Sensor Chip Back-Side Sensing Element for Contamination Protection
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Solution Overview
Problem
Sensor chips face exposure issues during handling and mounting, as the sensing element is typically positioned on the front side, making it inaccessible to the medium being measured and vulnerable to contamination during the soldering process.
Innovation Solution
A sensor chip design with a substrate having an opening from the back side to the front side, allowing the sensing element to be placed within the substrate, protected by a stack of dielectric and conducting layers, enabling flip chip mounting without direct exposure to the circuit board, and incorporating a membrane for medium access and protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the sensing element is positioned on the front side of the substrate, then it can be easily accessed during manufacturing, but it becomes exposed to contamination and inaccessible to the medium being measured during handling and mounting
Solution Approach 1:
The sensing element is inverted from the conventional front-side position to the back-side position of the substrate. This inversion allows the sensing element to be protected from contamination during handling and mounting while still enabling medium access through the opening, resolving the contradiction between ease of manufacture and protection from contamination
Solution Approach 2:
The sensing element is nested within the substrate by positioning it on the back side and providing medium access through an opening. This nesting approach protects the sensing element from external contamination while maintaining its functionality, addressing the contradiction between accessibility and protection
2Ease of operation
If the sensing element is positioned on the front side facing the circuit board, then flip chip mounting is enabled, but the medium cannot sufficiently access the sensing element
Solution Approach 1:
Instead of facing the sensing element toward the circuit board, the invention inverts the arrangement by positioning the sensing element on the back side of the substrate. This allows flip chip mounting to proceed as normal while the opening provides sufficient medium access to the sensing element, resolving the contradiction between mounting capability and medium access
3Ease of manufacture
If the sensing element is exposed during handling and soldering, then manufacturing processes are simplified, but the sensing element becomes vulnerable to contamination
Solution Approach 1:
The sensing element is preliminarily positioned on the back side of the substrate before handling and mounting operations. This preliminary positioning action protects the sensing element from contamination during subsequent manufacturing processes while maintaining process simplicity, as the back-side position is naturally protected during flip chip mounting and soldering
Solution Approach 2:
The sensing element is nested within the substrate structure on the back side, which provides inherent protection during handling and soldering processes. This nesting approach maintains manufacturing simplicity while reducing contamination vulnerability, as the sensing element is not directly exposed to external environments during these processes
Data Source
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AI summary
A sensor chip comprises a substrate (1) with a front side (11) and a back side (12), and an opening (13) in the substrate (1) reaching through from its back side (12) to its front side (11). A stack (2) of dielectric and conducting layers is arranged on the front side (11) of the substrate (1), a portion of which stack (2) spans the opening (13) of the substrate (1). Contact pads (32) are arranged at the front side (11) of the substrate (1) for electrically contacting the sensor chip. A sensing element (4) is arranged on the portion of the stack (2) spanning the opening (13) on a side of the portion facing the opening (13).