Sensor Die Backside Contact Header for Fluid Measurement
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Solution Overview
Problem
Conventional fluid sensing devices experience significant piezo resistive effects due to bending or stressing under high pressure or variable pressure environments, leading to inaccurate readings, as they have a cavity between the sensor die and the header that allows for such deformation.
Innovation Solution
The sensor die is attached to a header with electrically conductive pads on both surfaces, eliminating the cavity and providing increased mechanical support by ensuring the backside of the sensor die contacts the header directly, thus reducing bending and flexing. Electrically conductive pins extend through the sensor die to connect with doped regions near the sensing element, and the header's pads contact the sensor die's pads for electrical coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cavity is left between the sensor die and the header to enable good fluid flow to the sensing element, then fluid flow to the sensing element is improved, but the sensor die experiences bending or stressing under pressure which causes piezo resistive effects and inaccurate readings
Solution Approach 1:
The backside of the sensor die is segmented into multiple contact regions: a first contact region with conductive pins for electrical connection and a second contact region with a conductive layer for mechanical support. This segmentation allows the electrical and mechanical functions to be separated, enabling the conductive layer to provide structural support while the conductive pins maintain electrical connectivity, thereby preventing piezoresistive effects while ensuring measurement accuracy.
2Reliability
If electrical contacts are located on the backside of the sensor die to enable good fluid flow, then fluid flow is improved, but the device complexity increases due to additional components like conductive pins and conductive layers
Solution Approach 1:
The conductive layer on the backside of the sensor die serves multiple functions: it provides mechanical support to prevent die bending, acts as an electrical conductor for signal transmission, and serves as a mounting surface for the sensor die on the header. By making the conductive layer multi-functional, the patent reduces the need for separate structural support components, thereby simplifying the overall device structure while maintaining measurement accuracy.
3Strength
If the sensor die is mounted with legs attaching near the outer edge, then mechanical support is provided, but the cavity between the backside of the sensor die and the header allows bending and flexing under pressure
Solution Approach 1:
The patent transitions from a conventional edge-mounted leg structure to a backside-contact mounting structure. By moving the mounting interface to the backside of the sensor die and creating direct contact between the conductive layer and the header, the structural support is distributed across the entire backside surface rather than being concentrated at the edges. This dimensional change eliminates the cavity that causes bending while maintaining mechanical support.
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 configuration enhances the mechanical support of the sensor die, reducing piezo resistive effects and improving the accuracy of fluid property measurements by minimizing bending and flexing under pressure, while maintaining electrical coupling through the backside of the sensor die.
Implementation Method 1
one or more electrically conductive pins extending from the third surface partially through the sensor die into the one or more electrically conductive doped regions
Implementation Method 2
A sensing element on a first surface of a sensor die can experience piezo resistive effects when the sensor die is bent or stressed
Data Source
Figure 1~2A
Figure 2B~2C
Figure 2D~2E
AI summary
Embodiments described herein provide for a sensing device including a sensor die attached to a header. The header has a first working surface composed of a first one or more electrically conductive pads and a bulk of the header. The sensor die has a second working surface and a third surface reverse of the second working surface. The sensor die includes a sensing element on the second working surface, and the third surface of the sensor die is composed of a second one or more electrically conductive pads and a dielectric layer. The first one or more electrically conductive pads of the header contact the second one or more electrically conductive pads of the sensor die, and the bulk of the header at the first working surface of the header contacts the dielectric layer of the third surface of the sensor die.