Buried Coaxial Conductors for High-Speed Interconnections

In May of 1985, the basic work describing buried coaxial conductors in fine-line muitilayer polyimide substrates was reported at the 35th ECC Conference [10]. This unique construction provides a breakthrough technology for controlling electrical crosstalk in closely spaced high-density substrates. Such control is critical for high-speed designs operating in the 1-10-GHz frequency range. That work is expanded here, and a critique On advantages and disadvantages of this technology is provided.