Mounting LPAs On Circuit Boards

APPLICATION NOTE:
Mounting assembled Leaded Power Amplifier (LPA) Packages onto circuit boards.

Special design considerations allow the LPA Packages to operate at high frequency. LPA packages feature leads attached to an alumina ceramic body with one of the strongest ceramic to metal joints available. One element required for operation at high frequency is the use of fine geometry leads. Fine geometry leads are not as robust, and it is possible to exceed the yield or tensile strength even with small hand tools. Even though firmly attached, EXTRA care in handling is essential.

"Do"s

Check all fixtures used for assembly, for lead form, and for test to be sure that parts are not subjected to unnecessary physical stress.

Check that fixtures allow for proper tolerance accumulation.

Check that test sockets are easy to load, and not likely to torque or twist the leads.

For packages that mount with screws, be sure that the package is attached to a flat surface.

"Don't"s

Do not over-torque mounting screws.

Do not use conductive gaskets or shims under the package.

Do not use test fixtures or sockets that may produce a sharp lifting force to lift the lead directly adjacent to the package.

If packages must be removed after solder attach, do not pry the leads up so that the force lifting the lead from the board is also lifting the lead from the package. Use a probe to press down on the lead-to-package joint, and lift the lead when the solder is fluid.

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