Sputtered anti-reflection layer on transparent polyimide - substrate improves adhesion strength to - copper layer: effects of layer thickness and sputtering power.

In order to shield the electronic circuits on a transparent polyimide (PI) substrate, an anti-reflection (AR) layer was deposited on a PI film via DC reactive magnetron sputtering. The effects of sputtering power and thickness of AR layer on the optical property and adhesion strength of the PI were investigated. The composition of the AR layer influences the bonding between layers. Sufficient thickness of the AR layer is essential to strengthen the adhesion between the PI and copper (Cu) layers. The sputtered AR layer on the PI also improves the barrier property for water vapor. The AR layer-sputtered PI substrates remain transparent and exhibit high peel strength to the Cu layer, suggesting their potential applications as reliable transparent substrates for modern electronic devices.

Anti-reflection Layer-Sputtered Transparent Polyimide Substrate with Reliable Adhesion Strength to the Copper Layer.

Parameters of DC-reactive magnetron sputtering are optimized to deposit anti-reflection (AR) layers on transparent polyimide (PI) substrates, followed by the deposition of the conductive copper layer, to fabricate practically reliable composite films as advanced flexible circuits. When the deposition thickness is controlled and the gas composition during sputtering is adjusted, the resultant AR layer-coated PI film exhibits low reflectance and reveals improved adhesion strength to the copper layer. The adhesion reliability tests confirm that the peel strength between the PI film and the deposited layers could be further improved after thermal processing due to the formation of a worm-like morphology for better mechanical interlocking with layers. The facile sputtering process successfully fabricates a reliable substrate material with low reflectance and sufficient adhesion strength to copper for application as flexible printed circuits.