Organic-Inorganic Hybrid Polymer Interlayer for Thermal Stress Reduction
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Solution Overview
Problem
Integrated circuits and sensors face thermal stress issues due to material mismatch, leading to delamination, buckling, and signal drift, especially in environments with temperature fluctuations, which existing stress-relief methods like PI coating or complex shaping of metal sheets fail to adequately address.
Innovation Solution
A method involving molecular layer deposition of an organic-inorganic hybrid polymer interlayer, such as alucone, is used to buffer thermal stresses between components with different coefficients of thermal expansion, providing a conformal and flexible buffer that reduces direct contact and stress between materials like metal and semiconductor components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If materials with different physical properties are placed in contact to form packaged integrated circuits, then device functionality is achieved, but thermal stress and delamination occur in aggressive environments
Solution Approach 1:
A polymeric stress reduction layer is introduced between the semiconductor die and the molding compound to act as an intermediary that reduces thermal stress. This layer has mechanical properties intermediate between the rigid semiconductor die and the molding compound, preventing direct stress transmission and eliminating delamination while maintaining device functionality.
2Stress or pressure
If PI coating is applied on top of stressed structures to reduce thermal stress, then stress relief is achieved, but attachment issues worsen sensor performance and lead to signal drift
Solution Approach 1:
Instead of applying PI coating on top of the device, the stress reduction function is copied to the interface between the semiconductor die and molding compound by forming a polymeric stress reduction layer during the packaging process itself. This eliminates the need for additional top-layer coatings that cause attachment issues, while maintaining stress relief functionality.
3Stress or pressure
If slots are introduced on metal sheets to reduce stress, then thermal stress is reduced, but manufacturing complexity increases
Solution Approach 1:
Instead of modifying the geometric shape of metal sheets by introducing slots, the solution changes the material parameter by introducing a polymeric stress reduction layer with appropriate mechanical properties. This layer absorbs thermal stress through its viscoelastic properties, achieving stress reduction without altering the fundamental geometry or increasing manufacturing complexity of the metal components.
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 effectively reduces thermal stress and delamination, maintaining signal integrity and device performance over the lifetime of sensors by providing a flexible, thin interlayer that can be integrated into existing manufacturing processes, enhancing thermal resilience and reducing signal drift.
Implementation Method 1
providing an interlayer by molecular layer deposition of a third material, being an organic-inorganic hybrid polymer compound
Implementation Method 2
the first material may have a predetermined first value of coefficient of thermal expansion (CTE), the material of the second component (provided over the first component) is a second material with a predetermined second value of CTE different from the first value
Data Source
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AI summary
The present invention provides a sensor and method for manufacturing the sensor including a first component comprising a first material with a predetermined first value of coefficient of thermal expansion (CTE), a second component over the first component, the second component comprising a second material with a predetermined second value of CTE different from the first value. An interlayer is provided by molecular layer deposition, for minimizing stress caused by coefficient of thermal expansion mismatch between the first and second components. The interlayer includes an organic-inorganic hybrid polymer compound.