A new method of metal-ceramic joining for advanced microelectronic packaging

Materials and processes have been developed for brazing pin, lead, window frame, and heat sink metals to alumina and glass ceramic substrates. The substrates are metallized using copper-, silver-, palladium/silver-, or gold-based thick-film pastes that are fired in the 850 degrees C to 950 degrees C temperature range. The metal-ceramic bond strengths obtained were comparable to those accomplished using high-temperature-fired tungsten- or molybdenum-based metallizations. The brazing capabilities developed enable the low-temperature fired/cofired systems to become a complete packaging scheme. The capabilities developed in the present work, coupled with ceramic circuitization using existing high electrical conductivity metallizations (Cu, Au, or Ag based) and low dielectric constant and low TCE (thermal coefficient of expansion) dielectric thick-film pastes and tapes, offer the package designer extended electrical, thermal, performance, and reliability capabilities not previously available.<
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