Semiconductor Package Window for Fingerprint Sensing
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Solution Overview
Problem
The challenge in semiconductor packaging is to miniaturize the package structure while maintaining or improving sensing capabilities, particularly for fingerprint recognition systems, which requires reducing the thickness of the package structure to enhance detection efficiency.
Innovation Solution
A manufacturing method that involves forming conductive connectors on a circuit layer, encapsulating a chip with an encapsulant, and creating a redistribution layer with a window corresponding to the sensing area, which reduces the overall thickness and improves sensing capabilities by minimizing the distance between the sensing area and the package surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the package structure is miniaturized to reduce thickness, then the volume and weight of the package are reduced, but the sensing capability deteriorates due to increased distance from the sensing area to the surface
Solution Approach 1:
The patent applies dimensionality change by creating a window opening in the encapsulant directly above the sensing area, transitioning from a planar encapsulation to a three-dimensional structure with a vertical access path. This allows the sensing area to be positioned closer to the top surface of the package while maintaining overall package miniaturization, thereby resolving the contradiction between reduced volume and preserved sensing capability.
Solution Approach 2:
The patent extracts the encapsulant material from the region directly above the sensing area by forming a window opening. This removal of material creates a direct optical path from the top surface to the sensing area, eliminating the need for light to penetrate through the entire thickness of the encapsulant, thus maintaining sensing capability while enabling package miniaturization.
2Measurement precision
If the encapsulant thickness is reduced to improve sensing capability, then the distance from the sensing area to the surface is reduced, but the protective function of the encapsulant deteriorates
Solution Approach 1:
The patent applies local quality by creating a window opening specifically at the region corresponding to the sensing area, while maintaining the full thickness encapsulant in all other regions. This localized modification provides optical access where needed without compromising the overall protective function of the encapsulant, thus resolving the contradiction between improved sensing capability and maintained protective strength.
3Measurement precision
If a window is added to the encapsulant to improve sensing capability, then the sensing area is exposed, but the manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by forming the window opening in the encapsulant during the encapsulation process itself, before final packaging is completed. The window is created as part of the encapsulant formation step, allowing subsequent assembly operations to proceed without additional complex processing, thus minimizing manufacturing complexity while achieving the sensing exposure.
4Volume of moving object
If the redistribution layer is positioned closer to the sensing area to reduce package thickness, then the overall package size is reduced, but the electrical connection complexity increases
Solution Approach 1:
The patent applies dimensionality change by routing electrical connections through the window opening in the vertical dimension, rather than requiring lateral routing through the encapsulant. This three-dimensional connection path allows the redistribution layer to be positioned closer to the sensing area, reducing package volume while simplifying the electrical connection geometry compared to planar routing approaches.
Data Source
AI summary
A manufacturing method of a package structure includes at least the following steps. A plurality of conductive connectors are formed on a circuit layer. The circuit layer includes a central region and a peripheral region electrically connected to the central region. A chip is disposed on the central region of the circuit layer. The chip includes an active surface at a distance from the circuit layer and a sensing area on the active surface. An encapsulant is formed on the circuit layer to encapsulate the chip and the conductive connectors. A redistribution layer is formed on the encapsulant to electrically connect the chip and the conductive connectors. The redistribution layer partially covers the chip and includes a window corresponding to the sensing area of the chip. A package structure is also provided.