Patterned conductive epoxy heat-sink attachment in a monolithic microwave integrated circuit (MMIC)

A monolithic microwave integrated circuit structure, comprising:

• a semiconductor substrate structure, comprising:
• a plurality of active devices;
• and
• a microwave transmission line section having:
• an input section;
• an output section;
• and, a interconnecting section electrically interconnecting the active devices on one surface of the substrate;
• a thermally conductive, electrically non-conductive heat sink;
• and
• a thermally conductive bonding layer for bonding the heat sink to an opposite surface of the substrate, the thermally conductive bonding layer comprising:
• an electrically conductive layer portion of a first material extending vertically from the heat sink to the opposite surface of the substrate;
• and,
• an electrically non-conductive layer portion of a second material disposed laterally of the electrically conductive portion and extending vertically from the heat sink to the opposite surface of the substrate;
• wherein the electrically conductive layer portion and the electrically non-conductive layer portion are in a non-overlapping relationship
• wherein the first material is different from the second material;
• wherein the electrically conductive portion is disposed between the heat sink and a first region on said opposite surface of the substrate, the first region directly overlaying the active devices;
• and,
• wherein the electrically non-conductive portion is disposed between the heat sink and a second region on said opposite surface of the substrate, the second region directly overlaying a portion of the microwave transmission line section.