RDL Trace Patterning Across Components to Mitigate Package Stress

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Solution Overview

Problem

Existing microelectronic packages face high stress and potential failure due to bending and thermal expansion differences across redistribution layers (RDLs) between adjacent components, particularly in thinner designs, leading to crack propagation.

Innovation Solution

The RDLs are redesigned with specific trace patterns, including wider and angled wiring traces, and optionally incorporating RDL chiplets, to enhance mechanical integrity and mitigate stress across the gap between components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If standard RDL trace patterns are used, then manufacturing is simpler, but stress and crack propagation occur in thinner designs

Engineering Contradiction:

ImproveRDL mechanical integrityVSAvoidRDL trace pattern complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies different trace widths at different locations within the RDL pattern. Specifically, traces spanning the gap between adjacent components are made wider than traces in other regions. This local variation in trace quality provides enhanced mechanical strength precisely where stress is highest, while maintaining simpler patterns in low-stress areas.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent modifies the geometric parameters of the RDL traces, specifically varying the trace width as a parameter. By changing the width parameter of traces in high-stress regions compared to low-stress regions, the design optimizes mechanical integrity without uniformly increasing complexity across the entire RDL structure.

Inventive Principle:

Principle #35Parameter changes

2Length of moving object

If RDL thickness is reduced, then package size decreases, but stress and cracking increase

Engineering Contradiction:

ImproveRDL thicknessVSAvoidRDL stress resistance

Core Design Contradiction:

Length of moving objectVSStrength

Solution Approach 1:

The patent compensates for reduced overall RDL thickness by creating localized regions of enhanced trace width in high-stress areas. This local quality enhancement provides the necessary strength in critical regions even when the overall RDL structure is thinner, allowing package size reduction without proportionally sacrificing strength.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The RDL structure can be viewed as a composite design where traces of different widths are combined within the same layer. The wider traces in high-stress regions act as reinforcement elements, creating a composite structural approach that maintains strength despite reduced overall thickness.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS12456692B2Microelectronic package RDL patterns to reduce stress in RDLs across components

Publication Date: 2025.10.28 APPLE INC

AI summary

Microelectronic packages and methods of fabrication are described. In an embodiment, a redistribution layer spans across multiple components, and includes a region of patterned wiring traces that may mitigate stress in the RDL between the multiple components.