Adhesion and Transparency Enhancement between Flexible Polyimide-PDMS Copolymerized Film and Copper Foil for LED...

Area of Science:

• Materials Science
• Polymer Chemistry
• Surface Engineering

Background:

• LED transparent screens require flexible substrates like polyimide (PI) copper-clad laminates.
• Differences in thermal expansion and surface energy between PI and copper create interfacial instability, limiting screen lifespan.
• Aminopropyl-terminated polydimethylsiloxane (PDMS) is explored to improve PI-copper interfacial adhesion.

Purpose of the Study:

• To synthesize novel polyimide (PI) films with enhanced adhesion and optical properties for flexible LED transparent screen applications.
• To investigate the effect of incorporating varying amounts of PDMS on the interfacial adhesion and optical characteristics of PI films bonded to copper foil.

Main Methods:

• Synthesis of PI films using diamine monomers with trifluoromethyl and sulfone groups, and a dianhydride monomer, incorporating 0-5 wt% PDMS.
• Analysis of optical properties using UV-Vis spectroscopy.
• Evaluation of thermal properties (T_{d 5%}, T_{d 10%}, Tg).
• Measurement of PI-copper interfacial adhesion using a 180° peel assay.

Main Results:

• Synthesized PI films exhibited transmittance over 80% at 450 nm.
• Incorporation of PDMS led to a gradual decrease in thermal stability (T_{d 5%}, T_{d 10%}, Tg) with increasing PDMS content.
• PI films with 3 wt% PDMS showed the highest peel adhesion strength, reaching 0.98 N/mm and 0.85 N/mm.

Conclusions:

• The addition of PDMS effectively enhances the interfacial adhesion between PI films and copper foil.
• The synthesized PI films with PDMS show promising potential for improving the durability and performance of LED transparent screens.
• Further optimization of PDMS content is crucial to balance adhesion enhancement with thermal stability.