TMR Sensor Package Buffer Layer for Mechanical Stress Relief
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Solution Overview
Problem
Mechanical stresses during the production and use of TMR sensors, particularly in automotive and industrial applications, lead to performance degradation and reduced longevity due to thermal incompatibilities and material shrinkage.
Innovation Solution
A sensor package with a TMR sensor chip and a buffer layer having a low modulus of elasticity, typically less than 1 GPa, made of silicone-based materials, is used to absorb mechanical stresses and protect the sensor from damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid packaging structure is used to protect the TMR sensor chip, then mechanical strength and protection are improved, but mechanical stresses and thermal incompatibilities increase causing performance degradation
Solution Approach 1:
The patent changes the mechanical parameter (modulus of elasticity) of the buffer layer to be significantly lower than that of the TMR sensor chip and packaging materials. This parameter change allows the buffer layer to deform elastically under mechanical loads, absorbing stresses without transmitting them to the sensitive sensor chip, thus resolving the contradiction between providing mechanical protection and maintaining sensor performance stability.
Solution Approach 2:
The patent introduces a buffer layer as an intermediary element between the TMR sensor chip and the rigid packaging structure. This buffer layer acts as a mechanical mediator that decouples the rigid packaging from the sensitive sensor, allowing the packaging to provide structural strength while the buffer layer absorbs and dissipates mechanical stresses, preventing them from reaching the sensor chip.
2Duration of action of stationary object
If the sensor is protected from mechanical loads, then service life is improved, but sensitivity to external forces increases leading to measurement errors
Solution Approach 1:
The patent changes the modulus of elasticity parameter of the buffer layer to be much lower than that of the sensor chip. This ensures that under normal operating mechanical loads, the buffer layer deforms elastically and does not induce significant stresses in the sensor chip, thereby maintaining measurement precision while still providing protection against extreme mechanical events that could damage the sensor.
Solution Approach 2:
The buffer layer provides beforehand cushioning by being pre-installed between the sensor chip and the packaging structure. It is designed to absorb and dissipate mechanical stresses elastically before these stresses can reach and damage the sensor chip, thus protecting the sensor's service life without interfering with its measurement capabilities during normal operation.
3Stress or pressure
If buffer layer material is made softer (lower modulus of elasticity), then mechanical stress reduction is improved, but structural stability decreases
Solution Approach 1:
The patent optimizes the modulus of elasticity parameter of the buffer layer material to fall within a specific range (0.1-10 MPa). This parameter optimization ensures the buffer layer is soft enough to effectively absorb mechanical stresses elastically, yet stable enough to maintain its structural integrity and positioning function under normal operating conditions, resolving the contradiction between stress reduction and structural stability.
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 buffer layer effectively reduces mechanical stresses, improving the accuracy and service life of TMR sensors by maintaining stability and precision under temperature fluctuations and mechanical loads.
Implementation Method 1
a buffer layer (or one or more buffer layers) with a lower modulus of elasticity than the TMR sensor chip... The buffer layer is fitted on and/or under the TMR sensor chip to reduce mechanical stresses on the TMR sensor chip
Implementation Method 2
TMR describes a change in the electrical resistance due to tunneling of electrons through a thin insulating layer between two ferromagnetic layers
Data Source
AI summary
A sensor package is proposed, including a tunneling magnetoresistance (TMR) sensor chip and a buffer layer having a modulus of elasticity of less than 1 GPa at a temperature of 20° C. The buffer layer is fitted on and/or under the TMR sensor chip.