Wafer-Level Sensing Device Packaging Process
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Solution Overview
Problem
Conventional sensing device formation processes are complex and have low yield, with the sensing chip being recessed and vulnerable to damage, leading to inconvenience and potential device failure.
Innovation Solution
A method involving a first substrate with a sensing region, a temporary cover plate, and a redistribution layer, where the temporary cover plate is removed after forming the redistribution layer, and the substrate is bonded between a second substrate and a cover plate with an encapsulating layer to surround the first substrate, simplifying the process and enhancing protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional chip packaging process is used, then sensing device can be formed, but the process is complicated and has low yield
Solution Approach 1:
The patent merges the sensing chip fabrication and packaging processes into a single integrated wafer-level process. Multiple sensing chips are fabricated and packaged simultaneously on a common substrate, eliminating the need for separate packaging steps for each chip. This integration simplifies the overall process and significantly improves yield by reducing the number of discrete manufacturing steps.
Solution Approach 2:
The common substrate serves multiple functions: it acts as the base for fabricating multiple sensing chips, provides structural support during processing, and serves as the final packaging structure. This multi-functional design eliminates the need for separate packaging components and reduces process complexity.
2Ease of operation
If sensing chip is recessed from the shell, then packaging is achieved, but it is inconvenient to use
Solution Approach 1:
Instead of recessing the sensing chip into the packaging shell as in conventional designs, the patent inverts the approach by making the sensing surface coplanar with or protruding from the packaging structure. The sensing chips are mounted on the upper surface of the common substrate, creating a flat sensing surface that is easily accessible and convenient for user interaction.
3Reliability
If sensing chip or chip package is damaged, then the whole device will not work
Solution Approach 1:
The patent segments the sensing system into multiple independent sensing chips mounted on a common substrate. Each sensing chip operates independently, so if one chip is damaged or fails, the other chips continue to function. This segmentation provides redundancy and improves overall system reliability, ensuring that the device can still operate with reduced functionality rather than complete failure.
Data Source
AI summary
A method for forming a sensing device includes providing a first substrate. The first substrate has a first surface and a second surface opposite thereto. A sensing region is adjacent to the first surface. A temporary cover plate is provided on the second surface to cover the sensing region. The method also includes forming a redistribution layer on the second surface and electrically connected to the sensing region. The method further includes removing the temporary cover plate after the formation of the redistribution layer. The first substrate is bonded to a second substrate and a cover plate after the removal of the temporary cover plate so that the first substrate is positioned between the second substrate and the cover plate. In addition, the method includes filling an encapsulating layer between the second substrate and the cover plate to surround the first substrate.