Middle Frame Isolation Structure for Galvanic Corrosion Control

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Solution Overview

Problem

Galvanic corrosion occurs at the interface between metal middle frames and metal functional members in electronic devices when exposed to humid environments, leading to functional failures and display issues.

Innovation Solution

A middle frame design incorporating a blocking member to isolate the metal frame body from metal functional members, reducing direct contact and preventing galvanic corrosion, while using light metals like magnesium alloys to maintain structural integrity and reduce weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If a metal middle frame is used to reduce device weight, then the weight of the electronic device is reduced, but galvanic corrosion occurs at the interface with metal functional members in humid environments

Engineering Contradiction:
Improveweight of electronic deviceVSAvoidcorrosion resistance at metal interface
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

A blocking member made of non-metallic material (such as plastic or ceramic) is introduced as an intermediary between the metal middle frame and metal functional members. This blocking member prevents direct contact between dissimilar metals, eliminating the galvanic corrosion pathway while still allowing the metal middle frame to be used for weight reduction purposes.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The middle frame structure is transformed into a composite structure by combining metal material for the main frame body with non-metallic blocking members at critical interfaces. This composite approach allows the structure to simultaneously achieve light weight (through metal) and corrosion resistance (through non-metallic blocking members at metal-metal interfaces).

Inventive Principle:
Principle #40Composite materials

2Adaptability or versatility

If metal functional members are assembled on the middle frame to achieve device functions, then the device functionality is enhanced, but direct contact between metals causes galvanic corrosion

Engineering Contradiction:
Improvedevice functionalityVSAvoidgalvanic corrosion at interface
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The blocking member serves as a mediator that allows metal functional members to be assembled on the middle frame while preventing harmful galvanic corrosion. The blocking member is positioned at the interface to electrically isolate the dissimilar metals while still permitting mechanical assembly and functional operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of manufacture

If the middle frame structure is simplified without blocking members, then manufacturing complexity is reduced, but galvanic corrosion occurs leading to functional failures

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidfunctional reliability in humid environment
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The blocking member is designed as a simple, inexpensive component that can be easily manufactured and integrated into the middle frame. Although it adds a small element to the assembly, its low cost and simple structure make the overall manufacturing process remain efficient while providing critical corrosion protection.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 solution effectively minimizes galvanic corrosion, ensuring normal operation of metal keys and display screens in humid conditions, and reduces the overall weight of the electronic device.

Implementation Method 1

galvanic corrosion is prone to occur at a position at which the middle frame fits with the key

Methodology Applied
Scientific EffectGalvanic corrosion:

Data Source

PatentEP4716388A1Middle frame and electronic device
Publication Date: 2026.03.25 HONOR DEVICE CO LTD
  • EP4716388A1 patent drawingFigure 1
  • EP4716388A1 patent drawingFigure 2
  • EP4716388A1 patent drawingFigure 3

AI summary

Embodiments of this application provide a middle frame and an electronic device. The middle frame includes a middle frame body and a blocking member, the middle frame body is made of a metal material, and the middle frame body has a mounting opening in communication with an outside. The mounting opening is configured to mount a metal functional member of the electronic device, and an inner wall of the mounting opening faces the metal functional member. The blocking member is disposed on at least a portion of the inner wall of the mounting opening, and is configured to isolate the middle frame body from the metal functional member. The middle frame provided in the embodiments of this application has a relatively low risk of galvanic corrosion.