HERMETIC HIGH FREQUENCY SURFACE MOUNT MICROELECTRONIC PACKAGE

摘要

A hermetic package for microelectronic circuits comprises a ceramic base with conductive, hermetically sealed vias that connect the metal ground plane on the bottom of the base to the circuit on the top, a ceramic frame sealed to the top of the base, leads sealed between the frame and the base, and a lid sealed to the top of the frame. The vias are cofired with the ceramic base and provide good power dissipation because of their thermal conductivity and good RF grounds to isolate different stages in the circuit. Because the vias are hermetically sealed, no separate bottom component and no brazing operation is required to hermetically seal the package. The leads have a tapered section so the leads are wider outside the package reducing inductance and narrower going through the ceramic frame to reduce capacitance, thus tuning the leads to close to 50 ohm impedence. A layer of conducting silver loaded solder glass underneath the lead electrically connects the lead to the circuit and seals the lead to the base. A nonconducting layer of lead oxide solder glass over the lead seals the lead to the ceramic frame. The top surface of the frame has a metallized layer so that the lid can be hermetically sealed to the frame by soldering.