Henkel and the Flexible Display Centre in the US have demonstrated a process for fabricating flexible displays and photovoltaics (PV) using existing production lines for LCD module manufacturing.
The project, funded by the US FlexTech Alliance, aims to reduce future fabrication and capital investment costs for flexible electronics by using debondable laminating adhesives.
The fabrication process involves temporarily bonding a flexible polyethylene naphthalate plastic substrate on a rigid carrier and fabricating amorphous silicon thin film transistors (a-Si TFT) backplane devices. The rigid carrier is used to obtain planarity, dimension stability and lithographic registration. After device fabrication, the flexible substrate is peeled off the carrier, free of adhesive residue and without damage to the active components.
The adhesive preferentially adheres to the carrier when separated and can be removed by high-temperature heating, so the carrier can be reused.
LCD manufacturing
The advantage of such a process allows use of existing manufacturing infrastructure already in place for LCD displays to fabricate flexible large-area displays.
In addition to flexible display backplane fabrication Lirong Bao, technical manager at Henkel, says: 'During the project we also discovered that with fine-tuning of the adhesives for different performance requirements, we have been able to commercial the product for other applications, specifically photovoltaics.'
The lead candidate adhesive formulation, supplied by Henkel, has demonstrated sufficient performance for both 6-inch wafers and Gen two panels at the Flexible Display Centre at Arizona State University.
Spin coating
A technique for making existing LCD manufacturing processes compatible with flexible backplane production is licensed by Taiwan's Prime View International (now E Ink Holdings) from Philips Research.
Standard display glass as used in TFT-LCD plants is coated with a layer of polyimide using a standard spin coating technique used in active matrix LCD production, on to which a TFT matrix is fabricated. A laser separates the polyimide and TFT layers from the glass, and allows the glass to be reused.
Bao will present the project results at the 2012 Flexible Electronics & Displays Conference & Exhibition.
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2012 Flexible Electronics & Displays Conference & Exhibition
The FlexTech conference takes place on 6-9 February 2012 at the Arizona Grand Resort in Phoenix, Arizona, the US
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