Embedded Wafer Level Optical Package Thickness Reduction
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Solution Overview
Problem
Existing optical packages for semiconductor sensors and LEDs are limited by thickness, footprint size, and cost, with a high component count due to the inclusion of a substrate, cap layer, and glass layer.
Innovation Solution
The method involves forming an embedded wafer level optical package by attaching a sensor die and LED on adhesive tape, encapsulating with a transparent mold compound, removing the carrier, grinding the encapsulation layer, forming vias, filling with conductive material, metalizing, and applying dielectric coatings to reduce thickness and component count, while using a dam made of mold compound or silicon for attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a substrate, cap layer, and glass layer are used in the optical package, then the package provides structural support and protection, but the package thickness and footprint size increase
Solution Approach 1:
The patent merges the functions of the substrate, cap layer, and glass layer into a single integrated eWLOP structure. The carrier wafer serves as the base substrate, while the transparent mold compound encapsulates both the optical components and provides the cap layer functionality. The glass layer is eliminated as its protective function is absorbed by the encapsulation structure, thereby reducing overall package thickness while maintaining structural support.
Solution Approach 2:
The patent extracts and removes the separate glass layer from the traditional optical package structure. By eliminating this redundant protective layer and integrating its function into the mold compound encapsulation, the package thickness is reduced while the essential protection and support functions are preserved through the consolidated eWLOP architecture.
2Reliability
If a substrate, cap layer, and glass layer are included in the optical package, then the package provides comprehensive protection, but the component count and manufacturing cost increase
Solution Approach 1:
The patent combines multiple protective functions into fewer integrated components. The carrier wafer provides mechanical support, while the transparent mold compound simultaneously provides encapsulation, protection, and optical transmission. This consolidation reduces the component count from three separate layers (substrate, cap layer, glass layer) to an integrated eWLOP structure, simplifying manufacturing and reducing costs while maintaining comprehensive protection.
Solution Approach 2:
The transparent mold compound in the eWLOP structure serves multiple functions simultaneously: it provides mechanical protection, structural support, optical transmission, and encapsulation of the optical components. This multi-functional material replaces what would traditionally require multiple separate components, thereby reducing device complexity and component count while maintaining reliable protection.
3Strength
If traditional packaging layers are used, then the package provides structural integrity, but the footprint size and manufacturing cost increase
Solution Approach 1:
The patent merges the structural functions of the substrate and cap layer into the carrier wafer and encapsulation structure, eliminating the need for additional lateral support structures. This consolidation allows the package to achieve the required structural integrity within a smaller footprint area, as the integrated eWLOP structure efficiently distributes mechanical loads without requiring extended package dimensions.
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
This approach results in a thinner, smaller package with reduced costs, as the substrate, cap layer, and glass layer are removed, and the package can be used for applications like proximity sensors in mobile phones.
Implementation Method 1
Encapsulation comprises encapsulation using a transparent mold compound
Implementation Method 2
The vias are formed using laser drilling or laser ablation
Implementation Method 3
The vias are formed using laser drilling or laser ablation
Implementation Method 4
Metalizing the top surface of the encapsulation layer comprises metalizing with copper lines using sputtering, patterning and plating
Implementation Method 5
Patterning the dielectric coating of the bottom surface of the encapsulation layer comprises using a lithography process
Implementation Method 6
Plating the patterned dielectric coating of the bottom surface of the encapsulation layer comprises using UBM (Under Bump Metalization) plating
Data Source
AI summary
A method of forming an embedded wafer level optical package includes attaching a sensor die, PCB bars and an LED on adhesive tape laminated on a carrier, attaching a dam between two light sensitive sensors of the sensor die, encapsulating the sensor die, the PCB bars, the LED, and the dam in an encapsulation layer, debonding the carrier, grinding a top surface of the encapsulation layer, forming vias through the encapsulation layer to the sensor die and the LED, filling the vias with conductive material, metalizing the top surface of the encapsulation layer, dielectric coating of the top surface of the encapsulation layer, dielectric coating of a bottom surface of the encapsulation layer, patterning the dielectric coating of the bottom surface of the encapsulation layer, and plating the patterned dielectric coating of the bottom surface of the encapsulation layer.