Technical Abstracts
In Case You Missed It
Chiplets
“Goodbye, Motherboard. Hello, Silicon-Interconnect Fabric”

Authors: Puneet Gupta, Ph.D. and Subramanian S. Iyer, Ph.D.

Abstract: The need to make some hardware systems smaller and others bigger has been driving innovations in electronics for a long time. The former can be seen in the progression from laptops to smartphones to smart watches to hearables and other “invisible” electronics. The latter defines today’s commercial data centers – megawatt-devouring monsters that fill purpose-built warehouses around the world. Interestingly, the same technology is limiting progress in both arenas, though for different reasons. The culprit is the printed circuit board. And the solution is to get rid of it. The authors’ research shows PCBs could be replaced with silicon. Such a move would lead to smaller, lighter-weight systems for wearables and other size-constrained gadgets, and to incredibly powerful high-performance computers. This all-silicon technology, called silicon-interconnect fabric, allows bare chips to be connected directly to wiring on a separate piece of silicon. Unlike connections on a printed circuit board, the wiring between chips on the fabric is just as small as wiring within a chip. Many more chip-to-chip connections are thus possible, and those connections are able to transmit data faster while using less energy. (IEEE Spectrum, Sept. 24, 2019)

Printed Electronics
“Three-Dimensional Curvy Electronics Created Using Conformal Additive Stamp Printing”

Authors: Kyoseung Sim, Ph.D., et al.

Abstract: Electronic devices are typically manufactured in planar layouts, but many emerging applications, from optoelectronics to wearables, require three-dimensional curvy structures. However, the fabrication of such structures has proved challenging, due to the lack of an effective manufacturing technology. The authors show conformal additive stamp (CAS) printing technology can be used to reliably manufacture 3-D curvy electronics. CAS printing employs a pneumatically inflated elastomeric balloon as a conformal stamping medium to pick up pre-fabricated electronic devices and print them on curvy surfaces. To illustrate the capabilities of the approach, it is used to create various devices with curvy shapes: silicon pellets, photodetector arrays, electrically small antennas, hemispherical solar cells and smart contact lenses. It is also shown that CAS printing can be used to print onto arbitrary 3-D surfaces. (Nature)

PTH Reliability
“Failure Analysis on Cracking of Blind and Buried Vias of Printed Circuit Board for High-End Mobile Phones”

Authors: Jie Tang, Yi Gong and Zhen-Guo Yang

Abstract: Cracking of blind and buried vias of printed circuit boards for smartphones was encountered, leading to defects such as display problems like scrambled display or no display during service. To find the root causes of the failure, comprehensive failure analysis was performed on the PCBAs and PCBs of the failed smartphones. Tests performed included macrograph and micrograph observation, chemical compositions analysis, thermal performance testing and blind via pull-off experiment. Blind via cracking was found to be the main reason for the scrambled display or no display conditions, and an incomplete cleaning process before copper plating was the root cause of the blind vias cracking. (Soldering & Surface Mount Technology, vol. 31 no. 4, Sept. 2, 2019)

This column provides abstracts from recent industry conferences and company white papers. Our goal is to provide an added opportunity for readers to keep abreast of technology and business trends.