Sensor Chip Encapsulation Using Protective Layer and Temporary Carrier
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Solution Overview
Problem
Conventional sensor chip packaging methods increase fabrication costs and package size due to the need for a transparent plate that does not cover bonding pads, compromising the neatness and efficiency of the packaging process.
Innovation Solution
A method involving a protective layer on the sensor chip's active surface, which covers the sensor region and allows attachment to a temporary carrier, enabling local encapsulation with an encapsulant that covers the back and side surfaces, followed by removal of the temporary carrier and protective layer to expose the sensor region for electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a transparent plate is attached to the active surface of the sensor chip to cover the sensor region, then the sensor region is protected from pollution, but the package size increases and fabrication cost increases
Solution Approach 1:
The patent divides the protective coverage into segments: the sensor region is covered during packaging, while the bonding pads remain exposed. This is achieved by forming the encapsulant to specifically cover the back surface and side surfaces of the sensor chip without extending over the bonding pads on the active surface, eliminating the need for a transparent plate that would obstruct electrical connections.
Solution Approach 2:
The patent extracts the transparent plate from the package structure by implementing local encapsulation that provides protection without requiring a covering plate over the entire active surface. The encapsulant is selectively applied only where protection is needed (back and side surfaces), leaving the bonding pads accessible for wire bonding.
2Object-affected harmful factors
If a transparent plate is attached to cover the sensor region, then the sensor region is protected from pollution, but fabrication cost increases
Solution Approach 1:
The patent removes the transparent plate component entirely by using local encapsulation technology. The encapsulant material is applied directly to the sensor chip's back and side surfaces during the packaging process, providing the same protective function against pollution without requiring an additional transparent plate layer that would increase fabrication complexity and cost.
Solution Approach 2:
The patent merges the protective function with the encapsulation process itself. Instead of adding a separate transparent plate layer, the encapsulant is formulated and applied to simultaneously provide mechanical protection, environmental sealing, and sensor region protection in a single integrated process, reducing the total number of manufacturing steps.
3Object-affected harmful factors
If the package structure includes a transparent plate over the sensor region, then the sensor region is protected, but the package profile becomes less neat and larger
Solution Approach 1:
The patent applies different protective qualities to different regions of the sensor chip. The back surface and side surfaces receive full encapsulation coverage for maximum protection and neat appearance, while the active surface with bonding pads maintains an open, accessible profile for electrical connections. This localized differentiation achieves both protection and aesthetic neatness without the bulk of a full transparent plate.
Data Source
AI summary
A method for encapsulating sensor chips is disclosed. A protective layer is formed on an active surface of a sensor chip, and at least covers a sensor region in the active surface. The active surface of the sensor chip faces to a temporary carrier, so that the protective layer is attached to the temporary carrier. An encapsulant is formed on the temporary carrier to cover a back surface and side surfaces of the sensor chip. A plurality of electrically connecting components are formed in the encapsulant to electrically connect a plurality of bonding pads of the sensor chip, and then the protective layer is removed to expose the sensor region. The coverage of the protective layer is used to avoid pollution on the sensor region during encapsulating, thereby, especially in a wafer level packaging, making the package profile neat, tidy and smaller in size, and promoting production efficiency.