Metallized Interposer Structure for Thermal Stability and CTE Matching
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Solution Overview
Problem
Current interconnects in electronic assemblies, such as those used in printed circuit boards, face limitations including limited thermal conductivity, poor thermal stability, and coefficient of thermal expansion (CTE) mismatch, which are particularly problematic in high-performance electronic devices with significant heat burdens.
Innovation Solution
The development of metallized substrates with a metal layer bonded to a seed layer, where the seed layer is rendered electrically conductive through mechanical polishing. This approach allows for enhanced bonding and increased electrical conductivity, addressing issues of thermal conductivity and CTE mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional interconnects are made from epoxies or tin- and/or lead-based solders, then material and processing costs are low, but thermal conductivity and thermal stability are limited
Solution Approach 1:
The patent employs a composite interconnect structure consisting of a metal layer (providing thermal conductivity and stability) bonded to a substrate through a metallized interface. This composite approach combines the advantages of metals (thermal performance) with substrate integration, resolving the contradiction between thermal stability and manufacturing cost by enabling lower-cost substrates to achieve high thermal performance through metallization techniques
2Reliability
If glass fiber epoxy substrates are used in printed circuit boards, then manufacturing is established and costs are controlled, but thermal conductivity is low and CTE mismatch occurs
Solution Approach 1:
The patent applies metallization specifically at the interconnect regions where thermal conduction is critical, rather than requiring the entire substrate to have high thermal conductivity. This localized approach improves thermal performance at the heat transfer pathways while maintaining the benefits of standard glass fiber epoxy substrates, thereby reducing CTE mismatch complexity in non-critical areas
Solution Approach 2:
The metallized substrate creates a composite structure where the metal layer provides high thermal conductivity pathways through the otherwise low-conductivity glass fiber epoxy substrate. This composite approach resolves the thermal conductivity limitation while the metal layer's CTE properties help bridge the mismatch between the substrate and high-performance electronic components
3Manufacturing precision
If silicon interposers are used for high-performance computing systems, then fine pitch density and TSV formation capabilities are achieved, but cost increases significantly
Solution Approach 1:
The patent employs cost-effective metallization techniques on standard substrates that can achieve adequate fine pitch density without requiring expensive silicon interposers. The approach uses economical metal deposition and bonding methods that provide sufficient precision for the application, resolving the contradiction by accepting good-enough precision at a fraction of the cost of silicon-based solutions
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 proposed solution significantly improves thermal conductivity and stability, while also addressing CTE mismatch issues, thereby enhancing the performance and reliability of interconnects in high-performance electronic devices.
Implementation Method 1
a seed layer directly adhered to the base substrate, the seed layer being mechanically polished
Implementation Method 2
a metal layer formed upon at least a portion of the seed layer
Data Source
AI summary
Substrates may be metallized by introducing a seed layer upon a base substrate, mechanically polishing the seed layer, and forming a metal layer upon the seed layer after mechanical polishing. The base substrate may comprise a ceramic, such as silicon nitride or aluminum nitride, a polymer, silicon, metal, or glass. The seed layer optionally may be rendered electrically conductive by mechanical polishing of an initially non-conductive seed layer. The metal layer may be formed by depositing a metal nanoparticle composition upon the seed layer after mechanical polishing and consolidating metal nanoparticles therein, such as through a hot pressing operation. The metal nanoparticle composition may contain one or more additives that facilitate CTE matching of the metal layer to the base substrate.