Laser-Enabled Advanced Packaging of Ultrathin Bare Dice in Flexible Substrates

Embedding ultrathin semiconductor dice in flexible substrates provides unique capabilities for product designers and makes products such as smart bank cards and radio-frequency identification banknotes possible. Most of the current work in this area is directed toward handling, embedding, and interconnecting the ultrathin chips. Relatively little attention is paid to another critical process step-placing the flexible and very fragile ultrathin die onto the flexible substrate reliably and in a cost-efficient manner, suitable for high throughput assembly. The presented laser-enabled technology for embedding ultrathin dice in a flexible substrate was developed at the Center for Nanoscale Science and Engineering, North Dakota State University, Fargo, ND, to address this problem. The technology has been successfully demonstrated and proven for the fabrication of an RFID tag.