Low-CTE Encapsulant Composition for Power Cycling Reliability
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Solution Overview
Problem
Conventional electronic packages suffer from material fatigue-induced fractures due to inhomogeneous temperature distribution, leading to poor power cycling performance and reliability, primarily due to high thermal expansion mismatch and stiffness of encapsulant materials.
Innovation Solution
An encapsulant comprising an electrically insulating matrix material with stress-inhibiting filler particles having a low coefficient of thermal expansion (CTE) and Young modulus is used, designed to minimize thermal stress and ensure a low-stiffness property, with a specific design rule to limit the product of Young modulus and CTE mismatch below 372 GPa*ppm/K.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional encapsulant materials with high stiffness and high CTE are used, then structural strength is improved, but thermal stress and material fatigue increase leading to poor power cycling performance
Solution Approach 1:
The patent changes the material parameters of the encapsulant by incorporating filler particles with specific properties (low CTE ≤ 6 ppm/K and low Young modulus ≤ 4 GPa) to achieve both adequate strength and reduced thermal stress, resolving the contradiction between structural strength and power cycling reliability
Solution Approach 2:
The patent uses composite materials consisting of a matrix material combined with specifically selected filler particles to create an encapsulant that balances structural requirements with thermal stress reduction, enabling both strength and reliability
2Ease of manufacture
If encapsulant material with high CTE is used, then ease of manufacture is improved, but CTE mismatch with electronic component increases leading to thermal expansion stress
Solution Approach 1:
The patent modifies the CTE parameter of the encapsulant material by selecting filler particles with CTE ≤ 6 ppm/K, which reduces the CTE mismatch with electronic components while maintaining manufacturability through standard molding processes
3Stability of the object's composition
If encapsulant with high Young modulus is used, then structural rigidity is improved, but thermal stress transmission to electronic component increases
Solution Approach 1:
The patent changes the Young modulus parameter of the encapsulant by incorporating filler particles with Young modulus ≤ 4 GPa, which reduces thermal stress transmission while maintaining sufficient structural rigidity for package integrity
Solution Approach 2:
The patent employs composite materials with specifically selected filler particles to achieve an optimal balance between structural rigidity and thermal stress absorption, preventing stress transmission to the electronic component
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 encapsulant effectively reduces thermal stress, enhancing the reliability and durability of electronic packages by preventing damage during power cycling and harsh conditions, thereby improving electric reliability.
Implementation Method 1
having a value of the coefficient of thermal expansion of not more than 6 ppm/K
Implementation Method 2
having a value of the Young modulus of not more than 4 GPa
Data Source
AI summary
An encapsulant is disclosed. In one example, the encapsulant is an electronic package, wherein the encapsulant comprises an electrically insulating matrix material. Stress inhibiting filler particles, having a value of the coefficient of thermal expansion of not more than 6 ppm/K and a value of the Young modulus of not more than 4 GPa, are located in the matrix material.