Flexible Interconnects with Vertical Displacement for Stretchable Packaging

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current Fan-Out Wafer Level Packaging (FOWLP) technologies use rigid molding compounds and interconnects, resulting in inflexible substrates and interconnects that cannot adequately accommodate the mechanical stress of bending or stretching, limiting their application in flexible and portable electronic devices.

Innovation Solution

The development of flexible devices with vertically varying interconnects, such as VeRzag and vertically corrugated interconnects, which are integrated into a flexible FOWLP process, allowing for high-density, fine-pitch interconnects that can stretch and bend without compromising mechanical integrity, using techniques like thermally removable adhesive layers and stress buffer layers to form non-planar surfaces for interconnect formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If rigid molding compounds are used for FOWLP, then manufacturing precision and structural stability are improved, but flexibility and adaptability to mechanical stress deteriorate

Engineering Contradiction:

Improveinterconnect pitch precisionVSAvoidflexibility

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent replaces rigid molding compounds with flexible substrates made of thin film materials that can bend and stretch while maintaining interconnect functionality. The flexible substrate acts as a thin film that accommodates mechanical stress without compromising the precision of fine-pitch interconnects, directly resolving the contradiction between rigidity for manufacturing precision and flexibility for adaptability.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent changes the physical parameters of the substrate material from rigid to flexible, enabling the substrate to dynamically adjust its mechanical properties. This parameter change allows the substrate to maintain dimensional stability during manufacturing while providing flexibility for bending and stretching applications, thus resolving the contradiction between manufacturing precision and flexibility.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If rigid interconnects are used, then electrical performance and manufacturing precision are improved, but mechanical reliability under bending stress deteriorates

Engineering Contradiction:

Improveinterconnect geometry precisionVSAvoidmechanical reliability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent introduces vertically corrugated interconnect structures with curved profiles instead of straight rigid lines. These corrugated interconnects can bend and deform elastically under mechanical stress while maintaining their electrical connectivity and geometric precision, resolving the contradiction between rigid structure for manufacturing precision and flexibility for mechanical reliability.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent transforms static rigid interconnects into dynamic flexible interconnects that can adapt their shape in response to mechanical stress. The flexible interconnects maintain their electrical function while dynamically adjusting their physical configuration during bending and stretching, thus improving mechanical reliability without sacrificing manufacturing precision.

Inventive Principle:

Principle #15Dynamics

3Productivity

If fine-pitch interconnects are implemented, then device density and functionality are improved, but susceptibility to mechanical stress and damage increases

Engineering Contradiction:

Improvedevice densityVSAvoidresistance to mechanical stress

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent uses flexible substrates to support fine-pitch interconnects, allowing the entire interconnect structure to bend and stretch without breaking. This flexible support mechanism enables high device density with fine-pitch interconnects while protecting them from mechanical damage, resolving the contradiction between productivity and reliability.

Inventive Principle:

Principle #30Flexible shells and thin films

4Adaptability or versatility

If flexible substrates are used, then adaptability to non-planar surfaces is improved, but manufacturing precision and structural stability deteriorate

Engineering Contradiction:

ImproveflexibilityVSAvoidinterconnect pitch precision

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent changes the material parameters of the substrate to achieve optimal balance between flexibility and dimensional stability. By selecting specific flexible materials with appropriate mechanical properties, the substrate can bend and stretch while maintaining sufficient dimensional stability during manufacturing processes to ensure precise interconnect pitch, thus resolving the contradiction between adaptability and manufacturing precision.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11538764B2Flexible and stretchable interconnects for flexible systems

Publication Date: 2022.12.27 RGT UNIV OF CALIFORNIA

AI summary

A flexible device includes: (1) a flexible substrate; and (2) an interconnect disposed over the flexible substrate, wherein the interconnect has a varying vertical displacement along its length, relative to a top surface of the flexible substrate.