OLED Pad Electrode Protection via Layered Insulating Masks
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Solution Overview
Problem
The existing organic light emitting display (OLED) devices require multiple photomasks for fabrication, leading to reduced productivity and increased costs, as well as deterioration of the pad area during the photolithographic process.
Innovation Solution
The OLED device design includes a substrate with a sub-pixel area and a pad area, featuring a light shielding layer, thin film transistor, light emitting diode, and pad electrodes, where the number of photomasks is reduced by optimizing the fabrication process, and the pad area is protected using a specific layer structure to prevent deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple photomasks are used for fabricating thin film transistors and organic light emitting diode, then fabrication precision is improved, but productivity is reduced and fabrication cost increases
Solution Approach 1:
The patent combines multiple photomask patterns into a single photomask by forming a multi-layer insulating structure where each layer serves as a different functional mask. The first insulating layer acts as a pad electrode mask, the second insulating layer acts as an organic light emitting diode mask, and they are integrated into one fabrication process, thereby improving productivity while maintaining fabrication precision through the layered structure design.
2Manufacturing precision
If multiple photomasks are used for fabricating thin film transistors and organic light emitting diode, then fabrication precision is improved, but fabrication cost increases
Solution Approach 1:
The patent merges multiple photomask requirements into a single photomask fabrication process by creating a multi-layer insulating structure where each layer provides different masking functions. This reduces the number of separate photomasks needed, thereby lowering fabrication costs while maintaining the precision required for different device components through the integrated layered approach.
3Manufacturing precision
If photolithographic process is used for fabricating OLED device, then manufacturing precision is improved, but pad area deterioration occurs
Solution Approach 1:
The patent applies a first insulating layer to the pad area before the photolithographic process, and a second insulating layer to the sub-pixel area. This preliminary protective action prevents the pad area from deterioration during subsequent photolithographic steps, while still allowing precise fabrication of the OLED components in the sub-pixel area through the second insulating layer masking.
Solution Approach 2:
The patent applies different insulating layer configurations to different areas: the first insulating layer covers the pad area for protection, while the second insulating layer covers the sub-pixel area for precise patterning. This local differentiation allows the pad area to be protected from photolithographic damage while maintaining manufacturing precision in the active display area.
Data Source
AI summary
An organic light emitting display device includes a substrate having a sub-pixel area and a pad area, a light shielding layer in the sub-pixel area, a thin film transistor on the light shielding layer in the sub-pixel area, a light emitting diode connected to the thin film transistor, a lower pad electrode in the pad area, a first insulating layer covering the lower pad electrode to expose a portion of the lower pad electrode, an upper pad electrode connected to the lower pad electrode, and a second insulating layer between the first insulating layer and the upper pad electrode, the second insulating layer overlapping the upper pad electrode so that an end portion of the second insulating layer coincides with an end portion of the upper pad electrode.