Extended RDL Shielding for WLCSP Edge Crack Resistance
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Solution Overview
Problem
Wafer level packaging architectures face challenges with sensitive mechanical assembly processes and micro cracks in exposed active silicon regions, leading to assembly yield loss and reliability issues due to thermo-mechanical stresses and humidity, which existing solutions have not adequately addressed.
Innovation Solution
The implementation of extended redistribution layer (RDL) structures that provide seamless protection over exposed active die regions, including conductive pillars and shields, to prevent micro crack propagation and enhance mechanical robustness against assembly and environmental stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If wafer level packaging architectures are used to enable miniaturization, then form factor is reduced and integration is increased, but the packages have unprotected exposed surfaces and regions that are sensitive to mechanical assembly processes and environmental stresses
Solution Approach 1:
The patent applies preliminary action by forming the extended RDL structure and dielectric layers over the active die regions before the singulation process. This pre-protection ensures that the exposed surfaces and regions are covered with protective dielectric material and conductive structures prior to dicing, preventing mechanical damage and micro crack generation during the singulation process and subsequent assembly operations.
Solution Approach 2:
The patent employs composite materials by combining multiple dielectric layers with conductive RDL structures to create a multi-layer protective system. The extended RDL portions are embedded within dielectric layers, forming a composite structure that provides both mechanical protection and electrical functionality while protecting the exposed active die regions from environmental stresses and mechanical damage.
2Reliability
If crack stop structures or special singulation processes are implemented to reduce micro cracks, then micro crack propagation is reduced, but manufacturing complexity and process steps increase
Solution Approach 1:
The patent merges the crack stop function with the existing RDL structure by extending the conductive layer and embedding it within dielectric layers. Instead of adding separate crack stop structures, the extended RDL portions serve dual purposes: providing electrical interconnect functionality and acting as crack stop structures that prevent micro crack propagation during singulation and assembly, thereby reducing manufacturing complexity.
Solution Approach 2:
The extended RDL structure performs multiple functions simultaneously: it provides electrical interconnect pathways, serves as a crack stop structure to prevent micro crack propagation, and offers mechanical protection to the active die regions. This multi-functionality eliminates the need for separate dedicated crack stop structures, simplifying the manufacturing process while maintaining reliability.
3Reliability
If underfill and mold materials are used to cover critical active areas, then protection against environmental stresses is improved, but assembly time increases and manufacturing costs increase
Solution Approach 1:
The patent applies preliminary action by forming the extended RDL structures and dielectric layers over the active die regions before singulation and assembly. This pre-protection eliminates the need for subsequent underfill and mold material application steps, as the protective dielectric structure is already in place prior to device assembly, significantly reducing assembly time and manufacturing costs.
Solution Approach 2:
The patent extracts the protective function from the traditional post-assembly underfill and mold material processes and integrates it into the pre-assembly RDL structure. By embedding the conductive RDL portions within dielectric layers before singulation, the protection function is built-in from the beginning, eliminating the need for additional protective materials and complex assembly steps.
4Reliability
If extended RDL structures are implemented to protect exposed active die regions, then assembly yield and reliability are improved, but device complexity increases
Solution Approach 1:
The extended RDL structure performs multiple functions simultaneously: it provides electrical interconnect pathways, serves as a crack stop structure to prevent micro crack propagation, and offers mechanical protection to the active die regions. This multi-functionality means that while the structure is extended, it does not add dedicated separate protective components, thereby limiting the increase in device complexity while achieving multiple protective benefits.
Data Source
AI summary
Embodiments disclosed herein include electronic packages. In an embodiment, an electronic package comprises a redistribution layer (RDL) having a conductive layer in a first dielectric layer, and a second dielectric layer over the conductive and first dielectric layers. The RDL comprises an extended portion having a first thickness that vertically extends from a bottom surface of the first dielectric layer to a topmost surface of the second dielectric layer. The electronic package comprises a die on the RDL, where the die has sidewall surfaces, a top surface, and a bottom surface that is opposite from the top surface, and an active region on the bottom surface of the die. The first thickness is greater than a second thickness of the RDL that vertically extends from the bottom surface of the first dielectric layer to the bottom surface of the die. The extended portion is over and around the sidewall surfaces.