Design and development of high capacity spaceborn memory modules in the high density interconnect (HDI) technology for the tropical rainfall measuring mission (TRMM)

A new technology, a planar multi chip module (MCM) employing thin film polyimide/Cu-Ti interconnects was designed, fabricated and successfully inserted into the Tropical Rainfall Measuring Mission (TRMM). The design contains 25 Hitachi 128 k×8 Static Random Access Memory (SRAM) die arranged in a 512 k×40 organization (with five redundant SRAM die), along with other small scale integrated circuits, decoupling capacitors and pull-up resistors. These devices are placed in a milled out ceramic substrate and electrically interconnected using a patterned overlay process referred to as High Density Interconnect (HDI). This design achieved an unsurpassed die to substrate area efficiency of over 85%. The HDI process was established through a detailed “Rel-Tech” process survey, and the space qualification methodology was derived from previous results used for the Mid-course Sensor Experiment (a Ballistic Missile Defense Organization satellite). Over 300 HCSM modules were built, 280 of which were used to populate two Solid State Recorder (SSR) designs in the TRMM spacecraft. The insertion of HDI into the TRMM program represents: 1) The largest-scale insertion of MCM-D technology in a space flight SSR, and 2) The first MCM-D to be built by three different manufacturers (General Electric, Texas Instruments, and Lockheed Martin/Morristown) to the same specification control drawing