Sensor Device Partition Wall Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current semiconductor sensor device packaging techniques, such as overmoulding, apply excessive stress to pressure sensor elements due to high stiffness and thermal expansion of mould compounds, leading to signal drift and requiring complex, costly noble metal components for chemical protection, which complicates manufacturing and affects measurement accuracy, especially in harsh environments like automotive applications.
Innovation Solution
A sensor device and manufacturing method utilizing a package with separated subframe volumes and a partition wall, where the sensor element extends through the wall and is enveloped with an encapsulant material, reducing the need for multiple moulding steps and eliminating the requirement for parallel surfaces and through-holes, thus simplifying production and enhancing environmental resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If overmoulding technique is employed to contain the pressure sensor element securely within the lead frame package, then the sensor element is securely contained, but high stress is applied to the sensing element due to high stiffness and thermal expansion of the mould compound
Solution Approach 1:
The package is divided into two separate cavities (first cavity for sensor element, second cavity for circuit) separated by a partition wall. This segmentation allows independent optimization of each cavity's contents and reduces stress transmission between components, as the sensor element is contained in its own isolated space without being subjected to the rigidity constraints of a unified moulded structure.
Solution Approach 2:
The partition wall acts as an intermediary structure between the sensor element cavity and the circuit cavity. It provides mechanical separation and support while allowing the sensor element to be secured without direct contact with the rigid outer package walls, thereby reducing stress transmission to the sensing element.
2Object-affected harmful factors
If gel is used to provide chemical protection and envelop the pressure sensor element, then chemical protection is provided, but the gel adds offset to the pressure sensed and creates g-force during acceleration
Solution Approach 1:
The harmful gel medium is completely removed from the package. Instead of enveloping the sensor element in gel, the invention uses a vacuum-sealed first cavity that directly contains the sensor element without any intermediate chemical protection layer, thereby eliminating offset and g-force effects while maintaining chemical protection through the sealed cavity structure.
Solution Approach 2:
The invention replaces the permanent gel protection with a disposable-like sealed cavity approach. The first cavity is hermetically sealed to provide chemical protection, eliminating the need for gel while maintaining protection functionality. This approach provides equivalent chemical protection without the measurement interference caused by gel.
3Object-affected harmful factors
If noble metals are used for all metal components in the cavity (bond pads, fingers, bond-wires) to ensure chemical protection, then chemical resistance is improved, but the processing and resulting packaged device become complicated and relatively expensive
Solution Approach 1:
The requirement for noble metals is completely removed by extracting the sensor element and circuit into separate, hermetically sealed cavities. The first cavity is vacuum sealed to provide chemical protection, eliminating the need for noble metal components. This allows the use of standard base metals for bond pads, fingers, and bond-wires, significantly simplifying processing and reducing cost while maintaining chemical resistance.
Solution Approach 2:
The invention creates a protective environment by copying the function of noble metal chemical resistance through a different mechanism - vacuum sealing of the first cavity. Instead of relying on noble metal properties, the chemical protection is achieved through the sealed cavity structure, allowing standard metals to be used without compromising chemical resistance.
4Adaptability or versatility
If through-hole package design is used to accommodate pressure sensor port, then pressure sensing is enabled, but the package becomes poorly compatible with pressure sensor element incorporation
Solution Approach 1:
The package is segmented into two specialized cavities: the first cavity is optimized for the pressure sensor element with vacuum sealing and port access, while the second cavity accommodates the circuit. This segmentation allows the first cavity to be specifically designed for pressure sensing applications without compromising circuit integration, solving the compatibility issue of through-hole designs.
Solution Approach 2:
The invention transitions from a traditional through-hole vertical integration approach to a lateral integration approach where the sensor element extends horizontally from the first cavity through the partition wall into the second cavity. This dimensional change allows the pressure sensor port to be accessed from the package exterior while the sensor element remains properly positioned and sealed within the first cavity.
Data Source
AI summary
A method of manufacturing a sensor device (100) comprises providing (200) a package (102) having a first die-receiving subframe volume (104) separated from a second die-receiving subframe volume (106) by a partition wall (116). An elongate sensor element (120) is disposed (202) within the package (102) so as to bridge the first and second subframe volumes (104, 106) and to overlie the partition wall (116). The elongate sensor element (120) resides substantially in the first subframe volume (104) and partially in the second subframe volume (106). The elongate sensor element (120) is electrically connected within the second subframe volume (106).