Sensor Cavity IC Sealing With Continuous Wall and Film Cover
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Solution Overview
Problem
Existing cavity integrated circuit (IC) packages face issues with foreign substances entering the sensor cavity during fabrication, compromising the sensor's operation, due to open cavities or incomplete closure, which is exacerbated by current photolithography processes.
Innovation Solution
A substrate with a sensor surrounded by a continuous trench and a plated metal wall, sealed with a lamination film cover to form a closed cavity, ensuring protection from external elements, and using under bump metallization layers for electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a cavity is left open during fabrication, then the sensor can be accessed and positioned, but foreign substances can enter the cavity and compromise sensor operation
Solution Approach 1:
The cavity structure is segmented into multiple components: the cavity body, the cover, and the sealing mechanism. This allows the cavity to be open during fabrication for sensor access, then closed afterward to prevent foreign substance entry, resolving the contradiction between manufacturing accessibility and operational reliability
Solution Approach 2:
The sensor is positioned and secured in the cavity before the cover is attached. This preliminary action ensures the sensor is properly placed while the cavity remains open, and subsequent closing actions prevent contamination without requiring re-opening, thus maintaining both manufacturing ease and reliability
2Reliability
If a cover is added to close the cavity, then foreign substances are prevented from entering, but the fabrication process becomes more complex
Solution Approach 1:
The cover is integrated with the cavity structure through alignment features and sealing mechanisms that combine multiple functions into a single component. This merging reduces the number of separate parts and assembly steps, protecting the cavity while minimizing fabrication complexity
Solution Approach 2:
The cover utilizes thin-film sealing structures that can be deposited or attached in a single process step, providing effective sealing without requiring complex mechanical assemblies. This approach protects the cavity from foreign substances while keeping the fabrication process relatively simple
3Manufacturing precision
If traditional photolithography processes are used, then circuit patterns can be formed, but the cavity closure becomes incomplete and allows substance entry
Solution Approach 1:
An intermediary sealing structure is introduced between the cavity body and the cover, acting as a mediator that ensures complete closure. This sealing intermediary compensates for tolerances and imperfections in traditional photolithography processes, preventing substance entry while maintaining circuit pattern precision
Solution Approach 2:
The sealing structure utilizes composite materials or multi-layer constructions that combine the precision-formable properties needed for circuit patterns with the sealing properties needed for complete cavity closure. This resolves the contradiction between manufacturing precision and sealing reliability
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 prevents foreign substances from entering the sensor cavity, maintaining sensor functionality and reliability by isolating it from fabrication and environmental stresses.
Implementation Method 1
A cover is formed over the continuous wall to close off an open top of the continuous wall to thereby form a cavity inside the continuous wall
Data Source
AI summary
An electronic device is provided and includes a substrate having an active surface and a sensor disposed on an active surface of the substrate, where the sensor is in communication with the active surface of the substrate. The electronic device further includes a continuous wall having an open top disposed on the active surface of the substrate, where the continuous wall surrounds the sensor. A cover is disposed on a top surface of the continuous wall, where the cover closes off the open top of the continuous wall to form a cavity inside the continuous wall to prevent foreign substance from entering the cavity.