Micro-castellated interposer
A miniature PWB with features that incorporate the required circuitry changes and component footprints, which has been enhanced with micro-castellations such as those found on ceramic surface mount packages. The miniature PWB is mounted on the circuit board using techniques well known in the art. This combination of technologies provides an adaptable, durable interconnect methodology, which allows for circuit and part changes without changing the layout of the base printed wiring board.
1. An apparatus for accommodating circuitry device and interconnect changes externally to a parent printed wiring assembly, the apparatus comprising:
a micro-castellated printed wiring board, said micro-castellated printed wiring board comprising fine features, the printed wiring board comprising a material whose properties account for a coefficient of expansion differences between the changed circuitry devices and a parent printed wiring board from the parent printed wiring assembly;
a first interconnection between said fine features and the changed circuitry devices, said first interconnect comprising:
automated assembly and reflow;
a robust solder joint, wherein the robust solder joint has a specific geometry based on a pad to a part lead geometry and thermal induced stresses;
a unique pad geometry for said changed circuitry devices which defines a footprint; and
a second interconnection between landed castellations of said micro-castellated printed wiring board and the parent printed wiring assembly, the second interconnection including a robust leadless solder joint having a specific geometry based on a pad to castellation geometry ratio and thermal stresses.
2. The apparatus of claim 1 wherein said landed castellations interface directly to parent printed wiring assembly.
3. The apparatus of claim 1 wherein said robust leadless solder joint comprises two distinct soldered zones, a first formed between land patterns comprising a thin structure and a second being formed in the landed castellations which functions as a solder column.
4. The apparatus of claim 1 wherein said landed castellations are formed on an edge of the micro-castellated printed wiring board.
5. The apparatus of claim 1 wherein said landed castellations are formed internal to the micro-castellated printed wiring board comprising partially occluded castellations.
6. The apparatus of claim 1 wherein said landed castellations are formed internal to the micro-castellated printed wiring board comprising fully occluded castellations.
7. The apparatus of claim 1 wherein said second interconnection comprises a means for automated assembly and reflow.