3D Image Sensor Stack Packaging for Noise Reduction
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Solution Overview
Problem
Current image sensor packaging structures face challenges in reducing package size, minimizing noise in image signals, and lowering manufacturing costs while ensuring durability and protection from moisture.
Innovation Solution
A stack packaging structure that includes a substrate with semiconductor devices, an image sensor device, inner and outer moldings, and a transparent member, where the semiconductor devices are coupled in a flip-chip configuration with under-fill material and encapsulated within the inner molding, and the bond wires and transparent member are encapsulated within the outer molding, enhancing durability and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If IC devices are assembled on the backend of the PCB with long traces, then connectivity is achieved, but the package size increases and noise increases
Solution Approach 1:
The patent transitions from a planar 2D PCB assembly to a 3D stacked architecture where the image sensor device is vertically positioned above the PCB substrate. This vertical stacking enables direct electrical connection through through-substrate vias, eliminating the need for long surface traces and reducing the horizontal package footprint while maintaining connectivity.
2Reliability
If IC devices are assembled on the backend of the PCB with long traces, then connectivity is achieved, but noise in image signals increases
Solution Approach 1:
By moving the image sensor device to a vertical stack above the PCB, the patent eliminates long horizontal signal traces that act as antennas for electromagnetic interference. The through-substrate via connections provide direct, short signal paths, significantly reducing noise and improving signal integrity.
Solution Approach 2:
The patent introduces intermediate connection structures including through-substrate vias and redistribution layers that act as mediators between the image sensor device and PCB. These intermediaries provide controlled impedance paths and shielding, reducing electromagnetic interference and noise compared to direct long-trace connections.
3Reliability
If the image sensor device is exposed without encapsulation, then manufacturing is simpler, but durability and protection from moisture are reduced
Solution Approach 1:
The patent implements a multi-layer encapsulation system where an inner molding material encapsulates the image sensor device first, creating a hermetic seal. This inner encapsulation is then nested within an outer molding structure that provides additional mechanical protection and environmental sealing, achieving superior moisture protection through nested protective layers.
4Reliability
If a single molding structure is used, then manufacturing is simpler, but noise reduction and durability are insufficient
Solution Approach 1:
The patent employs a nested dual-molding architecture where the inner molding material directly encapsulates the image sensor device, providing the first level of protection and noise isolation. The outer molding structure then encapsulates the inner molding assembly, adding mechanical strength and environmental sealing. This nested configuration achieves enhanced durability and noise reduction that a single molding structure cannot provide.
Solution Approach 2:
The patent assigns different material properties to different molding layers: the inner molding material is selected for optimal adhesion to the image sensor device and noise dampening properties, while the outer molding material provides superior mechanical strength and environmental barrier properties. This local differentiation of material qualities optimizes overall performance.
Data Source
AI summary
According to an aspect, a stack packaging structure includes a substrate, a semiconductor device coupled to a surface of the substrate, an image sensor device coupled to the semiconductor device such that the semiconductor device is disposed between the surface of the substrate and the image sensor device, at least one bond wire connected to the image sensor device and the surface of the substrate, a inner molding disposed between the surface of the substrate and the image sensor device, where the semiconductor device is encapsulated within the inner molding, and an outer molding disposed on the surface of the substrate, where the at least one bond wire is encapsulated within the outer molding.