High-Density Passives - Multi-Layer HDI Substrates

HDI circuitry can be fabricated on a variety of ceramics including 92%, 96%, 99% Al2O3, and AlN. Two sided functionality is achieved by laser machining thru holes and then filling them with a metal paste to create electrical paths that connect circuitry on one side of the substrate to the other. High density circuitry (down to 25um lines/spaces) is accomplished through screen printing specialized thick films onto the substrate and then patterning utilizing photolithography and wet etching processes. Gold and silver based conductors are available. Multi-layer circuitry on either or both sides of the substrate is achieved using patented photosensitive thick film dielectrics capable of producing interconnect vias down to 50um diameter. Traditional printed thick film layers can be incorporated at any process stage where appropriate. Controlled impedance structures along with thick film resistor and inductor elements can also be integrated into the circuit design.



The filled through hole process is also utilized to build what are called VI (vertical interconnect) structures. These are a type of chip to next level interconnect structure that feature excellent high speed performance and in parallel provide a mechanical support structure ideal for chip stacking architectures.