Flexible Substrate Assembly with Integrated Passive Components

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Solution Overview

Problem

Current interposer substrates for wearable devices and IoT devices face challenges with bulkiness, rigidity, cost, and reliability, particularly with FR4-based PCBs and Si-based interposers, which are costly and fragile, and fail to efficiently integrate passive circuit elements.

Innovation Solution

A carbon or metal-based substrate with a coefficient of thermal expansion matching silicon is used, integrating passive circuit components and IC dies with metal-filled vias, formed from materials like NILO alloy 42, Invar, and stainless steel, with a conformal dielectric layer and patterned metal layers, allowing for efficient interconnection and reduced thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If FR4-based PCB substrates are used, then electrical routing interconnect is provided, but the substrate is thick (1.5-2.5mm), rigid, and has large surface area

Engineering Contradiction:

Improvestructural stabilityVSAvoidsubstrate thickness

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent changes the material parameters by substituting FR4 with thin-film polyimide, transforming the substrate from thick and rigid to thin and flexible. This parameter change enables the substrate to achieve both mechanical stability and flexibility while reducing thickness from millimeters to micrometers scale

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structure by combining thin-film polyimide with metal traces and passive components integrated into a multi-layer configuration. This composite approach provides structural integrity while maintaining flexibility and reducing overall substrate thickness

Inventive Principle:

Principle #40Composite materials

2Ease of operation

If polyimide-based flex substrates are used, then flexibility is improved, but the substrate is thicker than 200 microns and only provides electrical traces

Engineering Contradiction:

ImproveflexibilityVSAvoidsubstrate thickness

Core Design Contradiction:

Ease of operationVSVolume of moving object

Solution Approach 1:

The patent applies parameter changes by reducing substrate thickness to below 200 microns through thin-film polyimide construction, while simultaneously enhancing functionality by integrating passive components to replace traditional PCBA assemblies

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements multi-functionality by integrating passive components (resistors, capacitors, inductors) directly into the flexible substrate, enabling it to serve both as mechanical support and functional circuit carrier, replacing separate PCBA assemblies

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of manufacture

If glass substrates are used, then alternative to Si is provided, but reliability issues occur due to fragility at small thicknesses

Engineering Contradiction:

Improvematerial availabilityVSAvoidmechanical reliability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies parameter changes by substituting fragile glass with flexible thin-film polyimide, transforming the mechanical properties from brittle to ductile while maintaining thin profile and enabling integration of passive components

Inventive Principle:

Principle #35Parameter changes

4Reliability

If conventional PCBA assemblies are used, then electrical interconnection is provided, but the surface area is large and integration efficiency is low

Engineering Contradiction:

Improveelectrical interconnectionVSAvoidsubstrate surface area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent implements merging by combining passive components, active components, and interconnect structures into a single integrated flexible substrate assembly, eliminating the need for separate PCBA assemblies and reducing overall surface area

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent applies multi-functionality by designing the flexible substrate to serve multiple functions: mechanical support, electrical interconnection, signal routing, and passive component integration, replacing multiple separate assemblies with a single universal platform

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 results in a thin, flexible, cost-effective, and reliable substrate assembly with improved signal integrity and reduced weight, suitable for 2.5D/3D packaging, enabling efficient integration of passive components and IC dies.

Implementation Method 1

depositing alumina or a multilayer dielectric that has low permeability to oxygen and moisture on a paper substrate

Methodology Applied

Scientific EffectPermeation: Permeation

Data Source

PatentUS9318466B2Method for electronic circuit assembly on a paper substrate

Publication Date: 2016.04.19 GLOBALFOUNDRIES US INC

AI summary

A methodology for a thin, flexible substrate having integrated passive circuit elements, and the resulting device are disclosed. Embodiments may include integrating one or more passive circuit components on a first or second surface of a substrate, and interconnecting one or more integrated circuit (IC) dies on a second surface of the interposer to the one or more passive circuit components with one or more metal-filled vias between the first and second surfaces, the first and second surfaces being opposite surfaces of the substrate.