Direct Bond Copper (DBCu)
Direct Bond Copper substrates are thick copper foil clad ceramics using either Alumina (Al2O3) or Aluminum Nitride (AlN) ceramics intended for very high power microelectronic applications such as power supplies, radar systems, thermoelectric coolers, solar cell, high luminosity LEDs and other applications. The copper is bonded in nitrogen furnaces above 1,000°C which limit the copper foil thicknesses from 5‰ to 12‰ thick. This thickness copper limits photopatterning and etching effectively to minimum 10‰ lines and spacing. Copper can be chemically etched down to 3‰ thick copper foil for some tighter patterning requirements in RF and microwave applications. The DBC bond to ceramic is tenacious being one of the strongest bonds of any metal in thick film or thin film metallurgy. Being directly bonded to ceramic without adhesives or thick film interlayer it provides an excellent thermal path to the heat sink. The copper foil can be etched with ferric chloride or copper chloride although the copper is so thick it is more commonly referred to as copper milling.