| 摘要 |
An improved surface mount package and method of making such a package is provided. A conventional surface mount package is modified by fabricating a U-shaped via around the lead via to form a quasi-coaxial transmission line through the insulating substrate. This permits the electrical impedance in the conductive elements of the surface mount package to be controlled to reduce insertion loss and return loss, and to improve isolation. The surface mount package includes a lead frame, and a gold plate to which an integrated circuit in the package is attached. The package is sealed with a ring-frame and a lid. Ground vias connecting the lead-frame to the plate through the substrate may also be included. The present package is designed by modelling the various elements of the package as a coaxial transmission line, a co-planar waveguide, and a single lead in a trough transmission line in combination. In an alternative embodiment, the U-shaped via may be formed of discrete holes drilled through the substrate, rather than as a continuous U-shape.
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