Ceramic Capsule Pressure Sensor Thermal Expansion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing pressure difference sensors face challenges in construction and thermal expansion mismatch between semiconductor transducer cores and metal housings, leading to cross-sensitivities and limited loadability with static pressures, particularly due to differences in thermal expansion coefficients between silicon and stainless steel or glass materials.
Innovation Solution
A pressure difference transducer with a ceramic capsule body and a semiconductor transducer core, where the measuring membrane is connected to support bodies with pressure inlet openings, and pressure-bearing joints made of glass, ensuring thermal expansion compatibility and isostatic pressure supply through ducts and capillary lines, allowing for precise measurement of pressure differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a semiconductor transducer core is mounted directly in a metal housing, then the device structure is simplified, but thermal expansion mismatch causes mechanical stress and measurement errors
Solution Approach 1:
A ceramic socket is introduced as an intermediary component between the semiconductor transducer core and the metal housing. The ceramic material serves as a thermal expansion buffer that accommodates the differential expansion between silicon (3×10^-6/K) and stainless steel (10-16×10^-6/K), preventing mechanical stress and measurement errors while maintaining structural integrity
Solution Approach 2:
The device employs a composite structure combining ceramic and metal materials in the housing assembly. The ceramic portion provides thermal expansion compatibility with the semiconductor core, while the metal portion provides structural strength, creating a functionally optimized composite housing system
2Reliability
If a decoupling body with adhesive or soldering is used to mount the transducer core, then thermal expansion mismatch is accommodated, but construction and joining technology complexity increases
Solution Approach 1:
The ceramic socket acts as a pre-fabricated intermediary component that integrates the thermal expansion accommodation function into a single manufacturable part. This eliminates the need for complex adhesive bonding or soldering processes, as the ceramic socket can be mechanically assembled into the metal housing with standard joining techniques
Solution Approach 2:
The housing is segmented into distinct ceramic and metal components, with the ceramic socket forming a separate assembly that houses the transducer core. This segmentation allows each material to be optimized and manufactured independently, then assembled together, simplifying the overall construction process
3Ease of manufacture
If a glass support is used for the transducer core, then manufacturing is simplified, but cross-sensitivities to static pressure occur due to lower compression modulus
Solution Approach 1:
The solution uses a composite housing structure where the ceramic portion provides the necessary mechanical support with appropriate compression modulus, avoiding the cross-sensitivity issues of glass while maintaining manufacturing simplicity. The ceramic material offers optimal mechanical properties for pressure sensor applications
4Reliability
If elastic seals are used to softly seat the silicon chip, then thermal expansion is accommodated, but minimum volume is required reducing compactness
Solution Approach 1:
The ceramic socket provides rigid support with controlled thermal expansion properties, eliminating the need for bulky elastic seals. The ceramic material's inherent mechanical and thermal properties allow for a compact design while maintaining reliable thermal expansion accommodation
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 mitigates thermal expansion issues and enhances loadability by maintaining accurate pressure difference measurements while minimizing mechanical stress, ensuring reliable operation across varying temperature conditions.
Implementation Method 1
a pressure-bearing joint, which surrounds the first pressure inlet opening pressure-tightly, surrounds the opening of the first duct into the transducer seat, and is connected pressure-tightly with a wall of the transducer seat
Implementation Method 2
the transducer cores comprise especially piezoresistive or capacitive transducers, in order to transduce a pressure difference dependent deflection of a measuring membrane of the transducer core into an electrical signal
Implementation Method 3
the transducer cores comprise especially piezoresistive or capacitive transducers, in order to transduce a pressure difference dependent deflection of a measuring membrane of the transducer core into an electrical signal
Implementation Method 4
the coefficient of thermal expansion of silicon, an established material for semiconductor pressure measuring transducers, amounts to about 3×10^-6/K, while the coefficient of thermal expansion for the here relevant stainless steels lies between 10 and 16×10^-6/K
Data Source
AI summary
A pressure difference sensor includes a capsule, which has a ceramic capsule body. The capsule has a transducer seat in its interior, wherein there is arranged in the transducer seat a semiconductor pressure measuring transducer core, which has a measuring membrane body and at least one support body. The measuring membrane body is connected pressure-tightly with the at least one support body, which has a pressure inlet opening. Ducts extend respectively from an outer surface of the capsule into the transducer seat, wherein the pressure inlet opening communicates with the first duct A side of the measuring membrane is contactable with a pressure through the pressure inlet opening, wherein the support body contacts a joint, which surrounds the first pressure inlet opening and the opening of the first duct into the transducer seat and is connected pressure-tightly with a wall of the transducer seat, and wherein a second side of the measuring membrane is hydraulically isolated from its first side and communicates with the second duct.