Semiconductor Strain Sensor Metal Bonding Stability
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Solution Overview
Problem
Conventional semiconductor strain gauges face issues with long-term stability due to resin adhesive degradation, and the rigidity of the strain sensor chip affects the uniformity of strain measurement, leading to sensitivity variations and nonlinear behavior.
Innovation Solution
A semiconductor strain sensor with a metal base plate and strain sensor chip bonded using a metal bonding material, where the strain sensor chip is attached to the object via extending members, ensuring symmetrical rigidity and preventing flexural deformation, and the ground is electrically connected to the object to minimize noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If resin adhesive is used to bond the strain sensor chip to the object, then ease of manufacture is improved, but long-term stability deteriorates due to adhesive degradation
Solution Approach 1:
The patent removes the resin adhesive layer from the bonding structure, directly bonding the strain sensor chip to the object. This extraction of the adhesive component eliminates the source of degradation while maintaining manufacturing simplicity through direct bonding techniques.
Solution Approach 2:
The patent employs a composite structure where the strain sensor chip is directly bonded to a rigid substrate, creating a stable composite assembly that eliminates the intermediate adhesive layer responsible for long-term degradation while maintaining ease of manufacture.
2Ease of operation
If the strain sensor chip has sufficient thickness for handling, then ease of operation is improved, but measurement precision deteriorates due to non-uniform strain transmission
Solution Approach 1:
The patent applies local quality by making the strain sensor chip thin only in the active measurement region where strain detection occurs, while maintaining adequate thickness in non-critical areas for handling. This localized thinning ensures uniform strain transmission to the piezoresistive element while preserving operational ease.
Solution Approach 2:
The patent addresses the thickness contradiction by transitioning to a thin-film semiconductor fabrication approach, where the chip is manufactured with precise thickness control in the micrometer range. This dimensional precision enables both easy handling and uniform strain transmission simultaneously.
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 provides stable long-term characteristics, accurate strain measurement, and reduced noise, maintaining a consistent conversion factor across the strain measuring range.
Implementation Method 1
a semiconductor strain gauge which uses, in place of the metal thin film, a semiconductor piezoresistive element formed by doping an impurity to a semiconductor such as silicon as a strain detection section. The resistance change rate for the strain of the semiconductor strain gauge is several 10 times as large as that of the strain gauge using the metal thin film
Implementation Method 2
a metal base plate 3 with a bonding area 15 to which an undersurface of the strain sensor chip 2 is bonded with a metal bonding material 4
Data Source
Figure 1~2
Figure 3A~4
Figure 5~7
AI summary
A semiconductor strain sensor having a strain sensor chip composed of a semiconductor substrate having a piezoresistive element as a strain detection section. The semiconductor strain sensor has a stable characteristic for a long period of time and a stable conversion factor of a strain generated in the strain sensor chip corresponding to a strain of an object to be measured, within a strain range of a size to be measured. The strain sensor chip is bonded to a metal base plate with a metal bonding material. The metal base plate has two or four extending members, which protrude from a side of the strain sensor chip for attaching the strain senor chip to the object to be measured. Preferably, a groove is arranged between a metal base plate undersurface area, which corresponds to the bonding area where the strain sensor chip is bonded to the metal base plate, and the undersurfaces of the extending members, and a protruding section sandwiched by the grooves is arranged on the undersurface of the metal base plate.