The design of some novel 0.050-in. grid high-density circuit pack-to-backplane connectors

Three high-density connectors (HDCs) are discussed. All provide a butt connection to the backplane on an orthogonal 0.050-in grid (80 I/Os per inch of circuit pack height). All connectors have four columns of contacts, yielding 560 I/Os on an 8-in-high circuit pack. Two of these connectors, the circuit pack header and the printed/molded connector, connect to an array of 0.050-in-grid gold-plated pads on the backplane and the circuit pack through a unidirectional conductive elastomer called the conductive polymer interconnect (CPI). The sheet of CPI elastomer conducts in the thickness direction only. The other connector, called the flex connector, uses a highly compliant, high temperature-resistant elastomer to make direct metal-to-metal connection to the arrays of gold-plated pads on the backplane and the circuit pack. A battery of reliability tests has been conducted on the HDC system. The flex connector exhibited stable electrical resistance. The test results on the other two connectors using CPI have yielded information on how to improve the connector designs