Semiconductor Package with CTE-Matched Leads
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Solution Overview
Problem
Conventional semiconductor packages are prone to mechanical damage and thermal stress due to mismatched thermal expansion coefficients between the substrate and packaging materials, which limits their reliability in harsh environments.
Innovation Solution
A robust high-performance semiconductor package design featuring a double-sided substrate with integrated electrical components, a metallic case with high thermal conductivity, and mechanical leads that match the substrate's thermal expansion coefficient, providing thermal efficiency and shock resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional hardware and hard soldering paste are used to attach substrate to package, then mechanical strength is improved, but the package becomes rigid and prone to damage from mechanical shocks
Solution Approach 1:
The patent changes the mechanical properties of the bonding material from rigid (hard soldering paste) to compliant (epoxy-based underfill), allowing the substrate to remain attached while accommodating mechanical shocks and thermal expansion differences, thus improving shock resistance while maintaining bond strength
Solution Approach 2:
The patent uses a composite bonding structure combining epoxy underfill material with selective soldering, creating a hybrid attachment system that provides both mechanical strength and compliance to shock loads, resolving the contradiction between strength and shock resistance
2Temperature
If packaging materials with good thermal characteristics are used, then thermal conductivity is improved, but coefficient of thermal expansion mismatch with substrate increases
Solution Approach 1:
The patent introduces an epoxy-based underfill material as an intermediary between the substrate and package, which has thermal and mechanical properties that bridge the gap between mismatched components, allowing high thermal conductivity materials to be used while compensating for CTE differences through the compliant underfill layer
Solution Approach 2:
The patent modifies the thermal and mechanical parameters of the bonding interface by using epoxy underfill with specific thermal conductivity and CTE properties, enabling the system to tolerate CTE mismatches while maintaining effective heat transfer through the package
3Stability of the object's composition
If hardware attachments are used to secure substrate, then mechanical stability is improved, but usable area of substrate is reduced due to contact points
Solution Approach 1:
The patent removes traditional hardware attachments (screws, clips, brackets) from the package design, eliminating the need for contact points on the substrate and thereby maximizing the usable substrate area while maintaining mechanical stability through alternative means such as underfill bonding and package structure
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 design enhances thermal efficiency, reduces mechanical stress, and increases the reliability of semiconductor packages by matching thermal expansion coefficients and using lightweight, high-thermal-conductivity materials, allowing for more compact and reliable operation in extreme environments.
Implementation Method 1
a metallic case with high thermal conductivity
Implementation Method 2
mechanical leads that match the substrate's thermal expansion coefficient
Data Source
AI summary
A semiconductor package includes a suspended substrate having one or more semiconductor devices thereon, a metallic case covering the suspended substrate, the suspended substrate being supported by a plurality of mechanical leads on opposing sides of the semiconductor package, at least one of the plurality of mechanical leads having a coefficient of thermal expansion (CTE) that substantially matches a CTE of the suspended substrate, where at least one of the plurality of mechanical leads is electrically connected to the suspended substrate, and where the plurality of mechanical leads absorb mechanical shocks so as to prevent damage to the semiconductor package. The semiconductor package also includes a thermal gel between the suspended substrate and the metallic case. The suspended substrate can be a printed circuit board. The metallic case includes mounting ears for transferring heat away from the semiconductor package.