Metal-Plastic Shell Bonding via Porous Oxide Layer
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Solution Overview
Problem
Existing methods for preparing metal-plastic composite shells, such as those for electronic devices, suffer from poor connection force between metal and plastic, lack of wear-resist and drop-resist properties, and inadequate acid and alkali resistance, with adhesives failing to provide robust and durable joints.
Innovation Solution
A shell comprising a metal shell body, a plastic part made of resin, and an oxide layer with nanopores and corrosion pores formed by anodizing and etching, respectively, where the resin fills these pores to enhance bonding and provide improved mechanical and chemical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is used to join metal and plastic, then the metal and plastic can be connected, but the connection force is poor and the joint lacks wear-resist and drop-resist properties
Solution Approach 1:
The patent applies porous materials by forming a porous oxide layer on the metal surface through anodization, creating nanopores that penetrate deep into the metal substrate. This porous structure enables the resin to infiltrate and form strong mechanical interlocking, achieving superior connection force and reliability compared to adhesive bonding. The porous oxide layer acts as an anchor for the resin, providing both strength and durability against wear and impact.
Solution Approach 2:
The patent creates a composite material system consisting of metal substrate, porous oxide layer, and resin matrix. This composite structure combines the advantages of metal (strength, durability) with resin (corrosion resistance, aesthetic properties). The intermediate oxide layer serves as a bonding interface that chemically and mechanically connects the metal and resin, forming a unified composite material with enhanced overall performance.
2Ease of manufacture
If adhesive is used to join metal and plastic, then the components can be assembled, but the joint has poor acid-resist and alkali-resist and cannot undergo surface treatment
Solution Approach 1:
The porous oxide layer performs multiple functions simultaneously: it serves as a bonding interface for the resin, provides corrosion resistance, and enables subsequent surface treatments. The oxide layer is inherently resistant to acids and alkalis, and this resistance is transferred to the entire joint structure. The resin-filled pores create a self-reinforcing system that maintains chemical resistance while providing structural integrity.
Solution Approach 2:
The patent changes the chemical and physical parameters of the metal surface by forming an oxide layer with specific pore size distribution (10-100nm nanopores). This parameter change transforms the surface properties to be more compatible with resin bonding while maintaining chemical resistance. The controlled porosity allows resin penetration without compromising the protective oxide structure.
3Ease of manufacture
If conventional metal surface treatment is used, then metal preparation is simple, but the connection force with resin is insufficient
Solution Approach 1:
The patent performs preliminary action by forming a porous oxide layer on the metal surface before resin application. This pre-treatment creates a surface structure specifically optimized for resin bonding, with nanopores that will be filled by the resin during injection molding. The preliminary anodization process prepares the surface to maximize mechanical interlocking and chemical bonding with the resin, ensuring strong connection force from the outset.
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 results in a shell with enhanced wear-resist, drop-resist, and corrosion-resist properties, achieving stronger connection forces between metal and plastic without additional adhesives, while maintaining the appearance and size integrity of the metal shell, and allowing for easier resin injection molding.
Implementation Method 1
an oxide layer formed between the metal body and the plastic part, joining the plastic part to the metal shell body, wherein the oxide layer contains corrosion pores having an average pore size of about 200nm to about 2000nm in the surface contacting the plastic part, and nanopores having a pore size of about 10 to 100nm in the surface contacting the metal shell body; and a part of the resin is filled in the nanopores and corrosion pores
Implementation Method 2
an oxide layer formed between the metal body and the plastic part, joining the plastic part to the metal shell body
Implementation Method 3
S1: anodizing at least a part of the surface of a metal shell body to form an oxide layer, wherein the oxide layer is formed with nanopores
Implementation Method 4
S2: immersing the resulting metal shell body in step S1 in above mentioned etching solution, to form corrosion pores in at least a part of the outer surface of the oxide layer
Implementation Method 5
a part of the resin is filled in the nanopores and corrosion pores
Data Source
Figure 1~3a
Figure 3b
Figure 4~5
AI summary
A shell, a method of preparing the shell and an electronic product comprising the shell are provided. The shell may comprise: a metal shell body; a plastic part made of a resin; and an oxide layer formed between the metal body and the plastic part, joining the plastic part to the metal shell body, wherein the oxide layer contains corrosion pores having an average pore size of about 200nm to about 2000nm in the surface contacting the plastic part, and nanopores having a pore size of about 10 to 100nm in the surface contacting the metal shell body; and a part of the resin is filled in the corrosion pore and corrosion pore.