Sensor Assembly Interposer with Flexible Stress Decoupling
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Solution Overview
Problem
Existing sensor assemblies are susceptible to mechanical stress due to external forces, temperature variations, and material mismatches, leading to degradation and physical damage, and often result in increased package size, complexity, and cost.
Innovation Solution
A sensor assembly with an interposer featuring flexible structures formed by openings that decouple mechanical stress from the sensor die, connected via flexible structures to the circuit board, reducing stress transmission and allowing for a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensor die is rigidly connected to the circuit board, then mechanical stress is effectively transmitted, but the sensor die becomes susceptible to degradation and physical damage from thermal expansion mismatches and external forces
Solution Approach 1:
The interposer incorporates flexible structures (such as flexible arms or membranes) that can deform elastically under mechanical stress. These flexible elements act as shock absorbers and stress distributors, preventing concentrated stress from reaching the sensor die while maintaining the electrical and mechanical connection to the circuit board.
Solution Approach 2:
The interposer is designed with specific material properties and geometric parameters (thickness, flexibility modulus, arm dimensions) that allow it to change its mechanical response under different stress conditions. By adjusting these parameters, the interposer can adapt to thermal expansion differences and external forces without transmitting damaging stress to the sensor die.
2Reliability
If stress decoupling elements with openings are added to the interposer, then mechanical stress is reduced, but the device complexity increases
Solution Approach 1:
The interposer is segmented into multiple functional regions: rigid connection areas for the sensor die and circuit board, and flexible stress-decoupling regions with openings. This segmentation allows each region to perform its specific function optimally while keeping the overall structure manageable and manufacturable.
Solution Approach 2:
The flexible structures with openings serve multiple functions simultaneously: they provide stress decoupling, maintain electrical connectivity through the flexible arms, and can be designed to accommodate thermal expansion. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.
3Temperature
If the interposer uses materials with different coefficients of thermal expansion, then thermal stress is managed, but manufacturing precision and assembly difficulty increase
Solution Approach 1:
The interposer uses different materials with different coefficients of thermal expansion in different regions. The flexible structures are made from materials optimized for thermal compliance, while the connection areas use materials optimized for mechanical strength and electrical conductivity. This local differentiation allows thermal stress management without compromising manufacturing precision in critical areas.
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 solution effectively decouples mechanical stress from the sensor die, reducing the risk of damage and performance degradation while maintaining a compact package footprint and simplified manufacturing.
Implementation Method 1
The flexible structures are formed by portions of the interposer being partially surrounded or enclosed by the openings... Due to the flexibility of the flexible structures, the stress decoupling elements have the effect of decoupling the sensor die from mechanical stress applied to the sensor assembly
Data Source
AI summary
A sensor assembly for being mounted on a circuit board comprises an interposer with at least one opening extending between a first and a second main surface of the interposer. The interposer comprises at least two stress decoupling elements, each comprising a flexible structure formed by a respective portion of the interposer being partially enclosed by one of the at least one opening. A sensor die is connected to the flexible structures on the first main surface. At least two board connection elements are arranged on the first main surface and adapted for connecting the assembly to the circuit board.