Partial Redistribution Layer Protection via Solder Reflow

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Solution Overview

Problem

Wafer-level packaging faces increased cost and complexity due to the need for additional processing steps and materials to protect redistribution layers from corrosion, especially with the demand for smaller package sizes and added circuit elements.

Innovation Solution

The use of solder formation and reflow techniques to create a partial redistribution layer protection layer, where solder material drifts and collapses over the metal surface, eliminating the need for dedicated protection processes like dielectric formation or noble metal application, thereby reducing costs and complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional protection methods (dielectric formation, noble metal application) are used to protect redistribution layers, then corrosion protection is improved, but manufacturing cost and process complexity increase

Engineering Contradiction:

Improvecorrosion protection of redistribution layerVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the redistribution layer and protection layer into a single integrated structure, where the protection layer is formed simultaneously with the redistribution layer during the same manufacturing process. This eliminates the need for separate protection processes and reduces overall manufacturing complexity while maintaining corrosion protection.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The protection layer is designed to serve multiple functions: it provides corrosion protection for the redistribution layer, acts as an electrical insulator, and serves as a structural support. This multi-functionality reduces the need for additional dedicated protection components and simplifies the overall device architecture.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If additional protection processing steps are added to protect redistribution layers, then corrosion protection is improved, but manufacturing cost increases

Engineering Contradiction:

Improvecorrosion protection of redistribution layerVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The manufacturing process combines the formation of the redistribution layer and protection layer into a single integrated process step. By forming both layers simultaneously using the same deposition and patterning techniques, the patent eliminates additional processing steps and associated costs while ensuring adequate corrosion protection.

Inventive Principle:

Principle #5Merging (Combining)

3Volume of moving object

If package size is reduced to meet market demands, then product competitiveness is improved, but protection of redistribution layers becomes more difficult

Engineering Contradiction:

Improvepackage sizeVSAvoidprotection of redistribution layer

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent employs a thin-film protection layer that provides effective corrosion protection despite the reduced package size. The thin-film structure maintains adequate protective functionality while occupying minimal space, allowing the overall package to remain compact without compromising redistribution layer protection.

Inventive Principle:

Principle #30Flexible shells and thin films

4Adaptability or versatility

If circuit elements are added to increase functionality, then product capability is improved, but manufacturing complexity and cost increase

Engineering Contradiction:

Improvecircuit element functionalityVSAvoidmanufacturing process complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The protection layer is designed to accommodate multiple circuit elements and serve multiple functions simultaneously. The integrated structure provides corrosion protection, electrical insulation, and structural support for various circuit elements, reducing the need for additional dedicated protection structures and simplifying the overall manufacturing process.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

This approach provides a cost-effective solution by eliminating the need for additional processing steps, ensuring protection of redistribution layers without increasing package size or complexity, while maintaining reliability and preventing short circuits.

Implementation Method 1

using solder formation and reflow techniques to create a partial redistribution layer protection layer

Methodology Applied

Scientific EffectReflow:

Implementation Method 2

The solder bump 106 can drift and collapse under heat to melt and flow over the metal interconnect landing pad 104

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentUS10756042B2Multi-layer redistribution layer for wafer-level packaging

Publication Date: 2020.08.25 INTEL CORP

AI summary

Aspects of the embodiments include a semiconductor package that includes a printed circuit board (PCB) and a semiconductor die. The semiconductor die including an interconnect landing pad on an active side of the semiconductor die; a solder material on the interconnect landing pad; a partial redistribution layer on the active side of the semiconductor die; and a protection layer on the partial redistribution layer, the protection layer comprising the solder material. The semiconductor die is electrically connected to the PCB by the solder material on the interconnect landing pad. The partial redistribution layer and the protection layer are separated from the printed circuit board by an air gap.