Contactless packaging refers to the concept of using capacitively coupled or inductively coupled structures to connect chips together. That is, to use them as the electrical interfaces for chip-to-package, package-to-socket, and board-to-board interfaces (
connectors). Collectively, these techniques are referred to as “AC Coupled Interconnect,” (ACCI) referring to the lack of a DC connection. These concepts arise from the key realization that a DC connection is not needed to communicate high frequency digital data; a good AC connection suffices. In fact, many high speed chip-to-chip communication standards, such as FiberChannel and Ethernet, use DC blocking capacitors so that the transmitter and receiver do not have to share a common DC supply, making them hot-pluggable. The difference in ACCI is the realization that smaller values of capacitance can be used.