Sensor Chip Junction Adhesive Layer Thermal Stress Management
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Solution Overview
Problem
Temperature changes cause thermal stress between the sensor chip and the adhesive layer, leading to distortion and errors in pressure detection accuracy, which are exacerbated by the viscoelastic properties of the adhesive layer and the time it takes to reach equilibrium, affecting the efficiency of pressure sensor production.
Innovation Solution
A method to measure the characteristics of the adhesive layer in a sensor chip junction structure, allowing for the selection of an adhesive layer with optimal thickness and material properties to minimize thermal stress and improve detection accuracy, using a measurement apparatus that applies a controlled shearing force to determine the adhesive layer's properties and ensure accurate pressure detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the adhesive layer thickness is increased to relax thermal stress and suppress temperature variations, then the sensor chip distortion is reduced, but the production time increases due to extended thermostatic chamber testing
Solution Approach 1:
The invention applies preliminary action by measuring adhesive layer characteristics (storage modulus, loss modulus, tan delta) before final assembly and using these measurements to predict thermal stress behavior. This allows selection of adhesive layers that will minimize distortion under temperature changes, eliminating the need for extended thermostatic chamber testing and reducing production time while maintaining reliability
Solution Approach 2:
The invention changes parameters by transitioning from empirical adhesive selection to science-based selection using viscoelastic property measurements. By quantifying adhesive characteristics (storage modulus E', loss modulus E'', tan delta) and matching them to specific temperature ranges and sensor chip materials, the system optimizes thermal stress relaxation without requiring time-consuming post-assembly temperature cycling tests
2Stability of the object's composition
If the adhesive layer thickness is increased to improve thermal stress relaxation, then the sensor output characteristic stability is improved, but the device complexity increases
Solution Approach 1:
The invention simplifies device complexity by replacing complex multi-layer adhesive configurations with a unified viscoelastic parameter-based selection approach. By measuring and matching storage modulus, loss modulus, and tan delta values to temperature ranges and sensor chip materials, the system achieves stable output characteristics without requiring complex adhesive layer designs
Solution Approach 2:
The invention substitutes mechanical trial-and-error adhesive selection and testing with a scientific measurement and calculation system. By using dynamic mechanical analysis to measure adhesive properties and applying viscoelastic theory to predict thermal stress behavior, the system replaces complex mechanical assembly iterations with precise computational prediction, reducing overall device complexity
3Measurement precision
If the adhesive layer with optimal thickness is selected to minimize thermal stress, then the pressure detection accuracy is improved, but the measurement and selection process becomes more complex
Solution Approach 1:
The invention achieves universality by creating a measurement apparatus that can evaluate multiple adhesive layer candidates simultaneously using the same viscoelastic measurement protocol. The system measures storage modulus, loss modulus, and tan delta for different adhesives and thicknesses, then uses standardized calculations to predict thermal stress performance, enabling comprehensive evaluation without proportionally increasing complexity
Solution Approach 2:
The invention replaces complex post-assembly thermal stress measurement and adjustment mechanisms with a pre-assembly viscoelastic property measurement system. By using dynamic mechanical analysis to characterize adhesives and applying viscoelastic theory to predict thermal behavior, the system achieves high measurement precision through relatively simple non-destructive testing equipment
4Reliability
If extensive thermostatic chamber testing is performed to ensure accuracy, then the reliability is improved, but the productivity decreases
Solution Approach 1:
The invention performs preliminary measurement of adhesive viscoelastic properties before assembly, allowing prediction of thermal stress behavior and elimination of the need for extensive post-assembly thermostatic chamber testing. This preliminary characterization enables direct qualification of adhesive layers, maintaining reliability while dramatically improving productivity
Solution Approach 2:
The invention creates a computational model that copies and predicts thermal stress behavior based on viscoelastic property measurements at room temperature. By using the measured storage modulus, loss modulus, and tan delta values to calculate expected thermal stress and distortion, the system replicates high-temperature performance characteristics without requiring actual high-temperature testing, thus maintaining reliability while improving production efficiency
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 reduces the deviation in detection accuracy due to temperature changes and enhances production efficiency by allowing the sensor chip to meet predetermined accuracy ranges without the need for extensive thermostatic chamber testing, improving the reliability and speed of pressure sensor manufacturing.
Implementation Method 1
the viscoelastic properties of the adhesive layer, because it takes some time for the thermal stress to reach a state of equilibrium
Implementation Method 2
a thermal stress is generated between the sensor chip and the bottom wall portion based on differences among a coefficient of linear expansion
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
In a sensor chip junction structure, if a moving distance of a tip of a press jig (56) is any of 50 µm and 30 µm, for example, a characteristic line of a load (shearing force) (N) applied to an adhesive layer (50) formed on a glass pedestal and having a thickness set in a range from 0.3 mm to 2.5 mm is either located on any of a characteristic line Lt1 (y = 1.3889x3) and a characteristic line Lt2 (y = 0.463x3) or located in a region above zero and equal to or below any of the characteristic line Lt1 and the characteristic line Lt2.