Sidewall Protected Image Sensor Package with Hermetic Sealing
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Solution Overview
Problem
Existing semiconductor image sensor packaging technologies face challenges in integrating additional circuitry, such as image signal processors, within the same IC package for improved imaging performance, particularly in applications like automotive ADAS and autonomous driving, while ensuring hermetic sealing and optical integrity.
Innovation Solution
A chip-scale package assembly that includes an image sensor die and a glass cover with a molding material layer on the sidewalls, hermetically sealing the assembly and incorporating redistribution layers and solder bumps for electrical connections, allowing for the integration of additional circuitry and protection from environmental factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a glass cover is placed over the image sensor die with additional circuitry underneath, then imaging performance is improved through integrated signal processing, but hermetic sealing becomes difficult to achieve
Solution Approach 1:
The patent transitions from planar sealing approaches to three-dimensional sidewall sealing. Molding material is applied to the sidewalls of the package cavity, creating a vertical seal barrier that effectively seals the package while accommodating the multi-layer structure of image sensor die, additional circuitry, and glass cover.
Solution Approach 2:
The patent employs composite sealing structures combining molding material applied to sidewalls with adhesive materials for glass cover attachment. This composite approach integrates different material properties to achieve both hermetic sealing and structural integrity in the multi-layer package configuration.
2Adaptability or versatility
If additional circuitry is integrated underneath the image sensor die, then imaging performance improves through on-chip signal processing, but package complexity increases
Solution Approach 1:
The patent merges the image sensor die with additional circuitry (such as ISP or ASIC die) into a single integrated package structure. The molding material unifies these separate components by filling and sealing the cavity around them, creating a consolidated package that reduces overall system complexity despite the increased functional integration.
Solution Approach 2:
The molding material serves multiple functions simultaneously: it provides hermetic sealing, mechanical support for the multi-layer structure, electrical insulation, and structural unity for the integrated circuitry. This multi-functionality simplifies the overall package design despite the complex internal architecture.
3Strength
If the glass cover width is larger than the image sensor die width, then optical protection and structural integrity are enhanced, but the amount of adhesive material and manufacturing complexity increase
Solution Approach 1:
The patent applies adhesive material in a localized bead configuration at the periphery where the glass cover contacts the package structure. This localized application provides sufficient structural support and sealing at the critical interface without requiring extensive adhesive coverage, thereby reducing manufacturing complexity while maintaining structural integrity.
4Reliability
If sidewall sealing with molding material is used instead of traditional bottom sealing, then hermetic sealing is achieved while accommodating multi-layer structures, but the manufacturing process complexity increases
Solution Approach 1:
The molding material is applied to the sidewalls in advance, creating a pre-formed sealing structure before final package assembly. This preliminary sealing action accommodates the multi-layer structure and ensures hermetic sealing is established before subsequent manufacturing steps, simplifying the overall process despite the additional sidewall application step.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables the creation of hermetically sealed, surface-mountable image sensor packages that integrate additional circuitry, enhance optical performance, and protect the image sensor from physical and environmental damage, addressing the need for improved imaging capabilities in advanced automotive systems.
Implementation Method 1
The glass cover is attached to the image sensor die by a bead of adhesive material placed on an edge of the image sensor die
Implementation Method 2
The layer of molding material hermetically seals the assembly of the image sensor die and the glass cover
Data Source
AI summary
A method includes disposing a sheet of glass on a front side of a semiconductor substrate that includes at least one image sensor die, attaching the sheet of glass to the at least one image sensor die by a bead of adhesive material disposed on an edge of the at least one image sensor die, and sawing the semiconductor substrate from a back side to form a trench along a side of the at least one image sensor die. The trench extends through a thickness of the semiconductor substrate and through a part of a thickness of the sheet of glass. The method further includes filling the trench with a molding material to form a layer of molding material on a sidewall of the at least one image sensor die, and singulating the semiconductor substrate to isolate an individual image sensor package enclosing the at least one image sensor die.