RDL Substrate With Photosensitive Dielectrics for Warpage Control

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Solution Overview

Problem

Existing package-on-package (POP) IC packages face challenges in achieving high interconnection density without increasing package height, while also minimizing warpage and die delamination due to thermal expansion and material asymmetries.

Innovation Solution

Employing a re-distribution layer (RDL) substrate with photosensitive non-polymer dielectric material layers that have a higher modulus and lower coefficient of thermal expansion (CTE) to enhance package rigidity, allowing for thinner metallization layers that support increased interconnection density and reduce warpage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a thinner package substrate is used to conserve area, then the height of the package is reduced, but the package becomes more susceptible to warpage causing die delamination and interconnection breakage

Engineering Contradiction:

Improvepackage heightVSAvoidwarpage resistance

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent changes the material parameters of the dielectric layers by using photosensitive non-polymer materials with specifically controlled modulus and CTE values. This allows optimization of the substrate's mechanical properties to resist warpage while maintaining thin profile.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structures with multiple dielectric layers having different material compositions and properties. The combination of photosensitive non-polymer materials creates a composite substrate that achieves both thinness and warpage resistance through synergistic material properties.

Inventive Principle:

Principle #40Composite materials

2Volume of moving object

If RDL metallization layers are formed from thin dielectric material layers, then the substrate height is minimized to conserve area, but the package becomes more susceptible to warpage

Engineering Contradiction:

Improvesubstrate heightVSAvoidrigidity

Core Design Contradiction:

Volume of moving objectVSStrength

Solution Approach 1:

The patent modifies the physical parameters of the dielectric material by selecting photosensitive non-polymer materials with high modulus values. This enables the thin layers to maintain sufficient rigidity and resistance to warpage despite reduced thickness.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies different material properties to different layers of the substrate structure. Each dielectric layer is engineered with specific material characteristics optimized for its position and function, creating local quality variations that collectively enhance overall rigidity while maintaining thin profile.

Inventive Principle:

Principle #3Local quality

3Strength

If photosensitive non-polymer dielectric material layers with higher modulus and lower CTE are used, then package rigidity is increased and warpage is reduced, but the manufacturing process complexity increases

Engineering Contradiction:

Improvepackage rigidityVSAvoidmaterial selection complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent replaces traditional mechanical reinforcement methods with material property optimization. Instead of adding structural complexity or thicker layers to increase rigidity, the solution substitutes photosensitive non-polymer materials with inherently superior mechanical properties, simplifying the overall design approach.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 use of photosensitive non-polymer dielectric material layers in RDL substrates reduces warpage and die delamination, enabling higher interconnection density without increasing package height, and simplifies the process of controlling warpage-related complexities.

Implementation Method 1

The photosensitive dielectric non-polymer material is selected to have a higher material modulus for increased stiffness and/or a lower coefficient of thermal expansion (CTE)

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentUS12463127B2Integrated circuit (IC) package employing a re-distribution layer (RDL) substrate(s) with photosensitive dielectric layer(s) for increased package rigidity, and related fabrication methods

Publication Date: 2025.11.04 QUALCOMM INC

AI summary

Integrated circuit (IC) packages employing a re-distribution layer (RDL) substrate(s) with photosensitive non-polymer dielectric material layers for increased package rigidity, and related fabrication methods. To reduce or minimize warpage of an IC package employing a RDL substrate, the RDLs of the RDL substrate are photosensitive non-polymer dielectric material layers. The photosensitive non-polymer dielectric material layers can exhibit increased rigidity as a result of being hardened when exposed to light and cured during fabrication of the RDL substrate. The photosensitive non-polymer dielectric material layers can also exhibit increased rigidity as a result of being an inorganic polymer (e.g., SiOx, SiN material) that has a higher material modulus for increased stiffness and/or a lower coefficient of thermal expansion (CTE) for reduced thermal contraction and expansion, as opposed to for example, an organic polymer material (e.g., Polyimide) which has less stiffness and a higher CTE.