Development of Flexible Electronics Packaging Technology

Packaging technology plays a critical role in determining the lifespan and cyclic stability of electronic devices. While some existing packaging methods are effective for rigid materials, they often fall short when it comes to packaging flexible electronic devices. The packaging of flexible electronics primarily relies on thin-film packaging techniques, which include both single-layer and multi-layer thin-film packaging. Single-layer thin-film packaging is designed to isolate water and oxygen by forming a dense film on the device's surface. While this method is relatively simple to prepare, it often presents certain defects and struggles to meet the packaging requirements of flexible electronic devices. On the other hand, multi-layer thin-film packaging combines high barrier inorganic materials with flexible organic materials to create organic/inorganic alternating film structures. This innovative approach significantly reduces film defects and stress while providing excellent barrier properties. As a result, it has become the mainstream technology for packaging flexible electronics. Preparation methods for packaging thin films primarily include Plasma-Enhanced Chemical Vapor Deposition (PECVD), Atomic Layer Deposition (ALD), and inkjet packaging technology. PECVD is a plasma-assisted deposition technique widely employed in industries to deposit high-density, well-adhering, and high-quality insulating barrier layer films. Its advantages include low deposition temperature, minimal ion damage, high deposition rates, and large deposition areas. PECVD is commonly used for depositing films such as silicon nitride and silicon oxide. ALD is a method that involves pulsing alternating precursors into a reaction chamber to chemically adsorb and react on a substrate, forming a thin film. ALD enables precise control of film thickness by regulating the number of reaction cycles. It demands less uniformity in the reaction process, facilitates large-area uniform film deposition, and offers excellent repeatability. ALD can be utilized to deposit various types of films, including oxides, metal nitrides, metals, and metal sulfides. Inkjet printing technology entails isolating the printing machine in a nitrogen environment and finely spraying a solution-state material onto the desired location using an inkjet nozzle for encapsulation. This method reduces material wastage, and the equipment investment cost is considerably lower. However, inkjet process encapsulation employs organic low-molecular-weight solutions, which typically exhibit lower barrier properties, lifespan, and uniformity compared to traditional inorganic barrier materials. The advancement of solution processes and inkjet process encapsulation technology is still in the research and development phase.