Fan-out Sensor Package Optical Member Spacing
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Solution Overview
Problem
The manufacturing process for optical fingerprint sensors in portable devices is complex and prone to damage, leading to decreased photosensitivity due to foreign material penetration and increased stress on optical members during thermal impacts.
Innovation Solution
A fan-out sensor package design that includes a substrate with exposed wiring layers, an image sensor with a sensing region, an optical member spaced apart from the substrate's through-hole walls, and an encapsulant to reduce stress and improve light path efficiency, featuring a dam member and electrical connection structures for enhanced reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an optical member is bonded to an upper portion of an image sensor using an electronic component embedded substrate, then the optical sensor can be implemented, but the manufacturing process becomes complicated and foreign materials may penetrate causing damage to the optical member
Solution Approach 1:
The patent extracts the optical member from the traditional embedded substrate structure and positions it directly on the image sensor surface. This eliminates the complex multi-layer substrate structure and reduces the number of manufacturing steps while preventing foreign material penetration that occurs in bonded structures.
Solution Approach 2:
The patent segments the optical sensor structure into distinct functional layers: the image sensor substrate, the optical member positioned on the sensing surface, and the encapsulant for protection. This segmentation allows for simplified manufacturing while maintaining functional integrity and reducing stress concentration points.
2Volume of moving object
If the optical member is closely positioned to the through-hole walls, then the structure is compact, but stress on the optical member increases during thermal impact
Solution Approach 1:
The patent introduces an intermediary encapsulant material between the optical member and the through-hole walls. This encapsulant acts as a stress-absorbing mediator during thermal expansion and contraction, protecting the optical member from direct mechanical stress while maintaining a compact overall package structure.
Solution Approach 2:
The encapsulant material is applied beforehand to fill the space between the optical member and the substrate, creating a cushioning effect that absorbs thermal stress before it can damage the optical member. This preventive measure ensures reliability under thermal cycling conditions.
3Length of moving object
If the light path to the image sensor is shortened, then the device is more compact, but the sensing area and light detection efficiency are reduced
Solution Approach 1:
The patent positions the optical member on the upper surface of the image sensor rather than embedding it vertically within the substrate. This dimensional reconfiguration allows light to incident horizontally onto the sensing region, maximizing the effective sensing area while maintaining a compact overall device thickness through optimized layer arrangement.
Data Source
AI summary
A fan-out sensor package includes: a substrate in which a through-hole is formed and portions of a wiring layer are exposed from an insulating layer; an image sensor having an active surface having a sensing region disposed below the through-hole of the substrate and connection pads disposed in the vicinity of the sensing region; an optical member disposed on the active surface of the image sensor; a dam member disposed in the vicinity of the sensing region; and an encapsulant encapsulating the substrate and the image sensor, wherein the third wiring layer and the connection pads are electrically connected to each other by connection members.