Epoxy Adhesive for Copper Foil Shielding Joints
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Solution Overview
Problem
The existing electromagnetic shielding materials with copper foil composites connected in a longitudinal direction often suffer from defects such as bulges or concave shapes due to inadequate adhesion strength and increased rigidity at the connected parts, leading to shape changes in the shielded structure during the shielding process.
Innovation Solution
The use of an epoxy-based adhesive with flexibility-providing resins like nitrile butadiene rubber, natural rubber, or styrene butadiene rubber, applied to the overlapped parts of copper foil composites, ensures a specific adhesion strength and flexibility, preventing defects by maintaining adhesion even at elevated temperatures and controlling the thickness and rigidity of the adhesive layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive tape or acrylic resin is used to connect copper foil composites, then the connection is achieved, but the adhesion strength decreases at elevated temperatures causing concave defects
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive by using epoxy resin instead of acrylic resin or adhesive tape. Epoxy resin has superior thermal stability and maintains adhesion strength at elevated temperatures up to 150°C, resolving the temperature resistance issue while preserving connection strength.
Solution Approach 2:
The patent uses a composite adhesive system combining epoxy resin with flexibility-providing resins (nitrile butadiene rubber, natural rubber, styrene butadiene rubber, butadiene rubber, ethylene propylene rubber, isoprene rubber, urethane rubber, or acrylic rubber). This composite material achieves both high adhesion strength and flexibility, preventing both concave and bulge defects.
2Strength
If the adhesive layer is made thicker to improve adhesion, then connection strength increases, but rigidity and thickness increase causing bulge defects
Solution Approach 1:
The patent optimizes the adhesive layer thickness parameter to 1-6 mm, which provides sufficient adhesion strength while preventing excessive rigidity. This controlled thickness parameter resolves the contradiction between connection strength and shape stability.
Solution Approach 2:
The patent applies flexibility-providing resins to the adhesive composition, which locally modify the adhesive layer properties to provide flexibility where needed while maintaining overall adhesion strength. This local quality enhancement prevents bulge defects without sacrificing connection strength.
3Length of stationary object
If multiple copper foil composites are connected to extend length, then the shielding material length is sufficient, but defects appear at connected parts
Solution Approach 1:
The patent extracts the problematic adhesive materials (adhesive tape and acrylic resin) and replaces them with epoxy resin-based adhesive. This extraction of the harmful element (inadequate adhesive) and replacement with a superior material eliminates the source of surface flatness defects at connected parts.
Solution Approach 2:
The epoxy resin-based adhesive acts as an intermediary material that bonds copper foil composites together while maintaining surface flatness. The adhesive mediates between the rigid copper foil composites, providing a flexible yet strong connection that prevents visible defects at joints.
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 solution effectively prevents shape defects in the shielded structure by ensuring a minimum adhesion strength of 1.5 N/mm at 150°C and maintaining flexibility, thereby preventing concave and bulge defects during the shielding process.
Implementation Method 1
an overlapped part of the copper foil composites is adhered with an epoxy based adhesive comprising as main components an epoxy resin and one or more of flexibility providing resins
Data Source
Figure 1~2
Figure 3(a)~4(c)
Figure 5
AI summary
An electromagnetic shielding material 50 comprising a plurality of copper foil composites 10 connected together in a longitudinal direction L, the composite having a copper foil 2 and a resin film 4 which are laminated, wherein an overlapped part 50k of the copper foil composites is adhered with an epoxy based adhesive 6 comprising as main components an epoxy resin and one or more of flexibility providing resins selected from the group consisting of nitrile butadiene rubber, natural rubber, styrene butadiene rubber, butadiene rubber, ethylene propylene rubber, isoprene rubber, urethane rubber and acrylic rubber, and wherein the epoxy based adhesive disposed at the overlapped part of the copper foil composites has a length LA in the longitudinal direction of 1 to 6 mm.