EMI Shielding Film Rolling Uneven Surface Adhesion
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Solution Overview
Problem
Existing EMI shielding films for flexible circuit boards suffer from delamination and blistering due to insufficient adhesive holding capacity, leading to grounding failures and interference issues at high temperatures.
Innovation Solution
An EMI shielding film with a rolling uneven surface and convex conductor particles on the second surface, combined with an adhesive film layer, ensures strong puncture force and peel strength, preventing delamination and blistering by effectively grounding the shielding layer during lamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shielding layer with a rough surface is used to puncture the adhesive film layer during lamination, then grounding contact is achieved, but adhesive holding capacity is insufficient causing delamination and blistering
Solution Approach 1:
The invention creates local quality differentiation on the shielding layer surface by forming convex conductor particles on protrusions and providing recesses for adhesive holding. The surface is not uniformly rough but has specific localized features: protrusions with conductor particles for puncture/grounding and recesses for adhesive retention, resolving the contradiction between grounding contact and adhesive holding capacity
Solution Approach 2:
The shielding layer surface is pre-formed with a specific topography (protrusions and recesses) and conductor particles before lamination. This preliminary structure ensures that during lamination, the protrusions can effectively puncture the adhesive film to contact the ground layer, while the recesses are already positioned to hold adhesives, preventing delamination and blistering
2Reliability
If the shielding layer punctures the adhesive film layer to contact the ground layer, then grounding is achieved, but delamination and blistering occur at high temperature
Solution Approach 1:
The invention provides beforehand cushioning by creating recesses on the shielding layer surface that are specifically designed to hold adhesives. This pre-prepared adhesive retention structure cushions against the thermal expansion and stress at high temperatures, preventing delamination and blistering while maintaining the grounding function achieved through protrusion puncture
3Manufacturing precision
If a flat shielding layer surface is used, then adhesive distribution is uniform, but puncture force is insufficient to contact the ground layer
Solution Approach 1:
The invention introduces asymmetry to the shielding layer surface by creating an uneven topography with protrusions and recesses instead of a flat surface. The protrusions provide concentrated puncture force to contact the ground layer, while the overall distribution remains controlled. This asymmetric structure resolves the contradiction between uniform adhesive distribution and sufficient puncture force
Data Source
AI summary
Provided are an Electromagnetic Interference (EMI) shielding film, a circuit board including the EMI shielding film, and a preparation method for the EMI shielding film. The EMI shielding film includes a shielding layer and an adhesive film layer, wherein the shielding layer includes a first surface and a second surface opposite to each other; the second surface is a rolling uneven surface; convex conductor particles are also formed on the rolling uneven surface; and the second surface of the shielding layer is provided with the adhesive film layer, so the adhesive film layer of the EMI shielding film will extrude adhesive materials into recesses of the second surface in a lamination process, the adhesive holding capacity is increased, and delamination and blister of board is unlikely to occur. Moreover, the rolling uneven surface also has conductor particles with a certain height, so it can be ensured that the shielding layer smoothly punctures the adhesive film layer in the lamination process, reliable grounding is achieved, and the practicality is strong.