Flexible Circuit Shielding Adhesion via Composite Insulator
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Solution Overview
Problem
Existing flexible printed circuit boards (FPCs) with electromagnetic shielding materials face challenges in maintaining long-term shielding effectiveness during repeated bending or sliding, primarily due to inadequate adhesion between the electromagnetic shielding material and the insulator film, along with issues in flexibility, flame retardance, and electrical insulation reliability.
Innovation Solution
A conductive-layer-integrated flexible printed circuit board is designed with an electromagnetic-shielding conductive layer, an insulator film containing a binder polymer and spherical organic beads, and a wiring-pattern-equipped film, where the insulator film also includes fine particles of phosphorus, aluminum, or magnesium, and is made from a thermosetting resin composition, enhancing adhesion and flexibility while reducing warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electromagnetic shielding materials are used on FPCs, then electromagnetic shielding effect is achieved, but adhesion between the shielding material and insulator film deteriorates during repeated bending and sliding
Solution Approach 1:
The insulator film is constructed as a composite material containing a binder polymer and spherical organic beads. This composite structure provides both the adhesion necessary to maintain shielding effectiveness and the flexibility required for repeated bending without delamination
Solution Approach 2:
The insulator film incorporates spherical organic beads with specific physical parameters (size, shape, and material properties) that modify the film's mechanical characteristics. These parameter changes enable the film to maintain adhesion while accommodating repeated bending and sliding movements
2Ease of operation
If the insulator film is made flexible to withstand repeated folding, then flexibility is improved, but adhesion between the electromagnetic shielding material and insulator film deteriorates
Solution Approach 1:
The composite insulator film combines a binder polymer matrix with dispersed spherical organic beads. The polymer matrix provides flexibility for repeated folding, while the composite structure maintains adhesion strength through the synergistic interaction between the binder and filler particles
3Strength
If the insulator film contains spherical organic beads, then adhesion and flexibility are improved, but manufacturing complexity increases
Solution Approach 1:
The spherical organic beads are incorporated as a straightforward compositional parameter change in the insulator film formulation. Despite the added material component, the manufacturing process remains relatively simple, involving standard mixing and lamination techniques already used in FPC production
Data Source
AI summary
A conductive-layer-integrated flexible printed circuit board includes: (A) an electromagnetic-shielding conductive layer; (B) an insulator film; and (C) a wiring-pattern-equipped film the electromagnetic-shielding conductive layer (A), the insulator film (B), and the wiring-pattern-equipped film (C) being laminated in this order, the insulator film (B) containing at least (a) a binder polymer and (b) spherical organic beads.