Dual-Layer Insulation Coating for Card Tray Scratch Resistance

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Solution Overview

Problem

Damaged surface insulation coatings on card trays in smartphones lead to electric conduction issues, affecting communication signals and causing poor signal quality or failure to recognize SIM cards.

Innovation Solution

A card tray design featuring two insulation layers, where the first layer has a higher hardness than the second, comprising a metal base layer, an intermediate mixed layer of metal and chemical compounds, and a diamond-like carbon coating, with the second layer being a polymer coating to protect against scratches and improve insulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single insulation coating is applied on the card tray base, then the insulation effect is improved, but the coating is easily damaged by burrs or sharp edges causing electric conduction

Engineering Contradiction:
Improveinsulation effectVSAvoidscratch resistance
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The insulation coating is divided into two separate layers: a first insulation layer directly on the card tray base and a second insulation layer on top of the first. This segmentation allows each layer to have different properties - the first layer provides hardness and scratch resistance while the second layer provides insulation, resolving the contradiction between insulation effectiveness and scratch resistance

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The first insulation layer uses a composite structure with a metal base layer and an insulation coating layer, where the metal base layer enhances hardness and scratch resistance while the insulation coating layer provides electrical insulation. This composite material approach allows the coating to resist damage from burrs and sharp edges while maintaining insulation effectiveness

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If the first insulation layer is made with high hardness materials, then scratch resistance is improved, but the insulation effect may be compromised

Engineering Contradiction:
Improvescratch resistanceVSAvoidinsulation effect
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The insulation system is segmented into two functional layers: the first insulation layer (with metal base layer and insulation coating) provides hardness and scratch resistance, while the second insulation layer provides the primary insulation effect. This segmentation allows each layer to optimize for its specific function without compromising the other

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the coating structure have different properties tailored to local requirements: the metal base layer has high hardness for scratch resistance, the insulation coating layer has insulating properties, and the second insulation layer provides additional insulation. This local quality differentiation resolves the contradiction between hardness and insulation effect

Inventive Principle:
Principle #3Local quality

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 dual-layer insulation effectively prevents scratches and maintains signal quality by reducing electric conduction and ensuring the mobile terminal can recognize the card, even with burrs or sharp edges, thereby enhancing the card recognition effect.

Implementation Method 1

the insulation coating is a mixed layer of a metal, a chemical compound of the metal, and a diamond-like carbon material

Methodology Applied
Scientific EffectDiamond-like carbon: Diamond-like Carbon

Implementation Method 2

the intermediate layer is a mixed layer of a metal and a chemical compound of the metal

Methodology Applied
Scientific EffectMixed layer formation: Composite Materials

Implementation Method 3

a surface insulation coating of a card tray (or referred to as a card slot) is damaged, and consequently, an electric conduction phenomenon occurs on the card tray

Methodology Applied
Scientific EffectElectrical insulation: Electrical Resistance

Data Source

PatentEP3319181B1Card holder and preparation method thereof, and mobile terminal
Publication Date: 2019.12.25 HUAWEI TECH CO LTD
  • EP3319181B1 patent drawingFigure 1~2
  • EP3319181B1 patent drawingFigure 3
  • EP3319181B1 patent drawingFigure 4

AI summary

A card tray, a method for preparing a card tray, and a mobile terminal are disclosed. The card tray (10) includes a card tray base (11), a first insulation layer (12) disposed on the card tray base (11), and a second insulation layer (13) covering the first insulation layer (12), where hardness of the first insulation layer (12) is higher than that of the second insulation layer (13). In the technical solution, two insulation coatings are disposed on the card tray base (11) to protect the card tray base (11), and hardness of the first insulation layer (12) is set to be higher than that of the second insulation layer (13). When burrs or sharp parts on a card pierce the second insulation layer (13), the first insulation layer (12) can block the burs or the sharp parts, thereby preventing an insulation coating on the card tray base (11) from being scratched by the burs. Therefore, insulating properties of the card tray are improved effectively, and therefore, an effect of recognizing the card by the mobile terminal is improved; and cases in which the mobile terminal cannot recognize the card due to scratches on the insulation coating of the card tray and electric conduction of the card tray are reduced effectively.