Composite Laminate for Mobile Device Housings

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Solution Overview

Problem

Existing composite laminates for mobile electronic device housings lack the necessary combination of high flexural modulus and lightweight, thin profiles, as they often compromise on structural rigidity and stiffness.

Innovation Solution

A composite laminate structure comprising a woven fabric layer made from poly(p-phenylene terephthalamide) or poly(m-phenylene isophthalamide) fibers, combined with high modulus unidirectional fabric layers also made from these polymers, embedded in a thermoset resin such as epoxy or polyimide, providing a balanced stiffness and weight ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional composite laminates are used for mobile electronic device housings, then structural rigidity and stiffness can be achieved, but the weight and thickness increase

Engineering Contradiction:
Improvestructural rigidityVSAvoidweight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent employs a composite laminate structure combining woven fabric layers and unidirectional fabric layers made from high-performance polymers (poly(p-phenylene terephthalamide) and poly(m-phenylene isophthalamide)) to achieve superior strength-to-weight ratio. This composite construction provides the necessary structural rigidity while maintaining lightweight characteristics suitable for mobile electronic devices.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies different fabric configurations (woven vs. unidirectional) and fiber orientations in specific layers to optimize local structural properties. The unidirectional layers provide enhanced stiffness in critical directions, while woven layers offer multidirectional strength, creating a locally optimized structure that maximizes rigidity where needed while minimizing overall weight.

Inventive Principle:
Principle #3Local quality

2Strength

If conventional composite laminates are used for mobile electronic device housings, then structural rigidity can be achieved, but the thickness increases

Engineering Contradiction:
Improvestructural rigidityVSAvoidthickness
Core Design Contradiction:
StrengthVSLength of stationary object

Solution Approach 1:

The patent utilizes a multi-layer composite laminate with specific combinations of woven and unidirectional fabric layers, each contributing to structural rigidity. This composite architecture achieves high stiffness-to-thickness ratio, providing necessary structural performance in a thin profile suitable for modern mobile electronic devices.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent employs unidirectional fabric layers with fibers oriented in specific directions to maximize stiffness in critical load-bearing directions while minimizing material usage in other dimensions. This directional fiber alignment allows the laminate to achieve high structural rigidity with reduced thickness compared to isotropic conventional composites.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Length of stationary object

If thin profile composite laminates are used for mobile electronic device housings, then lightweight and thin design is achieved, but structural rigidity and resistance to deflection are compromised

Engineering Contradiction:
ImprovethicknessVSAvoidresistance to deflection
Core Design Contradiction:
Length of stationary objectVSStrength

Solution Approach 1:

The patent employs a sophisticated composite laminate structure with alternating woven and unidirectional fabric layers made from high-modulus polymers. This composite construction provides exceptional stiffness and resistance to deflection despite the thin profile, as the layered architecture with optimized fiber orientations maximizes structural efficiency at minimal thickness.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent utilizes unidirectional fabric layers with strategically oriented fibers to concentrate structural strength in critical directions while maintaining thin overall thickness. This dimensional optimization allows the laminate to resist deflection and bending forces effectively despite its thin profile, achieving high flexural rigidity in a space-efficient design.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP3122551B1Fiber-reinforced composite laminate and articles made therefrom
Publication Date: 2021.04.21 DUPONT SAFETY & CONSTRUCTION INC
  • EP3122551B1 patent drawingFigure 1
  • EP3122551B1 patent drawingFigure 2

AI summary

A composite laminate consisting essentially of (a) a layer of a woven fabric as the top layer; and (b) at least one layer of a unidirectional fabric wherein the composite laminate has a total thickness of from 0.1 mm to 2 mm; the woven fabric (a) comprises fibers produced from poly(p phenylene terephthalamide) homopolymer, poly(p-phenylene terephthalamide) copolymer, poly(m-phenylene isophthalamide) homopolymer, poly(m-phenylene isophthalamide) copolymer, polysulfonamide homopolymer, polysulfonamide copolymer, and mixture thereof; the unidirectional fabric (b) comprises high modulus fibers produced from poly(p phenylene terephthalamide) homopolymer or poly(p-phenylene terephthalamide) copolymer, the fibers having a tensile modulus of at least 100 GPa; and the woven fabric (a) and the unidirectional fabric (b) each independently comprise a thermoset resin selected from epoxy, polyimide, and mixtures thereof. Also disclosed are articles comprising the composite laminates, wherein the articles are housings or protective covers for mobile electronic devices such as a handheld computer, a tablet computer, a mobile phone, an e-reader, a portable game device, a portable media player or a digital camera.