RDL Trace Layout Across Component Gaps for Stress Mitigation

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Solution Overview

Problem

Current microelectronic packaging technologies face challenges in maintaining mechanical integrity of redistribution layers (RDLs) due to high stress across the gap between adjacent components, primarily caused by bending and thermal expansion differences, which can lead to RDL crack propagation and package failure.

Innovation Solution

The implementation of various RDL layouts, including wider and angled wiring traces, provides mechanical integrity by increasing metal density and strain mitigation in high stress regions. These layouts involve wider traces perpendicular to the gap and angled traces across the gap, with optional inclusion of RDL chiplets to displace wiring layers and shift terminal arrangements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If standard RDL wiring trace layouts are used, then manufacturing is simple, but mechanical integrity deteriorates due to high stress and crack propagation

Engineering Contradiction:

Improvemechanical integrity of RDLVSAvoidRDL layout complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent applies local quality by making wiring traces wider specifically in high-stress regions (such as across component gaps) while maintaining standard dimensions in low-stress areas. This localized modification strengthens the RDL where needed without unnecessarily complicating the entire layout, directly resolving the contradiction between mechanical integrity and device complexity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements preliminary action by designing wider wiring traces in advance in regions predicted to experience high stress, such as across component gaps. This preventive design approach strengthens the RDL before stress occurs, preventing crack propagation while avoiding the need for complex reinforcement structures.

Inventive Principle:

Principle #10Preliminary action

2Stress or pressure

If wiring traces are made wider to increase metal density, then stress resistance improves, but manufacturing precision requirements increase

Engineering Contradiction:

Improvestress in high stress regionVSAvoidwiring trace dimension control

Core Design Contradiction:

Stress or pressureVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

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 proposed RDL layouts effectively reduce stress and prevent crack propagation, enhancing the mechanical integrity and reliability of microelectronic packages without significantly altering metal density, thus preventing package failure.

Implementation Method 1

the first wiring traces are wider than the second wiring traces. In this manner, the wider wiring traces can provide mechanical integrity to the RDL in a high stress region between the first and second component

Methodology Applied

Scientific EffectStress mitigation through increased metal density:

Implementation Method 2

the RDL includes a first group of wiring traces extending at an oblique angle across an RDL gap width between the first component and the second component. In this manner, the angled wiring traces may be slightly lengthened, providing an increased metal density and mechanical integrity to the RDL in a high stress region

Methodology Applied

Scientific EffectStress mitigation through increased metal density:

Data Source

PatentUS20260018527A1Microelectronic Package RDL Patterns to Reduce Stress in RDLs Across Components

Publication Date: 2026.01.15 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.