-diffusion layers between a substrate and a semiconductor die using a filler material like sintered silver nanoparticles, which creates a strong, thermally and electrically conductive bond without requiring the melting point of the materials or high processing temperatures, and allows for controlled porosity and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If lead-containing high-temperature die attach materials are used, then thermal stability and high-temperature strength are improved, but environmental hazards and toxicity increase
Solution Approach 1:
The invention extracts and eliminates lead from the die attach material composition entirely, replacing it with lead-free intermetallic compounds such as Cu6Sn5 and Cu3Sn that can provide equivalent or superior high-temperature stability without the harmful effects of lead
Solution Approach 2:
The invention uses composite intermetallic structures formed by diffusion between copper substrate and tin-containing die attach materials, creating a multi-phase composite material system that achieves high-temperature stability through the synergistic combination of different intermetallic phases rather than relying on lead
2Strength
If conventional high-temperature die attach materials are used, then initial bonding strength is achieved, but reliability deteriorates during high-temperature storage
Solution Approach 1:
The invention performs preliminary formation of a controlled intermetallic layer structure before final die attach operation, creating a pre-stabilized diffusion barrier that prevents subsequent degradation during high-temperature storage. The Cu6Sn5 intermetallic layer is formed in advance as a stable interface structure
Solution Approach 2:
The invention changes the chemical composition parameters of the die attach material to contain specific amounts of tin (e.g., 2-10 wt%) that will diffuse during bonding to form optimal intermetallic structures, and adjusts processing temperature and time parameters to control the extent of diffusion and achieve the desired intermetallic phase distribution
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
This approach provides a lead-free, reliable, and environmentally friendly high-temperature die attach solution that strengthens over time, maintains mechanical and thermal integrity, and allows for controlled thermal and electrical conductivity, suitable for large die sizes and extreme environments.
Implementation Method 1
heating the filler material to facilitate formation of a plurality of inter-diffusion layers. Due to the heating, a first inter-diffusion layer may be formed between the filler material and the first object. Further, a second inter-diffusion layer may be formed between the filler material and the second object
Data Source
AI summary
The present disclosure provides a method of creating a bond between a first object and a second object. For example, creating a joint or die attach between a semiconductor chip and an electronic substrate, especially for harsh and high temperature environments. The method may include a step of filling a space between the first object and the second object with a filler material. Further, the method may include a step of heating the filler material to facilitate formation of a plurality of inter-diffusion layers. Accordingly, a first inter-diffusion layer may be formed between the filler material and the first object. Further, a second inter-diffusion layer may be formed between the filler material and the second object. Furthermore, in some embodiments, the first inter-diffusion layer may be contiguous with the second inter-diffusion layer. The contiguity may be facilitated by placement of at least one insert between the first object and the second object, in which the inter-diffusion of the filler material and the at least one insert may produce the third inter-diffusion layer, wherein the third inter-diffusion layer is contiguous with each of the first inter-diffusion layer and the second inter-diffusion layer.