RDL Edge Encapsulation for Semiconductor Reliability
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Solution Overview
Problem
Existing semiconductor devices face issues with interfacial delamination, crack-induced mechanical stress, and moisture impact due to exposed edges of the redistribution layer (RDL) during assembly and use, as well as thermo-mechanical stress from coefficient of thermal expansion (CTE) differences between packaging and printed circuit boards.
Innovation Solution
Encasing the edges of the RDL within an encapsulant, such as an organic material layer or epoxy mold compound, to protect the RDL from adverse conditions and minimize thermo-mechanical stress by filling the space between interconnect structures, thereby enhancing mechanical strength and reducing failure risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the RDL edges are left exposed during assembly and use, then the device structure remains simple, but interfacial delamination, cracking, and moisture impact occur leading to reduced reliability
Solution Approach 1:
The patent applies preliminary action by forming the encapsulant layer over the RDL edges before final device assembly and testing. This proactive encapsulation prevents delamination and cracking from occurring in the first place, rather than addressing these issues after they manifest during device operation
Solution Approach 2:
The patent uses a thin film encapsulant layer to cover and protect the RDL edges. This thin film provides mechanical protection against delamination and cracking while maintaining device compactness and not significantly increasing overall device complexity
2Reliability
If the RDL edges are exposed to adverse conditions, then the manufacturing process remains simple, but moisture impact and mechanical stress lead to increased failure rates
Solution Approach 1:
The encapsulant layer serves as an intermediary between the RDL edges and adverse environmental conditions (moisture, mechanical stress). This intermediate protective layer blocks harmful factors from directly contacting the RDL, thereby preventing delamination and cracking without complicating the manufacturing process
3Reliability
If space between interconnect structures is left empty, then device fabrication is simpler, but thermo-mechanical stress from CTE differences reduces board-level reliability
Solution Approach 1:
The encapsulant layer performs multiple functions simultaneously: it protects RDL edges from delamination and cracking, blocks moisture ingress, and fills spaces between interconnect structures to mitigate thermo-mechanical stress from CTE differences. This multi-functionality achieves multiple reliability improvements through a single manufacturing step
Solution Approach 2:
The patent addresses thermo-mechanical stress by changing the physical state and distribution of the encapsulant material to fill voids between interconnect structures. This material placement modifies the thermal and mechanical parameter distribution, reducing stress concentration points caused by CTE mismatches during temperature cycling
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 encapsulation of the RDL edges prevents interfacial delamination, cracking, and thermo-mechanical stress, improving the reliability and durability of semiconductor devices by providing protection against moisture and mechanical stress, and enhancing board-level reliability statistics.
Implementation Method 1
encasing the edges of the RDL within an encapsulant
Implementation Method 2
thermo-mechanical stress from coefficient of thermal expansion (CTE) differences between packaging and printed circuit boards
Data Source
AI summary
A semiconductor device having a semiconductor die, a redistribution layer (RDL), and an encapsulant. The RDL layer can be formed on a first surface of the semiconductor die. The encapsulant can enclose a second surface and side surfaces of the semiconductor die. The encapsulant can enclose side portions of the RDL.